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  Subjects -> ENGINEERING (Total: 2268 journals)
    - CHEMICAL ENGINEERING (190 journals)
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    - ELECTRICAL ENGINEERING (103 journals)
    - ENGINEERING (1201 journals)
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ENGINEERING (1201 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: 17)
AAPG Bulletin     Hybrid Journal   (Followers: 7)
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: 247)
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: 8)
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: 26)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
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: 22)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 26)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 29)
Advances in Operations Research     Open Access   (Followers: 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: 38)
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: 31)
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: 17)
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: 16)
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   (Followers: 1)
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)
Asia-Pacific Journal of Science and Technology     Open Access  
Asian Engineering Review     Open Access  
Asian Journal of Applied Science and Engineering     Open Access   (Followers: 1)
Asian Journal of Applied Sciences     Open Access   (Followers: 2)
Asian Journal of Biotechnology     Open Access   (Followers: 8)
Asian Journal of Control     Hybrid Journal  
Asian Journal of Current Engineering & Maths     Open Access  
Asian Journal of Technology Innovation     Hybrid Journal   (Followers: 8)
Assembly Automation     Hybrid Journal   (Followers: 2)
at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
ATZagenda     Hybrid Journal  
ATZextra worldwide     Hybrid Journal  
Australasian Physical & Engineering Sciences in Medicine     Hybrid Journal   (Followers: 1)
Australian Journal of Multi-Disciplinary Engineering     Full-text available via subscription   (Followers: 2)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 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: 5)
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: 32)
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   (Followers: 1)
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access   (Followers: 2)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 10)
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 14)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 10)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 25)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 43)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 8)
Case Studies in Thermal Engineering     Open Access   (Followers: 4)
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: 7)
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: 22)
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: 4)
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: 266)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 188)
Composites Part B : Engineering     Hybrid Journal   (Followers: 279)
Composites Science and Technology     Hybrid Journal   (Followers: 182)
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: 7)
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: 7)
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   (Followers: 1)
CTheory     Open Access  

        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 150: Effect of Particle Size on the Thermal Shock
           Resistance of Plasma-Sprayed YSZ Coatings

    • Authors: Jibo Huang, Weize Wang, Xiang Lu, Doudou Hu, Zhengqu Feng, Tianxu Guo
      First page: 150
      Abstract: In this study, yttria-stabilized zirconia (YSZ) coatings were deposited by atmospheric plasma spraying (APS) using feedstocks with two different particle sizes. The effect of particle size on the pore structure and failure mechanism of the coatings was investigated. The evolution of the pore structure of the two kinds of coatings during cyclic thermal shock test was described by quantitative metallography. The influence of pore orientation on the thermal stress of the coating system was analyzed by the finite element method. It was found that the coatings deposited using coarse particles show a high thermal shock life time. The orientation of the pores in the coatings prepared by different particle sizes was different. A structural parameter was proposed to effectively characterize the pore orientation of the coatings. Coatings prepared by coarse YSZ powder tend to form almost the same number of horizontal and vertical pores, while coatings prepared by fine powder tend to form horizontal ones parallel to the direction of the substrate. The simulation results revealed that the vertical pores can reduce the thermal stress in the coating. The results of this investigation are a benefit to the design and integrity of TBCs.
      Citation: Coatings
      PubDate: 2017-09-19
      DOI: 10.3390/coatings7090150
      Issue No: Vol. 7, No. 9 (2017)
       
  • Coatings, Vol. 7, Pages 151: Microstructure and Wear Behavior of
           FeCoCrNiMo0.2 High Entropy Coatings Prepared by Air Plasma Spray and the
           High Velocity Oxy-Fuel Spray Processes

    • Authors: Tianchen Li, Yong Liu, Bin Liu, Wenmin Guo, Liyou Xu
      First page: 151
      Abstract: In the present research, the spherical FeCoCrNiMo0.2 high entropy alloy (HEA) powders with a single FCC solid solution structure were prepared by gas atomization. Subsequently, the FeCoCrNiMo0.2 coatings with a different content of oxide inclusions were prepared by air plasma spraying (APS) and high-velocity oxy-fuel spraying (HVOF), respectively. The microstructure, phase composition, mechanical properties, and tribological behaviors of these HEA coatings were investigated. The results showed that both HEA coatings showed a typical lamellar structure with low porosity. Besides the primary FCC phase, a mixture of Fe2O3, Fe3O4, and AB2O4 (A = Fe, Co, Ni, and B = Fe, Cr) was identified as the oxide inclusions. The oxide content of the APS coating and HVOF coating was calculated to be 47.0% and 12.7%, respectively. The wear resistance of the APS coating was approximately one order of magnitude higher than that of the HVOF coating. It was mainly attributed to the self-lubricated effect caused by the oxide films. The mass loss of the APS coating was mainly ascribed to the breakaway of the oxide film, while the main wear mechanism of the HVOF coating was the abrasive wear.
      Citation: Coatings
      PubDate: 2017-09-20
      DOI: 10.3390/coatings7090151
      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 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 178: Evolution of Nanostructure and Metastable
           Phases at the Surface of a HCPEB-Treated WC-6% Co Hard Alloy with
           Increasing Irradiation Pulse Numbers

    • Authors: Yue Zhang, Fuyang Yu, Shengzhi Hao, Fuyu Dong, Yang Xu, Wubin Geng, Nannan Zhang, Nathalie Gey, Thierry Grosdidier, Chuang Dong
      First page: 178
      Abstract: This work investigates the mechanisms of the microstructure evolution in the melted surface layers of a WC-6% Co hard alloy when increasing the number of pulses of irradiation by high-current pulsed electron beam (HCPEB) treatment. After one pulse of irradiation, about 50% of the stable hcp WC phase was melted and resolidified into the metastable fcc form (WC1−x). When increasing the numbers of pulse irradiation, the WC phase decomposed into ultrafine-grained WC1−x plus nanosized graphite under our selected energy condition. Because of the rapidity of HCPEB carried under vacuum, the formation of the brittle W2C phase was avoided. In the initial Co-rich areas, where the Co was evaporated, melting and solidification led to the formation of nanostructures Co3W9C4 and Co3W3C. The volume fraction of the nano domains containing WC1−x, Co3W9C4, and Co3W3C phases reached its maximum after 20 pulses of irradiation. The improved properties after 20 pulses are therefore due to the presence of nano graphite that served as lubricant and dramatically decreased the friction coefficient, while the ultrafine-grained carbides and the nano domains contribute to the improvement of the surface microhardness and wear resistance.
      Citation: Coatings
      PubDate: 2017-10-26
      DOI: 10.3390/coatings7110178
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 179: Aluminum Templates of Different Sizes with
           Micro-, Nano- and Micro/Nano-Structures for Cell Culture

    • Authors: Ming-Liang Yen, Hao-Ming Hsiao, Chiung-Fang Huang, Yi Lin, Yung-Kang Shen, Yu-Liang Tsai, Chun-Wei Chang, Hsiu-Ju Yen, Yi-Jung Lu, Yun-Wen Kuo
      First page: 179
      Abstract: This study investigates the results of cell cultures on aluminum (Al) templates with flat-structures, micro-structures, nano-structures and micro/nano-structures. An Al template with flat-structure was obtained by electrolytic polishing; an Al template with micro-structure was obtained by micro-powder blasting; an Al template with nano-structure was obtained by aluminum anodization; and an Al template with micro/nano-structure was obtained by micro-powder blasting and then anodization. Osteoblast-like cells were cultured on aluminum templates with various structures. The microculture tetrazolium test assay was utilized to assess the adhesion, elongation, and proliferation behaviors of cultured osteoblast-like cells on aluminum templates with flat-structures, micro-structures, nano-structures, and micro/nano-structures. The results showed that the surface characterization of micro/nano-structure of aluminum templates had superhydrophilic property, and these also revealed that an aluminum template with micro/nano-structure could provide the most suitable growth situation for cell culture.
      Citation: Coatings
      PubDate: 2017-10-26
      DOI: 10.3390/coatings7110179
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 180: Evaluation of Accelerated Ageing Tests for
           Metallic and Non-Metallic Graffiti Paints Applied to Stone

    • Authors: Patricia Sanmartín, Francesca Cappitelli
      First page: 180
      Abstract: Graffiti are increasingly observed on urban and peri-urban buildings and their removal requires a huge financial outlay by local governments and agencies. Graffiti are not usually removed immediately, but rather over the passage of time, viz. months or even years. In this study, which forms part of a wider research project on graffiti removal, different methods (gravimetric analysis, examination of digital images, colour and infrared measurements) were used to evaluate the performance of accelerated ageing tests (involving exposure to humidity, freeze-thawing cycles and NaCl and Na2SO4 salts) for graffiti painted on stone. Silver (metallic) and black (non-metallic) graffiti spray paints were applied to two types of igneous rock (granite and rhyolitic ignimbrite) and one sedimentary rock (fossiliferous limestone, i.e., biocalcarenite). The metallic and non-metallic graffiti spray paints acted differently on the stone surfaces, both chemically and physically. Older graffiti were found to be more vulnerable to weathering agents. The ageing test with NaCl and particularly Na2SO4, both applied to granite, proved the most severe on the paints, yielding more detrimental and faster artificial ageing of the type of material under study.
      Citation: Coatings
      PubDate: 2017-10-30
      DOI: 10.3390/coatings7110180
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 181: Inhibitory Properties of Neomycin Thin Film
           Formed on Carbon Steel in Sulfuric Acid Solution: Electrochemical and AFM
           Investigation

    • Authors: Adriana Samide, Gabriela Iacobescu, Bogdan Tutunaru, Roxana Grecu, Cristian Tigae, Cezar Spînu
      First page: 181
      Abstract: Our study aims to implement a strategy to reduce the carbon steel corrosion rate in a sulfuric acid solution, using an expired drug with adsorption affinity on the metal surface. To investigate the corrosion protection efficiency of an environmental friendly inhibitor, namely neomycin sulfate (NMS), the electrochemical measurements were applied on carbon steel immersed in 1.0 M H2SO4 solution with and without NMS. The protective layer that formed on the steel surface was studied by atomic force microscopy (AFM). The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) showed that the presence of the neomycin sulfate in acid solution leads to the decrease in corrosion current density (icorr) and the increase of polarization resistance (Rp). The mixed mechanism between physical and chemical adsorption of NMS molecules on the steel surface was proposed according to the Langmuir adsorption isotherm. AFM indicated that the NMS molecules contributed to a protective layer formation by their adsorption on the steel surface. The AFM parameters, such as root mean square roughness (Rq), average roughness (Ra), and maximum peak to valley height (Rp−v) revealed that in the presence of NMS a smoother surface of carbon steel was obtained, compared to the steel surface corroded in sulfuric acid blank solution.
      Citation: Coatings
      PubDate: 2017-10-31
      DOI: 10.3390/coatings7110181
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 182: Microwave-Assisted Dip Coating of Aloe Vera
           on Metallocene Polyethylene Incorporated with Nano-Rods of Hydroxyapaptite
           for Bone Tissue Engineering

    • Authors: Hairong Wang, Xueliang Zhang, Mohan Mani, Saravana Jaganathan, Yi Huang, Chengzheng Wang
      First page: 182
      Abstract: Bone tissue engineering widely explores the use of ceramic reinforced polymer-matrix composites. Among the various widely-used ceramic reinforcements, hydroxyapatite is an undisputed choice due to its inherent osteoconductive nature. In this study, a novel nanocomposite comprising metallocene polyethylene (mPE) incorporated with nano-hydroxyapaptite nanorods (mPE-nHA) was synthesized and dip coated with Aloe vera after subjecting it to microwave treatment. The samples were characterized using contact angle, Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), atomic force microscopy (AFM) and 3D Hirox microscopy scanning. Contact angle results show that the hydrophilicity of mPE-nHA improved notably with the coating of Aloe vera. The surface topology and increase in surface roughness were observed using the SEM, AFM and 3D Hirox microscopy. Blood compatibility assays of pure mPE and the Aloe vera coated nanocomposite were performed. The prothrombin time (PT) was delayed by 1.06% for 24 h Aloe-vera-treated mPE-nHA compared to the pristine mPE-nHA. Similarly, the 24 h Aloe-vera-coated mPE-nHA nanocomposite prolonged the activated partial thromboplastin time (APTT) by 41 s against the control of pristine mPE-nHA. The hemolysis percentage was also found to be the least for the 24 h Aloe-vera-treated mPE-nHA which was only 0.2449% compared to the pristine mPE-nHA, which was 2.188%. To conclude, this novel hydroxyapatite-reinforced, Aloe-vera-coated mPE with a better mechanical and anti-thrombogenic nature may hold a great potential to be exploited for bone tissue engineering applications.
      Citation: Coatings
      PubDate: 2017-10-31
      DOI: 10.3390/coatings7110182
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 183: Characterization of Barnyard Millet Starch
           Films Containing Borage Seed Oil

    • Authors: Thi Cao, So-Young Yang, Kyung Song
      First page: 183
      Abstract: In this study, barnyard millet starch (BMS) was used to prepare edible films. Antioxidant activity was conferred to the BMS film by incorporating borage seed oil (BO). The physical, optical, and thermal properties as well as antioxidant activities of the films were evaluated. The incorporation of BO into the BMS films decreased the tensile strength from 9.46 to 4.69 MPa and increased the elongation at break of the films from 82.49% to 103.87%. Water vapor permeability, water solubility, and moisture content of the BMS films decreased with increasing BO concentration, whereas Hunter b value and opacity increased, L and a values of the films decreased. The BMS films containing BO exhibited antioxidant activity that increased proportionally with increased BO concentration. In particular, the BMS film with 1.0% BO exhibited the highest antioxidant activity and light barrier properties among the BMS films. Therefore, the BMS films with added BO can be used as an antioxidant packaging material.
      Citation: Coatings
      PubDate: 2017-11-01
      DOI: 10.3390/coatings7110183
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 184: Biodegradable Ceramics Consisting of
           Hydroxyapatite for Orthopaedic Implants

    • Authors: Thomas Monsees, Funda Ak Azem, Cosmin Cotrut, Mariana Braic, Radwan Abdulgader, Iulian Pana, Isil Birlik, Adrian Kiss, Robin Booysen, Alina Vladescu
      First page: 184
      Abstract: This study aims to analyze hydroxyapatite (HAP) coatings enriched with Mg and Ti prepared by a magnetron sputtering technique on Ti6Al4V substrate. For preparation of the coatings, three magnetron targets (HAP, MgO and TiO2) were simultaneously co-worked. The concentration of Mg added was varied by modifying the power applied to the MgO target. In all coatings, the Ti concentration was maintained constant by keeping the same cathode power fed during the whole deposition. The influence of different Mg dopant contents on the formation of phase, microstructure and morphology of the obtained Ti-doped HAP coatings were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Moreover, the effects of Mg addition upon corrosion, mechanical and biological properties were also investigated. Mg- and Ti-doped HAP coating obtained at low radio-frequency (RF) power fed to the MgO target provided material with high corrosion resistance compared to other coatings and bare alloy. A slight decrease in hardness of the coatings was found after the Mg addition, from 8.8 to 5.7 GPa. Also, the values of elastic modulus were decreased from 87 to 53 GPa, this being an advantage for biomedical applications. The coatings with low Mg concentration proved to have good deformation to yielding and higher plastic properties. Biological test results showed that the novel surfaces exhibited excellent properties for the adhesion and growth of bone cells. Moreover, early adherent vital cell numbers were significantly higher on both coatings compared to Ti6Al4V, suggesting that Mg ions may accelerate initial osteoblast adhesion and proliferation.
      Citation: Coatings
      PubDate: 2017-11-03
      DOI: 10.3390/coatings7110184
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 185: Surface Texturing of CVD Diamond Assisted by
           Ultrashort Laser Pulses

    • Authors: Daniele Trucchi, Alessandro Bellucci, Marco Girolami, Matteo Mastellone, Stefano Orlando
      First page: 185
      Abstract: Diamond is a wide bandgap semiconductor with excellent physical properties which allow it to operate under extreme conditions. However, the technological use of diamond was mostly conceived for the fabrication of ultraviolet, ionizing radiation and nuclear detectors, of electron emitters, and of power electronic devices. The use of nanosecond pulse excimer lasers enabled the microstructuring of diamond surfaces, and refined techniques such as controlled ablation through graphitization and etching by two-photon surface excitation are being exploited for the nanostructuring of diamond. On the other hand, ultrashort pulse lasers paved the way for a more accurate diamond microstructuring, due to reduced thermal effects, as well as an effective surface nanostructuring, based on the formation of periodic structures at the nanoscale. It resulted in drastic modifications of the optical and electronic properties of diamond, of which “black diamond” films are an example for future high-temperature solar cells as well as for advanced optoelectronic platforms. Although experiments on diamond nanostructuring started almost 20 years ago, real applications are only today under implementation.
      Citation: Coatings
      PubDate: 2017-11-03
      DOI: 10.3390/coatings7110185
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 186: Study on the Formation of Reaction Phase to
           Si Addition in Boron Steel Hot-Dipped in Al–7Ni Alloy

    • Authors: Jung-Gil Yun, Jae-Hyeong Lee, Sung-Yun Kwak, Chung-Yun Kang
      First page: 186
      Abstract: In order to reduce the intermetallic compounds formed during the application of an Al–7Ni wt % hot-dip multifunctional coating on boron steel, developed for Tailor Welded Blanks (TWB) and hot stamping, 2–6 wt % Si was added to the coating to change the reaction layer. The coating was run at 690 °C for 120 s. Al9FeNi phases were formed on the steel interface, Fe2Al5 was formed on the steel, FeAl3 was generated between the existing layers, and flake-type Al2Fe3Si3 was formed in the Fe2Al5 phase, depending on the Si content. In addition, as Si was added to the coating, the thickness of the Fe2Al5 phase decreased and the thickness of the Al9FeNi phase and Al2Fe3Si3 increased. The decrease in the thickness of the Fe2Al5 phase was mainly due to the effect of the Si solid solution and the Al2Fe3Si3 formation in the Fe2Al5 phase. The reason for the growth of Al9FeNi is that the higher the Si content in the coating, the more the erosion of the interface of the steel material due to the coating solution. Therefore, the outflow of Fe into the coating liquid increased.
      Citation: Coatings
      PubDate: 2017-11-04
      DOI: 10.3390/coatings7110186
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 187: Tribological and Wear Performance of Carbide
           Tools with TiB2 PVD Coating under Varying Machining Conditions of TiAl6V4
           Aerospace Alloy

    • Authors: Jose Mario Paiva, Mohamed Abdul Monim Shalaby, Mohammad Chowdhury, Lev Shuster, Stanislav Chertovskih, Danielle Covelli, Edinei Locks Junior, Pietro Stolf, Amr Elfizy, Carlos Alberto Schuch Bork, German Fox-Rabinovich, Stephen Clarence Veldhuis
      First page: 187
      Abstract: Tribological phenomena and tool wear mechanisms during machining of hard-to-cut TiAl6V4 aerospace alloy have been investigated in detail. Since cutting tool wear is directly affected by tribological phenomena occurring between the surfaces of the workpiece and the cutting tool, the performance of the cutting tool is strongly associated with the conditions of the machining process. The present work shows the effect of different machining conditions on the tribological and wear performance of TiB2-coated cutting tools compared to uncoated carbide tools. FEM modeling of the temperature profile on the friction surface was performed for wet machining conditions under varying cutting parameters. Comprehensive characterization of the TiB2 coated vs. uncoated cutting tool wear performance was made using optical 3D imaging, SEM/EDX and XPS methods respectively. The results obtained were linked to the FEM modeling. The studies carried out show that during machining of the TiAl6V4 alloy, the efficiency of the TiB2 coating application for carbide cutting tools strongly depends on cutting conditions. The TiB2 coating is very efficient under roughing at low speeds (with strong buildup edge formation). In contrast, it shows similar wear performance to the uncoated tool under finishing operations at higher cutting speeds when cratering wear predominates.
      Citation: Coatings
      PubDate: 2017-11-04
      DOI: 10.3390/coatings7110187
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 188: Determining the Presence of Spalted Wood in
           Spanish Marquetry Woodworks of the 1500s through the 1800s

    • Authors: Patricia Vega Gutierrez, Seri Robinson
      First page: 188
      Abstract: The process of using fungal-colored wood (spalted wood) for marquetry and intarsia woodworks in Italy and Germany was very popular from the 1400–1600s, with some instances continuing as late as the 1800s. While spalted marquetry in these countries is relatively well documented, less is known about its use in other parts of Europe. One of the primary reasons for this lack of knowledge is the difficulty in identifying spalted wood, especially the blue-green variety produced from Chlorociboria species, from wood dyed with copper-based compounds or other synthetics. The most reliable testing method involves destructive sampling, where a small piece is taken from the work, the pigment extracted, and an analysis performed. Such sampling is simply not feasible, nor often allowed, on ancient artwork. To make a reliable, non-destructive identification of spalted wood, a visual method based on anatomical characteristics of spalted wood was developed to differentiate spalted wood from dyed wood. High-resolution pictures were taken from wooden artifacts containing blue-green colored wood in collections at the National Museum of Decorative Arts (MNAD), the Royal Site Monastery El Escorial and the Bilbao Museum of Fine Arts in Spain. The concentration of pigment in the rays, the color distribution, the size of the piece and the date of production, were analyzed. With the use of this new visual method, it was possible to determine that intarsia artifacts, held in Spain but of Augsburg origin from the 1500–1600s, contained spalted wood details. Meanwhile, Spanish and Italian intarsia artifacts from the 1800s were found to only contain dyed wood.
      Citation: Coatings
      PubDate: 2017-11-04
      DOI: 10.3390/coatings7110188
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 189: Ta–Zr–N Thin Films Fabricated through
           HIPIMS/RFMS Co-Sputtering

    • Authors: Li-Chun Chang, Ching-Yen Chang, Ya-Wen You
      First page: 189
      Abstract: Ta–Zr–N thin films were fabricated through co-deposition of radio-frequency magnetron sputtering and high-power impulse magnetron sputtering (HIPIMS/RFMS co-sputtering). The oxidation resistance of the fabricated films was evaluated by annealing the samples in a 15-ppm O2-N2 atmosphere at 600 °C for 4 and 8 h. The mechanical properties and surface roughness of the as-deposited and annealed thin films were evaluated. The results indicated that the HIPIMS/RFMS co-sputtered Ta–Zr–N thin films exhibited superior mechanical properties and lower surface roughness than did the conventional direct current-sputtered Ta–Zr–N thin films and HIPIMS-fabricated ZrNx thin films in both the as-deposited and annealed states.
      Citation: Coatings
      PubDate: 2017-11-04
      DOI: 10.3390/coatings7110189
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 190: Role of Phase Composition of PEO Coatings on
           AA2024 for In-Situ LDH Growth

    • Authors: Maria Serdechnova, Marta Mohedano, Anissa Bouali, Daniel Höche, Boris Kuznetsov, Sergey Karpushenkov, Carsten Blawert, Mikhail Zheludkevich
      First page: 190
      Abstract: Plasma electrolytic oxidation (PEO) is an environmentally friendly anodizing technique leading to the formation of a ceramic-like coatings under high-voltage discharges. Layered double hydroxides (LDHs) were grown directly on γ, α, and amorphous Al2O3 powders, respectively, in order to investigate the phase responsible for in-situ LDH growth on PEO coating. Furthermore, it is shown that LDH growth is limited by the high tortuosity of the PEO layer and the accessibility of Al ( OH ) 4 − anions from the substrate covered with thin amorphous aluminum oxide, through the pores.
      Citation: Coatings
      PubDate: 2017-11-06
      DOI: 10.3390/coatings7110190
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 191: Friction and Wear Behavior of an Ag–Mo
           Co-Implanted GH4169 Alloy via Ion-Beam-Assisted Bombardment

    • Authors: Jiajun Zhu, Meng Xu, Wulin Yang, Deyi Li, Lingping Zhou, Licai Fu
      First page: 191
      Abstract: Ag, Mo, and Ag–Mo were respectively implanted into GH4169 alloy substrates without heating via ion-beam-assisted bombardment technology (IBAB). In addition, the wear performance under low sliding speed and applied load were researched at room temperature (RT). A small amount silver molybdate phase could be detected on the surface of the co-implanted GH4169 alloy bombarded by a high-energy ion beam. The average friction coefficients under the steady wear state had almost no change at all. Compared with the un-implanted GH4169 alloys, the wear rate of the GH4169 alloys with co-implantation of Ag and Mo was reduced by 75%. A large amount of the silver molybdate phase could be generated due to the tribo-reaction on the worn surface during sliding. It benefits the formation of continuous oxide layers as lubrication and protected layers, leading to the change in the predominant wear mechanism from abrasion and adhesion wear to oxidation wear.
      Citation: Coatings
      PubDate: 2017-11-06
      DOI: 10.3390/coatings7110191
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 192: Visible-Light-Driven, Dye-Sensitized TiO2
           Photo-Catalyst for Self-Cleaning Cotton Fabrics

    • Authors: Ishaq Ahmad, Chi-wai Kan
      First page: 192
      Abstract: We report here the photo-catalytic properties of dye-sensitized TiO2-coated cotton fabrics. In this study, visible-light-driven, self-cleaning cotton fabrics were developed by coating the cotton fabrics with dye-sensitized TiO2. TiO2 nano-sol was prepared via the sol-gel method and the cotton fabric was coated with this nano-sol by the dip-pad–dry-cure method. In order to enhance the photo-catalytic properties of this TiO2-coated cotton fabric under visible light irradiation, the TiO2-coated cotton fabric was dyed with a phthalocyanine-based reactive dye, C.I. Reactive Blue 25 (RB-25), as a dye sensitizer for TiO2. The photo-catalytic self-cleaning efficiency of the resulting dye/TiO2-coated cotton fabrics was evaluated by degradation of Rhodamine B (RhB) and color co-ordinate measurements. Dye/TiO2-coated cotton fabrics show very good photo-catalytic properties under visible light.
      Citation: Coatings
      PubDate: 2017-11-06
      DOI: 10.3390/coatings7110192
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 193: In Situ Synthesis and Electrophoretic
           Deposition of NiO/Ni Core-Shell Nanoparticles and Its Application as
           Pseudocapacitor

    • Authors: Joaquin Yus, Begoña Ferrari, Antonio Sanchez-Herencia, Alvaro Caballero, Julian Morales, Zoilo Gonzalez
      First page: 193
      Abstract: A simple, low cost and transferable colloidal processing method and the subsequent heat treatment has been optimized to prepare binder-free electrodes for their application in supercapacitors. NiO/Ni core–shell hybrid nanostructures have been synthetized by heterogeneous precipitation of metallic Ni nanospheres onto NiO nanoplatelets as seed surfaces. The electrophoretic deposition (EPD) has been used to shape the electroactive material onto 3D substrates such as Ni foams. The method has allowed us to control the growth and the homogeneity of the NiO/Ni coatings. The presence of metallic Nickel in the microstructure and the optimization of the thermal treatment have brought several improvements in the electrochemical response due to the connectivity of the final microstructure. The highest specific capacitance value has been obtained using a thermal treatment of 325 °C during 1 h in Argon. At this temperature, necks formed among ceramic-metallic nanoparticles preserve the structural integrity of the microstructure avoiding the employment of binders to enhance their connectivity. Thus, a compromise between porosity and connectivity should be established to improve electrochemical performance.
      Citation: Coatings
      PubDate: 2017-11-08
      DOI: 10.3390/coatings7110193
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 194: Fabrication of an Anisotropic
           Superhydrophobic Polymer Surface Using Compression Molding and Dip Coating
           

    • Authors: Kyong-Min Lee, Chi-Vinh Ngo, Ji-Young Jeong, Eun-chae Jeon, Tae-Jin Je, Doo-Man Chun
      First page: 194
      Abstract: Many studies of anisotropic wetting surfaces with directional structures inspired from rice leaves, bamboo leaves, and butterfly wings have been carried out because of their unique liquid shape control and transportation. In this study, a precision mechanical cutting process, ultra-precision machining using a single crystal diamond tool, was used to fabricate a mold with microscale directional patterns of triangular cross-sectional shape for good moldability, and the patterns were duplicated on a flat thermoplastic polymer plate by compression molding for the mass production of an anisotropic wetting polymer surface. Anisotropic wetting was observed only with microscale patterns, but the sliding of water could not be achieved because of the pinning effect of the micro-structure. Therefore, an additional dip coating process with 1H, 1H, 2H, 2H-perfluorodecythricholosilanes, and TiO2 nanoparticles was applied for a small sliding angle with nanoscale patterns and a low surface energy. The anisotropic superhydrophobic surface was fabricated and the surface morphology and anisotropic wetting behaviors were investigated. The suggested fabrication method can be used to mass produce an anisotropic superhydrophobic polymer surface, demonstrating the feasibility of liquid shape control and transportation.
      Citation: Coatings
      PubDate: 2017-11-10
      DOI: 10.3390/coatings7110194
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 195: Nucleation and Growth of Intermetallic
           Compounds Formed in Boron Steel Hot-Dipped in Al–Ni alloy

    • Authors: Jae-Hyeong Lee, Jung-Gil Yun, Sung-Yun Kwak, Chung-Yun Kang
      First page: 195
      Abstract: The formation mechanism of intermetallic compounds formed in boron steel hot-dipped in Al–7Ni (wt %) at 690 °С for 10–120 s was studied by identifying the intermetallic phases and investigating the growth process. Initially, a Fe3O4 oxide layer formed on the steel. The oxide layer separated into multiple layers sporadically; following this, the Al–Ni molten alloy permeated into the region of the oxide layer breakdown and formed the Al9FeNi (T, monoclinic, space group: P21/c) phase on the steel surfaces. The Al9FeNi (T) phase formed from the reaction between the Al–Ni molten alloy and Fe eluted from the steel; this phase not only acts as an Al interdiffusion channel, but also as a barrier for Fe; and facilitates only grain growth without a significant change in thickness. Inside the steel, the Fe2Al5 (η, orthorhombic, space group: Cmcm) phase grows along the c-axis in the [001] direction; and has a long columnar structure. The Fe3AlC (κ, Cubic, space group: Pm3m) phase is formed owing to a reduction in the Al concentration and the simultaneous diffusion and discharge of C toward the steel interface, as C cannot dissolve in the Fe2Al5 (η) phase.
      Citation: Coatings
      PubDate: 2017-11-10
      DOI: 10.3390/coatings7110195
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 196: Effective Postharvest Preservation of
           Kiwifruit and Romaine Lettuce with a Chitosan Hydrochloride Coating

    • Authors: Elena Fortunati, Geremia Giovanale, Francesca Luzi, Angelo Mazzaglia, Josè Kenny, Luigi Torre, Giorgio Balestra
      First page: 196
      Abstract: Kiwifruits and romaine lettuce, among the most horticulturally-consumed fresh products, were selected to investigate how to reduce damage and losses before commercialization. The film-forming properties, physico-chemical, and morphological characteristics, as well as the antimicrobial response against Botrytis cinerea and Pectobacterium carotovorum subsp. carotovorum of chitosan hydrochloride (CH)-based coatings were investigated. The results underlined the film-forming capability of this CH that maintained its physico-chemical characteristics also after dissolution in water. Morphological investigations by FESEM (Field Emission Scanning Electron Microscopy) underlined a well-distributed and homogeneous thin coating (less than 3–5 μm) on the lettuce leaves that do not negatively affect the food product functionality, guaranteeing the normal breathing of the food. FESEM images also highlighted the good distribution of CH coating on kiwifruit peels. The in vitro antimicrobial assays showed that both the mycelial growth of Botrytis cinerea and the bacterial growth of Pectobacterium carotovorum subsp. carotovorum were totally inhibited by the presence of CH, whereas in vivo antimicrobial properties were proved for 5–7 days on lettuce and until to 20–25 days on kiwifruits, demonstrating that the proposed coating is able to contrast gray mold frequently caused by the two selected plant pathogens during postharvest phases of fruit or vegetable products.
      Citation: Coatings
      PubDate: 2017-11-11
      DOI: 10.3390/coatings7110196
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 197: Characterization of Hydroxyapatite (HA)
           Sputtering Targets by APS Methods

    • Authors: Kuo-Yung Hung, Hong-Chen Lai, Yung-Chin Yang, Hui-Ping Feng
      First page: 197
      Abstract: Radio frequency (RF) sputtering is a potential medical device coating technology that is commercializable; however, a suitable commercialized target for sputtering the hydroxyapatite (HA) coating onto titanium medical devices is more important. Therefore, this study used three HA targets in conducting sputtering experiments for HA films, which were manufactured in a laboratory by using three different processes: cold pressing and sintering (CPS), hot isostatic pressing (HIP), and atmospheric plasma spraying (APS). Subsequently, the sputtering performance of each type of target and the properties of the HA films were assessed to develop an appropriate process for modifying the surfaces of medical devices. The experimental results showed that the APS target, with a density of approximately 2.83 g/cm3, was suitable for use in HA sputtering. Additionally, the APS target could withstand a high discharge power over 300 W, whereas the CPS target could nearly endure a power below 70 W. The APS target, with Ca/P ratio of 2.401, consisted of a combination of HA, α-tricalcium phosphate (α-TCP), β-TCP, and tetracalcium phosphate phases (TTCP). In addition to being able to perform at a high sputtering power of more than 300 W, the APS target achieved a higher deposition rate than did the CPS target. This study shows that the processing technology used for the APS target is a potential method for applying HA sputtering for the surface modification of artificial aggregates.
      Citation: Coatings
      PubDate: 2017-11-11
      DOI: 10.3390/coatings7110197
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 198: Effect of Microstructure on the Thermal
           Conductivity of Plasma Sprayed Y2O3 Stabilized Zirconia (8% YSZ)

    • Authors: Ningning Hu, Matiullah Khan, Yongzhe Wang, Xuemei Song, Chucheng Lin, Chengkang Chang, Yi Zeng
      First page: 198
      Abstract: In this paper, the effect of microstructure on the thermal conductivity of plasma-sprayed Y2O3 stabilized ZrO2 (YSZ) thermal barrier coatings (TBCs) is investigated. Nine freestanding samples deposited on aluminum alloys are studied. Cross-section morphology such as pores, cracks, m-phase content, grain boundary density of the coated samples are examined by scanning electron microscopy (SEM) and electron back-scattered diffraction (EBSD). Multiple linear regressions are used to develop quantitative models that describe the relationship between the particle parameters, m-phase content and features of the microstructure such as porosity, crack-porosity, and the length density of small and big angle-cracks. Moreover, the relationship between the microstructure and thermal conductivity is investigated. Results reveal that the thermal conductivity of the coating is mainly determined by the microstructure and grain boundary density at room temperature (25 °C), and by the length density of big-angle-crack, monoclinic phase content and grain boundary density at high temperature (1200 °C).
      Citation: Coatings
      PubDate: 2017-11-13
      DOI: 10.3390/coatings7110198
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 199: Electrophoretic Deposition as a New Bioactive
           Glass Coating Process for Orthodontic Stainless Steel

    • Authors: Kyotaro Kawaguchi, Masahiro Iijima, Kazuhiko Endo, Itaru Mizoguchi
      First page: 199
      Abstract: This study investigated the surface modification of orthodontic stainless steel using electrophoretic deposition (EPD) of bioactive glass (BG). The BG coatings were characterized by spectrophotometry, scanning electron microscopy with energy dispersive X-ray spectrometry, and X-ray diffraction. The frictional properties were investigated using a progressive load scratch test. The remineralization ability of the etched dental enamel was studied according to the time-dependent mechanical properties of the enamel using a nano-indentation test. The EPD process using alternating current produced higher values in both reflectance and lightness. Additionally, the BG coating was thinner than that prepared using direct current, and was completely amorphous. All of the BG coatings displayed good interfacial adhesion, and Si and O were the major components. Most BG-coated specimens produced slightly higher frictional forces compared with non-coated specimens. The hardness and elastic modulus of etched enamel specimens immersed with most BG-coated specimens recovered significantly with increasing immersion time compared with the non-coated specimen, and significant acid-neutralization was observed for the BG-coated specimens. The surface modification technique using EPD and BG coating on orthodontic stainless steel may assist the development of new non-cytotoxic orthodontic metallic appliances having satisfactory appearance and remineralization ability.
      Citation: Coatings
      PubDate: 2017-11-13
      DOI: 10.3390/coatings7110199
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 200: Effect of Initial Surface Roughness on
           Cavitation Erosion Resistance of Arc-Sprayed Fe-Based
           Amorphous/Nanocrystalline Coatings

    • Authors: Jinran Lin, Zehua Wang, Jiangbo Cheng, Min Kang, Xiuqing Fu, Sheng Hong
      First page: 200
      Abstract: The arc spraying process was used to prepare Fe-based amorphous/nanocrystalline coating. The cavitation erosion behaviors of FeNiCrBSiNbW coatings with different surface roughness levels were investigated in distilled water. The results showed that FeNiCrBSiNbW coating adhered well to the substrate, and was compact with porosity of less than 2%. With increasing initial surface roughness, the coatings showed an increase in mass loss of cavitation erosion damage. The amount of pre-existing defects on the initial surface of the coatings was found to be a significant factor for the difference in the cavitation erosion behavior. The cavitation erosion damage for the coatings was a brittle erosion mode. The evolution of the cavitation erosion mechanism of the coatings with the increase of the initial surface roughness was micro-cracks, pits, detachment of fragments, craters, cracks, pullout of the un-melted particle, and massive exfoliations.
      Citation: Coatings
      PubDate: 2017-11-14
      DOI: 10.3390/coatings7110200
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 201: Mechanical and Spectroscopic Analysis of
           Retrieved/Failed Dental Implants

    • Authors: Umer Daood, Ninette Banday, Zohaib Akram, James Tsoi, Prasanaa Neelakantan, Hanan Omar, Tariq Abduljabbar, Fahim Vohra, Nawwaf Al-Hamoudi, Amr Fawzy
      First page: 201
      Abstract: The purpose of this study was to examine surface alterations and bone formation on the surface of failed dental implants (Straumann [ST] and TiUnite [TiUn]) removed due to any biological reason. In addition, failure analysis was performed to test mechanical properties. Dental implants (n = 38) from two manufacturers were collected and subjected to chemical cleaning. The presence of newly formed hydroxyapatite bone around failed implants was evaluated using micro-Raman spectroscopy. Scanning electron microscopy was used to identify surface defects. Mechanical testing was performed using a Minneapolis servo-hydraulic system (MTS) along with indentation using a universal testing machine and average values were recorded. A statistical analysis of mechanical properties was done using an unpaired t test, and correlation between observed defects was evaluated using Chi-square (p = 0.05). Apatite-formation was evident in both implants, but was found qualitatively more in the ST group. No significant difference was found in indentation between the two groups (p > 0.05). The percentage of “no defects” was significantly lower in the ST group (71%). Crack-like and full-crack defects were observed in 49% and 39% of TiUn. The ST group showed 11,061 cycles to failure as compared with 10,021 cycles in the TiUnite group. Implant failure mechanisms are complex with a combination of mechanical and biological reasons and these factors are variable with different implant systems.
      Citation: Coatings
      PubDate: 2017-11-15
      DOI: 10.3390/coatings7110201
      Issue No: Vol. 7, No. 11 (2017)
       
  • Coatings, Vol. 7, Pages 152: Wood-Rotting Fungal Pigments as Colorant
           Coatings on Oil-Based Textile Dyes

    • Authors: Mardonio Palomino Agurto, Sarath Vega Gutierrez, Hsiou-Lien Chen, Seri Robinson
      First page: 152
      Abstract: Opportunities for alternatives to synthetic textile dyes are of increasing importance as the world looks to minimize its ecological footprint. Fungal pigments within a unique class of wood-rotting (“spalting”) fungi have been under investigation for several years as a possible solution, and have been shown to be ideally suited as textile dye coatings. Unfortunately, the solvent currently in use for these colorants is dichloromethane (DCM), which is an environmental problem as well as a potential human carcinogen. Recently, researchers found that the pigments from Chlorociboria species, Scytalidium cuboideum, and Scytalidium ganodermophthorum could be carried in some natural oils, which opened up a potential method of delivering pigments onto a host of substrates without utilizing DCM. Although the pigments can be carried in oil, no testing has thus far been conducted as to how oil affects the binding properties of the pigments onto textiles, or how the oil might affect the pigments directly. In this paper, the pigments produced by three well-known wood-rotting fungi were carried in raw linseed oil and applied to cotton, polyester, and nylon. Only the red pigment produced visible color change on the textiles. Cotton and polyester showed the greatest color change when the pigments were dripped onto the fabric, while polyester showed the most color when the textile was submerged into the pigment solution. Unfortunately, the colors faded significantly for all the tests except the saturation test. This indicates that while natural oils may be excellent, nontoxic alternative carriers for DCM, the pigments are not stable within them except at very high concentrations, and therefore natural oils—including raw linseed oil—are not ideal for use in conjunction with these pigments.
      Citation: Coatings
      PubDate: 2017-09-23
      DOI: 10.3390/coatings7100152
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 153: A Guide to and Review of the Use of
           Multiwavelength Raman Spectroscopy for Characterizing Defective Aromatic
           Carbon Solids: from Graphene to Amorphous Carbons

    • Authors: Alexandre Merlen, Josephus Buijnsters, Cedric Pardanaud
      First page: 153
      Abstract: sp2 hybridized carbons constitute a broad class of solid phases composed primarily of elemental carbon and can be either synthetic or naturally occurring. Some examples are graphite, chars, soot, graphene, carbon nanotubes, pyrolytic carbon, and diamond-like carbon. They vary from highly ordered to completely disordered solids and detailed knowledge of their internal structure and composition is of utmost importance for the scientific and engineering communities working with these materials. Multiwavelength Raman spectroscopy has proven to be a very powerful and non-destructive tool for the characterization of carbons containing both aromatic domains and defects and has been widely used since the 1980s. Depending on the material studied, some specific spectroscopic parameters (e.g., band position, full width at half maximum, relative intensity ratio between two bands) are used to characterize defects. This paper is addressed first to (but not limited to) the newcomer in the field, who needs to be guided due to the vast literature on the subject, in order to understand the physics at play when dealing with Raman spectroscopy of graphene-based solids. We also give historical aspects on the development of the Raman spectroscopy technique and on its application to sp2 hybridized carbons, which are generally not presented in the literature. We review the way Raman spectroscopy is used for sp2 based carbon samples containing defects. As graphene is the building block for all these materials, we try to bridge these two worlds by also reviewing the use of Raman spectroscopy in the characterization of graphene and nanographenes (e.g., nanotubes, nanoribbons, nanocones, bombarded graphene). Counterintuitively, because of the Dirac cones in the electronic structure of graphene, Raman spectra are driven by electronic properties: Phonons and electrons being coupled by the double resonance mechanism. This justifies the use of multiwavelength Raman spectroscopy to better characterize these materials. We conclude with the possible influence of both phonon confinement and curvature of aromatic planes on the shape of Raman spectra, and discuss samples to be studied in the future with some complementary technique (e.g., high resolution transmission electron microscopy) in order to disentangle the influence of structure and defects.
      Citation: Coatings
      PubDate: 2017-09-25
      DOI: 10.3390/coatings7100153
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 154: Biodegradable Mg/HA/TiO2 Nanocomposites
           Coated with MgO and Si/MgO for Orthopedic Applications: A Study on the
           Corrosion, Surface Characterization, and Biocompatability

    • Authors: Shahrouz Zamani Khalajabadi, Aminudin Haji Abu, Norhayati Ahmad, Mohammed Kadir, Ahmad Ismail, Rozita Nasiri, Waseem Haider, Norizah Redzuan
      First page: 154
      Abstract: In the field of orthopedics, magnesium (Mg) and magnesium-based composites as biodegradable materials have attracted fundamental research. However, the medical applications of magnesium implants have been restricted owing to their poor corrosion resistance, especially in the physiological environment. To improve the corrosion resistance of Mg/HA/TiO2 nanocomposites, monolayer MgO and double-layer Si/MgO coatings were fabricated layer-by-layer on the surface of a nanocomposite using a powder metallurgy route. Then, coating thickness, surface morphology, and chemical composition were determined, and the corrosion behavior of the uncoated and coated samples was evaluated. Field-emission scanning electron microscopy (FE-SEM) micrographs show that an inner MgO layer with a porous microstructure and thickness of around 34 μm is generated on the Mg/HA/TiO2 nanocomposite substrate, and that the outer Si layer thickness is obtained at around 23 μm for the double-layered coated sample. Electrochemical corrosion tests and immersion corrosion tests were carried out on the uncoated and coated samples and the Si/MgO-coated nanocomposite showed significantly improved corrosion resistance compared with uncoated Mg/HA/TiO2 in simulated body fluid (SBF). Corrosion products comprising Mg(OH)2, HA, Ca3(PO4)2, and amorphous CaP components were precipitated on the immersed samples. Improved cytocompatibility was observed with coating as the cell viability ranged from 73% in uncoated to 88% for Si/MgO-coated Mg/HA/TiO2 nanocomposite after nine days of incubation.
      Citation: Coatings
      PubDate: 2017-09-26
      DOI: 10.3390/coatings7100154
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 155: Trajectory Optimization of Electrostatic
           Spray Painting Robots on Curved Surface

    • Authors: Wei Chen, Hao Liu, Yang Tang, Junjie Liu
      First page: 155
      Abstract: In this paper, a new practical electrostatic rotating bell (ESRB) cumulative rate model of painting is derived, and an experimental study on painting is carried out. First, the experimental method is used to obtain the radial thickness profile function of the spatial paint distribution of static spray. Then, a spatial trajectory-planning scheme for a spray-painting robot based on a rectangular model is presented. This method designs the spatial path of the spray-painting robot by using the cuboid model method after the optimal value is taken as the width d of the overlapping area of the two spray-painting strokes in the plane. The experimental results illustrate that the paint thickness basically meets the requirements, and the experimental results verify the effectiveness of the trajectory optimization method.
      Citation: Coatings
      PubDate: 2017-09-25
      DOI: 10.3390/coatings7100155
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 156: Microstructure, Mechanical and Corrosion
           Behaviors of CoCrFeNiAl0.3 High Entropy Alloy (HEA) Films

    • Authors: Libo Gao, Weibing Liao, Hongti Zhang, James Surjadi, Dong Sun, Yang Lu
      First page: 156
      Abstract: The HEA-CoCrFeNiAl0.3 thin film in this study has been successfully developed by radio frequency (RF) magnetron sputtering to meet the increasing demand in engineering applications. Its microstructure and surface profile were investigated accordingly. The as-synthesized HEA film was found to have a homogeneous element distribution and ultra-smooth surface, exhibiting a typical face-centered cubic (FCC) solid solution. The film showed better mechanical properties than its bulk counterpart, with a Young’s modulus and hardness of ~201.4 GPa and ~11.5 GPa, respectively. Furthermore, corrosion tests demonstrated decreased sensitivity to localized corrosion in comparison to the commercial 304 stainless steel in NaCl solution.
      Citation: Coatings
      PubDate: 2017-09-26
      DOI: 10.3390/coatings7100156
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 157: The Phase Evolution and Property of
           FeCoCrNiAlTix High-Entropy Alloying Coatings on Q253 via Laser Cladding

    • Authors: Bin He, Nannan Zhang, Danyang Lin, Yue Zhang, Fuyu Dong, Deyuan Li
      First page: 157
      Abstract: High-entropy alloys (HEAs) are emerging as a hot research frontier in the metallic materials field. The study on the effect of alloying elements on the structure and properties of HEAs may contribute to the progress of the research and accelerate the application in actual production. FeCoCrNiAlTix (x = 0, 0.25, 0.5, 0.75, and 1 in at.%, respectively) HEA coatings with different Ti concentrations were produced on Q235 steel via laser cladding. The constituent phases, microstructure, hardness, and wear resistance of the coatings were investigated by XRD, SEM, microhardness tester and friction-wear tester, respectively. The results show that the structure of the coating is a eutectic microstructure of FCC and BCC1 at x = 0. The structure of coatings consists of both proeutectic FCC phase and the eutectic structure of BCC1 and BCC2. With the continuous addition of Ti, the amount of eutectic structure decreases. The average hardness of the FeCoCrNiAlTix HEA coatings at x = 0, 0.25, 0.5, 0.75, and 1 are 432.73 HV, 548.81 HV, 651.03 HV, 769.20 HV, and 966.29 HV, respectively. The hardness of coatings increases with the addition of Ti, where the maximum hardness is achieved for the HEA at x = 1. The wear resistance of the HEA coatings is enhanced with the addition of Ti, and the main worn mechanism is abrasive wear.
      Citation: Coatings
      PubDate: 2017-09-28
      DOI: 10.3390/coatings7100157
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 158: Effect of Graphene Coating on the Heat
           Transfer Performance of a Composite Anti-/Deicing Component

    • Authors: Long Chen, Yidu Zhang, Qiong Wu
      First page: 158
      Abstract: The thermal conductivity of a graphene coating for anti-/deicing is rarely studied. This paper presents an improved anti-/deicing efficiency method for composite material anti-/deicing by using the heat-transfer characteristic of a graphene coating. An anti-/deicing experiment was conducted using the centrifugal force generated by a helicopter rotor. Results showed that the graphene coating can accelerate the internal heat transfer of the composite material, thereby improving the anti-icing and deicing efficiency of the helicopter rotor. The spraying process parameters, such as coating thickness and spraying pressure, were also studied. Results showed that reducing coating thickness and increasing spraying pressure are beneficial in preparing a graphene coating with high thermal conductivity. This study provides an experimental reference for the application of a graphene coating in anti-/deicing.
      Citation: Coatings
      PubDate: 2017-09-28
      DOI: 10.3390/coatings7100158
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 159: Thermoplastic Polyurethanes Stemming from
           Castor Oil: Green Synthesis and Their Application in Wood Bonding

    • Authors: Shaolong Li, Changlian Xu, Wenfeng Yang, Qingru Tang
      First page: 159
      Abstract: We report an efficient and green approach to synthesize a linear castor oil-based polyurethane (CPU) without using any solvent or catalyst. Diol monomers were first synthesized by the aminolysis reaction between castor oil and diamines; this was accomplished within 6 h at 130 °C. Polymerization of the diols and isocyanate was further confirmed by Fourier transform infrared (FTIR), 1H-nuclear magnetic resonance (1H-NMR), and gel permeation chromatography analyses. The resultant CPUs showed a good thermal stability with an initial degradation temperature higher than 300 °C, and their mechanical and wood bonding property can be modulated by the structures of diamine. In addition, the CPUs possessed a satisfying water resistance property with the water absorption amount lower than 2%. The green conversion of castor oil to thermoplastic polyurethane affords new opportunities in bio-based industries.
      Citation: Coatings
      PubDate: 2017-09-29
      DOI: 10.3390/coatings7100159
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 160: Prediction of the Corrosion Current Density
           in Reinforced Concrete Using a Self-Organizing Feature Map

    • Authors: Mehdi Nikoo, Łukasz Sadowski, Mohammad Nikoo
      First page: 160
      Abstract: A disadvantage of using linear polarization resistance (LPR) in the measurement of corrosion current density is the need to partially destroy a concrete cover. In this article, a new technique of predicting the corrosion current density in reinforced concrete using a self-organizing feature map (SOFM) is presented. For this purpose, air temperature, and also the parameters determined by the resistivity four-probe method and galvanostatic resistivity measurements, were employed as input variables. The corrosion current density, predicted by the destructive LPR method, was employed as the output variable. The weights of the SOFM were optimized using the genetic algorithm (GA). To evaluate the accuracy of the SOFM, a comparison with the radial basis function (RBF) and linear regression (LR) was performed. The results indicate that the SOFM–GA model has a higher ability, flexibility, and accuracy than the RBF and LR.
      Citation: Coatings
      PubDate: 2017-09-29
      DOI: 10.3390/coatings7100160
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 161: Novel Electrodeposited Ni-B/Y2O3 Composite
           Coatings with Improved Properties

    • Authors: Rana Shakoor, Umesh Waware, Kamran Ali, Ramazan Kahraman, Anton Popelka, Moinuddin Yusuf, Anwarul Hasan
      First page: 161
      Abstract: Ni-B/Y2O3 composite coatings were developed through an electrodeposition process to study the effect of addition of Y2O3 particles on structure, surface, thermal, mechanical, and anticorrosion properties of Ni-B coatings. It is revealed that parent crystal structure of Ni-B matrix is preserved by addition of Y2O3, however, a noticeable improvement in crystallinity is observed. The analysis of the surface exhibits formation of dense and nodular deposits in the two types of coatings, but incorporation of Y2O3 particles in Ni-B matrix has resulted in a noteworthy change in grain size and surface roughness. Thermal analysis of the surfaces indicates that Ni-B-Y2O3 composite coatings demonstrate superior thermal stability compared to Ni-B coatings. The nanoindentation analysis shows a significant enhancement in the mechanical characteristics of the Ni-B matrix by addition of Y2O3 particles. This may be contemplated as the result of grain refinement and dispersion hardening of the Ni-B matrix by the presence of hard Y2O3 particles. A decent improvement in the corrosion protection efficiency (73.6%) is also observed by addition of Y2O3 particles into Ni-B matrix. Simultaneous improvement of mechanical and anticorrosion properties suggests potential applications of Ni-B-Y2O3 coatings in oil and gas, automobile, and many other industries.
      Citation: Coatings
      PubDate: 2017-09-29
      DOI: 10.3390/coatings7100161
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 162: Electrochemical Behavior of Bilayer
           Thermal-Spray Coatings in Low-Temperature Corrosion Protection

    • Authors: Esmaeil Sadeghimeresht, Nicolaie Markocsan
      First page: 162
      Abstract: Cr3C2-NiCr coatings are greatly used to protect critical components in corrosive environments and to extend their lifetime and/or improve functional performance. However, the pores formed during spraying restrict the coating’s applicability area for many corrosion protection applications. To overcome this technical challenge, bilayer coatings have been developed, in which an additional layer (the so-called “intermediate layer”) is deposited on the substrate before spraying the Cr3C2-NiCr coating (the so-called “top layer”). The corrosion behavior of the bilayer coating depends on the composition and microstructure of each layer. In the present work, different single-layer coatings (i.e., Cr3C2-NiCr, Fe- and Ni-based coatings) were initially sprayed by a high-velocity air fuel (HVAF) process. Microstructure analysis, as well as electrochemical tests, for example, open-circuit potential (OCP) and polarization tests, were performed. The potential difference (ΔE) had a great influence on galvanic corrosion between the top and intermediate layers, and thus, the coatings were ranked based on the OCP values (from high to low) as follows: NiCoCrAlY > NiCr > Cr3C2-NiCr > NiAl > Fe-based coatings (alloyed with Cr) > pure Ni. The Ni-based coatings were chosen to be further used as intermediate layers with the Cr3C2-NiCr top layer due to their capabilities to show high OCP. The corrosion resistance (Rp) of the bilayer coatings was ranked (from high to low) as follows: NiCoCrAlY/Cr3C2-NiCr > NiCr/Cr3C2-NiCr > NiAl/Cr3C2-NiCr > Ni/Cr3C2-NiCr. It was shown that splat boundaries and interconnected pores are detrimental for corrosion resistance, however, a sufficient reservoir of protective scale-forming elements (such as Cr or/and Al) in the intermediate layer can significantly improve the corrosion resistance.
      Citation: Coatings
      PubDate: 2017-09-30
      DOI: 10.3390/coatings7100162
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 163: Influence of Coating Formulation on Its
           Mechanical Properties and Cracking Resistance

    • Authors: Laurence Podgorski, Mari de Meijer, Jean-Denis Lanvin
      First page: 163
      Abstract: The mechanical properties of coatings strongly influence wood coatings’ performance, as coatings may be stressed by dimensional variations of wood when exposed outdoors. Within the European project SERVOWOOD (2014–2016), the influence of coating formulation on mechanical properties and cracking resistance has been studied. Several acrylic and alkyd formulations with different pigment volume concentrations (PVCs), with and without UV protection have been applied on pine samples and exposed to artificial weathering (EN 927-6) for 12 weeks. Persoz hardness of coatings applied on wood was assessed before and after weathering. Tensile tests on free films have been carried out at −10 °C, 20 °C, and 45 °C. For each formulation, elastic modulus, tensile strength, and strain at break have been determined for the three test temperatures. For each test temperature, there was no correlation between the elastic modulus and strain at break, nor between tensile strength and strain at break. The results showed a relation between Persoz hardness and elastic modulus. The best performing formulation had a mean elastic modulus at room temperature lower than 400 MPa and a mean strain at break higher than 30%.
      Citation: Coatings
      PubDate: 2017-09-30
      DOI: 10.3390/coatings7100163
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 164: Chemical Vapor Deposition of Bi-Te-Ni-Fe on
           Magnesium Oxide Substrate and Its Seebeck Effect

    • Authors: Yong Gan, Anan Hamdan, Jeremy Gan, Mingheng Li
      First page: 164
      Abstract: In this work, a Bi-Te-Ni-Fe complex coating material was obtained on magnesium oxide substrate by a single step ambient pressure chemical vapor deposition (CVD). Nickel acetate, bismuth acetate, iron (III) nitrate, and tellurium (IV) chloride dissolved in N,N-dimethylformamide (DMF) served as the metal sources for Ni, Bi, Fe, and Te, respectively. Hydrogen was used as the carrier gas. The substrate was kept at 500 °C in a quartz tube reaction chamber. The chemical vapor deposition time was two hours. Scanning electron microscopic observation revealed porous morphology of the deposited material with a needle-like submicron fine structure. These needle-like entities form networks with fairly uniform distribution on the substrate. Thermoelectric property test showed that the coating is p-type with a Seebeck coefficient of 179 µV/K. Time-dependent potential data were obtained to show the sensitivity of the Seebeck effect to temperature changes.
      Citation: Coatings
      PubDate: 2017-10-01
      DOI: 10.3390/coatings7100164
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 165: Multilayer CVD Diamond Coatings in the
           Machining of an Al6061-15 Vol % Al2O3 Composite

    • Authors: Mohammadmehdi Shabani, Joaquim Sacramento, Filipe Oliveira, Rui Silva
      First page: 165
      Abstract: Ceramic cutting inserts coated with ten-fold alternating micro- and nanocrystalline diamond (MCD/NCD) layers grown by hot filament chemical vapor deposition (CVD) were tested in the machining of an Al based metallic matrix composite (MMC) containing 15 vol % Al2O3 particles. Inserts with total coating thicknesses of approximately 12 µm and 24 µm were produced and used in turning: cutting speed (v) of 250 to 1000 m·min−1; depth of cut (DOC) from 0.5 to 3 mm and feed (f) between 0.1 and 0.4 mm·rev−1. The main cutting force increases linearly with DOC (ca. 294 N per mm) and with feed (ca. 640 N per mm·rev−1). The thicker coatings work within the following limits: DOC up to 1.5 mm and maximum speeds of 750 m·min−1 for feeds up to 0.4 mm·rev−1. Flank wear is predominant but crater wear is also observed due to the negative tool normal rake. Layer-by-layer wear of the tool rake, and not total delamination from the substrate, evidenced one of the advantages of using a multilayer design. The MCD/NCD multilayer diamond coated indexable inserts have longer tool life than most CVD diamond systems and behave as well as most polycrystalline diamond (PCD) tools.
      Citation: Coatings
      PubDate: 2017-10-03
      DOI: 10.3390/coatings7100165
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 166: A Novel Image Segmentation Approach for
           Microstructure Modelling

    • Authors: Michael Watson, Matthew Marshall
      First page: 166
      Abstract: Microstructure models are used to investigate bulk properties of a material given images of its microstructure. Through their use the effect of microstructural features can be investigated independently. Processes can then be optimised to give the desired selection of microstructural features. Currently automatic methods of segmenting SEM images either miss cracks leading to large overestimates of properties or use unjustifiable methods to select a threshold point which class cracks as porosity leading to over estimates of porosity. In this work, a novel automatic image segmentation method is presented which produces maps for each phase in the microstructure and an additional phase of cracks. The selection of threshold points is based on the assumption that the brightness values for each phase should be normally distributed. The image segmentation method has been compared to other available methods and shown to be as or more repeatable with changes of brightness and contrast of the input image than relevant alternatives. The resulting modelling route is able to predict density and specific heat to within experimental error, while the expected under predictions for thermal conductivity are observed.
      Citation: Coatings
      PubDate: 2017-10-04
      DOI: 10.3390/coatings7100166
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 167: Enhanced Efficiency of Dye-Sensitized Solar
           Counter Electrodes Consisting of Two-Dimensional Nanostructural Molybdenum
           Disulfide Nanosheets Supported Pt Nanoparticles

    • Authors: Chao-Kuang Cheng, Jeng-Yu Lin, Kai-Chen Huang, Tsung-Kuang Yeh, Chien-Kuo Hsieh
      First page: 167
      Abstract: This paper reports architecturally designed nanocomposites synthesized by hybridizing the two-dimensional (2D) nanostructure of molybdenum disulfide (MoS2) nanosheet (NS)-supported Pt nanoparticles (PtNPs) as counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). MoS2 NSs were prepared using the hydrothermal method; PtNPs were subsequently reduced on the MoS2 NSs via the water–ethylene method to form PtNPs/MoS2 NSs hybrids. The nanostructures and chemical states of the PtNPs/MoS2 NSs hybrids were characterized by high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. Detailed electrochemical characterizations by electrochemical impedance spectroscopy, cyclic voltammetry, and Tafel-polarization measurement demonstrated that the PtNPs/MoS2 NSs exhibited excellent electrocatalytic activities, afforded a higher charge transfer rate, a decreased charge transfer resistance, and an improved exchange current density. The PtNPs/MoS2 NSs hybrids not only provided the exposed layers of 2D MoS2 NSs with a great deal of catalytically active sites, but also offered PtNPs anchored on the MoS2 NSs enhanced I3− reduction. Accordingly, the DSSCs that incorporated PtNPs/MoS2 NSs CE exhibited an outstanding photovoltaic conversion efficiency (PCE) of 7.52%, which was 8.7% higher than that of a device with conventional thermally-deposited platinum CE (PCE = 6.92%).
      Citation: Coatings
      PubDate: 2017-10-13
      DOI: 10.3390/coatings7100167
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 168: Chitosan Coating on Silica-Modified
           Polymethyl Methacrylate for Dental Applications

    • Authors: Mieszko Więckiewicz, Eric Wolf, Katarzyna Walczak, Heike Meissner, Klaus Boening
      First page: 168
      Abstract: Chitosan is a cationic natural polymer that is widely used as a topical dressing in wound management. Temporary coatings of removable denture bases with chitosan might be useful as supportive treatment in oral medicine. The aim of this study was to analyze the thickness, uniformity, and adhesive strength of chitosan coatings on simulated denture bases made from polymethyl methacrylate (PMMA). According to a standardized protocol, 20 PMMA cylinders (13 mm diameter, 5 mm in height) as well as 20 cubes (a = 25 mm) with intaglio U-shaped profiles were manufactured to simulate average sized alveolar ridges. Cylinders as well as cubes were divided into four test series with n = 5 each. After sandblasting with silica-modified alumina, one frontal surface of the PMMA cylinders and the intaglio surfaces of the U-shaped profiles was coated with chitosan acetate solution according to the following protocols: one layer of 2% chitosan acetate solution (test series I), one layer of 4% chitosan acetate solution (test series II), two layers of 2% chitosan acetate solution (test series III), and two layers of 4% chitosan acetate solution (test series IV). After drying and neutralization with NaOH, each cube was cut transversely and the coating thickness across the U-shaped profile assessed with a light microscope. Adhesive strength was evaluated by simulated tooth brushing and the loss of chitosan coating was evaluated qualitatively. Statistical analysis used Friedman ANOVA test for dependent samples and Kruskal-Wallis test for independent samples, post-hoc Dunn’s test (p < 0.05), and binomial test (p = 0.05). The mean chitosan coating thicknesses in the depth of the U-profiles were 71 µm (test series I), 77 µm (test series II), 121 µm (test series III), and 517 µm (test series VI). The thickness continuously decreased with rising angulation of the U-profile side walls. In test series I, the chitosan coating thickness significantly dropped above a 30° angulation of the U-profile side walls. In test series II to IV, the chitosan thickness drop was not statistically significant at angulations of 30° and 60°, but was at 90° angulation of the U-profile side walls. Adhesion strength was rated fair to good and did not differ significantly among the four test series. The coating technique described revealed chitosan layers with overall good adhesion strength but differing thicknesses. Coatings with one or two layers of 4% chitosan acetate solution allowed a relatively uniform chitosan thickness and thus might be usable in oral medicine.
      Citation: Coatings
      PubDate: 2017-10-13
      DOI: 10.3390/coatings7100168
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 169: Deposition of Photocatalytic TiO2 Coating by
           Modifying the Solidification Pathway in Plasma Spraying

    • Authors: Kui Wen, Min Liu, Xuezhang Liu, Chunming Deng, Kesong Zhou
      First page: 169
      Abstract: The deposition of photocatalytic TiO2 coatings with plasma spraying is attractive for large-scale applications due to its low cost and simplicity, but it is still a challenge to obtain a TiO2 coating with high anatase content. The solidification pathway of inflight melted particles was investigated in the present paper, and TiO2 coatings with enhanced photocatalytic activity were obtained without a significant loss of the microhardness. The coating microstructure, phase composition, and crystallite size were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Photocatalytic performance was evaluated by decomposing an aqueous solution of methylene blue. Results showed that the anatase content in TiO2 coating was augmented to 19.9% from 4%, and the time constant of the activity was increased to 0.0046 h−1 from 0.0017 h−1.
      Citation: Coatings
      PubDate: 2017-10-13
      DOI: 10.3390/coatings7100169
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 170: Marching-on-in-Degree Time-Domain Integral
           Equation Solver for Transient Electromagnetic Analysis of Graphene

    • Authors: Quanquan Wang, Huazhong Liu, Yan Wang, Zhaoneng Jiang
      First page: 170
      Abstract: The marching-on-in-degree (MOD) time-domain integral equation (TDIE) solver for the transient electromagnetic scattering of the graphene is presented in this paper. Graphene’s dispersive surface impedance is approximated using rational function expressions of complex conjugate pole-residue pairs with the vector fitting (VF) method. Enforcing the surface impedance boundary condition, TDIE is established and solved in the MOD scheme, where the temporal surface impedance is carefully convoluted with the current. Unconditionally stable transient solution in time domain can be ensured. Wide frequency band information is obtained after the Fourier transform of the time domain solution. Numerical results validate the proposed method.
      Citation: Coatings
      PubDate: 2017-10-17
      DOI: 10.3390/coatings7100170
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 171: Atmosphereic Pressure Plasma Coating of Wood
           and MDF with Polyester Powder

    • Authors: Robert Köhler, Philipp Sauerbier, Holger Militz, Wolfgang Viöl
      First page: 171
      Abstract: In this study, polyester powder based on iso- and teraphthalic acid was deposited with an atmospheric plasma jet. The powder was fed into the effluent plasma zone and deposited on European beech wood (Fagus sylvatica L.), Grand fir (Abies grandis Lindl.) and medium density fiberboard (MDF). The substrates were annealed subsequent to the coating process. To exclude decomposition of the polyester layers by the plasma treatment, the surface chemistry of the layers has been examined by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) and compared with the polyester powder reference. Furthermore, topographical investigations were carried out using laser scanning microscopy (LSM). Adhesive strength of the layers was evaluated by dolly test and gloss measurements with a goniophotometer. The deposited layers showed no chemical changes compared to the reference. The adhesive strength of the layer met practical requirements of >1 MPa. It was demonstrated that the deposition of a macroscopic layer is possible without a pretreatment or the usage of additives. Therefore this coating process by atmospheric pressure plasma for wood and wood based materials could represent an environmental-friendly alternative to conventional coating methods.
      Citation: Coatings
      PubDate: 2017-10-17
      DOI: 10.3390/coatings7100171
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 172: Efficacy of Hydrophobic Coatings in
           Protecting Oak Wood Surfaces during Accelerated Weathering

    • Authors: Miloš Pánek, Eliška Oberhofnerová, Aleš Zeidler, Přemysl Šedivka
      First page: 172
      Abstract: The durability of transparent coatings applied to an oak wood exterior is relatively low due to its anatomic structure and chemical composition. Enhancement of the protection of oak wood against weathering using transparent hydrophobic coatings is presented in this study. Oak wood surfaces were modified using UV-stabilizers, hindered amine light stabilizer (HALS), and ZnO and TiO2 nanoparticles before the application of a commercial hydrophobic topcoat. A transparent oil-based coating was used as a control coating system. The artificial weathering test lasted 6 weeks and colour, gloss, and contact angle changes were regularly evaluated during this period. The changes in the microscopic structure were studied with confocal laser scanning microscopy. The results proved limited durability against weathering of both tested hydrophobic coatings. The formation of micro-cracks causing the leaching of degraded wood compounds and discolouration of oak wood were observed after 1 or 3 weeks of the weathering test. Until then, an oil-based coating film had protected the wood sufficiently, but after 6 weeks the wood was fully defoliated to its non-homogenous thickness, which was caused by the presence of large oak vessels, and by the effects of specific oak tannins. Using transparent hydrophobic coatings can prolong the service life of the exteriors of wood products by decreasing their moisture content. Without proper construction protection against rainwater, the hydrophobic coating itself cannot guarantee the preservation of the natural appearance of wood exteriors.
      Citation: Coatings
      PubDate: 2017-10-18
      DOI: 10.3390/coatings7100172
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 173: Thermal Conductivity and Wear Behavior of
           HVOF-Sprayed Fe-Based Amorphous Coatings

    • Authors: Haihua Yao, Zheng Zhou, Liang Wang, Zhen Tan, Dingyong He, Lidong Zhao
      First page: 173
      Abstract: To protect aluminum parts in vehicle engines, metal-based thermal barrier coatings in the form of Fe59Cr12Nb5B20Si4 amorphous coatings were prepared by high velocity oxygen fuel (HVOF) spraying under two different conditions. The microstructure, thermal transport behavior, and wear behavior of the coatings were characterized simultaneously. As a result, this alloy shows high process robustness during spraying. Both Fe-based coatings present dense, layered structure with porosities below 0.9%. Due to higher amorphous phase content, the coating H-1 exhibits a relatively low thermal conductivity, reaching 2.66 W/(m·K), two times lower than the reference stainless steel coating (5.85 W/(m·K)), indicating a good thermal barrier property. Meanwhile, the thermal diffusivity of amorphous coatings display a limited increase with temperature up to 500 °C, which guarantees a steady and wide usage on aluminum alloy. Furthermore, the amorphous coating shows better wear resistance compared to high carbon martensitic GCr15 steel at different temperatures. The increased temperature accelerating the tribological reaction, leads to the friction coefficient and wear rate of coating increasing at 200 °C and decreasing at 400 °C.
      Citation: Coatings
      PubDate: 2017-10-19
      DOI: 10.3390/coatings7100173
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 174: Effects of the Amount and Type of Diol Ring
           Openers on the Properties of Oligolactide Acrylates for UV-Curable
           Printing Inks

    • Authors: Santi Kulsiriswad, Kawee Srikulkit, Onusa Saravari
      First page: 174
      Abstract: This study aimed to synthesize low viscosity oligolactide acrylates for UV-curable inks from oligolactide diols. Firstly, low molecular weight oligolactide diols were prepared by ring opening reaction of L-lactide with diols. Oligolactide acrylates were then synthesized by functionalizing the oligolactide diols with acrylic acid. In this study, three diol ring openers having short and long alkyl chain length were used to investigate the effects of the amount and type of diols on the properties of the oligolactide acrylates. The obtained oligomers were characterized, and the viscosities of oligolactide acrylates were measured. Results showed that oligolactide acrylates were successfully synthesized in all cases of ring openers, as confirmed by 1H-NMR (proton nuclear magnetic resonance spectroscopy) and FTIR (Fourier transform infrared spectroscopy). An increase in the alkyl chain length of the ring openers resulted in oligomers with lower viscosity and a decrease in Tg. Following that, the obtained oligolactide acrylates were employed for the formulation of UV-curable screen printing inks and their properties were investigated. Results showed that the inks formulated from oligomers with lower molecular weight exhibited better ink flow. Additionally, all ink films cured by UV radiation were very flexible with excellent adhesion, high impact resistance, and excellent water resistance.
      Citation: Coatings
      PubDate: 2017-10-20
      DOI: 10.3390/coatings7100174
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 175: Effect of Coating Palm Oil Clinker Aggregate
           on the Engineering Properties of Normal Grade Concrete

    • Authors: Fuad Abutaha, Hashim Abdul Razak, Hussein Ibrahim
      First page: 175
      Abstract: Palm oil clinker (POC) is a waste material generated in large quantities from the palm oil industry. POC, when crushed, possesses the potential to serve as an aggregate for concrete production. Experimental investigation on the engineering properties of concrete incorporating POC as aggregate and filler material was carried out in this study. POC was partially and fully used to replace natural coarse aggregate. The volumetric replacements used were 0%, 20%, 40%, 60%, 80%, and 100%. POC, being highly porous, negatively affected the fresh and hardened concrete properties. Therefore, the particle-packing (PP) method was adopted to measure the surface and inner voids of POC coarse aggregate in the mixtures at different substitution levels. In order to enhance the engineering properties of the POC concrete, palm oil clinker powder (POCP) was used as a filler material to fill up and coat the surface voids of POC coarse, while the rest of the mix constituents were left as the same. Fresh and hardened properties of the POC concrete with and without coating were determined, and the results were compared with the control concrete. The results revealed that coating the surface voids of POC coarse with POCP significantly improved the engineering properties as well as the durability performance of the POC concrete. Furthermore, using POC as an aggregate and filler material may reduce the continuous exploitation of aggregates from primary sources. Also, this approach offers an environmental friendly solution to the ongoing waste problems associated with palm oil waste material.
      Citation: Coatings
      PubDate: 2017-10-21
      DOI: 10.3390/coatings7100175
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 176: Evaluation of Selected Properties of Alder
           Wood as Functions of Sanding and Coating

    • Authors: Emilia-Adela Salca, Tomasz Krystofiak, Barbara Lis
      First page: 176
      Abstract: The objective of this study was to optimize the sanding and coating processes of black alder wood to promote and support its use in furniture manufacturing. Two criteria have been applied for process optimization, namely, the minimum surface roughness of the samples and power consumption during sanding as a function of various sanding systems. The surface roughness of the sanded specimens and the power consumption during sanding strongly depends on the grit size used. Two eco-varnishes were applied to the samples by spraying. Moreover, the effect of the surface preparation and varnish type on the coating properties expressed by the varnish layer adherence to the substrate and surface glossiness was evaluated. For better glossiness values, the UV-cured varnish was preferred. The sanding with a grit sequence of 60, 120, and 150 grit size abrasives was found to be optimal when applied to black alder wood, and it is recommended to obtain performant UV-coated wood surfaces for furniture products.
      Citation: Coatings
      PubDate: 2017-10-21
      DOI: 10.3390/coatings7100176
      Issue No: Vol. 7, No. 10 (2017)
       
  • Coatings, Vol. 7, Pages 177: Antimicrobial Films Based on Chitosan and
           Methylcellulose Containing Natamycin for Active Packaging Applications

    • Authors: Serena Santonicola, Verónica García Ibarra, Raquel Sendón, Raffaelina Mercogliano, Ana Rodríguez-Bernaldo de Quirós
      First page: 177
      Abstract: Biodegradable polymers are gaining interest as antimicrobial carriers in active packaging. In the present study, two active films based on chitosan (1.5% w/v) and methylcellulose (3% w/v) enriched with natamycin were prepared by casting. The antimicrobial’s release behavior was evaluated by immersion of the films in 95% ethanol (v/v) at different temperatures. The natamycin content in the food simulant was determined by reversed-high performance liquid chromatography with diode-array detection (HPLC-DAD). The apparent diffusion (DP) and partition (KP/S) coefficients were calculated using a mathematical model based on Fick’s Second Law. Results showed that the release of natamycin from chitosan based film (DP = 3.61 × 10−13 cm2/s) was slower, when compared with methylcellulose film (DP = 3.20 × 10−8 cm2/s) at the same temperature (p < 0.05). To evaluate the antimicrobial efficiency of active films, cheese samples were completely covered with the films, stored at 20 °C for 7 days, and then analyzed for moulds and yeasts. Microbiological analyses showed a significant reduction in yeasts and moulds (7.91 log CFU/g) in samples treated with chitosan active films (p < 0.05). The good compatibility of natamycin with chitosan, the low Dp, and antimicrobial properties suggested that the film could be favorably used in antimicrobial packagings.
      Citation: Coatings
      PubDate: 2017-10-24
      DOI: 10.3390/coatings7100177
      Issue No: Vol. 7, No. 10 (2017)
       
 
 
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