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  Subjects -> ENGINEERING (Total: 2282 journals)
    - CHEMICAL ENGINEERING (192 journals)
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    - ELECTRICAL ENGINEERING (102 journals)
    - ENGINEERING (1204 journals)
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ENGINEERING (1204 journals)                  1 2 3 4 5 6 7 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 7)
3D Research     Hybrid Journal   (Followers: 19)
AAPG Bulletin     Hybrid Journal   (Followers: 6)
AASRI Procedia     Open Access   (Followers: 15)
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: 233)
Acta Geotechnica     Hybrid Journal   (Followers: 7)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 2)
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: 6)
Advanced Science     Open Access   (Followers: 5)
Advanced Science Focus     Free   (Followers: 3)
Advanced Science Letters     Full-text available via subscription   (Followers: 7)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 7)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17)
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: 25)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 15)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 10)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 21)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 28)
Advances in Operations Research     Open Access   (Followers: 11)
Advances in OptoElectronics     Open Access   (Followers: 5)
Advances in Physics Theories and Applications     Open Access   (Followers: 12)
Advances in Polymer Science     Hybrid Journal   (Followers: 41)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Remote Sensing     Open Access   (Followers: 37)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aerobiologia     Hybrid Journal   (Followers: 1)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 4)
AIChE Journal     Hybrid Journal   (Followers: 30)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access  
Alexandria Engineering Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 28)
American Journal of Engineering and Applied Sciences     Open Access   (Followers: 11)
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: 23)
Analele Universitatii Ovidius Constanta - Seria Chimie     Open Access  
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
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)
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: 15)
Applied Clay Science     Hybrid Journal   (Followers: 5)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 4)
Applied Nanoscience     Open Access   (Followers: 8)
Applied Network Science     Open Access  
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Physics Research     Open Access   (Followers: 3)
Applied Sciences     Open Access   (Followers: 2)
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: 4)
Archives of Foundry Engineering     Open Access  
Archives of Thermodynamics     Open Access   (Followers: 7)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ASEE Prism     Full-text available via subscription   (Followers: 3)
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: 8)
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: 4)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 23)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 4)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Motor Trade Survey     Full-text available via subscription   (Followers: 1)
BER : Retail Sector Survey     Full-text available via subscription   (Followers: 2)
BER : Retail Survey : Full Survey     Full-text available via subscription   (Followers: 2)
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)
Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Biofuels Engineering     Open Access  
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 10)
Biomedical Engineering     Hybrid Journal   (Followers: 16)
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: 17)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 31)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 9)
Biomedical Science and Engineering     Open Access   (Followers: 4)
Biomedizinische Technik - Biomedical Engineering     Hybrid Journal  
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 2)
Biotechnology Progress     Hybrid Journal   (Followers: 39)
Boletin Cientifico Tecnico INIMET     Open Access  
Botswana Journal of Technology     Full-text available via subscription  
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access   (Followers: 2)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 10)
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 14)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 3)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 14)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 41)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 8)
Case Studies in Thermal Engineering     Open Access   (Followers: 3)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 6)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 8)
CEAS Space Journal     Hybrid Journal  
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 3)
Central European Journal of Engineering     Hybrid Journal   (Followers: 1)
CFD Letters     Open Access   (Followers: 6)
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: 1)
CienciaUAT     Open Access  
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: 14)
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: 2)
Coal Science and Technology     Full-text available via subscription   (Followers: 3)
Coastal Engineering     Hybrid Journal   (Followers: 11)
Coastal Engineering Journal     Hybrid Journal   (Followers: 5)
Coatings     Open Access   (Followers: 3)
Cogent Engineering     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Color Research & Application     Hybrid Journal   (Followers: 1)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 13)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 13)
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: 26)
Composite Interfaces     Hybrid Journal   (Followers: 6)
Composite Structures     Hybrid Journal   (Followers: 258)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 181)
Composites Part B : Engineering     Hybrid Journal   (Followers: 237)
Composites Science and Technology     Hybrid Journal   (Followers: 216)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (Followers: 14)
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: 6)
Computer Science and Engineering     Open Access   (Followers: 17)
Computers & Geosciences     Hybrid Journal   (Followers: 28)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 5)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 4)
Computers and Geotechnics     Hybrid Journal   (Followers: 10)
Computing and Visualization in Science     Hybrid Journal   (Followers: 5)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 30)
Conciencia Tecnologica     Open Access  
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 6)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 9)
Control Engineering Practice     Hybrid Journal   (Followers: 42)
Control Theory and Informatics     Open Access   (Followers: 8)
Corrosion Science     Hybrid Journal   (Followers: 25)
CT&F Ciencia, Tecnologia y Futuro     Open Access  
CTheory     Open Access  
Current Applied Physics     Full-text available via subscription   (Followers: 4)
Current Science     Open Access   (Followers: 58)

        1 2 3 4 5 6 7 | Last

Journal Cover Coatings
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  This is an Open Access Journal Open Access journal
   ISSN (Online) 2079-6412
   Published by MDPI Homepage  [156 journals]
  • Coatings, Vol. 7, Pages 133: Recent Development in Phosphonic Acid-Based
           Organic Coatings on Aluminum

    • Authors: Ruohan Zhao, Patrick Rupper, Sabyasachi Gaan
      First page: 133
      Abstract: Research on corrosion protection of aluminum has intensified over the past decades due to environmental concerns regarding chromate-based conversion coatings and also the higher material performance requirements in automotive and aviation industries. Phosphonic acid-based organic and organic-inorganic coatings are increasingly investigated as potential replacements of toxic and inefficient surface treatments for aluminum. In this review, we have briefly summarized recent work (since 2000) on pretreatments or coatings based on various phosphonic acids for aluminum and its alloys. Surface characterization methods, the mechanism of bonding of phosphonic acids to aluminum surface, methods for accessing the corrosion behavior of the treated aluminum, and applications have been discussed. There is a clear trend to develop multifunctional phosphonic acids and to produce hybrid organic-inorganic coatings. In most cases, the phosphonic acids are either assembled as a monolayer on the aluminum or incorporated in a coating matrix on top of aluminum, which is either organic or organic-inorganic in nature. Increased corrosion protection has often been observed. However, much work is still needed in terms of their ecological impact and adaptation to the industrially-feasible process for possible commercial exploitation.
      Citation: Coatings
      PubDate: 2017-08-23
      DOI: 10.3390/coatings7090133
      Issue No: Vol. 7, No. 9 (2017)
       
  • Coatings, Vol. 7, Pages 134: Design of Nano-Porous Multilayer
           Antireflective Coatings

    • Authors: Joel Loh, Nazir Kherani
      First page: 134
      Abstract: We present an overview of the design potential of nano-porous anti-reflection coatings (ARCs) and the associated challenges in its fabrication. Genetic algorithm optimization for the most effective ARCs on glass for normal and all incident angles is carried out and an admittance loci-based pictorial is used to visualize their performance. We then describe the advantages of using nano-porous multi-layers vis-à-vis other types of moth-eye type nano-grating films: Principally trading high performance and high cost of fabrication for good performance and lower cost facile synthesis. We describe some of the issues involved in the fabrication of such multi-layer stacks on glass and polymeric substrates and provide suggestions for overcoming these limitations.
      Citation: Coatings
      PubDate: 2017-08-26
      DOI: 10.3390/coatings7090134
      Issue No: Vol. 7, No. 9 (2017)
       
  • Coatings, Vol. 7, Pages 135: Microstructure and Mechanism of Grain Raising
           in Wood

    • Authors: Philip Evans, Ian Cullis, Joseph Kim, Lukie Leung, Siti Hazneza, Roger Heady
      First page: 135
      Abstract: Grain raising, the lifting of fibres when water is applied to wood surfaces, is a reason why some companies are reluctant to finish wood products with water-borne coatings. However, the elements that lift-up and cause grain raising have not been identified, and the relationship between wood density and grain raising has not been clarified. Our work sought answers to both questions. We planed or sanded different woods using aluminum oxide abrasive paper, and characterized surfaces using profilometry and SEM. Surfaces were re-characterized after wetting and drying. Grain raising is inversely related to wood density. In particular, very low-density woods are highly susceptible to grain raising, whereas grain raising does not occur in high-density woods or planed woods. In low-density woods, sanding tears cell walls creating loosely-bonded slivers of wood that project from surfaces, particularly after wetting and drying. This mechanism for grain raising was confirmed by modelling the action of abrasives on wood cell walls using an array of hollow tubes and a serrated tool. Less commonly, fibres and fibre-bundles project from surfaces. We observed that grain raising was correlated with the coarseness of the abrasive and conclude that it can be reduced in severity by tailoring sanding to account for the density and surface microstructure of wood.
      Citation: Coatings
      PubDate: 2017-08-29
      DOI: 10.3390/coatings7090135
      Issue No: Vol. 7, No. 9 (2017)
       
  • Coatings, Vol. 7, Pages 136: Epitaxial Growth of AlN on (0001) Sapphire:
           Assessment of HVPE Process by a Design of Experiments Approach

    • Authors: Raphaël Boichot, Danying Chen, Frédéric Mercier, Francis Baillet, Gaël Giusti, Thomas Coughlan, Mikhail Chubarov, Michel Pons
      First page: 136
      Abstract: This study aims to present the interest of using a design of experiments (DOE) approach for assessing, understanding and improving the hydride vapor phase epitaxy (HVPE) process, a particular class of chemical vapor deposition (CVD) process. The case of the HVPE epitaxial growth of AlN on (0001) sapphire will illustrate this approach. The study proposes the assessment of the influence of 15 process parameters on the quality or desired properties of the grown layers measured by 9 responses. The general method used is a screening design with the Hadamard matrix of order 16. For the first time in the growth of AlN by CVD, a reliable estimation of errors is proposed on the measured responses. This study demonstrates that uncontrolled release of condensed species from the cold wall is the main drawback of this process, explaining many properties of the grown layers that could be mistakenly attributed to other phenomena without the use of a DOE. It appears also that the size of nucleation islands, and its corollary, the stress state of the layer at room temperature, are key points. They are strongly correlated to the crystal quality. Due to the intrinsic limitations of the screening design, the complete optimization of responses cannot be proposed but general guidelines for hydride (or halogen) vapor phase epitaxy (HVPE) experimentations, in particular with cold wall apparatus, are given.
      Citation: Coatings
      PubDate: 2017-09-01
      DOI: 10.3390/coatings7090136
      Issue No: Vol. 7, No. 9 (2017)
       
  • Coatings, Vol. 7, Pages 137: Research on Microstructure, Mechanical and
           Tribological Properties of Cr-Ti-B-N Films

    • Authors: Lihua Yu, Huang Luo, Jianguo Bian, Hongbo Ju, Junhua Xu
      First page: 137
      Abstract: In this study, the Cr-Ti-B-N composite thin films with different Ti and B contents in the films were fabricated by a reactive magnetron sputtering system using chromium (Cr) and TiB2 targets. The microstructure, mechanical properties, and friction properties over broad ranges of temperature were detected by XRD, SEM, TEM, nano-indentation, 3D profilometer, and tribometer. It was found that the Cr-Ti-B-N films exhibited a double face-centered cubic (fcc)-CrN and amorphous-BN structure. As the Ti and B elements were introduced, the hardness and elastic modulus of Cr-Ti-B-N films increased from 21 and 246.5 GPa to a maximum value of approximately 28 and 283.6 GPa for Cr38.7Ti3.7B6.4N51.2 film, and then decreased slightly with a further increase of Ti and B contents. The hardness enhancement was attributed to the residual compressive stress. The friction and wear resistance of the film was improved obviously by the addition of Cr and B, as compared with the CrN film under 200 °C.
      Citation: Coatings
      PubDate: 2017-09-03
      DOI: 10.3390/coatings7090137
      Issue No: Vol. 7, No. 9 (2017)
       
  • Coatings, Vol. 7, Pages 138: Thermal Transport on Graphene-Based Thin
           Films Prepared by Chemical Exfoliations from Carbon Nanotubes and Graphite
           Powders

    • Authors: Jian-De Xie, Si-Yong Gu, Houan Zhang
      First page: 138
      Abstract: Thermal conductivities (k) of different graphene nanosheet (GN)-based heat sinks are investigated within the temperature range of 323–423 K. One- and two-step modified Hummers’ methods are adopted to chemically exfoliate GNs from two kinds of carbon precursors: carbon nanotubes (CNTs) and graphite powders. The two-step method offers an improved exfoliation level of GN products, especially for the CNT precursor. Experimental results show that the GN-based heat sink—exfoliated from graphite powders after the two-step approach—delivers an enhanced k value to 2507 W/m K at 323 K, as compared to the others. The k value is found to be a decreasing function of the porosity of the heat sink, revealing the importance of solid/void fraction (i.e., volumetric heat capacity). The improved thermal efficiency mainly originates from the long phonon mean free path and the low void fraction of GN-based heat sinks, thus inducing highly efficient thermal transport in the GN framework.
      Citation: Coatings
      PubDate: 2017-09-03
      DOI: 10.3390/coatings7090138
      Issue No: Vol. 7, No. 9 (2017)
       
  • Coatings, Vol. 7, Pages 139: Texture Analysis of Hydrophobic Polycarbonate
           and Polydimethylsiloxane Surfaces via Persistent Homology

    • Authors: Ali Duman, Bekir Yilbas, Harun Pirim, Haider Ali
      First page: 139
      Abstract: Due to recent climate change-triggered, regular dust storms in the Middle East, dust mitigation has become the critical issue for solar energy harvesting devices. One of the methods to minimize and prevent dust adhesion and create self-cleaning abilities is to generate hydrophobic characteristics on surfaces. The purpose of this study is to explore the topological features of hydrophobic surfaces. We use non-standard techniques from topological data analysis to extract morphological features from the AFM images. Our method recovers most of the previous qualitative observations in a robust and quantitative way. Persistence diagrams, which is a summary of topological structures, witness quantitatively that the crystallized polycarbonate (PC) surface possesses spherulites, voids, and fibrils, and the texture height and spherulite concentration increases with the increased immersion period. The approach also shows that the polydimethylsiloxane (PDMS) exactly copied the structures at the PC surface but 80 to 90 percent of the nanofibrils were not copied at PDMS surface. We next extract a feature vector from each persistence diagram to show which experiments hold features with similar variance using principal component analysis (PCA). The K-means clustering algorithm is applied to the matrix of feature vectors to support the PCA result, grouping experiments with similar features.
      Citation: Coatings
      PubDate: 2017-09-03
      DOI: 10.3390/coatings7090139
      Issue No: Vol. 7, No. 9 (2017)
       
  • Coatings, Vol. 7, Pages 140: The Effect of Glancing Angle Deposition
           Conditions on the Morphology of a Silver Nanohelix Array

    • Authors: Yi-Jun Jen, Yueh Weng Lin, Yu-Jie Huang, Teh-Li Chan
      First page: 140
      Abstract: Silver nanohelices were grown on smooth substrates using glancing angle deposition and substrate cooling. Various nanohelix arrays were deposited under different deposition conditions—different deposition rates, substrate spin rates, deposition angles, and substrate temperatures. The effect of deposition conditions on the morphology of each nanohelix array in terms of pitch angle, pitch length, wire diameter, and radius of curvature was investigated. The dependence of circular dichroism on the size of the nanohelix arrays was also measured and demonstrated.
      Citation: Coatings
      PubDate: 2017-09-04
      DOI: 10.3390/coatings7090140
      Issue No: Vol. 7, No. 9 (2017)
       
  • Coatings, Vol. 7, Pages 141: Interlayers Applied to CVD Diamond Deposition
           on Steel Substrate: A Review

    • Authors: Djoille Damm, André Contin, Fernando Barbieri, Vladimir Trava-Airoldi, Danilo Barquete, Evaldo Corat
      First page: 141
      Abstract: Academics and industry have sought after combining the exceptional properties of diamonds with the toughness of steel. Since the early 1990s several partial solutions have been found but chemical vapor deposition (CVD) diamond deposition on steel substrate continues to be a persistent problem. The main drawbacks are the high carbon diffusion from gas phase into substrate, the transition metals on the material surface that catalyze sp2 bond formation, instead of sp3 bonds, and the high thermal expansion coefficient (TEC) mismatch between diamond and steels. An intermediate layer has been found necessary to increase diamond adhesion. Literature has proposed many efficient intermediate layers as a diffusion barrier for both, carbon and iron, but most intermediate layers shown have not solved TEC mismatch. In this review, we briefly discuss the solutions that exclusively work as diffusion barrier and discuss in a broader way the ones that also solve, or may potentially solve, the TEC mismatch problem. We examine some multilayers, the iron borides, the chromium carbides, and vanadium carbides. We go through the most relevant results of the last two and a half decades, including recent advances in our group. Vanadium carbide looks promising since it has shown excellent diffusion barrier properties, its TEC is intermediary between diamond and steel and, it has been thickened to manage thermal stress relief. We also review a new deposition technique to set up intermediate layers: laser cladding. It is promising because of its versatility in mixing different materials and fusing and/or sintering them on a steel surface. We conclude by remarking on new perspectives.
      Citation: Coatings
      PubDate: 2017-09-08
      DOI: 10.3390/coatings7090141
      Issue No: Vol. 7, No. 9 (2017)
       
  • Coatings, Vol. 7, Pages 142: Zircon-Based Ceramic Coatings Formed by a New
           Multi-Chamber Gas-Dynamic Accelerator

    • Authors: Marina Kovaleva, Mayya Prozorova, Maria Arseenko, Yuri Tyurin, Oleg Kolisnichenko, Maxim Yapryntsev, Vseslav Novikov, Olga Vagina, Viacheslav Sirota
      First page: 142
      Abstract: In this work, dense zircon-based ceramic coatings were obtained from inexpensive zircon powder on a steel substrate by using a new multi-chamber gas-dynamic accelerator. The microstructure and phase composition of the coating were characterized by scanning electron microscopy, optical microscopy, and X-ray diffraction. The mechanical properties of the coatings were evaluated using microindentation, wear tests and bonding strength tests. The results showed that the obtained zircon-based ceramic coatings were continuous without cracks and bonded well with substrate without a sublayer. The zircon-based ceramic coatings consisted of c-ZrO2 (major phase), m-ZrO2 and SiO2. The zircon-based ceramic coatings had a porosity of 0.1%, hardness of 526 ± 65 HV0.2, and a fracture toughness of 2.5 ± 0.6 (МPа∙m1/2). The coatings showed the low specific wear rate and average erosion rate. The failure mode occurring in the tested coatings was cohesive.
      Citation: Coatings
      PubDate: 2017-09-08
      DOI: 10.3390/coatings7090142
      Issue No: Vol. 7, No. 9 (2017)
       
  • Coatings, Vol. 7, Pages 143: A Comparative Study on the Elastic
           Characteristics of an Aluminum Thin-Film Using Laser Optical Measurement
           Techniques

    • Authors: Seonwook Lee, Yun Kim, Younho Cho
      First page: 143
      Abstract: The increase of a surface area-to-volume ratio with the reduction of material dimensions significantly alters the characteristics of materials from their macroscopic status. Therefore, efforts have been made to establish evaluation techniques for nanoscale films. While contact mechanics-based techniques are conventionally available, non-contact and nondestructive methods would be preferable in case damages left on a sample after testing are not desirable, or an in situ assessment is required. In the present study, the Young’s modulus of an aluminum thin-film was evaluated using two different laser optical measurement techniques. First, microscale beam testing has been performed so that the resonant frequency change of a microfabricated cantilever beam induced by coating of a 153 nm thick aluminum layer on its top surface can be detected using a laser interferometer in order to evaluate the mechanical property through modal analysis using the finite element method. Second, picosecond ultrasonics were employed for cross-verification so that the mechanical characteristics can be evaluated through the investigation of the longitudinal bulk wave propagation behavior. Results show that the Young’s moduli from both measurements agree well with each other within 3.3% error, proving that the proposed techniques are highly effective for the study of nanoscale films.
      Citation: Coatings
      PubDate: 2017-09-10
      DOI: 10.3390/coatings7090143
      Issue No: Vol. 7, No. 9 (2017)
       
  • Coatings, Vol. 7, Pages 144: Microstructure and Wear Resistance of
           AlCoCrFeNiTi High-Entropy Alloy Coatings Produced by HVOF

    • Authors: Martin Löbel, Thomas Lindner, Thomas Mehner, Thomas Lampke
      First page: 144
      Abstract: The investigation of high-entropy alloys (HEAs) has revealed many promising properties. HEAs with a high share of Al and Ti are suitable for the formation of lightweight materials. Investigations of the alloy system AlCoCrFeNiTi showed high strength, hardness, ductility, and wear resistance, which makes this special alloy interesting for surface engineering and particularly for thermal spray technology. In this study, the suitability of inert gas-atomised HEA powder for high-velocity-oxygen-fuel (HVOF) thermal spray is investigated. This process allows for high particle velocities and comparatively low process temperatures, resulting in dense coatings with a low oxidation. The microstructure and phase composition of the atomised powder and the HVOF coating were investigated, as well as the wear behaviour under various conditions. A multiphase microstructure was revealed for the powder and coating, whereas a chemically ordered bcc phase occurred as the main phase. The thermal spray process resulted in a slightly changed lattice parameter of the main phase and an additional phase. In comparison with a hard chrome-plated sample, an increase in wear resistance was achieved. Furthermore, no brittle behaviour occurred under abrasive load in the scratch test. The investigation of wear tracks showed only minor cracking and spallation under maximum load.
      Citation: Coatings
      PubDate: 2017-09-12
      DOI: 10.3390/coatings7090144
      Issue No: Vol. 7, No. 9 (2017)
       
  • Coatings, Vol. 7, Pages 145: In Vitro Assessment of Sericin-Silver
           Functionalized Silk Fabrics for Enhanced UV Protection and Antibacterial
           Properties Using Experimental Design

    • Authors: Pisutsaran Chitichotpanya, Chayanisa Chitichotpanya
      First page: 145
      Abstract: Silk sericin (SS) was used as both a 3-dimensional matrix and reductant for the in situ synthesis of silver nanoparticles (AgNPs) finished on silk fabrics. We demonstrated enhanced UV protection and antibacterial properties using this synthesis which was an environmental friendly approach. Development and optimization was achieved using a central composite design (CCD) in conjunction with the response surface methodology (RSM). The goal was to identify the concentrations of SS and AgNO3 that produced the optimal balance between UV protection and antibacterial activity, when tested against E. coli and S. aureus. The SS-AgNP bio-nanocomposites were characterized using Scanning Electron Microscope (SEM-EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). Statistical analyses indicated an empirical second-order polynomial could accurately model the experimental values. To confirm that the optimal levels from RSM worked in practice, performance evaluations were conducted, including tests of cytotoxicity, of the durability and stability of UV protection, as well as of the antibacterial activity of the functionalized fabrics after repeated standard washing. The results suggest that these bio-nanocomposites have great potential for multi-functionalization on silk fabrics. Our method has been shown to convert the waste material (SS) to a fabric with high added value.
      Citation: Coatings
      PubDate: 2017-09-13
      DOI: 10.3390/coatings7090145
      Issue No: Vol. 7, No. 9 (2017)
       
  • Coatings, Vol. 7, Pages 146: Effect of Waveform and Heat Treatment
           Processes on the Performance of Electrodeposited Co-P Coating

    • Authors: Xiaomei Chen, Jiangang Qian, Xiaotian Hu
      First page: 146
      Abstract: Cobalt-phosphorus (Co-P) alloy is a promising material for the replacement of traditional hard chromium alloy of high hardness. In this paper, the cobalt-phosphorus alloy layer with high phosphorus content was formed by electrodeposition in a cobalt sulfate solution system under direct current (DC), single pulse (SP) current and double pulse (DP) current, separately. Surface morphology, structure and properties of the deposited layer were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), Vickers microhardness and a neutral salt spray test, respectively. The results showed that the dense Co-P coatings could be obtained by DC, SP and DP with P content of 9.6, 8.9 and 9.1 wt %, respectively. After 30 min heat treatment at 400 °C, coatings deposited under DC, SP and DP currents transformed from an amorphous to a nanocrystalline state, while the grain size was 12–13 nm, 10–12 nm and 8–10 nm, respectively. Among all these conditions, the microhardness of coatings deposited under DP current was the highest, which was 1211 HV, while the microhardness of coatings deposited under DC current was the lowest but higher than that of hard chromium. The wear rate of Co-P coatings was 4 × 10−6–5 × 10−6 mm3/N m with Si3N4 ball as bearing material, which was lower than that of hard chromium. In coatings deposited under different currents with a thickness of ca. 40 μm, no visible corrosion area appeared after 1000 h of a neutral salt spray test. Coatings heated at 300 and 400 °C reached the corrosion grade 7 and grade 4–5, respectively after 1000 h of a neutral salt spray test, so the wear resistance of Co-P coatings was better than that of hard chromium.
      Citation: Coatings
      PubDate: 2017-09-15
      DOI: 10.3390/coatings7090146
      Issue No: Vol. 7, No. 9 (2017)
       
  • Coatings, Vol. 7, Pages 147: Particle Velocities near and along the
           Electrode during Electrophoretic Deposition: Influence of Surfactant
           Counter-Ions

    • Authors: Claudine Filiâtre, Céline Pignolet, Cédric Buron
      First page: 147
      Abstract: Research into the micro-nanostructured coatings process has made a variety of new applications available. Electrophoretic deposition (EPD) is an efficient and attractive technique to produce coated materials. Therefore the understanding of the formation and growth mechanism of the coating process continues to be investigated. In this study, a home-made EPD laminar flow cell was used for in-situ investigation of the particle velocity and deposition of micronic particles on a cathode. Monodisperse polystyrene latex particles were functionalized with cationic surfactants: cetyltrimethyl ammonium bromide (CTAB) or cetyltrimethyl ammonium chloride (CTAC). The tangential velocity of the particles when they migrated to the electrode, the approach angle and the tangential velocity along the electrode were measured under a DC electric field. From the values of the velocities, the particle-electrode distance was evaluated in CTAB and CTAC solutions. The electrophoretic velocity was calculated from the electrophoretic mobility of the particles and the electric field applied to the particles. All these parameters depend on the type of surfactant counter-ions and influence the growth of the coating. Dense structures were obtained in CTAB solution while open structures were observed in CTAC solution.
      Citation: Coatings
      PubDate: 2017-09-14
      DOI: 10.3390/coatings7090147
      Issue No: Vol. 7, No. 9 (2017)
       
  • Coatings, Vol. 7, Pages 148: Deposition and Patterning of Polycrystalline
           

    • Authors: Stepan Linnik, Vitalii Okhotnikov, Alexander Gaydaychuk
      First page: 148
      Abstract: Given the exceptional characteristics of diamond films, they have become increasingly popular in the fields of medicine, microelectronics, and detector electronics. However, despite all the advantages, there are many technological problems that complicate their widespread application and impose limitations on diamond use in technological processes. In this study, we proposed a new technique for obtaining a complex topology of polycrystalline diamond coatings by selective seeding of the substrate by nucleation centers and subsequent surface treatment with reactive ion etching to reduce the number of parasitic particles. As a result, diamond films were obtained with a high particle concentration in the film region and high repeatability of the pattern. Moreover, parasitic particles influenced neutralization in areas where film coverage was not needed. The effect of the diamond nanoparticle concentration in a photoresist and the effect of reactive ion etching on the formation of a continuous film and the removal of parasitic nucleation centers were examined. The relative simplicity, low power consumption, and high efficiency of this method make it attractive for both industrial and scientific applications.
      Citation: Coatings
      PubDate: 2017-09-15
      DOI: 10.3390/coatings7090148
      Issue No: Vol. 7, No. 9 (2017)
       
  • Coatings, Vol. 7, Pages 149: Hybrid Ti-MoS2 Coatings for Dry Machining of
           Aluminium Alloys

    • Authors: Tomasz Brzezinka, Jeff Rao, Mohamad Chowdhury, Joern Kohlscheen, German Fox Rabinovich, Stephen Veldhuis, Jose Endrino
      First page: 149
      Abstract: Combinatorial deposition, comprising filtered cathodic vacuum arc (FCVA) and physical vapor deposition (PVD) magnetron sputtering is employed to deposit molybdenum disulphide (MoS2) and titanium (Ti) thin films onto TiB2-coated tool inserts specifically designed for the dry machining of aluminium alloys. Titanium is deposited by FCVA while MoS2 is magnetron sputtered. The deposition set up allows several compositions of Ti-MoS2 to be deposited simultaneously, with Ti content ranging between 5 and 96 at. %, and their machining performances to be evaluated. Milling took place using a CNC Vertical Machining Center at a 877 mm/min feed rate. The effect of different coating compositional ratios on the degree of aluminium sticking when a milling insert is used to face mill an Al alloy (SAE 6061) was investigated using a combination of energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) analysis. XPS studies suggest that the greater degree of Al sticking on the rake face of the inserts is due to the formation of greater amounts of non-protective Ti-O phases. EDX mapping of the milling inserts after machining reveal that a Ti:MoS2 ratio of around 0.39 prevents Al from sticking to the tool edges. Since we prevent Al from sticking to the tool surface, the resultant machined surface finish is improved thus validating the machining performance of TiB2-coated tools using optimum compositions of Ti:MoS2 thin film coatings.
      Citation: Coatings
      PubDate: 2017-09-16
      DOI: 10.3390/coatings7090149
      Issue No: Vol. 7, No. 9 (2017)
       
  • Coatings, Vol. 7, Pages 108: Vibration Characteristics and Damping
           Analysis of the Blisk-Deposited Hard Coating Using the Rayleigh-Ritz
           Method

    • Authors: Feng Gao, Wei Sun
      First page: 108
      Abstract: For the purpose of improving the working reliability of the blisk (integrally-bladed disk) under severe environment, a passive vibration reduction method by depositing a hard coating on both sides of blades is developed and then investigated systematically. Firstly, an analytical model of the blisk-deposited hard coating is taken into account. Secondly, by using the Oberst beam theory and axial symmetry property, the composite hard-coated blade is equivalent to a special homogeneous blade possessing the equivalent material parameters. Then, energy equations of the blisk with hard-coated blades are derived by using the complex-valued modulus, and then substituted into the Lagrange equations. Additionally, eigenvalue equations of the blisk with hard-coated blades are acquired by taking advantage of Rayleigh-Ritz method, and its natural characteristics are obtained subsequently. Further, the frequency response functions of the blisk with hard-coated blades are formulated by using proportional damping to achieve its damping matrix. Finally, a stainless-steel blisk with deposited NiCoCrAlY + YSZ hard coating on both sides of the blades is chosen as the study case to conduct numerical calculations, and the results are compared with those obtained by experimental tests in terms of natural frequencies and mode shapes. The variation of natural frequencies, modal loss factors and frequency response functions of the blisk generated by hard coating are studied, respectively, and the influence of the coating thickness on the damping capacity are further discussed.
      Citation: Coatings
      PubDate: 2017-07-25
      DOI: 10.3390/coatings7080108
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 109: Fabrication and Testing of PVA/Chitosan
           Bilayer Films for Strawberry Packaging

    • Authors: Yaowen Liu, Shuyao Wang, Wenting Lan, Wen Qin
      First page: 109
      Abstract: Strawberry packaging based on four different chitosan–poly(vinylalcohol) blend films with chitosan contents of 0 wt %, 20 wt %, 25 wt %, and 30 wt % was tested. The samples were stored at 18 ± 2 °C and 60% ± 5% relative humidity for six days. Strawberry quality was evaluated during and after storage. Strawberries packaged using these films showed significant differences in weight loss and firmness, decay percentage, titratable acidity, total soluble solids, and ascorbic acid content when compared to non-packaged strawberries. The 25 wt % bilayer film showed the best performance in terms of delaying changes in strawberries. The findings suggest that these 25 wt % chitosan films can used to extend strawberry shelf lives while maintaining quality levels.
      Citation: Coatings
      PubDate: 2017-07-25
      DOI: 10.3390/coatings7080109
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 110: Phase and Microstructural Correlation of
           Spark Plasma Sintered HfB2-ZrB2 Based Ultra-High Temperature Ceramic
           Composites

    • Authors: Ambreen Nisar, Kantesh Balani
      First page: 110
      Abstract: The refractory diborides (HfB2 and ZrB2) are considered as promising ultra-high temperature ceramic (UHTCs) where low damage tolerance limits their application for the thermal protection system in re-entry vehicles. In this regard, SiC and CNT have been synergistically added as the sintering aids and toughening agents in the spark plasma sintered (SPS) HfB2-ZrB2 system. Herein, a novel equimolar composition of HfB2 and ZrB2 has shown to form a solid-solution which then allows compositional tailoring of mechanical properties (such as hardness, elastic modulus, and fracture toughness). The hardness of the processed composite is higher than the individual phase hardness up to 1.5 times, insinuating the synergy of SiC and CNT reinforcement in HfB2-ZrB2 composites. The enhanced fracture toughness of CNT reinforced composite (up to a 196% increment) surpassing that of the parent materials (ZrB2/HfB2-SiC) is attributed to the synergy of solid solution formation and enhanced densification (~99.5%). In addition, the reduction in the analytically quantified interfacial residual tensile stress with SiC and CNT reinforcements contribute to the enhancement in the fracture toughness of HfB2-ZrB2-SiC-CNT composites, mandatory for aerospace applications.
      Citation: Coatings
      PubDate: 2017-07-26
      DOI: 10.3390/coatings7080110
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 111: Thermal Analysis of Tantalum Carbide-Hafnium
           Carbide Solid Solutions from Room Temperature to 1400 °C

    • Authors: Cheng Zhang, Archana Loganathan, Benjamin Boesl, Arvind Agarwal
      First page: 111
      Abstract: The thermogravimetric analysis on TaC, HfC, and their solid solutions has been carried out in air up to 1400 °C. Three solid solution compositions have been chosen: 80TaC-20 vol % HfC (T80H20), 50TaC-50 vol % HfC (T50H50), and 20TaC-80 vol % HfC (T20H80), in addition to pure TaC and HfC. Solid solutions exhibit better oxidation resistance than the pure carbides. The onset of oxidation is delayed in solid solutions from 750 °C for pure TaC, to 940 °C for the T50H50 sample. Moreover, T50H50 samples display the highest resistance to oxidation with the retention of the initial carbides. The oxide scale formed on the T50H50 sample displays mechanical integrity to prevent the oxidation of the underlying carbide solid solution. The improved oxidation resistance of the solid solution is attributed to the reaction between Ta2O5 and HfC, which stabilizes the volume changes induced by the formation of Ta2O5 and diminishes the generation of gaseous products. Also, the formation of solid solutions disturbs the atomic arrangement inside the lattice, which delays the reaction between Ta and O. Both of these mechanisms lead to the improved oxidation resistances of TaC-HfC solid solutions.
      Citation: Coatings
      PubDate: 2017-07-28
      DOI: 10.3390/coatings7080111
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 112: Numerical Verification of Gallium Nitride
           Thin-Film Growth in a Large MOCVD Reactor

    • Authors: Chih-Kai Hu, Chun-Jung Chen, Ta-Chin Wei, Tomi T. Li, Chih-Yung Huang, Chu-Li Chao, Yi-Jiun Lin
      First page: 112
      Abstract: A numerical verification procedure and the effects of operating conditions in a large, vertical, and close-spaced reactor for metalorganic chemical vapor deposition are investigated through simulation and analysis. A set of epitaxy experiments are presented for verifying the growth rate of the gallium nitride (GaN) mechanism reported in our previous study. The full governing equations for continuity, momentum, energy, and chemical reaction are solved numerically. The results show that the real operating parameters (susceptor temperature: 1188 °C or 1238 °C; pressure: 100–300 torr) affect thin-film uniformity, and the predicted growth rates agree reasonably well with the experimental data, indicating the accuracy of the projected chemical reaction mechanisms.
      Citation: Coatings
      PubDate: 2017-07-31
      DOI: 10.3390/coatings7080112
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 113: Thermal-Sprayed Coatings on Bushing and
           Sleeve-Pipe Surfaces in Continuous Galvanizing Sinking Roller Production
           Line Applications

    • Authors: Guangwei Zhang, Deyuan Li, Ning Zhang, Nannan Zhang, Sihua Duan
      First page: 113
      Abstract: This paper describes thermal spray techniques for making hard coatings on bushing and sleeve component surfaces. Specifically, plasma-arc welding was used to produce 5-mm thick Co-Cr alloy welding overlays on the bushing, while a high-velocity oxy-fuel spraying technique and laser re-melting technique were used to produce thinner coatings of Co-Cr-Ni+WC of about 1mm thickness on the sleeve-pipe counterparts. The surface-treated components were then submerged in liquid zinc to study the corrosive behaviour of the surface coating and substrate. Both the scanning electron microscope and energy dispersive spectrometer analyses were used to study the microstructure and phase composition of both coatings and substrates prior to and after corrosion experiments. The results show that the microstructure of the bushing consists of γ-cobalt solid solution as well as the eutectic structure of γ-cobalt and carbides, which have good corrosive resistance against molten zinc. Meanwhile, the microstructure of the sleeve pipe consists of a Co-Cr solid solution with various forms of carbides, which displays the combined properties of toughness with good corrosive resistance to molten zinc.
      Citation: Coatings
      PubDate: 2017-08-02
      DOI: 10.3390/coatings7080113
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 114: Electrophoretic Coating of Octahedral
           Molybdenum Metal Clusters for UV/NIR Light Screening

    • Authors: Thi Nguyen, Benjamin Dierre, Fabien Grasset, Noée Dumait, Stéphane Cordier, Pierric Lemoine, Adèle Renaud, Hiroshi Fudouzi, Naoki Ohashi, Tetsuo Uchikoshi
      First page: 114
      Abstract: Thin and transparent Mo6 cluster films with significant optical properties were prepared on indium tin oxide (ITO)-coated glass plates from the suspension of Cs2Mo6Br14 cluster precursors dispersed in methyl-ethyl-ketone (MEK) by an electrophoretic deposition (EPD) process. Two kinds of polydimethylsiloxanes (PDMS); i.e., KF-96L-1.5CS and KF-96L-2CS corresponding to the kinetic viscosity of 1.5 and 2 centistokes, respectively, were selected to topcoat the Mo6 cluster film after the EPD. The influence of the PDMS on the durability, chemical compatibility and light absorption property of Mo6 cluster films were characterized by means of field-emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), and ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy. The stabilized PDMS-coated Mo6 cluster film could be stored for more than 6 months under ambient conditions.
      Citation: Coatings
      PubDate: 2017-08-03
      DOI: 10.3390/coatings7080114
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 115: Investigation of Structural and Electronic
           Properties of CH3NH3PbI3 Stabilized by Varying Concentrations of
           Poly(Methyl Methacrylate) (PMMA)

    • Authors: Celline Awino, Victor Odari, Thomas Sakwa
      First page: 115
      Abstract: Studies have shown that perovskites have a high potential of outdoing silicon based solar cells in terms of solar energy conversion, but their rate of degradation is also high. This study reports on improvement on the stability of CH3NH3PbI3 by passivating it with polymethylmethacrylate (PMMA). Structural and electronic properties of CH3NH3PbI3 stabilized by polymethylmethacrylate (PMMA) were investigated by varying concentrations of PMMA in the polymer solutions. Stability tests were performed over a period of time using modulated surface photovoltage (SPV) spectroscopy, X-ray diffraction (XRD), and photoluminescence (PL) measurements. The XRD patterns confirm the tetragonal structure of the deposited CH3NH3PbI3 for every concentration of PMMA. Furthermore, CH3NH3PbI3 coated with 40 mg/mL of PMMA did not show any impurity phase even after storage in air for 43 days. The Tauc gap (ETauc) determined on the basis of the in-phase SPV spectra was found in the range from 1.585 to 1.62 eV for the samples stored during initial days, but shifted towards lower energies as the storage time increased. This can be proposed to be due to different chemical reactions between CH3NH3PbI3/PMMA interfaces and air. PL intensity increased with increasing concentration of PMMA except for the perovskite coated with 40 mg/mL of PMMA. PL quenching in the perovskite coated with 40 mg/mL of PMMA can be interpreted as fast electron transfer towards the substrate in the sample. This study shows that, with an optimum concentration of PMMA coating on CH3NH3PbI3, the lifetime and hence stability on electrical and structural behavior of CH3NH3PbI3 is improved.
      Citation: Coatings
      PubDate: 2017-08-03
      DOI: 10.3390/coatings7080115
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 116: Nanoscale Characterization of Glass Flake
           Filled Vinyl Ester Anti-Corrosion Coatings

    • Authors: Salim Barbhuiya, Mohammad Choudhury
      First page: 116
      Abstract: Vinyl ester is a thermoset matrix resin that is widely used in the coating industry. The presence of glass flakes further enhances the anti-corrosion performance of this coating. This paper reports the nanoscaled characterization of glass flake filled vinyl ester anti-corrosion coatings on mild steel. Bond strength properties of one uncoated and four coated samples with different thicknesses (300, 600, 900 and 1200 μm) were studied using nanoscratch technique and ASTM Standard Test. It was found that the bond strength of coating with thickness 900 μm was the highest. The frequency distributions of elastic modulus on coating with 900 μm thickness determined using nanoindentation indicated that only 20–25% of the coating is composed of glass flakes and the balance is vinyl ester matrix. The critical depth at which the material is subject to failure due to external load and abrasion, was found to be around 100 nm.
      Citation: Coatings
      PubDate: 2017-08-04
      DOI: 10.3390/coatings7080116
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 117: Preparation and Characterization of
           Fluorinated Hydrophobic UV-Crosslinkable Thiol-Ene Polyurethane Coatings

    • Authors: Wenjing Xia, Nianqing Zhu, Rongjie Hou, Wengui Zhong, Mingqing Chen
      First page: 117
      Abstract: The polyurethane prepolymer terminated with a double bond was synthesized using isophorone diisocyanate (IPDI), hydroxyl terminated polybutadiene (HTPB), 1,4-butanediol (BDO), and 2-hydroxyethyl acrylate (HEA). Then, a series of innovative UV-curable polyurethane coatings were prepared by blending ene-terminated polyurethane, fluoroacrylate monomer, and multifunctional thiol crosslinker upon UV exposure. The incorporation of fluoroacrylate monomer and multifunctional thiols into polyurethane coatings significantly enhanced the hydrophobic property, mechanical property, pencil hardness, and glossiness of the polyurethane coatings. This method of preparing UV crosslinkable, hydrophobic polyurethane coatings based on thiol-ene chemistry exhibited numerous advantages over other UV photocuring systems.
      Citation: Coatings
      PubDate: 2017-08-06
      DOI: 10.3390/coatings7080117
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 118: Antireflection Coatings for Strongly Curved
           Glass Lenses by Atomic Layer Deposition

    • Authors: Kristin Pfeiffer, Ulrike Schulz, Andreas Tünnermann, Adriana Szeghalmi
      First page: 118
      Abstract: Antireflection (AR) coatings are indispensable in numerous optical applications and are increasingly demanded on highly curved optical components. In this work, optical thin films of SiO2, Al2O3, TiO2 and Ta2O5 were prepared by atomic layer deposition (ALD), which is based on self-limiting surface reactions leading to a uniform film thickness on arbitrarily shaped surfaces. Al2O3/TiO2/SiO2 and Al2O3/Ta2O5/SiO2 AR coatings were successfully applied in the 400–750 nm and 400–700 nm spectral range, respectively. Less than 0.6% reflectance with an average of 0.3% has been measured on a fused silica hemispherical (half-ball) lens with 4 mm diameter along the entire lens surface at 0° angle of incidence. The reflectance on a large B270 aspherical lens with height of 25 mm and diameter of 50 mm decreased to less than 1% with an average reflectance < 0.3%. The results demonstrate that ALD is a promising technology for deposition of uniform optical layers on strongly curved lenses without complex in situ thickness monitoring.
      Citation: Coatings
      PubDate: 2017-08-09
      DOI: 10.3390/coatings7080118
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 119: Microstructure, Mechanical, Oxidation and
           Corrosion Properties of the Cr-Al-Si-N Coatings Deposited by a Hybrid
           Sputtering System

    • Authors: Jicheng Ding, Tengfei Zhang, Je Yun, Myung Kang, Qimin Wang, Kwang Kim
      First page: 119
      Abstract: CrN and Cr-Al-Si-N coatings were deposited on SUS304 and Si-wafers by a hybrid coating system. The Cr and Al-Si target were connected to the cathode arc ion plating (AIP) and high power impulse magnetron sputtering (HiPIMS), respectively. Various Al and Si contents in the coatings were obtained by changing the power of Al-Si target from 0 to 1 kW. The results demonstrated a face-centered cubic structure in all of the coatings. With increasing Al-Si target power, both the density and mean diameter of the macroparticles on the coating surface declined. As Al and Si contents increased, the microstructure of the Cr-Al-Si-N coatings evolved from a dense column structure, to a finer grain column structure, and then to a compact granular-like structure. The hardness of the coatings increased from 21.5 GPa for the pure CrN coating, to a maximum value of ~27 GPa for the Cr-Al-Si-N coating deposited at 0.4 kW, which was mainly attributed to the solid solution strengthening and increased residual stress. The addition of Al and Si contents led to enhanced wear resistance against alumina balls at both room and elevated temperatures. Meanwhile, the Cr-Al-Si-N coatings also exhibited an excellent resistance to high-temperature oxidation at 800 and 1000 °C, and improved corrosion resistance, as compared with CrN coatings.
      Citation: Coatings
      PubDate: 2017-08-09
      DOI: 10.3390/coatings7080119
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 120: Development of YSZ Thermal Barrier Coatings
           Using Axial Suspension Plasma Spraying

    • Authors: Dapeng Zhou, Olivier Guillon, Robert Vaßen
      First page: 120
      Abstract: The axial injection of the suspension in the atmospheric plasma spraying process (here called axial suspension plasma spraying) is an attractive and advanced thermal spraying technology especially for the deposition of thermal barrier coatings (TBCs). It enables the growth of columnar-like structures and, hence, combines advantages of electron beam-physical vapor deposition (EB-PVD) technology with the considerably cheaper atmospheric plasma spraying (APS). In the first part of this study, the effects of spraying conditions on the microstructure of yttria partially-stabilized zirconia (YSZ) top coats and the deposition efficiency were investigated. YSZ coatings deposited on as-sprayed bond coats with 5 wt % solid content suspension appeared to have nicely-developed columnar structures. Based on the preliminary results, the nicely developed columnar coatings with variations of the stand-off distances and yttria content were subjected to thermal cycling tests in a gas burner rig. In these tests, all columnar structured TBCs showed relatively short lifetimes compared with porous APS coatings. Indentation measurements for Young’s modulus and fracture toughness on the columns of the SPS coatings indicated a correlation between mechanical properties and lifetime for the SPS samples. A simplified model is presented which correlates mechanical properties and lifetime of SPS coatings.
      Citation: Coatings
      PubDate: 2017-08-10
      DOI: 10.3390/coatings7080120
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 121: Studies on Preparation and Characterization
           of Aluminum Nitride-Coated Carbon Fibers and Thermal Conductivity of Epoxy
           Matrix Composites

    • Authors: Hyeon-Hye Kim, Youn-Sik Lee, Dong Chung, Byung-Joo Kim
      First page: 121
      Abstract: In this work; the effects of an aluminum nitride (AlN) ceramic coating on the thermal conductivity of carbon fiber-reinforced composites were studied. AlN were synthesized by a wet-thermal treatment (WTT) method in the presence of copper catalysts. The WTT method was carried out in a horizontal tube furnace at above 1500 °C under an ammonia (NH3) gas atmosphere balanced by a nitrogen using aluminum chloride as a precursor. Copper catalysts pre-doped enhance the interfacial bonding of the AlN with the carbon fiber surfaces. They also help to introduce AlN bonds by interrupting aluminum oxide (Al2O3) formation in combination with oxygen. Scanning electron microscopy (SEM); Transmission electron microscopy (TEM); and X-ray diffraction (XRD) were used to analyze the carbon fiber surfaces and structures at each step (copper-coating step and AlN formation step). In conclusion; we have demonstrated a synthesis route for preparing an AlN coating on the carbon fiber surfaces in the presence of a metallic catalyst.
      Citation: Coatings
      PubDate: 2017-08-10
      DOI: 10.3390/coatings7080121
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 122: Development of Sustainable Cold Spray
           Coatings and 3D Additive Manufacturing Components for Repair/Manufacturing
           Applications: A Critical Review

    • Authors: Sunil Pathak, Gobinda Saha
      First page: 122
      Abstract: This review article presents the findings of a comprehensive state-of-the-art literature review of the scientific and technological progress of the cold spray process in the field of repair/remanufacturing using the concept of additive manufacturing. A thorough study was conducted on the potential of this technology to form (a) both thin and thick coatings; (b) the ability to fabricate 3D freeform components in a single process, while benefiting from reduced residual stress level compared to conventional thermal spray coatings processes such as high velocity oxy-fuel (HVOF) or plasma spraying. A systematic overview of the process technology, particularly focusing on the suitability of ceramic-metallic (cermet) composite particles used as feedstock in the deposition was conducted; further elaboration was made pertinent to particle impact and bonding mechanisms during the deposition.
      Citation: Coatings
      PubDate: 2017-08-14
      DOI: 10.3390/coatings7080122
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 123: Study on Surface Properties of Polyamide 66
           Using Atmospheric Glow-Like Discharge Plasma Treatment

    • Authors: Mingyang Peng, Lee Li, Jiaming Xiong, Kui Hua, Shufan Wang, Tao Shao
      First page: 123
      Abstract: Surface modification of fiber fabric sometimes needs a large volume of cold plasma to improve its efficiency. This experimental study is based on the treatment of polyamide 66 (PA66) fabrics using large contact-area glow-like plasma, which are produced in the atmospheric air without any dielectric barriers. The atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) are adopted, respectively, to detect the surface changes in physical microstructure and the variations in the type and quantity of chemical functional groups. The results show that the PA66 fabric surface will be etched remarkably by the glow-like plasma, and the surface roughness and the surface energy are augmented. On the surface of the processed PA66 fabrics, the oxygen-containing functional groups’ content rises together with the decrease on the total primary C–C and C–N bonds. After 30 seconds of sterilization by the glow-like plasmas, most of the bacterial colonies on the fabric vanish. The effectiveness of this kind of plasma treatment could last for three days in a sealed environment.
      Citation: Coatings
      PubDate: 2017-08-14
      DOI: 10.3390/coatings7080123
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 124: Spin Coating on Spherical Surface with Large
           Central Angles

    • Authors: Huan Liu, Xudong Fang, Le Meng, Shanshan Wang
      First page: 124
      Abstract: Spin coating is one of the dominant processes for producing photoresistant thin films in integrated circuit manufacturing. The application of this process mainly focuses on flat surfaces. With the development of science and technology, the spin coating process is no longer restricted to flattened geometry. The demand for uniform thin films on curved surfaces urgently needs to be met, such as for the fabrication of anti-electromagnetic metal shielding grids on the window of fairings and grating on spherical lens. This is a challenging problem, and a fundamental mechanism is indispensable to provide guidance. However, few models have been reported about spinning a coating on curved geometry with a large central angle. To provide support for solving the problem of spin coating on a spherical surface with a large central angle, this paper presents a formulation for modeling the spin coating process on a spherical surface with a central angle close to 90 degrees and experiments that were completed to validate it. The film thickness evolution and uniformity of film thickness on a spherical surface are studied using this model and are compared with the existing literature to determine the potential advantages of the new model. Simulation results show that the uniformity of final film thickness is not ideal for uniform initial film thickness distribution. One dimensionless parameter is defined as the dominating factor to control film thickness and uniformity, which is related to the processing parameters. As demonstrated by the experimental results, this model can be adopted to predict film the thickness profile on spherical surfaces with large central angles.
      Citation: Coatings
      PubDate: 2017-08-14
      DOI: 10.3390/coatings7080124
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 125: Process Parameter Settings and Their Effect
           

    • Authors: Wolfgang Tillmann, Leif Hagen, Weifeng Luo
      First page: 125
      Abstract: Residual stresses have been a major source of concern, as they are an inevitable consequence of manufacturing and fabrication processes. The magnitude of these stresses is often as high as, or at least, comparable to the yield strength of the material. In terms of arc sprayed coatings, the utilization of bore hole drilling methods presents some practical disadvantages as mechanical parameters (Poisson’s ratio, Young’s modulus) need to be identified in order to determine the residual stress distribution. Curvature techniques using Almen strips are cost- and time-effective methods that can be used for analytical quality assurance. Within the scope of this work, a quantitative study of the amount of residual stresses induced in a twin wire arc spraying (TWAS) process for a given combination of process parameters was conducted using the incremental bore hole drilling method, as well as the curvature method including Almen strips. Therefore, the effect of the primary gas pressure, substrate preheating temperature, and handling parameters, such as the spray angle and gun velocity, which influence the coating deposition as well as the heat input into the substrate, are examined. The experiments were carried out by using an iron-based cored wire with cast tungsten carbides as filling. The results of both methods are in an acceptable accordance with each other. Different stress fields were observed depending on the parameter settings.
      Citation: Coatings
      PubDate: 2017-08-15
      DOI: 10.3390/coatings7080125
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 126: Characteristics of RF-Sputtered Thin Films of
           Calcium Phosphate on Titanium Dental Implants

    • Authors: Kuo-Yung Hung, Hong-Chen Lai, Hui-Ping Feng
      First page: 126
      Abstract: Hydroxyapatite (HA) coatings on titanium have been investigated for many years, and have demonstrated advantageous biocompatibility in dental implants. Animal experiments have demonstrated that the biological response to plasma-sprayed HA-coated implants shows disadvantages in terms of adherence, thickness uniformity, and long-term osseointegration effects. Determining how to resolve the degradation problem of HA in the body by improving osseointegration and stability in alveolar bones has become an increasingly researched topic. The present study investigated the film characteristics and dissolution properties of calcium phosphate (CaP) coatings obtained by radio-frequency (RF) sputtering of a self-developed atmospheric plasma spray (APS) HA target. The experimental parameters varied, including RF power (60–250 W), sputtering time (15–120 min), and substrate roughness (0.4–4 μm). Analyses were conducted using synchrotron X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), white light interferometry, and scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (EDS). EDS analysis showed that the Ca/P ratio increased as the discharge power was increased. The analysis results also showed that a lower surface roughness resulted in higher crystallinity, because a larger surface-free energy was attained during sputtering. In-plane texturing has been proven when HA films are sputtered onto substrates of varying roughness, within appropriate deposition parameters. FTIR analysis revealed the presence of the principal PO43- bonds in the deposited calcium phosphate films. The CaP films induced calcium phosphate precipitation when immersed in simulated body fluid (SBF), suggesting that, based on in vitro bioactive behavior, the proposed combined surface modification can be used in dental implants.
      Citation: Coatings
      PubDate: 2017-08-16
      DOI: 10.3390/coatings7080126
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 127: Investigation of Coated Cutting Tool
           Performance during Machining of Super Duplex Stainless Steels through 3D
           Wear Evaluations

    • Authors: Yassmin Seid Ahmed, Jose Paiva, Danielle Covelli, Stephen Veldhuis
      First page: 127
      Abstract: In this study, the wear mechanisms and tribological performance of uncoated and coated carbide tools were investigated during the turning of super duplex stainless steel (SDSS)—Grade UNS S32750, known commercially as SAF 2507. The tool wear was evaluated throughout the cutting tests and the wear mechanisms were investigated using an Alicona Infinite Focus microscope and a scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS). Tribo-film formation on the worn rake surface of the tool was analyzed using X-ray Photoelectron Spectroscopy (XPS). In addition, tribological performance was evaluated by studying chip characteristics such as thickness, compression ratio, shear angle, and undersurface morphology. Finally, surface integrity of the machined surface was investigated using the Alicona microscope to measure surface roughness and SEM to reveal the surface distortions created during the cutting process, combined with cutting force analyses. The results obtained showed that the predominant wear mechanisms are adhesion and chipping for all tools investigated and that the AlTiN coating system exhibited better performance in all aspects when compared with CVD TiCN + Al2O3 coated cutting insert and uncoated carbide insert; in particular, built-up edge formation was significantly reduced.
      Citation: Coatings
      PubDate: 2017-08-17
      DOI: 10.3390/coatings7080127
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 128: Uncertainty of the X-ray Diffraction (XRD)
           sin2 ψ Technique in Measuring Residual Stresses of Physical Vapor
           Deposition (PVD) Hard Coatings

    • Authors: Quanshun Luo, Shicai Yang
      First page: 128
      Abstract: Residual stresses of physical vapor deposition (PVD) hard coatings can be measured using X-ray diffraction (XRD) methods under either conventional d-sin2 ψ mode or glancing incident (GIXRD) mode, in which substantial uncertainties exist depending on the applied diffraction parameters. This paper reports systematic research on the effect of the two analytical modes, as well as the anisotropic elastic modulus, on the measured residual stress values. A magnetron sputtered TiN grown on hardened tool steel was employed as the sample coating, to measure its residual stress using various diffraction peaks from {111} to {422} acquired at a range of incident glancing angles from 2° to 35°. The results were interpreted in terms of the effective X-ray penetration depth, which has been found to be determined predominantly by the incident glancing angle. In the d-sin2 ψ mode, the results present an approximate residual stress over a depth of effective X-ray penetration, and it is recommended to use a diffraction peak of high-index lattice plane from {311} to {422}. The GIXRD mode helps determine a depth profile of residual stress, since the measured residual stress depends strongly on the X-ray penetration. In addition, the anisotropy of elastic modulus shows limited influence on the calculated residual stress value.
      Citation: Coatings
      PubDate: 2017-08-20
      DOI: 10.3390/coatings7080128
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 129: The Use of Triboemission Imaging and Charge
           Measurements to Study DLC Coating Failure

    • Authors: Alessandra Ciniero, Julian Le Rouzic, Tom Reddyhoff
      First page: 129
      Abstract: We present a study on the simultaneous evolution of the electron emission and surface charge accumulation that occurs during scratching tests in order to monitor coating failure. Steel discs coated with a diamond-like-carbon (DLC) film were scratched in both vacuum (~10−5 Torr) and atmospheric conditions, with electron emission and surface charge being measured by a system of microchannel plates and an electrometer, respectively. The results highlight a positive correlation between emission intensity values, surface charge measurements and surface damage topography, suggesting the effective use of these techniques to monitor coating wear in real time.
      Citation: Coatings
      PubDate: 2017-08-20
      DOI: 10.3390/coatings7080129
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 130: Influence of Grit-Blasting and Hydrofluoric
           Acid Etching Treatment on Surface Characteristics and Biofilm Formation on
           Zirconia

    • Authors: Aifang Han, James Tsoi, Jukka Matinlinna, Zhuofan Chen
      First page: 130
      Abstract: The objective of this study was to investigate the effect of hydrofluoric acid etching treatment on the surface characteristics of zirconia and Streptococcus sanguinis (S. sanguinis) and Porphyromonas gingivalis (P. gingivalis) biofilm formation on zirconia. Zirconia specimens were prepared with different treatments, including being polished with 1000-grit SiC abrasive paper as the control group (Group C), grit-blasted with 110 μm silica-coated alumina particles (Group GB), etched with 40% hydrofluoric acid for 25 min at 100 °C (Group HF), and grit-blasted with 110 μm silica-coated alumina particles and then etched with 40% hydrofluoric acid for 25 min at 100 °C (Group GBHF). The highest surface roughness values and hydrophilicity were shown in Group HF and Group GBHF. Scanning electron microscopy (SEM) showed that hydrofluoric acid can create a crater-like appearance on the zirconia surface. An energy-dispersive X-ray (EDX) analysis demonstrated similar element concentration (wt %) in Group C, Group HF, and Group GBHF, but not for Group GB with higher concentrations of Al and Si element. Colony forming unit (CFU) counts showed that a similar amount of S. sanguinis biofilm and significantly lower P. gingivalis biofilm were formed on zirconia surfaces in Group HF and Group GBHF compared to that in Group C after three days of bacteria culture (p < 0.05). These results indicate that hydrofluoric acid etching on zirconia may not increase S. sanguinis and P. gingivalis mature biofilm formation on zirconia.
      Citation: Coatings
      PubDate: 2017-08-20
      DOI: 10.3390/coatings7080130
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 131: A Study of CO2 Laser Treatment on Colour
           Properties of Cotton-Based Fabrics

    • Authors: On-na Hung, Chi-wai Kan
      First page: 131
      Abstract: In this study, laser was applied to two types of cotton-based woven fabrics in order to study the effect of CO2 laser technology on colour and fabric strength properties. The woven fabrics had different fibre compositions, i.e., one was 100% cotton while the other had 60% cotton blended with 40% polyester. They were treated with different combinations of laser processing parameters, i.e., resolution (52, 60, and 68 dpi) and pixel time (110, 120, 130, and 140 μs). There were two approaches adopted: (1) laser treated and then dyed (LD); and (2) first dyed and then laser treated (DL), in order to study the effects of the two different sequences on the resultant colour. Colour properties include reflectance value, colour yield, CIE L*a*b* values and levelness measured by spectrophotometer; pH value and tensile strength were also measured. It was discovered that laser treatment had no influence on chromaticity of cotton fabrics. Moreover, fabrics treated with laser had a lighter shade than the control samples. This confirmed that both approaches, i.e., laser treatment conducted before and after dyeing, can provide a colour fading effect. The tensile strength of fabrics was affected differently in relation to the dyeing and laser process. According to results obtained from the pH measurement, it is confirmed that laser treatment can provide a colour fading effect without affecting the pH value, and the fabrics can be used instantly right after the laser treatment.
      Citation: Coatings
      PubDate: 2017-08-20
      DOI: 10.3390/coatings7080131
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 132: Directional Trans-Planar and Different
           In-Plane Water Transfer Properties of Composite Structured Bifacial
           Fabrics Modified by a Facile Three-Step Plasma Treatment

    • Authors: Fengxin Sun, Zhiqiang Chen, Licheng Zhu, Zhaoqun Du, Xungai Wang, Maryam Naebe
      First page: 132
      Abstract: Fabrics with moisture management properties are strongly expected to benefit various potential applications in daily life, industry, medical treatment and protection. Here, a bifacial fabric with dual trans-planar and in-plane liquid moisture management properties was reported. This novel fabric was fabricated to have a knitted structure on one face and a woven structure on the other, contributing to the different in-plane water transfer properties of the fabric. A facile three-step plasma treatment was used to enrich the bifacial fabric with asymmetric wettability and liquid absorbency. The plasma treated bifacial fabric allowed forced water to transfer from the hydrophobic face to hydrophilic face, while it prevented water to spread through the hydrophobic face when water drops were placed on the hydrophilic face. This confirmed one-way water transport capacity of the bifacial fabric. Through the three-step plasma treatment, the fabric surface was coated with a Si-containing thin film. This film contributed to the hydrophobic property, while the physical properties of the fabrics such as stiffness and color were not affected. This novel fabric can potentially be used to design and manufacture functional and smart textiles with tunable moisture transport properties.
      Citation: Coatings
      PubDate: 2017-08-22
      DOI: 10.3390/coatings7080132
      Issue No: Vol. 7, No. 8 (2017)
       
  • Coatings, Vol. 7, Pages 84: Corrosion Protection of Steel by
           Epoxy-Organoclay Nanocomposite Coatings

    • Authors: Domna Merachtsaki, Panagiotis Xidas, Panagiotis Giannakoudakis, Konstantinos Triantafyllidis, Panagiotis Spathis
      First page: 84
      Abstract: The purpose of the present work was to study the corrosion behavior of steel coated with epoxy-(organo) clay nanocomposite films. The investigation was carried out using salt spray exposures, optical and scanning electron microscopy examination, open circuit potential, and electrochemical impedance measurements. The mechanical, thermomechanical, and barrier properties of pristine glassy epoxy polymer and epoxy-clay nanocomposites were examined. The degree of intercalation/exfoliation of clay nanoplatelets within the epoxy polymer also was determined. The mechanical, thermomechanical, and barrier properties of all the epoxy-clay nanocomposites were improved compared to those of the pristine epoxy polymer. In addition, both the pristine epoxy and the epoxy nanocomposite coatings protected the steel from corrosion. Furthermore, the protective properties of the nanocomposite coatings were superior compared to those of the pristine epoxy polymer. The protective properties of the nanocomposite coatings varied with the modified clay used. The epoxy-montmorillonite clay modified with primary octadecylammonium ions, Nanomer I.30E, had a better behavior than that modified with quaternary octadecylammonium ions, Nanomer I.28E.
      PubDate: 2017-06-22
      DOI: 10.3390/coatings7070084
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 85: Oxidation Behavior and Mechanism of Al4SiC4 in
           MgO-C-Al4SiC4 System

    • Authors: Huabai Yao, Xinming Xing, Enhui Wang, Bin Li, Junhong Chen, Jialin Sun, Xinmei Hou
      First page: 85
      Abstract: Al4SiC4 powder with high purity was synthesized using the powder mixture of aluminum (Al), silicon (Si), and carbon (C) at 1800 °C in argon. Their oxidation behavior and mechanism in a MgO-C-Al4SiC4 system was investigated at 1400–1600 °C. XRD, SEM, and energy dispersive spectrometry (EDS) were adopted to analyze the microstructure and phase evolution. The results showed that the composition of oxidation products was closely related to the atom diffusion velocity and the compound oxide layer was generated on Al4SiC4 surface. In addition, the effect of different CO partial pressure on the oxidation of Al4SiC4 crystals was also studied by thermodynamic calculation. This work proves the great potential of Al4SiC4 in improving the MgO-C materials.
      PubDate: 2017-06-23
      DOI: 10.3390/coatings7070085
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 86: Silica-Based Sol-Gel Coating on Magnesium
           Alloy with Green Inhibitors

    • Authors: Vinod Upadhyay, Zachary Bergseth, Brett Kelly, Dante Battocchi
      First page: 86
      Abstract: In this work, the performances of several natural organic inhibitors were investigated in a sol-gel system (applied on the magnesium alloy Mg AZ31B substrate). The inhibitors were quinaldic acid (QDA), betaine (BET), dopamine hydrochloride (DOP), and diazolidinyl urea (DZU). Thin, uniform, and defect-free sol-gel coatings were prepared with and without organic inhibitors, and applied on the Mg AZ31B substrate. SEM and EDX were performed to analyze the coating surface properties, the adhesion to the substrate, and the thickness. Electrochemical measurements, including electrochemical impedance spectroscopy (EIS) and anodic potentiodynamic polarization scan (PDS), were performed on the coated samples to characterize the coatings’ protective properties. Also, hydrogen evolution measurement—an easy method to measure magnesium corrosion—was performed in order to characterize the efficiency of coating protection on the magnesium substrate. Moreover, scanning vibrating electrode technique (SVET) measurements were performed to examine the efficiency of the coatings loaded with inhibitors in preventing and containing corrosion events in defect areas. From the testing results it was observed that the formulated sol-gel coatings provided a good barrier to the substrate, affording some protection even without the presence of inhibitors. Finally, when the inhibitors’ performances were compared, the QDA-doped sol-gel was able to contain the corrosion event at the defect.
      PubDate: 2017-06-22
      DOI: 10.3390/coatings7070086
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 87: Effect of Cold-Spray Conditions Using a
           Nitrogen Propellant Gas on AISI 316L Stainless Steel-Coating
           Microstructures

    • Authors: Shinichiro Adachi, Nobuhiro Ueda
      First page: 87
      Abstract: Cold-spray techniques have been a significant development for depositing metal coatings in recent years. In cold-spray processes, inexpensive nitrogen gas is widely used as the propellant gas in many industries. However, it is difficult to produce austenitic stainless steel coatings with dense microstructures with cold-spray techniques when using nitrogen propellant gas because of work hardening. In this study, the effects of cold-spray conditions using a nitrogen propellant gas on AISI 316L stainless steel coatings were examined. It was found that a higher nitrogen propellant gas temperature and pressure produce coatings with dense microstructures. The measured AISI 316L coating hardness values suggest that AISI 316L particles sprayed at temperatures of 700 and 800 °C soften due to the heat, allowing uniform deformation on the substrate and consequently forming dense coating microstructures. In addition, AISI 316L powder with particle diameters of 5–20 µm resulted in a denser coating microstructure than powder with particle diameters of 10–45 and 20–53 µm. Finally, the standoff distance between the nozzle and the substrate also affected the AISI 316L coating microstructures; a standoff distance of 40 mm produced the densest microstructure.
      PubDate: 2017-06-28
      DOI: 10.3390/coatings7070087
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 88: Barrier Heights of Au on Diamond with
           Different Terminations Determined by X-ray Photoelectron Spectroscopy

    • Authors: Fengnan Li, Jingwen Zhang, Xiaoliang Wang, Minghui Zhang, Hongxing Wang
      First page: 88
      Abstract: Barrier heights of Au on hydrogen-/oxygen-/fluorine-/nitrogen-terminated diamond (H-/O-/F-/N-diamond) have been investigated by X-ray photoelectron spectroscopy. All of the H-/O-/F-/N-diamond surfaces have been formed on different areas of one diamond sample. An Au film with a thickness of 4 nm was evaporated to form Au/diamond contacts. Barrier height values for Au on H-/O-/F-/N-diamond contacts were determined to be −0.19, 1.71, 2.29, and 2.39 eV, respectively. Then, the surface of Au/diamond contacts was treated by 1000 eV Ar+ bombardment with different duration of time, resulting in a pinned barrier height of 1.83 eV independent of contact structures. In the end, the spatial distribution of the energy band diagram has been calculated by solving Poisson’s equation.
      PubDate: 2017-06-29
      DOI: 10.3390/coatings7070088
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 89: Ultra-Low Reflectivity Anti-Reflection Coating
           on a Plastic Cover Slip in Liquid for He-Ne Laser Light

    • Authors: Jin-Cherng Hsu, Heng-Ying Cho, Tsang-Yen Hsieh, Jyh-Liang Wang
      First page: 89
      Abstract: An ultra-low anti-reflection optical coating on both surfaces of a plastic cover slip was studied for use in confocal image measurements. The optical reflectance at a wavelength of 632.8 nm was less than 0.1% when the coated sample was placed in a liquid having a refractive index of 1.34, close to the aqueous solution of the biomaterial. The high- and low-index coating films, Substance-2 (PrTiO3) and silicon dioxide (SiO2), were measured by an ellipsometer to determine their optical refraction indices and extinction coefficients. Theoretically, when the two layer thicknesses are designed using the optical admittance diagram of the cover slip to approach the equivalent index of 1.34, a reflectance of 1.6 × 10−5% in the liquid could be obtained. Experimentally, the reflectance of the sample deposited on the two faces of the cover slip was 4.223 ± 0.145% as measured in the air; and 0.050 ± 0.002% as measured by a He-Ne laser in the liquid.
      PubDate: 2017-06-29
      DOI: 10.3390/coatings7070089
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 90: Concrete Damage in Field Conditions and
           Protective Sealer and Coating Systems

    • Authors: Md. Safiuddin
      First page: 90
      Abstract: Concrete structures undergo different forms of damage during their service life. The aim of this study is to identify the most common forms of concrete damage in field conditions. A number of concrete elements and structures were visually inspected and the damage was photographed. The damage phenomena covered are delamination, popout, spalling, scaling, drying shrinkage cracking, corrosion-induced cracking, map cracking, rust and salt stains, discoloration, and mold and moss growths. The probable reasons for these damage phenomena are discussed in this study. Moreover, this study highlights how concrete structures can be protected from the aforementioned forms of damage by using sealer and coating systems as surface treatments. Different sealer and coating systems, emphasizing their selection for specific uses, installation on concrete substrate, effects on concrete durability, performance criteria, and performance evaluation methods have been discussed. Furthermore, some recommendations are given to improve the performance of concrete sealer and coating systems for the protection of concrete structures in field conditions.
      PubDate: 2017-06-29
      DOI: 10.3390/coatings7070090
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 91: Application of FEM to Estimate
           Thermo-Mechanical Properties of Plasma Sprayed Composite Coatings

    • Authors: Rodolphe Bolot, Delphine Aussavy, Ghislain Montavon
      First page: 91
      Abstract: The presence of defects such as voids, inter-lamellar porosities or cracks causes a decrease in the effective thermal conductivity of plasma-sprayed coatings as well as a decrease in corresponding mechanical properties, such as the Young’s modulus. In general, the effective properties of thermal spray coatings are thus very different from that of bulk materials and thus have to be quantified to validate in service performances. A complementary approach allowing us to understand the relationships between the microstructure of a coating and its macro-properties is that of Finite Element Modeling (FEM). The case of composite coatings is more complicated still, due to the presence of different materials. In the present study, thermo-mechanical properties of a plasma-sprayed composite coating were estimated by numerical modeling based on FEM. The method applied uses directly cross-sectional micrographs without simplification, using a one-cell per pixel approach. Characteristics such as the thermal conductivity, the Young’s modulus, the Poisson’s ratio and the dilatation coefficient were considered. The example selected was an AlSi/polyester coating used as an abradable seal in the aerospace industry.
      PubDate: 2017-06-30
      DOI: 10.3390/coatings7070091
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 92: Effect of Si3N4 Addition on Oxidation
           Resistance of ZrB2-SiC Composites

    • Authors: Manab Mallik, Kalyan Ray, Rahul Mitra
      First page: 92
      Abstract: The oxidation behavior of ZrB2-20 vol % SiC and ZrB2-20 vol % SiC-5 vol % Si3N4 composites prepared by hot-pressing and subjected to isothermal exposure at 1200 or 1300 °C for durations of 24 or 100 h in air, as well as cyclic exposure at 1300 °C for 24 h, have been investigated. The oxidation resistance of the ZrB2-20 vol % SiC composite has been found to improve by around 20%–25% with addition of 5 vol % Si3N4 during isothermal or cyclic exposures at 1200 or 1300 °C. This improvement in oxidation resistance has been attributed to the formation of higher amounts of SiO2 and Si2N2O, as well as a greater amount of continuity in the oxide scale, because these phases assist in closing the pores and lower the severity of cracking by exhibiting self-healing type behavior. For both the composites, the mass changes are found to be higher during cyclic exposure at 1300 °C by about 2 times compared to that under isothermal conditions.
      PubDate: 2017-06-30
      DOI: 10.3390/coatings7070092
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 93: Investigation on the Cathodic Protection
           Effect of Low Pressure Cold Sprayed AlZn Coating in Seawater via Numerical
           Simulation

    • Authors: Guosheng Huang, Xiaodan Lou, Hongren Wang, Xiangbo Li, Lukuo Xing
      First page: 93
      Abstract: Cold spray can deposit a composite coating simply by spraying mechanically-mixed Al and Zn powders, while no quantitative data has been reported on the anti-corrosion performance of different composite cold-sprayed coatings. In the present work, the finite element method was used to estimate the cathodic protection effect by simulating the potential distribution on a damaged cold-sprayed AlZn coating on Q235 steel. The results indicate that AlZn coating can only provide a limiting cathodic protection for substrate, because it can only polarize a very narrow zone negative to −0.78 V (vs. SCE, saturated calomel electrode). The remaining area of the steel substrate still has a very high residual corrosion rate. Computational methods can be used to predict the corrosion rate of AlZn coating, and the simulation results were validated by the results of a weight loss experiment.
      PubDate: 2017-07-04
      DOI: 10.3390/coatings7070093
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 94: Study on the Preparation of a High-Efficiency
           Carbon Fiber Dissipating Coating

    • Authors: Jing Li, Xue Li, Chunlei Fan, Huan Yao, Xuyang Chen, Yeming Liu
      First page: 94
      Abstract: The working temperature of electronic components directly determines their service life and stability. In order to ensure normal operation of electronic components, cooling the coating is one of the best ways to solve the problem. Based on an acrylic amino-resin system, a dissipating coating was prepared with carbon fiber (CF) as the main thermal conductive filler. The influence of the CF content on the thermal conductivity was determined by the single factor method. The surface structure was observed by scanning electron microscopy (SEM). The results show: With the increase of the CF mass fraction, both the heat dispersion and heat conduction coefficient of the coating tend to increase at first and then decrease, and the heat dissipation effect is optimum when the CF mass fraction is 12.3 wt %. At this point, the coating shows an excellent comprehensive performance, such as 1st level adhesion, H grade hardness, and thermal conductivity of 1.61 W/m·K. Furthermore, this paper explored the radiating mechanism of coating in which CF produces a coating which forms a heat “channel” for rapid heat conduction. When the optimal value is exceeded, the cooling effect is reduced because of the accumulation and the anisotropy of CF.
      PubDate: 2017-07-04
      DOI: 10.3390/coatings7070094
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 95: The Effect of Deposition Parameters on the
           Growth Rate of Microcrystalline Diamond Powders Synthesized by HFCVD
           Method

    • Authors: Tao Zhang, Ye Zou
      First page: 95
      Abstract: Conventional diamond powders (<10 μm) are generally produced from crushing large-sized diamonds synthesized by high-pressure and high-temperature (HPHT) technique, whereas they have many morphological imperfections. In the present work, these powders are served as diamond seeds and regrown by hot filament chemical vapor deposition (HFCVD). Deposition parameters—such as the carbon concentration, substrate temperature, and bias current—which play a determined role in the homoepitaxial growth rate of micron diamonds, are investigated in their respective usual ranges. As shown in the experimental results, under the preconditions of maintaining the good morphology of crystals and inhibiting polycrystal growth, the growth rate of isolated diamond crystals can be controlled at 0.9 μm/h. Besides, the final improved powders have a wide range of particle sizes, which could fail to meet the requirements for commercial powders without the post-process of sieving.
      PubDate: 2017-07-06
      DOI: 10.3390/coatings7070095
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 96: Polymerization of PEDOT/PSS/Chitosan-Coated
           Electrodes for Electrochemical Bio-Sensing

    • Authors: Li Sui, Bingshu Zhang, Jun Wang, Ainan Cai
      First page: 96
      Abstract: Poly(3,4-ethylenedioxythiophene) (PEDOT) doped with poly (styrene sulfonate) (PSS) has a variety of chemical and biomedical applications. Additionally, chitosan has been extensively used in industrial and medical fields. However, whether chitosan could be incorporated into conducting polymers of PEDOT/PSS is not clear. In this study, the PEDOT/PSS/chitosan coatings were electrochemically polymerized on the surface of 0.5 mm platinum (Pt) electrodes and the properties of electrochemical cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) of the PEDOT/PSS/chitosan-coated electrodes were investigated. Furthermore, PEDOT/PSS/chitosan-coated electrodes used for electrochemical bio-sensing, using dexamethasone (Dex) as a model bio-sensing material, were examined. The results demonstrated that PEDOT/PSS/chitosan-coated electrodes were stable in phosphate-buffered saline (PBS) solution. The electrochemical CV curve areas, reflecting the charge delivery capacity, and the EIS of the PEDOT/PSS/chitosan-coated electrodes were sensitive to Dex, and the good linearity can be obtained between CV curve areas, the EIS and the concentration of Dex. In addition, electrochemical sensitivity of the PEDOT/PSS/chitosan-coated electrodes to Dex was much higher than ultraviolet (UV) spectroscopy detection. All these results revealed that the PEDOT/PSS/chitosan-coated electrodes can be electrochemical polymerized and used for electrochemical bio-sensing.
      PubDate: 2017-07-06
      DOI: 10.3390/coatings7070096
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 97: Technological Strategies to Preserve Burrata
           Cheese Quality

    • Authors: Cristina Costa, Annalisa Lucera, Amalia Conte, Angelo Zambrini, Matteo Del Nobile
      First page: 97
      Abstract: Burrata cheese is a very perishable product due to microbial proliferation and undesirable sensory changes. In this work, a step-by-step optimization approach was used to design proper processing and packaging conditions for burrata in brine. In particular, four different steps were carried out to extend its shelf life. Different headspace gas compositions (MAP-1 30:70 CO2:N2; MAP-2 50:50 CO2:N2 and MAP-3 65:35 CO2:N2) were firstly tested. To further promote product preservation, a coating was also optimized. Then, antimicrobial compounds in the filling of the burrata cheese (lysozyme and Na2-EDTA) and later in the coating (enzymatic complex and silver nanoparticles) were analyzed. To evaluate the quality of the samples, in each step headspace gas composition, microbial population, and pH and sensory attributes were monitored during storage at 8 ± 1 °C. The results highlight that the antimicrobial compounds in the stracciatella, coating with silver nanoparticles, and packaging under MAP-3 represent effective conditions to guarantee product preservation, moving burrata shelf life from three days (control sample) to ten days.
      Citation: Coatings
      PubDate: 2017-07-09
      DOI: 10.3390/coatings7070097
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 98: Influence of Process Parameters on High
           Velocity Oxy-Fuel Sprayed Cr3C2-25%NiCr Coatings

    • Authors: Mingxiang Xie, Yue Lin, Peng Ke, Shuoyu Wang, Shihong Zhang, Zhicheng Zhen, Liangshui Ge
      First page: 98
      Abstract: In this work, the Cr3C2-25% NiCr powder was deposited on stainless steel with different combustion pressures and powder feed rates using HVOF technique. The microstructure, porosity, micro-hardness, indentation fracture toughness, adhesion strength, and wear resistance at 500 °C of the coatings were investigated. The results showed that HVOF sprayed Cr3C2-25% NiCr coatings possessed low porosity, high micro-hardness, and enough adhesion strength. The powder feed rate had obvious effect on porosity, micro-hardness and indention fracture toughness of the coatings, and the coating sprayed under the powder feed rate of 33.5 g/min possessed the optimal performance. The wear tests illustrated that the HVOF sprayed Cr3C2-25NiCr coating possessed good wear resistance at the temperature of 500 °C, in which the coating sprayed at the powder feed rate of 33.5 g/min had the best wear resistance due to its dense structure and enough fracture toughness.
      Citation: Coatings
      PubDate: 2017-07-09
      DOI: 10.3390/coatings7070098
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 99: Progress in Wear Resistant Materials for Total
           Hip Arthroplasty

    • Authors: Rohit Khanna, Joo Ong, Ebru Oral, Roger Narayan
      First page: 99
      Abstract: Current trends in total hip arthroplasty (THA) are to develop novel artificial hip joints with high wear resistance and mechanical reliability with a potential to last for at least 25–30 years for both young and old active patients. Currently used artificial hip joints are mainly composed of femoral head of monolithic alumina or alumina-zirconia composites articulating against cross-linked polyethylene liner of acetabular cup or Co-Cr alloy in a self-mated configuration. However, the possibility of fracture of ceramics or its composites, PE wear debris-induced osteolysis, and hypersensitivity issue due to metal ion release cannot be eliminated. In some cases, thin ultra-hard diamond-based, TiN coatings on Ti-6A-4V or thin zirconia layer on the Zr-Nb alloy have been fabricated to develop high wear resistant bearing surfaces. However, these coatings showed poor adhesion in tribological testing. To provide high wear resistance and mechanical reliability to femoral head, a new kind of ceramic/metal artificial hip joint hybrid was recently proposed in which 10–15 μm thick dense layer of pure α-alumina was formed onto Ti-6Al-4V alloy by deposition of Al metal layer by cold spraying or cold metal transfer methods with 1–2 μm thick Al3Ti reaction layer formed at their interface to improve adhesion. An optimal micro-arc oxidation treatment transformed Al to dense α-alumina layer, which showed high Vickers hardness 1900 HV and good adhesion to the substrate. Further tribological and cytotoxicity analyses of these hybrids will determine their efficacy for potential use in THA.
      Citation: Coatings
      PubDate: 2017-07-09
      DOI: 10.3390/coatings7070099
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 100: Electrodeposition of Vanadium Oxides at Room
           Temperature as Cathodes in Lithium-Ion Batteries

    • Authors: Michalis Rasoulis, Dimitra Vernardou
      First page: 100
      Abstract: Electrodeposition of vanadium pentoxide coatings was performed at room temperature and a short growth period of 15 min based on an alkaline solution of methanol and vanadyl (III) acetyl acetonate. All samples were characterized by X-ray diffraction, Raman spectroscopy, field-emission scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. The current density and electrolyte concentration were found to affect the characteristics of the as-grown coatings presenting enhanced crystallinity and porous structure at the highest values employed in both cases. The as-grown vanadium pentoxide at current density of 1.3 mA·cm−2 and electrolyte concentration of 0.5 M indicated the easiest charge transfer of Li+ across the vanadium pentoxide/electrolyte interface presenting a specific discharge capacity of 417 mAh·g−1, excellent capacitance retention of 95%, and coulombic efficiency of 94% after 1000 continuous Li+ intercalation/deintercalation scans. One may then suggest that this route is promising to prepare large area vanadium pentoxide electrodes with excellent stability and efficiency at very mild conditions.
      Citation: Coatings
      PubDate: 2017-07-12
      DOI: 10.3390/coatings7070100
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 101: Chemical Vapor Deposition of TaC/SiC on
           Graphite Tube and Its Ablation and Microstructure Studies

    • Authors: Suresh Kumar, Samar Mondal, Anil Kumar, Ashok Ranjan, Namburi Prasad
      First page: 101
      Abstract: Tantalum carbide (TaC) and silicon carbide (SiC) layers were deposited on a graphite tube using a chemical vapor deposition process. Tantalum chloride (TaCl5) was synthesized in situ by reacting tantalum chips with chlorine at 550 °C. TaC was deposited by reacting TaCl5 with CH4 in the presence of H2 at 1050–1150 °C and 50–100 mbar. SiC was deposited at 1000 °C using methyl-tri-chloro-silane as a precursor at 50 mbar. At 1150 °C; the coating thickness was found to be about 600 μm, while at 1050 °C it was about 400 μm for the cumulative deposition time of 10 h. X-ray diffraction (XRD) and X-ray Photo-Electron Spectroscopy (XPS) studies confirmed the deposition of TaC and SiC and their phases. Ablation studies of the coated specimens were carried out under oxyacetylene flame up to 120 s. The coating was found to be intact without surface cracks and with negligible erosion. The oxide phase of TaC (TaO2 and Ta2O5) and the oxide phase of SiC (SiO2) were also found on the surface, which may have protected the substrate underneath from further oxidation.
      Citation: Coatings
      PubDate: 2017-07-13
      DOI: 10.3390/coatings7070101
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 102: Ti-SLActive and TiZr-SLActive Dental Implant
           Surfaces Promote Fast Osteoblast Differentiation

    • Authors: Milena Kaluđerović, Tamara Krajnović, Danijela Maksimović-Ivanić, Hans-Ludwig Graf, Sanja Mijatović
      First page: 102
      Abstract: A primary goal in modern surface modification technology of dental implants is to achieve biocompatible surfaces with rapid but controlled healing which also allow health and longevity of implants. In order to realize all, understanding of osseointegration phenomena is crucial. Although Ti-SLA, Ti-SLActive and TiZr-SLActive surfaces have been successfully used in clinical implantology and were shown to notably reduce the primary healing time, available in vitro studies are sparse and do not concern or explore the mechanism(s) involved in human osteoblast behavior on these surfaces. Ti-SLA, Ti-SLActive, TiZr-SLActive, Ti cp, Ticer and Cercon surfaces were used. Osteoblast proliferation, cell cluster formation, morphological changes, induction of autophagy, nitric oxide (NO), reactive oxygen species/reactive nitrogen species (ROS/RNS) formation, osteocalcin (OC), bone sialoprotein (BSP) and collagen type I (Col-1) affected by various surfaces were analyzed. These surfaces induced formation of mature osteoblasts caused by elevated oxidative stress (ROS) followed by overexpression of osteoblast maturation key molecule (NO), with different intensity however. These mature osteoblasts induced upregulation of OC, BSP and Col-1, activating PI3/Akt signalling pathway resulting in autophagy, known as an important process in differentiation of osteoblast cells. Additional distinctive subpopulation identified on Ticer, Ti-SLA (after 5 days), Ti-SLActive and TiZr-SLActive surfaces (after 2 days) were forming cell clusters, essential for bone noduli formation and mineralisation. The results suggest that Ti- and TiZr-SLActive possess advanced properties in comparison with Ticer and Ti-SLA manifested as accelerated osteoblast differentiation. These effects could explain already known fast osseointegration of these surfaces in vivo.
      Citation: Coatings
      PubDate: 2017-07-15
      DOI: 10.3390/coatings7070102
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 103: Reduced-Order Modeling for and Vibration
           Characteristics Analysis of a Hard-Coated Mistuned Blisk

    • Authors: Feng Gao, Wei Sun
      First page: 103
      Abstract: This paper develops a damping strategy for the vibration reduction of a mistuned bladed disk (blisk) by depositing hard coating on its blades, and systematically investigates the vibration characteristics of the hard-coated mistuned (HCM) blisk. By using an improved fixed-interface component modal synthesis method (fixed-ICMSM), a reduced-order model (ROM) of the HCM blisk is established. Then, based on the proposed ROM, solutions of eigenvalue equations are carried out to obtain the natural frequencies and mode shapes. Further, modal loss factors and a damping matrix of the HCM blisk are achieved by taking advantage of the modal strain energy method and the proportional damping model, respectively. Moreover, the frequency response function of the HCM blisk, which can exhibit dynamic behaviors, was deduced. Finally, a mistuned blisk with a deposited NiCoCrAlY + YSZ hard coating on both sides of the blades is chosen as a study case to conduct a finite element analysis, and the results are compared with those obtained from the experimental test in terms of natural frequencies and mode shapes. The variation of the natural frequencies, the modal loss factors, and the frequency response function generated by the NiCoCrAlY + YSZ hard coating are studied, and the influence of coating area on damping capacity is further discussed.
      Citation: Coatings
      PubDate: 2017-07-18
      DOI: 10.3390/coatings7070103
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 104: Enhancing Dark Shade Pigment Dyeing of Cotton
           Fabric Using Plasma Treatment

    • Authors: Chi-Wai Kan, Wai-Shan Man
      First page: 104
      Abstract: This study is intended to investigate the effect of atmospheric pressure plasma treatment on dark shade pigment dyeing of cotton fabric. Experimental results reveal that plasma-treated cotton fabric can attain better color yield, levelness, and crocking fastness in dark shade pigment dyeing, compared with normal cotton fabric (not plasma treated). SEM analysis indicates that cracks and grooves were formed on the cotton fiber surface where the pigment and the binder can get deposited and improve the color yield, levelness, and crocking fastness. It was also noticed that pigment was aggregated when deposited on the fiber surface which could affect the final color properties.
      Citation: Coatings
      PubDate: 2017-07-19
      DOI: 10.3390/coatings7070104
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 105: Preparation of Hydroxyapatite/Tannic Acid
           Coating to Enhance the Corrosion Resistance and Cytocompatibility of AZ31
           Magnesium Alloys

    • Authors: Bowu Zhu, Shimeng Wang, Lei Wang, Yang Yang, Jun Liang, Baocheng Cao
      First page: 105
      Abstract: Hydroxyapatite/tannic acid coating (HA/TA) were prepared on AZ31 magnesium alloys (AZ31) via chemical conversion and biomimetic methods. The characterization and properties of the coating were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), corrosion testing, MC3T3-E1 cell proliferation assay, and MC3T3-E1 cell morphology observation. The results showed that tannic acid as an inducer increased the number of nucleation centers of hydroxyapatite and rendered the morphology more uniform. Compared to bare AZ31 magnesium (Mg) alloys (Ecorr = −1.462 ± 0.006 V, Icorr = (4.8978 ± 0.2455) × 10−6 A/cm2), the corrosion current density of the HA/TA-coated magnesium alloys ((5.6494 ± 0.3187) × 10−8 A/cm2) decreased two orders of magnitude, and the corrosion potential of the HA/TA-coated Mg alloys (Ecorr = −1.304 ± 0.006 V) increased by about 158 mV. This indicated that the HA/TA coating was effectively protecting the AZ31 against corrosion in simulated body fluid (SBF). Cell proliferation assays and cell morphology observations results showed that the HA/TA coating was not toxic to the MC3T3-E1 cells.
      Citation: Coatings
      PubDate: 2017-07-20
      DOI: 10.3390/coatings7070105
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 106: Particle Characterisation and Depletion of
           Li2CO3 Inhibitor in a Polyurethane Coating

    • Authors: Anthony Hughes, James Laird, Chris Ryan, Peter Visser, Herman Terryn, Arjan Mol
      First page: 106
      Abstract: The distribution and chemical composition of inorganic components of a corrosion-inhibiting primer based on polyurethane is determined using a range of characterisation techniques. The primer consists of a Li2CO3 inhibitor phase, along with other inorganic phases including TiO2, BaSO4 and Mg-(hydr)oxide. The characterisation techniques included particle induced X-ray and γ-ray emission spectroscopies (PIXE and PIGE, respectively) on a nuclear microprobe, as well as SEM/EDS hyperspectral mapping. Of the techniques used, only PIGE was able to directly map the Li distribution, although the distribution of Li2CO3 particles could be inferred from SEM through using backscatter contrast and EDS. Characterisation was also performed on a primer coating that had undergone leaching in a neutral salt spray test for 500 h. Overall, it was found that Li2CO3 leaching resulted in a uniform depletion zone near the surface, but also much deeper local depletion, which is thought to be due to the dissolution of clusters of Li2CO3 particles that were connected to the external surface/electrolyte interface.
      Citation: Coatings
      PubDate: 2017-07-21
      DOI: 10.3390/coatings7070106
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 107: The Dispersion Tolerance of Micro/Nano
           Particle in Polydimethylsiloxane and Its Influence on the Properties of
           Fouling Release Coatings Based on Polydimethylsiloxane

    • Authors: Miao Ba, Zhanping Zhang, Yuhong Qi
      First page: 107
      Abstract: Particles can be used to improve the mechanical properties of fouling release coatings based on polydimethylsiloxane (PDMS). In this study, coatings were prepared by high speed stirring using seven types of particles, with different particle size from nanometer to micrometer. The influence of specific surface area of the particles on the dispersion tolerance was investigated. The results showed that the dispersion tolerance of particles in PDMS decreased with the increase in specific surface area of the particle, and for nano particles, the factor most affecting the dispersion tolerance was the specific surface area of agglomerate particle. Subsequently, the surface properties, mechanical properties, and biofilm adhesion assay of coatings were investigated. Results indicated that surface roughness increased with the increase of dispersion tolerance. Surface roughness of samples improved the hydrophobicity of samples, yet the polar chemical group of nano silica and fumed silica reduced the hydrophobicity of samples. Further, particles could enhance the mechanical properties of coating, especially nano particles. Compared to the coating without particle, biofilm adhesion performance of coating with particles decreased, which was determined by the increase of the elastic modulus and surface roughness of coatings.
      Citation: Coatings
      PubDate: 2017-07-21
      DOI: 10.3390/coatings7070107
      Issue No: Vol. 7, No. 7 (2017)
       
  • Coatings, Vol. 7, Pages 72: Ammonia Generation via a Graphene-Coated
           Nickel Catalyst

    • Authors: Fei Lu, Gerardine Botte
      First page: 72
      Abstract: A novel graphene-coated Ni electrode was developed in this investigation to improve corrosion resistance while unexpectedly enhancing the ammonia generation rate in the electrochemically induced urea to ammonia (eU2A) process, which is an electrochemical onsite ammonia generation method. The development of the electrode is crucial for the eU2A reactions since in the ammonia generation process, the concentration of ammonia is inevitably high on the surface of the electrode, leading to severe corrosion of the electrode and the loss of generated ammonia as well. In this paper, the graphene was derived from raw coal by using the chemical vapor deposition method and self-lifted onto a Ni electrode to form a protective layer for corrosion prevention. Transmission electron microscopy showed the synthesized graphene had few-layers and Raman spectroscopy indicated that the coating of graphene was stable during the eU2A reaction. As a result, the ammonia corrosion of the Ni electrode was dramatically reduced by ~20 times with the graphene coating method. More importantly, a higher ammonia generation rate (~2 times) was achieved using the graphene-coated Ni working electrode compared to a bare Ni electrode in the eU2A process.
      PubDate: 2017-05-27
      DOI: 10.3390/coatings7060072
      Issue No: Vol. 7, No. 6 (2017)
       
  • Coatings, Vol. 7, Pages 73: Combustion Synthesis of UHTC Composites from
           Ti–B4C Solid State Reaction with Addition of VIb Transition Metals

    • Authors: Chun-Liang Yeh, Wei-Zuo Lin
      First page: 73
      Abstract: UHTC composites were prepared by self-propagating high-temperature synthesis (SHS) from the Ti–B4C reaction system with addition of Cr, Mo, and W. The starting sample composition was formulated as (3−x)Ti + B4C + xMe with x = 0.1–1.0 and Me = Cr, Mo, or W. For all samples conducted in this study, self-sustaining combustion was well established and propagated with a distinct reaction front. With no addition of Cr, Mo, or W, solid state combustion of the 3Ti + B4C sample featuring a combustion front temperature (Tc) of 1766 °C and a combustion wave velocity (Vf) of 16.5 mm/s was highly exothermic and produced an in situ composite of 2TiB2 + TiC. When Cr, Mo, or W was adopted to replace a portion of Ti, the reaction exothermicity was lowered, and hence, a significant decrease in Tc (from 1720 to 1390 °C) and Vf (from 16.1 to 3.9 mm/s) was observed. With addition of Cr, Mo, and W, the final products were CrB-, MoB-, and WB-added TiB2–TiC composites. The absence of CrB2, MoB2, and WB2 was attributed partly to the loss of boron from thermal decomposition of B4C and partly to lack of sufficient reaction time inherent to the SHS process.
      PubDate: 2017-06-01
      DOI: 10.3390/coatings7060073
      Issue No: Vol. 7, No. 6 (2017)
       
  • Coatings, Vol. 7, Pages 74: Fabrication of Luminescent Antireflective
           Coatings with CaMoO4:Eu3+/Ag Composite Structure

    • Authors: Kazuhiro Matsumoto, Manabu Hagiwara, Shinobu Fujihara
      First page: 74
      Abstract: Highly transparent and luminescent CaMoO4:Eu3+/Ag composite films were fabricated on glass substrates as multifunctional antireflective (AR) coatings. The films were deposited through a combination of a sol–gel dip-coating technique and a hot water treatment. With the addition of an aluminum source in coating solutions, the sol–gel-derived films underwent a remarkable microstructural change during the hot water treatment due to the reaction between an amorphous alumina phase and water. This change brought both an antireflective effect (suppression of Fresnel reflection) and luminescence enhancement (suppression of total internal reflection) to the films. The introduction of Ag nanoparticles into the films further increased luminescence intensity without losing the antireflective effect.
      PubDate: 2017-06-02
      DOI: 10.3390/coatings7060074
      Issue No: Vol. 7, No. 6 (2017)
       
  • Coatings, Vol. 7, Pages 75: Surface Erosion of Low-Current Reed Switches

    • Authors: Igor Zeltser, Aleksey Karpov, Evgeny Moos, Nikolay Rybin, Alexander Tolstoguzov
      First page: 75
      Abstract: The erosion model of the surface coatings of reed switches considering different physicochemical processes occurring on the contact surfaces and inside the inter-electrode gap was proposed. According to that, the discrete electron avalanche (ecton) introduced in the explosive electron emission theory by Mesyats is considered as the main motive force responsible for the surface modification and mass transfer of materials in the course of breaking/shorting of the contacts. By means of SEM imaging and energy dispersive X-ray microanalysis of the contact surfaces after various numbers of switching cycles, the energy threshold of the ecton generation defining the erosion stability of the coatings was found to be proportional to the specific sublimation and ionization energies of coating materials. It has been shown that the total erosion of the coatings on the working surface of the contacts after the commutation test possess the resultant character; i.e., the specificities of erosion occurring after each commutation event are characteristic for the whole of the commutation test. In further development of our model, we suggested that a few monolayers of metals (or alloys) with low ionization potential deposited on the main coatings can improve the erosion stability of contacts.
      PubDate: 2017-06-03
      DOI: 10.3390/coatings7060075
      Issue No: Vol. 7, No. 6 (2017)
       
  • Coatings, Vol. 7, Pages 76: Alternative Fillers for the Production of
           Bituminous Mixtures: A Screening Investigation on Waste Powders

    • Authors: Cesare Sangiorgi, Piergiorgio Tataranni, Francesco Mazzotta, Andrea Simone, Valeria Vignali, Claudio Lantieri
      First page: 76
      Abstract: There has been a significant increase in the demand for using recycled materials in construction because of the lack and limitation of available natural resources. A number of industrial and domestic waste products are being used in the replacement of traditional materials for road construction, and many studies have been carried out in recent years on the use of different recycled materials in substitution of conventional fillers in Asphalt Concretes (AC). The aim of this laboratory research is to analyze the physical characteristics of three different recycled fillers and compare them with those of a traditional limestone filler. The alternative fillers presented in this paper are: a waste bleaching clay that comes from two consecutive stages in the industrial process for decolouring vegetable oils and producing biogas (Ud filler), a dried mud waste from a tungsten mine (MW filler) and a recycled glass powder (Gl filler). Results show significant differences between the fillers, and, in particular, Rigden Voids (RV) seem to have the largest potential influence on the rheology of ACs.
      PubDate: 2017-06-03
      DOI: 10.3390/coatings7060076
      Issue No: Vol. 7, No. 6 (2017)
       
  • Coatings, Vol. 7, Pages 77: Optimization of the Laser Hardening Process by
           Adapting the Intensity Distribution to Generate a Top-hat Temperature
           Distribution Using Freeform Optics

    • Authors: Fritz Klocke, Martin Schulz, Stefan Gräfe
      First page: 77
      Abstract: Laser hardening is a surface hardening process which enables high quality results due to the controllability of the energy input. The hardened area is determined by the heat distribution caused by the intensity profile of the laser beam. However, commonly used top-hat laser beams do not provide an ideal temperature profile. Therefore, in this paper the beam profile, and thus the temperature profile, is optimized using freeform optics. The intensity distribution is modified to generate a top-hat temperature profile on the surface. The results of laser hardening with the optimized distribution are thereupon compared with results using a top-hat intensity distribution.
      PubDate: 2017-06-07
      DOI: 10.3390/coatings7060077
      Issue No: Vol. 7, No. 6 (2017)
       
  • Coatings, Vol. 7, Pages 78: Mn-Promoted Growth and Photoluminescence of
           Molybdenum Disulphide Monolayer

    • Authors: Shengzhong Jin, Shichao Zhao, Jiaxin Weng, Yanfei Lv
      First page: 78
      Abstract: Molybdenum disulphide (MoS2) monolayer is a two-dimensional semiconductor material with potential applications in nano electronic devices. However, it is still a challenge to reproducibly synthesize single layer MoS2 in high quality. Herein, we report the growth of monolayer of MoS2 on the SiO2/Si substrate with manganese heterogeneous nucleation. It was shown that the Mn promotes the growth of monolayer MoS2 via heterogeneous nucleation. The growth temperature range expanded two-fold, the nucleation density increased as well. The monolayer prepared in the presence of Mn exhibits a unique red emission peak at 732 nm at room temperature compared to the sample in the absence of Mn.
      PubDate: 2017-06-08
      DOI: 10.3390/coatings7060078
      Issue No: Vol. 7, No. 6 (2017)
       
  • Coatings, Vol. 7, Pages 79: Nitrogen Trapping Ability of Hydrogen-Induced
           Vacancy and the Effect on the Formation of AlN in Aluminum

    • Authors: Duy Vo, Aleksey Lipnitskii, Truong Nguyen, Thoi Nguyen
      First page: 79
      Abstract: This paper presents the ternary interaction of N, H, and vacancy point defects and the nitrogen trapping ability of aluminum vacancies induced by hydrogen by means of DFT methods employed in VASP (Vienna Ab initio Simulation Package) and Abinit packages. The obtained vacancy formation energy of 0.65 eV is close to experimental values. Although the N–vacancy complex is unstable with the negative binding energy of −0.51 eV, the stability of H–vacancy–N is proved by the positive binding energy of 0.59 eV and the appearance of the orbital hybridization in the density of state (DOS) of atoms connecting to this complex. Moreover, Al vacancies can trap more than 4 N atoms, which prevents the formation of aluminum nitride and subsequently affects not only the hardness of the Al surface but also many practical applications of AlN coating.
      PubDate: 2017-06-09
      DOI: 10.3390/coatings7060079
      Issue No: Vol. 7, No. 6 (2017)
       
  • Coatings, Vol. 7, Pages 80: Development of a TiC/Cr23C6 Composite Coating
           on a 304 Stainless Steel Substrate through a Tungsten Inert Gas Process

    • Authors: Behzad Heidarshenas, Ghulam Hussain, Mohammed. Asmael
      First page: 80
      Abstract: The aim of this study was to develop a composite coating on 304 stainless steel employing a TIG (tungsten inert gas) process. Ti wire cored with graphite powder was used as the means of coating material. The process parameters were controlled to develop a coating with optimum characteristics (i.e., hardness and wear resistance). The microstructure of the coating was analyzed with SEM and XRD. It was found that both the hardness and the wear resistance increase as the current increases, while both of these properties decrease as travelling speed increases. It was found that the coated samples with composite layers were harder than the substrate and can range up to 1100 HV, almost 4.5 times higher than the hardness of 304 stainless steel. Likewise, the wear resistance of the coating was observed to be 4.5 times higher than that of the substrate. The high performance of the coating, as revealed by microstructural analysis, was due to the formation of TiC and Cr23C6.The optimum conditions for producing the coating are thus proposed to include a 120 A current and a 3.17 mm/s travel speed.
      PubDate: 2017-06-14
      DOI: 10.3390/coatings7060080
      Issue No: Vol. 7, No. 6 (2017)
       
  • Coatings, Vol. 7, Pages 81: Maximum Deformation Ratio of Droplets of
           Water-Based Paint Impact on a Flat Surface

    • Authors: Weiwei Xu, Jianfei Luo, Jun Qin, Yongming Zhang
      First page: 81
      Abstract: In this research, the maximum deformation ratio of water-based paint droplets impacting and spreading onto a flat solid surface was investigated numerically based on the Navier–Stokes equation coupled with the level set method. The effects of droplet size, impact velocity, and equilibrium contact angle are taken into account. The maximum deformation ratio increases as droplet size and impact velocity increase, and can scale as We1/4, where We is the Weber number, for the case of the effect of the droplet size. Finally, the effect of equilibrium contact angle is investigated, and the result shows that spreading radius decreases with the increase in equilibrium contact angle, whereas the height increases. When the dimensionless time t* < 0.3, there is a linear relationship between the dimensionless spreading radius and the dimensionless time to the 1/2 power. For the case of 80° ≤ θe ≤ 120°, where θe is the equilibrium contact angle, the simulation result of the maximum deformation ratio follows the fitting result. The research on the maximum deformation ratio of water-based paint is useful for water-based paint applications in the automobile industry, as well as in the biomedical industry and the real estate industry. Please check all the part in the whole passage that highlighted in blue whether retains meaning before.
      PubDate: 2017-06-19
      DOI: 10.3390/coatings7060081
      Issue No: Vol. 7, No. 6 (2017)
       
  • Coatings, Vol. 7, Pages 82: Functionalized Textile Based Therapy for the
           Treatment of Atopic Dermatitis

    • Authors: Wenyi Wang, Patrick Hui, Chi-Wai Kan
      First page: 82
      Abstract: Atopic dermatitis (AD) is a common chronic inflammatory skin condition characterized by intense puritus and skin dryness. The pathogenesis for AD has not been fully understood to date. Complementary therapies are very popular as effective treatment for AD among clinical practitioners. This study presents a comprehensive review of published works associated with textiles-based complementary therapies for AD treatment such as wet-wrap dressing, functionalized textiles, and the application of hydrogel techniques in the textile industry to provide a better understanding of the development and design of new textiles-based transdermal therapies.
      PubDate: 2017-06-17
      DOI: 10.3390/coatings7060082
      Issue No: Vol. 7, No. 6 (2017)
       
  • Coatings, Vol. 7, Pages 83: Aluminizing via Ionic Liquid Electrodeposition
           and Pack Cementation: A Comparative Study with Inconel 738 and a CoNiCrAlY
           

    • Authors: Luca Tagliaferri, Enrico Berretti, Andrea Giaccherini, Stefano M. Martinuzzi, Francesco Bozza, Martin Thoma, Ugo Bardi, Stefano Caporali
      First page: 83
      Abstract: A novel aluminizing process based upon room temperature Al-electrodeposition from Ionic Liquids followed by diffusion heat treatment was applied on bare- and CoNiCrAlY-coated Inconel 738 (IN738). The aluminized samples were tested by isothermal oxidation at 1000 °C in air. The microstructural and chemical evolution of the samples were determined as function of oxidation time and compared with the currently applied coatings obtained via pack cementation. The newly proposed method is suitable for the CoNiCrAlY coating, but not for the bare IN738. In the latter, the formed Al-enriched layer is much thinner and the anticorrosion properties resulted in being reduced. This is probably due to the presence of precipitates, which slow down the aluminum inward diffusion impairing the formation of a well-developed interdiffusion zone (IDZ). Traces of the electrolyte, embedded during the Al-electrodeposition process, can be seen as the origin of these precipitates.
      PubDate: 2017-06-19
      DOI: 10.3390/coatings7060083
      Issue No: Vol. 7, No. 6 (2017)
       
  • Coatings, Vol. 7, Pages 57: Theoretical Studies of the Adsorption and
           Migration Behavior of Boron Atoms on Hydrogen-Terminated Diamond (001)
           Surface

    • Authors: Xuejie Liu, Congjie Kang, Haimao Qiao, Yuan Ren, Xin Tan, Shiyang Sun
      First page: 57
      Abstract: The adsorption and migration activation energies of boron atoms on a hydrogen-terminated diamond (001) surface were calculated using first principles methods based on density functional theory. The values were then used to investigate the behavior of boron atoms in the deposition process of B-doped diamond film. On the fully hydrogen-terminated surface, the adsorption energy of a boron atom is relatively low and the maximum value is 1.387 eV. However, on the hydrogen-terminated surface with one open radical site or two open radical sites, the adsorption energy of a boron atom increases to 4.37 eV, and even up to 5.94 eV, thereby forming a stable configuration. When a boron atom deposits nearby a radical site, it can abstract a hydrogen atom from a surface carbon atom, and then form a BH radical and create a new radical site. This study showed that the number and distribution of open radical sites, namely, the adsorption of hydrogen atoms and the abstraction of surface hydrogen atoms, can influence the adsorption and migration of boron atoms on hydrogen-terminated diamond surfaces.
      PubDate: 2017-04-27
      DOI: 10.3390/coatings7050057
      Issue No: Vol. 7, No. 5 (2017)
       
  • Coatings, Vol. 7, Pages 58: Field Evaluation of Red-Coloured Hot Mix
           Asphalt Pavements for Bus Rapid Transit Lanes in Ontario, Canada

    • Authors: Qingfan Liu, Sina Varamini, Susan Tighe
      First page: 58
      Abstract: Coloured pavements have been implemented by metropolitan areas to denote dedicated lanes for bus rapid transit to maintain a high level of safety. Transit benefits of these installations are well documented. However, field performance of various types of coloured pavement has not been investigated systematically, with questions not being answered. In collaboration with the Regional Municipality of York (ON, Canada) where red pavement sections have been in operation for years for its bus rapid transit lanes, the Centre for Pavement and Transportation Technology at the University of Waterloo (Waterloo, ON, Canada) assessed the performance of various types of red pavements including epoxy paint and red asphalt mixes. It was found that, with significant lower texture depth, epoxy paint surface has disadvantages to red asphalt pavement from a pavement texture and safety perspective. The red asphalt sections in this study were observed as lower yet compatible frictional levels to conventional black pavement. Various types of contamination onto the red pavement were observed during field survey. In addition, the ultraviolet radiation degraded the colour of red asphalt pavement over time and may make it less effective for lane designation. Long-term monitoring is recommended to evaluate the functional and structural performance of red asphalt pavement.
      PubDate: 2017-04-26
      DOI: 10.3390/coatings7050058
      Issue No: Vol. 7, No. 5 (2017)
       
  • Coatings, Vol. 7, Pages 59: Ride Quality Due to Road Surface
           Irregularities: Comparison of Different Methods Applied on a Set of Real
           Road Profiles

    • Authors: Giuseppe Loprencipe, Pablo Zoccali
      First page: 59
      Abstract: Road roughness evaluation can be carried out using different approaches. Among these, the assessment of ride quality level perceived by road users is one of the most-used. In this sense, different evaluation methods have been developed in order to link the level of irregularities present on road surface profiles with the induced detrimental effects in terms of discomfort. In particular, relationships between wavelength content of road profiles and consequent level of comfort perceived had been investigated by using, in general, a mean panel ratings approach. In this paper, four ride quality evaluation methods (Ride Number, Michigan Ride Quality Index (RQI), Minnesota Ride Quality Index and frequency-weighted vertical acceleration, awz, according to ISO 2631 were applied to a set of real road profiles. The obtained results were analyzed, investigating a possible relation between the different indices, comparing them also with the most-used road roughness method worldwide: the International Roughness Index (IRI). The analyses carried out in this work have highlighted how the various rating scales may lead to a different ride quality assessment of the same road pavements. Furthermore, comparing the awz with the values obtained for the other three methods, it was found that their rating scales are set for speeds within the range 80–100 km/h. For this reason, it is necessary to identify new thresholds to be applied for lower speeds, as in the case of urban roads. In this sense, the use of the ISO 2631 approach would seem to be a useful tool.
      PubDate: 2017-04-26
      DOI: 10.3390/coatings7050059
      Issue No: Vol. 7, No. 5 (2017)
       
  • Coatings, Vol. 7, Pages 60: Water and Oil Repellent Finishing of Textiles
           

    • Authors: Franco Ferrero, Monica Periolatto, Lorenzo Tempestini
      First page: 60
      Abstract: In this work, various textile fabrics were coated with silicone and fluorocarbon-based resins by photo-curing using ultraviolet irradiation. A great number of large fabric samples were impregnated by padding with commercial finishing agents and then irradiated in air with a high power, semi-industrial UV source. The add-on of various finishing agents was kept low to reduce the treatment cost. White and dyed samples of different textile composition were treated and evaluated in terms of conferred repellency, yellowing, or color changes. Most relevant process parameters were investigated, utilizing the thermal process normally adopted at industrial level as reference. The results were statistically evaluated by ANOVA using Minitab 16 software, in order to identify the most influential parameters and to evaluate the real possibility of replacing the thermal treatment with UV curing.
      PubDate: 2017-04-26
      DOI: 10.3390/coatings7050060
      Issue No: Vol. 7, No. 5 (2017)
       
  • Coatings, Vol. 7, Pages 61: Kinetic Analysis of Additive on Plasma
           Electrolytic Boriding

    • Authors: Yongfeng Jiang, Yefeng Bao, Min Wang
      First page: 61
      Abstract: Plasma electrolytic boriding (PEB) is a method of combination surface strengthening and surface texturing on metal. In this study, the kinetics and the lubrication friction of borided layers in the plasma electrolytic boriding on the Q235 were investigated in an aqueous solution for 5–15 min. The cross-section and surface morphologies of the boriding layers were confirmed using scanning electron microscope (SEM). The presence of phases on the surface was determined using the X-ray diffraction. The hardness and the lubrication friction were evaluated using a micro-hardness tester and pin-on-disk friction tester in an oil sliding condition, respectively. The PEB layer contains phases in FeB, Fe2B, Ni3B4, NiB, and Ni2B. It is indicated that the value of activation energy in the PEB treatment is approximately 186.17 kJ/mol. The random micro-pores in surface texturing are unevenly distributed on the surface of the Q235. The micro-hardness of the boriding layer is up to 900 HV, whereas that of the substrate is approximately 181 HV. The weight loss of PEB sample in 10 min is 0.0017 mg in the lubrication friction, whereas that of untreated sample is 0.0047 mg in the same condition. The formation of boriding strengthening surface texturing in PEB improves lubrication friction greatly.
      PubDate: 2017-04-28
      DOI: 10.3390/coatings7050061
      Issue No: Vol. 7, No. 5 (2017)
       
  • Coatings, Vol. 7, Pages 62: An All Sol-Gel Process for the Heteroepitaxial
           Growth of YBa2Cu3O7−x/LaNiO3/YBa2Cu3O7−x Tri-layer

    • Authors: Chuanbao Wu, Gaoyang Zhao, Po Fang, Shasha Wang, Ye Zhang
      First page: 62
      Abstract: The preparation of a YBa2Cu3O7−x/LaNiO3/YBa2Cu3O7−x sandwich structured film on a LaAlO3 (100) substrate by a sol-gel method was investigated. YBa2Cu3O7−x/LaNiO3/YBa2Cu3O7−x tri-layer heterostructures with different epitaxial characteristics can be deposited by controlling the heat treatment temperature. X-ray diffraction and transmission electron microscopy results show that the bottom YBCO film grows epitaxially on the LaAlO3 substrate along the c axis, and that this epitaxial growth trend is extended to the subsequently deposited LaNiO3 film. For this reason, the LaNiO3 film also grows epitaxially along the c axis. Furthermore, this epitaxial growth trend is extended to the top YBa2Cu3O7−x film, yielding YBa2Cu3O7−x/LaNiO3/YBa2Cu3O7−x tri-layer heterostructures with epitaxial growth characteristics along the c axis, which enables both the bottom and top YBa2Cu3O7−x layers to possess superconducting abilities.
      PubDate: 2017-04-28
      DOI: 10.3390/coatings7050062
      Issue No: Vol. 7, No. 5 (2017)
       
  • Coatings, Vol. 7, Pages 63: Fabrication of Photovoltaic Textiles

    • Authors: Robert Mather, John Wilson
      First page: 63
      Abstract: Solar photovoltaic (PV) arrays are providing an increasing fraction of global electrical demand, with an accelerating rate of new installations. Most of these employ conventional glass-fronted panels, but this type of PV array does not satisfy applications that require a light-weight, flexible PV generator. An option discussed in this article is to consider textiles for such solar cell substrates. As explained in this review, combining the choice of PV cell type with the choice of textile offers alternative structures for flexible PV cells. In particular, the relative advantages and disadvantages are contrasted, either forming PV-coated fibres into a fabric, or coating an already formed fabric with the PV materials. It is shown that combining thin-film amorphous silicon PV technology and woven polyester fabric offers one solution to realizing flexible fabric PV cells, using well-understood coating methods from the textile and semiconductor industries. Finally a few applications are presented that are addressed by this approach.
      PubDate: 2017-04-29
      DOI: 10.3390/coatings7050063
      Issue No: Vol. 7, No. 5 (2017)
       
  • Coatings, Vol. 7, Pages 64: Strain Effects by Surface Oxidation of Cu3N
           Thin Films Deposited by DC Magnetron Sputtering

    • Authors: Abhijit Majumdar, Steffen Drache, Harm Wulff, Arun Mukhopadhyay, Satyaranjan Bhattacharyya, Christiane Helm, Rainer Hippler
      First page: 64
      Abstract: We report the self-buckling (or peeling off) of cubic Cu3N films deposited by DC magnetron sputtering of a Cu target in a nitrogen environment at a gas pressure of 1 Pa. The deposited layer partially peels off as it is exposed to ambient air at atmospheric pressure, but still adheres to the substrate. The chemical composition of the thin film as investigated by means of X-ray photoelectron spectroscopy (XPS) shows a considerable surface oxidation after exposure to ambient air. Grazing incidence X-ray diffraction (GIXRD) confirms the formation of a crystalline Cu3N phase of the quenched film. Notable are the peak shifts in the deposited film to smaller angles in comparison to stress-free reference material. The X-ray pattern of Cu3N exhibits clear differences in the integral width of the line profiles. Changes in the film microstructure are revealed by X-ray diffraction, making use of X-ray line broadening (Williamson–Hall and Stokes–Fourier/Warren–Averbach method); it indicates that the crystallites are anisotropic in shape and show remarkable stress and micro-strain.
      PubDate: 2017-04-29
      DOI: 10.3390/coatings7050064
      Issue No: Vol. 7, No. 5 (2017)
       
  • Coatings, Vol. 7, Pages 65: A Specified Procedure for Distress
           Identification and Assessment for Urban Road Surfaces Based on PCI

    • Authors: Giuseppe Loprencipe, Antonio Pantuso
      First page: 65
      Abstract: In this paper, a simplified procedure for the assessment of pavement structural integrity and the level of service for urban road surfaces is presented. A sample of 109 Asphalt Concrete (AC) urban pavements of an Italian road network was considered to validate the methodology. As part of this research, the most recurrent defects, those never encountered and those not defined with respect to the list collected in the ASTM D6433 have been determined by statistical analysis. The goal of this research is the improvement of the ASTM D6433 Distress Identification Catalogue to be adapted to urban road surfaces. The presented methodology includes the implementation of a Visual Basic for Application (VBA) language-based program for the computerization of Pavement Condition Index (PCI) calculation with interpolation by the parametric cubic spline of all of the density/deduct value curves of ASTM D6433 distress types. Also, two new distress definitions (for manholes and for tree roots) and new density/deduct curve values were proposed to achieve a new distress identification manual for urban road pavements. To validate the presented methodology, for the 109 urban pavements considered, the PCI was calculated using the new distress catalogue and using the ASTM D6433 implemented on PAVERTM. The results of the linear regression between them and their statistical parameters are presented in this paper. The comparison of the results shows that the proposed method is suitable for the identification and assessment of observed distress in urban pavement surfaces at the PCI-based scale.
      PubDate: 2017-04-30
      DOI: 10.3390/coatings7050065
      Issue No: Vol. 7, No. 5 (2017)
       
  • Coatings, Vol. 7, Pages 66: Fatigue and Healing Properties of Low
           Environmental Impact Rubberized Bitumen for Asphalt Pavement

    • Authors: Ayad Subhy, Davide Lo Presti
      First page: 66
      Abstract: The addition of recycled tyre rubber as a modifier to enhance the mechanical properties of bitumen has proven to provide asphalt mixtures with better mechanical performance. However the rubberised bitumen presents the limitation of requiring higher manufacturing and compaction temperatures. This could be solved by subjecting the tyre rubber to sort of pre-treatments such as: Adding warm-mix additives and/or using partial devulcanisation. These solutions have the potential of lowering the overall environmental impact of the asphalt pavement, however it is still not clear whether these can be detrimental for the rubberized asphalt binder mechanical properties. This paper investigates the effect on fatigue and healing properties of rubberized bitumen blended with pre-treated crumb rubber. An innovative combined fatigue and healing analysis will be presented and used to compare the several rubberised binders with a neat bitumen. The analysis consists in conducting time sweep tests by means of dynamic shear rheometer, by applying repeated cycles of stress or strain loading at selected temperatures and loading frequency. The healing potential of binders was evaluated by introducing short rest periods after a certain number of load pulses. At last, the unique energy parameter obtained using the Ratio of Dissipated Energy Change approach, was applied to obtain a unique index that could provide combined information for both fatigue binder damage and healing phenomenon. The results showed that the analysed rubberised bitumens show having better fatigue and healing performance when compared to the straight-run bitumen.
      PubDate: 2017-05-05
      DOI: 10.3390/coatings7050066
      Issue No: Vol. 7, No. 5 (2017)
       
  • Coatings, Vol. 7, Pages 67: Characterization of the Anti-Graffiti
           Properties of Powder Organic Coatings Applied in Train Field

    • Authors: Stefano Rossi, Michele Fedel, Simone Petrolli, Flavio Deflorian
      First page: 67
      Abstract: The widespread prevalence of the phenomenon of graffiti and the growth of the removal cost—in particular in public transport systems—has pushed the research for technical solutions to this problem. Suitable solutions to address graffiti-related concerns are needed in order to reduce the cleaning costs as well as the downtime of trains. Graffiti are a big problem for painted metal, because the protective coatings and graffiti have the same chemical nature (polymeric matter). A permanent coating is expected to be able to resist the highest possible number of cleanings of the graffiti without modifying its aesthetic and corrosion protection properties. The purpose of this study is to develop a methodological approach for the characterization of graffiti-resistant organic coatings. For this purpose, a critical review of the existing standards is carried out. The anti-graffiti properties of a polyurethane organic coating were investigated before and after accelerated weathering. In order to understand the behavior of the coatings during cleaning, the aging of the coating in contact with the remover was carried out. The effect on the corrosion protection properties was assessed during the accelerated aging. The resistance of the coating was proved to be strongly affected by the surface finishing. UV exposure modified surface properties and graffiti removal efficiency.
      PubDate: 2017-05-06
      DOI: 10.3390/coatings7050067
      Issue No: Vol. 7, No. 5 (2017)
       
  • Coatings, Vol. 7, Pages 68: Stiffness of Plasma Sprayed Thermal Barrier
           Coatings

    • Authors: Shiladitya Paul
      First page: 68
      Abstract: Thermal spray coatings (TSCs) have complex microstructures and they often operate in demanding environments. Plasma sprayed (PS) thermal barrier coating (TBC) is one such ceramic layer that is applied onto metallic components where a low macroscopic stiffness favors stability by limiting the stresses from differential thermal contraction. In this paper, the Young’s modulus of TBC top coat, measured using different techniques, such as four-point bending, indentation and impulse excitation is reported, along with a brief description of how the techniques probe different length scales. Zirconia-based TBC top coats were found to have a much lower global stiffness than that of dense zirconia. A typical value for the as-sprayed Young’s modulus was ~23 GPa, determined by beam bending. Indentation, probing a local area, gave significantly higher values. The difference between the two stiffness values is thought to explain the wide range of TBC top coat Young’s modulus values reported in the literature. On exposure to high temperature, due to the sintering process, detached top coats exhibit an increase in stiffness. This increase in stiffness caused by the sintering of fine-scale porosity has significant impact on the strain tolerance of the TBC. The paper discusses the different techniques for measuring the Young’s modulus of the TBC top coats and implications of the measured values.
      PubDate: 2017-05-09
      DOI: 10.3390/coatings7050068
      Issue No: Vol. 7, No. 5 (2017)
       
  • Coatings, Vol. 7, Pages 69: Influence of Heating Conditions for Formation
           of a Thin Apatite Film on Zirconia Using a Molecular Precursor Method

    • Authors: Masatsugu Hirota, Chihiro Mochizuki, Mitsunobu Sato, Tohru Hayakawa
      First page: 69
      Abstract: The influence of heating conditions, heating temperature, and heating time on the formation of a thin carbonate-containing hydroxyapatite (CA) film onto partially stabilized zirconia using a molecular precursor method was evaluated. The molecular precursor solution was prepared from a mixture of calcium-ethylenediaminetetraacetic acid complex and phosphate compounds at Ca/P ratio of 1.67. After the application of molecular precursor solution onto zirconia, four different heating conditions—namely, 600 °C-2 h, 800 °C-2 h, 1000 °C-2 h, and 600 °C-4 h—were applied. No distinct difference of surface appearance of CA coating was observed between 600 and 800 °C-2 h. Fusion of apatite crystals was observed at 1000 °C-2 h. Surface roughness of CA film at 1000 °C-2 h was significantly higher than those under other heating conditions. Heating at 800 °C produced a significantly more hydrophilic surface and higher degree of crystallization. No significant differences were recognized in the critical load at the first crack in the coating among the four samples by scratch tests. After 30 days’ immersion in phosphate buffered saline, the four different CA coating films were still present. Simulated body fluid immersion experiments were performed as in vitro biocompatibility tests. After 48 h immersion, the CA film at 800 °C-2 h showed a greater amount of spherical crystal precipitation. It was suggested that properties of CA coating on partially stabilized zirconia using a molecular precursor method were influenced by the heating temperature and time.
      PubDate: 2017-05-09
      DOI: 10.3390/coatings7050069
      Issue No: Vol. 7, No. 5 (2017)
       
  • Coatings, Vol. 7, Pages 70: A New Finite Element Formulation for Nonlinear
           Vibration Analysis of the Hard-Coating Cylindrical Shell

    • Authors: Yue Zhang, Wei Sun, Jian Yang
      First page: 70
      Abstract: In this paper, a four-node composite cylindrical shell finite element model based on Love’s first approximation theory is proposed to solve the nonlinear vibration of the hard-coating cylindrical shell efficiently. The developed model may have great significance for vibration reduction of the cylindrical shell structures of the aero engine or aircraft. The influence of the strain dependence of the coating material on the complex stiffness matrix is considered in this model. Nonlinear iterative solution formulas with a unified iterative method are theoretically derived for solving the resonant frequency and response of the composite cylindrical shell. Then, a cylindrical shell coated with a thin layer of NiCoCrAlY + yttria-stabilized zirconia (YSZ) is chosen to demonstrate the proposed formulation, and the rationality is validated by comparing with the finite element iteration method (FEIM). Results show that the developed finite element method is more efficient, and the hard-coating cylindrical shell has the characteristics of soft nonlinearity due to the strain dependence of the coating material.
      PubDate: 2017-05-11
      DOI: 10.3390/coatings7050070
      Issue No: Vol. 7, No. 5 (2017)
       
  • Coatings, Vol. 7, Pages 71: Predicting the Wear of High Friction Surfacing
           Aggregate

    • Authors: David Woodward, Shaun Friel
      First page: 71
      Abstract: High friction surfacing (HFS) is a specialist type of road coating with very high skid resistance. It is used in the UK at locations where there is significant risk of serious or fatal accidents. This paper considers the aggregate used in HFS. Calcined bauxite is the only aggregate that provides the highest levels of skid resistance over the longest period. No naturally occurring aggregate has been found to give a comparable level of in-service performance. This paper reviews the historical development of HFS in the UK relating to aggregate. In-service performance is predicted in the laboratory using the Wear test which subjects test specimens to an estimated 5–8 years simulated trafficking. Examples are given of Wear test data. They illustrate why calcined bauxite performs better than natural aggregate. They show how the amount of calcined bauxite can be reduced by blending with high skid resistant natural aggregates. Data from the Wear test can be related to every HFS laboratory experiment and road trial carried out in the UK for over the last 50 years. Anyone considering the prediction of HFS performance needs to carefully consider the data given in this paper with any other test method currently being considered or used to investigate HFS.
      PubDate: 2017-05-16
      DOI: 10.3390/coatings7050071
      Issue No: Vol. 7, No. 5 (2017)
       
  • Coatings, Vol. 7, Pages 50: Studies on the Effect of Arc Current Mode and
           Substrate Rotation Configuration on the Structure and Corrosion Behavior
           of PVD TiN Coatings

    • Authors: Liam Ward, Antony Pilkington, Steve Dowey
      First page: 50
      Abstract: Thin, hard cathodic arc evaporated (CAE) metal nitride coatings are known to contain defects such as macro-particles, pinholes, voids and increased porosity, leading to reduced corrosion resistance. The focus of this research investigation was to compare the structure and corrosion behaviour of cathodic arc evaporated (CAE) TiN coatings deposited on AISI 1020 low carbon steel substrates using a pulsed current arc and a more conventional constant current arc source (DC). The effects of a double (2R) and triple (3R) substrate rotation configuration were also studied. Coating morphology and chemical composition were characterised using optical, SEM imaging and XRD analysis. Focus variation microscopy (FVM), an optical 3D measurement technique, was used to measure surface roughness. Corrosion studies were carried out using potentiodynamic scanning in 3.5% NaCl. Tafel extrapolation was carried out to determine Ecorr and Icorr values for the coated samples. In general, increased surface roughness, and to a certain extent, corrosion resistance, were associated with thicker coatings deposited using 2R, compared to 3R rotation configuration. The arc source mode (continuous or pulsed) was shown to have little effect on the corrosion behavior. Corrosion behavior was controlled by the presence of defects, pinholes and macro-particles at lower anodic potentials, while the formation of large pitted regions and aggressive corrosion of the underlying substrate was observed at higher anodic potentials.
      PubDate: 2017-04-04
      DOI: 10.3390/coatings7040050
      Issue No: Vol. 7, No. 4 (2017)
       
  • Coatings, Vol. 7, Pages 51: Effect on Concrete Surface Water Absorption
           upon Addition of Lactate Derived Agent

    • Authors: Renee Mors, Henk Jonkers
      First page: 51
      Abstract: Water tightness of a concrete cover layer is important, as it is typically used as a protective coating of the steel reinforcement. Water tightness can be impaired by crack formation or by permeability. A bacteria-based lactate-derived healing agent (HA) can be added to concrete to enhance the potential for restoration of water tightness. Bacterial conversion of the included carbon source results in CO2 production and subsequent CaCO3 precipitation, similar to the mechanism of concrete carbonation. Carbonation is known to densify concrete, particularly when using ordinary Portland cement (OPC), but to a much lower extend in slag-based concrete (CEM III/B). To identify the effect of HA addition on concrete properties, this study focusses on the ingress of moisture in non-cracked concrete surfaces by assessing capillary water absorption. Surface properties were determined for sealed and unsealed surfaces of concrete—either based on OPC or CEM III/B—before and after curing under three different conditions: Dry, wet, or humid. HA addition to concrete containing slag cement generated a surface less prone to continued drying, but resulted in higher water absorption. In contrast, surface water absorption significantly decreased upon HA addition to OPC-based samples, independent of the curing regime. It is therefore concluded that HA in its current form is suitable for application in OPC, but less in CEM III/B-based mixtures.
      PubDate: 2017-04-07
      DOI: 10.3390/coatings7040051
      Issue No: Vol. 7, No. 4 (2017)
       
  • Coatings, Vol. 7, Pages 52: The Effect of Temperature and Local pH on
           Calcareous Deposit Formation in Damaged Thermal Spray Aluminum (TSA)
           Coatings and Its Implication on Corrosion Mitigation of Offshore Steel
           Structures

    • Authors: Nataly Ce, Shiladitya Paul
      First page: 52
      Abstract: This paper is based on experimental data and provides better understanding of the mechanism of calcareous deposit formation on cathodically polarized steel surfaces exposed to synthetic seawater at 30 °C and 60 °C. The study comprises measurement of the interfacial pH of thermally sprayed aluminum (TSA) coated steel samples with and without a holiday (exposing 20% of the surface area). Tests were conducted at the corrosion potential for up to 350 h. It was experimentally determined that the local pH adjacent to the steel surface in the holiday region reached a maximum of 10.19 and 9.54 at 30 °C and 60 °C, respectively, before stabilizing at about 8.8 and 7.9 at the two temperatures. The interfacial pH on the TSA coating at 30 °C was initially 7.74 dropping to 4.76 in 220 h, while at 60 °C it increased from pH 6.41 to the range pH 7.0–8.5. The interfacial pH governed the deposition of brucite and aragonite from seawater on the steel surface cathodically polarized by the TSA. This mechanism is likely to affect the performance of TSA-coated offshore steel structures, especially when damaged in service.
      PubDate: 2017-04-11
      DOI: 10.3390/coatings7040052
      Issue No: Vol. 7, No. 4 (2017)
       
  • Coatings, Vol. 7, Pages 53: Preparation of Metal Coatings on Steel Balls
           Using Mechanical Coating Technique and Its Process Analysis

    • Authors: Liang Hao, Hiroyuki Yoshida, Takaomi Itoi, Yun Lu
      First page: 53
      Abstract: We successfully applied mechanical coating technique to prepare Ti coatings on the substrates of steel balls and stainless steel balls. The prepared samples were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The weight increase of the ball substrates and the average thickness of Ti coatings were also monitored. The results show that continuous Ti coatings were prepared at different revolution speeds after different durations. Higher revolution speed can accelerate the formation of continuous Ti coatings. Substrate hardness also markedly affected the formation of Ti coatings. Specifically, the substance with lower surface hardness was more suitable as the substrate on which to prepare Ti coatings. The substrate material plays a key role in the formation of Ti coatings. Specifically, Ti coatings formed more easily on metal/alloy balls than ceramic balls. The above conclusion can also be applied to other metal or alloy coatings on metal/alloy and ceramic substrates.
      PubDate: 2017-04-10
      DOI: 10.3390/coatings7040053
      Issue No: Vol. 7, No. 4 (2017)
       
  • Coatings, Vol. 7, Pages 54: Erosion Wear Investigation of HVOF Sprayed
           WC-10Co4Cr Coating on Slurry Pipeline Materials

    • Authors: Kaushal Kumar, Satish Kumar, Gurprit Singh, Jatinder Singh, Jashanpreet Singh
      First page: 54
      Abstract: In the present work, erosion wear due to slurry mixture flow has been investigated using a slurry erosion pot tester. Erosion tests are conducted on three different slurry pipe materials, namely, mild steel, SS202, and SS304, to establish the influence of rotational speed, concentration, and time period. In order to increase erosion wear resistance, a high-velocity oxy-fuel (HVOF) coating technique is used to deposit a WC-10Co4Cr coating on the surface of all piping materials. Experimental results show that rotational speed is a highly-influencing parameter for the erosion wear rate as compared to solid concentration, time duration, and weighted mean diameter. WC-10Co4Cr HVOF coating improved the erosion resistance of piping materials up to 3.5 times. From experimental data, the exponents of solid concentration, velocity, and the size of particles are calculated for the empirical erosion wear equation. A functional equation of the erosion wear rate is developed. The predicted erosion wear is in agreement with the experimental data and found to be within a deviation of ±12%.
      PubDate: 2017-04-12
      DOI: 10.3390/coatings7040054
      Issue No: Vol. 7, No. 4 (2017)
       
  • Coatings, Vol. 7, Pages 55: Application of High-Velocity Oxygen-Fuel
           (HVOF) Spraying to the Fabrication of Yb-Silicate Environmental Barrier
           Coatings

    • Authors: Emine Bakan, Georg Mauer, Yoo Sohn, Dietmar Koch, Robert Vaßen
      First page: 55
      Abstract: From the literature, it is known that due to their glass formation tendency, it is not possible to deposit fully-crystalline silicate coatings when the conventional atmospheric plasma spraying (APS) process is employed. In APS, rapid quenching of the sprayed material on the substrate facilitates the amorphous deposit formation, which shrinks when exposed to heat and forms pores and/or cracks. This paper explores the feasibility of using a high-velocity oxygen-fuel (HVOF) process for the cost-effective fabrication of dense, stoichiometric, and crystalline Yb2Si2O7 environmental barrier coatings. We report our findings on the HVOF process optimization and its resultant influence on the microstructure development and crystallinity of the Yb2Si2O7 coatings. The results reveal that partially crystalline, dense, and vertical crack-free EBCs can be produced by the HVOF technique. However, the furnace thermal cycling results revealed that the bonding of the Yb2Si2O7 layer to the Silicon bond coat needs to be improved.
      PubDate: 2017-04-18
      DOI: 10.3390/coatings7040055
      Issue No: Vol. 7, No. 4 (2017)
       
  • Coatings, Vol. 7, Pages 56: State of the Art of Antimicrobial Edible
           Coatings for Food Packaging Applications

    • Authors: Arantzazu Valdés, Marina Ramos, Ana Beltrán, Alfonso Jiménez, María Garrigós
      First page: 56
      Abstract: The interest for the development of new active packaging materials has rapidly increased in the last few years. Antimicrobial active packaging is a potential alternative to protect perishable products during their preparation, storage and distribution to increase their shelf-life by reducing bacterial and fungal growth. This review underlines the most recent trends in the use of new edible coatings enriched with antimicrobial agents to reduce the growth of different microorganisms, such as Gram-negative and Gram-positive bacteria, molds and yeasts. The application of edible biopolymers directly extracted from biomass (proteins, lipids and polysaccharides) or their combinations, by themselves or enriched with natural extracts, essential oils, bacteriocins, metals or enzyme systems, such as lactoperoxidase, have shown interesting properties to reduce the contamination and decomposition of perishable food products, mainly fish, meat, fruits and vegetables. These formulations can be also applied to food products to control gas exchange, moisture permeation and oxidation processes.
      PubDate: 2017-04-19
      DOI: 10.3390/coatings7040056
      Issue No: Vol. 7, No. 4 (2017)
       
 
 
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