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  Subjects -> ENGINEERING (Total: 2417 journals)
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    - ELECTRICAL ENGINEERING (111 journals)
    - ENGINEERING (1267 journals)
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ENGINEERING (1267 journals)                  1 2 3 4 5 6 7 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 8)
3D Research     Hybrid Journal   (Followers: 21)
AAPG Bulletin     Hybrid Journal   (Followers: 8)
AASRI Procedia     Open Access   (Followers: 14)
Abstract and Applied Analysis     Open Access   (Followers: 3)
Aceh International Journal of Science and Technology     Open Access   (Followers: 2)
ACS Nano     Full-text available via subscription   (Followers: 274)
Acta Geotechnica     Hybrid Journal   (Followers: 7)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 7)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 3)
Acta Scientiarum. Technology     Open Access   (Followers: 3)
Acta Universitatis Cibiniensis. Technical Series     Open Access  
Active and Passive Electronic Components     Open Access   (Followers: 7)
Adaptive Behavior     Hybrid Journal   (Followers: 11)
Adıyaman Üniversitesi Mühendislik Bilimleri Dergisi     Open Access  
Adsorption     Hybrid Journal   (Followers: 4)
Advanced Engineering Forum     Full-text available via subscription   (Followers: 7)
Advanced Journal of Graduate Research     Open Access  
Advanced Science     Open Access   (Followers: 5)
Advanced Science Focus     Free   (Followers: 5)
Advanced Science Letters     Full-text available via subscription   (Followers: 10)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 7)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 18)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Complex Systems     Hybrid Journal   (Followers: 7)
Advances in Engineering Software     Hybrid Journal   (Followers: 27)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 17)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 13)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 21)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 22)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 29)
Advances in Operations Research     Open Access   (Followers: 12)
Advances in OptoElectronics     Open Access   (Followers: 6)
Advances in Physics Theories and Applications     Open Access   (Followers: 13)
Advances in Polymer Science     Hybrid Journal   (Followers: 43)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Remote Sensing     Open Access   (Followers: 44)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aerobiologia     Hybrid Journal   (Followers: 3)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 6)
AIChE Journal     Hybrid Journal   (Followers: 35)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access   (Followers: 1)
Alexandria Engineering Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 26)
American Journal of Engineering and Applied Sciences     Open Access   (Followers: 10)
American Journal of Engineering Education     Open Access   (Followers: 9)
American Journal of Environmental Engineering     Open Access   (Followers: 16)
American Journal of Industrial and Business Management     Open Access   (Followers: 24)
Analele Universitatii Ovidius Constanta - Seria Chimie     Open Access  
Annals of Combinatorics     Hybrid Journal   (Followers: 4)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of Regional Science     Hybrid Journal   (Followers: 7)
Annals of Science     Hybrid Journal   (Followers: 7)
Antarctic Science     Hybrid Journal   (Followers: 1)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applicable Analysis: An International Journal     Hybrid Journal   (Followers: 1)
Applied Catalysis A: General     Hybrid Journal   (Followers: 6)
Applied Catalysis B: Environmental     Hybrid Journal   (Followers: 18)
Applied Clay Science     Hybrid Journal   (Followers: 6)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 11)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 4)
Applied Nanoscience     Open Access   (Followers: 8)
Applied Network Science     Open Access   (Followers: 3)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Physics Research     Open Access   (Followers: 5)
Applied Sciences     Open Access   (Followers: 3)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4)
Arabian Journal for Science and Engineering     Hybrid Journal   (Followers: 5)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 5)
Archives of Foundry Engineering     Open Access  
Archives of Thermodynamics     Open Access   (Followers: 8)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ASEE Prism     Full-text available via subscription   (Followers: 3)
Asia-Pacific Journal of Science and Technology     Open Access  
Asian Engineering Review     Open Access  
Asian Journal of Applied Science and Engineering     Open Access   (Followers: 1)
Asian Journal of Applied Sciences     Open Access   (Followers: 2)
Asian Journal of Biotechnology     Open Access   (Followers: 8)
Asian Journal of Control     Hybrid Journal  
Asian Journal of Current Engineering & Maths     Open Access  
Asian Journal of Technology Innovation     Hybrid Journal   (Followers: 8)
Assembly Automation     Hybrid Journal   (Followers: 2)
at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
ATZagenda     Hybrid Journal  
ATZextra worldwide     Hybrid Journal  
Australasian Physical & Engineering Sciences in Medicine     Hybrid Journal   (Followers: 1)
Australian Journal of Multi-Disciplinary Engineering     Full-text available via subscription   (Followers: 2)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 9)
Avances en Ciencias e Ingeniería     Open Access  
Balkan Region Conference on Engineering and Business Education     Open Access   (Followers: 1)
Bangladesh Journal of Scientific and Industrial Research     Open Access  
Basin Research     Hybrid Journal   (Followers: 5)
Batteries     Open Access   (Followers: 6)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 28)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 4)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (Followers: 1)
BER : Motor Trade Survey     Full-text available via subscription  
BER : Retail Sector Survey     Full-text available via subscription   (Followers: 1)
BER : Retail Survey : Full Survey     Full-text available via subscription   (Followers: 1)
BER : Survey of Business Conditions in Manufacturing : An Executive Summary     Full-text available via subscription   (Followers: 3)
BER : Survey of Business Conditions in Retail : An Executive Summary     Full-text available via subscription   (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  
Biofuels Engineering     Open Access   (Followers: 1)
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 11)
Biomedical Engineering     Hybrid Journal   (Followers: 15)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 13)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 5)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 21)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 37)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 8)
Biomedical Science and Engineering     Open Access   (Followers: 4)
Biomedizinische Technik - Biomedical Engineering     Hybrid Journal   (Followers: 1)
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 2)
Biotechnology Progress     Hybrid Journal   (Followers: 40)
Bitlis Eren University Journal of Science and Technology     Open Access  
Boletin Cientifico Tecnico INIMET     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)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 12)
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 13)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 14)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal   (Followers: 2)
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 31)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 42)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 6)
Case Studies in Thermal Engineering     Open Access   (Followers: 5)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 7)
Catalysis Science and Technology     Free   (Followers: 8)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 7)
CEAS Space Journal     Hybrid Journal   (Followers: 2)
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 3)
Central European Journal of Engineering     Hybrid Journal  
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (Followers: 2)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
Chinese Journal of Engineering     Open Access   (Followers: 2)
Chinese Science Bulletin     Open Access   (Followers: 1)
Ciencia e Ingenieria Neogranadina     Open Access  
Ciencia en su PC     Open Access   (Followers: 1)
Ciencias Holguin     Open Access   (Followers: 3)
CienciaUAT     Open Access   (Followers: 1)
Cientifica     Open Access  
CIRP Annals - Manufacturing Technology     Full-text available via subscription   (Followers: 11)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 13)
City, Culture and Society     Hybrid Journal   (Followers: 21)
Clay Minerals     Full-text available via subscription   (Followers: 10)
Clean Air Journal     Full-text available via subscription   (Followers: 1)
Clinical Science     Full-text available via subscription   (Followers: 9)
Coal Science and Technology     Full-text available via subscription   (Followers: 3)
Coastal Engineering     Hybrid Journal   (Followers: 11)
Coastal Engineering Journal     Hybrid Journal   (Followers: 6)
Coatings     Open Access   (Followers: 4)
Cogent Engineering     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Color Research & Application     Hybrid Journal   (Followers: 2)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 14)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 14)
Communications Engineer     Hybrid Journal   (Followers: 1)
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: 7)
Composite Structures     Hybrid Journal   (Followers: 276)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 212)
Composites Part B : Engineering     Hybrid Journal   (Followers: 248)
Composites Science and Technology     Hybrid Journal   (Followers: 195)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access   (Followers: 1)
Computational Geosciences     Hybrid Journal   (Followers: 16)
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computational Science and Discovery     Full-text available via subscription   (Followers: 2)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 8)
Computer Science and Engineering     Open Access   (Followers: 19)
Computers & Geosciences     Hybrid Journal   (Followers: 31)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 8)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 5)
Computers and Geotechnics     Hybrid Journal   (Followers: 11)
Computing and Visualization in Science     Hybrid Journal   (Followers: 7)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 33)
Conciencia Tecnologica     Open Access  
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 8)

        1 2 3 4 5 6 7 | Last

Journal Cover
Coatings
Number of Followers: 4  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2079-6412
Published by MDPI Homepage  [202 journals]
  • Coatings, Vol. 8, Pages 227: Hot Embossing for Whole Teflon
           Superhydrophobic Surfaces

    • Authors: Jie Li, Wentao Yu, Deyin Zheng, Xin Zhao, Chang-Hwan Choi, Guangyi Sun
      First page: 227
      Abstract: In this paper, we report a simple fabrication process of whole Teflon superhydrophobic surfaces, featuring high-aspect-ratio (>20) nanowire structures, using a hot embossing process. An anodic aluminum oxide (AAO) membrane is used as the embossing mold for the fabrication of high-aspect-ratio nanowires directly on a Teflon substrate. First, high-aspect-ratio nanowire structures of Teflon are formed by pressing a fluorinated ethylene propylene (FEP) sheet onto a heated AAO membrane at 340 °C, which is above the melting point of FEP. Experimental results show that the heating time and aspect ratios of nanopores in the AAO mold are critical to the fidelity of the hot embossed nanowire structures. It has also been found that during the de-molding step, a large adhesive force between the AAO mold and the molded FEP greatly prolongs the length of nanowires. Contact angle measurements indicate that Teflon nanowires make the surface superhydrophobic. The reliability and robustness of superhydrophobicity is verified by a long-term (~6.5 h) underwater turbulent channel flow test. After the first step of hot-embossing the Teflon nanowires, microstructures are further superimposed by repeating the hot embossing process, but this time with microstructured silicon substrates as micromolds and at a temperature lower than the melting temperature of the FEP. The results indicate that the hot embossing process is also an effective way to fabricate hierarchical micro/nanostructures of whole Teflon, which can be useful for applications of Teflon material, such as superhydrophobic surfaces.
      Citation: Coatings
      PubDate: 2018-06-22
      DOI: 10.3390/coatings8070227
      Issue No: Vol. 8, No. 7 (2018)
       
  • Coatings, Vol. 8, Pages 198: Anti- and De-Icing Behaviors of
           Superhydrophobic Fabrics

    • Authors: Yuyang Liu, Dong Song, Chang-Hwan Choi
      First page: 198
      Abstract: This paper reports the application of superhydrophobic coatings on cotton fabrics and their functionalities for anti- and de-icing efficacy. Superhydrophobic cotton fabrics with different water-repellent properties have been achieved by decorating the surface of pristine cotton fibers with ZnO structures of varying sizes and shapes through an in situ solution growth process, followed by the treatment of the surface with low-surface-energy coating such as Teflon. The surface morphology of the treated cotton fabrics was characterized using scanning electron microscopy (SEM). The surface wettability of the treated fabrics was evaluated through the measurement of static contact angle (SCA), contact angle hysteresis (CAH), and sliding angle (SA) of a water droplet. The anti- and de-icing behaviors of the treated fabrics were evaluated through both static (sessile droplet) and dynamic (spraying) tests. The results show that the superhydrophobic fabric with a higher SCA and the lower CAH/SA has superior anti- and de-icing behaviors in both the static and dynamic conditions. Compared to hard substrates, the soft, flexible, and porous (air-permeable) superhydrophobic fabrics can lead to broader applicability of textile-based materials for the design and fabrication of anti- and de-icing materials. Furthermore, the multi-scale surface structures of fabrics (fibers, yarns, and weaving constructions) combining with the hierarchical micro-nanostructures of the ZnO coating provides an ideal platform for anti-icing studies.
      Citation: Coatings
      PubDate: 2018-05-23
      DOI: 10.3390/coatings8060198
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 199: Effects of sp2/sp3 Ratio and Hydrogen Content
           on In Vitro Bending and Frictional Performance of DLC-Coated Orthodontic
           Stainless Steels

    • Authors: Takeshi Muguruma, Masahiro Iijima, Masahiro Kawaguchi, Itaru Mizoguchi
      First page: 199
      Abstract: This study investigated a diamond-like carbon (DLC) coating formed on stainless steels (disk and wire specimens) using a plasma-based ion implantation/deposition method with two different parameters (DLC-1, DLC-2). These specimens were characterized using high-resolution elastic recoil analysis, microscale X-ray photoelectron spectroscopy and nanoindentation testing to determine the hydrogen content, sp2/sp3 ratio and mechanical properties of the coating. Three-point bending and frictional properties were estimated. DLC-1 had a diamond-rich structure at the external surface and a graphite-rich structure at the inner surface, while DLC-2 had a graphite-rich structure at the external surface and a diamond-rich structure at the inner surface. Mean mechanical property values obtained for the external surface were lower than those for the inner surface in both types of DLC-coated specimens. The hydrogen content of DLC-2 was slightly higher versus DLC-1. Both DLC-coated wires produced a significantly higher elastic modulus according to the three-point bending test versus the non-coated wire. DLC-2 produced significantly lower frictional force than the non-coated specimen in the drawing-friction test. The coating of DLC-1 was partially ruptured by the three-point bending and drawing-friction tests. In conclusion, the bending and frictional performance of DLC-coated wire were influenced by the hydrogen content and sp2/sp3 ratio of the coating.
      Citation: Coatings
      PubDate: 2018-05-24
      DOI: 10.3390/coatings8060199
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 200: The Effect of Processing Parameters on the
           Formation and Properties of Al/Ni Core-Shell Pigments via a Galvanic
           Displacement Method

    • Authors: Le Yuan, Min Zhou, Can Wang, Qinyong Zhang, Xiaolong Weng, Longjiang Deng
      First page: 200
      Abstract: Al/Ni bimetallic core-shell pigments with flake Al particle as core and metallic Ni as shell were synthesized via a galvanic displacement method and studied with X-ray diffraction, scanning electron micrograph (SEM), specific surface area analysis (BET), thermogravimetry-differential thermalanalysis (TG/DSC), and visible-near infrared-infrared reflectance spectroscopy. The influence of reactant ratio (Al:Ni2+) and order of addition on phase structure, surface morphology, optical properties, and high temperature oxidation resistance properties were studied systematically. The results show that the local concentration of Ni2+ at solid-liquid interfaces can be effectively modulated by adjusting the reactant ratio and order of addition. A high local concentration of Ni2+ improves the rate of displacement reaction resulting in more metallic Ni on the surface of the flake Al powders. This increases the relative content of Ni in the shell. The change of displacement reaction rate also leads to a different surface morphology and roughness of the Ni shell. The thick and rough Ni shell has a strong absorption extinction due to the intense light scattering and absorption-this substantially reduces the spectral reflectance of the flake Al core. Infrared reflectance in particular is influenced by light scattering and absorption of the rough surface. In addition, the Ni shell can enhance the high temperature oxidation resistance of the Al core by preventing contact between the metallic Al substrate and oxygen. The oxidation resistance is also associated with the processing parameters of the galvanic displacement reaction.
      Citation: Coatings
      PubDate: 2018-05-24
      DOI: 10.3390/coatings8060200
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 201: Adhesion Performance of Electrodeposited Ni
           Films with Different Treating Methods

    • Authors: Rui Liu, Yanyan Yuan, Hong Wang, Xi Guo
      First page: 201
      Abstract: The adhesion strength between thin films has a significant effect on performance of micro-devices. It is introduced that the effects of three pre-treatment methods: acid, pulse reverse current and anodic current, on the adhesion performance of electrodeposited Ni films on Ni substrate. The adhesion strength, surface and fracture morphology of the Ni films were investigated. The dense oxide films on the Ni substrate were removed effectively by using the anodic dissolution current method in the acidic chloride solutions. Meanwhile, the Ni films treated with specific treatment conditions produced different roughness, which was responsible for the improved adhesion strength. The adhesion strength of the Ni films increased up to 629.8 MPa when substrates were treated with anodic current density of 30 mA/cm2 for 10 min, which is nearly two times higher than that of films treated by 5 vol % HCl for 10 min. The results indicate that the anodic current treatment method effectively improves the adhesion strength of Ni films.
      Citation: Coatings
      PubDate: 2018-05-25
      DOI: 10.3390/coatings8060201
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 202: Tribocorrosion Properties of PEO Coatings
           Produced on AZ91 Magnesium Alloy with Silicate- or Phosphate-Based
           Electrolytes

    • Authors: Luca Pezzato, Dragos Vranescu, Marco Sinico, Claudio Gennari, Alessio Giorgio Settimi, Pietro Pranovi, Katya Brunelli, Manuele Dabalà
      First page: 202
      Abstract: In this work, the tribocorrosion behavior of plasma electrolytic oxidation (PEO)-coated AZ91 samples was studied. In particular, two different coatings were produced and compared. One was obtained with an alkaline electrolyte containing sodium phosphate, whereas the other one was produced with an alkaline electrolyte containing sodium silicate. The coatings were characterized with SEM-EDS and XRD techniques, and after the tribocorrosion tests, the wear scars were analyzed with SEM-EDS. The tribocorrosion behavior was evaluated measuring the OCP during a pin on disk test performed in an aggressive environment. Moreover, potentiodynamic polarization and electrochemical impedance spectroscopy tests were performed, to evaluate the corrosion resistance of the different samples in the absence of wear phenomena. The behavior of all the PEO-treated specimens was compared with the one of the untreated sample. A remarkable increase in the tribocorrosion performances after the PEO treatments was observed. Moreover, the samples obtained with the electrolyte containing silicates showed higher tribocorrosion performances.
      Citation: Coatings
      PubDate: 2018-05-25
      DOI: 10.3390/coatings8060202
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 203: Osteogenesis and Antibacterial Activity of
           Graphene Oxide and Dexamethasone Coatings on Porous Polyetheretherketone
           via Polydopamine-Assisted Chemistry

    • Authors: Ling Ouyang, Meiyao Qi, Shengnan Wang, Shan Tu, Bogang Li, Yi Deng, Weizhong Yang
      First page: 203
      Abstract: Endowing implants with antibacterial ability and osteogenic ability plays important roles in preventing post-operative bacterial contamination and facilitating integration between implants and osseous tissue, consequently reducing implant failure rates. In this study, we develop a facile and versatile strategy with dopamine as an auxiliary for construction of dexamethasone (Dex)/liposome porous coatings. In detail, the surfaces of sulfonated polyetheretherketone (SP) plates are coated with polydopamine firstly and then modified with graphene oxide (GO) and dexamethasone (Dex)-loaded liposome, which is verified by contact angle, X-ray photoelectron spectroscopy (XPS), attenuated total reflection infrared (ATR), and Raman spectra. The results of our study suggest that the GO and Dex are successfully coated on the samples’ surfaces. In vitro cell attachment, growth, differentiation, and apatite deposition tests all illustrate that the substrate coated with GO and Dex can significantly accelerate the proliferation and osteogenic differentiation of MC3T3 cells compared with the pristine sulfonated polyetheretherketone (PEEK). Additionally, it exhibits acceptable antibacterial activity against E. coli and S. aureus in vitro. Altogether, our results demonstrate that the modified GO- and Dex-loaded substrates are endowed with impressive biocompatibility and certain antibacterial qualities, making it possible for future application as a perspective implant material.
      Citation: Coatings
      PubDate: 2018-05-28
      DOI: 10.3390/coatings8060203
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 204: Application of Oxovanadium Complex Stabilized
           by N,N,N,N-Chelating Ligand in Air-Drying Paints

    • Authors: Iva Charamzová, Jaromír Vinklárek, Petr Kalenda, Jan Honzíček
      First page: 204
      Abstract: New vanadium-based drier, stabilized with macrocyclic chelating ligand, is described. Its drying activity was established on solvent-borne alkyd resins of different oil-length modified by soybean oil. The test coatings were characterized by standardized mechanical tests as well as spectroscopic methods. Time-resolved infrared spectroscopy was used for determination of kinetic parameters of the autoxidation process while the EPR (electron paramagnetic resonance) spectroscopy enabled confirmation of stability of oxovanadium(IV) species in the cured films. The obtained experimental data revealed promising catalytic activity of the oxovanadium(IV) compound stabilized with N,N,N,N-chelating ligand at low concentration. At 0.03 wt % of metal in dry matter content, it shows short total dry times not exceeding 12 h while commercial cobalt(II) 2-ethylhexanoate is, at the same concentration, considerably lower active with total dry times 15.4 h (alkyd of short oil-length) and >24 h (alkyd of medium oil-length).
      Citation: Coatings
      PubDate: 2018-05-28
      DOI: 10.3390/coatings8060204
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 205: Preparation and Photoluminescence of Tungsten
           Disulfide Monolayer

    • Authors: Yanfei Lv, Feng Huang, Luxi Zhang, Jiaxin Weng, Shichao Zhao, Zhenguo Ji
      First page: 205
      Abstract: Tungsten disulfide (WS2) monolayer is a direct band gap semiconductor. The growth of WS2 monolayer hinders the progress of its investigation. In this paper, we prepared the WS2 monolayer through chemical vapor transport deposition. This method makes it easier for the growth of WS2 monolayer through the heterogeneous nucleation-and-growth process. The crystal defects introduced by the heterogeneous nucleation could promote the photoluminescence (PL) emission. We observed the strong photoluminescence emission in the WS2 monolayer, as well as thermal quenching, and the PL energy redshift as the temperature increases. We attribute the thermal quenching to the energy or charge transfer of the excitons. The redshift is related to the dipole moment of WS2.
      Citation: Coatings
      PubDate: 2018-05-30
      DOI: 10.3390/coatings8060205
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 206: Surface Aging Effect on Tire/Pavement Noise
           Medium-Term Evolution in a Medium-Size City

    • Authors: Víctor F. Vázquez, Fernando Terán, Pedro Huertas, Santiago Expósito Paje
      First page: 206
      Abstract: This paper presents the geo-referenced acoustical results obtained throughout the close proximity noise (CPX) technique carried out on different urban sections included within the 2017 strategic noise mapping (Directive 2002/49/CE) in Ciudad Real, a Spanish medium-sized city. The employed methodology quantifies the tire/pavement noise generated in the contact between the tire and the surface of the studied sections. Measurements were carried out in different research campaigns between 2008 and 2015 (medium-term evolution). They give valuable information about the pavement-aging effect on its surface characteristics. Throughout these years, the acoustic situation of these sections has worsened mainly due to surface damage and higher mean profile depth (MPD) values, although the performance does not follow the same pattern in every section. The relationships between measured tire/pavement noise and theoretical environmental noise, just due to the geometric spreading of sound energy, is also studied in order to elaborate a simple rolling noise mapping and to assess the environmental noise evolution. Traffic noise plays the main role in the noise registered within the assessed sections, therefore, CPX assessment could be used by local authorities to take decisions regarding urban planning and traffic management, with the aim of reducing noise exposure from traffic.
      Citation: Coatings
      PubDate: 2018-05-30
      DOI: 10.3390/coatings8060206
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 207: Application of Nanofibrillated Cellulose on
           BOPP/LDPE Film as Oxygen Barrier and Antimicrobial Coating Based on Cold
           Plasma Treatment

    • Authors: Peng Lu, Mengya Guo, Zhijun Xu, Min Wu
      First page: 207
      Abstract: The application of nanofibrillated cellulose (NC) films in packaging industry has been hindered by its lack of heat-sealing ability. Incorporation of NC films with the biaxially oriented polypropylene/low density polyethylene (BOPP/LDPE) laminates can take advantage of each material and endow the films with novel functions for food packaging applications. In this study, a coating that consists of NC and nisin was applied onto a cold plasma treated BOPP/LDPE film to fabricate a novel active packaging with an improved oxygen barrier performance and an added antimicrobial effect. The results showed that cold plasma treatment improved the surface hydrophilicity of BOPP/LDPE films for better attachment of the coatings. NC coatings significantly enhanced oxygen barrier property of the BOPP/LDPE film, with an oxygen transmission rate as low as 24.02 cc/m2·day as compared to that of the non-coated one (67.03 cc/m2·day). The addition of nisin in the coating at a concentration of 5 mg/g caused no significant change in barrier properties but imparted the film excellent antimicrobial properties, with a growth inhibition of L. monocytogenes by 94%. All films exhibit satisfying mechanical properties and transparency, and this new film has the potential to be used as antimicrobial and oxygen barrier packaging.
      Citation: Coatings
      PubDate: 2018-05-30
      DOI: 10.3390/coatings8060207
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 208: Recent Progress in Preparation and Anti-Icing
           Applications of Superhydrophobic Coatings

    • Authors: Yuebin Lin, Haifeng Chen, Guanyu Wang, Aihui Liu
      First page: 208
      Abstract: Aircraft icing refers to ice formation and accumulation on the windward surface of aircrafts. It is mainly caused by the striking of unstable supercooled water droplets suspended in clouds onto a solid surface. Aircraft icing poses an increasing threat to the safety of flight due to the damage of aerodynamic shape. This review article provides a comprehensive understanding of the preparation and anti-icing applications of the superhydrophobic coatings applied on the surface of aircrafts. The first section introduces the hazards of aircraft icing and the underlying formation mechanisms of ice on the surface of aircrafts. Although some current anti-icing and de-icing strategies have been confirmed to be effective, they consume higher energy and lead to some fatigue damages to the substrate materials. Considering the icing process, the functional coatings similar to lotus leaf with extreme water repellency and unusual self-cleaning properties have been proposed and are expected to reduce the relied degree on traditional de-icing approaches and even to replace them in near future. The following sections mainly discuss the current research progress on the wetting theories of superhydrophobicity and main methods to prepare superhydrophobic coatings. Furthermore, based on the bouncing capacity of impact droplets, the dynamic water repellency of superhydrophobic coatings is discussed as the third evaluated parameter. It is crucial to anti-icing applications because it describes the ability of droplets to rapidly bounce off before freezing. Subsequently, current studies on the application of anti-icing superhydrophobic coatings including the anti-icing mechanisms and application status are introduced in detail. Finally, some limitations and issues related to the anti-icing applications are proposed to provide a future outlook on investigations of the superhydrophobic anti-icing coatings.
      Citation: Coatings
      PubDate: 2018-05-31
      DOI: 10.3390/coatings8060208
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 209: Corrosion Resistance of Waterborne Epoxy
           Coatings by Incorporation of Dopamine Treated Mesoporous-TiO2 Particles

    • Authors: Na Wang, Xinlin Diao, Jing Zhang, Ping Kang
      First page: 209
      Abstract: In this paper, waterborne epoxy (EP) coatings were modified by the incorporation of synthetic structure (DA/meso-TiO2) to improve the anticorrosion ability of waterborne epoxy coatings for steel structures. Fourier transform infrared spectroscopy (FTIR), nitrogen adsorption–desorption, X-ray diffraction (XRD) and thermo-gravimetric analyses (TGA) were used to characterize textural properties of DA/meso-TiO2. Corrosion performances of mild carbon steel coated samples were tested by salt spray tests and employing electrochemical impedance spectroscopy (EIS). FTIR, XRD, TGA and nitrogen adsorption–desorption attested to dopamine polymerization within the mesopores and on the surface of meso-TiO2. The results of EIS and salt spray test showed that the specimen coated with 1.0 wt % DA/meso-TiO2 exhibited optimum corrosion performance among other coating specimens.
      Citation: Coatings
      PubDate: 2018-05-31
      DOI: 10.3390/coatings8060209
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 210: Omnidirectional SiO2 AR Coatings

    • Authors: Sadaf Bashir Khan, Hui Wu, Zhengjun Zhang
      First page: 210
      Abstract: It is of great importance to develop antireflective (AR) coatings and techniques because improved optical performance has been progressively prerequisite for wide-ranging applications such as flat panel displays, optoelectronic devices or solar cells. Natural surroundings inspire researchers considerably to impersonate in order to provoke analogous characteristics via artificial approaches, which provide the opportunity for emerging techniques and development in material engineering. Herein, SiO2 antireflective (AR) coatings comprised of two layers were fabricated using a physical vapour deposition method via glancing angle. The top layer fabricated at an oblique angle of 80° and the bottom layer close to the substrate was deposited at a deposition angle of 0°. The experimental outcomes demonstrate that there is a slight influence on the refractive index of thin films by changing the morphology of nanostructures keeping deposition angles the same. The top layer shows a periodic arrangement of SiO2 nanostructures while the bottom stratum represents a SiO2 compact dense layer. The assembled bilayer SiO2 AR coating retains omnidirectional AR efficiency and tunability at a preferred wavelength range displaying <1% reflectance. Moreover, the fabricated omnidirectional SiO2 AR coatings have thermal stability up to 300 °C. These SiO2 AR coatings also possess negative temperature resistivity to withstand different cold storage conditions. Hence, the flexible and environmental adaptive SiO2 AR coating offers an intriguing route for imminent research in optics.
      Citation: Coatings
      PubDate: 2018-06-01
      DOI: 10.3390/coatings8060210
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 211: Characterization of Ultrasonic-Assisted
           Electrochemical Deposition of Ni-Co-ZrO2

    • Authors: Yiyong Wang, Xinyu Zhou, Zhipeng Liang, Hui Jin
      First page: 211
      Abstract: In order to evaluate the electrochemical behavior of nano-ZrO2 particles in the co-deposition process, revealing the electrocrystallization mechanism and electrodeposition parameters of composite coatings, cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) techniques were used to offer a favorable reference for electrochemical studies in an acidic amino sulfonate bath, and the kinetic parameters were calculated by fitting the experimental curves. The CV results suggested that the co-deposition of nano-ZrO2 particles and matrix metal caused the initial deposition potential of Ni2+ and Co2+ to shift to more positive values (−0.80 V vs SCE) while the nano-ZrO2 inhibited the reduction of H+ and decreased the cathodic polarization in co-deposition. The electrocrystallization of Ni-Co and Ni-Co-ZrO2 sedimentary layer were governed by the Scharifker–Hill instantaneous nucleation model, and the nucleation rate of composite coatings was higher at potentials ranging from −1.10 to −1.15 V, and nano-ZrO2 absorbed on an electrode surface promoted the nucleation/growth of Ni2+ and Co2+. However, nano-ZrO2 particles hindered the nucleation/growth of Ni2+ and Co2+ at −1.20 and −1.25 V vs. SCE; the calculated results were consistent with the theoretical analysis of experimental curves. An EIS test indicated that the incorporation of nano-ZrO2 particles into the matrix did not obviously effect the electric double layer at the electrode/electrolyte interface, but the charged transfer resistance of the composite was decreased in the electrodeposition.
      Citation: Coatings
      PubDate: 2018-06-01
      DOI: 10.3390/coatings8060211
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 212: Conductive Characteristics of Indium Tin
           

    • Authors: Dinh-Phuc Tran, Hung-I Lu, Chih-Kuang Lin
      First page: 212
      Abstract: The objective of this study is to investigate the effect of long-term static bending on the conductive characteristics of indium tin oxide (ITO) thin film in flexible optoelectronics. Two types of substrate are considered, namely ITO on polyethylene naphthalate (ITO/PEN) and ITO on polyethylene terephthalate (ITO/PET). Electrical properties of the ITO/PEN and ITO/PET sheets are measured in situ under static bending at various radii of curvature. Experimental results indicate that no significant change in electrical resistance of the ITO/PEN and ITO/PET sheets is found for compressive bending after 1000 h at a curvature radius of 10 mm or larger. However, the ITO/PEN and ITO/PET sheets are seriously damaged under a tensile bending of 10 mm radius and 5 mm radius, respectively. The given ITO/PET sheet exhibits a greater resistance to long-term mechanical bending than the ITO/PEN one, which is attributed to the effect of stiffness and thickness of substrate. As the given PET substrate has a lower stiffness and thickness than the PEN one, ITO thin film in the ITO/PET sheet has a smaller stress given a bending radius. Consequently, a smaller extent of change in the electrical conductance of ITO thin film is found in the ITO/PET sheet.
      Citation: Coatings
      PubDate: 2018-06-01
      DOI: 10.3390/coatings8060212
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 213: Superconducting Niobium Coatings Deposited on
           Spherical Substrates in Molten Salts

    • Authors: Anton Dubrovskiy, Maksim Okunev, Olga Makarova, Sergey Kuznetsov
      First page: 213
      Abstract: The interaction of substrates from ceramics, beryllium, and carbopyroceram with the electrolyte for the electrodeposition of niobium coatings was investigated. The corrosion resistance of spherical ceramic and beryllium samples with the protective molybdenum films obtained by magnetron sputtering was studied. The exfoliation of molybdenum film from ceramics and beryllium samples was observed after the experiments due to the interaction of substrates with the melt. It was found that the carbopyroceram did not corrode in the niobium containing melt and this material was chosen as the substrate for the electrodeposition of superconducting niobium coatings. The influence of the oxide ions on the electrochemical behavior of niobium complexes in the NaCl–KCl–NaF–K2NbF7 melt was studied. A special form of the cathode was constructed for the electrodeposition of niobium coatings on spherically shaped substrates. Electrodeposition of the niobium coatings on spheres 10 mm in diameter manufactured from carbopyroceram was carried out at 750 °C with the cathodic current density of 5 × 10−3–2 × 10−2 A·cm−2 and the electrolysis time of 8–12 h. Influence of the cathodic current density on the microstructure of niobium coatings was studied. The roughness, nonsphericity, and superconductive properties of niobium coatings were determined.
      Citation: Coatings
      PubDate: 2018-06-04
      DOI: 10.3390/coatings8060213
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 214: Characterization of Flake Boron Nitride
           Prepared from the Low Temperature Combustion Synthesized Precursor and Its
           Application for Dye Adsorption

    • Authors: Jinglong Qu, Qun Li, Chang Luo, Jin Cheng, Xinmei Hou
      First page: 214
      Abstract: Flake boron nitride (BN) in large yield was successfully synthesized at low temperature from the combustion synthesized precursor. The precursor was prepared by a low-temperature (350 °C) combustion synthesis (LCS) method using nitric acid (HNO3), urea (CO(NH2)2), boric acid (H3BO3), and glucose (C6H12O6·H2O) as starting materials. The precursor consists of B2O3 and amorphous carbon and the morphology is composed of blocks with average diameters of about 10 μm by statistical methods using SEM at different fields. Then BN was synthesized at 900 °C in NH3 at a heating rate of 5 °C min−1. The as-prepared BN possesses a flake morphology and high specific surface area up to 936 m2 g−1. It also has high density structural defects and abundant –NH2/–OH groups. The surface groups improve its water wettability and electronegativity, which contributes to the rapid and selective adsorption performance, especially towards the cationic dyes. When 4 mg of the sample was added into a 100 mL RhB solution with an initial concentration of 5 mg L−1, 95% of the RhB was removed within 1 min and the adsorption capacity is 125 mg g−1. Importantly, the sample can be regenerated by heating at 400 °C in air.
      Citation: Coatings
      PubDate: 2018-06-04
      DOI: 10.3390/coatings8060214
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 215: Surface Modification of Esophageal Stent
           Materials by a Drug-Eluting Layer for Better Anti-Restenosis Function

    • Authors: Yuxin Bai, Kun Zhang, Ru Xu, Hongtao Liu, Fangxia Guan, Huiwen Luo, Ye Chen, Jingan Li
      First page: 215
      Abstract: It is generally accepted that stent implantation is the mainstream therapy in clinics for esophageal cancer in the later period. However, the restenosis caused by tumor cells, epithelial cells, and fibroblasts seriously interferes with the stent medical application and limits its long-term services. To address this conundrum, a series of drug-eluting stents were invented and verified to be feasible in the early stage after implantation, but the limited drug loading and good cell compatibility of the stent materials may lead to more serious restenosis and further endanger the patient’s life. In previous work, we modified the esophageal stent material 317L stainless steel (317L SS) surface with a poly-dopamine/poly-ethylenimine layer (PDA/PEI), which had strong anti-tumor functions. In this contribution, we employed a usual drug in clinic, 5-fluorouracil (5-Fu), with series of density onto the PDA/PEI modified 317L SS to investigate the influence of 5-Fu immobilization on the anti-restenosis function. The surface characterization including 5-Fu quantity, atomic force microscopy (AFM). Water contact angle measurement indicated successful preparation of the PDA/PEI/5-Fu layers. The spectrophotometric characterization revealed that the immobilized 5-Fu rapidly released over 24 h. However, the Eca109, Het-1A, and L929 cells culture results suggested that the released 5-Fu made a significant contribution to improving the apoptosis and necrosis of these pathological cells, and the PDA/PEI/5-Fu layers maintain the consistent anti-restenosis function on their surfaces with the PDA/PEI layer after 24 h. All the results demonstrated the PDA/PEI/5-Fu layers’ excellent ability to suppress esophageal tumor cells, epithelial cells, and fibroblasts, suggesting a potential application on the surface modification of esophageal stents for better anti-restenosis function.
      Citation: Coatings
      PubDate: 2018-06-06
      DOI: 10.3390/coatings8060215
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 216: Improvement of Corrosion Resistance for Gray
           Cast Iron in Palm Biodiesel Application Using Thermoreactive Diffusion
           Niobium Carbide (NbC) Coating

    • Authors: Ariel Amaya, Oscar Piamba, Jhon Olaya
      First page: 216
      Abstract: Biodiesel is a renewable fuel consisting of alkyl esters, which show a higher corrosive behavior when compared with a diesel fuel. The corrosive processes by biodiesel affects the processing infrastructure of this biofuel and mechanical parts of automotives. Valves, engine blocks, and cylinder liners are gray cast iron components affected by biodiesel corrosion. The corrosion resistance of niobium carbide (NbC) coatings deposited using thermoreactive diffusion (TRD) on gray cast iron in continuous contact with diesel fuel and palm biodiesel was studied. Both coated and uncoated samples were subjected to immersion tests, cyclic oxidation at 473 K, and an electrochemical impedance spectroscopy (EIS) test. The coatings were characterized by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). Both the rate of corrosion by immersion and the resistance to polarization via EIS showed the favorable behavior of niobium carbide coatings against the corrosion of palm biodiesel. The corrosion rate on samples coated with niobium carbide was three times lower than that of the gray casting samples. These results allow the conclusion that niobium carbide coatings could be a viable alternative to lessening the corrosive effects of palm biodiesel in the applications where gray cast iron is used in continuous contact with biofuel.
      Citation: Coatings
      PubDate: 2018-06-07
      DOI: 10.3390/coatings8060216
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 217: On the Activity Enhancing Role of Iron Oxide
           for Noble Metal Oxidation Catalysts: A CVD-Based Study with Differently
           Structured Combinations of Pt and FeOx Coatings on Al2O3

    • Authors: Laila Pasin, Jörg Meyer, Elisabeth Eiche, Gerhard Kasper
      First page: 217
      Abstract: With regard to the catalysis of oxidation reactions by noble metals, the addition of FeOx to an Al2O3-supported Pt catalyst is known to be energetically more favorable compared to only Pt. In this work, different process routes for the preparation of such Fe-promoted Pt/Al2O3 catalysts via atmospheric chemical vapor deposition (CVD) in a fluidized bed were explored. Specifically, the question of whether it would be advantageous to deposit the Fe before, along with, or after the Pt was addressed, and new information was obtained about the optimum FeOx–Pt interface and mixing ratio. Vapors of Trimethyl(methylcyclopentadienyl)platinum(IV) and/or Ethyl-ferrocene were injected into the bed from the top, permitting a quasi-lossless precursor operation and a very good control of the deposited metal, and hence of the catalyst structure. Samples could be extracted from the top while CVD was ongoing to obtain time-resolved data. The catalytic activity was determined through CO oxidation. The Fe-Pt mixing ratio was then varied for the most active deposition sequence, in order to identify an activity optimum generated by the minimum amount of Pt catalyst. When compared to pure Pt/Al2O3, the optimum catalyst consistently showed superior performance even after thermal stress.
      Citation: Coatings
      PubDate: 2018-06-11
      DOI: 10.3390/coatings8060217
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 218: Oxidation Behavior of MoSi2-Coated TZM Alloys
           during Isothermal Exposure at High Temperatures

    • Authors: Kwangsu Choi, Young Joo Kim, Min Kyu Kim, Sangyeob Lee, Seong Lee, Joon Sik Park
      First page: 218
      Abstract: Coating properties and oxidation behaviors of Si pack cementation-coated TZM (Mo-0.5Ti-0.1Zr-0.02C) alloys were investigated in order to understand the stability of the coating layer at high temperatures up to 1350 °C in an ambient atmosphere. After the pack cementation coatings, MoSi2 and Mo5Si3 layers were formed. When MoSi2-coated TZM alloys were oxidized in air at high temperatures, the Si in the outer MoSi2 layer diffused and formed SiO2. Also, due to the diffusion of Si, the MoSi2 layer was transformed into a columnar shaped Mo5Si3 phase. During isothermal oxidation, the Mo5Si3 phase was formed both within the coated MoSi2 layer and between the MoSi2 and the substrate. The coating properties and the oxidation behavior of the Si pack-coated TZM alloys were discussed along with the identification of growth kinetics.
      Citation: Coatings
      PubDate: 2018-06-11
      DOI: 10.3390/coatings8060218
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 219: Thermo-Mechanical Finite Element Modeling of
           the Laser Treatment of Titanium Cold-Sprayed Coatings

    • Authors: Felice Rubino, Antonello Astarita, Pierpaolo Carlone
      First page: 219
      Abstract: This paper implements a thermo-mechanical model to simulate the laser treatment effects on a cold-sprayed titanium coating and aluminum substrate. The thermo-mechanical finite element model considers the transient temperature field due to the laser source and applied boundary conditions, using them as input loads for the subsequent stress-strain analysis. Numerical outcomes highlighted the relevance of thermal gradients and the presence of thermally-induced stress-strain fields responsible for promoting damage in the coating.
      Citation: Coatings
      PubDate: 2018-06-12
      DOI: 10.3390/coatings8060219
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 220: Chromium Carbide Growth by Direct Liquid
           Injection Chemical Vapor Deposition in Long and Narrow Tubes, Experiments,
           Modeling and Simulation

    • Authors: Alexandre Michau, Francis Maury, Frederic Schuster, Ioana Nuta, Yoan Gazal, Rapahel Boichot, Michel Pons
      First page: 220
      Abstract: Chromium carbide layers were deposited using liquid-injection metal-organic chemical vapor deposition inside long (0.3 to 1 m) and narrow (8 to 24 mm in diameter) metallic tubes. The deposition was carried out using a molecular single-source, bis(benzene)chromium (BBC), as representative of the bis(arene)metal family diluted in toluene and injected with N2 as carrier gas. A multicomponent mass transport model for the simulation of the coupled fluid flow, heat transfer and chemistry was built. The kinetic mechanism of the growth of CrCx films was developed with the help of large-scale experiments to study the depletion of the precursors along the inner wall of the tube. The model fits well in the 400–550 °C temperature range and in the 1.3 × 102 to 7 × 103 Pa pressure range. The pressure is shown to have a pronounced effect on the deposition rate and thickness uniformity of the resulting coating. Below 525 °C the structure, composition and morphology of the films are not affected by changes of total pressure or deposition temperature. The coatings are amorphous and their Cr:C ratio is about 2:1, i.e., intermediate between Cr7C3 and Cr3C2. The model was applied to the design of a long reactor (1 m), with a double injection successively and alternatively undertaken at each end to ensure the best uniformity with sufficient thickness. This innovative concept can be used to optimize industrial deposition processes inside long and narrow tubes and channels.
      Citation: Coatings
      PubDate: 2018-06-13
      DOI: 10.3390/coatings8060220
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 221: Surface Treatment of Bacterial Cellulose in
           Mild, Eco-Friendly Conditions

    • Authors: Adriana Nicoleta Frone, Denis Mihaela Panaitescu, Ioana Chiulan, Cristian Andi Nicolae, Angela Casarica, Augusta Raluca Gabor, Roxana Trusca, Celina Maria Damian, Violeta Purcar, Elvira Alexandrescu, Paul Octavian Stanescu
      First page: 221
      Abstract: Bacterial cellulose (BC) with increased hydrophobicity is required for several applications including packaging. Surface functionalization of BC may provide good resistance to moisture, increased barrier properties or improved compatibility to polymer matrices. For this purpose, chemical grafting of BC in mild, eco-friendly conditions was carried out using different agents. BC membranes were surface functionalized with vinyl-triethoxy silane (VS) or 3-aminopropyl triethoxysilane (APS), by acylation and acrylation. The efficiency of the surface treatments was highlighted by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, by contact angle measurements and by dynamic mechanical analysis. The morphological investigation by atomic force microscopy and scanning electron microscopy revealed an increased compactness for surface functionalized BC, which correlated well with the different increase of the contact angle. BC treated with APS and VS showed more than a twofold increase in contact angle value. Similarly, the crystallinity degree was reduced to 69.6% and 72.9% after APS and VS treatments as compared with 84.1% for untreated BC, confirming the grafting reaction and the decrease in hydrogen bonding. All the applied treatments delayed the degradation of BC. However, the highest increase in thermal stability was observed for silanes treated membranes. Effective, eco-friendly methods for improving the surface hydrophobicity of bacterial cellulose for food packaging were proposed in this study.
      Citation: Coatings
      PubDate: 2018-06-14
      DOI: 10.3390/coatings8060221
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 222: Stainless Steel Surface Coating with
           Nanocrystalline Ag Film by Plasma Electrolysis Technology

    • Authors: Ah-Der Lin, Chi-Liang Kung, You-Qing Cao, Chao-Ming Hsu, Cheng-Yi Chen
      First page: 222
      Abstract: This paper describes the use of a plasma electrolysis technique to apply a nanosilver coating to the surface of stainless steel to achieve hydrophobic properties. We propose an experimental reaction system, which includes stainless steel 316 as the two electrodes and an aqueous solution of potassium nitrate (KNO3), silver nitrate (AgNO3), and ammonium hydroxide (NH4OH) as the electrolyte. Better results with a stainless steel surface coated by nanocrystalline Ag film are obtained using optimal parameters chosen through one-factor-at-a-time experiments. The main parameters consist of electrode distance, KNO3 concentration, and AgNO3 concentration. The experiment focuses on analyzing the impact of the plasma electrolysis technique on processing time. Variations in KNO3 concentration show that 3 wt.% yields the worst result because it causes an uneven surface, whereas 5 wt.% gives excellent results because it creates an even, porous surface and the highest contact angle. An AgNO3 concentration of 0.03 wt.% yields the best contact angle. With the same processing time, silver sediment increases as the KNO3 concentration increases. With respect to variation in electrode distance, we find that when the distance is set at 20 mm, the contact angle exceeds 100° and results in hydrophobic properties on the specimen surface, while other distances yield a contact angle below 80°, resulting in hydrophilic surfaces. The SEM (scanning electron microscope) results show that the surface of the specimen is full of crater-like cavities that directly affect the contact angle. In this experiment, the contact angle yielding optimum hydrophobic properties is 134° ± 10°. Finally, using distribution patterns obtained by elemental analysis, the experimental results lead to an evenly distributed silver coating on the surface of specimens subjected to plasma electrolysis treatment. The study confirms that plasma electrolysis can be used to coat nanosilver onto stainless steel 316.
      Citation: Coatings
      PubDate: 2018-06-17
      DOI: 10.3390/coatings8060222
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 223: Tribooxidation as a Way to Improve the Wear
           Resistance of Cutting Tools

    • Authors: Dmitry Wainstein, Anatoly Kovalev
      First page: 223
      Abstract: This paper generalizes the results of our research, which was aimed at the development of adaptive cutting tool coatings for high speed dry cutting, from the inception of the idea to complex multilayer coatings for processing tough metals. Typically, the streams of external energy and matter during high speed cutting are causing damage to the tool materials and to the hard, protective coatings through multiple mechanical and chemical processes including oxidation, however these oxidation processes could be used to improve the tools’ lifetime. The structure and the phase transformations on the wear surface in the nanostructured single layer and nanolaminated multilayer PVD coatings were investigated by a set of electron spectroscopy methods. The dynamics of the secondary phase formation on the various stages of tool life is demonstrated. The obtained results show that the enhancement of non-equilibrium processes during friction leads to a dominating formation of protective triboceramics on a base of sapphire-like, tungsten, and niobium polyvalent oxides with a structure which decisively improves the wear performance. The mechanisms of the formation of non-equilibrium protective oxides at high speed dry cutting and the non-equilibrium thermodynamics approaches for the tribooxidation description are discussed. Polyvalent metals and multilayer coatings provide a wider set of protective oxide nanofilms.
      Citation: Coatings
      PubDate: 2018-06-18
      DOI: 10.3390/coatings8060223
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 224: The Potential of Functionalized Ceramic
           Particles in Coatings for Improved Scratch Resistance

    • Authors: Caterina Lesaint Rusu, Malin Brodin, Tor Inge Hausvik, Leif Kåre Hindersland, Gary Chinga-Carrasco, Mari-Ann Einarsrud, Hilde Lea Lein
      First page: 224
      Abstract: The top layer of a typical high pressure floor laminate (HPL) consists of a melamine formaldehyde (MF) impregnated special wear layer (overlay) with alumina particles. This top layer plays a crucial role in determining the mechanical properties of the laminate. For HPLs, scratch resistance and scratch visibility are particularly important properties. This study aimed to improve the mechanical properties, particularly the scratch resistance, by adjusting the composition of the overlay. Laminates containing alumina particles were prepared and tested. These alumina particles were additionally functionalized with a silane coupling agent to ensure better adhesion between the particles and the resin. The functionalized particles led to enhanced scratch resistance of the laminates as well as improved dispersion of the particles within the resin. Micro scratch testing revealed that by using functionalized particles, the scratch surface damage was reduced and the recovery characteristics of the surface layer were improved. Higher scratch resistance and scratch hardness were thus obtained, along with a reduced scratch visibility.
      Citation: Coatings
      PubDate: 2018-06-19
      DOI: 10.3390/coatings8060224
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 225: Interdiffusion at Room Temperature in
           Cu-Ni(Fe) Nanolaminates

    • Authors: Alan F. Jankowski
      First page: 225
      Abstract: The decomposition of a one-dimensional composition wave in Cu-Ni(Fe) nanolaminate structures is quantified using X-ray diffraction to assess kinetics of the interdiffusion process for samples aged at room temperature for 30 years. Definitive evidence for growth to the composition modulation within the chemical spinodal is found through measurement of a negative interdiffusivity for each of sixteen different nanolaminate samples over a composition wavelength range of 2.1–10.6 nm. A diffusivity value Ď of 1.77 × 10−24 cm2·s−1 is determined for the Cu-Ni(Fe) alloy system, perhaps the first such measurement at a ratio of melt temperature to test temperature that is greater than 5. The anomalously high diffusivity value with respect to bulk diffusion is attributed to the nanolaminate structure that features paths for short-circuit diffusion through interlayer grain boundaries.
      Citation: Coatings
      PubDate: 2018-06-20
      DOI: 10.3390/coatings8060225
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 226: ANN Laser Hardening Quality Modeling Using
           Geometrical and Punctual Characterizing Approaches

    • Authors: Ilyes Maamri, Noureddine Barka, Abderrazak El Ouafi
      First page: 226
      Abstract: Maximum hardness and hardened depth are the responses of interest in relation to the laser hardening process. These values define heat treatment quality and have a direct impact on mechanical performance. This paper aims to develop models capable of predicting the shape of the hardness profile depending on laser process parameters for controlling laser hardening quality (LHQ), or rather the response values. An experimental study was conducted to highlight hardened profile sensitivity to process input parameters such as laser power (PL), beam scanning speed (VS) and initial hardness in the core (HC). LHQ modeling was conducted by modeling attributes extracted from the hardness profile curve using two effective techniques based on the punctual and geometrical approaches. The process parameters with the most influence on the responses were laser power, beam scanning speed and initial hardness in the core. The obtained results demonstrate that the geometrical approach is more accurate and credible than the punctual approach according to performance assessment criteria.
      Citation: Coatings
      PubDate: 2018-06-20
      DOI: 10.3390/coatings8060226
      Issue No: Vol. 8, No. 6 (2018)
       
  • Coatings, Vol. 8, Pages 152: Starch-Based Coatings for Preservation of
           Fruits and Vegetables

    • Authors: Mayra Sapper, Amparo Chiralt
      First page: 152
      Abstract: Considerable research has focused on the control of the physiological activity of fruits and vegetables in postharvest conditions as well as microbial decay. The use of edible coatings (ECs) carrying active compounds (e.g., antimicrobials) represents an alternative preservation technology since they can modify the internal gas composition by creating a modified atmosphere through the regulation of the gas exchange (oxygen, carbon dioxide, volatiles) while also limiting water transfer. Of the edible polymers able to form coating films, starch exhibits several advantages, such as its ready availability, low cost and good filmogenic capacity, forming colourless and tasteless films with high oxygen barrier capacity. Nevertheless, starch films are highly water sensitive and exhibit limited water vapour barrier properties and mechanical resistance. Different compounds, such as plasticizers, surfactants, lipids or other polymers, have been incorporated to improve the functional properties of starch-based films/coatings. This paper reviews the starch-based ECs used to preserve the main properties of fruits and vegetables in postharvest conditions as well as the different factors affecting the coating efficiency, such as surface properties or incorporation of antifungal compounds. The great variability in the plant products requires specific studies to optimize the formulation of coating forming products.
      Citation: Coatings
      PubDate: 2018-04-24
      DOI: 10.3390/coatings8050152
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 153: Fouling Release Coatings Based on
           Polydimethylsiloxane with the Incorporation of Phenylmethylsilicone Oil

    • Authors: Miao Ba, Zhanping Zhang, Yuhong Qi
      First page: 153
      Abstract: In this study, phenylmethylsilicone oil (PSO) with different viscosity was used for research in fouling release coatings based on polydimethylsiloxane (PDMS). The surface properties and mechanical properties of the coatings were investigated, while the leaching behavior of PSO from the coatings was studied. Subsequently, the antifouling performance of the coatings was investigated by the benthic diatom adhesion test. The results showed that the coatings with high-viscosity PSO exhibited high levels of hydrophobicity and PSO leaching, while the high PSO content significantly decreased the elastic modulus of the coatings and prolonged the release time of PSO. The antifouling results indicated that the incorporation of PSO into coatings enhanced the antifouling performance of the coating by improving the coating hydrophobicity and decreasing the coating elastic modulus, while the leaching of PSO from the coatings improved the fouling removal rate of the coating. This suggests a double enhancement effect on the antifouling performance of fouling release coatings based on PDMS with PSO incorporated.
      Citation: Coatings
      PubDate: 2018-04-24
      DOI: 10.3390/coatings8050153
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 154: Raman Microscopy for Classification and
           Chemical Surface Mapping of Barrier Coatings on Paper with Oil-Filled
           Organic Nanoparticles

    • Authors: Pieter Samyn
      First page: 154
      Abstract: The creation of functional papers requires a specific deposition of chemical moieties at the surface. In particular, water-repellent barrier coatings can be formed by the deposition of (poly(styrene-co-maleimide) nanoparticles filled with different vegetable oils. The analysis of coated paper surfaces by dispersive Raman spectroscopy allows for statistical classification of different coating types and chemical mapping of the lateral surface distribution of the coating components. The Raman spectra were used to quantify the amount of free oil and imide content. The partial least squares model with three principal components (PC) could differentiate between the type of oil (degree of saturation in PC-1), coating thickness (cellulose bands of paper substrate in PC-2), and organic coating phase (styrene, imide in PC-3). The chemical surface maps with average intensities indicate coating inhomogeneities for thin coatings located near the organic coating components, while the presence of free oil acts as a natural binder in between the organic phase and provides a more homogeneous coating. Depending on the type of oil, a higher amount of free oil coincides with lower imide content at the surface. The surface coverage of polyunsaturated oils overlaps relatively well with the areas of organic coating components, as the oil is largely encapsulated. The surface coverage for mono- and unsaturated oils is rather complementary to the organic phase as there are larger amounts of free oil. The latter is confirmed by single wavenumber maps and image processing constructing composite chemical surface maps.
      Citation: Coatings
      PubDate: 2018-04-24
      DOI: 10.3390/coatings8050154
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 155: Anti-Corrosion Characteristics of
           Electrodeposited Self-Doped Polyaniline Films on Mild Steel in Low Acidity
           

    • Authors: Jhen-Wei Wu, Tzong-Liu Wang, Wen-Churng Lin, Hung-Yin Lin, Mei-Hwa Lee, Chien-Hsin Yang
      First page: 155
      Abstract: Without the addition of inorganic acids, 2,5-Diaminobenzenesulfonic acid (DABSA) molecules form an acid environment, and are then electrochemically copolymerized with AN monomers to generate a self-doped polyaniline (SPAN) film on mild steel substrates. These SPAN deposition films are employed to test the protection efficiency for mild steel in a corrosion environment of HCl and NaCl, respectively. Electrochemical impedance spectroscopy (EIS) and polarization were used to determine the charge transfer resistance (Rct) and corrosion current (Icorr), respectively. The above two parameters Rct and Icorr are combined to evaluate the protection efficiency of SPAN film on mild steel. Experimental results show that the SPAN thin film with the AN/DABSA ratio of 8.8 has the optimal corrosion resistance in 1 M HCl and 1 M NaCl aqueous solutions, respectively.
      Citation: Coatings
      PubDate: 2018-04-25
      DOI: 10.3390/coatings8050155
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 156: Process and Formulation Strategies to Improve
           Adhesion of Nanoparticulate Coatings on Stainless Steel

    • Authors: Jutta Hesselbach, Ann-Christin Böttcher, Ingo Kampen, Georg Garnweitner, Carsten Schilde, Arno Kwade
      First page: 156
      Abstract: The use of ceramic nanoparticles in coatings can significantly improve their mechanical properties such as hardness, adhesion to substrate, and scratch and abrasion resistance. A successful enhancement of these properties depends strongly on the coating formulation used, and the subsequent structure formed during coating. The aim of the present work was to enhance the adhesion between nanoparticulate coatings and stainless-steel substrates. A covalent particle structure was formed and better mechanical properties were achieved by modifying alumina nanoparticles, as well as substrates, with 3-aminopropyltriethoxysilane and by using a formulation consisting of solvent, modified particles, and bisphenol-A-diglycidylether as cross-linking additive. In addition to the adhesion force needed to remove the coating from the substrate, the type of failure (adhesive or cohesive) was characterized to gain a deeper understanding of the structure formation and to identify interdependencies between process, formulation, and coating structure properties. The modification process and the formulation composition were varied to achieve a detailed conception of the relevant correlations. By relating the results to other structural properties, such as the theoretical porosity and thickness, it was possible to understand the formation of the coating structure in more detail.
      Citation: Coatings
      PubDate: 2018-04-26
      DOI: 10.3390/coatings8050156
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 157: Synthesis of Polydimethylsiloxane-Modified
           

    • Authors: Zhan-Ping Zhang, Xiao-Fei Song, Li-Ying Cui, Yu-Hong Qi
      First page: 157
      Abstract: Polydimethylsiloxane (PDMS) could be used to improve the antifouling properties of the fouling release coatings based on polyurethane (PU). A series of polydimethylsiloxane-modified polyurethane coatings were synthesized with various PDMS contents, using the solvent-free method. The effects of PDMS content and seawater immersion on the chain structure and surface morphology were investigated by confocal laser scanning microscopy (CLSM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and X-ray diffraction (XRD). Based on the measurements of contact angles of deionized water and diiodomethane, surface free energies of the coatings were estimated according to the Owens two-liquid method. The PDMS-modified polyurethane exhibited lower surface free energy and a lower glass transition temperature than polyurethane. The presence of PDMS increased the degree of microphase separation, and enhanced the water resistance of the coatings. The optimum amount of PDMS reduced the elastic modulus and increased the ductility of the coating. The presence of PDMS benefited the removal of weakly attached organisms. Panel tests in the Yellow Sea demonstrated the antifouling activity of the PDMS-modified polyurethane.
      Citation: Coatings
      PubDate: 2018-04-26
      DOI: 10.3390/coatings8050157
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 158: Study on Modified Water Glass Used in High
           Temperature Protective Glass Coating for Ti-6Al-4V Titanium Alloy

    • Authors: Shuang Yang, Dali Zhou, Jiabei Zhou, Lei Yang, Qing Fan, Qianqian Yao, Yongqiang Yang
      First page: 158
      Abstract: Sodium silicate water glass was modified with sodium polyacrylate as the binder, the composite slurry used for high-temperature oxidation-resistant coating was prepared by mixing glass powder with good lubrication properties in the binder. The properties of the modified binder and high-temperature oxidation resistance of Ti-6Al-4V titanium alloy coated with composite glass coating were studied by XRD, SEM, EDS, TG-DSC and so on. Results showed that sodium polyacrylate modified water glass could obviously improve the suspension stability of the binder, the pyrolytic carbon in the binder at high temperature could increase the surface tension in the molten glass system, and the composite glass coating could be smooth and dense after heating. Pyrolytic carbon diffused and combined with oxygen in the coating under the heating process to protect the titanium alloy from oxidation. The thickness of the oxide layer was reduced 51% after applying the high-temperature oxidation-resistant coating. The coating also showed a nearly 30% reduction in friction coefficient due to the boundary lubricant regime. During cooling, the coating could be peeled off easily because of the mismatched CTE between the coating and substrate.
      Citation: Coatings
      PubDate: 2018-04-26
      DOI: 10.3390/coatings8050158
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 159: Multi-Walled Carbon Nanotube Coating on
           

    • Authors: Jung-Eun Park, Yong-Seok Jang, Tae-Sung Bae, Min-Ho Lee
      First page: 159
      Abstract: The aim of this study is to enhance the bioactivity of pure titanium using multiple surface treatments for the application of the implant. To form the biofunctional multilayer coating on pure titanium, anodization was conducted to make titanium dioxide nanotubes, then multi-walled carbon nanotubes were coated using a dipping method after an alkali treatment. The surface characteristics at each step were analyzed using a field emission scanning electron microscope and X-ray diffractometer. The effect of the multilayer coating on the biocompatibility was identified using immersion and cytotoxicity tests. Better hydroxyapatite formation was observed on the surface of multilayer-coated pure titanium compared to non-treated pure titanium after immersion in the simulated body fluid. Improvement of biocompatibility by multiple surface treatments was identified through various cytotoxicity tests using osteoblast cells.
      Citation: Coatings
      PubDate: 2018-04-26
      DOI: 10.3390/coatings8050159
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 160: The Functionalization of Nanostructures and
           Their Potential Applications in Edible Coatings

    • Authors: Ricardo M. González-Reza, Claudia I. García-Betanzos, Liliana I. Sánchez-Valdes, David Quintanar-Guerrero, María A. Cornejo-Villegas, María L. Zambrano-Zaragoza
      First page: 160
      Abstract: Nowadays, edible coatings incorporated with nanostructures as systems of controlled release of flavors, colorants and/or antioxidants and antimicrobial substances, also used for thermal and environmental protection of active compounds, represent a gap of opportunity to increase the shelf life of food highly perishable, as well as for the development of new products. These functionalized nanostructures have the benefit of incorporating natural substances obtained from the food industry that are rich in polyphenols, dietary fibers, and antimicrobial substances. In addition, the polymers employed on its preparation, such as polysaccharides, solid lipids and proteins that are low cost and developed through sustainable processes, are friendly to the environment. The objective of this review is to present the materials commonly used in the preparation of nanostructures, the main ingredients with which they can be functionalized and used in the preparation of edible coatings, as well as the advances that these structures have represented when used as controlled release systems, increasing the shelf life and promoting the development of new products that meet the characteristics of functionality for fresh foods ready to eat.
      Citation: Coatings
      PubDate: 2018-04-26
      DOI: 10.3390/coatings8050160
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 161: Synthesis of Core-Shell MgO Alloy
           Nanoparticles for Steelmaking

    • Authors: Jinglong Qu, Shufeng Yang, Hao Guo, Jingshe Li, Tiantian Wang
      First page: 161
      Abstract: In this present study, we aimed to reduce the wetting angle of nanoparticles (NPs) in molten steel and thus, increase their utilization ratio in steel. In order to achieve this, a two-step process was used to synthesize a core-shell AlTi-MgO@C NP structure for steelmaking through a dopamine polymerization process, which used an ammonium persulfate oxidant and high-temperature carbonization. The NP surface characterization was tested by scanning electron microscopy and field emission transmission electron microscopy, while the hydrodynamic NP size was measured by dynamic light scattering. The results showed that a carbon coating that had a thickness of 10 nm covered the NP surface, with the dispersion and stability of the particles in the aqueous solution having improved after the coating. The contact angle of the surface-treated NP was less than that of the uncoated NP in high-temperature molten steel and the corresponding wetting energy was smaller, which indicated improved wettability.
      Citation: Coatings
      PubDate: 2018-04-27
      DOI: 10.3390/coatings8050161
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 162: Mechanical Durability of Engineered
           Superhydrophobic Surfaces for Anti-Corrosion

    • Authors: Divine Sebastian, Chun-Wei Yao, Ian Lian
      First page: 162
      Abstract: Engineered superhydrophobic coating for anti-corrosion applications is a subject of great significance at present. However, the use of superhydrophobic coatings for anti-corrosion applications is hindered by the mechanical durability in many cases. There is a need for an understanding not only of how to fabricate such surfaces, but also of the corrosion resistance and mechanical durability of those coatings. This review discusses recent developments in the mechanical durability of superhydrophobic coatings primarily used for anti-corrosion. First, superhydrophobicity is introduced with an emphasis on different wetting models. After that, this review classifies the nanofabrication methods based on the material and methods of surface functionalization. Furthermore, the testing procedures used for the measurement of corrosion and mechanical durability are presented. Finally, the mechanical durability and anti-corrosion performance of the developed superhydrophobic coatings are discussed.
      Citation: Coatings
      PubDate: 2018-04-27
      DOI: 10.3390/coatings8050162
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 163: Effect of the N/C Ratios of Ammonia Added to
           Process Gas Mixtures on the Morphology and Structure of MPCVD Diamond
           Films

    • Authors: Xuejie Liu, Hongchao Wang, Pengfei Lu, Yuan Ren, Xin Tan, Shiyang Sun, Huiling Jia
      First page: 163
      Abstract: In this study, N-doped diamond films were prepared through microwave plasma chemical vapor deposition with NH3/CH4/H2 gas mixtures. The effects of the ammonia addition to the process gas mixture on the morphology and structure of diamond films were systematically investigated through characterization by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). This work focuses on the ammonia addition to the process gas mixtures in the narrow range of N/C ratios from 0.4% to 1.0%. The results reveal that different N/C ratios can affect the morphology, the preferred crystal orientation, and the sp3/sp2 ratio in the films. When the N/C ratio of the process gas mixture ranges from 0.6% to 1.0%, the XRD and SEM results show that ammonia addition is beneficial for the growth of the (110) faceted grains. When the N/C ratio of the process gas mixture ranges from 0.8% to 1.0%, the XPS and Raman results indicate that the diamond films exhibit a considerable enhancement in the sp3 fraction.
      Citation: Coatings
      PubDate: 2018-04-27
      DOI: 10.3390/coatings8050163
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 164: Dithienylpyrrole- and
           Tris[4-(2-thienyl)phenyl]amine-Containing Copolymers as Promising Anodic
           Layers in High-Contrast Electrochromic Devices

    • Authors: Tzi-Yi Wu, Yuh-Shan Su, Jui-Cheng Chang
      First page: 164
      Abstract: Three dithienylpyrrole- and tris[4-(2-thienyl)phenyl]amine-containing copolymers (P(MPS-co-TTPA), P(MPO-co-TTPA), and P(ANIL-co-TTPA)) were deposited on indium tin oxide (ITO) surfaces using electrochemical polymerization. Spectroelectrochemical characterizations of polymer films revealed that P(MPS-co-TTPA) film was light olive green, greyish-green, bluish grey, and grey in neutral state, intermediate state, oxidized state, and highly oxidized state, respectively, whereas P(MPO-co-TTPA) film was green moss, foliage green, dark greyish-green, and bluish-grey in neutral state, intermediate state, oxidized state, and highly oxidized state, respectively. The ΔTmax of P(MPS-co-TTPA) film at 964 nm, P(MPO-co-TTPA) film at 914 nm, and P(ANIL-co-TTPA) film at 960 nm were 67.2%, 60.7%, and 67.1%, respectively, and the coloration efficiency (η) of P(MPS-co-TTPA) film at 964 nm, P(MPO-co-TTPA) film at 914 nm, and P(ANIL-co-TTPA) film at 960 nm were calculated to be 260.3, 176.6, and 230.8 cm2 C−1, respectively. Dual type complementary colored electrochromic devices (ECDs) were constructed using P(MPS-co-TTPA), P(MPO-co-TTPA), or P(ANIL-co-TTPA) as anodic copolymer layer and PProDOT-Et2 as cathodic polymer layer. P(MPO-co-TTPA)/PProDOT-Et2 ECD revealed high ΔT (55.1%) and high η (766.5 cm2 C−1) at 580 nm. Moreover, P(MPS-co-TTPA)/PProDOT-Et2, P(MPO-co-TTPA)/PProDOT-Et2, and P(ANIL-co-TTPA)/PProDOT-Et2 ECDs showed satisfactory long-term cycling stability and optical memory.
      Citation: Coatings
      PubDate: 2018-04-27
      DOI: 10.3390/coatings8050164
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 165: Carbon-Coated Nickel Nanoparticles: Effect on
           the Magnetic and Electric Properties of Composite Materials

    • Authors: Artyom Plyushch, Jan Macutkevič, Jūras Banys, Polina Kuzhir, Nikolay Kalanda, Alexander Petrov, Clara Silvestre, Mikhail A. Uimin, Anatoly Ye. Yermakov, Olga Shenderova
      First page: 165
      Abstract: Nickel nanoparticles coated with few layers of carbon have been embedded into the polydimethylsiloxane (PDMS) matrix in concentrations up to 11 vol %. Dielectric and magnetic properties of composite materials have been studied in wide frequency (20 Hz–1 MHz) and temperature (130–430 K) ranges. It was demonstrated that the temperature behavior of dielectric properties is determined by glass transitions in the PDSM matrix below 200 K and the Maxwell–Wagner relaxation above room temperature. The possibility of using fabricated composites on the basis of the PDMS matrix for producing a wide range of passive electromagnetic components, such as frequency-selective filters, wide-band detectors/sensors of a bolometric type, and even electromagnetic “black holes” is also discussed.
      Citation: Coatings
      PubDate: 2018-04-27
      DOI: 10.3390/coatings8050165
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 166: Gold Catalyst-Assisted Metal Organic Chemical
           Vapor Deposition of Bi-Te-Ni-Cu-Au Complex Thermoelectric Materials on
           Anodic Aluminum Oxide Nanoporous Template

    • Authors: Yong Gan, Zhen Yu, Jeremy Gan, Wanli Cheng, Mingheng Li
      First page: 166
      Abstract: Complex materials have unique thermal and electron transport properties. In this work, a novel catalyst-assisted metal organic chemical vapor deposition approach was employed to make Bi-Te-Ni-Cu-Au complex materials on an anodic aluminum oxide nanoporous substrate. Nickel acetate, copper nitrate, bismuth acetate, and tellurium (IV) chloride dissolved in N,N-dimethylformamide (DMF) were used as the metal sources for Ni, Bi, Cu, and Te, respectively. Hydrogen was used as the carrier gas. The anodic aluminum oxide substrate sputter-coated on a thin gold coating and was kept at 500 °C in a quartz tube in the reaction chamber. The chemical vapor deposition time was two hours. Scanning electron microscopy was used to reveal the morphology of the deposited materials. Due to metal catalyst assisted growth, the Bi-Te-Ni-Cu-Au materials were self-assembled into islands distributed fairly uniformly on the substrate. The mechanism for the morphological development of the materials was investigated. It was found that the Au nanoparticles facilitated the formation of the complex Bi-Te-Al-Ni-Cu materials. The prepared nanostructure has the highest absolute Seekbeck coefficient value of 260 µV/K, which is more than twice the value obtained from the bulk material.
      Citation: Coatings
      PubDate: 2018-04-27
      DOI: 10.3390/coatings8050166
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 167: Analysis of Sn Concentration Effect on
           Morphological, Optical, Electrical and Photonic Properties of Spray-Coated
           Sn-Doped CdO Thin Films

    • Authors: A. Kathalingam, K. Kesavan, Abu ul Hassan Sarwar Rana, Joonhyeon Jeon, Hyun-Seok Kim
      First page: 167
      Abstract: Tin-doped cadmium oxide (Sn:CdO) transparent thin films with different Sn concentrations were deposited on glass and p-silicon substrates by the chemical spray method at 250 °C. Different concentrations of stannic chloride were used to prepare Sn:CdO thin films. The prepared doped and un-doped CdO films were subjected to X-ray diffraction (XRD), scanning electron microscopy and atomic force microscopy, optical absorption, and electrical analyses to characterize their structural, morphological, optical, and electrical properties, respectively. XRD analysis demonstrated the growth of polycrystalline and cubic CdO with preferential orientation along the (111) plane. Sn-doping shifted the XRD peaks slightly towards a higher Bragg angle and increased the band gap of CdO thin films. Variation in doping concentration also affected the morphology of the films. Optimum Sn-doping increased the electrical conductivity of CdO thin films. Furthermore, to the best of our knowledge, the photoresponse analyses of the fabricated un-doped and doped n-CdO/p-Si heterostructures were performed for the first time in this study.
      Citation: Coatings
      PubDate: 2018-04-27
      DOI: 10.3390/coatings8050167
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 168: The Influence of Oxygen Flow Ratio on the
           Optoelectronic Properties of p-Type Ni1−xO Films Deposited by Ion Beam
           Assisted Sputtering

    • Authors: Hui Sun, Sheng-Chi Chen, Wen-Chi Peng, Chao-Kuang Wen, Xin Wang, Tung-Han Chuang
      First page: 168
      Abstract: In this work, p-type non-stoichiometric Ni1−xO thin films were deposited by oxygen ion beam assisted RF sputtering on glass substrates. The influence of the oxygen flow ratio (0–100%) on the films’ optoelectronic properties was investigated. In our experimental conditions, all the films are crystallized in the cubic NiO phase. However, their crystallinity and mean grain size decreases with increasing oxygen flow ratios. Meanwhile, the films’ conductivity improves from 9.1 to 25.4 S·cm−1. This is due to the fact that the nickel vacancies along with hole carriers can be introduced into NiO films when they are deposited under higher oxygen flow ratio conditions. Thus, the O-rich environment is beneficial in enhancing the films’ carrier concentrations. In addition, with an increasing oxygen flow ratio, the film’s transmittance degrades. The direct optical band gap of Ni1−xO films declines slightly from 3.99 to 3.95 eV, with the oxygen flow ratio increasing from 0% to 100%.
      Citation: Coatings
      PubDate: 2018-04-30
      DOI: 10.3390/coatings8050168
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 169: The Gain of Low Thermal Expansivity via Phase
           Transition in Electroformed Invar

    • Authors: Yong Bum Park, In Gyeong Kim
      First page: 169
      Abstract: In the organic light-emitting diode display industry, Invar exhibits anomalously low thermal expansivity and is, therefore, used as a material for fine metal masks, which are necessary components for the evaporation process of diode materials. We present an electroforming method for fabricating Fe-Ni alloys with a coefficient of thermal expansion lower than that of conventional Invar. The principle of controlling the thermal expansivity of electroformed Fe-Ni alloys is clarified in terms of the behavior of the phases constituting them. The cause of the Invar anomalies, which has not yet been fully elucidated, is explained by combining the Weiss model based on the electron configurations of Fe atoms and a model that we propose based on atom configurations.
      Citation: Coatings
      PubDate: 2018-05-02
      DOI: 10.3390/coatings8050169
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 170: New Consolidant-Hydrophobic Treatment by
           Combining SiO2 Composite and Fluorinated Alkoxysilane: Application on
           Decayed Biocalcareous Stone from an 18th Century Cathedral

    • Authors: Dario S. Facio, Jose A. Ordoñez, M. L. Almoraima Gil, Luis A. M. Carrascosa, Maria J. Mosquera
      First page: 170
      Abstract: An effective procedure has been developed to consolidate and hydrophobize decayed monumental stones by a simple sol-gel process. The sol contains silica oligomer, silica nanoparticles and a surfactant, preventing gel cracking. The effectiveness of the process on biocalcareous stone samples from an 18th century cathedral has been evaluated, and it was found that the gel creates effective linking bridges between mineral grains of the stone. Silica nanoparticles produced a significant increase in the mechanical resistance and cohesion of the stone. The application of an additional fluorinated oligomer onto the consolidated stone gave rise to a surface with lasting hydrophobicity, preventing water absorption.
      Citation: Coatings
      PubDate: 2018-05-02
      DOI: 10.3390/coatings8050170
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 171: Approaches for Detecting Madder Lake in
           Multi-Layered Coating Systems of Historical Bowed String Instruments

    • Authors: Giacomo Fiocco, Tommaso Rovetta, Monica Gulmini, Anna Piccirillo, Claudio Canevari, Maurizio Licchelli, Marco Malagodi
      First page: 171
      Abstract: Musical instrument coatings are generally made by multi-layered systems of organic and inorganic materials, applied on the wood substrate by the violin makers during the finishing process. This coating has paramount relevance for several aspects: protection from sweat and dirt, increase of specific acoustic features, and especially aesthetic effects. In fact, the colour of historical bowed string instruments represents a very peculiar characteristic of each workshop. Among the various colourants, lakes are the most challenging to detect because of their sensibility to the alteration processes. In this work, non-invasive and micro-invasive procedures were applied to a set of mock-ups mimicking historical coatings systems prior and after artificial ageing, in order to highlight the overall information that can be recovered for the detection of madder lake in historical bowed instruments. A set of techniques, including colourimetry, visible and UV-light imaging, stereomicroscopy, Fibre Optics Diffuse Reflectance spectroscopy (FORS), X-ray Fluorescence spectroscopy (XRF), Scanning Electron Microscopy coupled with Energy-Dispersive X-ray microprobe (SEM-EDX), and Fourier-Transform Infrared spectroscopy (FTIR) were used in order to evaluate the pros and cons in the detection of organic and inorganic component of madder lake at low concentration levels.
      Citation: Coatings
      PubDate: 2018-05-03
      DOI: 10.3390/coatings8050171
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 172: HFCVD Diamond-Coated Mechanical Seals

    • Authors: Raul Simões, Bruno Martins, José Santos, Victor Neto
      First page: 172
      Abstract: A mechanical seal promotes the connection between systems or mechanisms, preventing the escape of fluids to the exterior. Nonetheless, due to extreme working conditions, premature failure can occur. Diamond, due to its excellent properties, is heralded as an excellent choice to cover the surface of these devices and extend their lifetime. Therefore, the main objective of this work was to deposit diamond films over mechanical seals and test the coated seals on a water pump, under real working conditions. The coatings were created by hot filament chemical vapor deposition (HFCVD) and two consecutive layers of micro- and nanocrystalline diamond were deposited. One of the main difficulties is the attainment of a good adhesion between the diamond films and the mechanical seal material (WC-Co). Nucleation, deposition conditions, and pre-treatments were studied to enhance the coating. Superficial wear or delamination of the film was investigated using SEM and Raman characterization techniques, in order to draw conclusions about the feasibility of these coatings in the WC-Co mechanical seals with the purpose of increasing their performance and life time. The results obtained gave a good indication about the feasibility of this process and the deposition conditions used, with the mechanical seals showing no wear and no film delamination after a real work environment test.
      Citation: Coatings
      PubDate: 2018-05-03
      DOI: 10.3390/coatings8050172
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 173: Superhydrophobic Bilayer Coating Based on
           Annealed Electrospun Ultrathin Poly(ε-caprolactone) Fibers and
           Electrosprayed Nanostructured Silica Microparticles for Easy Emptying
           Packaging Applications

    • Authors: Juliana Lasprilla-Botero, Sergio Torres-Giner, Maria Pardo-Figuerez, Mónica Álvarez-Láinez, Jose M. Lagaron
      First page: 173
      Abstract: A coating rendering superhydrophobic properties to low-density polyethylene (LDPE) films used in packaging applications was herein generated by means of the electrohydrodynamic processing (EHDP) technique. To this end, electrospun ultrathin poly(ε-caprolactone) (PCL) fibers, followed by electrosprayed nanostructured silica (SiO2) microparticles, were deposited on top of the LDPE film. Various electrospinning and electrospraying times were tested and optimized followed by a thermal post-treatment to provide physical adhesion between the bilayer coating and the LDPE substrate. The morphology, hydrophobicity, permeance to limonene, and thermal stability of the resultant nanostructured coatings were characterized. It was observed that by controlling both the deposition time of the electrospun ultrathin PCL fibers and the electrosprayed SiO2 microparticles, as well as the conditions of the thermal post-treatment, effective superhydrophobic coatings were developed onto the LDPE films. The resultant multilayer presented a hierarchical micro/nanostructured surface with an apparent contact angle of 157° and a sliding angle of 8°. The addition of silica reduced, to some extent, the limonene (aroma) barrier, likely due to the increased surface-to-volume ratio, which allowed permeant sorption to occur but improved the thermal stability of the LDPE/PCL film. As a result, the developed multilayer system of LDPE/PCL/SiO2 has significant potential for use in easy-to-empty packaging applications of high water activity products.
      Citation: Coatings
      PubDate: 2018-05-03
      DOI: 10.3390/coatings8050173
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 174: Study of Near-Cup Droplet Breakup of an
           Automotive Electrostatic Rotary Bell (ESRB) Atomizer Using High-Speed
           Shadowgraph Imaging

    • Authors: Jacob E. Wilson, Stephen W. Grib, Adnan Darwish Ahmad, Michael W. Renfro, Scott A. Adams, Ahmad A. Salaimeh
      First page: 174
      Abstract: Electrostatic Rotary bell (ESRB) atomizers are used as the dominant means of paint application by the automotive industry. They utilize the high rotational speed of a cup to induce primary atomization of a liquid along with shaping air to provide secondary atomization and transport. In order to better understand the fluid breakup mechanisms involved in this process, high-speed shadowgraph imaging was used to visualize the edge of a serrated rotary bell at speeds varying between 5000 and 12,000 RPM and with a water flow rate of 250 ccm. A multi-step image processing algorithm was developed to differentiate between ligaments and droplets during the primary atomization process. The results from this experiment showed that higher bell speeds resulted in a 26.8% reduction in ligament and 22.3% reduction in droplet Sauter Mean Diameters (SMD). Additionally, the ligament (ranging from 40 to 400 μm) diameters formed bimodal distributions, while the droplet (ranging from 40 to 300 μm) diameters formed a normal distribution. Velocities were also measured using particle tracking velocimetry, in which size-dependent velocities could then be computed. Droplet velocities were affected more by rotational speed than droplet SMD, while ligaments were affected by other factors than the rotational speed and ligament SMD.
      Citation: Coatings
      PubDate: 2018-05-03
      DOI: 10.3390/coatings8050174
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 175: Kinetic Research on the Curing Reaction of
           Hydroxyl-Terminated Polybutadiene Based Polyurethane Binder System via
           FT-IR Measurements

    • Authors: Jiahu Guo, Tao Chai, Yucun Liu, Jianlan Cui, Hui Ma, Suming Jing, Lunchao Zhong, Shengdong Qin, Guodong Wang, Xiang Ren
      First page: 175
      Abstract: Polyurethane binder systems based on hydroxyl-terminated polybutadiene (HTPB) possess several superior properties such as superior adhesion, high solid-loading capacity, outstanding mechanical performance, etc. They have been widely used in coatings and adhesives as well as in medical and military industries. The cure reaction between hydroxyl-terminated polybutadiene (HTPB) and diisocyanates plays a key role in the properties of final products as well as the adjustment of process parameters. FT-IR spectroscopy is applied to investigate the kinetics of the curing reaction of HTPB and isophorone diisocyanate (IPDI) in the presence of a low toxic and low viscosity catalyst, stannous isooctoate (TECH). The concentrations of the isocyanate groups (NCO) characterized by FT-IR during the cure reaction with respect to time were recorded at different temperatures and at constant stoichiometric ratio Rn[NCO]/n[OH] = 1.0. The kinetic parameters, i.e., activation energy (Ea), pre-exponential factor (A), activation enthalpy (ΔH) and activation entropy (ΔS) were determined. In addition, the curing process and mechanism of the HTPB-IPDI reaction are discussed.
      Citation: Coatings
      PubDate: 2018-05-04
      DOI: 10.3390/coatings8050175
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 176: Laser Cladding of Embedded Sensors for
           Thermal Barrier Coating Applications

    • Authors: Yanli Zhang, Daniel Mack, Georg Mauer, Robert Vaßen
      First page: 176
      Abstract: The accurate real-time monitoring of surface or internal temperatures of thermal barrier coatings (TBCs) in hostile environments presents significant benefits to the efficient and safe operation of gas turbines. A new method for fabricating high-temperature K-type thermocouple sensors on gas turbine engines using coaxial laser cladding technology has been developed. The deposition of the thermocouple sensors was optimized to provide minimal intrusive features to the TBC, which is beneficial for the operational reliability of the protective coatings. Notably, this avoids a melt pool on the TBC surface. Sensors were deposited onto standard yttria-stabilized zirconia (7–8 wt % YSZ) coated substrates; subsequently, they were embedded with second YSZ layers by the Atmospheric Plasma Spray (APS) process. Morphology of cladded thermocouples before and after embedding was optimized in terms of topography and internal homogeneity, respectively. The dimensions of the cladded thermocouple were in the order of 200 microns in thickness and width. The thermal and electrical response of the cladded thermocouple was tested before and after embedding in temperatures ranging from ambient to approximately 450 °C in a furnace. Seebeck coefficients of bared and embedded thermocouples were also calculated correspondingly, and the results were compared to that of a commercial standard K-type thermocouple, which demonstrates that laser cladding is a prospective technology for manufacturing microsensors on the surface of or even embedded into functional coatings.
      Citation: Coatings
      PubDate: 2018-05-04
      DOI: 10.3390/coatings8050176
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 177: Shelf Life Assessment of Fresh Poultry Meat
           Packaged in Novel Bionanocomposite of Chitosan/Montmorillonite
           Incorporated with Ginger Essential Oil

    • Authors: Victor G. L. Souza, João R. A. Pires, Érica T. Vieira, Isabel M. Coelhoso, Maria P. Duarte, Ana L. Fernando
      First page: 177
      Abstract: Active packaging incorporated with natural extracts is a promising technology to extend shelf life of perishable food. Therefore, this study aimed to produce a bionanocomposite based on chitosan reinforced with sodium montmorillonite (MMT) and incorporated with ginger essential oil (GEO). In vitro activity was assessed through migration assay and antimicrobial study against foodborne bacteria. Phenolic compounds were diffused within 48 h of contact, and retained some of their antioxidant activity. Films demonstrated antimicrobial activity against both Gram-positive and -negative bacteria tested. The effect on the shelf life of fresh poultry meat was determined on samples wrapped in the biopolymers and stored under refrigeration for 15 days, through physicochemical and microbiological analyses. Compared to unwrapped poultry meat, samples wrapped in the bionanocomposites showed a reduction in microorganisms count of 1.2–2.6 log CFU/g, maintained color and pH values and thiobarbituric acid reactive substances (TBARS) index increased at a lower rate, extending fresh poultry meat shelf life. The incorporation of GEO enhanced the biopolymer activity, by reducing lipid oxidation and microbiological growth of the poultry meat. In contrast, reinforcement with MMT imprisoned the active compounds in the polymeric chain, hindering its activity. In conclusion, the bionanocomposites tested represent promising substitutes to commercial and unsustainable plastic films.
      Citation: Coatings
      PubDate: 2018-05-05
      DOI: 10.3390/coatings8050177
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 178: An Analysis of Effect of CO2 Laser Treatment
           on Carbon Fibre Fabric

    • Authors: Yu-de Liou, Kam-hong Chau, Chi-yuen Hui, Ju-liang He, Yin-ling Lam, Chi-wai Kan
      First page: 178
      Abstract: The colour of carbon fibre fabric is black which limits its aesthetic properties. CO2 laser has been used for cutting carbon fibres. The impact of CO2 laser treatment to modify the surface of carbon fibre fabric is investigated in this work. Different combinations of laser process parameters, i.e., pixel time (110, 120, 130, 140, 150, 160, 170, 180, 190 and 200 µs, with 10 µs intervals) and resolution (70, 80, 90 and 100 dpi (dots per inch), with 10 dpi intervals), were used for treating carbon fibre fabric surface. Since the laser process is a surface treatment, contact angle measurement was used for evaluating the wetting property imparted after laser processing. The resistivity of the laser-treated carbon fibre fabric was measured to evaluate any effect on the original electrical property of the carbon fibre fabric. Moreover, surface morphology and functionality of laser-treated carbon fibre fabric were assessed by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy-attenuated total internal reflectance (FTIR-ATR), respectively. SEM assessment was to examine the physical change in the carbon fibre surface after laser processing. On the other hand, the FTIR-ATR measurement can help to evaluate the chemical change in the carbon fibre surface after laser processing.
      Citation: Coatings
      PubDate: 2018-05-06
      DOI: 10.3390/coatings8050178
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 179: Effect of Graphene Oxide/ZSM-5 Hybrid on
           Corrosion Resistance of Waterborne Epoxy Coating

    • Authors: Na Wang, Huiying Gao, Jing Zhang, Ping Kang
      First page: 179
      Abstract: In this study, the preparation of modified graphene oxide (GO) synergistic structure (ZSM-5-NH-GO) and the effect of this structure on the corrosion performance of epoxy coatings were investigated. The structural and morphological properties of ZSM-5-NH-GO were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The corrosion performances were studied by electrochemical impedance spectroscopy (EIS) and salt spray tests. The EIS results showed that the corrosion resistance of steel substrate was considerably improved by ZSM-5-NH-GO. The salt spray tests demonstrated that the ZSM-5-NH-GO coating provided strong corrosion performance for steel substrate. The mechanical properties of the epoxy-composite coatings containing ZSM-5-NH-GO were studied by adhesion tests. The above results indicated that the composite coating containing 0.7 wt % ZSM-5-NH-GO composite possessed most excellent anti-corrosion performance compared with other epoxy coatings.
      Citation: Coatings
      PubDate: 2018-05-07
      DOI: 10.3390/coatings8050179
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 180: Fabrication of Poly(o/m-Toluidine)–SiC/Zinc
           Bilayer Coatings and Evaluation of Their Corrosion Resistances

    • Authors: Chuanbo Hu, Ying Li, Jiawei Zhang, Wenlong Huang
      First page: 180
      Abstract: The purpose of this research was to study the structure and corrosion resistance of poly(o/m-toluidine)-SiC/zinc (Zn) bilayer coatings. Poly(o/m-toluidine) films, such as poly(o-toluidine) (POT) and poly(m-toluidine) (PMT), were chemically deposited on the surface of composite SiC/Zn coating using the solution evaporation method. The structures of poly(o/m-toluidine) were characterized by various optic techniques and the electrochemical behavior was studied by cyclic voltammetry (CV). The structures and morphologies of the SiC/Zn coating were detected by Fourier transformation infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy dispersive spectrometer (EDS), and scanning electron microscopy (SEM). Thereafter, the corrosion resistances of electrodeposited and bilayer coatings were investigated in 3.5% NaCl solution by electrochemical corrosion techniques and an accelerated immersion test. The results showed that the outer POT film exhibits a lower corrosion behavior with respect to PMT, which significantly reduces the corrosion rate of SiC/Zn coating and prolongs the service life of the zinc matrix. The conclusion demontrates that the stronger adsorptive POT film ensures the formed POT–SiC/Zn bilayer coatings possess a compact and low-defect surface, which facilitates POT film to develop its excellent barrier and passivation properties against corrosion.
      Citation: Coatings
      PubDate: 2018-05-09
      DOI: 10.3390/coatings8050180
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 181: Bonding Characteristics and Chemical
           

    • Authors: Li-Chun Chang, Yu-Zhe Zheng, Yung-I Chen, Shan-Chun Chang, Bo-Wei Liu
      First page: 181
      Abstract: High-Si-content transition metal nitride coatings, which exhibited an X-ray amorphous phase, were proposed as protective coatings on glass molding dies. In a previous study, the Zr–Si–N coatings with Si contents of 24–30 at.% exhibited the hardness of Si3N4, which was higher than those of the middle-Si-content (19 at.%) coatings. In this study, the bonding characteristics of the constituent elements of Zr–Si–N coatings were evaluated through X-ray photoelectron spectroscopy. Results indicated that the Zr 3d5/2 levels were 179.14–180.22 and 180.75–181.61 eV for the Zr–N bonds in ZrN and Zr3N4 compounds, respectively. Moreover, the percentage of Zr–N bond in the Zr3N4 compound increased with increasing Si content in the Zr–Si–N coatings. The Zr–N bond of Zr3N4 dominated when the Si content was >24 at.%. Therefore, high Si content can stabilize the Zr–N compound in the M3N4 bonding structure. Furthermore, the thermal stability and chemical inertness of Zr–Si–N coatings were evaluated by conducting thermal cycle annealing at 270 °C and 600 °C in a 15-ppm O2–N2 atmosphere. The results indicated that a Zr22Si29N49/Ti/WC assembly was suitable as a protective coating against SiO2–B2O3–BaO-based glass for 450 thermal cycles.
      Citation: Coatings
      PubDate: 2018-05-11
      DOI: 10.3390/coatings8050181
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 182: Electrodeposition of a Pd-Ni/TiO2 Composite
           Coating on 316L SS and Its Corrosion Behavior in Hot Sulfuric Acid
           Solution

    • Authors: Zhiheng Zhang, Junlei Tang, Yingying Wang, Hu Wang, Bernard Normand, Yu Zuo
      First page: 182
      Abstract: Pd-Ni/TiO2 composite coatings were elaborated on 316L stainless steel by an electrodeposition method. The specimens were obtained from an electrolytic bath that contained various contents (5, 10, and 15 g L−1) of nanosized TiO2 particles. X-ray diffraction (XRD) characterization showed that increasing the TiO2 content in the coatings can decrease the crystal grain size. The surface morphology and chemical composition of the composite coatings were modified by the addition of TiO2 particles in the electrolyte, as shown by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) methods, respectively. The TiO2 content also significantly affected the mechanical and electrochemical properties of the Pd-Ni/TiO2 composite coatings. The microhardness of the Pd-Ni/TiO2 composite coatings can be enhanced by increasing the TiO2 content in the coatings. With the addition of 5 g L−1 TiO2 particles to the electrolyte, the deposited Pd-Ni/TiO2 composite coating presented a remarkably increased corrosion resistance when exposed to a sulfuric acid solution at 60 °C compared with that of the Pd-Ni alloy coating. Nevertheless, the further addition of TiO2 particles into the electrolytic bath did not further improve the corrosion resistance of the composite coating.
      Citation: Coatings
      PubDate: 2018-05-11
      DOI: 10.3390/coatings8050182
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 183: Semitransparent Decorative Coatings Based on
           Optical Interference of Metallic and Dielectric Thin Films for High
           Temperature Applications

    • Authors: Enrique Carretero, Rafael Alonso
      First page: 183
      Abstract: This paper introduces a thin film multilayer structure composed of dielectric and metallic layers that allows for a wide range of aesthetic appearances using the phenomenon of optical interference. In addition, this multilayer structure allows the reflection and transmission coefficients to be controlled independently. The application of these decorative coatings to induction stoves is also studied. The aim is to provide an attractive aesthetic appearance for the transparent glass-ceramic, and allow the visualization of blue and white lighting systems. Moreover, degradation of these decorative coatings is studied at high temperatures, so as to ensure that the coating does not change its aesthetic appearance during normal operation of the stove. It has been found to be necessary to use dielectric materials with low diffusion coefficients of oxygen, or not containing oxygen, to prevent oxidation of the metal layers when subjecting the coating to high temperatures.
      Citation: Coatings
      PubDate: 2018-05-11
      DOI: 10.3390/coatings8050183
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 184: Hydrophilic Self-Replenishing Coatings with
           Long-Term Water Stability for Anti-Fouling Applications

    • Authors: Isabel Jiménez-Pardo, Leendert van der Ven, Rolf van Benthem, Gijsbertus de With, A. Esteves
      First page: 184
      Abstract: Hydrophilic coatings have recently emerged as a new approach to avoiding the adhesion of (bio)organisms on surfaces immersed in water. In these coatings the hydrophilic character is crucial for the anti-fouling (AF) performance. However, this property can be rapidly lost due to the inevitable damages which occur at the surface, reducing the long-term effectiveness of the AF functionality. We report hydrophilic polycarbonate-poly(ethylene glycol) methyl ether (mPEG) polyurethane coatings with tunable hydrophilic properties as well as an excellent and long-term stability in water. The coatings exhibit low protein adhesion values and are able to self-replenish their hydrophilicity after damage, due to the existence of a reservoir of hydrophilic dangling chains incorporated in the bulk. The combination of low Tg and sufficient mobility of the mPEG dangling chains (enabled by chains with higher molecular weight) proved to be crucial to ensure autonomous surface hydrophilicity recovery when the coatings were immersed in water. This coatings and design approach offers new possibilities towards high-performance AF coatings with an extended service life-time which can be used in several major applications areas, such as marine and biomedical coatings, with major economic and environmental benefits.
      Citation: Coatings
      PubDate: 2018-05-14
      DOI: 10.3390/coatings8050184
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 185: Corrosion Resistance of Pipeline Steel with
           Damaged Enamel Coating and Cathodic Protection

    • Authors: Liang Fan, Signo Reis, Genda Chen, Michael Koenigstein
      First page: 185
      Abstract: This paper presents the first report on the corrosion resistance of pipeline steel with damaged enamel coating and cathodic protection in 3.5 wt % NaCl solution. In particular, dual cells are set up to separate the solution in contact with the damaged and intact enamel coating areas, to produce a local corrosion resistance measurement for the first time. Enamel-coated steel samples, with two levels of cathodic protection, are tested to investigate their impedance by electrochemical impedance spectroscopy (EIS) and their cathodic current demand by a potentiostatic test. Due to its glass transition temperature, the enamel-coated pipeline can be operated on at temperatures up to 400 °C. The electrochemical tests show that cathodic protection (CP) can decelerate the degradation process of intact coating and delay the electrochemical reactions at the enamel-steel interface. However, CP has little effect on the performance of coating once damaged and can prevent the exposed steel from corrosion around the damaged site, as verified by visual inspections. Scanning electron microscopy (SEM) indicated no delamination at the damaged enamel–steel interface due to their chemical bond.
      Citation: Coatings
      PubDate: 2018-05-14
      DOI: 10.3390/coatings8050185
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 186: Improvement of Aluminium Film Adhesion on
           PMMA Using Pre-Layer and Specific Annealing

    • Authors: Xiuhua Fu, Gong Zhang, Jing Zhang, Kai Guo, Yonggang Pan
      First page: 186
      Abstract: During the electron beam evaporation for deposition of an aluminium film, high-speed electrons decelerate when they bombard the material and part of the electron energy contributes to radiation. Due to the high sensitivity of polymethyl methacrylate (PMMA) to such radiation (in UV), the PMMA surface is degraded. This results in a weak surface of PMMA layer and decreases film adhesion. Based on the film interface adhesion mechanism and the relationship between film structure and stress, this research proposed and investigated a method for producing high quality Al reflective thin film on a PMMA surface with good adhesion. This was done by depositing a pre-layer of 20 nm Al using resistant evaporation to protect the PMMA surface from radiation damage, followed by the deposition of 80 nm Al using e-beam evaporation with ion assisted deposition. Using this method, an average reflectance of 88.6% was achieved in the wavelength range of 400–800 nm. The elastic modulus and hardness were tested by nanoindentation for the calculation of the thermal stress of the film. Adhesion was tested using the pressure strip peeling test and meets the military national standard.
      Citation: Coatings
      PubDate: 2018-05-15
      DOI: 10.3390/coatings8050186
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 187: Influence of Lamellar Interface Morphology on
           Cracking Resistance of Plasma-Sprayed YSZ Coatings

    • Authors: Jibo Huang, Weize Wang, Xiang Lu, Shaowu Liu, Chaoxiong Li
      First page: 187
      Abstract: Splat morphology is an important factor that influences the mechanical properties and durability of thermal barrier coatings (TBCs). In this study, yttria-stabilized zirconia (YSZ) coatings with different lamellar interface morphologies were deposited by atmospheric plasma spraying (APS) using feedstocks with different particle sizes. The influence of lamellar interface roughness on the cracking resistance of the coatings was investigated. Furthermore, the thermal shock and erosion resistance of coatings deposited by two different powders was evaluated. It was found that the particle size of the feedstock powder affects the stacking morphology of the splat that forms the coating. Coatings fabricated from coarse YSZ powders (45–60 μm) show a relatively rough inter-lamellar surface, with a roughness about 3 times greater than those faricated from fine powders (15–25 μm). Coatings prepared with fine powders tend to form large cracks parallel to the substrate direction under indentation, while no cracking phenomena were found in coatings prepared with coarse powders. Due to the higher cracking resistance, coatings prepared with coarse powders show better thermal shock and erosion resistances than those with fine powders. The results of this study provide a reference for the design and optimization of the microstructure of TBCs.
      Citation: Coatings
      PubDate: 2018-05-15
      DOI: 10.3390/coatings8050187
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 188: Effects of Coating Film Parameters on Thermal
           and Stress Distributions of Glass-Based Phosphor-Converted Color Wheels

    • Authors: Ah-Der Lin, Chi-Liang Kung, Sung-Po Hsu, Chao-Ming Hsu, Cheng-Yi Chen
      First page: 188
      Abstract: To protect the environment, the use of mercury tubes has been prohibited in Europe since 2000. As an alternative, phosphor-doped silicone resin wheels have been used to convert blue-ray laser diodes. However, high-temperature photonic decay and cracking on the lens surface significantly degrade transmission. Recent research has explored the possibility of replacing the silicone encapsulant material of the phosphor layer with glass. In this study, the thermal effects of a glass-based phosphor-converted color wheel (GP wheel) and a silicone-based phosphor-converted color wheel (SP wheel) were investigated using various parameters and geometries. A thermal-structural coupling finite element (FE) model of the color wheels was employed to simulate the thermal and stress distributions. To construct the FE model, experiments were conducted and the inverse engineering approach was employed to extract the optical-to-heat conversion coefficient and the heat convection coefficient. In addition, an arc-shaped moving input heat flux was used to simulate a moving laser input and reduce the calculation time of the FE model. Based on the numerical and experimental results, the FE model developed can simulate the steady/transient behavior of the resin and the GP wheel. In addition, the results reveal that thermal failures of the SP wheel are very likely to occur under all parameters employed in this study, whereas the maximum temperature of the GP wheel reaches only approximately 40% of the glass transition temperature. The numerical results indicate that the GP wheel may be useful for overcoming all of these thermal disadvantages in a high-power laser-lit projector.
      Citation: Coatings
      PubDate: 2018-05-17
      DOI: 10.3390/coatings8050188
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 189: Comparing Colorfastness to Light of
           Wood-Staining Fungal Pigments and Commercial Dyes: An Alternative Light
           Test Method for Color Fastness

    • Authors: Eric M. Hinsch, Seri C. Robinson
      First page: 189
      Abstract: Colorfastness to light is an essential quality for textiles exposed to sunlight for a significant length of time. In this study, the colorfastness (specifically to light) of fabrics dyed with wood-staining (spalting) fungal pigments was compared to the colorfastness of commercial dyes. A short-duration immersion dying method without heat was used to minimize both water and energy usage. Both mordanted and unmordanted fabrics were tested and compared for colorfastness. Additionally, a new method of testing for colorfastness to light was developed. Results indicate that the wood-staining fungal pigments demonstrate superior colorfastness to light over commercial dyes when the employed dyeing method is used. Additionally, the colorfastness to light testing method developed using the L-2 Blue Wool Standard and QUV Accelerated Weathering Machine is a viable alternative to current standard colorfastness to light testing methods.
      Citation: Coatings
      PubDate: 2018-05-19
      DOI: 10.3390/coatings8050189
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 190: Stabilized SPEEK Membranes with a High Degree
           of Sulfonation for Enthalpy Heat Exchangers

    • Authors: Riccardo Narducci, Maria Luisa Di Vona, Assunta Marrocchi, Giorgio Baldinelli
      First page: 190
      Abstract: In this investigation, we explored for the first time the use of cross-linked sulfonated poly (ether ether ketone) (SPEEK) membranes in the fabrication of enthalpy heat exchangers. SPEEK is very sensitive to changes in relative humidity, especially when featuring high degrees of sulfonation (DS), though a poor mechanical stability may be observed in the latter case. Cross-linking is crucial in overcoming this issue, and here, we firstly employed the INCA method (ionomer counter-elastic pressure “nc” analysis) to assess the improvements in the mechanical properties. The cross-link was achieved following a simple thermal-assisted process that occurs directly on the performed membranes. After an initial screening, a degree of cross-link = 0.1 was selected as the better compromise between absorption of water vapor and mechanical properties. When implemented in the enthalpy heat exchanger system, these cross-linked SPEEK membranes enabled a high level of sensible heat exchange, as well as a remarkable variation in the mass (water vapor) transfer between the individual air flows. The performances resulted in being better than those for the system based on a benchmark commercially available perfluorinated Nafion membrane.
      Citation: Coatings
      PubDate: 2018-05-19
      DOI: 10.3390/coatings8050190
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 191: Effects of Flow Rates and Density Matching on
           the Integrity of Solid Particles Coated by Water Phase Compound Droplets
           during the Transport Process

    • Authors: Dawei Pan, Meifang Liu, Qiang Chen, Weixing Huang, Bo Li
      First page: 191
      Abstract: To achieve the integrity of solid particles coated by water phase (S/W/O) compound droplets, it is important to investigate the transport process of the compound droplets in the horizontal straight channel. The experimental results show that the integrity is significantly influenced by the flow rates and density difference. The water (W) phase is observed to be peeled off from the surface of the particles (polystyrene (PS) shells), mainly caused by the slip velocity of the W phase and the density mismatching among three phases. During the peeling off process, a relative motion between the solid (S) and W phases initially occurs, causing a decrease of the distance (δ) between them, and then, the PS shell is driven to pass through the W/O interface under the action of drag force and net gravity. It is also found that increasing flow rates of both phases contributes to obtaining integrated compound droplets. A boundary that separates the integrated from damaged compound droplets also exits when the fluid properties are fixed. Above the line of the boundary, compound droplets with integrity are prepared. Moreover, the absolute optimum density matching between the S and W phases is less than 0.003 g/cm3, while that between the W and oil (O) phases is less than 0.005 g/cm3.
      Citation: Coatings
      PubDate: 2018-05-19
      DOI: 10.3390/coatings8050191
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 192: Design and Preparation of a Micro-Pyramid
           Structured Thin Film for Broadband Infrared Antireflection

    • Authors: Shaobo Ge, Weiguo Liu, Shun Zhou, Shijie Li, Xueping Sun, Yuetian Huang, Pengfei Yang, Jin Zhang, Dabin Lin
      First page: 192
      Abstract: A micro-pyramid structured thin film with a broad-band infrared antireflection property is designed and fabricated by using the single-point diamond turning (SPDT) technique and combined with nano-imprint lithography (NIL). A structure with dimensions of 10 μm pitch and 5 μm height is transferred from the copper mold to the silicon nitride optical film by using NIL and proportional inductively-coupled plasma (ICP) etching. Reflectance of the micro-optical surface is reduced below 1.0% over the infrared spectral range (800–2500 nm). A finite-difference-time-domain (FDTD) analysis indicates that this micro-structure can localize photons and enhance the absorption inside the micro-pyramid at long wavelengths. As described above, the micro-pyramid array has been integrated in an optical film successfully. Distinguishing from the traditional micro-optical components, considering the effect of refraction and diffraction, it is a valuable and flexible method to take account of the interference effect of optical film.
      Citation: Coatings
      PubDate: 2018-05-21
      DOI: 10.3390/coatings8050192
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 193: Effect of Annealing Treatment on
           Microstructure and Properties of Cr-Coatings Deposited on AISI 5140 Steel
           by Brush-Plating

    • Authors: Jianjun Hu, Jie Jiang, Hui Li, Xian Yang, Hongbin Xu, Yan Jin, Chaoping Ma, Qingshan Dong, Ning Guo
      First page: 193
      Abstract: Cr-coating was deposited on AISI 5140 steel by electro brush-plating, followed by annealing treatment at different temperatures, from 300 to 1100 °C. The microstructure evolution of the Cr-coating was characterized by backscattered electron imaging (BSEI) and energy dispersive spectrometry (EDS). The results show that the brush-plated sample has a nodular shaped microstructure, which is very stable at 300 °C of annealing. At 500 °C of annealing, the constitution of the microstructure changes from nodules to grains. As the annealing temperature further increases, the grains grow significantly. When the temperature reaches 1100 °C, a Cr-Fe solid-solution layer is formed within the original pure Cr-coatings. With increasing annealing temperature, the number of micro-cracks in the coating increases first and then decreases, reaching a maximum at 500 °C. The hardness and wear-resistance of the coating are improved when the annealing temperature increases to 1100 °C, owing to the decrease of micro-cracks that formed during brush-plating.
      Citation: Coatings
      PubDate: 2018-05-21
      DOI: 10.3390/coatings8050193
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 194: Evolution of Calcareous Deposits and Passive
           Film on 304 Stainless Steel with Cathodic Polarization in Sea Water

    • Authors: Tianxiang Sun, Guosheng Huang, Ping Lv, Likun Xu, Li Ma
      First page: 194
      Abstract: The change of protective current density, the formation and growth of calcareous deposits, and the evolution of passive film on 304 stainless steel (SS) were investigated at different potentials of cathodic polarization in sea water. Potentiostatic polarization, electrochemical impedance spectroscopy (EIS), and surface analysis techniques of scanning electron microscopy (SEM), energy dispersive X-ray (EDX) microanalysis and X-ray diffraction (XRD) were used to characterize the surface conditions. It was found that the protective current density was smaller for keeping polarization at −0.80 V (vs. saturated calomel electrode (SCE), same as below) than that at −0.65 V. The calcareous deposits could not be formed on 304 SS with polarization at −0.50 V while it was well protected. The formation rate, the morphology, and the constituent of the calcareous deposits depended on the applied potential. The resistance of passive film on 304 SS decreased at the first stage and then increased when polarized at −0.80 V and −0.65 V, which was related to the reduction and the repair of passive film. For the stainless steel polarized at −0.50 V, the film resistance increased with polarization time, indicating that the growth of oxide film was promoted.
      Citation: Coatings
      PubDate: 2018-05-21
      DOI: 10.3390/coatings8050194
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 195: Influences of Cr and Co on the Growth of
           Thermally Grown Oxide in Thermal Barrier Coating during High-Temperature
           Exposure

    • Authors: Weifang Zhang, Jingyu Zhang, Hongxun Wang, Weitao Lou, Xiaopeng Liu
      First page: 195
      Abstract: Thermal barrier coating (TBC) is a critical material in the aerospace domain to increase the lifetime of gas turbine components subjected to thermal load. The properties of TBC are strongly related to the growth of thermally grown oxide (TGO) whose main constituent is Al2O3. However, the oxidation of Cr and Co can affect the growth of TGO, which is not studied sufficiently. In this paper, high-temperature exposure at 1000 °C was performed to investigate the effect of Cr and Co oxides on TGO growth. The morphology and composition analysis of the interface between the ceramic top coat and the bond coat (TC/BC) were investigated by using scanning electron microscopy (SEM) and the energy dispersion spectrum (EDS). The thermodynamics and kinetics of oxidation were analyzed. The results indicated that the oxidation kinetics basically followed the sub-parabolic law with exposure time. Additionally, the major factor affecting the formation of oxides was the diffusion rate at the initial stage of exposure, then oxides depended on thermodynamics, and the oxidation was influenced by both of them in the last stage. The major elements to be oxidized were different at different stages. Moreover, the replacement reaction of Cr2O3 and the phase conversion of Al2O3 resulted in thickness variations of the TGO and Al-depleted zone during high-temperature exposure.
      Citation: Coatings
      PubDate: 2018-05-22
      DOI: 10.3390/coatings8050195
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 196: On the Importance of Combined
           Scratch/Acoustic Emission Test Evaluation: SiC and SiCN Thin Films Case
           Study

    • Authors: Jan Tomastik, Radim Ctvrtlik, Martin Drab, Jan Manak
      First page: 196
      Abstract: The scratch test, as probably the most widespread technique for assessment of the adhesive/cohesive properties of a film–substrate system, fully depends on reliable evaluation based on assessment of critical loads for systems’ failures. Traditionally used evaluation methods (depth change record and visual observation) may sometimes give misleading conclusions about the failure dynamics, especially in the case of opaque films. Therefore, there is a need for another independent evaluation technique with the potential to complete the existing approaches. The nondestructive method of acoustic emission, which detects the elastic waves emitted during film cracking and delamination, can be regarded as a convenient candidate for such a role even at nano/micro scale. The strength of the combination of microscopic observation of the residual groove and depth change record with the acoustic emission detection system proved to be a robust and reliable approach in analyzing adhesion/cohesion properties of thin films. The dynamics of the gradual damage taking place during the nano/micro scratch test revealed by the combined approach is presented for SiC and SiCN thin films. Comparison of critical load values clearly reflects the higher ability of the AE approach in detecting the initial material failure compared to the visual observation.
      Citation: Coatings
      PubDate: 2018-05-22
      DOI: 10.3390/coatings8050196
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 197: Antibacterial Functionalization of PVD
           Coatings on Ceramics

    • Authors: Javier Osés, Gonzalo Fuentes, José Palacio, Joseba Esparza, José García, Rafael Rodríguez
      First page: 197
      Abstract: The application of surface treatments that incorporate silver or copper as antibacterial elements has become a common practice for a wide variety of medical devices and materials because of their effective activity against nosocomial infections. Ceramic tiles are choice materials for cladding the floors and walls of operation rooms and other hospital spaces. This study is focused on the deposition of biocide physical vapor deposition (PVD) coatings on glazed ceramic tiles. The objective was to provide antibacterial activity to the surfaces without worsening their mechanical properties. Silver and copper-doped chromium nitride (CrN) and titanium nitride (TiN) coatings were deposited on samples of tiles. A complete characterization was carried out in order to determine the composition and structure of the coatings, as well as their topographical and mechanical properties. The distribution of Ag and Cu within the coating was analyzed using glow discharge optical emission spectrometry (GD-OES) and field emission scanning electron microscope (FE-SEM). Roughness, microhardness, and scratch resistance were measured for all of the combinations of coatings and dopants, as well as their wettability. Finally, tests of antibacterial efficacy against Staphylococcus aureus and Escherichia coli were carried out, showing that all of the doped coatings had pronounced biocide activity.
      Citation: Coatings
      PubDate: 2018-05-22
      DOI: 10.3390/coatings8050197
      Issue No: Vol. 8, No. 5 (2018)
       
  • Coatings, Vol. 8, Pages 128: Thickness-Dependent Bioelectrochemical and
           Energy Applications of Thickness-Controlled Meso-Macroporous
           Antimony-Doped Tin Oxide

    • Authors: Daniel Mieritz, Runli Liang, Haojie Zhang, Anne-Marie Carey, Shaojiang Chen, Alex Volosin, Su Lin, Neal Woodbury, Dong-Kyun Seo
      First page: 128
      Abstract: Coatings of hierarchically meso-macroporous antimony-doped tin oxide (ATO) enable interfacing adsorbed species, such as biomacromolecules, with an electronic circuit. The coating thickness is a limiting factor for the surface coverage of adsorbates, that are electrochemically addressable. To overcome this challenge, a carbon black-based templating method was developed by studying the composition of the template system, and finding the right conditions for self-standing templates, preventing the reaction mixture from flowing out of the mask. The thicknesses of as-fabricated coatings were measured using stylus profilometry to establish a relationship between the mask thickness and the coating thickness. Cyclic voltammetry was performed on coatings with adsorbed cytochrome c to check whether the entire coating thickness was electrochemically addressable. Further, bacterial photosynthetic reaction centers were incorporated into the coatings, and photocurrent with respect to coating thickness was studied. The template mixture required enough of both carbon black and polymer, roughly 7% carbon black and 6% poly(ethylene glycol). Coatings were fabricated with thicknesses approaching 30 µm, and thickness was shown to be controllable up to at least 15 µm. Under the experimental conditions, photocurrent was found to increase linearly with the coating thickness, up to around 12 µm, above which were diminished gains.
      Citation: Coatings
      PubDate: 2018-04-02
      DOI: 10.3390/coatings8040128
      Issue No: Vol. 8, No. 4 (2018)
       
  • Coatings, Vol. 8, Pages 129: Investigation of Element Effect on
           High-Temperature Oxidation of HVOF NiCoCrAlX Coatings

    • Authors: Pimin Zhang, Ru Lin Peng, Xin-Hai Li, Sten Johansson
      First page: 129
      Abstract: MCrAlX (M: Ni or Co or both, X: minor elements) coatings have been used widely to protect hot components in gas turbines against oxidation and heat corrosion at high temperatures. Understanding the influence of the X-elements on oxidation behavior is important in the design of durable MCrAlX coatings. In this study, NiCoCrAlX coatings doped with Y + Ru and Ce, respectively, were deposited on an Inconel-792 substrate using high velocity oxygen fuel (HVOF). The samples were subjected to isothermal oxidation tests in laboratory air at 900, 1000, and 1100 °C and a cyclic oxidation test between 100 and 1100 °C with a 1-h dwell time at 1100 °C. It was observed that the coating with Ce showed a much higher oxidation rate than the coating with Y + Ru under both isothermal and cyclic oxidation tests. In addition, the Y + Ru-doped coating showed significantly lower β phase depletion due to interdiffusion between the coating and the substrate, resulting from the addition of Ru. Simulation results using a moving phase boundary model and an established oxidation-diffusion model showed that Ru stabilized β grains, which reduced β-depletion of the coating due to substrate interdiffusion. This paper, combining experiment and simulation results, presents a comprehensive study of the influence of Ce and Ru on oxidation behavior, including an investigation of the microstructure evolution in the coating surface and the coating-substrate interface influenced by oxidation time.
      Citation: Coatings
      PubDate: 2018-04-03
      DOI: 10.3390/coatings8040129
      Issue No: Vol. 8, No. 4 (2018)
       
  • Coatings, Vol. 8, Pages 130: Realization of Graphene on the Surface of
           Electroless Ni–P Coating for Short-Term Corrosion Prevention

    • Authors: Qin-Ying Wang, Jing Yu, Jiao Xu, Hao-Ming Fang, Shuang Liu, Yi-Rong Tang, Yu-Chen Xi, Shu-Lin Bai
      First page: 130
      Abstract: Graphene was first fabricated on the surface of an electroless Ni–P coating/carbon steel (Ni–P–G) to improve its corrosion resistance. Meanwhile, an electroless Ni–P coating (Ni–P) was heated (Ni–P–H) under the same condition as Ni–P–G for comparison. The morphological results showed that a wavy multilayer graphene was formed on the surface of Ni–P–G. The layer number of the graphene film was 5–10 according to the analysis of Raman spectra and observation by a high-resolution transmission electron microscope. The ID/IG ratio calculated from the Raman spectrum revealed that the graphene growing at the grain of Ni–P–H had larger grain size than that growing at the grain boundary. The electrochemical results showed a higher Rp, a lower CPEdl, and a lower corrosion rate of Ni–P–G than Q235 steel, Ni–P, and Ni–P–H, indicating a higher corrosion resistance. In addition, the surface potential map achieved by a scanning Kelvin probe presented a more positive surface potential of Ni–P–G than Ni–P with the difference being around 375–750 mV, demonstrating a lower corrosion tendency of Ni–P–G.
      Citation: Coatings
      PubDate: 2018-04-04
      DOI: 10.3390/coatings8040130
      Issue No: Vol. 8, No. 4 (2018)
       
  • Coatings, Vol. 8, Pages 131: Recent Advances in Low-Temperature Deposition
           Methods of Transparent, Photocatalytic TiO2 Coatings on Polymers

    • Authors: Jonathan Watté, Matthias Van Zele, Klaartje De Buysser, Isabel Van Driessche
      First page: 131
      Abstract: In this paper, we present an overview as well as current advances in the low-temperature deposition of highly crystalline suspensions of titania nanoparticles on polymers for photocatalytic applications. The presence of preformed titania nanoparticles yields the possibility of producing photocatalytically active coatings at reduced temperatures. Transparent and photocatalytically active TiO2 coatings that degrade organic matter, have been widely applied to bestow self-cleaning properties onto surfaces. This low-temperature deposition method and its transition to polymers would open an entire array of possible self-cleaning applications. During this research, incorporation of a silica buffer layer was applied to improve the compatibility of the inorganic coating on a substrate, such as polymethylmethacrylate (PMMA) and polyphenylsulphone (PPSU). The photocatalytic activity of the obtained coating was analyzed for its photocatalytic abilities by evaluating the color removal of a dye solution (methylene blue, MB) under UV irradiation and compared with commercial Pilkington Activ® self-cleaning glass. Our results indicate that the titania-coated silica-polymer systems yield a higher photocatalytic activity towards the degradation of organic pollutants. This method proves that the deposition of highly crystalline anatase suspensions on silica buffer layers is a viable method to produce photocatalytic coatings on heat-sensitive substrates.
      Citation: Coatings
      PubDate: 2018-04-04
      DOI: 10.3390/coatings8040131
      Issue No: Vol. 8, No. 4 (2018)
       
  • Coatings, Vol. 8, Pages 132: Enhancement of the Corrosion Resistance of
           304 Stainless Steel by Cr–N and Cr(N,O) Coatings

    • Authors: Mihaela Dinu, Emile S. Massima Mouele, Anca C. Parau, Alina Vladescu, Leslie F. Petrik, Mariana Braic
      First page: 132
      Abstract: Chromium nitride and oxynitride coatings were deposited as monolayers ((Cr–N), Cr(N,O)) and bilayers (Cr–N/Cr(N,O), Cr(N,O)/Cr–N) on 304 steel substrates by reactive cathodic arc method. The coatings were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), surface profilometry, and scratch tester. The anticorrosive properties of the coatings were assessed by electrochemical tests in 0.10 M NaCl + 1.96 M H2O2, carried out at 24 °C. Cr2N, CrN, and Cr(N,O) phases were identified in the coatings by grazing incidence X-ray diffraction (GI-XRD) measurements. The measured adhesion values ranged from 19 N to 35 N, the highest value being obtained for the bilayer with Cr(N,O) on top. Electrochemical tests showed that Cr(N,O) presence in both mono- and bilayered coatings determined the lowest damage in corrosive solution, as compared to the Cr–N coatings. This improvement was ascribed to the more compact structure, lower coatings porosity, and smoother surface.
      Citation: Coatings
      PubDate: 2018-04-05
      DOI: 10.3390/coatings8040132
      Issue No: Vol. 8, No. 4 (2018)
       
  • Coatings, Vol. 8, Pages 133: Chitosan Based Regenerated Cellulose Fibers
           Functionalized with Plasma and Ultrasound

    • Authors: Urška Vrabič Brodnjak, Adolf Jesih, Diana Gregor-Svetec
      First page: 133
      Abstract: The great potential of regenerated cellulose fibers, which offer excellent possibilities as a matrix for the design of bioactive materials, was the lead for our research. We focused on the surface modification of fibers to improve the sorption properties of regenerated cellulose and biocomposite regenerated cellulose/chitosan fibers, which are on the market. The purpose of our investigation was also the modification of regenerated cellulose fibers with the functionalization by chitosan as a means of obtaining similar properties to biocomposite regenerated cellulose/chitosan fibers on the market. Argon gas plasma was used for fiber surface activation and chitosan adsorption. Ultrasound was also used as a treatment procedure for the surface activation of regenerated cellulose fibers and treatment with chitosan. Analyses have shown that ultrasonic energy or plasma change the accessibility of free functional groups, structure and reactivity, especially in regenerated cellulose fibers. Changes that occurred in the morphology and in the structure of fibers were also reflected in their physical and chemical properties. Consequently, moisture content, sorption properties and water retention improved.
      Citation: Coatings
      PubDate: 2018-04-05
      DOI: 10.3390/coatings8040133
      Issue No: Vol. 8, No. 4 (2018)
       
  • Coatings, Vol. 8, Pages 134: Tribological Properties of New Cu-Al/MoS2
           Solid Lubricant Coatings Using Magnetron Sputter Deposition

    • Authors: Ming Cao, Lan Zhao, Libin Wu, Wenquan Wang
      First page: 134
      Abstract: The increasing demands of environmental protection have led to solid lubricant coatings becoming more and more important. A new type of MoS2-based coating co-doped with Cu and Al prepared by magnetron sputtering, including Cu/MoS2 and Cu-Al/MoS2 coatings, for lubrication applications is reported. To this end, the coatings were annealed in an argon atmosphere furnace. The microstructure and the tribological properties of the coatings prior to and following annealing were analyzed using scanning electron microscopy, energy dispersive spectrometry, X-ray diffractometry (XRD) and with a multi-functional tester for material surface properties. The results demonstrated that the friction coefficient of the Cu/MoS2 coating was able to reach as low as 0.07, due to the synergistic lubrication effect of the soft metal Cu with MoS2. However, the wear resistance of the coating was not satisfied. Although the lowest friction coefficient of the Cu-Al/MoS2 coatings was 0.083, the wear resistance was enhanced, which was attributed to the improved the toughness of the coatings due to the introduction of aluminum. The XRD results revealed that the γ2-Cu9Al4 phase was formed in the specimen of Cu-Al/MoS2 coatings. The comprehensive performance of the Cu-Al/MoS2 coatings after annealing was improved in comparison to substrate heating, since the heat-treatment was beneficial for the strengthening of the solid solution of the coatings.
      Citation: Coatings
      PubDate: 2018-04-06
      DOI: 10.3390/coatings8040134
      Issue No: Vol. 8, No. 4 (2018)
       
  • Coatings, Vol. 8, Pages 135: Physicochemical and Biological Activity
           Analysis of Low-Density Polyethylene Substrate Modified by Multi-Layer
           Coatings Based on DLC Structures, Obtained Using RF CVD Method

    • Authors: Karol Kyzioł, Julia Oczkowska, Daniel Kottfer, Marek Klich, Łukasz Kaczmarek, Agnieszka Kyzioł, Zbigniew Grzesik
      First page: 135
      Abstract: In this paper, the surface properties and selected mechanical and biological properties of various multi-layer systems based on diamond-like carbon structure deposited on low-density polyethylene (LDPE) substrate were studied. Plasma etching and layers deposition (incl. DLC, N-DLC, Si-DLC) were carried out using the RF CVD (radio frequency chemical vapor deposition) method. In particular, polyethylene with deposited N-DLC and DLC layers in one process was characterized by a surface hardness ca. seven times (up to ca. 2.3 GPa) higher than the unmodified substrate. Additionally, its surface roughness was determined to be almost two times higher than the respective plasma-untreated polymer. It is noteworthy that plasma-modified LDPE showed no significant cytotoxicity in vitro. Thus, based on the current research results, it is concluded that a multilayer system (based on DLC coatings) obtained using plasma treatment of the LDPE surface can be proposed as a prospective solution for improving mechanical properties while maintaining biocompatibility.
      Citation: Coatings
      PubDate: 2018-04-10
      DOI: 10.3390/coatings8040135
      Issue No: Vol. 8, No. 4 (2018)
       
  • Coatings, Vol. 8, Pages 136: Sharply Reduced Biofilm Formation from
           Cobetia marina and in Black Sea Water on Modified Siloxane Coatings

    • Authors: Danail Akuzov, Lia Franca, Ingo Grunwald, Todorka Vladkova
      First page: 136
      Abstract: Siloxane fouling release coatings are currently the only viable non-toxic commercial alternative to toxic biocide antifouling paints. However, they only partially inhibit biofouling since biofilms remain a major issue. With the aim to improve the bacterial resistance of siloxane coatings modified with non-ionic surfactant (NIS), antioxidant (AO) or both NIS/AO, the ability of PEG-silane co-cross-linker was investigated to reduce Cobetia marina adhesion and multispecies biofilm formation from natural seawater. Surface physical-chemical and physical-mechanical parameters relevant to bio-adhesion were estimated before the testing of the biofilm formation. Slightly reduced biofilm from C. marina and sharply reduced multispecies biofilm, formed in natural sea water, were found on the PEG-silane co-cross-linked coatings without modifying additives. However, both C. marina growth and biofilm formation from natural sea water were sharply reduced on the PEG-silane co-cross-linked coatings containing NIS or AO, even more, no C. marina adhesion was seen on the coating containing NIS and AO simultaneously. Possible explanations of the observed effects are presented in this article. It was concluded that the PEG-silane co-cross-linker, toghether with NIS and AO, can be used as an efficient tool to additionally reduce the bioadhesion of Gram-negative marine bacteria and multispecies biofilm formation on siloxane antifouling coatings.
      Citation: Coatings
      PubDate: 2018-04-11
      DOI: 10.3390/coatings8040136
      Issue No: Vol. 8, No. 4 (2018)
       
  • Coatings, Vol. 8, Pages 137: 2D Materials-Coated Plasmonic Structures for
           SERS Applications

    • Authors: Ming Xia
      First page: 137
      Abstract: Two-dimensional (2D) materials, such as graphene and hexagonal boron nitride, are new kinds of materials that can serve as substrates for surface enhanced Raman spectroscopy (SERS). When combined with traditional metallic plasmonic structures, the hybrid 2D materials/metal SERS platform brings extra benefits, including higher SERS enhancement factors, oxidation protection of the metal surface, and protection of molecules from photo-induced damages. This review paper gives an overview of recent progress in the 2D materials-coated plasmonic structure in SERS application, focusing on the fabrication of the hybrid 2D materials/metal SERS platform and its applications for Raman enhancement.
      Citation: Coatings
      PubDate: 2018-04-12
      DOI: 10.3390/coatings8040137
      Issue No: Vol. 8, No. 4 (2018)
       
  • Coatings, Vol. 8, Pages 138: Lanthanum-Silica Sol-Gel Coatings for
           Protecting Metallic Materials in Museums: Approaches to Copper, Bronze,
           Lead and Steel

    • Authors: Javier Peña-Poza, Fernando Agua, Cristina Gil, María-Ángeles Villegas, Manuel García-Heras
      First page: 138
      Abstract: Museum objects made from metals face the challenge of delaying corrosion in exhibition rooms, showcases and holdings. This study examined some innovative solutions used to protect such items based on sol-gel coatings doped with lanthanum. These coatings were prepared from sols based on TEOS as a precursor. Lanthanum acetate/nitrate was added as a doping agent and corrosion inhibitor. The coatings were deposited upon slabs of copper, bronze, lead and steel, since they are among the most common metals present in museums items. The coatings application was accomplished by immersion-extraction, and the remaining sols were gelled and characterized by Fourier transformed infrared spectroscopy and differential thermal analysis and thermogravimetry. To evaluate the behaviour and resistance of the coatings, tests of accelerated aging were carried out in climatic and Kesternich chambers, as well as under an atmosphere saturated with organic acids and under UV irradiation. The simulated conditions tested were undertaken to approach real conditions inside a conventional museum showcase. The microstructure of the coatings before and after accelerated aging tests was observed through optical and field emission scanning electron microscopies. The results indicated that these coatings can be a useful preventive, conservation avenue to protect copper, bronze and lead items exhibited in museums.
      Citation: Coatings
      PubDate: 2018-04-12
      DOI: 10.3390/coatings8040138
      Issue No: Vol. 8, No. 4 (2018)
       
  • Coatings, Vol. 8, Pages 139: Effect of Reaction Conditions on the Surface
           Modification of Cellulose Nanofibrils with Aminopropyl Triethoxysilane

    • Authors: Eduardo Robles, Levente Csóka, Jalel Labidi
      First page: 139
      Abstract: Nine different surface modifications of cellulose nanofibrils (CNF) with 3-aminopropyl triethoxysilane (ATS) by using three different solvent systems (water, ethanol, and a mixture of both) were investigated. The effect of reaction conditions, such as silane to cellulose ratio and solvent type were evaluated to determine their contribution to the extent of the silane modification. Nanofibril properties were evaluated by infrared spectroscopy, powder X-ray diffraction, surface free energy, thermogravimetry, 13C and 29Si nuclear magnetic resonance, and electronic microscopy. The influence of the solvent in the solvolysis of the silane was reflected in the presence or absence of ethoxy groups in the silane. On the other hand, whereas the surface modification was increased directly proportionally to silane ratio on the reaction, the aggregation of nanofibrils was also increased, which can play a negative role in certain applications. The increment of silane modification also had substantial repercussions on the crystallinity of the nanofibrils by the addition of amorphous components to the crystalline unit; moreover, silane surface modifications enhanced the hydrophobic character of the nanofibrils.
      Citation: Coatings
      PubDate: 2018-04-13
      DOI: 10.3390/coatings8040139
      Issue No: Vol. 8, No. 4 (2018)
       
  • Coatings, Vol. 8, Pages 140: Microstructure Evolution of a Magnesium
           Phosphate Protective Layer on Concrete Structures in a Sulfate Environment
           

    • Authors: Jun Li, Yongsheng Ji, Guodong Huang, Linglei Zhang
      First page: 140
      Abstract: This study investigates the resistance of an uncoated magnesium phosphate cement (MPC) protective layer to sulfate attacks through changes in its compressive strength and appearance. X-ray Diffraction (XRD) and scanning electron microscopy (SEM) microanalyses are conducted on the MPC layer concrete both before and after etching, where changes in the microstructure of the magnesium phosphate protective layer are analyzed during the corrosion process. In addition, this study also explores the intrinsic mechanisms of the MPC protective layer in terms of the resistance of concrete to sulfate. The results showed that the erosion resistance of the concrete to sulfate can be dramatically improved by the MPC protective layer. The structure and composition of the MPC protective layer are different in the sulfate erosion environment compared with those exposed to other environments: the protective layer is more closely bonded to the concrete and has a more compact structure. Therefore, the MPC protective layer is verified to have a significant protective effect on concrete against sulfate corrosion.
      Citation: Coatings
      PubDate: 2018-04-14
      DOI: 10.3390/coatings8040140
      Issue No: Vol. 8, No. 4 (2018)
       
  • Coatings, Vol. 8, Pages 141: Self-Assembled Composite Langmuir Films via
           Fluorine-Containing Bola-Type Derivative with Metal Ions

    • Authors: Nianrui Qu, Shuxin Sun, Qianran Zhao, Tifeng Jiao, Jingxin Zhou, Ruirui Xing, Faming Gao, Lexin Zhang, Qiuming Peng
      First page: 141
      Abstract: The design and preparation of functional bolaamphiphile-based composite films are of key importance for application in a wide variety of fields. This study demonstrates a new approach to constructing composite films by the Langmuir-Blodgett (LB) method using a fluorine-containing bola-type diacid derivative with different metal ions. The bola-type molecule we used could be spread on water surfaces and metal ion subphases to fabricate various nanostructured ultrathin films. The obtained data demonstrated that the employed metal ions, including Ag(I), Cu(II), and Eu(III) ions in subphase solutions, can regulate the organized molecular stacking and form interfacial nanostructures deposited in LB films. It was found that the interfacial coordinating interactions can easily occur between carboxyl groups in a molecular skeleton with metal ions in the formed composite films. The formation of composite films was confirmed by changes in the surface pressure-area isotherms, morphologies, and spectra of the transferred LB films. While various research works have achieved the regulation of functions and nanostructures of sophisticated bola-type compounds, we here demonstrate a simple routine to modulate the nanostructures and organized packing of bola-type compounds composite films by changing the metal ions in subphase solutions.
      Citation: Coatings
      PubDate: 2018-04-14
      DOI: 10.3390/coatings8040141
      Issue No: Vol. 8, No. 4 (2018)
       
  • Coatings, Vol. 8, Pages 142: Efficiently Extracted Cellulose Nanocrystals
           and Starch Nanoparticles and Techno-Functional Properties of Films Made
           Thereof

    • Authors: Christoph Metzger, Solange Sanahuja, Lisa Behrends, Sven Sängerlaub, Martina Lindner, Heiko Briesen
      First page: 142
      Abstract: Cellulose nanocrystals (CNC) and starch nanoparticles (SNP) have remarkable physical and mechanical characteristics. These properties particularly facilitate their application as high-performance components of bio-based packaging films as alternatives to fossil-based counterparts. This study demonstrates a time-efficient and resource-saving extraction process of CNC and SNP by sulfuric acid hydrolysis and neutralization. The yields of the hydrolyzed products were 41.4% (CNC) and 32.2% (SNP) after hydrolysis times of 3 h and 120 h, respectively. The nanoparticle dispersions were wet-coated onto poly(lactic acid) (PLA) and paper substrates and were incorporated into starch films. No purification or functionalization of the nanoparticles was performed prior to their application. Techno-functional properties such as the permeability of oxygen and water vapor were determined. The oxygen permeability of 5–9 cm3 (STP) 100 µm m−2 d−1 bar−1 at 50% relative humidity and 23 °C on PLA makes the coatings suitable as oxygen barriers. The method used for the extraction of CNC and SNP contributes to the economic production of these nanomaterials. Further improvements, e.g., lower ion concentration and narrower particle size distribution, to achieve reproducible techno-functional properties are tangible.
      Citation: Coatings
      PubDate: 2018-04-14
      DOI: 10.3390/coatings8040142
      Issue No: Vol. 8, No. 4 (2018)
       
  • Coatings, Vol. 8, Pages 143: Evaluation of Thermal Degradation of DLC Film
           Using a Novel Raman Spectroscopy Technique

    • Authors: Muyang He, Changdong Yeo
      First page: 143
      Abstract: Diamond-like carbon (DLC) films are extensively used in various industries due to their superior protective and lubrication properties. However, DLC films including sp2 and sp3 carbon bonding are metastable materials, which can be thermally degraded (or graphitized) at elevated temperature. In this study, a novel Raman spectroscopy technique was developed to evaluate the in-situ thermal stability of DLC films. When a laser beam is applied onto a DLC film, the surface temperature can increase depending on the laser power, laser duration time, and surface reflectivity. Based on this laser heating concept, the Raman spectrum data of DLC films (i.e., G peak position and width) were obtained at the controlled Raman laser power, which enabled to determine the critical temperature to initiate the thermal degradation of DLC films. Two different designs of DLC film (i.e., types A and B with different initial sp2-to-sp3 ratio) were prepared and their thermal stability was evaluated using the proposed Raman spectroscopy technique. From the systematic data analysis and comparison, it could be observed that the type-A DLC film showed the significant change of Raman parameters (i.e., G peak position and width) at lower laser power value (=lower temperature) than the type-B DLC film, which indicated that the type-B DLC film had better thermal stability.
      Citation: Coatings
      PubDate: 2018-04-16
      DOI: 10.3390/coatings8040143
      Issue No: Vol. 8, No. 4 (2018)
       
  • Coatings, Vol. 8, Pages 144: Fabrication of Self-healing Superhydrophobic
           Surfaces from Water-Soluble Polymer Suspensions Free of Inorganic
           Particles through Polymer Thermal Reconstruction

    • Authors: Yalun Shen, Yitian Wu, Zhehong Shen, Hao Chen
      First page: 144
      Abstract: Self-healing superhydrophobic surfaces have been fabricated by casting and drying water-soluble amphiphilic polymer suspensions at room temperature through thermal reconstruction. When compared with previous methods, this approach exploits modified natural hierarchical microstructures from wood instead of artificially constructing them for superhydrophobic morphology, which involves neither organic solvent nor inorganic particles nor complex procedures. The obtained superhydrophobic surface has acceptable resistance to abrasion. The surface can recover superhydrophobicity spontaneously at room temperature upon damage, which can be accelerated at a higher temperature. After depleting healing agents, the polymer suspension can be sprayed or cast onto wood surfaces to replenish healing agents and to restore self-healing ability. The superhydrophobic surface greatly increases the mold inhibition and water resistance of wood, which would prolong the service life of wood based materials.
      Citation: Coatings
      PubDate: 2018-04-16
      DOI: 10.3390/coatings8040144
      Issue No: Vol. 8, No. 4 (2018)
       
  • Coatings, Vol. 8, Pages 145: Effects of Laser Microtexturing on the
           Wetting Behavior of Ti6Al4V Alloy

    • Authors: Juan Vazquez-Martinez, Jorge Salguero Gomez, Pedro Mayuet Ares, Severo Fernandez-Vidal, Moises Batista Ponce
      First page: 145
      Abstract: Surface modification procedures by laser techniques allow the generation of specific topographies and microstructures that enable the adaptation of the external layers of materials for specific applications. In laser texturing processes, it is possible to maintain control over the microgeometry and dimensions of the surface pattern through varying the processing parameters. One of the main areas of interest in the field of surface modification treatments is the ability to generate topographies that are associated with specific surface finishes, in terms of roughness, that can improve the manufactured part’s functional capabilities. In this aspect, several types of phenomena have been detected, such as the friction and sliding wear behavior or wetting capacity, which maintain a high dependence on surface roughness. In this research, surface texturing treatments have been developed by laser techniques through using the scanning speed of the beam (Vs) as a control parameter in order to generate samples that have topographies with different natures. Through assessments of surface finish using specialized techniques, the dimensional and geometrical features of the texturized tracks have been characterized, analyzing their influence on the wetting behavior of the irradiated layer. In this way, more defined texturing grooves has been developed by increasing the Vs, which also improves the hydrophobic characteristics of the treated surface. However, due to the lack of uniformity in the solidification process of the irradiated area, some deviations from the expected trends and singular points can be observed. Using the contact angle method to evaluate the wetting behavior of the applied treatments found increases in the contact angle values for high texturing speeds, finding a maximum value of 65.59° for Vs = 200 mm/s.
      Citation: Coatings
      PubDate: 2018-04-17
      DOI: 10.3390/coatings8040145
      Issue No: Vol. 8, No. 4 (2018)
       
  • Coatings, Vol. 8, Pages 146: Target Voltage Hysteresis Behavior and
           Control Point in the Preparation of Aluminum Oxide Thin Films by Medium
           Frequency Reactive Magnetron Sputtering

    • Authors: Qingfu Wang, Liping Fang, Qinghe Liu, Lin Chen, Qinguo Wang, Xiandong Meng, Hong Xiao
      First page: 146
      Abstract: Aluminum oxide thin films were prepared by medium frequency reactive magnetron sputtering. The target voltage hysteresis behavior under different argon partial pressure and target power conditions were studied. The results indicate that the target voltage hysteresis loop of aluminum oxide thin film preparation has typical behavior of that for reactive sputtering deposition of compound films. The target voltage feedback control approach was applied to circumvent the hysteresis problem. The microstructure and chemical composition of the aluminum oxide thin films prepared at different target voltage control points were investigated by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and Auger electron spectroscopy. The results indicated that the prepared aluminum oxide thin films, which are compact and mostly amorphous, can be obtained with target voltage control point in the range of 25~35%.
      Citation: Coatings
      PubDate: 2018-04-18
      DOI: 10.3390/coatings8040146
      Issue No: Vol. 8, No. 4 (2018)
       
  • Coatings, Vol. 8, Pages 147: Hydrocolloid-Based Coatings are Effective at
           Reducing Acrylamide and Oil Content of French Fries

    • Authors: Asmaa Al-Asmar, Daniele Naviglio, Concetta Valeria L. Giosafatto, Loredana Mariniello
      First page: 147
      Abstract: French fries are popular products worldwide. However, this product is a sufferable source of high acrylamide due to high temperature and low moisture. The main objective of this study was to evaluate the effect of grass pea flour (GPF), transglutaminase (TGase)-treated (GPF + TGase), chitosan (CH), and pectin (PEC) hydrocolloid coating solutions on the formation of acrylamide, water retention as well as on oil content. In addition, the Daily Intake (DI) and Margin of Exposure (MOE) were calculated to estimate variations in risk assessment by applying coating solutions before frying. Our results showed that the highest acrylamide content was detected in the control sample, reaching a value of 2089 µg kg−1. Hydrocolloid coating solutions were demonstrated to be an effective way to reduce acrylamide formation, with the percentage of acrylamide reduction equal to 48% for PEC, >38% for CH, ≥37% for GPF + TGase, and >31% for GPF, respectively. We hypothesized that the coatings were able to increase the water retention and, thus reduce the Maillard reaction, which is responsible for acrylamide formation. In fact, the MOE value for coated French fries was increase, resulting in being closer to the safety level to avoid carcinogenic risk. Moreover, our coatings were effective in reducing oil uptake.
      Citation: Coatings
      PubDate: 2018-04-18
      DOI: 10.3390/coatings8040147
      Issue No: Vol. 8, No. 4 (2018)
       
  • Coatings, Vol. 8, Pages 148: One-Step Fabrication and Localized
           Electrochemical Characterization of Continuous Al-Alloyed Intermetallic
           Surface Layer on Magnesium Alloy

    • Authors: Zhenxuan Fu, Xu Chen, Bin Liu, Jie Liu, Xiaopeng Han, Yida Deng, Wenbin Hu, Cheng Zhong
      First page: 148
      Abstract: A continuous intermetallic compound coating was fabricated on AZ91D magnesium alloy via heat treatment at 400 °C in AlCl3-NaCl molten salts for 10 h. The microstructure and composition of the coating were characterized by scanning electron microscope and energy dispersive X-ray spectrometry. The results showed that the coating has a two-layer structure (the outer Mg2Al3 phase layer and the inner Mg17Al12 phase layer) up to 37 μm thick with compact and planar interfaces between the layers and the substrate. The corrosion property of the coating was investigated using electrochemical impedance spectroscopy (EIS) and two localized electrochemical techniques, i.e., localized electrochemical impedance spectroscopy (LEIS) and scanning vibrating electrode technique (SVET). The charge transfer resistance (Rct) of the Al-alloyed coating was 2119 Ω cm2. The localized impedance and current density maps obtained through LEIS and SVET indicate not only significantly improved corrosion resistance (the impedance modulus increased by one order of magnitude and the current density decreased to approximately 3.8%, compared with the substrate) but also defect-free surface condition.
      Citation: Coatings
      PubDate: 2018-04-18
      DOI: 10.3390/coatings8040148
      Issue No: Vol. 8, No. 4 (2018)
       
  • Coatings, Vol. 8, Pages 149: Effects of Graphene-Oxide-Modified Coating on
           the Properties of Carbon-Fiber-Reinforced Polypropylene Composites

    • Authors: Sean Bowman, Xiaoyu Hu, Qiuran Jiang, Yiping Qiu, Wanshuang Liu, Yi Wei
      First page: 149
      Abstract: Graphene oxide (GO) modified with ferrites (GO@Fe3O4) were studied to determine their effect on the interfacial properties of continuous carbon-fiber-reinforced thermoplastic composites. The GO@Fe3O4 were introduced by mixing them directly in an acrylic-styrene (AS) sizing emulsion suitable for the making of continuous carbon-fiber-reinforced thermoplastics and towpregs. A magnetic field was then generated during the online sizing using coils in order to change the morphology of the coating on the fiber. The effect on the obtained sizing quality and final properties of continuous carbon-fiber-reinforced thermoplastic composites was then studied. The results showed that the topography of the sized fibers was modified, showing a kind of “drag” effect and more than a 32% increase was obtained for interlaminar shear strength.
      Citation: Coatings
      PubDate: 2018-04-19
      DOI: 10.3390/coatings8040149
      Issue No: Vol. 8, No. 4 (2018)
       
  • Coatings, Vol. 8, Pages 150: Effects of Annealing on Residual Stress in
           Ta2O5 Films Deposited by Dual Ion Beam Sputtering

    • Authors: Qipeng Lv, Mingliang Huang, Shaoqian Zhang, Songwen Deng, Faquan Gong, Feng Wang, Yanwei Pan, Gang Li, Yuqi Jin
      First page: 150
      Abstract: Optical coatings deposited by the dual ion beam sputtering (DIBS) method usually show high compressive stress, which results in severe wavefront deformation of optical elements. Annealing post-treatment has been widely used to control the residual stress of optical coatings. However, the effect of annealing on the stress of Ta2O5 films deposited by the IBS method has not been reported in detail. In this study, different thicknesses of Ta2O5 films were deposited by IBS and annealed at different temperatures from 473 to 973 K in air, and the effect of annealing on the stress of Ta2O5 films was investigated. The as-deposited Ta2O5 films deposited by IBS show high compressive stress, which are about 160 MPa. The compressive stress decreases linearly with the increasing temperature, and the wavefront deformation of Ta2O5 films increases linearly with film thickness (within 20 μm) at the same annealing temperature. When the temperature rises to 591 K, Ta2O5 films with zero-stress can be obtained. Ta2O5 films show tensile stress instead of compressive stress with further increasing annealing temperature, and the tensile stress increases with increasing temperature. Meanwhile, with the increasing annealing temperature, the refractive index of Ta2O5 film decreases, indicating the decreasing packing density. The atomic force microscope (AFM) test results show that surface roughness of Ta2O5 films slowly increases with the increasing of annealing temperature. Moreover, X-ray photoelectron spectroscopy (XPS) analysis shows that the Ta in Ta2O5 films can be further oxidized with increasing annealing temperature, namely, the absorption of Ta2O5 film can be reduced. X-ray diffraction (XRD) analysis shows that the annealing temperature should be below 923 K to maintain the amorphous structure of the Ta2O5 film.
      Citation: Coatings
      PubDate: 2018-04-20
      DOI: 10.3390/coatings8040150
      Issue No: Vol. 8, No. 4 (2018)
       
  • Coatings, Vol. 8, Pages 151: Anti-Icing Performance of Hydrophobic
           Silicone–Acrylate Resin Coatings on Wind Blades

    • Authors: Ke Xu, Jianlin Hu, Xingliang Jiang, Wei Meng, Binhuan Lan, Lichun Shu
      First page: 151
      Abstract: The icing of wind blades poses a serious threat to the operation of wind turbines. The application of superhydrophobic coatings on wind blades can serve as a potential anti-icing method. This study presents the findings of simulations of the icing environment of wind blades coated with hydrophobic silicone–acrylate resin in an artificial climate chamber. Artificial icing tests were performed on NACA7715 wind blades with four different silicone–acrylate resin coatings and on uncoated wind blades, with test performed at five different wind speeds and three different angles of attack. Results show that wind blade surfaces with higher hydrophobicity yield better anti-icing performance, and that the ice mass of the wind blades decreases with increasing wind speeds and angles of attack. In addition, variations in ice mass, shape, and distribution on different wind blades indicate that increased hydrophobicity can help limit the areas that are subject to freezing. Hydrophobicity can affect the air cavities of the ice deposited on the wind blades, and surfaces with increased hydrophobicity can lead to lower ice mass and less ice adhesion. In brief, surfaces with higher hydrophobicity demonstrate better anti-icing performance and benefit from active de-icing.
      Citation: Coatings
      PubDate: 2018-04-23
      DOI: 10.3390/coatings8040151
      Issue No: Vol. 8, No. 4 (2018)
       
 
 
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