Subjects -> ENGINEERING (Total: 2844 journals)
    - CHEMICAL ENGINEERING (259 journals)
    - CIVIL ENGINEERING (255 journals)
    - ELECTRICAL ENGINEERING (182 journals)
    - ENGINEERING (1420 journals)
    - ENGINEERING MECHANICS AND MATERIALS (454 journals)
    - HYDRAULIC ENGINEERING (60 journals)
    - INDUSTRIAL ENGINEERING (101 journals)
    - MECHANICAL ENGINEERING (113 journals)

ENGINEERING (1420 journals)                  1 2 3 4 5 6 7 8 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 9)
3D Research     Hybrid Journal   (Followers: 22)
AAPG Bulletin     Hybrid Journal   (Followers: 11)
Abstract and Applied Analysis     Open Access   (Followers: 4)
Aceh International Journal of Science and Technology     Open Access   (Followers: 9)
ACS Nano     Hybrid Journal   (Followers: 457)
Acta Geotechnica     Hybrid Journal   (Followers: 7)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 10)
Acta Nova     Open Access   (Followers: 1)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 4)
Acta Scientiarum. Technology     Open Access   (Followers: 3)
Acta Universitatis Cibiniensis. Technical Series     Open Access   (Followers: 1)
Active and Passive Electronic Components     Open Access   (Followers: 8)
Adaptive Behavior     Hybrid Journal   (Followers: 9)
Additive Manufacturing Letters     Open Access  
Adsorption     Hybrid Journal   (Followers: 5)
Advanced Energy and Sustainability Research     Open Access   (Followers: 7)
Advanced Engineering Forum     Full-text available via subscription   (Followers: 14)
Advanced Engineering Research     Open Access  
Advanced Journal of Graduate Research     Open Access   (Followers: 4)
Advanced Quantum Technologies     Hybrid Journal   (Followers: 1)
Advanced Science     Open Access   (Followers: 13)
Advanced Science Focus     Free   (Followers: 7)
Advanced Science Letters     Full-text available via subscription   (Followers: 13)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 11)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 20)
Advanced Theory and Simulations     Hybrid Journal   (Followers: 5)
Advances in Applied Energy     Open Access   (Followers: 1)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 7)
Advances in Catalysis     Full-text available via subscription   (Followers: 8)
Advances in Complex Systems     Hybrid Journal   (Followers: 12)
Advances in Engineering Software     Hybrid Journal   (Followers: 31)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 20)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 22)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 30)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 27)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 10)
Advances in Natural Sciences : Nanoscience and Nanotechnology     Open Access   (Followers: 36)
Advances in Operations Research     Open Access   (Followers: 14)
Advances in OptoElectronics     Open Access   (Followers: 6)
Advances in Physics Theories and Applications     Open Access   (Followers: 21)
Advances in Polymer Science     Hybrid Journal   (Followers: 54)
Advances in Porous Media     Full-text available via subscription   (Followers: 6)
Advances in Remote Sensing     Open Access   (Followers: 59)
Advances in Science and Research (ASR)     Open Access   (Followers: 8)
Aerobiologia     Hybrid Journal   (Followers: 4)
Aerospace Systems     Hybrid Journal   (Followers: 10)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 8)
AIChE Journal     Hybrid Journal   (Followers: 38)
Ain Shams Engineering Journal     Open Access   (Followers: 7)
Al-Nahrain Journal for Engineering Sciences     Open Access  
Al-Qadisiya Journal for Engineering Sciences     Open Access   (Followers: 1)
AL-Rafdain Engineering Journal     Open Access   (Followers: 3)
Alexandria Engineering Journal     Open Access   (Followers: 3)
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 27)
American Journal of Engineering and Applied Sciences     Open Access   (Followers: 12)
American Journal of Engineering Education     Open Access   (Followers: 20)
American Journal of Environmental Engineering     Open Access   (Followers: 16)
American Journal of Industrial and Business Management     Open Access   (Followers: 31)
Annals of Civil and Environmental Engineering     Open Access   (Followers: 3)
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Pure and Applied Logic     Open Access   (Followers: 6)
Annals of Regional Science     Hybrid Journal   (Followers: 10)
Annals of Science     Hybrid Journal   (Followers: 10)
Annual Journal of Technical University of Varna     Open Access   (Followers: 1)
Antarctic Science     Hybrid Journal   (Followers: 1)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 3)
Applicable Analysis: An International Journal     Hybrid Journal   (Followers: 2)
Applications in Energy and Combustion Science     Open Access   (Followers: 4)
Applications in Engineering Science     Open Access   (Followers: 1)
Applied Catalysis A: General     Hybrid Journal   (Followers: 8)
Applied Catalysis B: Environmental     Hybrid Journal   (Followers: 22)
Applied Clay Science     Hybrid Journal   (Followers: 6)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 16)
Applied Energy     Partially Free   (Followers: 29)
Applied Engineering Letters     Open Access   (Followers: 5)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 4)
Applied Nanoscience     Open Access   (Followers: 11)
Applied Network Science     Open Access   (Followers: 3)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 6)
Applied Physics Research     Open Access   (Followers: 7)
Applied Rheology     Open Access   (Followers: 1)
Applied Sciences     Open Access   (Followers: 6)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 6)
Arab Journal of Basic and Applied Sciences     Open Access  
Arabian Journal for Science and Engineering     Hybrid Journal   (Followers: 5)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 6)
Archives of Foundry Engineering     Open Access   (Followers: 1)
Archives of Thermodynamics     Open Access   (Followers: 13)
Arctic     Open Access   (Followers: 7)
Arid Zone Journal of Engineering, Technology and Environment     Open Access   (Followers: 2)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ArtefaCToS : Revista de estudios sobre la ciencia y la tecnología     Open Access   (Followers: 1)
Asia-Pacific Journal of Science and Technology     Open Access  
Asian Engineering Review     Open Access  
Asian Journal of Applied Science and Engineering     Open Access   (Followers: 2)
Asian Journal of Applied Sciences     Open Access   (Followers: 2)
Asian Journal of Biotechnology     Open Access   (Followers: 9)
Asian Journal of Control     Hybrid Journal  
Asian Journal of Technology Innovation     Hybrid Journal   (Followers: 7)
Assembly Automation     Hybrid Journal   (Followers: 2)
ATZagenda     Hybrid Journal  
ATZextra worldwide     Hybrid Journal  
AURUM : Mühendislik Sistemleri ve Mimarlık Dergisi = Aurum Journal of Engineering Systems and Architecture     Open Access   (Followers: 1)
Australasian Journal of Engineering Education     Hybrid Journal   (Followers: 3)
Australasian Physical & Engineering Sciences in Medicine     Hybrid Journal   (Followers: 1)
Australian Journal of Multi-Disciplinary Engineering     Hybrid Journal   (Followers: 2)
Autocracy : Jurnal Otomasi, Kendali, dan Aplikasi Industri     Open Access  
Automotive and Engine Technology     Hybrid Journal  
Automotive Experiences     Open Access  
Automotive Innovation     Hybrid Journal   (Followers: 1)
Avances en Ciencias e Ingenierías     Open Access  
Avances: Investigación en Ingeniería     Open Access   (Followers: 6)
Balkan Region Conference on Engineering and Business Education     Open Access   (Followers: 2)
Bangladesh Journal of Scientific and Industrial Research     Open Access  
Basin Research     Hybrid Journal   (Followers: 6)
Batteries     Open Access   (Followers: 11)
Batteries & Supercaps     Hybrid Journal   (Followers: 7)
Bautechnik     Hybrid Journal   (Followers: 3)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 29)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 3)
Beyond : Undergraduate Research Journal     Open Access  
Bhakti Persada : Jurnal Aplikasi IPTEKS     Open Access  
Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Bilge International Journal of Science and Technology Research     Open Access   (Followers: 1)
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 14)
Biomedical Engineering     Hybrid Journal   (Followers: 16)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 14)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 6)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 6)
Biomedical Microdevices     Hybrid Journal   (Followers: 9)
Biomedical Science and Engineering     Open Access   (Followers: 8)
Biomicrofluidics     Open Access   (Followers: 7)
BioNanoMaterials     Open Access   (Followers: 3)
Biotechnology Progress     Hybrid Journal   (Followers: 44)
Black Sea Journal of Engineering and Science     Open Access  
Botswana Journal of Technology     Full-text available via subscription   (Followers: 1)
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access   (Followers: 2)
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 13)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 15)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers Droit, Sciences & Technologies     Open Access   (Followers: 1)
Calphad     Hybrid Journal   (Followers: 2)
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 30)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 50)
Carbon Resources Conversion     Open Access   (Followers: 3)
Carpathian Journal of Electronic and Computer Engineering     Open Access  
Case Studies in Thermal Engineering     Open Access   (Followers: 8)
Catalysis Communications     Hybrid Journal   (Followers: 7)
Catalysis Letters     Hybrid Journal   (Followers: 3)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 9)
Catalysis Science and Technology     Hybrid Journal   (Followers: 13)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 4)
Catalysis Today     Hybrid Journal   (Followers: 8)
CEAS Space Journal     Hybrid Journal   (Followers: 6)
Cell Reports Physical Science     Open Access  
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 2)
Central European Journal of Engineering     Hybrid Journal  
CFD Letters     Open Access   (Followers: 8)
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (Followers: 3)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chaos, Solitons & Fractals : X     Open Access   (Followers: 1)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 3)
Chinese Journal of Engineering     Open Access   (Followers: 2)
Chinese Journal of Population, Resources and Environment     Open Access  
Chinese Science Bulletin     Open Access   (Followers: 1)
Ciencia e Ingenieria Neogranadina     Open Access  
Ciencia en su PC     Open Access   (Followers: 1)
Ciencia y Tecnología     Open Access  
Ciencias Holguin     Open Access   (Followers: 2)
CienciaUAT     Open Access   (Followers: 1)
Cientifica     Open Access  
CIRP Annals - Manufacturing Technology     Hybrid Journal   (Followers: 11)
CIRP Journal of Manufacturing Science and Technology     Hybrid Journal   (Followers: 14)
City, Culture and Society     Hybrid Journal   (Followers: 27)
Clay Minerals     Hybrid Journal   (Followers: 9)
Cleaner Engineering and Technology     Open Access  
Cleaner Environmental Systems     Open Access  
Coastal Engineering     Hybrid Journal   (Followers: 15)
Coastal Engineering Journal     Hybrid Journal   (Followers: 9)
Coastal Engineering Proceedings : Proceedings of the International Conference on Coastal Engineering     Open Access   (Followers: 2)
Coastal Management     Hybrid Journal   (Followers: 30)
Coatings     Open Access   (Followers: 4)
Cogent Engineering     Open Access   (Followers: 3)
Cognitive Computation     Hybrid Journal   (Followers: 3)
Color Research & Application     Hybrid Journal   (Followers: 4)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 19)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 21)
Communications Faculty of Sciences University of Ankara Series A2-A3 Physical Sciences and Engineering     Open Access  
Communications in Numerical Methods in Engineering     Hybrid Journal   (Followers: 2)
Components, Packaging and Manufacturing Technology, IEEE Transactions on     Hybrid Journal   (Followers: 28)
Composite Interfaces     Hybrid Journal   (Followers: 10)
Composite Structures     Hybrid Journal   (Followers: 339)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 281)
Composites Part B : Engineering     Hybrid Journal   (Followers: 313)

        1 2 3 4 5 6 7 8 | Last

Similar Journals
Journal Cover
Coatings
Number of Followers: 4  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2079-6412
Published by MDPI Homepage  [240 journals]
  • Coatings, Vol. 11, Pages 1433: Creation of Bioceramic Coatings on the
           Surface of Ti–6Al–4V Alloy by Plasma Electrolytic Oxidation
           Followed by Gas Detonation Spraying

    • Authors: Bauyrzhan Rakhadilov, Daryn Baizhan
      First page: 1433
      Abstract: In this work, bioceramic coatings were formed on Ti6Al4V titanium alloy using a combined technique of plasma electrolytic oxidation followed by gas detonation spraying of calcium phosphate ceramics, based on hydroxyapatite. Plasma electrolytic oxidation was carried out in electrolytes with various chemical compositions, and the effect of electrolytes on the macro and microstructure, pore size and phase composition of coatings was estimated. Three types of electrolytes based on sodium compounds were used: phosphate, hydroxide, and silicate. Plasma electrolytic oxidation of the Ti–6Al–4V titanium alloy was carried out at a fixed DC voltage (270 V) for 5 min. The sample morphology and phase composition were studied with a scanning electron microscope and an X-ray diffractometer. According to the results, the most homogeneous structure with lower porousness and many crystalline anatase phases was obtained in the coating prepared in the silicate-based electrolyte. A hydroxyapatite layer was obtained on the surface of the oxide layer using detonation spraying. It was determined that the appearance of α-tricalcium phosphate phases is characteristic for detonation spraying of hydroxyapatite, but the hydroxyapatite phase is retained in the coating composition. Raman spectroscopy results indicate that hydroxyapatite is the main phase in the coatings.
      Citation: Coatings
      PubDate: 2021-11-23
      DOI: 10.3390/coatings11121433
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1434: Effect of Al Content on the
           High-Temperature Oxidation Resistance and Structure of CrAl Coatings

    • Authors: Jiaojiao Ma, Chuiyi Meng, Hui Wang, Xiujie He
      First page: 1434
      Abstract: The oxidation behaviors of Cr, Cr93.4Al6.6, Cr58.1Al41.9, and Cr34.5Al65.5 coatings, deposited by using multi-arc ion plating technology, at high temperature were studied. The weight gain, oxide thickness, morphology, and phase composition of the coatings before and after oxidation were analyzed in detail. The results show that there is an Al content window available for tuning the oxidation behaviors of the CrAl-based coatings. The Cr93.4Al6.6 coating is considered to be most protective and can effectively improve the high-temperature oxidation resistance of the substrate; whereas, too high an Al content has a harmful effect on the antioxidant properties of the coatings. The oxidation mechanism of Cr and CrAl coatings were also discussed.
      Citation: Coatings
      PubDate: 2021-11-23
      DOI: 10.3390/coatings11121434
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1435: Annealing Effect on Seebeck Coefficient of
           SiGe Thin Films Deposited on Quartz Substrate

    • Authors: Kaneez Fatima, Hadia Noor, Adnan Ali, Eduard Monakhov, Muhammad Asghar
      First page: 1435
      Abstract: Over the past few years, thermoelectrics have gained interest with regard to thermoelectricity interconversion. The improvement in the efficiency of the thermoelectric material at an ambient temperature is the main problem of research. In this work, silicon–germanium (SiGe) thin films, owing to superior properties such as nontoxicity, high stability, and their integrability with silicon technologies, were studied for thermoelectric applications. P-type SiGe thin films were deposited on quartz substrates by DC/RF magnetron sputtering and annealed at three different temperatures for 1 hour. Significant enhancement in the Seebeck coefficient was achieved for the sample annealed at 670 °C. A high power factor of 4.1 μWcm−1K−2 was obtained at room temperature.
      Citation: Coatings
      PubDate: 2021-11-23
      DOI: 10.3390/coatings11121435
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1436: Study on the Optimum Steel Slag Content of
           SMA-13 Asphalt Mixes Based on Road Performance

    • Authors: Wei Chen, Jincheng Wei, Xizhong Xu, Xiaomeng Zhang, Wenyang Han, Xiangpeng Yan, Guiling Hu, Zizhao Lu
      First page: 1436
      Abstract: To reduce the use of aggregates such as limestone and basalt, this paper used steel slag to replace some of the limestone aggregates in the production of SMA-13 asphalt mixes. The optimum content of steel slag in the SMA-13 asphalt mixes was investigated, and the performance of these mixes was evaluated. Five SMA-13 asphalt mixes with varying steel slag content (0%, 25%, 50%, 75%, and 100%) were designed and prepared experimentally. The high-temperature stability, low-temperature crack resistance, water stability, dynamic modulus, shear resistance, and volumetric stability of the mixes were investigated using the wheel tracking, Hamburg wheel tracking, three-point bending, freeze–thaw splitting, dynamic modulus, uniaxial penetration, and asphalt mix expansion tests. The results showed that compared to normal SMA-13 asphalt mixes, the high-temperature stability, water stability, and shear resistance of the SMA-13 asphalt mixes increased and then decreased as the steel slag content increased. All three performance indicators peaked at 75% steel slag content, and the dynamic stability, freeze–thaw splitting ratio, and uniaxial penetration strength increased by 90.48%, 7.39%, and 88.08%, respectively; however, the maximum bending tensile strain, which represents the low-temperature crack resistance of the asphalt mix, decreased by 5.98%. The dynamic modulus of the SMA-13 asphalt mixes increased with increasing steel slag content, but the volume expansion at a 75% steel slag content was 0.446% higher than at a 0% steel slag content. Based on the experimental results, the optimum content of steel slag for SMA-13 asphalt mixes was determined to be 75%.
      Citation: Coatings
      PubDate: 2021-11-23
      DOI: 10.3390/coatings11121436
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1437: Ferroelectric and Ferroelastic Domain
           Related Formation and Influential Mechanisms of Vapor Deposited
           Piezoelectric Thin Films

    • Authors: Chu Chen, Jian Song, Qi Zhang, Mingyu Gong, Yue Liu, Tongxiang Fan
      First page: 1437
      Abstract: Compared to the bulk piezoelectric materials counterpart, piezoelectric thin films (PTFs) possess advantages of smaller size, lower power consumption, better sensitivity, and have broad application in advanced micro-electro-mechanical system (MEMS) devices. However, the performance of MEMS transducers and actuators are largely limited by PTFs piezoelectric properties. In this review, we focus on understanding structure-property relationship of vapor deposited PTFs, with emphasis on the effect of strain energy and electrostatic energy in thin films, especially, energy relaxation induced misfit dislocation and ferroelectric (FS) and ferroelastic (FC) domain formation mechanisms. We then discuss the microstructure of these domains and their influential mechanisms on piezoelectric properties, as well as the domain engineering strategies (i.e., internal and external stimuli). This review will motivate further experimental, theoretical, and simulation studies on FS and FC domain engineering in PTFs.
      Citation: Coatings
      PubDate: 2021-11-24
      DOI: 10.3390/coatings11121437
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1438: Mixtures of Scutellaria baicalensis and
           Glycyrrhiza L. Extracts as Antibacterial and Antiviral Agents in Active
           Coatings

    • Authors: Magdalena Ordon, Paweł Nawrotek, Xymena Stachurska, Anna Schmidt, Małgorzata Mizielińska
      First page: 1438
      Abstract: The aim of this study was to develop active packaging materials covered in active coatings (offering antibacterial and antiviral properties) that contain selected plant extracts. In addition, the synergistic effect of the active substances in these extracts was also analysed. The results of the study demonstrated that Scutellaria baicalensis and Glycyrrhiza L. extracts (two of six analysed plant extracts) were the most active agents against selected Gram-positive and Gram-negative bacterial strains. Additionally, the synergistic effect of S. baicalensis and Glycyrrhiza L. extracts was noted, meaning that the effect of these two plant extract mixtures on Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas syringae growth was higher than the activity of individual pure extracts. Mixtures of the extracts were introduced into the coating carrier. A polyethylene (PE) foil was then coated with active layers containing mixtures of S. baicalensis and Glycyrrhiza L. extracts as antimicrobial agents. The results of this research showed that all of the active coatings had a bacteriolytic effect on B. subtilis and a bacteriostatic effect on S. aureus cells. The coatings were found to be inactive against E. coli and P. syringae cells. This means that the coatings could be used as internal coatings to preserve food products against Gram-positive bacteria that may be responsible for food spoilage. The results of this study also demonstrated that the coatings were highly active against phage phi 6 phage particles, used as SARS-CoV-2 surrogate. This means that the coatings could be used as external coatings to limit the spread of SARS-CoV-2 and pathogenic Gram-positive bacteria via human hands.
      Citation: Coatings
      PubDate: 2021-11-24
      DOI: 10.3390/coatings11121438
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1439: Influence of Applied Frequency on Thermal
           Physical Properties of Coatings Prepared on Al and AlSi Alloys by Plasma
           Electrolytic Oxidation

    • Authors: Guodong Li, Fei Ma, Zhijie Li, Yi Xu, Fangyuan Gao, Lingyan Guo, Jianwei Zhu, Guang Li, Yuan Xia
      First page: 1439
      Abstract: In this study, plasma electrolytic oxidation (PEO) was performed on Al and AlSi substrates using a pulsed direct current (DC) power source. The coating process was carried out in a Na2SiO3 electrolyte with the systematic change of pulse frequency (50–1400 Hz). The surface characteristics of the coatings were examined using scanning electron microscopy (SEM). The phase structure was characterized using X-ray diffraction (XRD). A differential scanning calorimeter (DSC) and a laser flash apparatus (LFA) were employed to test heat capacity and heat conductivity, respectively. Results showed that as the discharge frequency increased, the thermal physical properties of Al-PEO and AlSi-PEO coatings changed in different ways. At a high frequency, Al-PEO coatings had low porosity and were closed-pore structured whereas AlSi-PEO coatings had high porosity and large-size open-pore structures could be observed on their surfaces due to concentrated discharges. Based on these findings, it was found that the thermal productivity of coatings is closely correlated with the open-/closed-pore structure instead of porosity. PEO coatings with low heat capacity or low heat conductivity could be obtained with a controlled frequency.
      Citation: Coatings
      PubDate: 2021-11-24
      DOI: 10.3390/coatings11121439
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1440: Methods to Generate Structurally
           Hierarchical Architectures in Nanoporous Coinage Metals

    • Authors: Palak Sondhi, Keith J. Stine
      First page: 1440
      Abstract: The fundamental essence of material design towards creating functional materials lies in bringing together the competing aspects of a large specific surface area and rapid transport pathways. The generation of structural hierarchy on distinct and well-defined length scales has successfully solved many problems in porous materials. Important applications of these hierarchical materials in the fields of catalysis and electrochemistry are briefly discussed. This review summarizes the recent advances in the strategies to create a hierarchical bicontinuous morphology in porous metals, focusing mainly on the hierarchical architectures in nanoporous gold. Starting from the traditional dealloying method and subsequently moving to other non-traditional top-down and bottom-up manufacturing processes including templating, 3D printing, and electrodeposition, this review will thoroughly examine the chemistry of creating hierarchical nanoporous gold and other coinage metals. Finally, we conclude with a discussion about the future opportunities for the advancement in the methodologies to create bimodal structures with enhanced sensitivity.
      Citation: Coatings
      PubDate: 2021-11-24
      DOI: 10.3390/coatings11121440
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1441: Study of Wear and Redistribution Dynamic
           Forces of Wheel Pairs Restored by a Wear-Resistant Coating 15Cr17Ni12V3F

    • Authors: Vitaliy V. Savinkin, Zaure Zh. Zhumekenova, Andrei Victor Sandu, Petrica Vizureanu, Sergey V. Savinkin, Sergey N. Kolisnichenko, Olga V. Ivanova
      First page: 1441
      Abstract: The relevance of this study lies in the need to research the wear process of the elements of dynamic systems and to establish the dependence of the geometric and structural characteristics of wheels restored by plasma surfacing with a coating of 15Cr17Ni12V3F on dynamic, cyclically varying loads. The study was aimed to establish the dependencies between the deviation of the wear area, the formation of contact and fatigue stresses, and the change in the phase structure of the wheel defect. It is important to justify the permissible limits of wear of the transverse profile in the contact zone of a wheel and ridge. The object of the study was the dynamic interaction of the “wheel–ridge–rail contact surface” system. To achieve the goal, the following methodology was adopted: kinematic analysis, strength calculation, the use of mathematical analysis in dynamic system modelling, virtual modelling in the SOLIDWORKS software environment of the GearTrax application, experiment planning, and model correction through the results of metallographic studies. The results of the study are presented as reasonable prediction criteria that consider contact cycles during the formation of fatigue stresses at the stage of defect origin. The process of the dynamic interaction of the contact worn profile of a wheel with a railway rail is explored. Polynomial equations are proposed to substantiate the optimal design and technological parameters of designing a railway carriage wheel. The permissible limits of wear of the transverse profile in the contact zone of the wheel and the ridge are justified while taking the coefficient of the reduction of contact stresses in the metal into account. The dependences of the change in static load on the utilization factor of the railway carriage load capacity are established. The dependences of changes in fatigue stresses on the design deviation of the contact area of wheel wear are established. It is confirmed that the stress concentration under cyclic loads is formed in the ferritic layers of the material structure before the appearance of wear.
      Citation: Coatings
      PubDate: 2021-11-24
      DOI: 10.3390/coatings11121441
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1442: Enhancement of Charge Transport of a
           Dye-Sensitized Solar Cell Utilizing TiO2 Quantum Dot Photoelectrode Film

    • Authors: Siti Nur Azella Zaine, Norani Muti Mohamed, Mehboob Khatani, Muhammad Umair Shahid
      First page: 1442
      Abstract: A dye-sensitized solar cell (DSC) is the third generation of solar technology, utilizing TiO2 nanoparticles with sizes of 20–30 nm as the photoelectrode material. The integration of smaller nanoparticles has the advantage of providing a larger surface area, yet the presence of grain boundaries is inevitable, resulting in a higher probability of electron trapping. This study reports on the improvement of charge transport through the integration of quantum dot (QD) TiO2 with a size of less than 10 nm as the dye absorption photoelectrode layer. The QD TiO2 samples were synthesized through sol–gel and reflux methods in a controlled pH solution without surfactants. The synthesized samples were analyzed using microscopic, diffraction, absorption, as well as spectroscopic analyses. A current–voltage and impedance analysis was used to evaluate the performance of a DSC integrated with synthesized TiO2 as the photoelectrode material. The sample with smaller crystallite structures led to a large surface area and exhibited a higher dye absorption capability. Interestingly, a DSC integrated with QD TiO2 showed a higher steady-state electron density and a lower electron recombination rate. The shallow distribution of the trap state led to an improvement of the electron trapping/de-trapping process between the Fermi level and the conduction band of oxide photoelectrode material, hence improving the lifetime of generated electrons and the overall performance of the DSC.
      Citation: Coatings
      PubDate: 2021-11-24
      DOI: 10.3390/coatings11121442
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1443: Deuterium Retention and Release Behavior
           from Beryllium Co-Deposited Layers at Distinct Ar/D Ratio

    • Authors: Paul Dinca, Cornel Staicu, Corneliu Porosnicu, Oana G. Pompilian, Ana-Maria Banici, Bogdan Butoi, Cristian P. Lungu, Ion Burducea
      First page: 1443
      Abstract: Beryllium-deuterium co-deposited layers were obtained using DC magnetron sputtering technique by varying the Ar/D2 gas mixture composition (10/1; 5/1; 2/1 and 1:1) at a constant deposition rate of 0.06 nm/s, 343 K substrate temperature and 2 Pa gas pressure. The surface morphology of the layers was analyzed using Scanning Electron Microscopy and the layer crystalline structure was analyzed by X-ray diffraction. Rutherford backscattering spectrometry was employed to determine the chemical composition of the layers. D trapping states and inventory quantification were performed using thermal desorption spectroscopy. The morphology of the layers is not influenced by the Ar/D2 gas mixture composition but by the substrate type and roughness. The increase of the D2 content during the deposition leads to the deposition of Be-D amorphous layers and also reduces the layer thickness by decreasing the sputtering yield due to the poisoning of the Be target. The D retention in the layers is dominated by the D trapping in low activation binding states and the increase of D2 flow during deposition leads to a significant build-up of deuterium in these states. Increase of deuterium flow during deposition consequently leads to an increase of D retention in the beryllium layers up to 300%. The resulted Be-D layers release the majority of their D (above 99.99%) at temperatures lower than 700 K.
      Citation: Coatings
      PubDate: 2021-11-24
      DOI: 10.3390/coatings11121443
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1444: Microstructure and Mechanical Properties of
           Carbide Reinforced TiC-Based Ultra-High Temperature Ceramics: A Review

    • Authors: Haobo Mao, Fuqiang Shen, Yingyi Zhang, Jie Wang, Kunkun Cui, Hong Wang, Tao Lv, Tao Fu, Tianbiao Tan
      First page: 1444
      Abstract: TiC ceramics have become one of the most potential ultra-high temperature structural materials, because of its high melting point, low density, and low price. However, the poor mechanical properties seriously limit its development and application. In this work, this review follows PRISMA standards, the mechanism of the second phase (particles, whiskers, and carbon nanotubes) reinforced TiC ceramics was reviewed. In addition, the effects of the second phase on the microstructure, phase composition and mechanical properties of TiC ceramics were systematically studied. The addition of carbon black effectively eliminates the residual TiO2 in the matrix, and the bending strength of the matrix is effectively improved by the strengthening bond formed between TiC; SiC particles effectively inhibit the grain growth through pinning, the obvious crack deflection phenomenon is found in the micrograph; The smaller grain size of WC plays a dispersion strengthening role in the matrix and makes the matrix uniformly refined, and the addition of WC forms (Ti, W) C solid solution, WC has a solid solution strengthening effect on the matrix; SiC whiskers effectively improve the fracture toughness of the matrix through bridging and pulling out, the microscopic diagram and mechanism diagram of SiC whisker action process are shown in this paper. The effect of new material carbon nanotubes on the matrix is also discussed; the bridging effect of CNTs can effectively improve the strength of the matrix, during sintering, some CNTs were partially expanded into GNR, in the process of crack bridging and propagation, more fracture energy is consumed by flake GNR. Finally, the existing problems of TiC-based composites are pointed out, and the future development direction is prospected.
      Citation: Coatings
      PubDate: 2021-11-24
      DOI: 10.3390/coatings11121444
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1445: Effect of Harvesting Stages and Calcium
           Chloride Application on Postharvest Quality of Tomato Fruits

    • Authors: Mohammad Nurun Nabi Mazumder, Azizah Misran, Phebe Ding, Puteri Edaroyati Megat Wahab, Azhar Mohamad
      First page: 1445
      Abstract: Tomatoes are a good source of vitamins, minerals, antioxidants, and enzymes, which are beneficial to human health. They are one of the most commercially high-value vegetable crops that experience a huge postharvest loss after harvest. The present experiment is conducted to investigate the effect of different maturity stages (mature green, breaker, and half-ripe stage), pre- and post-harvest treatment with different concentrations (0.0%, 1.0%, 1.5%, and 2.0%, w/v) of calcium chloride (CaCl2) on the postharvest performance, antioxidant and enzymatic activity of lowland tomato fruits, stored at ambient temperature (28 ± 2  °C and 75 ± 5% RH). Tomato fruit of mature green stage treated with 2% CaCl2 significantly (p = 0.05) declined the ethylene production (15.53%), weight loss (16.43%), and delayed color development by slowly synthesizes the lycopene content as well as extended the shelf life. The maximum amount of total phenolic content (TPC) was demonstrated at the highest level of CaCl2 (2%) after 20 days of storage life at ambient conditions. The concentration of CaCl2 influenced the activity of different plant defense enzymes, and the higher doses of CaCl2 (2%) accelerated the activity of peroxidase (POD) (13%), polyphenol oxidase (POP) (7.3%), and phenylalanine ammonia-lyase (PAL) (8.5%) relative to that of the control samples. Therefore, the tomato producers and traders could extend the storage duration of tomato fruits by harvesting at the mature green stage and applying 2% CaCl2 in both pre-and postharvest at ambient storage conditions.
      Citation: Coatings
      PubDate: 2021-11-24
      DOI: 10.3390/coatings11121445
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1446: β-Ti Alloys for Orthopedic and Dental
           Applications: A Review of Progress on Improvement of Properties through
           Surface Modification

    • Authors: Longfei Shao, Yiheng Du, Kun Dai, Hong Wu, Qingge Wang, Jia Liu, Yujin Tang, Liqiang Wang
      First page: 1446
      Abstract: Ti and Ti alloys have charming comprehensive properties (high specific strength, strong corrosion resistance, and excellent biocompatibility) that make them the ideal choice in orthopedic and dental applications, especially in the particular fabrication of orthopedic and dental implants. However, these alloys present some shortcomings, specifically elastic modulus, wear, corrosion, and biological performance. Beta-titanium (β-Ti) alloys have been studied as low elastic modulus and low toxic or non-toxic elements. The present work summarizes the improvements of the properties systematically (elastic modulus, hardness, wear resistance, corrosion resistance, antibacterial property, and bone regeneration) for β-Ti alloys via surface modification to address these shortcomings. Additionally, the shortcomings and prospects of the present research are put forward. β-Ti alloys have potential regarding implants in biomedical fields.
      Citation: Coatings
      PubDate: 2021-11-25
      DOI: 10.3390/coatings11121446
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1447: Experimental and Numerical Investigation of
           Light-Wood-Framed Shear Walls Strengthened with Parallel Strand Bamboo
           Panels

    • Authors: Jing Di, Hongliang Zuo
      First page: 1447
      Abstract: This paper describes experimental and numerical investigations on a new type of strengthened light-wood-framed (LWF) shear wall (SW) that has parallel strand bamboo (PSB) panels at each end. The experiments are divided into two parts: (1) monotonic loading tests of panel-to-frame joints representing different positions along the wall; (2) monotonic loading tests of a group of traditional full-scale SWs and two groups of strengthened walls with nailed or screwed PSB panels. The failure modes, load–displacement curves, ultimate bearing capacity, elastic stiffness, and dissipation are analyzed, and the mechanical properties of panel-to-frame joints and the lateral performance of SWs are discussed. Moreover, nonlinear finite-element analysis shows that the numerical results are in good agreement with the test results. Our findings suggest that using LWF SWs strengthened with nailed PSB panels effectively improves the failure mode and the ductility, stiffness, and dissipation of traditional walls. Using sheathing screws on the PSB panels increases the lateral bearing capacity and the dissipation of the walls, but decreases their ductility ratio. Setting end PSB panels improves the overturning resistance capacity by restricting the uplift of studs. The LWF SWs strengthened with end PSB panels are found to meet the design requirements and reduce construction costs.
      Citation: Coatings
      PubDate: 2021-11-25
      DOI: 10.3390/coatings11121447
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1448: Synergetic Design of Transparent Topcoats
           on ITO-Coated Plastic Substrate to Boost Surface Erosion Performance

    • Authors: Xuan Zhang, Yuandong Chen, Wenqiao Zhang, Yanli Zhong, Pei Lei, Changshan Hao, Yue Yan
      First page: 1448
      Abstract: Transparent conductive films (TCFs) have received much research attention in the area of aeronautical canopies. However, bad wear, corrosion resistance and weak erosion performance of TCFs dramatically limit their scalable application in the next-generation aeronautical and optoelectronic devices. To address these drawbacks, three types of optically transparent coatings, including acrylic, silicone and polyurethane (PU) coatings were developed and comparatively investigated ex situ in terms of Taber abrasion, nanoindentation and sand erosion tests to improve the wear-resistance and sand erosion abilities of ITO-coated PMMA substrates. To elucidate the sand erosion failure of the coatings, the nanoindentation technique was employed for quantitative assessment of the shape recovery abilities under probe indentation. Results show that the PU topcoats can greatly enhance the sand erosion properties, which were superior to those of acrylic and silicone topcoats. This result can be attributed to the good toughness and self-healing properties of PU topcoats. Additionally, high hardness and good Taber abrasion properties of the ITO films and silicone topcoats did not have an obvious or affirmatory effect on the sand erosion abilities, based on their brittleness and irreparable properties under sand erosion.
      Citation: Coatings
      PubDate: 2021-11-25
      DOI: 10.3390/coatings11121448
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1449: Influence of Hydrogen-Nitrogen Hybrid
           Passivation on the Gate Oxide Film of n-Type 4H-SiC MOS Capacitors

    • Authors: Yifan Jia, Shengjun Sun, Xiangtai Liu, Qin Lu, Ke Qin, Shaoqing Wang, Yunhe Guan, Haifeng Chen, Xiaoyan Tang, Yuming Zhang
      First page: 1449
      Abstract: Hydrogen-nitrogen hybrid passivation treatment for growing high-property gate oxide films by high-temperature wet oxidation, with short-time NO POA, is proposed and demonstrated. Secondary ion mass spectroscopy (SIMS) measurements show that the proposed method causes hydrogen and appropriate nitrogen atoms to accumulate in Gaussian-like distributions near the SiO2/SiC interface. Moreover, the hydrogen atoms are also incorporated into the grown SiO2 layer, with a concentration of approximately 1 × 1019 cm−3. The conductance characteristics indicate that the induced hydrogen and nitrogen passivation atoms near the interface can effectively reduce the density of interface traps and near-interface traps. The current-voltage (I-V), X-ray photoelectron spectroscopy (XPS), and time-dependent bias stress (TDBS) with ultraviolet light (UVL) irradiation results demonstrate that the grown SiO2 film with the incorporated hydrogen passivation atoms can effectively reduce the density of oxide electron traps, leading to the barrier height being improved and the leakage current being reduced.
      Citation: Coatings
      PubDate: 2021-11-26
      DOI: 10.3390/coatings11121449
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1450: Study the Passivation Characteristics of
           Microwave Annealing Applied to APALD Deposited Al2O3 Thin Film

    • Authors: Yu-Chun Huang, Ricky Wenkuei Chuang, Keh-Moh Lin, Tsung-Chieh Wu
      First page: 1450
      Abstract: In this study, a self-developed atmospheric pressure atomic layer deposition (APALD) system is used to deposit Al2O3 passivation film, along with the use of precursor combinations of Al(CH3)3/H2O to improve its passivation characteristics through a short-time microwave post-annealing process. Comparing the unannealed and microwave-annealed samples whose temperature is controlled at 200–500 °C, APALD non-vacuum deposited film can be realized with a higher film deposition rate, which is beneficial for increasing the production throughput while at the same time reducing the operating cost of vacuum equipment at hand. Since the microwave has a greater penetration depth during the process, the resultant thermal energy provided can be spread out evenly to the entire wafer, thereby achieving the effect of rapid annealing. The film thickness is subsequently analyzed by TEM, whereas the chemical composition is verified by EDS and XPS. The negative fixed charge and interface trap density are analyzed by the C-V measurement method. Finally, the three major indicators of τeff, SRV, and IVoc are analyzed by QSSPC to duly verify the excellent passivation performance.
      Citation: Coatings
      PubDate: 2021-11-25
      DOI: 10.3390/coatings11121450
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1451: Polyacrylate Decorating Poly(ethylene
           terephthalate) (PET) Film Surface for Boosting Oxygen Barrier Property

    • Authors: Wen Zhong, Xiaobin Yang, Jikun Sun, Hongwei Gao, Yongping Bai, Lu Shao
      First page: 1451
      Abstract: Polymeric barrier materials are critical in contemporary industries for food, medicine, and chemical packaging. However, these materials, such as PET films, are impeded by the optimization of barrier properties by virtue of molecular design. Herein, a new methyl methacrylate-methyl acrylate-diallyl maleate-maleic acid (MMA-MAc-DAM-MA) was synthesized to tailor the surface properties of PET films for maximizing oxygen barrier properties. During the MMA-MAc-DAM-MA coating and curing process, the chemical structure evolutions of MMA-MAc-DAM-MA coatings were characterized, indicating that the cross-linking conversion and proportion of –COOH groups are critical for the oxygen barrier properties of coatings. The inherent –COOH groups are transformed into designed structures, including intramolecular anhydride, inter-chain anhydride and retained carboxylic acid. Therein, the inter-chain anhydride restraining the activity of coated polymer chain mainly contributes to enhanced barrier properties. The thermal properties of novel coatings were analyzed, revealing that the curing behavior is strongly dependent on the curing temperatures. The impacts of viscosity of the coating solution, coating velocity, and coating thickness on the oxygen permeability (Po2) of the coatings were investigated using a gas permeability tester to explore the optimum operating parameters during practical applications, which can reduce the Po2 of PET film by 47.8%. This work provides new insights on advanced coating materials for excellent barrier performance.
      Citation: Coatings
      PubDate: 2021-11-26
      DOI: 10.3390/coatings11121451
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1452: Synthesis, Characterization and
           Photodegradation Studies of Copper Oxide–Graphene Nanocomposites

    • Authors: Indah Raya, Awais Ahmad, Ayad F. Alkaim, Dmitry Bokov, Enas R. Alwaily, Rafael Luque, Mabkhoot Alsaiari, Mohammed Jalalah
      First page: 1452
      Abstract: In this work, a simple hydrothermal method was employed to prepare a pristine sample of copper oxide (CuO) and three samples of copper oxide–graphene nanocomposites (CuO-xG) with x = 2.5, 5, and 10 mg of graphene. The synthesized samples were characterized using X-ray powder diffractometry (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FTIR) and ultraviolet–visible (UV-Vis) spectroscopy. The XRD patterns of CuO-xG nanocomposites exhibited the diffraction peaks related to the crystal planes of monoclinic CuO and hexagonal graphite. The surface morphology of the prepared samples was investigated using FESEM images. EDX analysis was used to investigate the chemical composition of the synthesized samples. FTIR spectroscopy identified the vibrational modes of the covalent bonds present in the samples. The allowed direct optical bandgap energy was calculated for all prepared samples using UV-Vis absorption spectra. The small bandgap of CuO-xG nanocomposites indicates their potential use as an effective photocatalyst in the presence of visible light. Photocatalytic activity of the samples was explored for the degradation of methylene blue (MB) dye contaminant under visible light irradiation. The results showed that the CuO-5G sample has the highest photodegradation efficiency (~56%).
      Citation: Coatings
      PubDate: 2021-11-26
      DOI: 10.3390/coatings11121452
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1453: Synergic Effect of Microorganism and
           Colloidal Biochar-Based Organic Fertilizer on the Growth and Fruit Quality
           of Tomato

    • Authors: Shiguo Gu, Fei Lian, Hanyue Yang, Yaru Han, Wei Zhang, Fan Yang, Jie Gao
      First page: 1453
      Abstract: It is well known that carbon-based organic fertilizer can effectively promote crop growth and improve nutrient utilization efficiency. However, little is known about the effect of microorganisms on the nutrient availability of carbon-based organic fertilizer. To elucidate the contribution of microorganisms to the agricultural benefit of colloidal biochar-based fertilizer, a 5-month pot experiment was conducted to study the effect of different combinations of Methyltrophic bacillus, colloidal biochar, and organic fertilizer on physical–chemical properties of soil, plant growth, physiological-biochemical reactions, yield, and quality of tomato. The results show that the addition of Methyltrophic bacillus effectively promoted the availability of soil nutrients (such as nitrate nitrogen and available potassium) and increased soil cation exchange capacity; meanwhile, it significantly increased the content of chlorophyll-a (9.42–27.41%) and promoted the net photosynthetic rate (10.86–13.73%) and biomass of tomato fruit (17.84–26.33%). The contents of lycopene, vitamin C, total sugar, and soluble sugar in the fruits treated by the ternary combination of Methyltrophic bacillus, colloidal biochar, and organic fertilizer increased by 58.40%, 46.53%, 29.45%, and 26.65%, respectively. The above results demonstrate that the addition of beneficial microorganisms could further improve the performance of biochar-based fertilizer on plant growth, yield, and fruit quality of tomato. This information provides evidence for the promising performance of microorganism-supported biochar organic fertilizer in agricultural applications.
      Citation: Coatings
      PubDate: 2021-11-26
      DOI: 10.3390/coatings11121453
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1454: Mechanism of Polyurethane Binder Curing
           Reaction and Evaluation of Polyurethane Mixture Properties

    • Authors: Min Sun, Yufeng Bi, Wei Zhuang, Sai Chen, Pinhui Zhao, Dezheng Pang, Wensheng Zhang
      First page: 1454
      Abstract: This study focuses on analyzing the curing reaction mechanism of polyurethane (PU) binders and comprehensively evaluating the PU mixture’s properties. The former was investigated by conducting a Fourier transform infrared spectroscopy (FTIR) test on PU binders with different curing times. The volume change characteristics, construction operation time, and strength formation law were clarified through the splitting tensile test of PU mixtures under different environmental conditions. The optimal PU mixture stacking time and curing time under different environmental conditions were determined. The properties of the PU mixture and asphalt mixture were evaluated and compared through a rutting test, low-temperature bending test, freeze–thaw splitting test, and four-point bending fatigue test. The results show that the physical and chemical curing of the PU binder occurred within the first 24 h of curing, and the reaction speed gradually accelerated to form a polyurea structure 24 h later. It is recommended to stack the PU mixture for 4 h before compaction and to cure it for 2 days before opening under the conditions of 50% humidity and 15–40 °C surrounding temperature. The PU mixture shows better temperature stability and fatigue resistance than the asphalt mixture, and the splitting tensile strength of the PU mixture before and after the freeze–thaw splitting test is also higher. It is clear that the PU mixture is a green road building material with good performance.
      Citation: Coatings
      PubDate: 2021-11-26
      DOI: 10.3390/coatings11121454
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1455: Providing a Specified Level of
           Electromagnetic Shielding with Nickel Thin Films Formed by DC Magnetron
           Sputtering

    • Authors: Oleg A. Testov, Andrey E. Komlev, Kamil G. Gareev, Ivan K. Khmelnitskiy, Victor V. Luchinin, Eugeniy N. Sevost’yanov, Igor O. Testov
      First page: 1455
      Abstract: Nickel films of 4–250 nm thickness were produced by DC magnetron sputtering onto glass and silicon substrates. The electrical properties of the films were investigated by the four-probe method and the surface morphology of the films was studied by atomic force microscopy. To measure the shielding effectiveness, a portable closed stand based on horn antennas was used. A theoretical assessment of the shielding effectiveness of nickel films of various thickness under electromagnetic radiation of a range of frequencies was carried out using two different approximations. The results demonstrate the shielding effectiveness of up to 35 dB of the nickel thin films in the frequency range of 2–18 GHz.
      Citation: Coatings
      PubDate: 2021-11-26
      DOI: 10.3390/coatings11121455
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1456: Effect of High−Speed Powder Feeding
           on Microstructure and Tribological Properties of Fe−Based Coatings
           by Laser Cladding

    • Authors: Qiang Wang, Runling Qian, Ju Yang, Wenjuan Niu, Liucheng Zhou, Xinlei Pan, Chengming Su
      First page: 1456
      Abstract: In order to improve the wear resistance of 27SiMn steel substrate, Fe−based alloy coatings were prepared by laser cladding technology in the present study. In comparison to the conventional gravity powder feeding (GF) process, high−speed powder feeding (HF) process was used to prepare Fe−based alloy coating on 27SiMn steel substrate. The effect of diversified energy composition of powder materials on the microstructure and properties of coatings were systematically studied. X−ray diffractometer (XRD), optical microscope (OM) and scanning electron microscope (SEM) were used to analyze the phase structure and microstructure of Fe−based alloy coatings, and the hardness and tribological properties were measured by the microhardness tester and ball on disc wear tester, respectively. The results show that the microstructure of conventional gravity feeding (GF) coatings was composed of coarse columnar crystals. In comparison, owing to the diversification of energy composition, the microstructure of the high−speed powder feeding (HF) coatings consists of uniform and small grains. The total energy of the HF process was 75.5% of that of the GF process, proving that high−efficiency cladding can be achieved at lower laser energy. The refinement of the microstructure is beneficial to improve the hardness and wear resistance of the coating, and the hardness of the HF coating increased by 9.4% and the wear loss decreased to 80.5%, compared with the GF coating. The wear surface of the HF coating suffered less damage, and the wear mechanism was slightly adhesive wear. In contrast, wear was more serious in the GF coating, and the wear mechanism was transformed into severe adhesive wear.
      Citation: Coatings
      PubDate: 2021-11-26
      DOI: 10.3390/coatings11121456
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1457: Study on Wear Resistance and Corrosion
           Resistance of HVOF Surface Coating Refabricate for Hydraulic Support
           Column

    • Authors: Mian Wu, Lin Pan, Haitao Duan, Changxin Wan, Tian Yang, Mingchuan Gao, Siliang Yu
      First page: 1457
      Abstract: The hydraulic support column bears loading and makes reciprocating motion ceaselessly for extended periods, so its service life is far shorter than that of the overall hydraulic support. This paper offers a comparative study on the surface coating of hydraulic support columns with hard chrome plating and high-velocity oxygen fuel (HVOF) thermal spraying refabricating to analyze the impact of different refabricating processes on the microstructure, hardness, corrosion resistance, and wear resistance of the coating (plating). The result shows that the structure of the HVOF coating is uniformly compact, and the HVOF WC10Co4Cr coating has better wear resistance, more than four times that of hard chrome plating. In the neutral salt spray test, the HVOF Ni60 coating shows rustiness at 720 h of the test, which suggests its corrosion resistance is nearly five times that of hard chrome plating. Hence, under the harsh corrosive wear environment, the refabricating HVOF Ni60 is a more suitable replacement for the hydraulic support column coating than the hard chrome plating. Thus, the HVOF Ni60 coating could be an effective replacement for hard chrome plating.
      Citation: Coatings
      PubDate: 2021-11-27
      DOI: 10.3390/coatings11121457
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1458: Ship Painting Process Design Based on
           IDBSACN-RF

    • Authors: Henan Bu, Xin Yuan, Jianmin Niu, Wenjuan Yu, Xingyu Ji, Hongyu Lyu, Honggen Zhou
      First page: 1458
      Abstract: The painting process is an essential part of the shipbuilding process. Its quality is directly related to the service life and maintenance cost of the ship. Currently, the design of the painting process relies on the experience of technologists. It is not conducive to scientific management of the painting process and effective control of painting cost. Therefore, an intelligent design algorithm for the ship painting process is proposed in this paper. Density-Based Spatial Clustering of Applications with Noise (DBSCAN) is used to form categories of painting objects by cluster analysis. The grey wolf optimization (GWO) is introduced to realize the adaptive determination of clustering parameters and avoid the deviation of clustering results. Then, a painting object classification model is constructed based on the random forest (RF). Finally, the recommendation of the painting process is realized based on the multi-objective evaluation function. Effectiveness is verified by taking the outer plate above the waterline of a shipyard H1127/7 as the object. The results show that the performance of DBSCAN is significantly improved. Furthermore, the accurate classification of painting objects by RF is achieved. The experiment proves that the dry film thickness qualification rate obtained by the painting process designed by IDBSCAN-RF is 92.3%, which meets the requirements of the performance standard of protective coatings (PSPC).
      Citation: Coatings
      PubDate: 2021-11-28
      DOI: 10.3390/coatings11121458
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1459: A Fault Diagnosis Method Based on EEMD and
           Statistical Distance Analysis

    • Authors: Tingzhong Wang, Tingting Zhu, Lingli Zhu, Ping He
      First page: 1459
      Abstract: Serious vibration or wear with large friction usually appear when faults occur, which leads to more serious faults such as the destruction of the oil film, bringing great damages to both the society and economic sector. Therefore, the accurate diagnosis of a fault in the early stage is important for the safety operation of machinery. To effectively extract the fault features for diagnosis, EMD-based methods are widely used. However, these methods spend lots of efforts diagnosing faults and require plenty of professional knowledge of diagnosis. Although many intelligent classifiers can be used to automatically diagnose faults such as wear, a broken tooth and imbalance, the combing EMD-based method, the scarcity of samplings with labels hinder the application of these methods to engineering. It is because the model of the intelligent classifier must be constructed based on sufficient samplings with a label. To solve this problem, we propose a novel fault diagnosis method, which is performed based on the EEMD and statistical distance analysis. In this method, the EEMD is used to decompose one original signal into several IMFs and then the probability density distribution of each IMF is calculated. To diagnose the fault of the machinery, the Euclidean distance between the signal acquired under an unknown fault with the other referenced signals acquired previously under various fault types is calculated. At last, the fault of the signal is the same with the referenced signal when the distance is the smallest. To verify the effectiveness of our proposed method, a dataset of bearings with different faults, and a dataset of 2009 Prognostics and Health Management (PHM) data challenge, including gear, bearing and shaft faults are used. The result shows that the proposed method can not only automatically diagnose faults effectively, but also fewer samplings with a label are used compared with the intelligent methods.
      Citation: Coatings
      PubDate: 2021-11-28
      DOI: 10.3390/coatings11121459
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1460: Defect Formation Mechanism and Performance
           Study of Laser Cladding Ni/Mo Composite Coating

    • Authors: Min Sun, Ming Pang
      First page: 1460
      Abstract: In order to improve the wear resistance of Cu, a Ni/Mo composite coating was applied on the surface of Cu alloy by means of laser cladding. The laser power was 6000 W, the scanning speed was 5 mm/s and the feed rate was 10 g/min. The transition layer of the Ni layer had three layers, and the surface layer of the Mo layer had two layers. The results showed that the surface of the cladding layer was pure Mo. Due to the fluidity and non-equilibrium solidification of Mo in the molten state, pores and cracks along the grain boundary were observed in the Mo layer. The results showed that the cross-section of cladding layer was divided into a pure Mo layer, Mo-Ni-Cu mixed layer and an Ni-Cu mixed layer. The surface hardness of the Mo layer was 200~460 HV. Ni3Mo was formed at the interface of Mo and Ni. The hardness was improved by Ni3Mo; the maximum hardness was 750 HV. Under the same load and wear time, the wear rate of Cu was three times that of the surface layer.
      Citation: Coatings
      PubDate: 2021-11-28
      DOI: 10.3390/coatings11121460
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1461: Experimental Study and Mathematical
           Modeling of the Processes Occurring in ZrN Coating/Silumin Substrate
           Systems under Pulsed Electron Beam Irradiation

    • Authors: Nikolay N. Koval, Tamara V. Koval, Olga V. Krysina, Yurii F. Ivanov, Anton D. Teresov, Pavel V. Moskvin, My Kim An Tran, Nikita A. Prokopenko, Elizaveta A. Petrikova
      First page: 1461
      Abstract: This paper presents a study of a combined modification of silumin, which included deposition of a ZrN coating on a silumin substrate and subsequent treatment of the coating/substrate system with a submillisecond pulsed electron beam. The local temperature on the samples in the electron-beam-affected zone and the thickness of the melt zone were measured experimentally and calculated using a theoretical model. The Stefan problem was solved numerically for the fast heating of bare and ZrN-coated silumin under intense electron beam irradiation. Time variations of the temperature field, the position of the crystallization front, and the speed of the front movement have been calculated. It was found that when the coating thickness was increased from 0.5 to 2 μm, the surface temperature of the samples increased from 760 to 1070 °C, the rise rate of the surface temperature increased from 6 × 107 to 9 × 107 K/s, and the melt depth was no more than 57 μm. The speed of the melt front during the pulse was 3 × 105 µm/s. Good agreement was observed between the experimental and theoretical values of the temperature characteristics and melt zone thickness.
      Citation: Coatings
      PubDate: 2021-11-28
      DOI: 10.3390/coatings11121461
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1462: Advanced Binder-Free Electrode Based on
           CuCo2O4 Nanowires Coated with Polypyrrole Layer as a High-Performance
           Nonenzymatic Glucose Sensing Platform

    • Authors: Mohammad Rafe Hatshan, Sadia Aslam, Dmitry Bokov, Ahmed Jaber Ibrahim, Yasser Fakri Mustafa, Afshin Davarpanah, Marischa Elveny, Shafaqat Ali
      First page: 1462
      Abstract: In this work, the CuCo2O4 nanowires (CuCo2O4 NWs) were grown on carbon cloth electrode (CCE) and then coated with polypyrrole (pPy) layer (CuCo2O4 NWs-pPy@CCE). The morphology and structure characterization of as-prepared CuCo2O4 NWs-pPy@CCE were carried out using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), field-emission scanning electron microscope (FESEM), thermogravimetric analysis (TGA), and transmission electron microscope (TEM). The CuCo2O4 NWs-pPy@CCE was applied directly as an electrocatalyst toward nonenzymatic glucose oxidation. Due to the advantages of this 3D structure, it offer high availability to the analyte/electrolyte, abundant electrochemical-active sites, and high stability and conductivity. As a glucose sensor, the CuCo2O4 NWs-pPy@CCE shows wide linear range (0.01 to 21.3 mM), excellent sensitivity (4.41 μA μM−1 cm−2), good selectivity, low detection limit (0.2 μM), and rapid response time (<1 s) toward glucose detection. Furthermore, the designed sensor shows a great ability in detection of glucose in biological real samples.
      Citation: Coatings
      PubDate: 2021-11-28
      DOI: 10.3390/coatings11121462
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1463: Sustainable Manufacturing Process in the
           Context of Wood Processing by Sanding

    • Authors: Alena Očkajová, Martin Kučerka, Richard Kminiak, Adrián Banski
      First page: 1463
      Abstract: The aim of this paper is the issue of a sustainable manufacturing process in the context of woodworking by sanding, as one of the most important technological operations before its final treatment, focusing on a selected pillar of sustainable manufacturing process, waste management. The first step of the experiment was to optimize the pressures of the sanding means on the surface. The optimal pressure of 1.04 N·cm−2 was chosen. The second level was to obtain the wear curves of the abrasive means with grain size 80 (evaluated by wood removal) and the optimal pressure in dependence on the sanding direction (along and perpendicular to the wood fibres and in the direction of 60° to the wood fibres) and different types of woods (beech, oak, alder, pine). The set parameters were suitable for beech and were not suitable for alder and pine. By extending the operating life of the sanding belts via appropriate choice of input factor settings it can be influenced metrics of pillar waste management-savings of material and waste minimization.
      Citation: Coatings
      PubDate: 2021-11-28
      DOI: 10.3390/coatings11121463
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1464: Hybrid ZnO Flowers-Rods Nanostructure for
           Improved Photodetection Compared to Standalone Flowers and Rods

    • Authors: Abdullah M. Al-Enizi, Shoyebmohamad F. Shaikh, Asiya M. Tamboli, Afifa Marium, Muhammad Fazal Ijaz, Mohd Ubaidullah, Meera Moydeen Abdulhameed, Satish U. Ekar
      First page: 1464
      Abstract: Different Zinc Oxide (ZnO) morphologies have been used to improve photodetector efficiencies for optoelectronic applications. Herein, we present the very novel hybrid ZnO flower-rod (HZFR) morphology, to improve photodetector response and efficiency when compared to the prevalently used ZnO nanorods (NRs) and ZnO nanoflowers (NFs). The HZFR was fabricated via sol-gel microwave-assisted hydrothermal methods. HZFR achieves the benefits of both NFs, by trapping a greater amount of UV light for the generation of e-h pairs, and NRs, by effectively transporting the generated e-h pairs to the channel. The fabricated photosensors were characterized with scanning electron microscopy, X-ray diffraction, photoluminescence, and a Keithley 4200A-SCS parameter analyzer for their morphology, structural characteristics, optical performance, and electrical characteristics, respectively. The transient current response, current-voltage characteristics, and responsivity measurements were set as a benchmark of success to compare the sensor response of the three different morphologies. It was found that the novel HZFR showed the best UV sensor performance with the fastest response time (~7 s), the highest on-off ratio (52), and the best responsivity (126 A/W) when compared to the NRs and NFs. Hence, it was inferred that the HZFR morphology would be a great addition to the ZnO family for photodetector applications.
      Citation: Coatings
      PubDate: 2021-11-29
      DOI: 10.3390/coatings11121464
      Issue No: Vol. 11, No. 12 (2021)
       
  • Coatings, Vol. 11, Pages 1365: Evaluation of Properties and Mechanisms of
           Waste Plastic/Rubber-Modified Asphalt

    • Authors: Xiaorui Zhang, Chao Han, Frédéric Otto, Fan Zhang
      First page: 1365
      Abstract: Waste plastic, such as polyethylene (PE), and waste rubber tires, are pollutants that adversely affect the environment. Thus, the ways these materials are used are important in realizing the goals of reduced CO2 emissions and carbon neutrality. This paper investigates the fundamental properties, compatibility, and interaction mechanism of waste plastic/rubber-modified asphalt (WPRMA). Dynamic shear rheology, fluorescence microscopy, a differential scanning calorimeter, and molecular dynamic simulation software were used to evaluate the properties and mechanisms of WPRMA. The results show that the anti-rutting temperature of WPRMA with different waste plastic contents is higher than 60 °C and the optimal dosage of waste PE in WPRMA is 8%, which can enhance the high-temperature properties and compatibility of rubber-modified asphalt. The temperature can directly promote the melting and decomposition of the functional groups in WPRMA and thus must be strictly controlled during the mix production process. The interaction mechanism suggests that waste plastic can form networks and package the rubber particles in rubber-modified asphalt. The main force between waste plastic and rubber is Van der Waals force, which rarely occurs in chemical reactions.
      Citation: Coatings
      PubDate: 2021-11-07
      DOI: 10.3390/coatings11111365
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1366: Chitosan-Based Antimicrobial Coating for
           Improving Postharvest Shelf Life of Pineapple

    • Authors: Indra Bhusan Basumatary, Avik Mukherjee, Vimal Katiyar, Santosh Kumar, Joydeep Dutta
      First page: 1366
      Abstract: Rapid postharvest losses and quality deteriorations in pineapple are major challenges to growers and handlers. Chitosan-based coatings on fruit surfaces have gained importance in recent years to enhance postharvest shelf life of the fruits. In this study, aloe vera gel was added as a natural antioxidant in chitosan-based composite coating containing ZnO nanoparticles. The developed formulation was applied on the surface of freshly harvested pineapple fruits. ZnO nanoparticles were used as an antimicrobial agent. Coated pineapple fruits were evaluated for weight loss, total soluble solids, titratable acidity, decay index, maturity index, and sensory attributes, including visual appearance, periodically at 5 day interval during storage. The results showed that the coating of the fruit reduced weight loss by about 5%, and also delayed ripening and oxidative decay compared to the uncoated fruit. Thus, the developed coating formulation is a promising sustainable solution to reduce postharvest losses and to extend shelf life of pineapples.
      Citation: Coatings
      PubDate: 2021-11-08
      DOI: 10.3390/coatings11111366
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1367: Electrodeposition, Characterization, and
           Corrosion Behavior of CoCrFeMnNi High-Entropy Alloy Thin Films

    • Authors: Ana-Maria Julieta Popescu, Florina Branzoi, Ionut Constantin, Mihai Anastasescu, Marian Burada, Dumitru Mitrică, Ioana Anasiei, Mihai-Tudor Olaru, Virgil Constantin
      First page: 1367
      Abstract: Potentiostatic electrodeposition was used to obtain CoCrFeMnNi high-entropy alloy (HEA) thin films on copper substrate. An electrolyte based on a DMSO (dimethyl sulfoxide)-CH3CN (acetonitrile) organic compound was used for the HEA deposition. The microstructure of the high-entropy deposits before and after corrosion in artificial seawater was investigated by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) investigation. SEM analysis revealed that compact and uniform film consists of compact and uniform 50 nm–5 μm particles that form the HEA films. The successful co-deposition of all five elements was highlighted by the energy dispersive spectrometry investigation (EDS). Electrochemical measurements carried out in an aerated artificial seawater solution under ambient conditions demonstrated the promising potential for application in the field of anti-corrosion protection, due to the protective behavior of the HEA thin films.
      Citation: Coatings
      PubDate: 2021-11-08
      DOI: 10.3390/coatings11111367
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1368: Organic Thin Films Deposited by
           Matrix-Assisted Pulsed Laser Evaporation (MAPLE) for Photovoltaic Cell
           Applications: A Review

    • Authors: Marcela Socol, Nicoleta Preda, Gabriel Socol
      First page: 1368
      Abstract: Human society’s demand for energy has increased faster in the last few decades due to the world’s population growth and economy development. Solar power can be a part of a sustainable solution to this world’s energy need, taking into account that the cost of the renewable energy recently dropped owed to the remarkable progress achieved in the solar panels field. Thus, this inexhaustible source of energy can produce cheap and clean energy with a beneficial impact on the climate change. The considerable potential of the organic photovoltaic (OPV) cells was recently emphasized, with efficiencies exceeding 18% being achieved for OPV devices with various architectures. The challenges regarding the improvement in the OPV performance consist of the selection of the adequate raw organic compounds and manufacturing techniques, both strongly influencing the electrical parameters of the fabricated OPV devices. At the laboratory level, the solution-based techniques are used in the preparation of the active films based on polymers, while the vacuum evaporation is usually involved in the deposition of small molecule organic compounds. The major breakthrough in the OPV field was the implementation of the bulk heterojunction concept but the deposition of mixed films from the same solvent is not always possible. Therefore, this review provides a survey on the development attained in the deposition of organic layers based on small molecules compounds, oligomers and polymers using matrix-assisted pulsed laser evaporation (MAPLE)-based deposition techniques (MAPLE, RIR-MAPLE and emulsion-based RIR-MAPLE). An overview of the influence of various experimental parameters involved in these laser deposition methods on the properties of the fabricated layers is given in order to identify, in the forthcoming years, new strategies for enhancing the OPV cells performance.
      Citation: Coatings
      PubDate: 2021-11-08
      DOI: 10.3390/coatings11111368
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1369: New Approaches to Increasing the
           Superhydrophobicity of Coatings Based on ZnO and TiO2

    • Authors: Arsen E. Muslimov, Makhach Kh. Gadzhiev, Vladimir M. Kanevsky
      First page: 1369
      Abstract: The work presented is devoted to new approaches to increasing the superhydrophobic properties of coatings based on zinc oxide (ZnO) and titanium dioxide (TiO2). There is an innovation in the use of inorganic coatings with a non-polar structure, high melting point, and good adhesion to ZnO, in contrast to the traditionally used polymer coatings with low performance characteristics. The maximum superhydrophobicity of the ZnO surface (contact angle of 173°) is achieved after coating with a layer of hematite (Fe2O3). The reason for the abnormally high hydrophobicity is a combination of factors: minimization of the area of contact with water (Cassie state) and the specific microstructure of a coating with a layer of non-polar Fe2O3. It was shown that the coating of ZnO structures with bimodal roughness with a gold (Au) layer that is 60-nm thick leads to an increase in the wetting contact angle from 145° to 168°. For clean surfaces of Au and hematite Fe2O3 films, the contact angle wets at no more than 70°. In the case of titanium oxide coatings, what is new lies in the method of controlled synthesis of a coating with a given crystal structure and a level of doping with nitrogen using plasma technologies. It has been shown that the use of nitrogen plasma in an open atmosphere with different compositions (molecular, atomic) makes it possible to obtain both a hydrophilic (contact angle of 73°) and a highly hydrophobic surface (contact angle of 150°).
      Citation: Coatings
      PubDate: 2021-11-08
      DOI: 10.3390/coatings11111369
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1370: Soybean Oil Enriched with Antioxidants
           Extracted from Watermelon (Citrullus colocynthis) Skin Sap and Coated in
           Hydrogel Beads via Ionotropic Gelation

    • Authors: Muhammad Farooq, Elham Azadfar, Monica Trif, Ramezan Ali Jabaleh, Alexandru Rusu, Zohre Bahrami, Mahniya Sharifi, Sneh Punia Bangar, Naila Ilyas, Bianca Eugenia Ștefănescu, Yunyang Wang
      First page: 1370
      Abstract: Many plants and fruits are rich in antioxidant and antimicrobial compounds, such as phenolic compounds. Watermelon is one example, as various parts of the fruit present interesting phytochemical profiles. This study demonstrates that a natural C. colocynthis (watermelon) (W) skin sap (SS) extract can effectively improve the oxidative stability of microencapsulated soybean (SB) oil. By employing a combination of alginate–xanthan gums (AXG) in a matrix hydrogel bead model with WSS extract, high encapsulation efficiency can be obtained (86%). The effects of process variables on the ultrasound-assisted extraction (UAE) of phenolic compounds from watermelon (W) skin sap (SS) using the response surface methodology (RSM), as an optimized and efficient extraction process, are compared with the effects of a conventional extraction method, namely the percolation method. The WSS extracts are obtained via UAE and RSM or the conventional percolation extraction method. The two obtained extracts and synthetic antioxidant butylated hydroxytolune (BHT) are added to SB oil separately and their antioxidant effects are tested and compared. The results show the improved oxidative stability of SB oil containing the extract obtained via the optimized method (20–30%) compared to the SB oil samples containing extract obtained via the percolation extraction method, synthetic antioxidant (BHT), and SB oil only as the control (no antioxidant added). According to existing studies, we assume that the use of WSS as an effective antioxidant will ensure the prolonged stability of encapsulated SB oil in hydrogel beads, as it is well known that extended storage under different conditions may lead to severe lipid oxidation.
      Citation: Coatings
      PubDate: 2021-11-08
      DOI: 10.3390/coatings11111370
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1371: Microencapsulation for Functional Textile
           Coatings with Emphasis on Biodegradability—A Systematic Review

    • Authors: Bojana Boh Podgornik, Stipana Šandrić, Mateja Kert
      First page: 1371
      Abstract: The review provides an overview of research findings on microencapsulation for functional textile coatings. Methods for the preparation of microcapsules in textiles include in situ and interfacial polymerization, simple and complex coacervation, molecular inclusion and solvent evaporation from emulsions. Binders play a crucial role in coating formulations. Acrylic and polyurethane binders are commonly used in textile finishing, while organic acids and catalysts can be used for chemical grafting as crosslinkers between microcapsules and cotton fibres. Most of the conventional coating processes can be used for microcapsule-containing coatings, provided that the properties of the microcapsules are appropriate. There are standardised test methods available to evaluate the characteristics and washfastness of coated textiles. Among the functional textiles, the field of environmentally friendly biodegradable textiles with microcapsules is still at an early stage of development. So far, some physicochemical and physical microencapsulation methods using natural polymers or biodegradable synthetic polymers have been applied to produce environmentally friendly antimicrobial, anti-inflammatory or fragranced textiles. Standardised test methods for evaluating the biodegradability of textile materials are available. The stability of biodegradable microcapsules and the durability of coatings during the use and care of textiles still present several challenges that offer many opportunities for further research.
      Citation: Coatings
      PubDate: 2021-11-09
      DOI: 10.3390/coatings11111371
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1372: Multi-Analytical Research on the Caisson
           Painting of Dayu Temple in Hancheng, Shaanxi, China

    • Authors: Jiaxin Li, Bingjie Mai, Peng Fu, Gele Teri, Yanli Li, Jing Cao, Yuhu Li, Juanli Wang
      First page: 1372
      Abstract: In this research, the caisson painting of Dayu Temple in Hancheng, Shaanxi, China, was analyzed via a multi-analytical methodology, using a pH meter, an ultra-depth-of-field optical microscope, a scanning electron microscope-energy dispersive spectrometer (SEM-EDS), a high-resolution X-ray diffractometer (XRD), a micro-confocal laser Raman spectrometer, a gas chromatography mass spectrometer (GC-MS), and X-ray fluorescence spectroscopy (XRF). With the corroborative evidence derived from the above analyses, it could be determined that the caisson painting of Dayu Temple was painted on bamboo paper and attached to hemlock wood substrate of the Pinaceae Tsuga genus using starch paste, with common colorants such as carbon black, cinnabar mixed with a small amount of red lead, ultramarine, and ultramarine mixed with Paris green, with animal glue having been adopted as a sizing agent. These results provide important scientific data for the production craft of precious caisson paintings, contributing to the revelation of their historic, artistic, and scientific value, and should enable conservators to make informed decisions in restoration.
      Citation: Coatings
      PubDate: 2021-11-09
      DOI: 10.3390/coatings11111372
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1373: Microstructure and Oxidation Behavior of
           Nb-Si-Based Alloys for Ultrahigh Temperature Applications: A Comprehensive
           Review

    • Authors: Fuqiang Shen, Yingyi Zhang, Laihao Yu, Tao Fu, Jie Wang, Hong Wang, Kunkun Cui
      First page: 1373
      Abstract: Nb-Si-based superalloys are considered as the most promising high-temperature structural material to replace the Ni-based superalloys. Unfortunately, the poor oxidation resistance is still a major obstacle to the application of Nb-Si-based alloys. Alloying is a promising method to overcome this problem. In this work, the effects of Hf, Cr, Zr, B, and V on the oxidation resistance of Nb-Si-based superalloys were discussed. Furthermore, the microstructure, phase composition, and oxidation characteristics of Nb-Si series alloys were analyzed. The oxidation reaction and failure mechanism of Nb-Si-based alloys were summarized. The significance of this work is to provide some references for further research on high-temperature niobium alloys.
      Citation: Coatings
      PubDate: 2021-11-09
      DOI: 10.3390/coatings11111373
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1374: Green Synthesis of Metal and Metal Oxide
           Nanoparticles Using Different Plants’ Parts for Antimicrobial Activity
           and Anticancer Activity: A Review Article

    • Authors: Aysha Bukhari, Irfan Ijaz, Ezaz Gilani, Ammara Nazir, Hina Zain, Ramsha Saeed, Saleh S. Alarfaji, Sajjad Hussain, Rizwana Aftab, Yasra Naseer
      First page: 1374
      Abstract: Nanotechnology emerged as a scientific innovation in the 21st century. Metallic nanoparticles (metal or metal oxide nanoparticles) have attained remarkable popularity due to their interesting biological, physical, chemical, magnetic, and optical properties. Metal-based nanoparticles can be prepared by utilizing different biological, physical, and chemical methods. The biological method is preferred as it provides a green, simple, facile, ecofriendly, rapid, and cost-effective route for the green synthesis of nanoparticles. Plants have complex phytochemical constituents such as carbohydrates, amino acids, phenolics, flavonoids, terpenoids, and proteins, which can behave as reducing and stabilizing agents. However, the mechanism of green synthesis by using plants is still highly debatable. In this report, we summarized basic principles or mechanisms of green synthesis especially for metal or metal oxide (i.e., ZnO, Au, Ag, and TiO2, Fe, Fe2O3, Cu, CuO, Co) nanoparticles. Finally, we explored the medical applications of plant-based nanoparticles in terms of antibacterial, antifungal, and anticancer activity.
      Citation: Coatings
      PubDate: 2021-11-09
      DOI: 10.3390/coatings11111374
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1375: Numerical Study on the Impact of Gap
           between Sheets on the Quality of Riveted Single-Strap Butt Joints

    • Authors: Zhenzheng Ke, Yongliang Zhang, Yuchi Liu, Zhengwei Zhong, Chunrun Zhu, Yunbo Bi
      First page: 1375
      Abstract: Some controllable process parameters in the riveting process such as the gap between sheets, have an important impact on the quality of a riveted butt joint. In this paper, the finite element model of a riveted single-strap butt joint is established with the help of ABAQUS analysis software, and the riveting process is simulated under five kinds of gaps between sheets. From the perspectives of rivet upsetting size, rivet interference, radial deformation of sheet, and analysis of residual stress around the hole of sheet, the influence of the gap between sheets on the connection quality of the riveted butt joint is summarized. The results show that the left and right sheets will contact each other and there is extrusion stress between the sheets when the gap is zero. When the applied tensile load continues to increase, due to the influence of the secondary bending, the strap sheet responsible for the connection produces warping deformation, and there will be no further contact between the sheets. When the gap between sheets increases from 0 to 2 mm, the maximum deformation of strap sheets increases from 0.876 to 0.927 mm, which proves that the gap between sheets have no significant effect on the deformation of the strap sheet.
      Citation: Coatings
      PubDate: 2021-11-10
      DOI: 10.3390/coatings11111375
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1376: Morphological and Structural Evolution of
           Chemically Deposited Epitaxially LaNiO3 Thin Films

    • Authors: Mircea Nasui, Ramona Bianca Sonher, Ecaterina Ware, Andrada Daniel, Traian Petrisor, Mihai Sebastian Gabor, Lelia Ciontea, Traian Petrisor
      First page: 1376
      Abstract: We report the preparation and characterization of epitaxial LaNiO3 (LNO) thin films by chemical solution deposition method using lanthanum and nickel acetylacetonates as starting reagents dissolved in propionic acid. In order to obtain further information regarding the decomposition behavior of the film, the precursor solution was dried to obtain the precursor powder, which was investigated by thermal analyses and X-ray diffraction measurements (XRD). The LNO perovskite thin films were deposited by spin coating on SrTiO3(100) single crystal substrates. A detailed study with different crystallization temperatures (600–900 °C) at two different heating ramps (5 and 10 °C/min) was performed. Oriented LaNiO3 thin films with good out-of-plane textures were obtained with optimal surface morphologies.
      Citation: Coatings
      PubDate: 2021-11-10
      DOI: 10.3390/coatings11111376
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1377: Impacting Droplet Can Mitigate Dust from
           PDMS Micro-Post Array Surfaces

    • Authors: Abba Abdulhamid Abubakar, Bekir Sami Yilbas, Mubarak Yakubu, Hussain Al-Qahtani, Ghassan Hassan, Johnny Ebaika Adukwu
      First page: 1377
      Abstract: In this paper, the impact mechanisms of a water droplet on hydrophobized micro-post array surfaces are examined and the influence of micro-post arrays spacing on the droplet behavior in terms of spreading, retraction, and rebounding is investigated. Impacting droplet behavior was recorded using a high-speed facility and flow generated in the droplet fluid was simulated in 3D geometry accommodating conditions of the experiments. Micro-post arrays were initially formed lithographically on silicon wafer surfaces and, later, replicated by polydimethylsiloxane (PDMS). The replicated micro-post arrays surfaces were hydrophobized through coating by functionalized nano-silica particles. Hydrophobized surfaces result in a contact angle of 153° ± 3° with a hysteresis of 3° ± 1°. The predictions of the temporal behavior of droplet wetting diameter during spreading agree with the experimental data. Increasing micro-post arrays spacing reduces the maximum spreading diameter on the surface; in this case, droplet fluid penetrated micro-posts spacing creates a pinning effect while lowering droplet kinetic energy during the spreading cycle. Flow circulation results inside the droplet fluid in the edge region of the droplet during the spreading period; however, opposing flow occurs from the outer region towards the droplet center during the retraction cycle. This creates a stagnation zone in the central region of the droplet, which extends towards the droplet surface onset of droplet rebounding. Impacting droplet mitigates dust from hydrophobized micro-post array surfaces, and increasing droplet Weber number increases the area of dust mitigated from micro-post arrays surfaces.
      Citation: Coatings
      PubDate: 2021-11-10
      DOI: 10.3390/coatings11111377
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1378: Properties of Spark Plasma Sintered
           Compacts and Magnetron Sputtered Coatings Made from Cr, Mo, Re and Zr
           Alloyed Tungsten Diboride

    • Authors: Tomasz Mościcki, Rafał Psiuk, Joanna Radziejewska, Maria Wiśniewska, Dariusz Garbiec
      First page: 1378
      Abstract: To enhance the properties of tungsten diboride, we have synthesized and characterized solid solutions of this material with chromium, molybdenum, rhenium and zirconium. The obtained materials were subsequently deposited as coatings. Various concentrations of these transition metal elements, ranging from 0.0 to 24.0 at.%, on a metals basis, were made. Spark plasma sintering was used to synthesize these refractory compounds from the pure elements. Elemental and phase purity of both samples (sintered compacts and coatings) were examined using energy dispersive X-ray spectroscopy and X-ray diffraction. Microindentation was utilized to measure the Vickers hardness. X-ray diffraction results indicate that the solubility limit is below 8 at.% for Mo, Re and Zr and below 16 at.% for Cr. Above this limit both diborides (W,TM)B2 are created. Addition of transition metals caused decrease of density and increase of hardness and electrical conductivity of sintered compacts. Deposited coatings W1−xTMxBy (TM = Cr, Mo, Re, Zr; x = 0.2; y = 1.7–2) are homogenous, smooth and hard. The maximal hardness was measured for W-Cr-B films and under the load of 10 g was 50.4 ± 4.7 GPa. Deposited films possess relatively high fracture toughness and for WB2 coatings alloyed with zirconium it is K1c = 2.11 MPa m1/2.
      Citation: Coatings
      PubDate: 2021-11-10
      DOI: 10.3390/coatings11111378
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1379: Green Coating Polymers in Meat Preservation

    • Authors: Mohammed Gagaoua, Tanima Bhattacharya, Melisa Lamri, Fatih Oz, Amira Leila Dib, Emel Oz, Ilke Uysal-Unalan, Igor Tomasevic
      First page: 1379
      Abstract: Edible coatings, including green polymers are used frequently in the food industry to improve and preserve the quality of foods. Green polymers are defined as biodegradable polymers from biomass resources or synthetic routes and microbial origin that are formed by mono- or multilayer structures. They are used to improve the technological properties without compromising the food quality, even with the purpose of inhibiting lipid oxidation or reducing metmyoglobin formation in fresh meat, thereby contributing to the final sensory attributes of the food and meat products. Green polymers can also serve as nutrient-delivery carriers in meat and meat products. This review focuses on various types of bio-based biodegradable polymers and their preparation techniques and applications in meat preservation as a part of active and smart packaging. It also outlines the impact of biodegradable polymer films or coatings reinforced with fillers, either natural or synthesized, via the green route in enhancing the physicochemical, mechanical, antimicrobial, and antioxidant properties for extending shelf-life. The interaction of the package with meat contact surfaces and the advanced polymer composite sensors for meat toxicity detection are further considered and discussed. In addition, this review addresses the research gaps and challenges of the current packaging systems, including coatings where green polymers are used. Coatings from renewable resources are seen as an emerging technology that is worthy of further investigation toward sustainable packaging of food and meat products.
      Citation: Coatings
      PubDate: 2021-11-10
      DOI: 10.3390/coatings11111379
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1380: Fabrication of a UV Photodetector Based on
           n-TiO2/p-CuMnO2 Heterostructures

    • Authors: Mircea Nicolaescu, Cornelia Bandas, Corina Orha, Viorel Şerban, Carmen Lazău, Simona Căprărescu
      First page: 1380
      Abstract: The heterojunction based on n-TiO2 nanolayer/p-CuMnO2 thin film was achieved using an efficient two-step synthesis process for the fabrication of a UV photodetector. The first step consisted of obtaining the TiO2 nanolayer, which was grown on titan foil by thermal oxidation (Ti-TiO2). The second step consisted of CuMnO2 thin film deposition onto the surface of Ti-TiO2 using the Doctor Blade method. Techniques such as X-ray diffraction, UV-VIS analysis, SEM, and AFM morphologies were used for the investigation of the structural and morphological characteristics of the as-synthesized heterostructures. The Mott–Schottky analysis was performed in order to prove the n-TiO2/p-CuMnO2 junction. The I-V measurements of the n-TiO2 nanolayer/p-CuMnO2 thin film heterostructure confirm its diode characteristics under dark state, UV and visible illumination conditions. The obtained heterojunction, which is based on two types of semiconductors with different energy band structures, improves the separating results of charges, which is very important for high-performance UV photodetectors.
      Citation: Coatings
      PubDate: 2021-11-11
      DOI: 10.3390/coatings11111380
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1381: Effect of HfO2-Based Multi-Dielectrics on
           Electrical Properties of Amorphous In-Ga-Zn-O Thin Film Transistors

    • Authors: Ruozheng Wang, Qiang Wei, Jie Li, Jiao Fu, Yiwei Liu, Tianfei Zhu, Cui Yu, Gang Niu, Shengli Wu, Hongxing Wang
      First page: 1381
      Abstract: We report the fabrication of bottom gate a-IGZO TFTs based on HfO2 stacked dielectrics with decent electrical characteristics and bias stability. The microscopic, electrical, and optical properties of room temperature deposited a-IGZO film with varied oxygen content were explored. In order to suppress the bulk defects in the HfO2 thin film and hence maximize the quality, surface modification of the SiNx film was investigated so as to achieve a more uniform layer. The root mean square (RMS) roughness of SiNx/HfO2/SiNx (SHS) stacked dielectrics was only 0.66 nm, which was reduced by 35% compared with HfO2 single film (1.04 nm). The basic electrical characteristics of SHS-based a-IGZO TFT were as follows: Vth is 2.4 V, μsat is 21.1 cm2 V−1 s−1, Ion/Ioff of 3.3 × 107, Ioff is 10−11 A, and SS is 0.22 V/dec. Zr-doped HfO2 could form a more stable surface, which will decrease the bulk defect states so that the stability of device can be improved. It was found that the electrical characteristics were improved after Zr doping, with a Vth of 1.4 V, Ion/Ioff of 108, μsat of 19.5 cm2 V−1 s−1, Ioff of 10−12 A, SS of 0.18 V/dec. After positive gate bias stress of 104 s, the ΔVth was decreased from 0.43 V (without Zr doping) to 0.09 V (with Zr doping), the ΔSS was decreased from 0.19 V/dec to 0.057 V/dec, respectively, which shows a meaningful impact to realize the long-term working stability of TFT devices.
      Citation: Coatings
      PubDate: 2021-11-11
      DOI: 10.3390/coatings11111381
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1382: Clinical Application of Silver
           Nanoparticles Coated by Benzalkonium Chloride

    • Authors: Shakeel Ahmed Ansari, Asim Muhammed Alshanberi
      First page: 1382
      Abstract: The present study investigates the surface modification of AgNPs (synthesized by neem leaves) by benzalkonium chloride (BAC). It was observed that 22 × 109 CFU were formed at 0.25 mM AgNPs concentration. However, it was reduced to 14 × 109 CFU for BAC-coated AgNPs at similar experimental conditions. The enzymatic activity of β-glucosidase was significantly enhanced from 0.0625 mM to 0.5 mM concentration of AgNPs, as well as BAC–AgNPs. However, there was no further change of activity beyond this concentration. ZOI of AgNPs and BAC–AgNPs was measured against E. coli, B. subtilis, P. aeruginosa, and S pneumoniae at 0.25 mM and 0.50 mM concentrations of these bioactive agents. ZOI was 3.45 cm and 3.56 cm for AgNPs and BAC–AgNPs at 0.25 mM of these bioactive agents, respectively, against E. coli. However, these values were 4.28 cm and 4.40 cm, respectively, against B. subtilis. ZOI was obtained at 3.36 cm and 3.47 cm, respectively, against P. aeruginosa under similar experimental concentrations. However, ZOI was achieved at 3.44 cm and 3.62 cm, respectively, against S. pneumonia, under similar experimental conditions. Hence, such research findings can be exploited for potential applications in numerous environmental and biomedical fields.
      Citation: Coatings
      PubDate: 2021-11-11
      DOI: 10.3390/coatings11111382
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1383: Functionality of Films from Nigella sativa
           Defatted Seed Cake Proteins Plasticized with Grape Juice: Use in Wrapping
           Sweet Cherries

    • Authors: Dana Yaseen, Mohammed Sabbah, Asmaa Al-Asmar, Mohammad Altamimi, Michela Famiglietti, C. Valeria L. Giosafatto, Loredana Mariniello
      First page: 1383
      Abstract: The main aim of this work is to improve the functionality of Nigella sativa protein concentrate (NSPC) films by using grape juice (GJ). The film’s mechanical, antioxidant, and antimicrobial activities were evaluated. The obtained results showed, for the first time, that GJ at concentrations of 2%–10% (v/v) are able to act as plasticizer for the NSPC films with promising film properties. The results showed that the tensile strength and Young’s modulus of NSPC films were reduced significantly when the GJ increased. However, the NSPC films prepared with 6% GJ observed a higher elongation at break compared with other films. Moreover, the obtained films showed very interesting and promising results for their antioxidant and antimicrobial properties compared with the control films. The sweet cherries wrapped with NSPC film showed that the TSS (Brix) was significantly lower compared to the control, after 10 days of storage. However, the titratable acidity, pH value, and L* of all cherries, either wrapped or not, was not significantly different in all storage times. On the other hand, hue angle was significantly lower after 10 days of storage at −18 °C compared with control films. GJ has a multi-functional effect for protein-based films as plasticizer, antioxidant, and antimicrobial function.
      Citation: Coatings
      PubDate: 2021-11-12
      DOI: 10.3390/coatings11111383
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1384: Comprehensive Enhancement of Mechanical,
           Water-Repellent and Antimicrobial Properties of Regenerated Seaweed and
           Plant-Based Paper with Chitosan Coating

    • Authors: Rabi Ibrahim Saleh, Mirae Kim, Chaenyung Cha
      First page: 1384
      Abstract: Regenerated papers made from discarded natural sources, such as seaweeds or non-wood plants, are viewed as promising eco-friendly alternatives relative to conventional wood-based paper. However, due to its limited mechanical strength and higher water absorption than compared to traditional wood paper, it often results in premature structural disintegration. In order to overcome this limitation, this research introduces an efficient and comprehensive strategy of coating seaweed and plant papers with varying concentrations and molecular weights of chitosan. Increased concentration and molecular weight resulted in a greater amount of chitosan deposition, while the highest molecular weight also shows increased dissolution of soluble components of the paper. Since plants and seaweeds contain high anionic polysaccharide contents, the cationic chitosan shows high binding affinity towards paper. The resulting chitosan-coated papers demonstrate significant enhancements in water repellency and mechanical properties. In addition, the chitosan-coated papers also show significant bacterial inhibition effects due to the natural anti-microbial activity of chitosan.
      Citation: Coatings
      PubDate: 2021-11-12
      DOI: 10.3390/coatings11111384
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1385: Polydopamine-Assisted Surface Modification
           of Ti-6Al-4V Alloy with Anti-Biofilm Activity for Dental Implantology
           Applications

    • Authors: Ioana Cristina Marinas, Bianca Maria Tihauan, Andreea Gabriela Diaconu, Xenia Filip, Anca Petran, Ioana-Georgeta Grosu, Diana Bogdan, Lucian Barbu, Ana Maria Ivanof, Marin Angheloiu, Gratțiela Gradisteanu Pircalabioru, Claudiu Filip
      First page: 1385
      Abstract: Coating the surfaces of implantable materials with various active principles to ensure inhibition of microbial adhesion, is a solution to reduce infections associated with dental implant. The aim of the study was to optimize the polydopamine films coating on the Ti-6Al-6V alloy surface in order to obtain a maximum of antimicrobial/antibiofilm efficacy and reduced cytotoxicity. Surface characterization was performed by evaluating the morphology (SEM, AFM) and structures (Solid-state 13C NMR and EPR). Antimicrobial activity was assessed by logarithmic reduction of CFU/mL, and the antibiofilm activity by reducing the adhesion of Escherichia coli, Staphylococcus aureus, and Candida albicans strains. The release of NO was observed especially for C. albicans strain, which confirms the results obtained for microbial adhesion. Among the PDA coatings, for 0.45:0.88 (KMnO4:dopamine) molar ratio the optimal compromise was obtained in terms of antimicrobial activity and cytotoxicity, while the 0.1:1.5 ratio (KMnO4:dopamine) led to higher NO release and implicitly the reduction of the adhesion capacities only for C. albicans, being slightly cytotoxic but with moderate release of LDH. The proposed materials can be used to reduce the adhesion of yeast to the implantable material and thus inhibit the formation of microbial biofilms.
      Citation: Coatings
      PubDate: 2021-11-12
      DOI: 10.3390/coatings11111385
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1386: Bioactive Glass—An Extensive Study of the
           Preparation and Coating Methods

    • Authors: Maxim Maximov, Oana-Cristina Maximov, Luminita Craciun, Denisa Ficai, Anton Ficai, Ecaterina Andronescu
      First page: 1386
      Abstract: Diseases or complications that are caused by bone tissue damage affect millions of patients every year. Orthopedic and dental implants have become important treatment options for replacing and repairing missing or damaged parts of bones and teeth. In order to use a material in the manufacture of implants, the material must meet several requirements, such as mechanical stability, elasticity, biocompatibility, hydrophilicity, corrosion resistance, and non-toxicity. In the 1970s, a biocompatible glassy material called bioactive glass was discovered. At a later time, several glass materials with similar properties were developed. This material has a big potential to be used in formulating medical devices, but its fragility is an important disadvantage. The use of bioactive glasses in the form of coatings on metal substrates allows the combination of the mechanical hardness of the metal and the biocompatibility of the bioactive glass. In this review, an extensive study of the literature was conducted regarding the preparation methods of bioactive glass and the different techniques of coating on various substrates, such as stainless steel, titanium, and their alloys. Furthermore, the main doping agents that can be used to impart special properties to the bioactive glass coatings are described.
      Citation: Coatings
      PubDate: 2021-11-13
      DOI: 10.3390/coatings11111386
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1387: Surface Topography of PVD Hard Coatings

    • Authors: Peter Panjan, Aljaž Drnovšek, Nastja Mahne, Miha Čekada, Matjaž Panjan
      First page: 1387
      Abstract: The primary objective of this study was to investigate and compare the surface topography of hard coatings deposited by three different physical vapor deposition methods (PVD): low-voltage electron beam evaporation, unbalanced magnetron sputtering and cathodic arc evaporation. In these deposition systems, various ion etching techniques were applied for substrate cleaning. The paper summarizes our experience and the expertise gained during many years of development of PVD hard coatings for the protection of tools and machine components. Surface topography was investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM), scanning transmission electron microscopy (STEM) and 3D stylus profilometry. Observed similarities and differences among samples deposited by various deposition methods are discussed and correlated with substrate material selection, substrate pretreatment and deposition conditions. Large variations in the surface topography were observed between selected deposition techniques, both after ion etching and deposition processes. The main features and implications of surface cleaning by ion etching are discussed and the physical phenomena involved in this process are reviewed. During a given deposition run as well as from one run to another, a large spatial variation of etching rates was observed due to the difference in substrate geometry and batching configurations. Variations related to the specific substrate rotation (i.e., temporal variations in the etching and deposition) were also observed. The etching efficiency can be explained by the influence of different process parameters, such as substrate-to-source orientation and distance, shadowing and electric field effects. The surface roughness of PVD coatings mainly originates from growth defects (droplets, nodular defects, pinholes, craters, etc.). We briefly describe the causes of their formation.
      Citation: Coatings
      PubDate: 2021-11-13
      DOI: 10.3390/coatings11111387
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1388: Prediction of Coating Adhesion on
           Laser-Cleaned Metal Surfaces of Battery Cells Using Hyperspectral Imaging
           and Machine Learning

    • Authors: Johannes Maximilian Vater, Florian Gruber, Wulf Grählert, Sebastian Schneider, Alois Christian Knoll
      First page: 1388
      Abstract: Electric vehicles are shaping the future of the automotive industry. The traction battery is one of the most important components of electric cars. To ensure that the battery operates safely, it is essential to physically and electrically separate the cells facing each other. Coating a cell with varnish helps achieve this goal. Current studies use a destructive method on a sampling basis, the cross-cut test, to investigate the coating quality. In this paper, we present a fast, nondestructive and inline alternative based on hyperspectral imaging and artificial intelligence. Therefore, battery cells are measured with hyperspectral cameras in the visible and near-infrared (VNIR and NIR) parts of the electromagnetic spectrum before and after cleaning then coated and finally subjected to cross-cut test to estimate coating adhesion. During the cross-cut test, the cell coating is destroyed. This work aims to replace cross-cut tests with hyperspectral imaging (HSI) and machine learning to achieve continuous quality control, protect the environment, and save costs. Therefore, machine learning models (logistic regression, random forest, and support vector machines) are used to predict cross-cut test results based on hyperspectral data. We show that it is possible to predict with an accuracy of ~75% whether problems with coating adhesion will occur. Hyperspectral measurements in the near-infrared part of the spectrum yielded the best results. The results show that the method is suitable for automated quality control and process control in battery cell coating, but still needs to be improved to achieve higher accuracies.
      Citation: Coatings
      PubDate: 2021-11-14
      DOI: 10.3390/coatings11111388
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1389: Sol–Gel Encapsulation of ZnAl Alloy
           Powder with Alumina Shell

    • Authors: David Svetlizky, Noam Eliaz
      First page: 1389
      Abstract: Additive manufacturing (AM), for example, directed energy deposition (DED), may allow the processing of self-healing metal–matrix composites (SHMMCs). The sealing of cracks in these SHMMCs would be achieved via the melting of micro-encapsulated low melting point particulates (LMPPs), incorporated into the material during AM, by heat treatment of the part during service. Zn-Al alloys are good candidates to serve as LMPPs, for example, when the matrix of the MMC is made of an aluminum alloy. However, such powders should first be encapsulated by a thermal and diffusion barrier. Here, we propose a sol–gel process for encapsulation of a custom-made ZA-8 (Zn92Al8, wt.%) core powder in a ceramic alumina (Al2O3) shell. We first modify the surface of the ZA-8 powder with (12-phosphonododecyl)phosphonic acid (Di-PA) hydrophobic self-assembled monolayer (SAM) in order to prevent extensive hydrogen evolution and formation of non-uniform and porous oxide/hydroxide surface layers during the sol–gel process. Calcination for 1 h at 500 °C is found to be insufficient for complete boehmite-to-γ(Al2O3) phase transformation. Thermal stability tests in an air-atmosphere furnace at 600 °C for 1 h result in melting, distortion, and sintering into a brittle sponge (aggregate) of the as-atomized powder. In contrast, the core/shell powder is not sintered and preserves its spherical morphology, with no apparent “leaks” of the ZA-8 core alloy out of the ceramic encapsulation.
      Citation: Coatings
      PubDate: 2021-11-14
      DOI: 10.3390/coatings11111389
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1390: Analytical Model of the Process of Thermal
           Barrier Coating by the MO CVD Method

    • Authors: Vladimir V. Lukashov, Asiya E. Turgambaeva, Igor K. Igumenov
      First page: 1390
      Abstract: Integral regularities in the growth of 7YSZ thermal barrier coatings during MO CVD (Metal–Organic Chemical Vapor Deposition) are proposed. Within the framework of the model of the reacting boundary layer, the coating deposition process is considered as a process of independent global reactions of diffusion combustion of Zr(dpm)4 and Y(dpm)3 under convection conditions on a permeable surface. The rate of coating growth and the efficiency of using a precursor are analytically evaluated. The correctness of the proposed approach is confirmed by comparison with known experimental data. The considered model can be used to analyze the deposition of coatings from various mixtures of precursors, such as Nd(dpm)3, Hf(dpm)4, and Sm(dpm)3.
      Citation: Coatings
      PubDate: 2021-11-15
      DOI: 10.3390/coatings11111390
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1391: Effects of Drying Temperature and Molar
           Concentration on Structural, Optical, and Electrical Properties of
           β-Ga2O3 Thin Films Fabricated by Sol–Gel Method

    • Authors: Taejun Park, Kyunghwan Kim, Jeongsoo Hong
      First page: 1391
      Abstract: In this study, β-Ga2O3 films were fabricated on a quartz substrate by the sol–gel method using different drying temperatures and solutions of different molar concentrations, and their structural, optical, and electrical properties were evaluated. The as-fabricated films exhibited a monoclinic β-Ga2O3 crystal structure, whose crystallinity and crystallite size increased with increasing molar concentration of the solutions used and increasing drying temperature. Scanning electron microscopy of the as-prepared samples revealed dense surface morphologies and that the thickness of the films also depended on the deposition conditions. The average transmittance of all the samples was above 8% in visible light, and the calculated optical bandgap energy was 4.9 eV. The resistivity measured using a 4-point probe system was 3.7 × 103 Ω cm.
      Citation: Coatings
      PubDate: 2021-11-15
      DOI: 10.3390/coatings11111391
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1392: Structural and Optical Properties of CuO
           Thin Films Synthesized Using Spray Pyrolysis Method

    • Authors: Oleksii Diachenko, Jaroslav Kováč, Oleksandr Dobrozhan, Patrik Novák, Jaroslav Kováč, Jaroslava Skriniarova, Anatoliy Opanasyuk
      First page: 1392
      Abstract: Copper oxide thin films were obtained using pulsating spray pyrolysis method. The morphological, structural, and optical properties of fabricated films were studied. X-ray analysis revealed that the CuO thin films are single-phase. The study of films morphology by SEM and AFM methods showed that the obtained films have a fairly high surface roughness and contain grains of different shapes and sizes. It was found that the obtained films of copper oxide have high values of the absorption coefficient, which confirms the possibility of their use as absorbing layers for solar cells. The obtained values of the optical band gap of the material are in the range from 1.45 eV to 1.60 eV. Raman spectroscopy revealed three modes A1g, B1g, and B2g, of the crystal structure of monoclinic CuO. The devices based on p-type copper oxide are promising for solar cells fabrication because they can reduce production costs, due to their low cost and inexpensive production methods compared to silicon solar cells fabrication.
      Citation: Coatings
      PubDate: 2021-11-15
      DOI: 10.3390/coatings11111392
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1393: Bioactive Edible Films and Coatings Based
           in Gums and Starch: Phenolic Enrichment and Foods Application

    • Authors: Sónia Pedreiro, Artur Figueirinha, Ana Sanches Silva, Fernando Ramos
      First page: 1393
      Abstract: Edible films and coatings allow preserving fresh and processed food, maintaining quality, preventing microbial contamination and/or oxidation reactions and increasing the shelf life of food products. The structural matrix of edible films and coatings is mainly constituted by proteins, lipids or polysaccharides. However, it is possible to increase the bioactive potential of these polymeric matrices by adding phenolic compounds obtained from plant extracts. Phenolic compounds are known to possess several biological properties such as antioxidant and antimicrobial properties. Incorporating phenolic compounds enriched plant extracts in edible films and coatings contribute to preventing food spoilage/deterioration and the extension of shelf life. This review is focused on edible films and coatings based on gums and starch. Special attention is given to bioactive edible films and coatings incorporating plant extracts enriched in phenolic compounds.
      Citation: Coatings
      PubDate: 2021-11-15
      DOI: 10.3390/coatings11111393
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1394: Microfluidic Simulation and Optimization of
           Blood Coagulation Factors and Anticoagulants in Polymethyl Methacrylate
           Microchannels

    • Authors: Philip Nathaniel Immanuel, Yi-Hsiung Chiu, Song-Jeng Huang
      First page: 1394
      Abstract: Blood coagulation is a critical and complex reaction that involves various chemical substances, such as prothrombin, fibrinogen, and fibrin. The process can be divided into three main steps, namely the formation of the prothrombin activator, conversion of prothrombin to thrombin, and conversion of fibrinogen to fibrin. In this study, an ANSYS simulation is carried out to determine the prothrombin time (PT) of blood, the chemical changes that occur during coagulation and the anticoagulation factor. The addition of deionized water to the microchannels before the addition of blood and reagents results in a two-phase flow. The evaluation of this two-phase flow is necessary, and dynamic simulations are required to determine the PT. The chemical rate constant and order of the chemical reaction are derived from the actual prothrombin time. Moreover, the genetic algorithms in PYTHON and ANSYS are used to estimate chemical reaction parameters for a 20 s PT. The blood and anticoagulant exhibit increased dynamic behavior in the microchannel. In addition, particles are added to the microchannel and the dynamic mesh method is used to simulate the flow behaviors of the red and white blood cells in the microchannel. The PTs for different volumes of blood are also reported.
      Citation: Coatings
      PubDate: 2021-11-15
      DOI: 10.3390/coatings11111394
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1395: Influence of Carbon Nanowalls Interlayer on
           Copper Deposition

    • Authors: Cristiana-Alexandra Danes, Cristina Dumitriu, Sorin Vizireanu, Bogdan Bita, Ioana-Maria Nicola, Gheorghe Dinescu, Cristian Pirvu
      First page: 1395
      Abstract: This research deals with the deposition of copper on a steel substrate. Two different methods were investigated: electrochemical and magnetron sputtering. The deposition parameters were optimized to obtain a coating layer with uniform granular structure and good adhesion to the substrate. As a novelty, carbon nanowalls (CNW) were used as reinforcement in copper coatings on the steel surface. The morphology of the coatings, adhesion and Vickers microhardness were performed to emphasize the CNW influence on the coating properties. Open circuit potential and Tafel analysis were used for electrochemical characterization. These kinds of CNW-copper composite with improved hardness and adhesion and surface electrical resistance around 1 Ω·cm could have miscellaneous applications in different domains such as aerospace, electronics, automotive and power-generation.
      Citation: Coatings
      PubDate: 2021-11-16
      DOI: 10.3390/coatings11111395
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1396: Effects of Additives Containing
           Cyanopyridine on Electrodeposition of Bright Al Coatings from AlCl3-EMIC
           Ionic Liquids

    • Authors: Min Zhang, Dong Peng, Feifei Peng, Anwei Huang, Kaiqiang Song, Qingbing He, Changqing Yin, Jinsong Rao, Yuxin Zhang, Haitao Chen, Dalong Cong, Zhongsheng Li
      First page: 1396
      Abstract: The Al coatings were electrodeposited on the Cu substrate from AlCl3-EMIC ionic liquid (AlCl3:EMIC = 2:1 molar ratio) containing three cyanopyridine additives with different positions of the substituent group on the pyridine ring, which were 2-cyanopyridine, 3-cyanopyridine, and 4-cyanopyridine. The effects of cyanopyridine additives on the deposition potential, morphology, brightness, and corrosion properties of Al coatings were investigated. It was considered that the deposition potential of Al shifted to more negative overpotentials, the quality of Al coatings was promoted, and the corrosion property was improved by the cyanopyridine additives to a varying degree. Especially in the presence of 4-cyanopyridine, the flattest mirror bright Al coating was obtained, which had the smallest homogeneous nanocrystal grain size and strongest Al (200) crystallographic orientation. The average roughness Ra value was as low as 31 nm compared to that in the absence of cyanopyridine additives, which was 417 nm. Furthermore, the corrosion current density of the bright Al coating was three orders of magnitude lower than the rough Al coating, which resulted from the dense nanocrystal structure.
      Citation: Coatings
      PubDate: 2021-11-17
      DOI: 10.3390/coatings11111396
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1397: Green Synthesis of Carbon-Encapsulated
           Magnetic Fe3O4 Nanoparticles Using Hydrothermal Carbonization from Rattan
           Holocelluloses

    • Authors: Linxin Dai, Zhi Jin, Xinge Liu, Long Feng, Jianfeng Ma, Zhe Ling
      First page: 1397
      Abstract: How to design a simple and scalable procedure for manufacturing multifunctional carbon-based nanoparticles using lignocellulosic biomass directly is a challenging task. Based on the green chemistry concept, we developed a novel one-pot solution-phase reaction to prepare carbon-encapsulated magnetic nano-Fe3O4 particles (Fe3O4@C) with a tunable structure and composition through the hydrothermal carbonization (HTC) of Fe2+/Fe3+ loaded rattan holocelluloses pretreated with ionic liquids (EmimAc and AmimCl). The detailed characterization results indicated that the Fe3O4@C synthesized from the holocelluloses pretreated with ionic liquids (ILs) under alkaline conditions tends to have a higher saturation magnetization, probably due to the increased iron ions loading. Moreover, increasing the HTC temperature led to an increased abundance of hydroxyl groups on the surface of the synthesized particles and an elevated saturation magnetization. When EmimAc-treated holocelluloses were used as the carbon precursors, well-encapsulated Fe3O4@C nanoparticles were obtained with a maximum saturation magnetization of 42.6 emu/g. This synthetic strategy, coupled with the structure of the iron carbide-based composite and the proposed mechanism, may open a new avenue for the development of carbon-encapsulated iron oxide-based magnetic nanoparticles.
      Citation: Coatings
      PubDate: 2021-11-17
      DOI: 10.3390/coatings11111397
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1398: Homogeneity Assessment of Asphalt Concrete
           Base in Terms of a Three-Dimensional Air-Launched Ground Penetrating Radar
           

    • Authors: Xiaomeng Zhang, Wenyang Han, Luchuan Chen, Zhengchao Zhang, Zhichao Xue, Jincheng Wei, Xiangpeng Yan, Guiling Hu
      First page: 1398
      Abstract: Obtaining the required homogeneity, including uniform thickness and density, is very crucial for controlling the quality of flexible asphalt layers. Although non-destructive testing (NDT) methods are time-saving and less labor-intensive, they only provide indirect measurement data under testing area conditions and strongly depend on the explanations by prediction models. In this study, in terms of the three-dimensional air-launched Ground Penetrating Radar (GPR) technique, the dielectric constant of asphalt concrete base with dry conditions in pavements was detected and calculated by different methods (the Coring Method, Reflection Amplitudes Method and Common Mid-Point Method). According to the calculated dielectric constant, the thickness and density of asphalt concrete base were further calculated and assessed. Comparing with the Coring Method, the Common Mid-Point Method was recommended to calculate dielectric constants in order to obtain reliable thickness of asphalt pavement base. Among the Birefringence, Boettcher, Linearity indicator, and Rayleigh models, the Rayleigh model was suggested to predict the density, and the predicted density exhibited a good correlation coefficient with the measured one. Furthermore, by choosing these proper calculation methods, an assessment was successfully conducted to evaluate homogeneity of a constructed field pavement in practice.
      Citation: Coatings
      PubDate: 2021-11-17
      DOI: 10.3390/coatings11111398
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1399: A Study on the Corrosion Resistance of
           Hydrophobic Coatings on 65Mn Steel

    • Authors: Yufen Zhang, Qingcheng Du, Tiegui Lin, Shawei Tang, Jin Hu
      First page: 1399
      Abstract: Calcium stearate hydrophobic coatings with a hierarchical micro/nanostructure were prepared on 65Mn steel using direct current electrodeposition. The deposition time has a visible influence on the morphology, surface wettability and thickness of the coatings, but little effect on the phase composition. The corrosion behavior of the coated samples in 3.5 wt.% NaCl solution was also investigated. The prepared coatings at different deposition times show different corrosion resistance. The coating fabricated at 30 min has the best corrosion resistance due to the highest water contact angle and thicker coating.
      Citation: Coatings
      PubDate: 2021-11-18
      DOI: 10.3390/coatings11111399
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1400: An Atomization Model of Air Spraying Using
           the Volume-of-Fluid Method and Large Eddy Simulation

    • Authors: Yan Chen, Shiming Chen, Wenzhuo Chen, Jun Hu, Junze Jiang
      First page: 1400
      Abstract: When painting complex surfaces, such as large-curvature surfaces, poor coating quality is often obtained, which may be caused by lack of an appropriate atomization model, insufficient understanding of atomization mechanisms and laws, and improper painting parameters. This paper presents a numerical model of paint atomization of air spraying using the volume-of-fluid method and large eddy simulation. The interface capture and the turbulent flow were mainly considered in the model: the former was tracked by the volume-of-fluid method and the latter was predicted by the large eddy simulation. After the computational domain being meshed by the staggered-grid method, the governing equations were discretized by the finite volume method and were solved by the SIMPLE (Semi-Implicit Method for Pressure-Linked Equations) Consistent algorithm. The results of numerical simulations show that the characteristics of atomization flow field, such as velocity variation, pressure distribution, and paint volume fraction are in agreement with the regularities of atomization. Moreover, the primary and secondary atomization phenomena can be clearly observed: as soon as the paint issues from the nozzle, the paint flow begins to distort and the paint fragments continuously eject from the main paint flow and then these paint fragments distort and disintegrate into smaller elements. A comparison with the experimental data from the literature proves that the model of the whole atomization process of air spray is effective. The model is suitable for simulating the whole atomization process and easy to obtain initial conditions, which can be applied to set the appropriate painting parameters and study paint atomization mechanisms and laws in depth.
      Citation: Coatings
      PubDate: 2021-11-18
      DOI: 10.3390/coatings11111400
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1401: Antibacterial and Anti-Inflammatory Coating
           Materials for Orthopedic Implants: A Review

    • Authors: Gang Tan, Jing Xu, Walter Munesu Chirume, Jieyu Zhang, Hui Zhang, Xuefeng Hu
      First page: 1401
      Abstract: Orthopedic implant failure is the most common complication of orthopedic surgery, causing serious trauma and resulting in a tremendous economic burden for patients. There are many reasons for implant failure, among which peri-implant infection (or implant-related infection) and aseptic loosening are the most important. At present, orthopedic doctors have many methods to treat these complications, such as revision surgery, which have shown good results. However, if peri-implant infection can be prevented, this will bring about significant social benefits. Many studies have focused on adding antibacterial substances to the implant coating, and with a deeper understanding of the mechanism of implant failure, adding such substances by different modification methods has become a research hot spot. This review aims to summarize the antibacterial and anti-inflammatory substances that can be used as coating materials in orthopedic implants and to provide a reference for the prevention and treatment of implant failure caused by implant-related infection and excessive inflammation.
      Citation: Coatings
      PubDate: 2021-11-18
      DOI: 10.3390/coatings11111401
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1402: Prediction for Dilution Rate of AlCoCrFeNi
           Coatings by Laser Cladding Based on a BP Neural Network

    • Authors: Yutao Li, Kaiming Wang, Hanguang Fu, Xiaohui Zhi, Xingye Guo, Jian Lin
      First page: 1402
      Abstract: The dilution rate has a significant impact on the composition and microstructure of the coatings, and the dilution rate and process parameters have a complex coupling relationship. In this study, three process parameters, namely laser power, powder feeding rate, and scanning speed, were selected as variables to design the orthogonal experiment. The dilution rate and hardness data were obtained from AlCoCrFeNi coatings based on orthogonal experiments. Then, a BP neural network was used to establish a prediction model of the process parameters on the dilution rate. The established BP neural network exhibited good prediction of the dilution rate of AlCoCrFeNi coatings, and the average relative error between the predicted value and the experimental value was only 5.89%. Subsequently, the AlCoCrFeNi coating was fabricated with the optimal process parameters. The results show that the coating was well-formed without defects, such as cracks and pores. The microhardness of the AlCoCrFeNi coating prepared with the optimal process parameters was 521.6 HV0.3. The elements were uniformly distributed in the microstructure, and the grain size was about 20–60 μm. The microstructure of the AlCoCrFeNi coating was only composed of the BCC phase without the existence of the FCC phase and intermetallic compounds.
      Citation: Coatings
      PubDate: 2021-11-18
      DOI: 10.3390/coatings11111402
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1403: Development of Microstructured Carbon
           Coatings by Substrate-Catalytic CVD

    • Authors: Mattia Pierpaoli, Mirosław Sawczak, Anna Dettlaff
      First page: 1403
      Abstract: Carbon nanostructured films were synthesized by chemical vapor deposition (CVD) on H18 stainless steel (AISI 440C) sheets with an H2/CH4/N2 gas mixture at various substrate temperatures. During the synthesis, the iron and chromium oxide layer was formed between the steel and carbonaceous layer. The carbon films exhibited wall-like and spherical morphologies and structures, as characterized by scanning electron microscopy and Raman spectroscopy. It was found that the synthesis temperature affects the microsphere density and, therefore, also in the electrochemical behavior. The electrochemical behavior of nanostructured carbon coatings strongly depends on the CVD deposition conditions. The best corrosion resistance (Rp = 11.8 MΩ·cm2, Icorr = 4.4 nA·cm−2) exhibits a nanostructured carbon sample with a moderate amount of sp2-C-rich carbon microspheres CμSs synthesized at 700 °C. The corrosion resistance of the nanostructured carbon coating is better than raw stainless steel.
      Citation: Coatings
      PubDate: 2021-11-18
      DOI: 10.3390/coatings11111403
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1404: Experimental Study on Axial Compressive
           Behavior of Gangue Aggregate Concrete Filled FRP and Thin-Walled Steel
           Double Tubular Columns

    • Authors: Jian Wang, Junwu Xia, Hongfei Chang, Youmin Han, Linli Yu, Li Jiang
      First page: 1404
      Abstract: In the present paper, the monotonic axial compression test of gangue aggregate concrete filled Fiber reinforced polymer (FRP) and thin-walled steel double tubular columns (DTCC) was carried out, and the gangue aggregate concrete filled FRP tubular columns (CFFT) were designed as a comparison. The main experimental factors were the confinement level of the FRP jacket, the relative diameter ratio (the ratio of the outer diameter of the steel tube to the inner diameter of the FRP jacket), and the different strengths of gangue aggregate concrete. The test results show that the bearing capacity and ductility of gangue aggregate concrete in CFFT were significantly improved. As the local buckling of thin-walled steel tube was effectively inhibited, the load bearing capacity of DTCC was further improved compared with CFFT, but the change of dilation behavior and ductility was insignificant. By analyzing the bi-directional stress state of the steel tube, the confinement level of the external FRP jacket was the most sensitive factor affecting the hoop stress of the steel tube, and the axial stress was obviously weakened under the bi-directional stress state. In addition, with the increase of steel tube diameter, the confinement effect of steel tube in DTCC became more obvious.
      Citation: Coatings
      PubDate: 2021-11-18
      DOI: 10.3390/coatings11111404
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1405: Simulation of Cold Atmospheric Plasma
           Generated by Floating-Electrode Dielectric Barrier Pulsed Discharge Used
           for the Cancer Cell Necrosis

    • Authors: Samira Elaissi, Kamel Charrada
      First page: 1405
      Abstract: A numerical simulation of a pulsed floating electrode dielectric barrier discharge (FE-DBD) at atmospheric pressure, used for melanoma cancer cell therapy, is performed using a plasma model in COMSOL Multiphysics software. Distributions of electron density, space charge, and electric field are presented at different instants of the pulsed argon discharge. Significant results related to the characteristics of the plasma device used, the inter-electrodes distance, and the power supply are obtained to improve the efficiency of FE-DBD apparatus for melanoma cancer cell treatment. The FE-DBD presents a higher sensitivity to short pulse durations, related to the accumulated charge over the dielectric barrier around the powered electrode. At higher applied voltage, more energy is injected into the discharge channel and an increase in electron density and electric consumed power is noted. Anticancer activity provided by the FE-DBD plasma is improved using a small interelectrode distance with a high electron emission coefficient and a high dielectric constant with a small dielectric thickness, allowing higher electron density, generating reactive species responsible for the apoptosis of tumor cells.
      Citation: Coatings
      PubDate: 2021-11-19
      DOI: 10.3390/coatings11111405
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1406: The Effect of Gaseous Ozone and Moringa
           Leaf–Carboxymethyl Cellulose Edible Coating on Antioxidant Activity and
           Biochemical Properties of ‘Keitt’ Mango Fruit

    • Authors: Nonjabulo L. Bambalele, Asanda Mditshwa, Lembe Samukelo Magwaza, Samson Zeray Tesfay
      First page: 1406
      Abstract: This study evaluated the effect of edible coating and gaseous ozone on the antioxidant activities and biochemical properties of mango fruit. Mango fruit (cv. Keitt) were coated with moringa leaf extract and carboxymethyl cellulose (EC) before exposure to ozone (0.25 ppm). Gaseous ozone (O3) was administered intermittently for 24 or 36 h, and the control fruit were untreated. The fruit were stored at 10 °C for twenty-one days, then ripened at ambient temperature for seven days. The parameters measured were ascorbic acid, lipid peroxidation, phenolic content, total sugars, and antioxidant capacity (FRAP and DPPH). At the end of storage, the EC + O3 (36 h) had high phenolic content: 175.02 µg GEA/g DM compared to 151.87 µg GEA/g DM and 138.98 µg GEA/g DM for the O3 (24 h) and untreated fruit, respectively. Moreover, the combination of the EC and O3 (36 h) had a higher effect (p < 0.05) on preserving the antioxidant capacity of the mangoes. The EC + O3 (24 h) and EC significantly delayed fruit softening and maintained membrane integrity. Furthermore, the fruit treated with the EC reduced the accumulation of reducing (7.61 mg/mL) and total sugars (8.81 mg/mL) compared to the control treatment, which had a concentration of 12.74 mg/mL and 13.78 mg/mL, respectively. These findings demonstrate that EC combined with gaseous O3 enhanced the antioxidants of mango fruit during storage.
      Citation: Coatings
      PubDate: 2021-11-19
      DOI: 10.3390/coatings11111406
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1407: Arsenic Removal from Contaminated Water
           Using Natural Adsorbents: A Review

    • Authors: Kanfolo Franck Herve YEO, Chaokun Li, Hui Zhang, Jin Chen, Wendong Wang, Yingying Dong
      First page: 1407
      Abstract: More than 170 million individuals have been influenced by arsenic (As) because of the ingestion of As-polluted groundwater. The presence of As in water bodies, particularly groundwater, has been found to become a widespread issue in the past few decades. Because arsenic causes extreme wellbeing impacts, even at a low concentration in drinking water, the innovations of As removal from contaminated water are of significant importance. Traditional strategies, for example, reverse osmosis, ion exchange, and electro-dialysis are generally utilized for the remediation of As-polluted water; however, the high cost and/or sludge production restricts their application in less-developed areas. The utilization of adsorbents acquired from natural materials has been explored as an alternative for the costly techniques for As removal. This paper aims to review the past and current developments in using naturals adsorbents or modified natural materials for arsenic removal and show the different parameters, which may influence the As removal effectiveness of the natural adsorbent, such as contact time, adsorbent dosage, flow rate, pH, reusability, temperature, and influence of others ions.
      Citation: Coatings
      PubDate: 2021-11-19
      DOI: 10.3390/coatings11111407
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1408: Spheroidization Behavior of Nano-Primary
           Silicon Induced by Neodymium under High-Current Pulsed Electron Beam
           Irradiation

    • Authors: Liang Hu, Kui Li, Bo Gao, Ning Xu, Zhuang Liu, Yue Sun, Ying Zhang, Pengfei Xing
      First page: 1408
      Abstract: The spheroidization behavior of the nano-primary silicon phase induced by Nd under high-current pulsed electron beam (HCPEB) irradiation was investigated in this study. The study results revealed that, compared to the Al–17.5Si alloy, spheroidized nano-primary silicon phase emerged in the alloy’s HCPEB-irradiated surface layer due to the presence of Nd. Because Nd was abundantly enriched on the fast-growing silicon crystal plane, its surface tension was reduced under the extreme undercooling caused by HCPEB irradiation, causing the growth velocity of each crystal plane to be the same and spherical nanometers of silicon to appear. The spheroidization of nano-primary silicon phases occurred in the remelted layer. The microhardness test revealed that Nd could depress the microhardness of the Al matrix at the same number of pulses, but conversely increase the microhardness of the primary silicon phase, compared to the Al–17.5Si alloy. The tribological test showed that the presence of spherical nano-primary silicon could significantly improve the alloy’s tribological property.
      Citation: Coatings
      PubDate: 2021-11-19
      DOI: 10.3390/coatings11111408
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1409: Validation of Antibacterial Systems for
           Sustainable Ceramic Tiles

    • Authors: Valeria La Torre, Elisa Rambaldi, Giulia Masi, Silvia Nici, Daniele Ghezzi, Martina Cappelletti, Maria Chiara Bignozzi
      First page: 1409
      Abstract: Ceramic tiles are bacteriostatic materials; however, the COVID-19 emergency has pushed tile producers to improve surfaces’ antibacterial properties. The aim of this work was to validate a silver-based antibacterial treatment applied to porcelain stoneware tiles based on natural and waste materials, thus correlating surface functionalization to tile composition and relevant physical, microstructural, and textural parameters. The treatment was applied before firing, with and without a polymeric primer. Antibacterial activity tests, stain resistance tests, and contact angle measurements were carried out on fired tiles. Further investigations were made by SEM and optical profilometry in order to study the morphological–structural profile of tile surfaces. Results showed strong antibacterial activities for all the functionalized tiles, which were mainly correlated to the morphological and textural parameters of ceramic surfaces, as well as the presence of the polymeric primer.
      Citation: Coatings
      PubDate: 2021-11-19
      DOI: 10.3390/coatings11111409
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1410: Physicochemical Investigation of
           Biosynthesis of a Protein Coating on Glass That Promotes Mammalian Cell
           Growth Using Lactobacillus rhamnosus GG Bacteria

    • Authors: Kamil Kaminski, Karolina Syrek, Joanna Grudzień, Magdalena Obloza, Monika Adamczyk, Grzegorz D. Sulka
      First page: 1410
      Abstract: Glass surfaces, although the first to be used for culturing ex vivo adherent cells, are not the perfect substrates for this purpose. Today, plastics dominate these applications, but in light of the global trend to reduce the use of synthetic polymers, it is reasonable to consider a return to glass vessels with coatings for these purposes. The ideal surface for cell growth is one that simulates the composition and structure of the mainly protein-based intercellular matrix. The work presented here shows a new idea of preparing porous protein coatings on glass using biosynthesis. The process utilizes the colonization of the gold nanoparticle-coated glass surface with Lactobacillus rhamnosus GG bacteria, followed by permeabilization (using ethanol) of their membrane and partial thermal degradation (at 160 °C in vacuum) of the surface-bound protein components of these microorganisms. It results in a development of coating on the glass that promotes mammalian cell growth, which has been preliminary confirmed using Vero cells. Subsequent steps in the formation of coating components were documented by reflectance ultraviolet and visible spectra and infrared spectroscopy. The presence of microorganisms and mammalian cells was confirmed using scanning electron and optical microscopy and crystalline violet staining.
      Citation: Coatings
      PubDate: 2021-11-19
      DOI: 10.3390/coatings11111410
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1411: Large Negative Photoresistivity in
           Amorphous NdNiO3 Film

    • Authors: Alexandr Stupakov, Tomas Kocourek, Natalia Nepomniashchaia, Marina Tyunina, Alexandr Dejneka
      First page: 1411
      Abstract: A significant decrease in resistivity by 55% under blue lighting with ~0.4 J·mm−2 energy density is demonstrated in amorphous film of metal-insulator NdNiO3 at room temperature. This large negative photoresistivity contrasts with a small positive photoresistivity of 8% in epitaxial NdNiO3 film under the same illumination conditions. The magnitude of the photoresistivity rises with the increasing power density or decreasing wavelength of light. By combining the analysis of the observed photoresistive effect with optical absorption and the resistivity of the films as a function of temperature, it is shown that photo-stimulated heating determines the photoresistivity in both types of films. Because amorphous films can be easily grown on a wide range of substrates, the demonstrated large photo(thermo)resistivity in such films is attractive for potential applications, e.g., thermal photodetectors and thermistors.
      Citation: Coatings
      PubDate: 2021-11-19
      DOI: 10.3390/coatings11111411
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1412: Influence of Different Acid on the
           Interfacial Compatibility between Rusted Steel and Water-Based Coating

    • Authors: Wenbo Li, Yue Jiang, Dingguo Liu, Jiran Zhu, Yi Xie, Lanlan Liu
      First page: 1412
      Abstract: We aimed to improve the corrosion resistance of transmission network cabinet equipment in high temperature and humidity environment. In this paper, using acid modified acrylic acid as the main component, the composite conversion agent was obtained by adding phosphoric acid phytic acid and other components. Through the surface morphology, electrochemical test and adhesion force test of rust conversion coating, the versatility and corrosion resistance of rust conversion coating on the substrates were analyzed. Combined with zinc phosphate primer, the effect of rust conversion agent on the adhesion and salt spray corrosion resistance of the commercial primers was studied. The composite conversion agent has good effect on atmospheric corrosion rust layer. The corrosion resistance and adhesion force of the atmospheric corrosion rust layer treated with rust conversion agent were significantly increased. The adhesion of zinc phosphate primer on atmospheric corrosion rust coating with rust conversion was three times higher than that of atmospheric corrosion rust coating without rust conversion, respectively. Composite rust conversion agent has broad versatility, which can be used for rust conversion of atmospheric corrosion rust layer. At the same time, it has a good corrosion resistance, that can obviously improve the corrosion potential of the corroded surface and reduce the corrosion current density. In addition, the composite rust conversion agent can significantly improve the adhesion and corrosion resistance of the primer coating.
      Citation: Coatings
      PubDate: 2021-11-19
      DOI: 10.3390/coatings11111412
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1413: Development of Antimicrobial Cotton Fabric
           Impregnating AgNPs Utilizing Contemporary Practice

    • Authors: Md. Reazuddin Repon, Tarikul Islam, Halima Tus Sadia, Daiva Mikučionienė, Shakhawat Hossain, Golam Kibria, Mosab Kaseem
      First page: 1413
      Abstract: Multifunctional fabrics using conventional processes have piqued increasing global interest. The focus of this experiment was to assess the modification of the cotton fabric surface by utilizing silver nanoparticles (AgNPs) and introducing functional properties along with sustainable dyeing performance. A single-jersey knitted fabric composed of cellulose-enriched 100% natural fiber (cotton) with an areal density of 172 GSM was used in this study. The standard recipe and test methods were employed. FTIR-ATR spectra were used to determine the fixing of AgNPs onto the fiber surface. A comparative assessment was conducted in response to the distribution of color, color fastness to wash, water, perspiration, rubbing, and light. Scanning electron microscopy (SEM) was used to characterize the surface of nano-Ag-deposited specimens. In terms of functional properties, antimicrobial activity was scrutinized. Our findings reveal that the nanoparticles impart remarkable antibacterial effects to cellulose-enriched fabric against S. aureus (Gram-positive) and E. coli (Gram-negative). Direct dyes were used for dyeing the proposed samples, resulting in enhanced dyeing performance. Except for light fastness, the samples dipped with AgNPs showed outstanding color levelness and color durability characteristics. The developed fabrics can be applied in a wide range of functions, including protective clothing, packaging materials, and healthcare, among others.
      Citation: Coatings
      PubDate: 2021-11-19
      DOI: 10.3390/coatings11111413
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1414: Electroplating of Pure Aluminum from
           [HMIm][TFSI]–AlCl3 Room-Temperature Ionic Liquid

    • Authors: Yarden Melamed, Nabasmita Maity, Louisa Meshi, Noam Eliaz
      First page: 1414
      Abstract: Electrodeposition of aluminum and its alloys is of great interest in the aerospace, automobile, microelectronics, energy, recycle, and other industrial sectors, as well as for defense and, potentially, electrochemical printing applications. Here, for the first time, we report room-temperature electroplating of pure aluminum on copper and nickel substrates from an ionic liquid (IL) consisting of 1-Hexyl-3-methylimidazolium (HMIm) cation and bis(trifluoromethylsulfonyl)imide (TFSI) anion, with a high concentration of 8 mol/L AlCl3 aluminum precursor. The aluminum deposits are shown to have a homogeneous and dense nanocrystalline structure. A quasi-reversible reaction is monitored, where the current is affected by both charge transfer and mass transport. The electrocrystallization of Al on Ni is characterized by instantaneous nucleation. The deposited Al layers are dense, homogeneous, and of good surface coverage. They have a nanocrystalline, single-phase Al (FCC) structure, with a dislocation density typical of Al metal. An increase in the applied cathodic potential from −1.3 to −1.5 V vs. Pt resulted in more than one order of magnitude increase in the deposition rate (to ca. 44 μm per hour), as well as in ca. one order of magnitude finer grain size. The deposition rate is in accordance with typical industrial coating systems.
      Citation: Coatings
      PubDate: 2021-11-19
      DOI: 10.3390/coatings11111414
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1415: Formation of Solid Lubricants during High
           Temperature Tribology of Silver-Doped Molybdenum Nitride Coatings
           Deposited by dcMS and HIPIMS

    • Authors: Martin Fenker, Martin Balzer, Sabine Kellner, Tomas Polcar, Andreas Richter, Frank Schmidl, Tomas Vitu
      First page: 1415
      Abstract: The coating system MoN-Ag is an interesting candidate for industrial applications as a low friction coating at elevated temperatures, due to the formation of lubricous molybdenum oxides and silver molybdates. Film deposition was performed by high-power impulse magnetron sputtering and direct current magnetron sputtering. To facilitate a future transfer to industry Mo-Ag composite targets have been sputtered in Ar/N2 atmosphere. The chemical composition of the deposited MoN-Ag films has been investigated by wavelength dispersive X-ray spectroscopy. Morphology and crystallographic phases of the films were studied by scanning electron microscopy and X-ray diffraction. To obtain film hardness in relation to Ag content and bias voltage, the instrumented indentation test was applied. Pin-on-disc tribological tests have been performed at room temperature and at high temperature (HT, 450 °C). Samples from HT tests have been analyzed by Raman measurements to identify possible molybdenum oxide and/or silver molybdate phases. At low Ag contents (≤7 at.%), coatings with a hardness of 18–31 GPa could be deposited. Friction coefficients at HT decreased with increasing Ag content. After these tests, Raman measurements revealed the MoO3 phase on all samples and the Ag2Mo4O13 phase for the highest Ag contents (~23–26 at.%).
      Citation: Coatings
      PubDate: 2021-11-19
      DOI: 10.3390/coatings11111415
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1416: A Novel Technique for Controllable
           Fabrication of Multilayer Copper/Brass Block

    • Authors: Jiansheng Li, Zhongchen Zhou, Tong Liu, Yu Zhao, Yan Lu, Ming Chen, Xiaozhen Wang, Gang Wang, Qingzhong Mao
      First page: 1416
      Abstract: Fabricating a dissimilar-metal block with micro/nano-multilayered structures is usually used by engineers and scientists because of their excellent mechanical properties. In the current work, multilayered copper/brass blocks were effectively fabricated by a synthetical DWFR technique, which includes the processes of diffusion welding, forging and rolling. Diffusion welding was used as the first operation to metallurgically bond the copper and brass sheets, with a Zn diffusion transition layer (thickness of ~100 μm), which can guarantee the bonding strength of copper/brass interfaces during the subsequent forging and rolling processes. After diffusion welding, the original copper/brass blocks were required to be forged, with its total thickness reduced to ~10 mm. This can further restrain the delamination of copper and brass layers during the final rolling process. Rolling was utilized as the ideal operation that can precisely tune the thickness of copper/brass laminate. This novel DWFR technique can easily tune the multilayered copper/brass blocks with controllable layer thickness (from ~250 to ~800 nm). The copper/brass interfaces were well-bonded, and the utilization efficiency of raw materials was very high (>95%).
      Citation: Coatings
      PubDate: 2021-11-20
      DOI: 10.3390/coatings11111416
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1417: Corrosion Behavior of Chromium Coated Zy-4
           Cladding under CANDU Primary Circuit Conditions

    • Authors: Diana Diniasi, Florentina Golgovici, Alexandru Anghel, Manuela Fulger, Carmen Cristina Surdu-Bob, Ioana Demetrescu
      First page: 1417
      Abstract: The manuscript is focused on corrosion behavior of a Cr coating under CANada Deuterium Uranium(CANDU) primary circuit conditions. The Cr coating is obtained via the thermionic vacuum arc procedure on Zircaloy -4 cladding. The surface coating characterization was performed using metallographic analysis and scanning electron microscopy (SEM) with an energy dispersive spectra detector (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) investigations. The thickness of the Cr coating determined from SEM images is around 500 nm layers After the autoclaving period, the thickness of the samples increased in time slowly. The kinetic of oxidation established a logarithmic oxidation law. The corrosion tests for various autoclaving periods of time include electrochemical impedance spectroscopy (EIS) and potentiodynamic tests, permitting computing porosity and efficiency of protection. All surface investigations sustain electrochemical results and promote the Cr coating on Zircaloy-4 alloy autoclaved for 3024 h as the best corrosion resistance based on decrease in corrosion current density values simultaneously with the increase of the time spent in autoclave. A slow increase of Vickers micro hardness was observed as a function of the autoclaved period as well. The value reached for 3024 h being 219 Kgf/mm2 compared with 210 Kgf/mm2 value before autoclaving.
      Citation: Coatings
      PubDate: 2021-11-20
      DOI: 10.3390/coatings11111417
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1418: Obliquely Bideposited TiN Thin Film with
           Morphology-Dependent Optical Properties

    • Authors: Yi-Jun Jen, Wei-Chieh Ma, Ting-Yen Lin
      First page: 1418
      Abstract: TiN thin films were obliquely bideposited with different subdeposit thicknesses. The morphology of the bideposited film was varied from a nano-zigzag array to a vertically grown columnar structure by reducing the subdeposit thickness. The principal index of refraction and extinction coefficient were obtained to explain the measured reflectance and transmittance spectra. The loss of the bideposited thin film decreased as the thickness of the subdeposit decreased. The principal indices for normal incidence were near or under unity, indicating the low reflection by the bideposited thin films. A TiN film with a subdeposit thickness of 3 nm demonstrated an average index of refraction of 0.83 and extinction coefficient of below 0.2 for visible wavelengths. The retrieved principal refractive indexes explained the anisotropic transmission and reflection. For most normal incident cases, the analysis offers the tunable anisotropic property of a TiN nanostructured film for multilayer design in the future.
      Citation: Coatings
      PubDate: 2021-11-20
      DOI: 10.3390/coatings11111418
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1419: Degradation Mechanisms Occurring in
           PTFE-Based Coatings Employed in Food-Processing Applications

    • Authors: Alfredo Rondinella, Francesco Andreatta, Daniele Turrin, Lorenzo Fedrizzi
      First page: 1419
      Abstract: The application of polytetrafluoroethylene (PTFE) coatings to metal surfaces is a well-known procedure carried out to avoid fouling phenomena on food-processing surfaces. Fluorine-based polymers are generally chemically and thermally stable, thus allowing them to be the preferred choice when designing anti-stick coatings in the food service industry. Their lifespan, however, depends on the environmental conditions. It is well known that thermal ageing can affect the properties of PTFE polymers and reduce their mechanical, thermal, and chemical properties causing failures and contaminating food. The main goal of the study is to identify the different failure mechanisms occurring in PTFE-based coatings, using both SEM/EDXS and ATR FT-IR data to reveal the starting point of degradation phenomena in food processing applications. The results from this research reveal that the preferential points for failures are mainly the polymer/substrate interfaces, the polymer/filler interfaces, or the polymer matrix itself.
      Citation: Coatings
      PubDate: 2021-11-20
      DOI: 10.3390/coatings11111419
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1420: Data Analysis of Two-Phase Flow Simulation
           Experiment of Array Optical Fiber and Array Resistance Probe

    • Authors: Shuaifei Cui, Junfeng Liu, Kui Li, Qinze Li
      First page: 1420
      Abstract: To solve the problem that traditional single-probe instruments cannot accurately measure the gas and water holdup, the domestic design of the array holdup measuring instrument Array of Optical and Resistance Tool (AORT), composed of five sets of optical fiber probes and five sets of resistance probes, is carried out in both gas–water and oil–water. Simulated measurement experiments were conducted under different water cut in phase flow. Through the analysis of the experimental data, the response relationship between the optical fiber probe and the resistance probe of the AORT instrument in different fluids was obtained. Then, the data under different conditions of fluid, flowrate and water cut in the experiment were compared by drawing. Interpolation algorithm was used to perform two-maintenance holdup imaging, and finally the holdup image was compared with the pictures of the flow in the pipe recorded during the experiment. The results show that the resistance probe has a better response under low water cut conditions, and the optical fiber probe has a better response under high gas cut conditions, which is consistent with the theoretical analysis. The imaging diagram and the flow pattern in the pipe during the experiment are in good agreement. It can be seen that the accuracy of the holdup measured by the AORT instrument under the test conditions is verified, and can provide technical support for further carrying out the measurement and interpretation of the holdup in future, as well as the improvement of the instrument and on-site testing.
      Citation: Coatings
      PubDate: 2021-11-20
      DOI: 10.3390/coatings11111420
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1421: Non-Destructive Evaluation of Coating
           Thickness Using Water Immersion Ultrasonic Testing

    • Authors: Jiannan Zhang, Younho Cho, Jeongnam Kim, Azamatjon Kakhramon ugli Malikov, Young H. Kim, Jin-Hak Yi, Weibin Li
      First page: 1421
      Abstract: The coating is applied to prevent corrosion on the surface of ships or marine structures, and the thickness of the coating affects its anti-corrosion effect. As a result, non-destructive testing (NDT) is required to measure coating thickness, and ultrasonic NDT is a convenient and quick way to measure the thickness of underwater coatings. However, the offshore coating’s energy attenuation and absorption rates are high, the ultrasonic pulse echo test is difficult, and the testing environment is harsh. Because of the coating’s high attenuation, the distance of the optimal water delay line designed based on the reflection coefficient of the vertically incident wave is used. To accurately measure the thickness of the coating material, TOF of the reflected echo on the time-domain waveform was evaluated. The experimental results show that, when compared to caliper measurements, the coating thickness measured by the proposed method has a lower error and can be used for accurate measurement. The use of ultrasonic water immersion measurement is almost limitless in terms of size, location, and material of the object to be measured, and it is expected to be used to measure the thickness of the surface coating of ships or marine structures in the water.
      Citation: Coatings
      PubDate: 2021-11-20
      DOI: 10.3390/coatings11111421
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1422: Enhanced Anticorrosion Properties through
           Structured Particle Design of Waterborne Epoxy-Styrene-Acrylate Composite
           Emulsion

    • Authors: Kai Zhang, Xifang Chen, Yuling Xiao, Rujia Liu, Jie Liu
      First page: 1422
      Abstract: In order to develop a waterborne epoxy-styrene–acrylate composite latex with a better stability and anticorrosion resistance, a novel synthetic approach has been proposed. First, modified by methyl acrylic, epoxy resin containing terminal C=C double bonds was successfully synthesized, where epoxide groups were partially retained. Then, by structural design and multi-stage seed emulsion copolymerization, a stable waterborne epoxy-styrene-acrylate composite latex composed of a modified epoxy resin acrylate polymer as the core, inert polystyrene ester as the intermediate layer, and carboxyl acrylate polymer as the shell was successfully fabricated. The structure of the obtained latex was characterized by fourier transform infrared (FTIR) and transmission electron microscopy (TEM). The stability of the composite latex was tested based on the wet gel weight, Zeta potential, and storage stability, and the corrosion resistance of the composite latex films was analyzed by electrochemical measurements and salt spray tests. The thickness of each layer of the composite latex was calculated by the temperature random multi-frequency modulation DSC (TOPEM-DSC) technique. In addition to the successful emulsion copolymerization that occurred between the modified epoxy resin and acrylate monomer, the presence of carboxyl groups in the obtained latex was evidenced, while the epoxide groups were partially retained. The anticorrosion resistance and stability of the multilayer composite latex with the intermediate layer are better than that of the conventional core-shell latex. The outstanding stability and corrosion resistance is attributed to the multilayer core-shell structure. The TOPEM-DSC approach can accurately determine the thickness of the intermediate layer in the multilayer core-shell particles and is a new strategy for characterizing the core-shell structure of polymer particles with a similar monomer composition.
      Citation: Coatings
      PubDate: 2021-11-21
      DOI: 10.3390/coatings11111422
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1423: Overview of Bioplastic Introduction and Its
           Applications in Product Packaging

    • Authors: Nor Izaida Ibrahim, Farah Syazwani Shahar, Mohamed Thariq Hameed Sultan, Ain Umaira Md Shah, Syafiqah Nur Azrie Safri, Muhamad Hasfanizam Mat Yazik
      First page: 1423
      Abstract: Each year, more than 330 million tons of plastic are produced worldwide. The main consumers of plastics are the packaging (40%), building (20%) and automotive (8%) industries, as well as for the manufacture of household appliances. The vast majority of industrial plastics are not biodegradable and, therefore, create environmental problems due to the increase in the amount of solid waste. Studies have been conducted to produce biodegradable materials such as bioplastics to overcome this environmental problem. Bioplastics are defined as materials that are bio-based, biodegradable, or both; they can provide excellent biodegradability and can be used to help alleviate environmental problems. Therefore, this article presents an overview of the introduction of bioplastic materials and classifications, and a comprehensive review of their drawbacks and areas of importance, including basic and applied research, as well as biopolymer mixtures and biocomposites developed in the last decade. At the same time, this article provides insights into the development of bioplastics research to meet the needs of many industries, especially in the packaging industry in Malaysia. This review paper also focuses generally on bioplastic packaging applications such as food and beverage, healthcare, cosmetics, etc.
      Citation: Coatings
      PubDate: 2021-11-22
      DOI: 10.3390/coatings11111423
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1424: Sialon and Alumina Modified UV-Curable
           Coatings with Improved Mechanical Properties and Hydrophobicity

    • Authors: Mariola Robakowska, Łukasz Gierz, Hubert Gojzewski
      First page: 1424
      Abstract: This article describes the modification of UV-curable coatings with silicon aluminum oxynitride (Sialon) and aluminum oxide (Alu C), which improve the hydrophobicity of the coating surface and the scratch hardness. The contact angle is greater due to surface roughness being enhanced with inorganic fillers. Improved scratch resistance results from the formation of a sliding layer triggered by the diffusion of Sialon or alumina on the coating surface. One can observed an increase in the surface hydrophobicity as well as in the scratch hardness (up to 100%) when small amounts (5 wt.%) of the inorganic compounds are added. Imaging microscopies, i.e., SEM, OM, and AFM (with nanoscopic Young’s modulus determination), revealed the good distribution of both types of fillers in the studied matrix.
      Citation: Coatings
      PubDate: 2021-11-22
      DOI: 10.3390/coatings11111424
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1425: Corrosion and Biocompatibility of Pure Zn
           with a Micro-Arc-Oxidized Layer Coated with Calcium Phosphate

    • Authors: Yixuan Shi, Lijing Yang, Lucai Wang, Qingke Zhang, Xinglong Zhu, Wensheng Sun, Jianwei Shen, Ting Lu, Zhenlun Song, Huinan Liu
      First page: 1425
      Abstract: Recent studies have indicated a great demand to optimize the biocompatibility properties of pure Zn as an implant material. For this purpose, CaZn2(PO4)2·2H2O (CaZnP) was prepared using hydrothermal treatment (HT) combined with micro-arc oxidation (MAO) on pure Zn substrate to generate biodegradable implants. The polarization test and electrochemical impedance spectroscopy indicated that the MAO1−HT coating could modulate the corrosion behavior of MAO1 by filling the crevice between the coating and the substrate. Immersion test evaluation revealed that the osteogenic properties of MAO1−HT coating were better than that of pure Zn substrate, as evidenced by the molar ratio of Ca and P, which increased after soaking in simulated body fluid (SBF) for up to 10 days. In addition, L-929 cells cultured in the 100%, 50%, and 25% extracts of MAO1−HT coated samples exhibited excellent cytocompatibility. Meanwhile, cell adhesion was promoted on the surface with high roughness generated during MAO and HT processes. In summary, the calcified coatings improved biocompatibility and adjusted the degradation rates of pure Zn, broadening the application of Zn alloys.
      Citation: Coatings
      PubDate: 2021-11-22
      DOI: 10.3390/coatings11111425
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1426: Effect of the Acid-Etching on Grit-Blasted
           Dental Implants to Improve Osseointegration: Histomorphometric Analysis of
           the Bone-Implant Contact in the Rabbit Tibia Model

    • Authors: Blanca Ríos-Carrasco, Bernardo Ferreira Lemos, Mariano Herrero-Climent, F. Javier Gil Mur, Jose Vicente Ríos-Santos
      First page: 1426
      Abstract: Previous studies have shown that the most reliable way to evaluate the success of an implant is by bone-to-implant contact (BIC). Recent techniques allow modifications to the implant surface that improve mechanical and biological characteristics, and also upgrade osseointegration. Objective: The aim was to evaluate the osseointegration in rabbit tibia of two different titanium dental implant surfaces: shot-blasted with Al2O3 (SB) and the same treatment with an acid-etching by immersion for 15 s in HCl/H2SO4 (SB + AE). Material and methods: Roughness parameters (Ra, Rt, and Rz) were determined by white light interferometer microscopy. Surface wettability was evaluated with a contact angle video-based system using water, di-iodomethane, and formamide. Surface free energy was determined by means of Owens and Wendt equations. Scanning electron microscopy equipped with X-ray microanalysis was used to study the morphology and determine the chemical composition of the surfaces. Twenty-four grade 4 titanium dental implants (Essential Klockner®) were implanted in the rabbit’s tibia, 12 for each surface treatment, using six rabbits. Six weeks later the rabbits were sacrificed and the implants were sent for histologic analysis. Resonance frequency analysis (RFA) was recorded both at the time of surgery and the end of the research with each device (Osstell Mentor and Osstell ISQ). Results: The roughness measurements between the two treatments did not show statistically significant differences. However, the effect of the acid etching made the surface slightly more hydrophilic (decreasing contact angle from 74.7 for SB to 64.3 for SB + AE) and it presented a higher surface energy. The bone-to-implant contact ratio (BIC %) showed a similar tendency, with 55.18 ± 15.67 and 59.9 ± 13.15 for SB and SB + AE implants, respectively. After 6 weeks of healing, the SB + AE showed an implant stability quotient (ISQ) value of 76 ± 4.47 and the shot-blasted one an ISQ value of 75.83 ± 8.44 (no statistically significant difference). Implants with different surface properties had distinctive forms of behavior regarding osseointegration. Furthermore, the Osstell system was an invasive and reliable method to measure implant stability. Conclusion: Both surfaces of implants studied showed high osseointegration. The SB and SB + AE implants used in our study had similar behavior both in terms of BIC values and RFA. The RFA systems in Osstell Mentor and Osstell ISQ confirmed nearly perfect reproducibility and repeatability.
      Citation: Coatings
      PubDate: 2021-11-22
      DOI: 10.3390/coatings11111426
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1427: PLGA Coatings and PLGA Drug-Loading
           Coatings for Cardiac Stent Samples: Degradation Characteristics and Blood
           Compatibility

    • Authors: Ziyang Jia, Chunyang Ma, Hongbin Zhang
      First page: 1427
      Abstract: PLGA (Poly lactic-co-glycolic acid) and PLGA drug-loading coatings were prepared on 316 L stainless steel by electrostatic spray deposition (ESD). The surface morphology, three-dimensional morphology, and crystal structures of the coatings were observed by scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD). Thermal properties, molecular weight, and coating composition were studied by differential scanning calorimetry (DSC), gel permeation chromatography (GPC), and NMR. The degradation behaviors of the coatings were studied by mass changes, relative molecular mass and distributions, polymer compositions, thermal properties, and surface morphologies. The blood compatibilities of the coatings were investigated by platelet adhesion testing and dynamic coagulation times. SEM results indicated the drug-loading coating with 33% RAPA had the smoothest and most compact morphology. Addition of RAPA decreased the Tg of the PLGA coating, accompanied by partial crystallization that slowed the degradation rate of the drug-loaded coating. Microscopically, the morphology of the PLGA drug-loaded coating was coarser than the PLGA coating. The average surface roughness values of line and surface scannings were 16.232 nm and 39.538 nm, respectively. The surface of the drug-loading coating was micro uneven, and the macro smooth and micro multiphase separation structure helped improve its blood compatibility.
      Citation: Coatings
      PubDate: 2021-11-22
      DOI: 10.3390/coatings11111427
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1428: Investigations on the Influence of
           Annealing on Microstructure and Mechanical Properties of Electrodeposited
           Ni-Mo and Ni-Mo-W Alloy Coatings

    • Authors: Chao Zhang, Wudong Si, Yin Wang, Sichao Dai, Da Shu
      First page: 1428
      Abstract: Ni-Mo and Ni-Mo-W coatings were electrodeposited on a stainless steel sheet, and then were annealed at 200, 400, and 600 °C. The effect of annealing heat treatment on the microstructure of Ni-Mo and Ni-Mo-W electrodepositions, their nano-hardness, and tribological properties were investigated. It was revealed that the average crystalline are refined and phase separation are promoted with formation of Mo-W related intermetallic precipitates at temperature exceed 400 °C on account of the co-existence of Mo-W elements within Ni-Mo-W coatings. Annealing heat treatment leads to hardening, and the hardness and elastic module increase significantly. The grain boundary (GB) relaxation and hard precipitated intermetallic particles are responsible for the annealing-induced hardening for ≤400 °C annealed and 600 °C annealed Ni-Mo-W coatings, respectively. In addition, both adhesive wear and abrasive wear are observed for coatings, and abrasive wear becomes predominant when annealing temperature up to 600 °C. The wear resistance of coatings is improved eventually by formation of a mixture of lubricated oxides upon annealing at 600 °C and the enhancement of H/E ratio for ≤400 °C annealed Ni-Mo-W coatings.
      Citation: Coatings
      PubDate: 2021-11-22
      DOI: 10.3390/coatings11111428
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1429: On Soliton Solutions of Perturbed
           Boussinesq and KdV-Caudery-Dodd-Gibbon Equations

    • Authors: Muhammad Imran Asjad, Hamood Ur Rehman, Zunaira Ishfaq, Jan Awrejcewicz, Ali Akgül, Muhammad Bilal Riaz
      First page: 1429
      Abstract: Nonlinear science is a fundamental science frontier that includes research in the common properties of nonlinear phenomena. This article is devoted for the study of new extended hyperbolic function method (EHFM) to attain the exact soliton solutions of the perturbed Boussinesq equation (PBE) and KdV–Caudery–Dodd–Gibbon (KdV-CDG) equation. We can claim that these solutions are new and are not previously presented in the literature. In addition, 2d and 3d graphics are drawn to exhibit the physical behavior of obtained new exact solutions.
      Citation: Coatings
      PubDate: 2021-11-22
      DOI: 10.3390/coatings11111429
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1430: Deposition, Morphological, and Mechanical
           Evaluation of W and Be-Al2O3 and Er2O3 Co-Sputtered Films in Comparison
           with Pure Oxides

    • Authors: Mihail Lungu, Cornel Staicu, Flaviu Baiasu, Alexandru Marin, Bogdan Butoi, Daniel Cristea, Oana Gloria Pompilian, Claudiu Locovei, Corneliu Porosnicu
      First page: 1430
      Abstract: Compact and defect-free high melting point oxide strengthened metallic matrix configurations are promising to resolve the hydrogen permeation and brittleness issues relevant to the fusion research community. Previous studies on oxide addition to metallic matrix demonstrated a mitigation in brittleness behavior, while deposition techniques and material configurations are still to be investigated. Thus, here, we report the structural, morphological, and mechanical characterization of metal-oxides thin layers co-deposited by radio frequency (RF)and direct current (DC) magnetron sputtering. A total of six configurations were deposited such as single thin layers of oxides (Al2O3, Er2O3) and co-deposition configurations as metal-oxides (W, Be)—(Al2O3, Er2O3). The study of films roughness by atomic force microscopy (AFM) method show that for Al2O3 metallic-oxides is increased to an extent that could favor gaseous trapping, while co-depositions with Be seem to promote an increased roughness and defects formation probability compared to W co-depositions. Lower elastic modulus on metal-oxide co-depositions was observed, while the indentation hardness increased for Be and decreased for W matrix configurations. These outputs are highly relevant for choosing the proper compact and trap-free configuration that could be categorized as a permeation barrier for hydrogen and furtherly studied in laborious permeation yield campaigns.
      Citation: Coatings
      PubDate: 2021-11-22
      DOI: 10.3390/coatings11111430
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1431: Solution-Processed All-Solid-State
           Electrochromic Devices Based on SnO2/NiO Doped with Tin

    • Authors: Gieun Kim, Songeun Hong, Suho Yoo, Jongwoon Park
      First page: 1431
      Abstract: We investigated the photochromic (PC) and electrochromic (EC) properties of tin-doped nickel oxide (NiO) thin films for solution-processable all-solid-state EC devices. The PC effect is shown to be enhanced by the addition of Sn into the precursor NiO solution. We fabricated an EC device with six layers—ITO/TiO2 (counter electrode)/SnO2 (ion-conducting layer)/SiO2 (barrier)/NiO doped with tin (EC layer)/ITO—by a hybrid fabrication process (sputtering for ITO and TiO2, sol–gel spin coating for SnO2 and NiO). The EC effect was also observed to be improved with the Sn-doped NiO layer. It was demonstrated that UV/O3 treatment is one of the critical processes that determine the EC performance of the hydroxide ion-based device. UV/O3 treatment generates hydroxide ions, induces phase separation from a single mixture of SnO2 and silicone oil, and improves the surface morphology of the films, thereby boosting the performance of EC devices. EC performance can be enhanced further by optimizing the thickness of TiO2 and SiO2 layers. Specifically, the SiO2 barrier blocks the transport of charges, bringing in an increase in anodic coloration. We achieved the transmittance modulation of 38.3% and the coloration efficiency of 39.7 cm2/C. We also evaluated the heat resistance of the all-solid-state EC device and found that the transmittance modulation was decreased by 36% from its initial value at 100 °C. Furthermore, we demonstrated that a large-area EC device can be fabricated using slot-die coating without much compromise on EC performance.
      Citation: Coatings
      PubDate: 2021-11-22
      DOI: 10.3390/coatings11111431
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1432: Application of Auricularia cornea as a Pork
           Fat Replacement in Cooked Sausage

    • Authors: Yuan Fu, Long Zhang, Mengdi Cong, Kang Wan, Guochuan Jiang, Siqi Dai, Liyan Wang, Xuejun Liu
      First page: 1432
      Abstract: The effect of Auricularia cornea (AC) as an alternative for pork fat on the physico-chemical properties and sensory characteristics of cooked sausage were evaluated. The results indicated that replacement of pork fat with AC led to a significant increase in the protein, ash, moisture, cooking loss, water holding capacity, springiness, and chewiness, especially isoleucine, leucine, proline, palmitic, palmitoleic, oleic, and arachidonic acids of the sausages. In contrast, AC reduced the level of fat (12.61%–87.56%) and energy (5.76%–56.40%) of the sausages. In addition, AC led to the mild lightness, yellowness, whiteness, and soft texture, while it did not affect the water activity of the sausages. From the sensory point of view, all sausages were judged acceptable, and the substitution of 75% of pork fat by AC exhibited best sensory characteristics. In a word, AC is a promising food to partially replace the pork fat in sausages.
      Citation: Coatings
      PubDate: 2021-11-22
      DOI: 10.3390/coatings11111432
      Issue No: Vol. 11, No. 11 (2021)
       
 
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