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: 453)
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)
Adsorption     Hybrid Journal   (Followers: 5)
Advanced Energy and Sustainability Research     Open Access   (Followers: 8)
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 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: 2)
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 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 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 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)
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)
Carpathian Journal of Electronic and Computer Engineering     Open Access  
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 6)
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)
Coal Science and Technology     Full-text available via subscription   (Followers: 4)
Coastal Engineering     Hybrid Journal   (Followers: 14)
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: 18)
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: 335)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 279)
Composites Part B : Engineering     Hybrid Journal   (Followers: 312)
Composites Part C : Open Access     Open Access   (Followers: 3)
Composites Science and Technology     Hybrid Journal   (Followers: 247)
Comptes Rendus : Mécanique     Open Access   (Followers: 2)
Computation     Open Access   (Followers: 1)
Computational Geosciences     Hybrid Journal   (Followers: 20)
Computational Optimization and Applications     Hybrid Journal   (Followers: 11)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 6)
Computer Science and Engineering     Open Access   (Followers: 21)

        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  [238 journals]
  • Coatings, Vol. 11, Pages 1268: Annealing Effect on the Contact Angle,
           Surface Energy, Electric Property, and Nanomechanical Characteristics of
           Co40Fe40W20 Thin Films

    • Authors: Wen-Jen Liu, Yung-Huang Chang, Chi-Lon Fern, Yuan-Tsung Chen, Tian-Yi Jhou, Po-Chun Chiu, Shih-Hung Lin, Ko-Wei Lin, Te-Ho Wu
      First page: 1268
      Abstract: This study investigated Co40Fe40W20 single-layer thin films according to their corresponding structure, grain size, contact angle, and surface energy characteristics. Co40Fe40W20 alloy thin films of different thicknesses, ranging from 10 to 50 nm, were sputtered on Si(100) substrates by DC magnetron sputtering. The thin films were annealed under three conditions: as-deposited, 250 °C, and 350 °C temperatures, respectively. The Scherrer equation was applied to calculate the grain size of Co40Fe40W20 thin films. The results show that the grain size of CoFe(110) increased simultaneously with the increase of post-annealing temperature, suggesting that the crystallinity of Co40Fe40W20 thin films increased with the post-annealing temperature. Moreover, the contact angles of all Co40Fe40W20 thin films were all less than 90°, suggesting that Co40Fe40W20 thin films show changes in the direction of higher hydrophilicity. However, we found that their contact angles decreased as the grain size of CoFe increased. Finally, the Young equation was applied to calculate the surface energy of Co40Fe40W20 thin films. After post-annealing, the surface energy of Co40Fe40W20 thin films increased with the rising post-annealing temperature. This is the highest value of surface energy observed for 350 °C. In addition, the surface energy increased as the contact angle of Co40Fe40W20 thin films decreased. The high surface energy means stronger adhesion, allowing the formation of multilayer thin films with magnetic tunneling junctions (MTJs). The sheet resistance of the as-deposited and thinner CoFeW films is larger than annealed and thicker CoFeW films. When the thickness is from 10 nm to 50 nm, the hardness and Young’s modulus of the CoFeW film also show a saturation trend.
      Citation: Coatings
      PubDate: 2021-10-20
      DOI: 10.3390/coatings11111268
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1269: Corrosion Law of Metal Pipeline in Tahe
           Oilfield and Application of New Materials

    • Authors: Xiaolong Shi, Zhi Zhang, Lanjie Wu, Xincai Li, Zhenwu Zhang
      First page: 1269
      Abstract: Frequent corrosion perforation of metal pipes severely restricts oil and gas fields’ safety production and increases maintenance costs. Therefore, it is imminent to change the characteristics of metal materials fundamentally. In this paper, taking the metal pipe of Northwest Oil and Gas Field in China as an example, for the corrosion environment with high concentrations of H2S, CO2, H2O, Cl−, and O2, the main factors leading to corrosion are analyzed, the corrosion rules and optical materials of the pipe under different environmental and operating conditions are figured out, and the corrosion resistance of new pipes materials is evaluated. The main conclusions are as follows: (1) In the environment of the CO2–H2O–Cl− strong scouring system, electrochemical corrosion dominates, and the corrosion morphology is mainly groove-like corrosion and ulcer-like corrosion; (2) The H2S content affects the incubation period and development period of pipe corrosion; (3) Through the two optimization directions of 20# steel refining and material alloying, BX245-1Cr pipe material has been developed. At present, the application of this pipe material has relatively better results.
      Citation: Coatings
      PubDate: 2021-10-20
      DOI: 10.3390/coatings11111269
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1270: Eco-Friendly Protective Coating to Extend
           the Life of Art-Works and Structures Made in Porous Stone Materials

    • Authors: Mariateresa Lettieri, Maurizio Masieri, Marika Aquaro, Debora Dilorenzo, Mariaenrica Frigione
      First page: 1270
      Abstract: The application of hydrophobic treatments to stone surfaces is the most common proven method to prevent, or at least limit, the degradation of stone-made constructions and artworks brought about by the ingress and action of water, in particular in the case of very porous stone materials. To avoid the use of protective products containing harmful solvents, new green products have been proposed. In this paper, an eco-friendly hydrophobic coating, based on a fluorine polymer dispersed in water, was deeply analyzed to evaluate its protective properties, especially for very porous stone substrates. To this aim, a wide characterization of treated and untreated Lecce stone elements, i.e., a stone typical of the Apulia region, was carried out to assess the optimum required amount, the effectiveness and the protective capability, even against graffiti staining, of the green hydrophobic treatment, still allowing the stone to retain adequate vapor permeability. The efficacy of the eco-friendly product was analyzed also after a short time (four weeks) of outdoor exposure. Suitable performance and short-term durability of the green hydrophobic coating were found, comparable or even greater than those reported in the current literature for other widespread commercial products, confirming the capability of the product to preserve porous stone surfaces even in absence of solvents in its formulation. The study also allowed to experiment with the “contact sponge” test as an appropriate method for evaluating the water absorption properties of the stone.
      Citation: Coatings
      PubDate: 2021-10-20
      DOI: 10.3390/coatings11111270
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1271: Efficiency of Application of (Mo,
           Al)N-Based Coatings with Inclusion of Ti, Zr or Cr during the Turning of
           Steel of Nickel-Based Alloy

    • Authors: Alexey Vereschaka, Filipp Milovich, Nikolay Andreev, Nikolay Sitnikov, Islam Alexandrov, Alexander Muranov, Maxim Mikhailov, Aslan Tatarkanov
      First page: 1271
      Abstract: The article compares the properties of multilayer composite wear-resistant coatings of Zr–ZrN–(Zr, Mo, Al)N, Ti–TiN–(Ti, Mo, Al)N, and Cr–CrN–(Cr, Mo, Al)N. The investigation was focused on hardness, resistance to fracture during scratch tests, elemental composition, and structure of the coatings. Experiments were carried out to study the wear resistance of coated carbide tools during the turning of 1045 steel and of NiCr20TiAl heat-resistant nickel alloy. With the elemental compositions identical in the content of molybdenum (Mo) and aluminium (Al), identical thicknesses and nanolayer periods of λ, the coatings being studied demonstrated a noticeable difference in wear resistance. Both during the turning of steel and nickel-based alloy, the highest wear resistance was detected for tools with the Zr–ZrN–(Zr, Mo, Al)N coating (the tool life was 3–5 times higher than for uncoated tools). The good wear resistance of the Zr–ZrN–(Zr, Mo, Al)N coating may be related to the optimal combination of hardness and plasticity and the active formation of molybdenum oxide (MoO3) on the coating surface during the cutting, with good tribological and protective properties.
      Citation: Coatings
      PubDate: 2021-10-20
      DOI: 10.3390/coatings11111271
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1272: Fire Performance of Intumescent Waterborne
           Coatings with Encapsulated APP for Wood Constructions

    • Authors: Atif Hussain, Véronic Landry, Pierre Blanchet, Doan-Trang Hoang, Christian Dagenais
      First page: 1272
      Abstract: In this work, intumescent coatings were prepared for protection of wood from fire. The fire-retardant chemical ammonium polyphosphate (APP) is known to have poor resistance to water and high humidity as it is hygroscopic in nature. To improve the water resistance, durability and fire resistance of the intumescent coating, APP was modified using a hybrid organic-inorganic polysiloxane encapsulation shell prepared by the sol–gel method. The physical and chemical properties of the intumescent mix containing microencapsulated ammonium polyphosphate (EAPP) particles were characterized by X-ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), water absorption, dynamic vapor sorption (DVS) and thermogravimetric analysis (TGA). The EAPP mix showed 50% reduction in water absorption, 75% reduction in water vapor sorption and increased thermal stability when compared to the APP mix. The intumescent coatings were applied on wood samples, and their fire performance was evaluated using a cone calorimeter test. The intumescent coatings containing EAPP mix showed better fire retarding properties with longer time to ignition, lower heat release rate and shorter heat release peak when compared to the coating without EAPP mix. The prepared intumescent coating shows higher resistance to water and moisture, and it has great potential to be used in bio-based construction industry for enhancing the fire resistance of wood.
      Citation: Coatings
      PubDate: 2021-10-20
      DOI: 10.3390/coatings11111272
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1273: In Silico Modeling as a Perspective in
           Developing Potential Vaccine Candidates and Therapeutics for COVID-19

    • Authors: Barghash, Fawzy, Chandrasekar, Singh, Katha, Mandour
      First page: 1273
      Abstract: The potential of computational models to identify new therapeutics and repurpose existing drugs has gained significance in recent times. The current ‘COVID-19′ pandemic caused by the new SARS CoV2 virus has affected over 200 million people and caused over 4 million deaths. The enormity and the consequences of this viral infection have fueled the research community to identify drugs or vaccines through a relatively expeditious process. The availability of high-throughput datasets has cultivated new strategies for drug development and can provide the foundation towards effective therapy options. Molecular modeling methods using structure-based or computer-aided virtual screening can potentially be employed as research guides to identify novel antiviral agents. This review focuses on in-silico modeling of the potential therapeutic candidates against SARS CoVs, in addition to strategies for vaccine design. Here, we particularly focus on the recently published SARS CoV main protease (Mpro) active site, the RNA-dependent RNA polymerase (RdRp) of SARS CoV2, and the spike S-protein as potential targets for vaccine development. This review can offer future perspectives for further research and the development of COVID-19 therapies via the design of new drug candidates and multi-epitopic vaccines and through the repurposing of either approved drugs or drugs under clinical trial.
      Citation: Coatings
      PubDate: 2021-10-20
      DOI: 10.3390/coatings11111273
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1274: Prediction and Analysis of the Grit
           Blasting Process on the Corrosion Resistance of Thermal Spray Coatings
           Using a Hybrid Artificial Neural Network

    • Authors: Ye, Xu, Pan, Yin, Hu, Wu, Li, Li
      First page: 1274
      Abstract: Grit blasting as a pretreatment process for the substrate surface before thermal spraying is of great importance for assuring the service performance of thermal spraying coatings. In this work, a novel hybrid artificial neural network (ANN) was presented to optimize the grit blasting process to improve the structural properties and corrosion resistance performance of thermal spraying coatings. Different grit blasting process parameters were combined to pretreat the substrate surface, and the corresponding surface roughness, interface adhesion strength and corrosion resistance performance were obtained. Hence, a backpropagation (BP) neural network model optimized by the genetic algorithm (GA) was presented to address the poor regression roughness and accuracy of the traditional fitting models; the grit blasting processing parameters were utilized as the inputs for the GA–BP model; the structural properties and the corrosion resistance performance were used as the outputs. The correlation coefficient R reached and exceeded 0.90, and three error values were less than 1.75 on the prediction of the service performance of random samples. All these indicators demonstrated convincingly that the obtained hybrid artificial neural network models possessed good prediction performance, and this innovative and time-saving grit blasting process optimization approach could be potentially employed to improve the comprehensive service performance of thermal spraying coatings.
      Citation: Coatings
      PubDate: 2021-10-20
      DOI: 10.3390/coatings11111274
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1275: The Impact of the Mechanical Modification
           of Bacterial Cellulose Films on Selected Quality Parameters

    • Authors: Betlej, Salerno-Kochan, Jankowska, Krajewski, Wilkowski, Rybak, Nowacka, Boruszewski
      First page: 1275
      Abstract: This study investigated the effect of the homogenization of bacterial cellulose particles and their reintegration into a membrane on the mechanical and physical parameters of the films produced from them in relation to films made of native cellulose (not subjected to the homogenization process). Bacterial cellulose was obtained from a culture of microorganisms forming a conglomerate of bacteria and yeast, called SCOBY. The research has shown that the mechanical modification of bacterial cellulose contributes to an increase in the elongation of the material. Modified polymer films were characterized by a higher Young’s modulus and a much higher breaking force value compared to native cellulose. The mechanical modification of cellulose contributed to an increase in hygroscopicity and changes in water vapor permeability. The obtained results may provide significant information on the methods of modifying bacterial cellulose, depending on its various applications.
      Citation: Coatings
      PubDate: 2021-10-20
      DOI: 10.3390/coatings11111275
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1276: Deicing Property of Asphalt Mixture
           Containing Steel Wool Fiber by Electromagnetic Induction Heating

    • Authors: Cunhong Xu, Kejin Wang, Kehong Li, Youjie Zong
      First page: 1276
      Abstract: Snow and ice is one of the main problems affecting road safety in winter. In order to effectively remove the snow and ice of covering the pavement, the deicing property of asphalt mixture pavement containing steel wool fiber was introduced and investigated by electromagnetic induction heating. Based on the deicing mechanism of Faraday’s law of electromagnetic induction and the Joule’s law, the influences factors affecting deicing efficiency, including length and content of steel wool fiber, ice thickness, output current and ambient temperature were analyzed. Meanwhile, the grey correlation entropy analysis and t-test between the average deicing rate and various influencing factors were explored. BP neural network prediction models of predicting change laws of average deicing rate under different influencing factors were established. The results indicate that the average deicing rate of asphalt mixture adding steel wool fiber increases with the increase of length and content of steel wool fiber. The influence degree of each factor for the average deicing rate is in order as follows: steel wool fiber content, steel wool fiber length, output current, ambient temperature and ice thickness. BP neural network has high accuracy in predicting average deicing rate under various influencing factors and the better simulation results. It is of significance to apply the technology of “electromagnetic induction heating & steel wool fiber” to the efficient deicing of asphalt pavement.
      Citation: Coatings
      PubDate: 2021-10-21
      DOI: 10.3390/coatings11111276
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1277: Analysis of the Coloring and Antibacterial
           Effects of Natural Dye: Pomegranate Peel

    • Authors: Aicha Bouaziz, Dorra Dridi, Sondes Gargoubi, Souad Chelbi, Chedly Boudokhane, Abderraouf Kenani, Sonia Aroui
      First page: 1277
      Abstract: This work aims to conduct an eco-friendly textile finishing process by applying agricultural by-products as a dye for the finishing of polyamide fabrics. A natural dye was obtained from pomegranate peel extract. Polyamide fabrics were dyed at different conditions, and four mordanting agents were tested. The finished fabrics were analyzed in terms of CIE L, a, b and color yield (K/S) values, as well as washing fastness, rubbing fastness, light fastness and antibacterial activity. Results show that pomegranate peel extract could dye polyamide fabrics. The rubbing and washing fastness of the finished samples was good. The light fastness was fair, and its antibacterial efficiency against the tested bacteria was good.
      Citation: Coatings
      PubDate: 2021-10-21
      DOI: 10.3390/coatings11111277
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1278: Corrosion Behavior of AA2055
           Aluminum-Lithium Alloys Anodized in the Presence of Sulfuric Acid Solution
           

    • Authors: Pedro Oliver Samaniego-Gámez, Facundo Almeraya-Calderon, Erick Maldonado-Bandala, Jose Cabral-Miramontes, Demetrio Nieves-Mendoza, Javier Olguin-Coca, Luis Daimir Lopez-Leon, Luis G. Silva Vidaurri, Patricia Zambrano-Robledo, Citlalli Gaona-Tiburcio
      First page: 1278
      Abstract: The aim of this work was to evaluate the corrosion behavior of the AA2055 Aluminum-lithium alloy anodized in a sulfuric acid (H2SO4) bath, varying the current density of 0.19 and 1 A·cm−2 and why the sealing solution was water (H2O) and sodium dichromate (Na2Cr2O7). Anodized samples were exposed to a 10 vol.% H2SO4 solution and the electrochemical technique used was electrochemical impedance spectroscopy. Scanning electron microscopy and X-ray photoelectron spectroscopy were employed to characterization of the anodizing layer, determinate morphology and thickness of coatings. The Na2Cr2O7 sealing solution tends to increase the charge transfer resistance and produces a more homogeneous and compact passive oxide layer, and imparts a corrosion inhibition protection to the AA2055. SEM observations indicated that the morphology and thickness of the anodic films formed on AA2055 aluminum-lithium alloy anodized have the best results for both current densities.
      Citation: Coatings
      PubDate: 2021-10-21
      DOI: 10.3390/coatings11111278
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1279: Functional Polymeric Coatings for CsI(Tl)
           Scintillators

    • Authors: Carotenuto, Longo, Nenna, Coscia, Palomba
      First page: 1279
      Abstract: The handling of inorganic scintillators (e.g., alkali metal halides) can benefit from the availability of polymeric materials able to adhere to their surface. Polymeric materials, such as epoxy resins, can act as protective coatings, as adhesives for photodiodes to be connected with the scintillator surface, and as a matrix for functional fillers to improve the optical properties of scintillators. Here, the optical properties of two epoxy resins (E-30 by Prochima, and Technovit Epox by Heraeus Kulzer) deposited on the surface of a scintillator crystal made of CsI(Tl) were investigated, in order to improve the detection of high-energy radiation. It is found that these resins are capable of adhering to the surface of alkali metal halides. Adhesion, active at the epoxy–CsI(Tl) interface, can be explained on the basis of Coulomb forces acting between the ionic solid surface and an ionic intermediate of synthesis generated during the epoxy setting reaction. Technovit Epox showed higher transparency, and it was also functionalized by embedding white powdered pigments (PTFE or BaSO4) to achieve an optically reflective coating on the scintillator surface.
      Citation: Coatings
      PubDate: 2021-10-21
      DOI: 10.3390/coatings11111279
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1280: Influence of α-Al2O3 Template and Process
           Parameters on Atomic Layer Deposition and Properties of Thin Films
           Containing High-Density TiO2 Phases

    • Authors: Kristel Möls, Lauri Aarik, Hugo Mändar, Aarne Kasikov, Taivo Jõgiaas, Aivar Tarre, Jaan Aarik
      First page: 1280
      Abstract: High-density phases of TiO2, such as rutile and high-pressure TiO2-II, have attracted interest as materials with high dielectric constant and refractive index values, while combinations of TiO2-II with anatase and rutile have been considered promising materials for catalytic applications. In this work, the atomic layer deposition of TiO2 on α-Al2O3 (0 0 0 1) (c-sapphire) was used to grow thin films containing different combinations of TiO2-II, anatase, and rutile, and to investigate the properties of the films. The results obtained demonstrate that in a temperature range of 300–400 °C, where transition from anatase to TiO2-II and rutile growth occurs in the films deposited on c-sapphire, the phase composition and other properties of a film depend significantly on the film thickness and ALD process time parameters. The changes in the phase composition, related to formation of the TiO2-II phase, caused an increase in the density and refractive index, minor narrowing of the optical bandgap, and an increase in the hardness of the films deposited on c-sapphire at TG ≥ 400 °C. These properties, together with high catalytic efficiency of mixed TiO2-II and anatase phases, as reported earlier, make the films promising for application in various functional coatings.
      Citation: Coatings
      PubDate: 2021-10-21
      DOI: 10.3390/coatings11111280
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1281: Plasma Sputtered Tungsten Oxide Thin Film
           on Poly(lactic acid) for Food Packaging Applications

    • Authors: Matteo Pedroni, Espedito Vassallo, Marco Aloisio, Milena Brasca, Hao Chen, Giuseppe Firpo, Francesco Ghezzi, Stefano Morandi, Silvia Maria Pietralunga, Tiziana Silvetti, Tersilla Virgili
      First page: 1281
      Abstract: Biodegradable and bio-derived plastics such as poly(lactic acid) (PLA) are a promising solution to solve the huge environmental and economic issues caused by the enormous consumption of conventional oil-derived polymers, especially in food packaging applications. However, their poor gas barrier properties and high transparency to UV radiation limit their currently commercialization. Therefore, this study is focused on the deposition of tungsten oxide (WOx) thin films on commercial PLA in order to enhance its overall performance. Coatings with different thickness (25, 50 and 100 nm) were deposited by means of radiofrequency (RF) plasma magnetron reactive sputtering. Morphological characterization was carried out with atomic force microscopy (AFM) and scanning electron microscopy (SEM). In order to evaluate surface chemical changes due to plasma treatments, Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis were performed. The PLA/WOx samples demonstrated remarkable improvements both in UV protection and oxygen barrier properties. In particular, light transmittance was reduced by approximately 95% in the UV-B region, 70% in the UV-A region and 50% in the visible region compared to pristine PLA. Regarding oxygen permeation, a reduction of at least 99.9% was achieved. In addition, the PLA/WOx antibacterial properties against Escherichia coli were also investigated, showing a reduction greater than 5 log10 CFU cm−2 after 24 h for the 50 and 100 nm samples. These results demonstrate the potential of WOx thin coating for sustainable food packaging applications.
      Citation: Coatings
      PubDate: 2021-10-21
      DOI: 10.3390/coatings11111281
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1282: Structural Characteristics and Sliding
           Friction Properties of 40CrNiMo Steel after Broadband Laser Hardening

    • Authors: Jia Li, Hongzhi Yan, Songbai Li, Yin Zhang, Pengfei Zhu
      First page: 1282
      Abstract: The surface of 40CrNiMo steel, which is commonly used for the sprag clutch wedge, is prone to wear. In this study, hardening of the matrix material was conducted by broadband-laser scanning at various scanning speeds. The hardness distribution and structure evolution were analyzed along the vertical direction. Characteristics of the hardened layer were explored using scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry. The friction coefficient, wear amount, and wear morphology of sliding friction against GCr15 steel were investigated under various conditions. The results show that the depth of the hardened zone decreases with increasing scanning speed. Under the experimental power and defocus, a laser scanning speed between 700–1020 mm/min can meet the general surface requirements of the sprag clutch wedge. After laser hardening, the main components of the hardened layer included lath-shaped and needle-shaped martensite and retained austenite. In terms of friction and wear, when the relative movement speed was within 300–500 mm/min, the relative movement speed decreased and the normal force increased, which led to an increase in the friction coefficient and its fluctuation, as well as an increase in wear volume of the hardened layer. The wear mechanism of the hardened layer included abrasive wear, adhesive wear, and oxidative wear. Excessive normal force resulted in obvious delamination of the sample. Within the scope of the experiment, the best laser hardening results were obtained with a scanning speed of 800 mm/min.
      Citation: Coatings
      PubDate: 2021-10-21
      DOI: 10.3390/coatings11111282
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1283: A Novel Accelerated Aging Test for Floats
           in a Floating Photovoltaic System

    • Authors: Chun-Kuo Liu, Zhong-Ri Kong, Ming-Je Kao, Teng-Chun Wu
      First page: 1283
      Abstract: Countries around the globe have recently been actively developing a new type of solar power system known as the floating photovoltaic (FPV) system. The FPV system is advantageous in terms of efficiency and is economic; however, the environmental conditions on the surface of water are harsher than on the ground, and regulations or standards of the long-term durability of the float are insufficient. As a result, this study aims to investigate the durability of the float through three types of accelerated aging tests, including the damp heat test, the ozone-aging test, and the ultraviolet (UV) aging test. After the 7-day damp heat test (80 °C/95% RH), the results revealed that four groups of high-density polyethylene (HDPE) extrusion specimens neither produced more oxygen-containing functional groups, according to Fourier-transform infrared (FTIR) spectrum analysis, nor became more easily broken by the tensile test. Furthermore, more oxygen-containing functional groups were produced after the 7-day ozone-aging test (80 °C/95% RH/500 ppm) than the 17-day UV-aging test (60 °C/0% RH/60 kW·h·m−2). On the contrary, UV aging would make HDPE specimens harder and more brittle than ozone aging. To conclude, both ozone- and UV-aging tests can evaluate the durability of the float quickly and efficiently.
      Citation: Coatings
      PubDate: 2021-10-21
      DOI: 10.3390/coatings11111283
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1284: Non-Thermal Reactive N2/He Plasma Exposure
           to Inhibit Epithelial Head and Neck Tumor Cells

    • Authors: Chih-Ying Wu, Jiunn-Der Liao, Chang-Han Chen, Han Lee, Shyh-Hau Wang, Bernard Haochih Liu, Cheng-Yi Lee, Pei-Lin Shao, Enya Li
      First page: 1284
      Abstract: The traditional therapy for head and neck cancer patients has several side effects. Hence, regular follow-up care is usually required. Recently, non-thermal micro-plasma was applied to inactivate cancer cells. Such a physical method provides localized energy and reactive oxygen/nitrogen species (ROS/RNS). In this study, the ability of non-oxygen N2/He micro-plasma to inactivate four pharynx squamous carcinomatous cells, namely SAS, CAL 27, FaDu, and Detroit 562, under different exposure durations is evaluated. The four cell lines were affected with regard to proliferation, reduction, and apoptosis-related DNA damage, implying that the cell medium is critical in plasma–cell interaction. This is expected to be a promising method for head and neck cancer cell suppression through plasma-initiated ROS/RNS species under a suitable exposure time.
      Citation: Coatings
      PubDate: 2021-10-22
      DOI: 10.3390/coatings11111284
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1285: Friction and Wear Behaviors of
           Fe-19Cr-15Mn-0.66N Steel at High Temperature

    • Authors: Shaolong Sheng, Huiling Zhou, Xiaojing Wang, Yanxin Qiao, Hongtao Yuan, Jian Chen, Lanlan Yang, Dongpeng Wang, Zhenguang Liu, Jiasheng Zou, Zhibin Zheng, Jingyong Li
      First page: 1285
      Abstract: The friction and wear behaviors of Fe-19Cr-15Mn-0.66N steel were investigated under applied loads of 5 N and 15 N at the wear-testing temperatures of 300 °C and 500 °C using a ball-on-disc tribometer. The wear tracks were evaluated by scanning electron microscopy (SEM) and laser scanning confocal microscopy (LSCM) to reveal the variation in morphologies. Energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were used to determine the components of oxide layers formed on wear surfaces. The results demonstrated that the oxide layers are favorable for obtaining a low friction coefficient under all conditions. The average friction coefficient decreased with increasing load at 300 °C, while it increased with the increase in applied load at 500 °C. At 300 °C, severe abrasive wear characterized by grooves resulted in a high friction coefficient with 5 N applied, whereas the formation of a denser oxide layer consisting of Cr2O3, FeCr2O4, Fe2O3, etc., and the increased hardness caused by work hardening led to a decrease in friction characterized by mild adhesive wear. At 500 °C, the transformation of Fe2O3 to the relatively softer Fe3O4 and the high production of lubricating Mn2O3 resulted in a minimum average friction coefficient (0.34) when 5 N was applied. However, the softening caused by high temperature weakened the hardening effect, and thus the friction coefficient increased with 15 N applied at 500 °C.
      Citation: Coatings
      PubDate: 2021-10-22
      DOI: 10.3390/coatings11111285
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1286: Optimization of Quantitative Analysis of
           Biofilm Cell from Pipe Materials

    • Authors: Dorota Papciak, Andżelika Domoń, Monika Zdeb, Agata Skwarczyńska-Wojsa, Janusz Konkol
      First page: 1286
      Abstract: The quantitative analysis of biofilm can be used not only to assess the microbiological stability of tap water but also on its basis can assess: the degree of colonization of materials by bacterial cells, the rate of biofilm formation on the surfaces of pipes and determine their composition and number. The article presents the results of research on the development of an effective method of biofilm detachment from the surface of the galvanized steel. The number of biofilm cells was determined by methods: (1) luminometric ATP determination, (2) flow cytometry and (3) heterotrophic plate counts (HPC). The presence of the biofilm was confirmed by SEM and fractal analysis. The analysis of the obtained results showed that the most effective method of detaching the biofilm cells from the galvanized steel surface was the mechanical separation with a sterile cotton swab. The variant with the use of a sterile swab enables rapid collection of the biofilm from the surface of the ducts forming internal installations or water supply networks. Due to the simplicity and speed of obtaining results, the luminometric ATP measurement has been established as the best method for the quantification of biofilm cells. The results of this study were intended to provide reliable and useful data on the quantification of biofilm cells.
      Citation: Coatings
      PubDate: 2021-10-22
      DOI: 10.3390/coatings11111286
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1287: FEM Research on Welding Thermal Deformation
           of Copper Alloy Sheet and Optimization of Welding Sequence

    • Authors: Mingxin Yuan, Suodong Liu, Hongwei Sun, Yunqiang Gao, Xianling Dai, Weibin Chen
      First page: 1287
      Abstract: To reduce the residual stress and deformation of the copper alloy sheet after welding, and improve the welding quality of the copper alloy sheet, the finite element method (FEM) research on welding thermal deformation and welding sequence optimization was carried out. First, a finite element model of copper alloy sheet welding was established based on ANSYS, the mechanical property parameters of the model at high temperature were determined, and the thermal–structural coupling calculation was performed on the model. Then, the change trend and magnitude of the residual stress and deformation of the model after welding were analyzed. Finally, different welding sequence schemes were designed, and numerical simulation calculations were carried out. The results of the welding sequence solution show that the change trend of the residual stress after welding of the base metal under different welding sequences is basically the same; repeated heating of the base metal at the same position causes large residual stress; the weldment vertical plate is subjected to opposing forces in the x-axis and y-axis directions at the same time. Among four welding schemes, the welding scheme that alternately welds symmetrically from the start and end positions of the weld seam to the middle position of the plate causes the least welding deformation. Compared with the other three schemes, its deformation reduces by 26.6%, 18.3%, and 19.4%, respectively.
      Citation: Coatings
      PubDate: 2021-10-23
      DOI: 10.3390/coatings11111287
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1288: Preparation of Wear-Resistant Coating on
           Ti6Al4V Alloy by Cold Spraying and Plasma Electrolytic Oxidation

    • Authors: Mingzeng Shao, Wei Wang, Hongbo Yang, Xueer Zhang, Xiaomei He
      First page: 1288
      Abstract: In order to improve the wear resistance of Ti6Al4V alloy, the alloy was first coated with alumina-reinforced aluminum coating (CS-coating) by cold spraying, and then the alloy with CS-coating was processed by plasma electrolytic oxidation (PEO) under unipolar mode and soft sparking mode, respectively, to prepare wear-resistant PEO coatings. For comparison, Ti6Al4V alloy without CS-coating was also subjected to PEO treatment. The microstructure, phase composition, hardness, and wear resistance of the PEO coatings formed on Ti6Al4V alloy with and without CS-coating were investigated. The results revealed that PEO coatings formed on Ti6Al4V alloy with CS-coating under soft sparking mode contained more α-Al2O3, possessed larger thickness, more compact microstructure, and higher microhardness than that formed under unipolar mode. The PEO coating formed on Ti6Al4V substrate was mainly composed of TiO2 and had pores and cracks. Among all these coatings, PEO coating formed on Ti6Al4V alloy with CS-coating under soft sparking mode exhibited the best wear resistance with a wear rate of 1.18 × 10−5 mm3/(Nm), which was only 15.28% of that of the Ti6Al4V substrate. The investigation indicated that the combination of cold spraying and PEO under soft sparking mode is a promising technique for improving the wear resistance of titanium alloy.
      Citation: Coatings
      PubDate: 2021-10-23
      DOI: 10.3390/coatings11111288
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1289: The Effect of Heat Treatment on the
           Microstructure and Phase Composition of Plasma Sprayed Al2O3 and
           Al2O3-TiO2 Coatings for Applications in Biomass Firing Plants

    • Authors: Airingas Šuopys, Liutauras Marcinauskas, Viktorija Grigaitienė, Romualdas Kėželis, Mindaugas Aikas, Rolandas Uscila, Simona Tučkutė, Martynas Lelis
      First page: 1289
      Abstract: This study presents the thermal and chemical resistance of plasma-sprayed Al2O3 and Al2O3 doped with 13 wt.% of TiO2 coatings and their suitability for the fire grate of straw pellet furnaces. Coatings were deposited on steel substrates using direct current atmospheric pressure plasma spraying. The surface structure, elemental, and phase composition of formed coatings were analyzed before and after the thermal treatment, imitating natural application conditions. For the experiment, the annealing temperature was 500 °C for twenty-five cycles (80 min each). It was found that the steel substrate oxidized after five thermal cycles, and the formation of iron oxides was observed. The elemental composition of the Al2O3 and Al2O3-13 wt.% TiO2 coatings remained unchanged even after 25 cycles of heat treatment. The X-ray diffraction (XRD) results revealed that the alpha-Al2O3 to gamma-Al2O3 phase ratio in the Al2O3-TiO2 coating was reduced by only 8.7% after 25 cycles.
      Citation: Coatings
      PubDate: 2021-10-24
      DOI: 10.3390/coatings11111289
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1290: Annealing Studies of Copper Indium Oxide
           (Cu2In2O5) Thin Films Prepared by RF Magnetron Sputtering

    • Authors: Giji Skaria, Ashwin Kumar Saikumar, Akshaya D. Shivprasad, Kalpathy B. Sundaram
      First page: 1290
      Abstract: Copper indium oxide (Cu2In2O5) thin films were deposited by the RF magnetron sputtering technique using a Cu2O:In2O3 target. The films were deposited on glass and quartz substrates at room temperature. The films were subsequently annealed at temperatures ranging from 100 to 900 °C in an O2 atmosphere. The X-ray diffraction (XRD) analysis performed on the samples identified the presence of Cu2In2O5 phases along with CuInO2 or In2O3 for the films annealed above 500 °C. An increase in grain size was identified with the increase in annealing temperatures from the XRD analysis. The grain sizes were calculated to vary between 10 and 27 nm in films annealed between 500 and 900 °C. A morphological study performed using SEM further confirmed the crystallization and the grain growth with increasing annealing temperatures. All films displayed high optical transmission of more than 70% in the wavelength region of 500–800 nm. Optical studies carried out on the films indicated a small bandgap change in the range of 3.4–3.6 eV during annealing.
      Citation: Coatings
      PubDate: 2021-10-24
      DOI: 10.3390/coatings11111290
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1291: Exploring Emerging Technologies with
           Analysis of Bibliographic Data Focused on Plasma Surface Treatment

    • Authors: Youbean Kim
      First page: 1291
      Abstract: Research trends and emerging technologies were explored through the Web of Science (WoS) literature of the last decade in relation to plasma technology, especially plasma surface treatment, widely used in all industries. For this, a network analysis using country and author keywords and emerging technology search algorithms, with regard to novelty, fast growth and impact, were used. As a result, we derived 40 keywords in terms of novelty and fast growth. Additionally, with these keywords, we traced the impact based on the citation relationships. Finally, nine keywords which were analyzed to contain many new technological issues were identified by deriving the author keywords included in the relevant documents. It is expected that the new technology fields derived from this paper can contribute to establishing a preemptive R&D strategy.
      Citation: Coatings
      PubDate: 2021-10-25
      DOI: 10.3390/coatings11111291
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1292: Significance of Synthetic Cilia and
           Arrhenius Energy on Double Diffusive Stream of Radiated Hybrid Nanofluid
           in Microfluidic Pump under Ohmic Heating: An Entropic Analysis

    • Authors: Najma Saleem, Sufian Munawar
      First page: 1292
      Abstract: This study investigates the thermal aspects of magnetohydrodynamic double diffusive flow of a radiated Cu-CuO/Casson hybrid nano-liquid through a microfluidic pump in the presence of electroosmosis effects. Shared effects of the Arrhenius activation energy and the Joule heating on the intended liquid transport are also incorporated. The inner wall of the pump is covered with electrically charged fabricated cilia mat that facilitates flow actuation and micro-mixing process. The governing equations for the proposed problem are simplified by utilizing the Debye-Hückel and lubrication approximations. The numerical solutions are calculated with the aid of shooting technique. The analysis reports that the substantial effects of electroosmosis contribute an important role in cooling process. Existence of electric double layer stimulates an escalation in liquid stream in the vicinity of the pump surface. The Arrhenius energy input strengthens the mass dispersion and regulates the thermal treatment. The proposed geometry delivers a deep perception that fabricated cilia in electroosmotic pumps are potential pharmaceutical micromixers for an effective flow and minimum entropy generation rate.
      Citation: Coatings
      PubDate: 2021-10-25
      DOI: 10.3390/coatings11111292
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1293: A Novel Colorimetric Chemosensor Based on
           Ferene-S-Conjugated Silver Nanoparticles for Selective Recognition of Fe2+
           

    • Authors: Azeem Ullah, Perveen Fazil, Gul Rukh, Munira Taj Muhammad, Muhammad Rahim, Muhammad Ateeq, Rozina Khattak, Muhammad Sufaid Khan, Ola A. Abu Ali, Dalia I. Saleh
      First page: 1293
      Abstract: Ferene is the most commonly used chromogenic agent for the determination of serum iron in blood. In this work we have successfully synthesized Ferene-S-conjugated silver nanoparticles (Ferene-S-AgNPs) for the first time characterized by UV-visible, Fourier-Transform Infrared Spectroscopy (FTIR), and Matrix-Assisted Laser Desorption/Ionization-Time Of Flight (MALDI-TOF) mass spectrometry techniques. Particle size of the synthesized nanoparticles was determined by atomic-force microscopy and scanning electron microscopy techniques with size ranges from 10–90 nm in diameter. Ferene-S-AgNPs were explored for their chemosensing potential with various metal ions such as Sb3+, Pb2+, Ca2+, Fe2+, K+, Co2+, Ba2+, V5+, Cu+, Cd2+, Hg2+, Ni2+, Cu2+, Fe3+, Mg2+, Mn2+, Al3+, and Cr3+. Ferene-S-AgNPs were found to show selective quenching effects and slight bathochromic shifts to the surface plasmon resonance absorption band after treatment with Fe2+. Furthermore, the developed chemosensor also exhibited substantial selectivity towards Fe2+ in the presence of other competitive ions. We observed that Ferene-S-AgNPs mimic the selectivity of the parent compound of Ferene towards Fe2+. The system obeyed Beer’s law over concentration ranges of 110–190 nM. The detection limit was found to be 110 nM.
      Citation: Coatings
      PubDate: 2021-10-25
      DOI: 10.3390/coatings11111293
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1294: Thin Al2O3 Coatings Produced by
           Electrochemical Method, Subjected to Thermo-Chemical Treatment

    • Authors: Mateusz Niedźwiedź, Władysław Skoneczny, Marek Bara, Grzegorz Dercz
      First page: 1294
      Abstract: The article presents the effect of the anodizing parameters, as well as the thermo-chemical treatment, of Al2O3 layers produced on an aluminum alloy on the characterization of structure, geometrical structure of the surface (SGS), the thickness of the oxide layers, the phase composition, and their microhardness. The oxide layers were produced by the method of direct current anodizing in a three-component electrolyte. Then, thermo-chemical treatment was carried out in distilled water and aqueous solutions of sodium dichromate and sodium sulphate. The anodizing parameters and compounds for the thermo-chemical treatment were selected on the basis of Hartley’s plans. The research showed the effect of anodizing parameters on the thickness of the Al2O3 layers and the increase in the thickness of the layers as a result of the thermo-chemical treatment. The research showed a significant increase in the microhardness of the layers as a result of thermo-chemical treatment and its influence on the phase composition of Al2O3 layers. A significant influence of the thermo-chemical treatment on the geometrical structure of the surface was also found.
      Citation: Coatings
      PubDate: 2021-10-25
      DOI: 10.3390/coatings11111294
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1295: Synthesis and Photonics Applications of
           Afzelechin Conjugated Silver Nanoparticles

    • Authors: Shahid Ali, Muhammad Rahim, Perveen Fazil, Malik Shoaib Ahmad, Azeem Ullah, Muhammad Raza Shah, Gul Rukh, Muhammad Ateeq, Rozina Khattak, Muhammad Sufaid Khan, Ola A. Abu Ali, Dalia I. Saleh
      First page: 1295
      Abstract: The silver nanoparticles were synthesized, functionalized with afzelechin and characterized using UV-Visible spectroscopy. A difference of 20 nm was observed in surface plasmon resonance of bare and functionalized silver nanoparticles which indicates afzelechin conjugation with silver nanoparticles. The atomic force microscopy (AFM) technique was used for the determination of the size and morphology of synthesized silver nanoparticles. The afzelechin conjugated silver nanoparticles were spherical and their sizes ranged from 3 to 10 nm with an average size of 8 nm while the bare silver nanoparticles were also spherical and their sizes ranged from 3 to 10 nm with an average size of 6 nm. The average sizes were also calculated by fitting their UV-Visible absorption spectra. Fitting is based on the Mie and Mie Gans models, which deduced that afzelechin conjugated silver nanoparticles were 96.5% spherical and 3.5% spheroidal with an average size of 5 nm while bare silver nanoparticles were 100% spherical with an average size of 4 nm. Both the fitting model as well as the AFM results showed a difference of 3 nm between the sizes of afzelechin conjugated silver nanoparticles while 2 nm differences was observed for bare silver nanoparticles. The band gap energy of afzelechin conjugated silver nanoparticles and bare silver nanoparticles were calculated via Tauc’s equation and were found to be 5.1 eV and 5.4 eV, respectively. A difference of 0.3 eV was observed in band gap energies of afzelechin conjugated silver nanoparticles and bare silver nanoparticles.
      Citation: Coatings
      PubDate: 2021-10-25
      DOI: 10.3390/coatings11111295
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1296: Theoretical Investigation on the Friction
           Behavior of Bio-Inspired Hard-Soft-Integrated Materials

    • Authors: Mi Wang, Wei Yang, Hao Cui, Shu-Chen Yang, Zhen-Ning Liu, Guo-Long Lu
      First page: 1296
      Abstract: Structural biological materials with integrated soft and hard phases are ubiquitous in nature. Over recent decades, bio-inspired hard-soft-integrated materials (BHSIMs) have shown excellent mechanical properties of drag reduction and abrasion resistance. This work is proposed to investigate the friction behaviors of BHSIMs via theoretical modeling, numerical simulation and experimental verification. First, the mathematical model of the friction process was established based on the classic adhesive friction theory. Then, a range of factors in the friction process were examined by simulation and the respective friction coefficients were discussed. Subsequently bio-inspired materials with integrated soft and hard layers were prepared by 3D printing and their friction coefficients were measured by experiments, which had verified the results of theoretical analyses.
      Citation: Coatings
      PubDate: 2021-10-26
      DOI: 10.3390/coatings11111296
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1297: Cross-Scale Biological Models of Species
           for Future Biomimetic Composite Design: A Review

    • Authors: Wenda Song, Zhengzhi Mu, Zhiyan Zhang, Yufei Wang, Handong Hu, Zhe Ma, Liewei Huang, Ze Wang, Binjie Zhang, Yujiao Li, Shuang Zhang, Bo Li, Junqiu Zhang, Shichao Niu, Zhiwu Han, Luquan Ren
      First page: 1297
      Abstract: The rise in structural performance requirements in engineering is driving the research and development of stronger, stiffer, and lighter materials. However, most traditional artificial materials are unable to meet the needs of modern industrial and technological development. In fact, multifarious creatures in nature are further ahead in their use of structural materials. There is a fairly limited selection of natural structural materials at ambient temperatures. They usually consist of hard and soft phases arranged in a complex hierarchy with characteristic dimensions ranging from nanoscale to macroscale. The resulting materials usually show a nearly perfect combination of strength and toughness integrated with lightweight characteristics. This is exactly what is required of engineering materials. In this review, different biological materials were divided into the following types in terms of structural elements: 1D fibrous structures, 2D layered structures, 3D cellular structures and heterogeneous interface structures. For each structural element, corresponding structure components and mechanical properties of typical organisms were well described. Abundant sophisticated models of natural biological structures were discussed contrastively. The purpose of this review was to summarize the excellent properties of multi-dimensional biological models with cross-scale features and to reveal the relationship between structure characteristics and function mechanism, which could provide valuable references for the design and optimization of a future biomimetic composite with high mechanical performance. This review is anticipated to not only inspire novel biomimetic design but also offer a window for the deep understanding of existing outstanding structural composites in diversified species, which could provide continuous innovative power for composite renovation in many engineering fields.
      Citation: Coatings
      PubDate: 2021-10-26
      DOI: 10.3390/coatings11111297
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1298: Highly Conductive Mn-Co Spinel Powder
           Prepared by Cu-Doping Used for Interconnect Protection of SOFC

    • Authors: Zhou Jiang, Kui Wen, Chen Song, Taikai Liu, Yong Dong, Min Liu, Changguang Deng, Chunming Deng, Chenghao Yang
      First page: 1298
      Abstract: Mn-Co Spinel is considered as one of the most promising materials for the interconnect protection of solid oxide fuel cells; however, its conductivity is too low to maintain a high cell performance as compared with cathode materials. Element doping is an effective method to improve the spinel conductivity. In this work, we proposed doping Mn-Co spinel powder with Cu via a solid phase reaction. CuδMn1.5−xCo1.5−yO4 with δ = 0.1, 0.2, 0.3, and x + y = δ was obtained. X-ray diffraction (XRD) and thermogravimetry-differential scanning calorimetry (TG-DSC) were used to evaluate the Cu-doping effect. After sintering at 1000 °C for 12 h, the yield exhibited the best crystallinity, density, and element distribution, with a phase composition of MnCo2O4/CuxMn3−xO4 (x = 1, 1.2, 1.4 or 1.5). X-ray photoelectron spectroscopy (XPS) was used to semi-quantitatively characterize the content changes in element valence states. The areal fraction of Mn2+ and Co3+ was found to decrease when the sintering duration increased, which was attributed to the decomposition of the MnCo2O4 phase. Finally, coatings were prepared by atmospheric plasma spraying with doped spinel powders and the raw powder Mn1.5Co1.5O4. It was found that Cu doping can effectively increase the conductivity of Mn-Co spinel coatings from 23 S/cm to 51 S/cm. Although the dopant Cu was found to be enriched on the surface of the coatings after the conductivity measurement, which restrained the doping effect, Cu doping remains a convenient method to significantly promote the conductivity of spinel coatings for SOFC applications.
      Citation: Coatings
      PubDate: 2021-10-26
      DOI: 10.3390/coatings11111298
      Issue No: Vol. 11, No. 11 (2021)
       
  • Coatings, Vol. 11, Pages 1199: Shape Characterizing of Aggregates Produced
           through Different Crushing Techniques

    • Authors: Ghulam Yaseen, Wesam Salah Alaloul, Imran Hafeez, Abdul Hannan Qureshi
      First page: 1199
      Abstract: The aggregate shape properties produced from the different crushing techniques influence the performance properties of the asphalt mixtures. The objective of this study was to classify the aggregates into spherical, flat, elongated and flat, and elongated shapes, collected from impact crusher and jaw crusher of two sources, and to calculate the shape parameters, such as aspect ratio, shape factor, form factor, sphericity, roundness, and angularity index. In addition, this study also investigated the effects of this classification on the Marshall stability and volumetric properties of asphalt mixtures prepared from the respective shape of aggregates. The results showed that the aggregate of different fractions (passing 37.5 mm and retained on 4.75 mm) produced from the jaw crusher of Margalla quarry showed better shape parameters. The spherical aggregates collected from all crushers showed 20–30% higher Marshall stability of the blends by improving the mechanical and volumetric properties of the asphalt mixtures.
      Citation: Coatings
      PubDate: 2021-09-30
      DOI: 10.3390/coatings11101199
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1200: p-CuO/n-ZnO Heterojunction Structure for
           the Selective Detection of Hydrogen Sulphide and Sulphur Dioxide Gases: A
           Theoretical Approach

    • Authors: Hasan Albargi, Hussein Y. Ammar, Heba M. Badran, Hassan Algadi, Ahmad Umar
      First page: 1200
      Abstract: DFT calculations at the B3LYP/LanL2DZ level of theory were utilized to investigate the adsorption of H2S and SO2 gases on the electronic properties of CuO-ZnO heterojunction structures. The results were demonstrated from the standpoint of adsorption energies (Eads), the density of states (DOS), and NBO atomic charges. The obtained values of the adsorption energies indicated the chemisorption of the investigated gases on CuO-ZnO heterojunction. The adsorption of H2S and SO2 gases reduced the HOMO-LUMO gap in the Cu2Zn10O12 cluster by 4.98% and 43.02%, respectively. This reveals that the Cu2Zn10O12 cluster is more sensitive to the H2S gas than the SO2 gas. The Eads values for SO2 and H2S were −2.64 and −1.58 eV, respectively. Therefore, the Cu2Zn10O12 cluster exhibits a higher and faster response-recovery time to H2S than SO2. Accordingly, our results revealed that CuO-ZnO heterojunction structures are promising candidates for H2S- and SO2-sensing applications.
      Citation: Coatings
      PubDate: 2021-09-30
      DOI: 10.3390/coatings11101200
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1201: Investigations on the Adhesive Contact
           Behaviors between a Viscoelastic Stamp and a Transferred Element in
           Microtransfer Printing

    • Authors: Ling Jiang, Mengjie Wu, Qiuping Yu, Yuxia Shan, Yuyan Zhang
      First page: 1201
      Abstract: Microtransfer printing is a sophisticated technique for the heterogeneous integration of separately fabricated micro/nano-elements into functional systems by virtue of an elastomeric stamp. One important factor influencing the capability of this technique depends on the adhesion between the viscoelastic stamp and the transferred element. To provide theoretical guidance for the control of adhesion in the transfer printing process, a finite element model for the viscoelastic adhesive contact between a polydimethylsiloxane (PDMS) stamp and a spherical transferred element was established, in which the adhesive interaction was modeled by the Lennard-Jones surface force law. Effects of the unloading velocity, preload, and thermodynamic work of adhesion on the adhesion strength, characterized by the pull-off force, were examined for a loading-dwelling-unloading history. Simulation results showed that the unloading path deviated from the loading path due to the viscoelastic property of the PDMS stamp. The pull-off force increased with the unloading velocity, and the increasing ratio was large at first and then became low. Furthermore, the influence of the preload on increasing the pull-off force was more significant under larger unloading velocity than that under smaller unloading velocity. In addition, the pull-off force increased remarkably with the thermodynamic work of adhesion at a fixed maximum approach.
      Citation: Coatings
      PubDate: 2021-09-30
      DOI: 10.3390/coatings11101201
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1202: A Comparative Study of Fabricating IrOx
           Electrodes by High Temperature Carbonate Oxidation and Cyclic Thermal
           Oxidation and Quenching Process

    • Authors: Feifei Huang, Qingrui Wang, Weipeng Wang, Jiangshun Wu, Shuqiang Wang, Yang Zou, Peng Bi, Lei Wen, Ying Jin
      First page: 1202
      Abstract: IrOx electrodes were fabricated by cyclic thermal heating and water quenching (CHQ) process and high temperature carbonate oxidation (HCO), respectively. By examining the E-pH relationship, response rate, potential drift behavior of the fabricated electrodes, the electrodes prepared by CHQ process seemed to show better comprehensive performance. Characterization tests such as scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and electrochemical impedance spectroscopy (EIS) were used to characterize the fabricated IrOx electrodes and find out the reason for the better performance of the electrodes prepared by CHQ process. Morphology tests indicate that the CHQ electrode shows a multi-layer structure with more ion channels, which could provide larger surface area for the H+ response process. Furthermore, combining the XPS, Raman and EIS tests etc., more effective response composition, better crystal quality, and smaller response reaction resistance of surface IrOx film could account for the better performance of the CHQ-fabricated IrOx electrode. The film formation process, H+ response mechanism, as well as the response behavior difference between the two kinds of the electrodes are further elaborated.
      Citation: Coatings
      PubDate: 2021-09-30
      DOI: 10.3390/coatings11101202
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1203: Tribological Performance of Diamond-like
           Nanocomposite Coatings: Influence of Environments and Laser Surface
           Texturing

    • Authors: Sergei M. Pimenov, Evgeny V. Zavedeev, Olga S. Zilova, Alexander P. Lepekhov, Beat Jaeggi, Beat Neuenschwander
      First page: 1203
      Abstract: Diamond-like nanocomposite (DLN) films (a-C:H:Si:O films) are characterized by their unique structure and remarkable tribological properties to be pronounced under various environmental and surface modification conditions. In this paper, we investigated the effects of environments (humid air, water and oil lubrication, elevated temperatures) and laser surface texturing on tribological performance of DLN coatings. Femtosecond laser (wavelength 515 nm) was used for surface texturing. Comparative tests of DLN films sliding against different counterbodies (steel, Si3N4) in humid air and water demonstrated the low-friction and low-wear performance under water, in the absence of chemical interaction of water with the counterbody surface. The wear rates of the film and Si3N4 ball in water, 7.5 × 10−9 and 2.6 × 10−9 mm3/(Nm), were found to be considerably lower than the corresponding values 6.8 × 10−7 and 3.8 × 10−8 mm3/(Nm) in humid air, in spite of higher friction in water-lubricated sliding. Laser surface texturing of DLN films was performed to fabricate microcrater arrays, followed by tribological testing under oil lubrication at different temperatures, from 23 to 100 °C. The lubricated friction performance of laser-textured films was improved at both the room temperature and elevated temperatures. The friction coefficient was reduced from 0.1 (original film) to 0.083 for laser-textured film at room temperature, and then to 0.068 at 100 °C. The nano-/microfriction behavior of laser-structured surface characterized by lower friction forces than the original surface was demonstrated using friction force microscopy in ambient air. The obtained results demonstrate excellent tribological properties of DLN coatings in various environments, which can be further improved by femtosecond-laser-surface texturing.
      Citation: Coatings
      PubDate: 2021-09-30
      DOI: 10.3390/coatings11101203
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1204: Analysis of Additives in Gypsum Coatings
           Based on Melamine, Polycarbonate Salts, Polycarboxylate, and
           Polycarboxylic Acids

    • Authors: Flores Yepes, Serna Jara, Gabarrón, Codes Alcaraz, Pastor Pérez
      First page: 1204
      Abstract: In this paper, we evaluate different gypsum coating additives that are available on the market, which are categorized by their chemical bases. The results will serve as a reference for future investigations of new additive bases in order to improve the properties of gypsum. As such, the objective of the this study is to assess the workability, mechanical behavior, and crystalline structure of calcium sulfate combined with different retarding and fluidifying bases, including melamine bases, which have a compressive strength of 19.32 N/mm2 and handling times with polycarbonate salts of up to 117.58 min. The following study presents the results of standard mechanical tests, analyzing semi-hydrated calcium sulfate (without additives) as a reference, along with the addition of melamines, synthetic melanin polymers, polycarbonate salts, polycarboxylates, and a polycarboxylic acid (citric acid). We already know that the addition of these additives will modify the mechanical properties of calcium sulfate, such as the Shore C surface hardness, flexural strength, modulus of elasticity, and compression resistance, which is the object of this study.
      Citation: Coatings
      PubDate: 2021-09-30
      DOI: 10.3390/coatings11101204
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1205: Physical Experiment and Numerical
           Simulation on Thermal Effect of Aerogel Material for Steel Ladle
           Insulation Layer

    • Authors: Liguang Zhu, Limin Zhang, Caijun Zhang, Zhiqiang Wang, Pengcheng Xiao, Zenxun Liu
      First page: 1205
      Abstract: The selection of lining material for a steel ladle is important to heat preservation of molten steel. Aerogel insulation materials have very low thermal conductivity, however, they are rarely used in steel ladles. In this paper, the application of a new silica aerogel material on the steel ladle insulation layer is tested, and a new calculation method is designed to study its insulation effect. In other words, the ladle wall temperature is obtained by finite element model (FEM) and experiments, then the heat emission from the ladle wall is calculated by the Boltzmann mathematical model according to the ladle wall temperature, and the temperature loss of molten steel is calculated inversely according to the heat emission of ladle wall. Compared with the original steel ladle (comparison ladle), the application effect is analyzed. Due to the stable heat storage of the ladle wall after refining, the validity of the models are verified in ladle furnace (LF) process. The results show that the new calculation method is feasible, and the relevant parameter settings in the FEM and Boltzmann mathematical model are correct. Finally, after using the new aerogel insulation material, the temperature of molten steel is reduced by 16.67 °C, and the production cost is reduced by CNY 5.15/ton of steel.
      Citation: Coatings
      PubDate: 2021-10-01
      DOI: 10.3390/coatings11101205
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1206: Plasma Enhanced Atomic Layer Deposition of
           Tantalum (V) Oxide

    • Authors: Pavel Fedorov, Denis Nazarov, Oleg Medvedev, Yury Koshtyal, Aleksander Rumyantsev, Vladimir Tolmachev, Anatoly Popovich, Maxim Yu Maximov
      First page: 1206
      Abstract: The tantalum oxide thin films are promising materials for various applications: as coatings in optical devices, as dielectric layers for micro and nanoelectronics, and for thin-films solid-state lithium-ion batteries (SSLIBs). This article is dedicated to the Ta-O thin-film system synthesis by the atomic layer deposition (ALD) which allows to deposit high quality films and coatings with excellent uniformity and conformality. Tantalum (V) ethoxide (Ta(OEt)5) and remote oxygen plasma were used as tantalum-containing reagent and oxidizing co-reagent, respectively. The influence of deposition parameters (reactor and evaporator temperature, pulse and purge times) on the growth rate were studied. The thickness of the films were measured by spectroscopic ellipsometry, scanning electron microscopy and X-ray reflectometry. The temperature range of the ALD window was 250–300 °C, the growth per cycle was about 0.05 nm/cycle. Different morphology of films deposited on silicon and stainless steel was found. According to the X-ray diffraction data, the as-prepared films were amorphous. But the heat treatment study shows crystallization at 800 °C with the formation of the polycrystalline Ta2O5 phase with a rhombic structural type (Pmm2). The results of the X-ray reflectometry show the Ta-O films’ density is 7.98 g/cm3, which is close to the density of crystalline Ta2O5 of the rhombic structure (8.18 g/cm3). The obtained thin films have a low roughness and high uniformity. The chemical composition of the surface and bulk of Ta-O coatings was studied by X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy. Surface of the films contain Ta2O5 and some carbon contamination, but the bulk of the films does not contain carbon and any precursor residues. Cyclic voltammetry (CVA) showed that there is no current increase for tantalum (V) oxide in a potential window of 3–4.2 V and has prospects of use as protective coatings for cathode materials of SSLIBs.
      Citation: Coatings
      PubDate: 2021-10-01
      DOI: 10.3390/coatings11101206
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1207: Wear Behavior of Borided Cold-Rolled High
           Manganese Steel

    • Authors: Fatih Hayat, Cihangir Tevfik Sezgin
      First page: 1207
      Abstract: In this study, a novel high-manganese steel (HMS) was borided at 850, 900 and 950 °C for 2, 4, and 6 h by the pack boriding process. Contrary to previous literature, borided HMS uncommonly exhibited saw-tooth morphology like low alloy steels, and manganese enhanced the boron diffusion. Another striking analysis is that the “egg-shell effect” did not occur. The present study demonstrated the silicon-rich zone for the first time in the literature by EDX mapping. Moreover, the formation mechanism of silicon-rich zones was explained and termed as “compact transfer of silicones (CTS)”. XRD analysis showed the existence of FeB, Fe2B, MnB and SiC phases. The boriding time and temperature increased the thickness of the boride layer from 31.41 μm to 117.65 µm. The hardness of the borided layer ranged from 1120 to 1915 HV0.05. The activation energy of borided HMS was found to be a very low result compared to high alloy steel investigated in the literature. The Daimler-Benz Rockwell-C adhesion test showed that adhesions of borided HMS surfaces are sufficient. The dry sliding wear tests showed that boriding treatment increased the wear resistance of untreated HMS by 5 times. The present study revealed that the boriding process extended the service life of HMS components.
      Citation: Coatings
      PubDate: 2021-10-01
      DOI: 10.3390/coatings11101207
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1208: Synthesis of Gd2Zr2O7 Coatings Using the
           Novel Reactive PS-PVD Process

    • Authors: Pawel Pędrak, Kamil Dychtoń, Marcin Drajewicz, Marek Góral
      First page: 1208
      Abstract: Ceramic topcoats of thermal barrier coatings (TBCs) make it possible to increase the working temperature of the hot sections of jet engines. Yttria-stabilized zirconia oxide (YSZ) is usually used to protect the turbine blades and vanes against high temperature and oxidation. It is necessary to develop new materials which can operate at higher temperatures in a highly oxidizing gas atmosphere. Re2Zr2O7-type pyrochlores are promising YSZ replacements. Usually, they are produced by mixing pure oxides in the calcination process at higher temperatures. In a recent article, the new concept of pyrochlore synthesis during the deposition process was presented. The new technology, called reactive plasma spray physical vapor deposition (reactive PS-PVD), was developed and a Gd2Zr2O7 (GZO) coating was achieved. The reactive PS-PVD process allowed for the use of a mixture of untreated ZrO2 and Gd2O3 powders as reactants, instead of the commercially available gadolinium zirconate powders used in other types of processes. The results of microstructure observations revealed a columnar microstructure in the produced ceramic layer. The phase composition indicated the presence of gadolinium zirconate. Thermal analysis showed a decrease in the thermal conductivity in the range of 700 to 1200 °C of the produced layers, as compared to the layer made of the currently used conventional YSZ.
      Citation: Coatings
      PubDate: 2021-10-01
      DOI: 10.3390/coatings11101208
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1209: The Study of the Influence of Matrix, Size,
           Rotation Angle, and Magnetic Field on the Isothermal Entropy, and the
           Néel Phase Transition Temperature of Fe2O3 Nanocomposite Thin Films by
           the Monte-Carlo Simulation Method

    • Authors: Dung Nguyen Trong, Van Cao Long, Ştefan Ţălu
      First page: 1209
      Abstract: In this paper, the study of the influence of the matrix structure (mxm) of thin-film, rotation angle (α), magnetic field (B), and size (D) of Fe2O3 nanoparticle on the magnetic characteristic quantities such as the magnetization oriented z-direction (MzE), z-axis magnetization (Mz), total magnetization (Mtot), and total entropy (Stot) of Fe2O3 nanocomposites by Monte-Carlo (MC) simulation method are studied. The applied MC Metropolis code achieves stability very quickly, so that after 30 Monte Carlo steps (MCs), the change of obtained results is negligible, but for certainty, 84 MCs have been performed. The obtained results show that when the mxm and α increase, the magnetic phase transition appears with a very small increase in temperature Néel (TNtot). When B and D increase, TNtot increases very strongly. The results also show that in Fe2O3 thin films, TNtot is always smaller than with Fe2O3 nano and Fe2O3 bulk. When the nanoparticle size is increased to nearly 12 nm, then TNtot = T = 300 K, and between TNtot and D, there is a linear relationship: TNtot = −440.6 + 83D. This is a very useful result that can be applied in magnetic devices and in biomedical applications.
      Citation: Coatings
      PubDate: 2021-10-02
      DOI: 10.3390/coatings11101209
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1210: Polyphenol-Rich Purified Bioactive Fraction
           Isolated from Terminalia catappa L.: UHPLC-MS/MS-Based Metabolite
           Identification and Evaluation of Their Antimicrobial Potential

    • Authors: Tumakuru Nataraj Sowmya, Koteshwar Anandrao Raveesha
      First page: 1210
      Abstract: Background: Antimicrobial resistance is a major threat to humankind and the advancement of resistance due to genetic modifications and other defense mechanisms that make the current antibiotics ineffective or less efficacious. Objective: This investigation aims to isolate bioactive compounds from the leaf acetone extract of Terminalia catappa and to evaluate their antimicrobial potential against human pathogenic organisms. Materials and Methods: The bioactive extract was subjected to column chromatography. The fractions were assessed for their minimum inhibitory concentration, minimum fungicidal concentration, and time kill assays. UHPLC-MS/MS analysis was used to identify the bioactive molecules in the fraction. Results: The isolated fraction exhibited antimicrobial activity, with the most sensitive being Staphylococcus aureus (clinical isolate) and Methicillin Resistant Staphylococcus aureus 1503 (0.097 mg/mL), and the fungi Trichophyton rubrum and Candida albicans were inhibited at 0.097 mg/mL. The time kill assay exhibited bactericidal properties towards S. aureus (clinical isolate) and Salmonella typhi (MTCC 733). Additionally, MRSA 1503 and Proteus vulgaris exhibited bacteriostatic activities. The UHPLC-MS/MS analysis revealed that the fraction was rich in polyphenols. Alkaloids and some ellagitannins were identified for the first time. Conclusion: The results highlight the significant inhibition of multidrug-resistant MRSA strains and fungi by the polyphenol-rich fraction. The investigation reveals the potential use of the identified compounds for antimicrobial use, which could lower the implication of multidrug resistance.
      Citation: Coatings
      PubDate: 2021-10-02
      DOI: 10.3390/coatings11101210
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1211: Application of Vegetal Oils in Developing
           Bioactive Paper-Based Materials for Food Packaging

    • Authors: Anamaria Irimia, Elena Stoleru, Cornelia Vasile, Adrian Bele, Mihai Brebu
      First page: 1211
      Abstract: A major disadvantage of conventional food packaging materials is the difficulty in disposal and recycling, due to their high stability to environmental and thermal stress. The trend now is to develop new eco-friendly food packaging that can substitute fossil fuel derived materials. Cellulose, the main constituent of paper-based food packages, is a favorable starting material for such purpose. In this study we present a new method to obtain bioactive paper based materials suitable for food packaging applications. By combining eco-friendly activation processes (cold plasma or gamma irradiation) and bioactive plant oils (clove essential oil and rosehip seeds vegetal oil) for modification of kraft paper, new materials with antioxidant and antibacterial activity were obtained. The oil-loaded bioactive paper based materials presented increased hydrophobicity (from 97° in the case of kraft paper to 115° for oil-loaded sample) and decreased water adsorption (a one-quarter decrease). Due to differential interactions with the functional groups of plant oils, the modified kraft paper presents different antibacterial and antioxidant properties. Essential clove oil imprinted higher antioxidant activity (owing to the high content in eugenol and eugenol acetate phenolic compounds and were more efficient in reducing the bacterial growth on fresh beef meat and especially on fresh curd cheese. The cold pressed rosehip seeds oil acted as aslightly better antibacterial agent against Listeria monocytogenes (+), Salmonella enteritidis (-) and Escherichia coli (-) bacterial strains. Thus, the newly developed bioactive paper could be used as effective packaging material that can help preserving food quality for longer time.
      Citation: Coatings
      PubDate: 2021-10-02
      DOI: 10.3390/coatings11101211
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1212: Design of an Active Edible Coating Based on
           Sodium Caseinate, Chitosan and Oregano Essential Oil Reinforced with
           Silica Particles and Its Application on Panela Cheese

    • Authors: Luis Fernando Ríos-de-Benito, Monserrat Escamilla-García, Blanca García-Almendárez, Aldo Amaro-Reyes, Prospero Di Pierro, Carlos Regalado-González
      First page: 1212
      Abstract: Active edible films and coatings incorporating antimicrobial agents such as essential oils are studied to improve the shelf-life of fresh foods. The aim of this work was to study a mixture of sodium caseinate-chitosan (SC:CH), added with mesoporous silica nanoparticles filled with oregano essential oil (MSN-OEO), to produce an active edible coating for Panela cheese and to evaluate its properties during refrigerated storage for 15 days. The OEO was extracted by hydrodistillation and was incorporated into the MSN. Films based on SC:CH of 4:1 and 8:1 ratios with and without MSN-OEO were produced and the mechanical, barrier, physicochemical and microbiological properties of the films were evaluated. The SC:CH 8:1 ratio (w/w) with MSN-OEO showed reduced mean particle size (764.8 ± 23.3 nm), and a stable solution (zeta potential = 29.9 ± 1.1 mV). The thickness and solubility were influenced by the incorporation of MSN-OEO making it thinner and less soluble. Panela cheese samples were coated by the spray method using the SC:CH 8:1 containing MSN-OEO film forming solution. The final pH of the control cheese was 0.5 units lower than that of the coated cheese, whereas final moisture loss of the control cheese was 4.2 times that of the coated cheese. The mesophilic aerobic bacteria and of molds and yeasts populations achieved a reduction of about 2 Log10 UFC/g after 15 days of storage. Due to microbial growth delay, and little moisture loss, this active coating may improve the quality and safety of Panela cheese.
      Citation: Coatings
      PubDate: 2021-10-02
      DOI: 10.3390/coatings11101212
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1213: Microstructure, Mechanical and
           Antibacterial Properties of TiNb-Based Alloy Implanted by Silver Ions

    • Authors: Tian Tian, Bo Dang, Fengkun Li, Kai Yang, Dongbo Wei, Pingze Zhang
      First page: 1213
      Abstract: In this study, in order to obtain an antibacterial property for the TiNb-based alloy, the metal vapor vacuum arc (MEVVA) ion implantation technology was applied to implant the silver on the surface of TiNb-based alloy, which brought the change of the microstructures and mechanical properties for the surface of substrate. It was found that the diffusely distributed silver nanoparticles generated on the outermost surface of the implanted layer and the Ag element exist as a solid-solution state in the implanted layer. Meanwhile, the region of the implanted layer mainly constituted nanocrystalline structures based on the analyses of microstructures. Hence, the nanocrystalline strengthening effect formed by high-energy ion bombardment and the solid solution strengthening effect of silver atoms made contributions to the increase of surface comprehensive mechanical properties, including the surface hardness and elastic modulus. Finally, the suitable Ag-implanted specimen can obtain excellent antibacterial ability. Except for the antibacterial mechanism of silver ions release, the dispersed silver nanoparticles on the surface also provide the contact antimicrobial mechanism, which is the Schottky barrier–dependent antimicrobial efficacy of silver nanoparticles.
      Citation: Coatings
      PubDate: 2021-10-02
      DOI: 10.3390/coatings11101213
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1214: Sintering Modeling of Thermal Barrier
           Coatings at Elevated Temperatures: A Review of Recent Advances

    • Authors: Jinrong Yan, Xin Wang, Kuiying Chen, Kang N. Lee
      First page: 1214
      Abstract: To achieve a higher efficiency in gas turbine engine by increasing the inlet-temperature of burning gas is one of the primary goals in aviation industry. The development of thermal barrier coating system (TBCs) continuously raises the inlet-temperature of gas turbine engine in the past decades. Due to the complexity of TBCs and harsh operation environments, the degradation and failure mechanisms of hot section components have not been fully understood, and consequently limits the application of TBCs. It was identified that high-temperature sintering of the topcoat in a typical TBC could be one of the major sources of its failure since the microstructures of the constituent coating layers evolve dynamically during the service period, resulting in significant changes of mechanical and thermal physical properties of the coating system. This paper intends to review recent advances of analytical and numerical modeling of sintering of topcoat in TBCs including the modeling methodology and applications of the models, particularly the implementation of finite element combined with specific materials constitutive functions. Critical remarks on the future development and applications of these models are also discussed in the end.
      Citation: Coatings
      PubDate: 2021-10-03
      DOI: 10.3390/coatings11101214
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1215: Biogenesis of Silver Nanoparticles and Its
           Multifunctional Anti-Corrosion and Anticancer Studies

    • Authors: Leena V. Hublikar, Sharanabasava V. Ganachari, Narasimha Raghavendra, Nagaraj R. Banapurmath, Veerabhadragouda B. Patil, T. M. Yunus Khan, Irfan Anjum Badruddin
      First page: 1215
      Abstract: In the present research, silver nanoparticles were synthesized using ground nutshell and characterized using UV-visible, FTIR and PXRD. The SEM and HR-TEM aided in confirming the nano size, surface morphology and phase purity of the AgNPs. The quantum chemical, electrochemical, and structural studies were carried out to understand electrochemical properties. In addition, biological study such as anti-cancerous activity was carried out, and IC-50 values 80.25 µg/mL for A549 lung cancer cell lines. The effective electrochemical anti-corrosion activities were also studied. The majority constituents of ground nutshell are flavonoids, in a small quantity of alkaloids and phenolic acids, which provide more stability to synthesize silver nanoparticles and avoid agglomeration. These functional moieties enhance the unique properties in the field, as in drug delivery systems, magnetic applications, and metallic, semi-conducting core-shell nanoparticles.
      Citation: Coatings
      PubDate: 2021-10-04
      DOI: 10.3390/coatings11101215
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1216: Antimicrobial Peptides-Coated Stainless
           Steel for Fighting Biofilms Formation for Food and Medical Fields: Review
           of Literature

    • Authors: Mayssane Hage, Hikmat Akoum, Nour-Eddine Chihib, Charafeddine Jama
      First page: 1216
      Abstract: Emerging technology regarding antimicrobial coatings contributes to fighting the challenge of pathogenic bacterial biofilms in medical and agri-food environments. Stainless steel is a material widely used in those fields since it has satisfying mechanical properties, but it, unfortunately, lacks the required bio-functionality, rendering it vulnerable to bacterial adhesion and biofilm formation. Therefore, this review aims to present the coatings developed by employing biocides grafted on stainless steel. It also highlights antimicrobial peptides (AMPs)used to coat stainless steel, particularly nisin, which is commonly accepted as a safe alternative to prevent pathogenic biofilm development.
      Citation: Coatings
      PubDate: 2021-10-04
      DOI: 10.3390/coatings11101216
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1217: Vapour Phase Deposition of Thin Siloxane
           Coatings on the Iron Surface. The Impact of the Layer Structure and Oxygen
           Adsorption on Corrosion Stability

    • Authors: Andrei Nazarov, Maxim Petrunin, Liudmila Maksaeva, Tatyana Yurasova, Pierluigi Traverso, Andrey Marshakov
      First page: 1217
      Abstract: The mechanism of iron corrosion protection by thin siloxane films was clarified. Quartz crystal microbalance technique (QCM) was applied to control the vapour phase deposition of alkoxysilanes and the formation of thin siloxane films. It was shown that the addition of water vapour increased the thickness of the grafted siloxane films. Crystal-like films spontaneously grow to 10–16 monolayers at 100% RH of Ar flow due to the catalytic effect of the surface. X-ray photoelectron (XPS) and Auger spectroscopies analysed the thin siloxane films and Scanning Kelvin Probe (SKP) showed the formation of iron-siloxane bonds passivating the iron surface. The films showed high hydrophobicity and corrosion inhibition in humid air contaminated by sulphur dioxide. Thick films were less ordered, hydrophilic and accelerated the corrosion of iron. For corrosion protection, the presence of oxygen in the atmosphere is extremely important. In a wet Ar atmosphere, contaminated by sulphur dioxide, the surfaces are not stable and quickly corroded. Oxygen adsorption stabilizes the surface oxide film that correspondingly preserves the anchoring iron-siloxane bonds and enables corrosion protection by the coating.
      Citation: Coatings
      PubDate: 2021-10-04
      DOI: 10.3390/coatings11101217
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1218: Distribution of the Deposition Rates in an
           Industrial-Size PECVD Reactor Using HMDSO Precursor

    • Authors: Žiga Gosar, Denis Đonlagić, Simon Pevec, Bojan Gergič, Miran Mozetič, Gregor Primc, Alenka Vesel, Rok Zaplotnik
      First page: 1218
      Abstract: The deposition rates of protective coatings resembling polydimethylsiloxane (PDMS) were measured with numerous sensors placed at different positions on the walls of a plasma-enhanced chemical vapor deposition (PECVD) reactor with a volume of approximately 5 m3. The plasma was maintained by an asymmetric capacitively coupled radiofrequency (RF) discharge using a generator with a frequency 40 kHz and an adjustable power of up to 8 kW. Hexamethyldisiloxane (HMDSO) was leaked into the reactor at 130 sccm with continuous pumping using roots pumps with a nominal pumping speed of 8800 m3 h−1 backed by rotary pumps with a nominal pumping speed of 1260 m3 h−1. Deposition rates were measured versus the discharge power in an empty reactor and a reactor loaded with samples. The highest deposition rate of approximately 15 nm min–1 was observed in an empty reactor close to the powered electrodes and the lowest of approximately 1 nm min–1 was observed close to the precursor inlet. The deposition rate was about an order of magnitude lower if the reactor was fully loaded with the samples, and the ratio between deposition rates in an empty reactor and loaded reactor was the largest far from the powered electrodes. The results were explained by the loss of plasma radicals on the surfaces of the materials facing the plasma and by the peculiarities of the gas-phase reactions typical for asymmetric RF discharges.
      Citation: Coatings
      PubDate: 2021-10-05
      DOI: 10.3390/coatings11101218
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1219: Laser Fusion of Aluminum Powder Coated with
           Diamond Particles via Selective Laser Melting: Powder Preparation and
           Synthesis Description

    • Authors: Alexander S. Shinkaryov, Dmitriy Yu. Ozherelkov, Ivan A. Pelevin, Sergey A. Eremin, Vyacheslav N. Anikin, Maxim A. Burmistrov, Stanislav V. Chernyshikhin, Alexander A. Gromov, Anton Yu. Nalivaiko
      First page: 1219
      Abstract: This work aims to study the possibility of obtaining Al–C composite from AlSi10MgCu aluminum matrix with the addition of 500 nm-sized diamond particles by selective laser melting (SLM) process. Al–C composite powder was prepared by mechanical mixing to form a uniform cover along the surface of aluminum particles. The diamond content in the resulting AlSi10MgCu-diamond composite powder was equal to 0.67 wt %. The selection of the optimal SLM parameters for the obtained composite material is presented. For materials characterization, the following methods were used: scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy. X-ray photoelectron spectroscopy (XPS) was applied after SLM printing for a detailed investigation of the obtained composites. The presence of carbon additives and the formation of aluminum carbides in the material after the SLM process were demonstrated.
      Citation: Coatings
      PubDate: 2021-10-05
      DOI: 10.3390/coatings11101219
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1220: Comparative Study of High-Temperature
           Annealed and RTA Process β-Ga2O3 Thin Film by Sol–Gel Process

    • Authors: Min-Sung Bae, Seoung-Hyoun Kim, Jin-Su Baek, Jung-Hyuk Koh
      First page: 1220
      Abstract: As a wide energy band gap semiconductor, a Ga2O3 thin film was prepared by the sol–gel process with different annealing processes. Since Ga2O3 is a type of metal oxide structure, an oxygen annealing process can be considered to remove oxygen defects. An effective oxygen annealing process can help form a β-Ga2O3 structure with reduced defects. In this study, different types of annealing effects for β-Ga2O3 were investigated and compared. An electric furnace process using thermal effect characteristics of and an Rapid Thermal Annealing (RTA) process applied with an infrared radiation light source were compared. Two and 4 h thermal annealing processes were conducted at 900 °C in the furnace. Meanwhile, to study the optical annealing effects, 2 h furnace at 900 °C + 15 min in rapid thermal annealing and only 15 min in rapid thermal annealing effects were compared, respectively. Through increasing the thermal annealing temperature and time, β-Ga2O3 can be formed even though a sol–gel process was employed in this experiment. An annealing temperature of at least 900 °C was required to form β-Ga2O3 thin film. Moreover, by introducing an RTA process just after the spinning process of thin film, a β-Ga2O3 thin film was formed on the sapphire substrates. Compared with the electric furnace process applied for 2 h, the RTA process performed in 15 min has a relatively short process time and results in similar structural and optical characteristics of a thin film. From the X-ray diffraction patterns and UV spectrometer analysis, optically annealed β-Ga2O3 thin films on the sapphire substrate showed a highly crystalized structure with a wide energy band gap of 4.8 eV.
      Citation: Coatings
      PubDate: 2021-10-05
      DOI: 10.3390/coatings11101220
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1221: Machine Learning Prediction of Electron
           Density and Temperature from Optical Emission Spectroscopy in Nitrogen
           Plasma

    • Authors: Jun-Hyoung Park, Ji-Ho Cho, Jung-Sik Yoon, Jung-Ho Song
      First page: 1221
      Abstract: We present a non-invasive approach for monitoring plasma parameters such as the electron temperature and density inside a radio-frequency (RF) plasma nitridation device using optical emission spectroscopy (OES) in conjunction with multivariate data analysis. Instead of relying on a theoretical model of the plasma emission to extract plasma parameters from the OES, an empirical correlation was established on the basis of simultaneous OES and other diagnostics. Additionally, we developed a machine learning (ML)-based virtual metrology model for real-time Te and ne monitoring in plasma nitridation processes using an in situ OES sensor. The results showed that the prediction accuracy of electron density was 97% and that of electron temperature was 90%. This method is especially useful in plasma processing because it provides in-situ and real-time analysis without disturbing the plasma or interfering with the process.
      Citation: Coatings
      PubDate: 2021-10-06
      DOI: 10.3390/coatings11101221
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1222: Development of
           Dithieno[3,2-b:2′,3′-d]thiophene (DTT) Derivatives as
           Solution-Processable Small Molecular Semiconductors for Organic Thin Film
           Transistors

    • Authors: Eunjin Choi, Yuhyeon Jang, Dongil Ho, Wookil Chae, Taeshik Earmme, Choongik Kim, SungYong Seo
      First page: 1222
      Abstract: Novel solution-processable dithieno[3,2-d:2′,3′-d]thiophene (DTT) derivatives with alkylated thiophene or alkyl chain substituents, 2,6-bis(5-octylthiophen-2-yl)dithieno[3,2-b:2′,3′-d]thiophene (compound 1), 2,6-bis(5-(2-ethylhexyl)thiophen-2-yl)dithieno[3,2-b:2′,3′-d]thiophene (compound 2), and 2,6-dioctyldithieno[3,2-b:2′,3′-d]thiophene (compound 3), have been synthesized and employed as small molecular organic semiconductors for organic field-effect transistors (OFETs). All compounds exhibited good thermal stability over 290 °C, while different side groups of DTT compounds afforded different melting temperatures. The molecular orbital energy levels were experimentally and theoretically calculated, and their trend was almost the same. The developed compounds were employed as active layers for top-contact/bottom-gate OFETs with average charge carrier mobility as high as 0.10 cm2/Vs and current on/off ratio > 107 in ambient atmosphere. Notably, DTT derivative with linear alkyl chain (-octyl) substituents showed the best device performance. High device performance could be attributed to the large grains and continuous surface coverages as well as high film texture of the corresponding semiconductor films.
      Citation: Coatings
      PubDate: 2021-10-08
      DOI: 10.3390/coatings11101222
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1223: Hybrid Zinc-Based Multilayer Systems with
           Improved Protective Ability against Localized Corrosion Incorporating
           Polymer-Modified ZnO or CuO Particles

    • Authors: Nelly Boshkova, Kamelia Kamburova, Tsetska Radeva, Nikolai Boshkov
      First page: 1223
      Abstract: Localized corrosion and biofouling cause very serious problems in the marine industries, often related to financial losses and environmental accidents. Aiming to minimize the abovementioned, two types of hybrid Zn-based protective coatings have been composed. They consist of a very thin underlayer of polymer-modified ZnO or CuO nanoparticles and toplayer of galvanic zinc with a thickness of ~14 µm. In order to stabilize the suspensions of CuO or ZnO, respectively, a cationic polyelectrolyte polyethylenimine (PEI) is used. The polymer-modified nanoparticles are electrodeposited on the steel (cathode) surface at very low cathodic current density and following pH values: 1/CuO at pH 9.0, aiming to minimize the effect of aggregation in the suspension and dissolution of the CuO nanoparticles; 2/ZnO at pH 7.5 due to the dissolution of ZnO. Thereafter, ordinary zinc coating is electrodeposited on the CuO or ZnO coated low-carbon steel substrate from a zinc electrolyte at pH 4.5–5.0. The two-step approach described herein can be used for the preparation of hybrid coatings where preservation of particles functionality is required. The distribution of the nanoparticles on the steel surface and morphology of the hybrid coatings are studied by scanning electron microscopy. The thickness of the coatings is evaluated by a straight optical microscope and cross-sections. The protective properties of both systems are investigated in a model corrosive medium of 5% NaCl solution by application of potentiodynamic polarization (PDP) curves, open circuit potential (OCP), cyclic voltammetry (CVA), and polarization resistance (Rp) measurements. The results obtained allow us to conclude that both hybrid coatings with embedded polymer-modified CuO or ZnO nanoparticles ensure enhanced corrosion resistance and protective ability compared to the ordinary zinc.
      Citation: Coatings
      PubDate: 2021-10-08
      DOI: 10.3390/coatings11101223
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1224: Effect of Transformation Plasticity on Gear
           Distortion and Residual Stresses in Carburizing Quenching Simulation

    • Authors: Xusheng Li, Dongying Ju, Jianting Cao, Sirui Wang, Yong Chen, Fangbo He, Hui Li
      First page: 1224
      Abstract: This paper addresses the effect of gear steel on distortion and residual stresses due to phase transformation in carburizing and quenching. In particular, the martensitic and bainitic phase transformation expansion and transformation plasticity properties of two automotive gearbox steels (20CrMnTiH and 20MnCr5) and their physical parameters are measured by experiments of transformation plasticity properties. Numerical simulations of the actual carburizing and quenching process of the gearbox spline helical gears were carried out in combination with the thermal and mechanical properties with temperature variations calculated by the material design software JMAT-Pro. In particular, the phase transformation properties of the two materials and their influence on the distortion and residual stresses after carburizing and quenching were verified by experiments of transformation plasticity and numerical simulations. A reliable basis is provided for predicting the distortion mechanism of gear steels in carburizing and quenching.
      Citation: Coatings
      PubDate: 2021-10-09
      DOI: 10.3390/coatings11101224
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1225: DLC-Based Coatings Obtained by
           Low-Frequency Plasma-Enhanced Chemical Vapor Deposition (LFPECVD) in
           Cyclohexane, Principle and Examples

    • Authors: Frederic Sanchette, Mohamed El Garah, Sofiane Achache, Frederic Schuster, Caroline Chouquet, Cédric Ducros, Alain Billard
      First page: 1225
      Abstract: The LFPECVD (Low-Frequency Plasma-Enhanced Chemical Vapor Deposition) technique is now used on an industrial scale for the deposition of carbon-based coatings for several applications. This short review recalled the main principles of LFPECVD and provided examples of DLC-based films. The main differences between low-frequency (LF) and radio-frequency (RF) discharges were also recalled here and examples of deposition and characterization of carbon-based films were proposed. The influence of the bias voltage or the temperature of the active electrode on the deposition rate and the structure of a-C: H films obtained in cyclohexane/hydrogen mixtures was first discussed. Next, the properties of carbon-based films doped with silicon were described and, finally, it was shown that multilayer architectures make it possible to reduce the stresses without altering their tribological properties.
      Citation: Coatings
      PubDate: 2021-10-09
      DOI: 10.3390/coatings11101225
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1226: Coating Characteristic of Hydroxyapatite on
           Titanium Substrates via Hydrothermal Treatment

    • Authors: Pham Trung Kien, Tran Ngo Quan, Le Huynh Tuyet Anh
      First page: 1226
      Abstract: Medical pure titanium (Ti) shows excellent chemical stability and mechanical properties in clinical uses, but its initial fixation with host bone, when implanted, is usually delayed owing to the bioinert Ti surface. In this study, we fabricate the hydroxyapatite (HA)-coated titanium by three steps reactions: (1) to form an activated O2− layer by immersing Ti substrate into an alkaline solution such as NaOH; (2) the O2− bonds with Ca2+ to form Ca–O–Ti bonding, in which O plays the part of bridge materials between Ca and Ti substrate and (3) the conversion of Ca–O–Ti samples to HA-coated Ti samples by immersion into Na2HPO4 2 M at 180 °C for 48 h using hydrothermal methods. The effect of different phosphate solutions (NaH2PO4 2 M and Na2HPO4 2 M solution) and hydrothermal treatment time (24 and 48 h) on the characteristic of hydroxyapatite coating titanium substrate is also investigated using the optical microscope, thin film XRD and SEM/EDX. The HA-coated Ti samples fabricated by immersion into Na2HPO4 2 M at 180 °C for 48 h show fiber HA covering Titan substrate with a diameter varying from 0.1 to 0.3 µm. These HA-coated Ti samples can be regarded as promising multifunctional biomaterials.
      Citation: Coatings
      PubDate: 2021-10-09
      DOI: 10.3390/coatings11101226
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1227: Framework for Mitigation of Welding Induced
           Distortion Through Response Surface Method and Reinforcement Learning

    • Authors: Waheed, Saeed, Butt, Anjum
      First page: 1227
      Abstract: Welding induced distortion causes dimensional inaccuracies in parts being produced and assembly fit-up problems during manufacturing. In this study, a framework is proposed to mitigate weld distortion at the design stage. A sequential approach is adopted to optimize the welding process. In the first phase, welding process parameters are optimized through the response surface method. The effect of these parameters on the overall distortion of the welded part is observed by a simulation of the welding process. In the second phase, the weld sequence is optimized using the optimum weld parameters. A reinforcement learning-based Q-learning technique is used to select the optimum welding path by sequential observation of weld distortion at each segment being welded. The optimum process parameters and weld path sequence have been selected for 3 mm steel plates having a lap joint configuration and a 2 mm vent panel with a butt joint configuration. It is concluded that the combination of the optimum welding parameters and welding sequence yields minimum distortion. By applying this framework, a reduction of 19% is observed in overall welding induced distortion.
      Citation: Coatings
      PubDate: 2021-10-09
      DOI: 10.3390/coatings11101227
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1228: Study on the Structural Characteristics of
           Bird Necks and Their Static Motion Features in the Sagittal Plane

    • Authors: Jiajia Wang, Wenfeng Jia, Fu Zhang, Xiqiang Ma, Zhaomei Qiu, Zhihui Qian, Luquan Ren, Zhijun Guo, Yakun Zhang
      First page: 1228
      Abstract: The necks of birds that possess complex structures, graceful curves, and flexible movements are perfect natural motion actuators. Studying their structural features, mechanic characteristics, and motion rules can provide valuable references for imitating such actuators and motion functions artificially. Previous studies have analyzed the influence of two-dimensional motion geometric features and anatomical structure of the neck on motion efficiency and motion stability. However, the mechanism of motion flexibility from the perspective of neck structure has not been investigated. This study investigates the general law of the relationship between the structural parameters and motion characteristics of birds’ necks using tomography technology and 3D reconstruction technology. The results show that the structural characteristics of geese and ducks are similar, and there are significant differences in joint motion characteristics. Geese obtains complex neck postures through active intervertebral joints and highly flexible facet joints and possesses higher neck flexibility than ducks. This study provides a generic measuring method for obtaining birds’ cervical spinal vertebral structural dimensional parameters and offers a new theoretical concept for bionic robotic structural design and manufacture.
      Citation: Coatings
      PubDate: 2021-10-09
      DOI: 10.3390/coatings11101228
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1229: Influence of Voltage Sags on the Continuity
           of the Operation and Lifespan of Single-Phase Industrial Robots

    • Authors: Grzegorz Putynkowski, Krzysztof Woźny, Elzbieta Szychta, Leszek Szychta
      First page: 1229
      Abstract: Due to the increase in the number of automated processes that employ industrial robots (especially in industrial and laboratory environments, including vacuum systems), and the resulting increase in the number of unresolved service requests, the purpose of the authors’ research was to confirm the occurrence of disturbances in the form of voltage sags that are not recorded by automation systems and which lead to the destruction of robots or their equipment in areas defined by the characteristics of ITIC/SEMI F47 and CBEMA as being free from such disturbances. The article also describes the environmental classification of robots by their process functionalities/features, and recommends equipment that is able to compensate for these disturbances. Such a classification approach can be an excellent tool for building an exploitation culture and assist the conscious selection of electrical equipment in robotised systems susceptible to disturbances (e.g., robots in load-lock in vacuum environment).
      Citation: Coatings
      PubDate: 2021-10-09
      DOI: 10.3390/coatings11101229
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1230: Effect of Modulation Periods on the
           Mechanical and Tribological Performance of MoS2–TiL/MoS2–TiH
           Multilayer Coatings

    • Authors: Ping Zhang, Puyou Ying, Changhong Lin, Tao Yang, Jianbo Wu, Min Huang, Tianle Wang, Yihang Fang, Vladimir Levchenko
      First page: 1230
      Abstract: MoS2–Ti coating is a widely used solid lubricant owing to its low friction coefficient. The mechanical and tribological performance of the coating can be further improved via introducing a multilayer structure, which is closely related to the modulation period and significantly affects the properties of the coating. Herein, the effect of two different modulation periods on the mechanical and tribological performance of the MoS2–TiL/MoS2–TiH multilayer coatings (where L and H represent low and high-powered sputtering of the titanium target) was studied. The performance of the coatings was found to depend on modulation periods of single layer thickness and thickness ratio, respectively. When the thickness ratio of MoS2–TiL layer to MoS2–TiH layer was fixed with different number of layers, the adverse effects of the interface outweighed the beneficial effect; thus, the mechanical and tribological performance of the multilayer coatings were improved with an increase in the single layer thickness. When the effect of the multilayer interfaces on the studied coatings was similar with the same number of layers, the MoS2–TiH layer had more impact on the hardness of the MoS2–TiL/MoS2–TiH multilayer coatings, whereas the MoS2–TiL layer substantially affected the adhesion properties, friction behavior and wear resistance. This study can provide a way to regulate coatings with different performance requirements via building different multilayer microstructures.
      Citation: Coatings
      PubDate: 2021-10-09
      DOI: 10.3390/coatings11101230
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1231: Performance and Fracture Analysis of
           Composite Interfaces for Semi-Flexible Pavement

    • Authors: Kuanghuai Wu, Xiaoyu Liu, Xu Cai, Wenke Huang, Jinlou Yu, Guihai Nie
      First page: 1231
      Abstract: Semi-flexible pavement is widely used in pavement engineering due to its excellent rutting resistance; however, it mainly fails due to cracking. Therefore, it is important to understand the properties of the aggregate–mortar–asphalt interfacial transition zone, to better understand the cracking mechanism of the semi-flexible pavement. In this work, we used pull-off tests and digital image analysis technology to compare and analyze the interfacial tensile strength and granite–bitumen–mortar interactions in three types of asphalt (70# matrix asphalt, PG76-22 modified asphalt and S-HV modified asphalt) at different curing ages. The analysis results showed that, for the three different bitumen materials, with settled mortar, the peak interfacial tensile strength values all occurred at approximately 14 d of curing. In addition, the order of the tensile strength followed the order of asphalt penetration degree; the order of the interfacial water damage resistance from weak to strong was 70# asphalt cementation specimen, PG76-22 modified asphalt cementation specimen, and S-HV modified asphalt cementation specimen. The results of this analysis highlight the original contributions of the optimum curing time for the composite interface of semi-flexible pavement materials prepared with different asphalts to reach optimum crack resistance.
      Citation: Coatings
      PubDate: 2021-10-09
      DOI: 10.3390/coatings11101231
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1232: The Difference of Marginal Bone
           Preservation between Dental Implants with Non-Threaded or Micro-Threaded
           Collar Designs

    • Authors: Mazen Almasri
      First page: 1232
      Abstract: This study analyzes the marginal bone loss (MBL) among dental implants characterized with non-threaded collar design (NT) when compared to the more classic micro-threaded collar design (MC) as such might reflect the future dentogengival esthetics, implant metal show, and mucositis. A total of 112 patients who received 311 implants have been included in the study and analyzed for their postoperative MBL using sequential periapical radiographs. The prevalence of postoperative peri-implant mucositis was recorded as well. The periapical radiographic comparison was performed between the immediate postoperative record and at the 24-month recall visit. Among the 311 implants, 124 (39.9%) had NT implants, and 187 (60.1%) had MC implants. Out of the 112 patients, 37 (44.6%) were females, and 10 (34.5%) were males included in the NT group. In contrast, 46 (55.4%) females and 19 (65.5%) males were in the MC group. The mean age among the two groups was 41.43 ± 15.900 and 46.68 ± 16.070, respectively. In contrast, the mean MBL among the groups were 0.544 ± 0.7129 and 0.061 ± 0.2648, respectively. The change in MBL was not positively correlated with gender (p-value = 0.154) or age (p-value = 0.115) in both groups. However, there was a significant difference (p-value = 0.001, X2 = 62.796, Df = 4) of MBL between the two implant systems themselves. The MBL was higher in people implanted with the NT system when compared to MC. Therefore, the MC implant system can be a better choice for marginal bone preservation, especially in restoring esthetically demanding areas in the mouth.
      Citation: Coatings
      PubDate: 2021-10-11
      DOI: 10.3390/coatings11101232
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1233: Engineering Nanostructured Antimony-Based
           Anode Materials for Sodium Ion Batteries

    • Authors: Wen Luo, Jingke Ren, Wencong Feng, Xingbao Chen, Yinuo Yan, Noura Zahir
      First page: 1233
      Abstract: Sodium-ion batteries (SIBs) are considered a potential alternative to lithium-ion batteries (LIBs) for energy storage due to their low cost and the large abundance of sodium resources. The search for new anode materials for SIBs has become a vital approach to satisfying the ever-growing demands for better performance with higher energy/power densities, improved safety and a longer cycle life. Recently, antimony (Sb) has been extensively researched as a promising candidate due to its high specific capacity through an alloying/dealloying process. In this review article, we will focus on different categories of the emerging Sb based anode materials with distinct sodium storage mechanisms including Sb, two-dimensional antimonene and antimony chalcogenide (Sb2S3 and Sb2Se3). For each part, we emphasize that the novel construction of an advanced nanostructured anode with unique structures could effectively improve sodium storage properties. We also highlight that sodium storage capability can be enhanced through designing advanced nanocomposite materials containing Sb based materials and other carbonaceous modification or metal supports. Moreover, the recent advances in operando/in-situ investigation of its sodium storage mechanism are also summarized. By providing such a systematic probe, we aim to stress the significance of novel nanostructures and advanced compositing that would contribute to enhanced sodium storage performance, thus making Sb based materials as promising anodes for next-generation high-performance SIBs.
      Citation: Coatings
      PubDate: 2021-10-11
      DOI: 10.3390/coatings11101233
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1234: Effect of Coarse Recycled Aggregate on
           Failure Strength for Asphalt Mixture Using Experimental and DEM Method

    • Authors: Yongsheng Yao, Jue Li, Chenghao Liang, Xin Hu
      First page: 1234
      Abstract: Coarse aggregate is the major part of asphalt mixture, and plays an essential role in mechanical performance of pavement structure. However, the use of poor-quality coarse recycled aggregate (CRA) reduces the strength and stability of the aggregate skeleton. It is a challenge to predict accurately the influence of CRA on the performance of asphalt mixture. In this study, both a uniaxial compression test and a direct tensile test were carried out to evaluate the failure strength of asphalt concrete with four CRA content. The discrete element method (DEM) was applied to simulate the specimen of asphalt concrete considering the distribution and properties of CRA. The results showed that temperature and loading rate have a significant influence on failure strength, especially when the CRA content was more than 20%. With the increase of CRA content, both cohesion force and internal friction angle were gradually weakened. The proposed model can be used to predict the failure strength of asphalt mixture, since both experimental and simulated results had a high consistency and repeatability. With the decrease of CRA strength, the nominal cohesion force of the specimen decreased, while the internal friction angle increased.
      Citation: Coatings
      PubDate: 2021-10-11
      DOI: 10.3390/coatings11101234
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1235: Metaheuristic Optimization of Laminated
           Composite Plates with Cut-Outs

    • Authors: Celal Cakiroglu, Kamrul Islam, Gebrail Bekdaş, Sanghun Kim, Zong Woo Geem
      First page: 1235
      Abstract: The stacking sequence optimization of laminated composite plates while maximizing the structural performance or minimizing the weight is a subject investigated extensively in the literature. Meanwhile, research on the optimization of laminates with cut-outs has been relatively limited. Cut-outs being an indispensable feature of structural components, this paper concentrates on the stacking sequence optimization of composite laminates in the presence of circular cut-outs. The buckling load of a laminate is used as a metric to quantify the structural performance. Here the laminates are modeled as carbon fiber-reinforced composites using the finite element analysis software, ABAQUS. For the optimization, the widely used harmony search algorithm is applied. In terms of design variables, ply thickness, and fiber orientation angles of the plies are used as continuously changing variables. In addition to the stacking sequence, another geometric variable to consider is the aspect ratio (ratio of the length of the longer sides to the length of the shorter sides of the plate) of the rectangular laminates. The optimization is carried out for three different aspect ratios. It is shown that, by using dispersed stacking sequences instead of the commonly used 0°/±45°/±90° fiber angle stacks, significantly higher buckling loads can be achieved. Furthermore, changing the cut-out geometry is found to have a significant effect on the structural performance.
      Citation: Coatings
      PubDate: 2021-10-12
      DOI: 10.3390/coatings11101235
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1236: Analysis of Film Forming Law and
           Characteristics for an Air Static Spray with a Variable Position of the
           Plane

    • Authors: Yi Liu, Yong Zeng, Xueya Zhao, Jiuxuan Liu, Dezhi Liu
      First page: 1236
      Abstract: In order to accurately establish the film thickness distribution model of a static spraying plane with air gun displacement, the film forming law and characteristics of the static spraying plane with air gun displacement were analyzed. The spray simulation model was established by the Euler–Euler method, and the spray process and film forming condition were calculated. The numerical simulation results show that oblique spraying has a large influence on the near-surface liquid velocity. With the increase in the spray angle, the droplets at the edge of the torch diffuse to the inclined direction, and the uniformity of the coating distribution becomes worse. Spraying height has a large influence on droplet trajectory. The coating thickness decreased significantly with the increase in spraying height, and the coating diffused in the air increased. With the increase in spraying height, the more obvious the droplet diffusion at the edge of the torch, the worse the uniformity quality of the coating. In order to ensure better spraying quality, the spraying height and angle should be controlled within a reasonable range at the same time. Spraying experiments verified the film forming law and characteristics of static spraying with gun displacement.
      Citation: Coatings
      PubDate: 2021-10-12
      DOI: 10.3390/coatings11101236
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1237: Influence of Particle Concentration on the
           Elemental Penetration Region and Properties of Ni–P–SiC Composite
           Coatings Prepared through Sandblasting and Scanning Electrodeposition on
           45 Steel Surfaces

    • Authors: Zhengwei Zhang, Jieyu Xian, Hongbin Wu, Meifu Jin, Zhenyu Shen
      First page: 1237
      Abstract: Ni–P–SiC composite coating was prepared on 45 steel surfaces through sandblasting and scanning electrodeposition to explore the relationship between element penetration region and composite coating properties. The single-factor control variable method with particle concentration as the research variable was used. Results showed that with the gradually increasing concentration of SiC nanoparticles, a trend of first increasing and then gradually decreasing was observed for the surface and cross-sectional microstructure of the coating, interpenetration ability of the elements, adhesion performance, and corrosion resistance. The best deposition quality of the coating was obtained when the concentration of SiC nanoparticles was 3 g·L−1. For cross-sectional microstructure, the scratch test revealed that the maximum coating thickness was 17.3 μm, the maximum range of elemental penetration region was 28.39 μm, and the maximum adhesion of the composite coating was 36.5 N. The electrochemical test showed that the composite coating had a −0.30 V self-corrosion potential and 8.45 × 10−7 A·cm−2 self-corrosion current density, the slowest corrosion rate. In addition, the composite coating had the best corrosion resistance and the largest impedance arc radius corresponding to an equivalent impedance value R2 of 3108 Ω.
      Citation: Coatings
      PubDate: 2021-10-12
      DOI: 10.3390/coatings11101237
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1238: Influence of NaCl Freeze–Thaw Cycles on
           the Mechanical Strength of Reactive Powder Concrete with the Assembly Unit
           of Sulphoaluminate Cement and Ordinary Portland Cement

    • Authors: Zhangjie Cai, Hui Wang
      First page: 1238
      Abstract: The influence of sulphoaluminate cement and the dosage of polypropylene fibers on the basic mechanical strengths (compressive and flexural strengths) of reactive powder concrete (RPC) cured for 1 d, 3 d, 7 d, 14 d and 28 d is studied in this research. The content of sulphoaluminate cement ranges from 0% to 100% and the dosages of polypropylene fibers are 0%~3.5%, respectively. Moreover, the mechanical properties (compressive and flexural strengths), the relative dynamic elastic modulus (RDEM) and the chloride permeability of specimens with 50% sulphoaluminate cement and different dosages of polypropylene fibers are determined after the specimens are exposed to different NaCl freeze–thaw cycles. The water–binder ratio in this study is 0.25, and the sand-to-binder ratio is 1.25. Results show that the relationship between the mechanical strengths of RPC at early curing ages (lower than 7 d) and the sulphoaluminate cement content is a linear function with a positive correlation. However, when the curing age reaches 14 d, the compressive and flexural strengths decrease in the form of a linear function with the addition of sulphoaluminate cement. The correlation between the mechanical strengths and polypropylene fiber volume is a positive quadratic function. However, the mass loss rate and flexural strength loss rate increased in the form of a quadratic function, and RDEM shows a negative quadratic function with the freeze–thaw cycles. Moreover, the compressive strength loss rate increases linearly with the freeze–thaw cycle. The addition of polypropylene fibers can effectively improve the freeze–thaw resistance of cement mortar with an assembly unit of ordinary cement and sulphoaluminate cement.
      Citation: Coatings
      PubDate: 2021-10-12
      DOI: 10.3390/coatings11101238
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1239: Preparation of Degradable Superhydrophobic
           Mg/P/Z/F/H Composite Materials and Their Anticorrosion

    • Authors: Zhongxian Xi, Chengqing Yuan, Xiuqin Bai, Chun Wang, Anne Neville
      First page: 1239
      Abstract: In this study, the degradable superhydrophobic Mg/P/Z/F/H (magnesium/poly(-caprolactone)/zinc oxide/1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES)/heating process) composite materials were prepared through dip-coating method and heating process, for enhancing the corrosion resistance of the AZ91D magnesium alloys. The electrochemical measurements revealed that the Mg/P/Z/F/H materials significantly improved the corrosion resistance of the magnesium alloys in 3.5 wt.% NaCl. The Mg/P/Z/F/H composite materials exhibited efficient self-cleaning properties, good adhesion strength, and stability in wet atmosphere.
      Citation: Coatings
      PubDate: 2021-10-12
      DOI: 10.3390/coatings11101239
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1240: Additive Manufacturing of Tungsten Carbide
           Surfaces with Extreme Wear Resistivity

    • Authors: Florian Köhn, Michael Sedlmajer, Joachim Albrecht, Markus Merkel
      First page: 1240
      Abstract: Steel surfaces have been coated with Co-based tungsten carbide (WC) in an additive printing process. This process leads to compact and extremely mechanically stable surfaces. We performed tribological measurements using WC counter bodies under dry conditions and severe mechanical load. Low coefficients of friction, even for rough surfaces, were found and the resulting wear rates were extraordinarily small, even when compared to high-quality PVD film with a similar composition. These findings suggest a wide field of application for this novel preparation process for wear-resistive surfaces.
      Citation: Coatings
      PubDate: 2021-10-13
      DOI: 10.3390/coatings11101240
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1241: Research on Laser Cladding Co-Based Alloy
           on the Surface of Vermicular Graphite Cast Iron

    • Authors: Fuzhen Sun, Keqian Cai, Xiaoxu Li, Ming Pang
      First page: 1241
      Abstract: To further improve the hardness of the laser cladding layer on the surface of the vermicular graphite cast iron, the structural parameters of the laser cladding Co-base were designed and optimized, and the properties of the clad layer were evaluated using optical microscopy (OM), scanning electron microscopy (SEM), energy spectroscopy (EDS), X-ray diffractometer (XRD), electrochemical workstation, and friction wear equipment. The results show that the average hardness of the molten layer of Ni and Co-based composite cladding layer is 504 HV0.5, which is 0.64 times that of the Co-based cladding layer due to the combined factors of Ni-Cr-Fe equivalent to the dilution of the Ni-based cladding layer to the Co-based cladding layer. Due to the potential difference of the Ni, Cr, and Co elements on the surface of the cladding layer, the self-corrosion potential of the Ni and Co-based composite cladding layer is 1.08 times that of the Co-based cladding layer, and the self-corrosion current density is 0.51 times. Laser cladding Co-based cladding layer has high corrosion resistance. Under the influence of plastic deformation and oxidative wear of the cladding layer of the Ni and Co-based composite cladding layer, the wear amount of the cladding layer of the Ni and Co-based composite cladding layer is less.
      Citation: Coatings
      PubDate: 2021-10-13
      DOI: 10.3390/coatings11101241
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1242: Computational Modeling of Hybrid Sisko
           Nanofluid Flow over a Porous Radially Heated Shrinking/Stretching Disc

    • Authors: Umair Khan, Aurang Zaib, Anuar Ishak, Fahad S. Al-Mubaddel, Sakhinah Abu Bakar, Hammad Alotaibi, Hassan M. Aljohani
      First page: 1242
      Abstract: The present study reveals the behavior of shear-thickening and shear-thinning fluids in magnetohydrodynamic flow comprising the significant impact of a hybrid nanofluid over a porous radially shrinking/stretching disc. The features of physical properties of water-based Ag/TiO2 hybrid nanofluid are examined. The leading flow problem is formulated initially in the requisite form of PDEs (partial differential equations) and then altered into a system of dimensionless ODEs (ordinary differential equations) by employing suitable variables. The renovated dimensionless ODEs are numerically resolved using the package of boundary value problem of fourth-order (bvp4c) available in the MATLAB software. The non-uniqueness of the results for the various pertaining parameters is discussed. There is a significant enhancement in the rate of heat transfer, approximately 13.2%, when the impact of suction governs about 10% in the boundary layer. Therefore, the heat transport rate and the thermal conductivity are greater for the new type of hybrid nanofluid compared with ordinary fluid. The bifurcation of the solutions takes place in the problem only for the shrinking case. Moreover, the sketches show that the nanoparticle volume fractions and the magnetic field delay the separation of the boundarylayer.
      Citation: Coatings
      PubDate: 2021-10-13
      DOI: 10.3390/coatings11101242
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1243: Defective Microwave Photonic Crystals for
           Salinity Detection

    • Authors: Yuxia Zhu, Hongwei Yang
      First page: 1243
      Abstract: In this paper, defective microwave photonic crystals (MPCs) are designed to sense the salinity of aqueous solutions. The defective MPC sensors are constructed by two kinds of microwave dielectric layers and one defective salt solution layer. Transfer matrix method (TMM) for lossy medium is developed to calculate the transmittance spectra of the sensors. It is found that the peak transmittance of both the defective resonance within the microwave band gap (MBG) and transmitting modes outside the MBG monotonously decrease with the increase of salinity, while the resonant and transmitting mode frequencies remain unchanged. By comparing the four MPC sensor structures, the first transmitting mode in the upper frequency band outside the MBG of the 15-layer MPC sensor has the largest salinity sensing range from 0 to 40‰ with relative stable detecting sensitivity. The sensing principle is based on the fact that the dielectric loss factor of saline solution is much more sensitive to salinity than the dielectric constant in the microwave frequency band. The sensitivity, quality factor, and salinity detection range of the MPC sensors are calculated and compared. The reported defective MPC sensors are suitable to be used for non-contact salinity detection.
      Citation: Coatings
      PubDate: 2021-10-13
      DOI: 10.3390/coatings11101243
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1244: Effects of Specimen Size and Welded Joints
           

    • Authors: Pengfei Wang, Weiqiang Wang, Ming Zhang, Qiwen Zhou, Zengliang Gao
      First page: 1244
      Abstract: The effects of specimen size and welded joints on the very high cycle fatigue properties of compressor blade steel KMN-I were studied by ultrasonic fatigue testing. It was found that the S-N curve of large specimens had a slow decline above 107 cycles, and fatigue failure still occurred in the very high cycle regime (>107 cycles), while the very high cycle fatigue characteristics of welded specimens was less obvious, and the fatigue limit was observed. Metallographic observation and SEM analysis were carried out on the fracture of the specimens. The results showed that surface fractures were mostly observed in the large specimens, and only a small number of cracks initiated from non-metallic inclusions above 107 cycles. The cracks of welded specimens initiated from the surface below 107 cycles and initiated from the internal matrix above 107 cycles. In addition, the formation mechanism of GBF (granular bright facet) was analyzed by the “dispersive decohesion of spherical carbide” theory, and the fatigue strength and fatigue life were predicted, which was consistent with the experimental results.
      Citation: Coatings
      PubDate: 2021-10-13
      DOI: 10.3390/coatings11101244
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1245: Sol-Gel Coating Membranes for Optical Fiber
           Sensors for Concrete Structures Monitoring

    • Authors: Bárbara R. Gomes, Rui Araújo, Tatiana Sousa, Rita B. Figueira
      First page: 1245
      Abstract: The use of advanced sensing devices for concrete and reinforced concrete structures (RCS) is considered a rational approach for the assessment of repair options and scheduling of inspection and maintenance strategies. The immediate benefits are cost reduction and a reliable prevention of unpredictable events. The use of optical fiber sensors (OFS) for such purposes has increased considerably in the last few years due to their intrinsic advantages. In most of the OFS, the chemical transducer consists of immobilized chemical reagents placed in the sensing region of the optical sensor by direct deposition or by encapsulation in a polymeric matrix. The choice of the support matrix impacts directly on the performance of the OFS. In the last two decades, the development of OFS functionalized with organic–inorganic hybrid (OIH) sol–gel membranes have been reported. Sol–gel route is considered a simple method that offers several advantages when compared to traditional synthesis processes, allowing to obtain versatile materials with unique chemical and physical properties, and is particularly valuable in the design of OIH materials. This review will provide an update of the current state-of-the-art of the OFS based on OIH sol-gel materials for concrete and RCS since 2016 until mid-2021. The main achievements in the synthesis of OIH membranes for deposition on OFS will be discussed. The challenges and future directions in this field will also be considered, as well as the main limitations of OFS for RCS monitoring.
      Citation: Coatings
      PubDate: 2021-10-13
      DOI: 10.3390/coatings11101245
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1246: Tribological Behavior of NiTi Alloy
           Produced by Spark Plasma Sintering Method

    • Authors: Sneha Samal, Jana Cibulková, Radim Čtvrtlík, Jan Tomáštík, Lukáš Václavek, Jaromír Kopeček, Petr Šittner
      First page: 1246
      Abstract: The tribological behaviors of NiTi alloy produced by the spark plasma sintering (SPS) method before and after annealing were investigated at various loading conditions via indentation, scratch, and wear tests. Indentation tests were performed by a pyramidal Berkovich indenter, while scratch and wear tests were carried out by a diamond Rockwell spherical indenter at room temperature. The annealing of the as-prepared samples was performed at 350, 450, and 550 °C in the ambient atmosphere. The influence of the annealing temperature on the sample behavior towards tribological study was investigated here. The results indicated that the alloy annealed at 350 °C showed a higher hardness compared to the other annealed alloys. The scratch and wear resistance of the annealed sample at 350 °C showed a better performance in comparison to the other samples under a constant load. The high wear resistance of the annealed NiTi alloy may be attributed to its metastable R-phase. The detection and evaluation of acoustic emissions during the nano/micro-tribomechanical testing proved to be a very effective way for the exploration of the durability of SPS NiTi alloys.
      Citation: Coatings
      PubDate: 2021-10-14
      DOI: 10.3390/coatings11101246
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1247: Physicochemical Surface Treatment of Wood
           Raw Materials

    • Authors: Ruslan Rushanovich Safin, Ruslan Khasanshin, Shamil Ramilevich Mukhametzyanov, Albina Safina
      First page: 1247
      Abstract: Wood is a vital and widespread natural material [...]
      Citation: Coatings
      PubDate: 2021-10-14
      DOI: 10.3390/coatings11101247
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1248: Ce and Y Co-Doping Effects for
           (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 Lead-Free Ceramics

    • Authors: Chao Li, Jin-Su Baek, Jung-Hyuk Koh
      First page: 1248
      Abstract: CeO2 and Y2O3 were co-doped to (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 ceramics and sintered by conventional solid-state reaction process to form x wt.% CeO2-y wt.% Y2O3 doped (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 (CexYy-BCZT) ceramics. The effects of different contents of CeO2-Y2O3 dopants to the (Ba0.85Ca0.15) (Zr0.1Ti0.9)O3 composition were analyzed by studying the phase, surface microstructure, piezoelectric and ferroelectric properties of BCZT ceramics. In this study, we have shown that co-doping a small amount of CeO2 and Y2O3 will not change the phase structure of (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 ceramics. However, the proper introduction of CeO2 and Y2O3 can improve the piezoelectric constant and electromechanical coupling coefficient of BCZT ceramic samples. Moreover, these dopants can promote the grain growth process in (Ba0.85Ca0.15) (Zr0.1Ti0.9)O3 ceramics. C0.04Y0.02 doped (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 ceramic has the best piezoelectric properties compared with other composition, the results are as follows: Relative density = 96.9%, Kp = 0.583, and d33 = 678 pC/N, V = 8.9 V. It means that this Ce0.04Y0.02 doped (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 ceramic is a desired material in the application of lead-free ceramics.
      Citation: Coatings
      PubDate: 2021-10-14
      DOI: 10.3390/coatings11101248
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1249: Study of Slip Effects in Reverse Roll
           Coating Process Using Non-Isothermal Couple Stress Fluid

    • Authors: Hasan Shahzad, Xinhua Wang, Muhammad Bilal Hafeez, Zahir Shah, Ahmed Mohammed Alshehri
      First page: 1249
      Abstract: The non-isothermal couple stress fluid inside a reverse roll coating geometry is considered. The slip condition is considered at the surfaces of the rolls. To develop the flow equations, the mathematical modelling is performed using conservation of momentum, mass, and energy. The LAT (lubrication approximation theory) is employed to simplify the equations. The closed form solution for velocity, temperature, and pressure gradient is obtained. While the pressure and flow rate are obtained numerically. The impact of involved parameters on important physical quantities such as temperature, pressure, and pressure gradient are elaborated through graphs and in tabular form. The pressure and pressure gradient decreases for variation of the couple stress parameter and velocity ratio parameter K. While the variation of the slip parameter increases the pressure and pressure gradient inside the flow geometry. Additionally, flow rate decreases for the variation of the slip parameter as fluid starts moving rapidly along the roller surface. The most important physical quantity which is responsible for maintaining the quality of the coating and thickness is flow rate. For variation of both the couple stress parameter and the slip parameter, the flow rate decreases compared to the Newtonian case, consequently the coating thickness decreases for the variation of the discussed parameter.
      Citation: Coatings
      PubDate: 2021-10-14
      DOI: 10.3390/coatings11101249
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1250: Well Rehabilitation via the Ultrasonic
           Method and Evaluation of Its Effectiveness from the Pumping Test

    • Authors: Daniel Kahuda, Pavel Pech, Václav Ficaj, Hana Pechová
      First page: 1250
      Abstract: The exploitation of groundwater reserves, especially for drinking purposes, is becoming increasingly important. This fact has created the need to maintain wells in the best possible functional condition. However, wells are subject to an ageing process during intensive use, which entails an increase in up-to-date resistances in the well itself and its immediate surroundings (the skin zone). This causes a decrease in the efficiency of the well (a decrease in the pumped quantity, a decrease in the specific yield, an increase of the drawdown in the well, and creation of the skin zone). The increased hydraulic gradient in the skin zone causes an increase in the inflow rate to the well, thereby inducing the movement of fine material towards the casing. This material can clog the well casing and injection ports, which is compounded by an increase in chemical and biological plugging of the skin zone. In cooperation with the company sonic technologies, GmbH. (Sailauf, Germany), an experimental ultrasonic technology-based well rehabilitation assembly was developed and successfully tested. This article describes the prototype development of the ultrasonic device, including its incorporation into the rehabilitation set and a demonstration of its pilot deployment in the MO-4 pumping well in Czech Republic with an evaluation of the rehabilitation effects using the authors’ software (Dtest_ULTRA). Based on visual inspection and the results of hydraulic and geophysical analysis, the high efficiency of the tested technology was demonstrated in virtually all monitored parameters, where an improvement in the range of 25–55% compared to the original condition was identified.
      Citation: Coatings
      PubDate: 2021-10-14
      DOI: 10.3390/coatings11101250
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1251: Formation of Aligned α-Si3N4 Microfibers
           by Plasma Nitridation of Si (110) Substrate Coated with SiO2

    • Authors: Chang-Hua Yu, Kun-An Chiu, Thi-Hien Do, Li Chang, Wei-Chun Chen
      First page: 1251
      Abstract: Plasma nitridation of an amorphous SiO2 layer on Si (110) substrate can form well-aligned α-Si3N4 crystallites in fibrous morphology. Nitriding is performed at a temperature in the range of 800–1000 °C by using microwave plasma with a gas mixture of N2 and H2. Raman spectroscopy shows the characteristics of an α-Si3N4 phase without other crystalline nitrides. As shown by scanning electron microscopy, the formed α-Si3N4 microfibers on the Si substrate can be in a dense and straight array nearly along with Si <11¯0>, and can have a length over 2 mm with a diameter in the range of 5–10 μm. Structural characterization of scanning transmission electron microscopy in cross section view reveals that the elongated α-Si3N4 crystallites are formed on the surface of the nitrided SiO2/Si (110) substrate without any interlayers between Si3N4 and Si, and the longitudinal direction of α-Si3N4 appears mainly along <112¯0>, which is approximately parallel to Si <11¯0>.
      Citation: Coatings
      PubDate: 2021-10-14
      DOI: 10.3390/coatings11101251
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1252: Dataset on a Small-Scale Film-Coating
           Process Developed for Self-Expanding 4D Printed Drug Delivery Devices

    • Authors: Marco Uboldi, Alice Melocchi, Saliha Moutaharrik, Matteo Cerea, Andrea Gazzaniga, Lucia Zema
      First page: 1252
      Abstract: Film-coating is widely applied in pharmaceutics to enhance aspect/taste and mechanical properties of dosage forms, to protect them from the environment and to modify their release performance. In this respect, a film-coating process was recently involved in the development of 4D printed prolonged-release systems intended for organ retention. During coating processes, liquid formulations are sprayed onto moving cores, whose shape, weight and surface characteristics are essential to attain a homogeneous film. Devices of complex shapes, composed of smart materials and fabricated by hot-processing techniques, such as extrusion and fused deposition modeling 3D printing, might be poorly compatible with the requirements of traditional coating methods, e.g., need for spherical substrates with smooth surface and stable under process temperatures. This work was aimed at evaluating, at a small scale level, the feasibility of a versatile equipment for film-coating of rod-shaped extruded and printed prototypes with different section. Equipment design and set up of process parameters were performed starting from polymeric solutions and suspensions and selecting as cores 50 mm-long rod-shaped samples based on shape memory poly(vinyl alcohol). Integrity and thickness of the applied layer and its impact on shape memory and release performance of prototypes were investigated.
      Citation: Coatings
      PubDate: 2021-10-14
      DOI: 10.3390/coatings11101252
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1253: Oxygen Barrier Performance of Poly(vinyl
           alcohol) Coating Films with Different Induced Crystallinity and Model
           Predictions

    • Authors: Alamin Idris, Adrian Muntean, Beko Mesic, Magnus Lestelius, Asif Javed
      First page: 1253
      Abstract: The presence of the crystalline regions in poly(vinyl alcohol) coating films acts as barrier clusters forcing the gas molecules to diffuse in a longer pathway in the amorphous region of the polymer, where diffusivity and solubility are promoted in comparison. Evaluating the influence of crystalline regions on the oxygen barrier property of a semi-crystalline polymer is thus essential to prepare better coating films. Poly(vinyl alcohol) coating films with varying induced crystallinity were prepared on a polyethylene terephthalate (PET) substrate by drying at different annealing temperatures for 10 min. The coating films were first delaminated from the PET substrate and then characterized using Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and X-ray diffraction (XRD) techniques to determine and confirm the induced percentage of crystallinity. The barrier performance of the coating films, i.e., the oxygen transmission rate (OTR), was measured at room temperature. Results showed a decrease in the OTR values of poly(vinyl alcohol) film with an increase in the degree of crystallinity of the polymer matrix. Tortuosity-based models, i.e., modified Nielsen models, were adopted to predict the barrier property of the semi-crystalline PVOH film with uniform or randomly distributed crystallites. A modified Nielsen model for orderly distributed crystallites with an aspect ratio of 3.4 and for randomly distributed crystallites with an aspect ratio of 10.4 resulted in a good correlation with the experimental observation. For the randomly distributed crystallites, lower absolute average relative errors of 4.66, 4.45, and 5.79% were observed as compared to orderly distributed crystallites when the degree of crystallinity was obtained using FTIR, DSC, and XRD data, respectively.
      Citation: Coatings
      PubDate: 2021-10-15
      DOI: 10.3390/coatings11101253
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1254: Relationship between Friction Coefficient
           and Surface Roughness of Stone and Ceramic Floors

    • Authors: Samsiya Khaday, Kai-Way Li, Lu Peng, Ching-Chung Chen
      First page: 1254
      Abstract: Slips and falls are common occupational incidents worldwide. The friction on a floor surface is one of the critical environmental factors affecting the risk of a slip. In this research, we conducted friction measurements on stone and ceramic floor tiles under dry, wet, and water–detergent (WD) solution covered conditions using a horizontal pull slip meter (HPS). Our purposes were to quantify the slip resistance of commonly used stone and ceramic floors under different surface conditions and to validate the curvilinear relationship between the coefficient of friction (COF) and surface roughness of the floors proposed in the literature. The COF data were analyzed together with a surface profile parameter (Ra) of the floor samples. The results showed that the COFs of the stone floors were significantly (p < 0.0001) higher than those of the ceramic floors. All the floors under the dry conditions were slip resistant when adopting the ANSI 1264.2 criterion. Two and five ceramic floors were not slip resistant under the wet and WD solution covered conditions, respectively. Three polynomial regression equations were established to describe the relationship between the COF and Ra. The curvilinear functions of these models indicate that the three-zone (initial growth, steady-growth, and plateau) concept concerning the COF–Ra relationship in the literature was valid when static COF values measured using an HPS were adopted. In addition, the three-zone concept was valid not only on WD solution covered surfaces but also on dry and wet surfaces.
      Citation: Coatings
      PubDate: 2021-10-15
      DOI: 10.3390/coatings11101254
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1255: A Comparative Study of the Mechanical
           Properties of Selected Dental Composites with a Dual-Curing System with
           Light-Curing Composites

    • Authors: Monika Domarecka, Agata Szczesio-Wlodarczyk, Michał Krasowski, Magdalena Fronczek, Tomasz Gozdek, Jerzy Sokolowski, Kinga Bociong
      First page: 1255
      Abstract: Dual-curing composites have a wide spectrum of use in practice (rebuilding, reconstruction, and luting). The characterization of this type of material and comparative study of selected mechanical properties with light-cured materials were carried out for this paper. In this study, we used six materials with a dual-cure system—Bulk EZ, Fill-Up!, StarFill 2B, Rebilda DC, MultiCore Flow, Activa Bioactive-Restorative—and three light-cured materials—Filtek Bulk Fill Posterior, Charisma Classic, and G-aenial Universal Flo. The materials were conditioned for 24 h in water at 37 °C before testing. Selected material properties were determined: three-point bending flexural strength, diametral tensile strength, hardness, microhardness, and shrinkage stress. The highest three-point bending flexural strength (TPB) was 137.0 MPa (G-aenial Universal Flo), while the lowest amounted to 86.5 MPa (Activa Bioactive). The diametral tensile strength (DTS) values were in a range from 39.2 MPa (Rebilda DC) to 54.1 MPa (Charisma Classic). The lowest hardness (HV) value of 26 was obtained by the Activa Bioactive material, while the highest values were recorded for Filtek Bulk Fill Posterior and Charisma Classic-53. The shrinkage stress of the tested materials ranged from 6.3 MPa (Charisma Classic) to 13.2 MPa (G-aenial Universal Flo). Dual-curing composites were found to have similar properties to light-cured composites.
      Citation: Coatings
      PubDate: 2021-10-15
      DOI: 10.3390/coatings11101255
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1256: Microstructure and Oxidation Behavior of
           Metal-Modified Mo-Si-B Alloys: A Review

    • Authors: Laihao Yu, Fuqiang Shen, Tao Fu, Yingyi Zhang, Kunkun Cui, Jie Wang, Xu Zhang
      First page: 1256
      Abstract: With the rapid development of the nuclear industry and the aerospace field, it is urgent to develop structural materials that can work in ultra-high temperature environments to replace nickel-based alloys. Mo-Si-B alloys are considered to have the most potential for new ultra-high temperature structural material and are favored by researchers. However, the medium-low temperature oxidizability of Mo-Si-B alloys limits their further application. Therefore, this study carried out extensive research and pointed out that alloying is an effective way to solve this problem. This work provided a comprehensive review for the microstructure and oxidation resistance of low silicon and high silicon Mo-Si-B alloys. Moreover, the influence of metallic elements on the microstructure, phase compositions, oxidation kinetics and behavior of Mo-Si-B alloys were also studied systematically. Finally, the modification mechanism of metallic elements was summarized in order to obtain Mo-Si-B alloys with superior oxidation performance.
      Citation: Coatings
      PubDate: 2021-10-15
      DOI: 10.3390/coatings11101256
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1257: Corrosion Improvement of 304L Stainless
           Steel by ZrSiN and ZrSi(N,O) Mono- and Double-Layers Prepared by Reactive
           Cathodic Arc Evaporation

    • Authors: Mihaela Dinu, Anca Constantina Parau, Alina Vladescu, Adrian Emil Kiss, Iulian Pana, Emile S. Massima Mouele, Leslie Felicia Petrik, Viorel Braic
      First page: 1257
      Abstract: Zr-based nitrides and oxynitrides were deposited by reactive cathodic arc evaporation in monolayer and double-layer structures with the aim of increasing the corrosion protection of 304L stainless steel (SS) in a biomedical aggressive environment. All coatings had a total thickness of 1.2 µm. Compared to the bare substrate, the surface roughness of the coated samples was higher, the presence of microdroplets being revealed by scanning electron micrography (SEM). The X-ray diffraction investigation of the ZrN phases revealed that the peaks shifted towards lower Bragg angles and the lattice constants increased as a result of Si and O2 inclusion in ZrN lattice, and of the ion bombardment characteristic of the cathodic arc method, augmented by the applied bias substrate. SS/ZrSiN/ZrSi(N,O) showed the best corrosion performance in an acidic environment (0.9% NaCl and 6% H2O2; pH = 4), which was ascribed to the blocking effect of the interfaces, which acted as a corrosion barrier for the electrolyte ingress. Moreover, the aforementioned bilayer had the highest amount of Si and O in the composition of the top layer, forming a stable passive layer with beneficial effects on corrosion protection.
      Citation: Coatings
      PubDate: 2021-10-15
      DOI: 10.3390/coatings11101257
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1258: Durable Superhydrophobic Coating for
           Efficient Microplastic Removal

    • Authors: Oriol Rius-Ayra, Alisiya Biserova-Tahchieva, Nuria Llorca-Isern
      First page: 1258
      Abstract: The pollution caused by microplastics around the world is an increasingly significant issue that has to be tackled with different methods and technologies. Here, we report a straightforward and rapid process combining electrodeposition and electrophoresis to produce a durable superhydrophobic coating on an aluminum substrate (UNS A91070) that has a static contact angle (153°), sliding angle (1°), and contact angle hysteresis (1°). Field emission scanning electron microscopy and high-resolution transmission electron microscopy showed the presence of a hierarchical structure with nanolayers that were 70 nm thick. The chemical composition was also analyzed using attenuated total reflectance-Fourier transform infrared spectroscopy and high-resolution X-ray photoelectron spectroscopy, which revealed that the hierarchical structure was composed of zinc laurate (Zn(C11H20COO)2) that decreased the surface free energy of the system. Moreover, the coating showed high durability against abrasion caused by the P1200 SiC paper due to the presence of TiO2 particles in the upper layers as well as the homogeneous chemical composition of the hierarchical structure. Finally, taking advantage of the superoleophilic properties of superhydrophobic surfaces, the ability of the coating to remove high-density polyethylene microplastics from water was studied.
      Citation: Coatings
      PubDate: 2021-10-16
      DOI: 10.3390/coatings11101258
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1259: Melioration of Electrical and Optical
           Properties of Al and B Co-Doped ZnO Transparent Semiconductor Thin Films

    • Authors: Chien-Yie Tsay, Shih-Hsun Yu
      First page: 1259
      Abstract: Undoped, Al-doped and Al-B co-doped ZnO transparent semiconductor thin films were deposited on glass substrates by sol-gel method and spin coating technique. This study investigated the influence of Al (2 at.%) doping and Al (2 at.%)-B (1 or 2 at.%) co-doping on the microstructural, surface morphological, electrical and optical properties of the ZnO-based thin films. XRD analysis indicated that all as-prepared ZnO-based thin films were polycrystalline with a single-phase hexagonal wurtzite structure. The substitution of extrinsic dopants (Al or Al-B) into ZnO thin films can significantly degrade the crystallinity, refine the microstructures, improve surface flatness, enhance the optical transparency in the visible spectrum and lead to a shift in the absorption edge toward the short-wavelength direction. Experimental results showed that the Al-doped and Al-B co-doped ZnO thin films exhibited high average transmittance (>91.3%) and low average reflectance (<10%) in the visible region compared with the ZnO thin film. The optical parameters, including the optical bandgap, Urbach energy, extinction coefficient and refractive index, changed with the extrinsic doping level. Measured results of electrical properties revealed that the singly doped and co-doped samples exhibited higher electron concentrations and lower resistivities than those of the undoped sample and suggested that 2 at.% Al and 1 at.% B were the optimum dopant concentrations for achieving the best electrical properties in this study.
      Citation: Coatings
      PubDate: 2021-10-16
      DOI: 10.3390/coatings11101259
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1260: Application of the Electrochemical
           Permeation Method for Hydrogen Diffusion Coefficient Determination in
           Pipeline Steel 10G2

    • Authors: Vladislav I. Borodin, Aleksandr V. Lun-Fu, Victor N. Kudiiarov, Andrey M. Lider, Ivan S. Sakvin, Mikhail A. Bubenchikov, Dmitry S. Kaparulin, Vyacheslav A. Ovchinnikov
      First page: 1260
      Abstract: In this article, we conduct research on the effect of corrosion tests on the hydrogen diffusion process in gas steel in electrochemical permeability tests. This tests show that a long corrosion test time reduces the hydrogen diffusion coefficient by an order of magnitude, indicating the formation of aging defects in the steel. During operation, the diffusion coefficient decreases by two orders of magnitude, which also indicates the formation of a large number of defects in the steel. Consequently, based on the change in the diffusion coefficient in the material, it is possible to assess the degree of material failure.
      Citation: Coatings
      PubDate: 2021-10-16
      DOI: 10.3390/coatings11101260
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1261: Understanding the Relations between Surface
           Stress State and Microstructure Feature for Enhancing the Fatigue
           Performance of TC6 Titanium Alloy

    • Authors: Song Shu, Xin Huang, Zonghui Cheng, Yizhou Shen, Zhaoru He, Weilan Liu
      First page: 1261
      Abstract: Fatigue performance has always been an important factor affecting the application of titanium alloy. The service life of TC6 titanium alloy is easily reduced under a continuously alternating load. Therefore, there is an urgent need for a new method to improve fatigue performance. Laser shock peening (LSP) is a widely proposed method to enhance the fatigue performance. Here, through experiments and finite element simulations, it was found that LSP can prolong the fatigue life of TC6 by improving the surface stress state. In strengthening processes, the generation of residual stress was mainly attributed to the change of microstructure, which could be reflected by the statistical results of grain sizes. The content of grains with a size under 0.8 μm reached 78%, and the microhardness value of treated TC6 was 18.7% higher than that of an untreated sample. In addition, the surface residual compressive stress was increased to −600 MPa at the depth of 1500 μm from the surface. On this basis, the fatigue life was prolonged to 135%, and the ultimate fracture macroscopic was also changed. With the treatment of LSP, the fatigue performance of TC6 is highly promoted. The strengthening mechanism of LSP was established with the aim of revealing the relationship between microstructure and stress state for enhancing the fatigue performance in whatever shapes.
      Citation: Coatings
      PubDate: 2021-10-18
      DOI: 10.3390/coatings11101261
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1262: Excellent Properties of Ni-15 wt.% W Alloy
           Electrodeposited from a Low-Temperature Pyrophosphate System

    • Authors: Changwei Su, Zhaoyao Sa, Yangyang Liu, Linfu Zhao, Fengjing Wu, Wei Bai
      First page: 1262
      Abstract: Electrodeposited Ni-W alloy coatings are considered to be one of the most suitable candidate coatings to replace carcinogenic hexavalent chromium coatings. In this work, Ni-W alloys are electrodeposited from pyrophosphate baths containing different concentrations of Na2WO4 2H2O (CW) at 40 °C. Both CW and the applied current density can affect the W content in the coatings. The effect of CW becomes weaker with the increased current density. The Ni-W alloys with 15 ± 5 wt.% W (Ni-15 wt.% W) are obtained from the bath containing 40 g L−1 CW at a high current of 8 A dm−2. The microhardness, corrosion resistance and hydrogen evolution reaction (HER) are measured with a microhardness tester and an electrochemical workstation. The modified properties are studied by heat treatment from 200 to 700 °C. The highest microhardness of 895.62 HV and the better HER property is presented after heat treatment at 400 °C, while the best corrosion resistance in 3.5 wt.% NaCl solution appears at 600 °C.
      Citation: Coatings
      PubDate: 2021-10-18
      DOI: 10.3390/coatings11101262
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1263: Prediction of Dissolved Impurities and
           Movement of Oxide Particles in the Primary Circuit of LBE Fast Reactor

    • Authors: Jiewei Wu, Rongjun Wu, Yuqing Wang, Jianbo He, Chen Hu, Xian Zeng, Muyi Ni
      First page: 1263
      Abstract: To better understand the corrosion and corrosion products behavior in the primary circuit of lead-bismuth eutectic (LBE) coolant reactor, the concentration distribution of soluble impurities and the transport of solid particles are investigated through the finite-element method. An axisymmetric model of the primary circuit of an LBE reactor was constructed to accelerate the calculation of the thermal hydraulic filed of the circuit. The saturation concentration of solute Fe, Cr and Ni in LBE coolant are identified through the equilibrium of their oxides and PbO, and the very different saturation concentrations of Fe/Cr/Ni in LBE will lead to significant element-selective corrosion. The migration of solid oxide particles in the primary circuit is also investigated by the Euler–Lagrange tracing model. The simulation shows that driving force for the movement of particles >100 μm is buoyancy, which lets particles float on a free surface, while particles <10 μm tend to suspend in coolant. However, the behavior of particles also depends on the formation position, the particles formed above the core have a high possibility of re-entering in the core.
      Citation: Coatings
      PubDate: 2021-10-18
      DOI: 10.3390/coatings11101263
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1264: Microfabrication of VO2 Thin Films via a
           Photosensitive Sol-Gel Method

    • Authors: Chuanbao Wu, Yunwei Wang, Guangqiang Ma
      First page: 1264
      Abstract: VO2 films are widely used in photoelectric switches, smart glasses, storage media, and terahertz communications. In these applications, microfabrication technology is a very important process for producing microdevices or even improving film properties. In this paper, a novel photoetching microfabrication method is proposed for VO2 thin films. First, a VO2 precursor sol with ultraviolet photosensitivity was prepared using vanadyl acetylacetonate as the raw material and anhydrous methanol as the solvent. The dip-coated VO2 gel film can be directly subjected to photolithography processing without coating additional photoresist by using the photosensitive sol. A fine pattern on the VO2 film with good phase-transition performance can be obtained after annealing in a nitrogen atmosphere at 550 °C for 1 h. This method can be used to prepare grating, microarray, and various other fine patterns with the remarkable advantages of a low cost and simplified process, and the as-obtained material performances are unaffected using the method. It is a potential alternative method for optics, electronics, and magnetics devices based on VO2 thin films.
      Citation: Coatings
      PubDate: 2021-10-18
      DOI: 10.3390/coatings11101264
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1265: Measurement of Stress Optic Coefficient for
           Thermal Barrier Coating Based on Terahertz Time-Domain Spectrum

    • Authors: Zong Wang, Yanheng Zhang, Ning Lu, Zhiyong Wang, Wei Qiu
      First page: 1265
      Abstract: The residual stress introduced inside the thermal barrier coating (TBC) top coating during manufacturing and service processes is one of the main causes of thermal barrier failure. Therefore, a nondestructive and accurate measurement of the residual stress in top coating is essential for the evaluation of TBC life. The terahertz time-domain spectroscopy (THz-TDS) technique, which is based on the calibration or measurement of the stress optical coefficients of the measured materials, is applicable to the measuring of internal stress of nonmetal materials. In this work, to characterize the internal stress in TBC, the stress optic coefficient of the TBC top coating was measured by reflection-type THz-TDS. First, the mechanics model for the internal stress measurement in a TBC top coating was derived based on the photoelastic theory. Then, the THz time-domain spectra of TBC specimens under different loadings were measured in situ by a reflection-type THz-TDS system. Finally, the unimodal fitting, multimodal fitting and barycenter methods were used to carry out the data processing of the THz time-domain spectral-characteristic peaks. By comparing the processed results, the results using the barycenter method were regarded as the calibrated stress optical coefficient of the TBC due to the method’s sufficient accuracy and stability.
      Citation: Coatings
      PubDate: 2021-10-18
      DOI: 10.3390/coatings11101265
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1266: Properties of Al2O3 Thin Films Grown by
           PE-ALD at Low Temperature Using H2O and O2 Plasma Oxidants

    • Authors: Jhonathan Castillo-Saenz, Nicola Nedev, Benjamín Valdez-Salas, Mario Curiel-Alvarez, María Isabel Mendivil-Palma, Norberto Hernandez-Como, Marcelo Martinez-Puente, David Mateos, Oscar Perez-Landeros, Eduardo Martinez-Guerra
      First page: 1266
      Abstract: Al2O3 layers with thicknesses in the 25–120 nm range were deposited by plasma enhanced atomic layer deposition at 70 °C. Trimethylaluminum was used as organometallic precursor, O2 and H2O as oxidant agents and Ar as a purge gas. The deposition cycle consisted of 50 ms TMA pulse/10 s purge time/6 s of plasma oxidation at 200 W/10 s purge time. The optical constants and thicknesses of the grown layers were determined by spectroscopic ellipsometry, while the roughness was measured by atomic force microscopy, giving RMS values in the 0.29–0.32 nm range for films deposited under different conditions and having different thicknesses. High transmittance, ~90%, was measured by UV–Vis spectroscopy. X-ray photoelectron spectroscopy revealed that, with both types of oxidants, the obtained films are close to stoichiometric composition and, with high purity, no carbon was detected. Electrical characterization showed good insulating properties of both types of films, though the H2O oxidant leads to better I-V characteristics.
      Citation: Coatings
      PubDate: 2021-10-19
      DOI: 10.3390/coatings11101266
      Issue No: Vol. 11, No. 10 (2021)
       
  • Coatings, Vol. 11, Pages 1267: Preharvest Application of Hexanal as a
           Surface Treatment Improved the Storage Life and Quality of Mango Fruits

    • Authors: Palpandian Preethi, Kadambavanasundaram Soorianathasundaram, Athipathi Sadasakthi, Kizhaeral Sevathapandian Subramanian, Sanikommu Vijay Rakesh Reddy, Gopinadhan Paliyath, Jayasankar Subramanian
      First page: 1267
      Abstract: Mango is a highly preferred seasonal tropical fruit with a maximum shelf-life of five to seven days. Hexanal is a plant volatile compound assayed in green tissues and showing significance in enhancing storage life and fruit quality attributes by preserving membrane integrity. This experiment explored the effect of the pre-harvest application of an aqueous hexanal composition (active ingredient: 0.02% hexanal) in altering the post-harvest storage behavior of four mango cultivars. The pre-harvest application of the hexanal formulation to the fruit surface twice before the harvest date drastically slowed down the physiological loss in weight by 70% to 80%, and reduced the ethylene evolution rate by two to three folds, respectively. The pre-harvest hexanal formulation spray combined with post-harvest cold storage prominently improved the storage life along with the total soluble solids, total sugars, ascorbic acid and carotenoid content compared to untreated fruits stored in ambient conditions. Though ripening coincides with the increased activity of enzymes, the hexanal formulation spray acts predominantly in bringing down the activities of fruit softening enzymes viz. pectinmethlyesterase (43%) and polygalacturonases (37%), and antioxidant enzymes viz. peroxidase (67%) and catalase (45%), respectively.
      Citation: Coatings
      PubDate: 2021-10-19
      DOI: 10.3390/coatings11101267
      Issue No: Vol. 11, No. 10 (2021)
       
 
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