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Coatings, Volume 9, Issue 11 (November 2019) – 80 articles

Cover Story (view full-size image): The effect of cross-linking with transglutaminase (TG) of two varieties of quinoa protein isolate (Chenopodium quinoa) [Willd (QW), and Pasankalla (QP)] on the physicochemical and barrier properties of edible films based on chitosan (CT)-quinoa protein were evaluated. TG interacted with lysine of QW and QP reducing the range of water vapor permeability of the different CT:quinoa protein films to 2.42–4.69 × 10−11 g cm Pa−1 cm−2 s−1, and also the CT:QP (1:10, w/w) film showed reduced surface roughness to 4.4 ± 0.3 nm. From the sorption isotherm addition of TG to CT-QW films improved their stability [monolayer (Xm) = 0.13 ± 0.02 %]. Films with a higher amount of cross-linking showed the highest improvement in the evaluated physical properties, but interactions among proteins that were catalyzed by TG depended on the protein source and profile. View this pap
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15 pages, 5732 KiB  
Article
Preparation and Performance Optimization of Original Aluminum Ash Coating Based on Plasma Spraying
by Hongjun Ni, Jiaqiao Zhang, Shuaishuai Lv, Xingxing Wang, Yu Zhu and Tao Gu
Coatings 2019, 9(11), 770; https://doi.org/10.3390/coatings9110770 - 19 Nov 2019
Cited by 12 | Viewed by 2874
Abstract
As an industrial solid waste, the original aluminum ash (OAA) will cause serious pollution to the air and soil. How to reuse the OAA has been a research difficulty. Thus, a method of preparing a plasma spray powder using OAA is proposed. The [...] Read more.
As an industrial solid waste, the original aluminum ash (OAA) will cause serious pollution to the air and soil. How to reuse the OAA has been a research difficulty. Thus, a method of preparing a plasma spray powder using OAA is proposed. The OAA was hydrolyzed and ball milled, and the flowability of original aluminum ash spray powder (OAASP) was evaluated by the angle of repose. The coating properties were determined via analyzing the microstructure and the phase of the coating, and the effects of plasma spray parameters on the coating properties were investigated by the orthogonal experiment to optimize spray parameters. The results show that the angle of repose of OAASP after granulation was less than 40°, which met the requirements of plasma spraying. When the spraying current was 600 A, the spraying voltage was 60 V, the main gas flow was 33 slpm, and the powder flow rate was 22 g/min, and the prepared original aluminum ash coating (OAAC) had excellent comprehensive performance. After the spraying process parameters were optimized, the microhardness of the coating was 606.54 HV, which is about twice the hardness of the substrate; the abrasion rate was 12.86 × 10−3 g/min; the porosity was 0.16%; and the adhesive strength was 16 MPa. When the amount of Al2O3 added was 50%, the hardness of the coating was increased by 17.61%. Full article
(This article belongs to the Section Surface Characterization, Deposition and Modification)
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14 pages, 2666 KiB  
Article
ZnO Nanocrystal-Based Chloroform Detection: Density Functional Theory (DFT) Study
by H. Y. Ammar, H. M. Badran, Ahmad Umar, H. Fouad and Othman Y. Alothman
Coatings 2019, 9(11), 769; https://doi.org/10.3390/coatings9110769 - 19 Nov 2019
Cited by 16 | Viewed by 3516
Abstract
We investigated the detection of chloroform (CHCl3) using ZnO nanoclusters via density functional theory calculations. The effects of various concentrations of CHCl3, as well as the deposition of O atoms, on the adsorption over ZnO nanoclusters were analyzed via [...] Read more.
We investigated the detection of chloroform (CHCl3) using ZnO nanoclusters via density functional theory calculations. The effects of various concentrations of CHCl3, as well as the deposition of O atoms, on the adsorption over ZnO nanoclusters were analyzed via geometric optimizations. The calculated difference between the highest occupied molecular orbital and the lowest unoccupied molecular orbital for ZnO was 4.02 eV. The most stable adsorption characteristics were investigated with respect to the adsorption energy, frontier orbitals, elemental positions, and charge transfer. The results revealed that ZnO nanoclusters with a specific geometry and composition are promising candidates for chloroform-sensing applications. Full article
(This article belongs to the Special Issue Mesoporous Metal Oxide Films)
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14 pages, 6115 KiB  
Article
Influence of Aluminum Laser Ablation on Interfacial Thermal Transfer and Joint Quality of Laser Welded Aluminum–Polyamide Assemblies
by Adham Al-Sayyad, Julien Bardon, Pierre Hirchenhahn, Regis Vaudémont, Laurent Houssiau and Peter Plapper
Coatings 2019, 9(11), 768; https://doi.org/10.3390/coatings9110768 - 19 Nov 2019
Cited by 11 | Viewed by 3414
Abstract
Laser assisted metal–polymer joining (LAMP) is a novel assembly process for the development of hybrid lightweight products with customized properties. It was already demonstrated that laser ablation of aluminum alloy Al1050 (Al) prior to joining with polyamide 6.6 (PA) has significant influence on [...] Read more.
Laser assisted metal–polymer joining (LAMP) is a novel assembly process for the development of hybrid lightweight products with customized properties. It was already demonstrated that laser ablation of aluminum alloy Al1050 (Al) prior to joining with polyamide 6.6 (PA) has significant influence on the joint quality, manifested in the joint area. However, profound understanding of the factors affecting the joint quality was missing. This work investigates the effects of laser ablation on the surface properties of Al, discusses their corresponding impact on the interfacial thermal transfer between the joining partners, and evaluates their effects on the joint quality. Samples ablated with different parameters, resulting in a range from low- to high-quality joints, were selected, and their surface properties were analyzed by using 2D profilometry, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDX). In order to analyze the effects of laser ablation parameters on the interfacial thermal transfer between metal and polymer, a model two-layered system was analyzed, using laser flash analysis (LFA), and the thermal contact resistance (TCR) was quantified. Results indicate a strong influence of laser-ablation parameters on the surface structural and morphological properties, influencing the thermal transfer during the laser welding process, thus affecting the joint quality and its resistance to shear load. Full article
(This article belongs to the Special Issue Surface Treatment by Laser-Assisted Techniques)
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15 pages, 2577 KiB  
Article
ZnO (Ag-N) Nanorods Films Optimized for Photocatalytic Water Purification
by Luis Sanchez, Carlos Castillo, Willy Cruz, Bryan Yauri, Miguel Sosa, Clemente Luyo, Roberto Candal, Silvia Ponce and Juan M. Rodriguez
Coatings 2019, 9(11), 767; https://doi.org/10.3390/coatings9110767 - 19 Nov 2019
Cited by 8 | Viewed by 2957
Abstract
ZnO nanorods (NRs) films, nitrogen-doped (ZnO:N), and ZnO doped with nitrogen and decorated with silver nanostructures (ZnO:N-Ag) NRs films were vertically supported on undoped and N doped ZnO seed layers by a wet chemical method. The obtained films were characterized structurally by X-ray [...] Read more.
ZnO nanorods (NRs) films, nitrogen-doped (ZnO:N), and ZnO doped with nitrogen and decorated with silver nanostructures (ZnO:N-Ag) NRs films were vertically supported on undoped and N doped ZnO seed layers by a wet chemical method. The obtained films were characterized structurally by X-ray diffraction. Morphological and elemental analysis was performed by scanning electron microscopy, including an energy dispersive X-ray spectroscopy facility and their optical properties by Ultraviolet-Visible Spectroscopy. Analysis performed in the NRs films showed that the nitrogen content in the seed layer strongly affected their structure and morphology. The mean diameter of ZnO NRs ranged from 70 to 190 nm. As the nitrogen content in the seed layer increased, the mean diameter of ZnO:N NRs increased from 132 to 250 nm and the diameter dispersion decreased. This diameter increase occurs simultaneously with the incorporation of nitrogen into the ZnO crystal lattice and the increase in the volume of the unit cell, calculated using the X-ray diffraction patterns and confirmed by a slight shift in the XRD angle. The diffractograms indicated that the NRs have a hexagonal wurtzite structure, with preferential growth direction along the c axis. The SEM images confirmed the presence of metallic silver in the form of nanoparticles dispersed on the NRs films. Finally, the degradation of methyl orange (MO) in an aqueous solution was studied by UV-vis irradiation of NRs films contained in the bulk of aqueous MO solutions. We found a significant enhancement of the photocatalytic degradation efficiency, with ZnO:N-Ag NRs film being more efficient than ZnO:N NRs film, and the latter better than the ZnO NRs film. Full article
(This article belongs to the Special Issue Photocatalytic Thin Films)
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13 pages, 1362 KiB  
Article
A Facile Way to Improve the Performance of Perovskite Solar Cells by Toluene and Diethyl Ether Mixed Anti-Solvent Engineering
by Haifeng Yang, Hui Wang, Jincheng Zhang, Jingjing Chang and Chunfu Zhang
Coatings 2019, 9(11), 766; https://doi.org/10.3390/coatings9110766 - 18 Nov 2019
Cited by 12 | Viewed by 6017
Abstract
Solvent engineering is one of the most widely applied preparation methods for the high- quality perovskite films. In this method, the choice of anti-solvent plays a very important role to improve the perovskite crystal quality. Here, we report a facile way to regulate [...] Read more.
Solvent engineering is one of the most widely applied preparation methods for the high- quality perovskite films. In this method, the choice of anti-solvent plays a very important role to improve the perovskite crystal quality. Here, we report a facile way to regulate the crystal quality of perovskite film by adjusting the ratio of toluene and diethyl ether in the mixed anti-solvent. Through the combination of characterization and measurements including scanning electron microscopy, the atomic force microscopy, X-ray diffraction, and the steady-state photoluminescence spectra, it reveals that the quality of perovskite films is obviously improved when the volume ratio of toluene to diethyl ether in the mixed anti-solvent is 1:1. The optimal device obtains power conversion efficiency of 16.96% with a short-circuit current density of 20.60 mA/cm2, an open-circuit voltage of 1.03 V, and a fill factor of 79.96%. At the same time, the device shows negligible current–voltage hysteresis and steady power output. Moreover, the stability of PSCs is significantly enhanced due to the perovskite film quality improvement by adopting 50% toluene mixed anti-solvent. Full article
(This article belongs to the Special Issue Achievements and Challenges in Thin Film Solar Cells)
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12 pages, 5455 KiB  
Article
Study on the Damage Mechanism of TiN/Ti Coatings Based on Multi-Directional Impact
by Zhihao Fang, Jiao Chen, Weifeng He, Zhufang Yang, Zhanwei Yuan, Mingrui Geng and Guangyu He
Coatings 2019, 9(11), 765; https://doi.org/10.3390/coatings9110765 - 18 Nov 2019
Cited by 14 | Viewed by 2437
Abstract
TiN/Ti coatings have great application potential in improving aero-engine server lives in a dusty environment. However, the damage behavior and mechanism of the coating and substrate under high impact speed and multi-direction loading conditions has scarcely been investigated. In this paper, TiN/Ti coatings [...] Read more.
TiN/Ti coatings have great application potential in improving aero-engine server lives in a dusty environment. However, the damage behavior and mechanism of the coating and substrate under high impact speed and multi-direction loading conditions has scarcely been investigated. In this paper, TiN/Ti coatings were deposited on Ti6Al4V alloys by a magnetic filter cathode vacuum arc. Multi-directional impact tests were carried out by a gas gun system at, 45°, 60°, and 90° with a velocity of 330 m/s. The damage behaviors and mechanisms of the TiN/Ti coatings were investigated and revealed by researching the damage morphology, crack propagation, and stress distribution. The results show that plastic deformation occurs both in the coatings and the substrates under high speed impacting. Cracks extend vertically downward in the TiN layer first and are deflected at the Ti layer when the driving force is not enough. Circular cracks and radical cracks are found to form network cracks on the surface of the coating and the shear stress loaded by the particles, which drives cracks’ propagation is the main reason for the peeling off on the coatings. Full article
(This article belongs to the Special Issue Erosion of Nanostructured Coatings)
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12 pages, 2663 KiB  
Article
A Printable Paste Based on a Stable n-Type Poly[Ni-tto] Semiconducting Polymer
by Roman Tkachov, Lukas Stepien, Moritz Greifzu, Anton Kiriy, Nataliya Kiriy, Tilman Schüler, Tino Schmiel, Elena López, Frank Brückner and Christoph Leyens
Coatings 2019, 9(11), 764; https://doi.org/10.3390/coatings9110764 - 18 Nov 2019
Cited by 3 | Viewed by 2819
Abstract
Polynickeltetrathiooxalate (poly[Ni-tto]) is an n-type semiconducting polymer having outstanding thermoelectric characteristics and exhibiting high stability under ambient conditions. However, its insolubility limits its use in organic electronics. This work is devoted to the production of a printable paste based on a poly[Ni-tto]/PVDF composite [...] Read more.
Polynickeltetrathiooxalate (poly[Ni-tto]) is an n-type semiconducting polymer having outstanding thermoelectric characteristics and exhibiting high stability under ambient conditions. However, its insolubility limits its use in organic electronics. This work is devoted to the production of a printable paste based on a poly[Ni-tto]/PVDF composite by thoroughly grinding the powder in a ball mill. The resulting paste has high homogeneity and is characterized by rheological properties that are well suited to the printing process. High-precision dispenser printing allows one to apply both narrow lines and films of poly[Ni-tto]-composite with a high degree of smoothness. The resulting films have slightly better thermoelectric properties compared to the original polymer powder. A flexible, fully organic double-leg thermoelectric generator with six thermocouples was printed by dispense printing using the poly[Ni-tto]-composite paste as n-type material and a commercial PEDOT-PSS paste as p-type material. A temperature gradient of 100 K produces a power output of about 20 nW. Full article
(This article belongs to the Special Issue Thin Films for Thermoelectric Applications)
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10 pages, 1372 KiB  
Article
First-Principles Study of Gas Molecule Adsorption on C-doped Zigzag Phosphorene Nanoribbons
by Shuai Yang, Zhiyong Wang, Xueqiong Dai, Jianrong Xiao, Mengqiu Long and Tong Chen
Coatings 2019, 9(11), 763; https://doi.org/10.3390/coatings9110763 - 18 Nov 2019
Cited by 12 | Viewed by 2547
Abstract
Phosphorene, due to its large surface-to-volume ratio and high chemical activity, shows potential application for gas sensing. In order to explore its sensing performance, we have performed the first-principles calculations based on density functional theory (DFT) to investigate the perfect and C-doped zigzag [...] Read more.
Phosphorene, due to its large surface-to-volume ratio and high chemical activity, shows potential application for gas sensing. In order to explore its sensing performance, we have performed the first-principles calculations based on density functional theory (DFT) to investigate the perfect and C-doped zigzag phosphorene nanoribbons (C-ZPNRs) with a series of small gas molecules (NH3, NO, NO2, H2, O2, CO, and CO2) adsorbed. The calculated results show that NH3, CO2, O2 gas molecules have relatively larger adsorption energies than other gas molecules, indicating that phosphorene is more sensitive to these gas molecules. For C-ZPNRs configuration, the adsorption energy of NO and NO2 increase and that of other gas molecules decrease. Interestingly, the adsorption energy of hydrogen is −0.229 eV, which may be suitable for hydrogen storage. It is hoped that ZPNRs may be a good sensor for (NH3, CO2 and O2) and C-ZPNRs may be useful for H2 storage. Full article
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10 pages, 2375 KiB  
Article
UV/Ozone-Assisted Rapid Formation of High-Quality Tribological Self-Assembled Monolayer
by Zhitao Fan, Chao Zhi, Lei Wu, Pei Zhang, Chengqiang Feng, Liang Deng, Bingjun Yu and Linmao Qian
Coatings 2019, 9(11), 762; https://doi.org/10.3390/coatings9110762 - 18 Nov 2019
Cited by 11 | Viewed by 5673
Abstract
UV/ozone (UVO)-assisted formation of self-assembled monolayer (SAM) of 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDS) was prepared on a glass surface. The effect of UVO exposure time on surface roughness and hydrophilicity was investigated through goniometer and atomic force microscope (AFM), and deposition time-dependent SAM quality was detected [...] Read more.
UV/ozone (UVO)-assisted formation of self-assembled monolayer (SAM) of 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDS) was prepared on a glass surface. The effect of UVO exposure time on surface roughness and hydrophilicity was investigated through goniometer and atomic force microscope (AFM), and deposition time-dependent SAM quality was detected by AFM and X-ray photoelectron spectroscopy (XPS). The glass surface became smooth with UVO radiation after 10 min, and the hydrophilicity was also improved after the treatment. Confirmed by surface topography detection and chemical composition analysis, a high-quality SAM can be formed rapidly on glass with 10 min UVO treatment followed by 2 h deposition in PFDS solution. Excellent tribological performances of SAM coated with UVO treatment glass were demonstrated by friction and wear tests on AFM compared to film-deposited glass without UVO treatment and original glass. The study sheds a light on preparing high-quality lubrication and antiwear self-assembled films on the surface of engineering materials. Full article
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19 pages, 40195 KiB  
Article
Evaluation of the Factors Affecting the Wear Resistance of Calcined Bauxite Aggregates
by Xirong Wu, Nanxiang Zhen and Fansheng Kong
Coatings 2019, 9(11), 761; https://doi.org/10.3390/coatings9110761 - 15 Nov 2019
Cited by 5 | Viewed by 2288
Abstract
The continuous use of load-bearing road surfaces often results in degradation over time, particularly if they are constructed from cement or aggregates that were poorly polished. Surfaces prepared from calcined bauxite exhibit good skid resistance properties, and this work describes a comparison of [...] Read more.
The continuous use of load-bearing road surfaces often results in degradation over time, particularly if they are constructed from cement or aggregates that were poorly polished. Surfaces prepared from calcined bauxite exhibit good skid resistance properties, and this work describes a comparison of the wear resistance of six different kinds of calcined bauxite with the aim of identifying the best material for road construction. Our results suggest that wear resistance of calcined bauxite is not only related to its hardness, but also dependent on the hardness dispersion throughout the aggregate and its elastic modulus. These data provide important information to enable the correct grade of bauxite clinker to be chosen for constructing high-friction road surfaces with good wear and skid resistance properties. Full article
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16 pages, 4348 KiB  
Article
An Investigation of the Polishing Behavior of Calcined Bauxite Aggregate
by Fa Yang, Bowen Guan, Jingyi Liu, Jiayu Wu, Jianan Liu, Chao Xie and Rui Xiong
Coatings 2019, 9(11), 760; https://doi.org/10.3390/coatings9110760 - 15 Nov 2019
Cited by 7 | Viewed by 2791
Abstract
The application of top-grade calcined bauxite to improve the skid resistance of pavement surface coatings increases construction costs and causes excessive tire wear. Therefore, it is necessary to investigate the polishing behavior of different grades of calcined bauxite aggregate. The polished stone value [...] Read more.
The application of top-grade calcined bauxite to improve the skid resistance of pavement surface coatings increases construction costs and causes excessive tire wear. Therefore, it is necessary to investigate the polishing behavior of different grades of calcined bauxite aggregate. The polished stone value of calcined bauxite was measured after the standard polishing time and the extended polishing time. The Los Angeles (L.A.) abrasion and the crushing value, profile roughness, hardness, X-ray diffraction, and micromorphology were also tested. The results showed that the calcined bauxite above 75# (the ratio of corundum to mullite by weight, C/M > 1) satisfied the requirement of the ultra-thin friction course. Compared with basalt, the calcined bauxite above 80# (C/M > 3) has better long-term skid resistance, even though the pavement surface is subject to heavier traffic. Due to the higher cohesion of lower porosity, more hard minerals to keep the surface roughness, and less soft minerals to smooth the surface roughness, calcined bauxite with a higher corundum content has the better skid resistance. There is a power law relationship between C/M and Polished Stone Value (PSV). Considering the diminishing returns of higher-grade calcined bauxite, it is necessary to accurately select the appropriate C/M of calcined bauxite before use in pavement surface coatings. Full article
(This article belongs to the Collection Pavement Surface Coatings)
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16 pages, 5802 KiB  
Article
Mechanical Properties of Strontium–Hardystonite–Gahnite Coating Formed by Atmospheric Plasma Spray
by Duy Quang Pham, Christopher C. Berndt, Ameneh Sadeghpour, Hala Zreiqat, Peng-Yuan Wang and Andrew S. M. Ang
Coatings 2019, 9(11), 759; https://doi.org/10.3390/coatings9110759 - 15 Nov 2019
Cited by 10 | Viewed by 3556
Abstract
In this work, we measured the mechanical properties and tested the cell viability of a bioceramic coating, strontium–hardystonite–gahnite (Sr–HT–G, Sr–Ca2ZnSi2O7–ZnAl2O4), to evaluate potential use of this novel bioceramic for bone regeneration applications. The [...] Read more.
In this work, we measured the mechanical properties and tested the cell viability of a bioceramic coating, strontium–hardystonite–gahnite (Sr–HT–G, Sr–Ca2ZnSi2O7–ZnAl2O4), to evaluate potential use of this novel bioceramic for bone regeneration applications. The evaluation of Sr–HT–G coatings deposited via atmospheric plasma spray (APS) onto Ti–6Al–4V substrates have been contrasted to the properties of the well-known commercial standard coating of hydroxyapatite (HAp: Ca10(PO4)6(OH)2). The Sr–HT–G coating exhibited uniform distribution of hardness and elastic moduli across its cross-section; whereas the HAp coating presented large statistical variations of these distributions. The Sr–HT–G coating also revealed higher results of microhardness, nanohardness and elastic moduli than those shown for the HAp coating. The nanoscratch tests for the Sr–HT–G coating presented a low volume of material removal without high plastic deformation, while the HAp coating revealed ploughing behaviour with a large pileup of materials and plastic deformation along the scratch direction. Furthermore, nanoscanning wear tests indicated that Sr–HT–G had a lower wear volume than the HAp coating. The Sr–HT–G coating had slightly higher cell attachment density and spreading area compared to the HAp coating indicating that both coatings have good biocompatibility for bone marrow mesenchymal stem cells (BMSCs). Full article
(This article belongs to the Special Issue Biointerface Coatings for Biomaterials and Biomedical Applications)
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12 pages, 2314 KiB  
Article
Effect of Graphene Oxide Concentration in Electrolyte on Corrosion Behavior of Electrodeposited Zn–Electrochemical Reduction Graphene Composite Coatings
by Bin Yang, Pengfei Zhang, Guangxin Wang, Aiqin Wang, Xiaofang Chen, Shizhong Wei and Jingpei Xie
Coatings 2019, 9(11), 758; https://doi.org/10.3390/coatings9110758 - 14 Nov 2019
Cited by 12 | Viewed by 2965
Abstract
Pure Zn and Zn–ERGO composite coatings were prepared by direct current electrodeposition on 304 stainless steel. Samples were characterized by X-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDS), and laser Raman spectroscopy (Raman). Results obtained have shown that [...] Read more.
Pure Zn and Zn–ERGO composite coatings were prepared by direct current electrodeposition on 304 stainless steel. Samples were characterized by X-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDS), and laser Raman spectroscopy (Raman). Results obtained have shown that the concentration of GO sheets in zinc sulfate electrolyte has an important effect on the preferred crystal orientation and the surface morphology of Zn–ERGO composite coatings. A study of the corrosion behavior of the coatings by Tafel polarization and electrochemical impedance spectroscopic (EIS) methods leads to the conclusion that the Zn-1.0 g/L ERGO composite coating possesses the best corrosion resistance compared to the pure Zn coating and other composite coatings in this study. Full article
(This article belongs to the Section Corrosion, Wear and Erosion)
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15 pages, 6596 KiB  
Article
Early-Age Tensile Bond Characteristics of Epoxy Coatings for Underwater Applications
by Sungwon Kim, Hyemin Hong, Taek Hee Han and Min Ook Kim
Coatings 2019, 9(11), 757; https://doi.org/10.3390/coatings9110757 - 14 Nov 2019
Cited by 10 | Viewed by 3543
Abstract
In this study, coating equipment for the effective underwater repair of submerged structures was developed. The tensile bond characteristics of selected epoxy resin coatings were investigated by coating the surface of a specimen using each of the four types of equipment. Using the [...] Read more.
In this study, coating equipment for the effective underwater repair of submerged structures was developed. The tensile bond characteristics of selected epoxy resin coatings were investigated by coating the surface of a specimen using each of the four types of equipment. Using the experimental results, the tensile bond strength and the coating thickness were analyzed according to the type of equipment, coating, and curing time. The results show that the type of coating equipment used had the greatest effect on the measured bond strength and coating thickness of the selected coatings. However, the effect of coating type and curing time on the bond strength and the thickness was observed to be insignificant. Compared with the developed equipment, the surface treatment of the coating was observed to be more effective when using the pre-existing equipment, and thus the bond performance of the coating was improved compared to using the pre-existing equipment. Based on the experimental results, improvements and needs involving the equipment for further research were discussed. Full article
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21 pages, 6597 KiB  
Article
A Stochastic Model and Investigation into the Probability Distribution of the Thickness of Boride Layers Formed on Low-Carbon Steel
by Julio C. Velázquez-Altamirano, Itzel P. Torres-Avila, Gerardo Teran-Méndez, Selene I. Capula-Colindres, Roman Cabrera-Sierra, Rafael Carrera-Espinoza and Enrique Hernández-Sánchez
Coatings 2019, 9(11), 756; https://doi.org/10.3390/coatings9110756 - 14 Nov 2019
Cited by 9 | Viewed by 2796
Abstract
The stochastic nature of the thickness of boride layers formed on carbon steel is described in this paper. Additionally, the probability distribution of the layer thickness is studied to determine the best-fit probability distribution. The study combines the use of an empirical model [...] Read more.
The stochastic nature of the thickness of boride layers formed on carbon steel is described in this paper. Additionally, the probability distribution of the layer thickness is studied to determine the best-fit probability distribution. The study combines the use of an empirical model (power-law) and the Markov chain principles, with the purpose of demonstrating that it is feasible to develop a model that represents the non-uniformity of the thickness of boride layers that form on carbon steel. The results indicate that the mean and variance tend to increase when the time or temperature is increased. The findings of this paper demonstrate that an analytical solution to the Kolmogorov’s system differential equation can adequately represent the behavior of non-uniform boride layer formed on low-carbon steel, regardless of the temperature or duration of treatment. Full article
(This article belongs to the Section Surface Characterization, Deposition and Modification)
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12 pages, 4467 KiB  
Article
Characterization of Ceramics Coatings Processed by Sol-Gel for Cutting Tools
by Bruna Aparecida Rezende, Anderson Júnior dos Santos, Marcelo Araújo Câmara, Denilson José do Carmo, Manuel Houmard, Alessandro Roger Rodrigues and Juan Carlos Campos Rubio
Coatings 2019, 9(11), 755; https://doi.org/10.3390/coatings9110755 - 14 Nov 2019
Cited by 12 | Viewed by 3102
Abstract
In order to obtain better cutting tool performance, the coatings appear as an alternative in the machining process. The goal of the coating is to improve tribological conditions in the chip-tool and tool-workpiece interfaces. On the other hand, the use of coated tools [...] Read more.
In order to obtain better cutting tool performance, the coatings appear as an alternative in the machining process. The goal of the coating is to improve tribological conditions in the chip-tool and tool-workpiece interfaces. On the other hand, the use of coated tools decreases the wear of the tools. This study discusses the ceramic coatings characterization deposited in WC tools. The Al2O3 and TiO2 films present properties such as thermal stability, chemical inertia, high hardness, and good mechanical properties. These coatings were prepared by sol-gel technology. The results indicated that the multilayer coating presents better adhesion on the substrate. Moreover, lower coefficients of friction were found for the coated tools. The analysis of variance (ANOVA) was used to evaluate the influence of the cutting parameters and tool coating on the cutting force. The lower cutting force was obtained using the multilayer-coated tool. Thus, the sol-gel method appears as a novel technique to deposit coating in the WC tools to improve their performance. Full article
(This article belongs to the Special Issue Coatings for Cutting and Stamping Tools: Recent Advances)
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8 pages, 3570 KiB  
Article
Surface Modification of Graphene for Use as a Structural Fortifier in Water-Borne Epoxy Coatings
by Ya Liu, Chao Xia, Abdelhafid Zehri, Lilei Ye, Nan Wang, Boris Zhmud, Hongbin Lu and Johan Liu
Coatings 2019, 9(11), 754; https://doi.org/10.3390/coatings9110754 - 13 Nov 2019
Cited by 13 | Viewed by 2887
Abstract
Graphene, the typical two-dimensional sp2 hybridized carbon allotrope, is widely used as a filler for improving the mechanical performance of polymers. However, its superhydrophobic surface makes it a big challenge to obtain stable graphene dispersions, especially in water-borne systems. On the contrary, [...] Read more.
Graphene, the typical two-dimensional sp2 hybridized carbon allotrope, is widely used as a filler for improving the mechanical performance of polymers. However, its superhydrophobic surface makes it a big challenge to obtain stable graphene dispersions, especially in water-borne systems. On the contrary, graphene oxide (GO) shows excellent dispersibility in water, but strong oxidants and acids destroy its structure and degrade its mechanical properties. This largely limits its application in water-borne coatings. In this work, graphene from mechanical exfoliation was surface modified by p-aminophenol derived diazonium salt to achieve a homogenous dispersion. Moreover, the hydroxyl groups in p-aminophenol are able to combine with epoxy resins during the curing process to improve mechanical performance of the final coatings. The result shows that functionalized graphene shows a lower coefficient of friction and better abrasion resistance compared to GO. Full article
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26 pages, 6210 KiB  
Review
Superhydrophobic Civil Engineering Materials: A Review from Recent Developments
by Tengfei Xiang, Zhong Lv, Feifei Wei, Jian Liu, Wei Dong, Cheng Li, Yingxuan Zhao and Depeng Chen
Coatings 2019, 9(11), 753; https://doi.org/10.3390/coatings9110753 - 13 Nov 2019
Cited by 35 | Viewed by 7833
Abstract
Superhydrophobic surfaces have drawn attention from scientists and engineers because of their extreme water repellency. More interestingly, these surfaces have also demonstrated an infinite influence on civil engineering materials. In this feature article, the history of wettability theory is described firstly. The approaches [...] Read more.
Superhydrophobic surfaces have drawn attention from scientists and engineers because of their extreme water repellency. More interestingly, these surfaces have also demonstrated an infinite influence on civil engineering materials. In this feature article, the history of wettability theory is described firstly. The approaches to construct hierarchical micro/nanostructures such as chemical vapor deposition (CVD), electrochemical, etching, and flame synthesis methods are introduced. Then, the advantages and limitations of each method are discussed. Furthermore, the recent progress of superhydrophobicity applied on civil engineering materials and its applications are summarized. Finally, the obstacles and prospects of superhydrophobic civil engineering materials are stated and expected. This review should be of interest to scientists and civil engineers who are interested in superhydrophobic surfaces and novel civil engineering materials. Full article
(This article belongs to the Special Issue Low-Adhesion Coatings: Fundamentals and Applications)
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11 pages, 2493 KiB  
Article
Rolling Contact Performance of a Ti-Containing MoS2 Coating Operating Under Ambient, Vacuum, and Oil-Lubricated Conditions
by Harpal Singh, Kalyan C. Mutyala and Gary L. Doll
Coatings 2019, 9(11), 752; https://doi.org/10.3390/coatings9110752 - 13 Nov 2019
Cited by 10 | Viewed by 3027
Abstract
Solid lubricant molybdenum disulfide (MoS2) coatings have been frequently used to lubricate mechanisms operating in environments where oil and grease lubrication are ineffective. This work evaluated the rolling contact performance of a Titanium-containing MoS2 coating under humid ambient, vacuum, and [...] Read more.
Solid lubricant molybdenum disulfide (MoS2) coatings have been frequently used to lubricate mechanisms operating in environments where oil and grease lubrication are ineffective. This work evaluated the rolling contact performance of a Titanium-containing MoS2 coating under humid ambient, vacuum, and oil-lubricated conditions. Weibull analyses of L50 lifetimes of AISI 52100 steel balls coated with a Ti-MoS2 coating paired with uncoated M50 steel rods were determined to be 3.7, 14.5, and 158.6 million cycles in ambient, vacuum, and oil-lubricated environments, respectively. In the ambient and vacuum tests, failures were determined to be associated with the onset of abrasive wear rather than fatigue or spalling. The L50 lifetimes of tests performed in those environments were found to depend upon the wear rate of the coatings on the balls. That is, the Ti-MoS2 functioned as a barrier to the onset of abrasive wear between the steel alloys until the coating was sufficiently worn away. Under oil-lubricated (boundary lubrication) conditions, L50 was found to depend on the durability and composition of tribofilms formed in-situ on the surfaces of the uncoated M50 rods. The tribofilms were comprised of mixtures of MoS2 crystallites and amorphous hydrocarbon (a-C:H). The crystalline MoS2 in the tribofilm originated from the amorphous Ti-MoS2 coating and likely underwent a thermodynamic phase transition as a result of the applied Hertz stress and frictional heating in the contact. The a-C:H in the tribofilm probably originated from a catalytic scission of the polyalphaolefin (PAO) molecules caused by the d-band character of the Mo or Ti in the coating. Overall, the Ti-MoS2-coated balls were effective at extending the operational lifetimes of M50 rods under ambient, vacuum, and oil-lubricated conditions by an order of magnitude. Full article
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15 pages, 12609 KiB  
Article
Luminescence of CsI and CsI:Na Films under LED and X-ray Excitation
by Jin-Cherng Hsu and Yu-Shen Ma
Coatings 2019, 9(11), 751; https://doi.org/10.3390/coatings9110751 - 13 Nov 2019
Cited by 8 | Viewed by 4517
Abstract
In this study, we investigated the luminous properties of undoped cesium iodide (CsI) and Na-doped CsI (CsI:Na) films deposited by thermal vacuum evaporation and treated with different substrate temperatures, post-annealing temperatures, and deposition rates. The quality of the deposited films was evaluated by [...] Read more.
In this study, we investigated the luminous properties of undoped cesium iodide (CsI) and Na-doped CsI (CsI:Na) films deposited by thermal vacuum evaporation and treated with different substrate temperatures, post-annealing temperatures, and deposition rates. The quality of the deposited films was evaluated by their XRD pattern, SEM cross-section/surface morphologies and UV/X-ray luminescence, the spectra of which were used to derive the luminescence mechanism of the deposited films. The 310 nm luminescence demonstrates that the exciting light arises from the electron–hole recombination through the self-trapped exciton (STE) process, which is characteristic of the host polycrystalline CsI. The broad-band luminescence from ~400 to 450 nm demonstrates the other electron–hole recombination between the new energy states created by doping Na in the forbidden gap of CsI. When we deposited higher quality films at a substrate temperature of 200 °C, the undoped CsI films showed preferred crystal orientation at (200), and the CsI:Na films co-evaporated by 1 wt.% NaI at (310) and had the highest UV/X-ray luminescence. Full article
(This article belongs to the Special Issue Functional Thin Films: Design, Fabrication and Applications)
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14 pages, 5351 KiB  
Article
Electrodeposition of a Ni–P–TiO2/Ti3C2Tx Coating with In Situ Grown Nanoparticles TiO2 on Ti3C2Tx Sheets
by Yingchao Du, Xiaomeng Zhang, Lianqi Wei, Bo Yu, Daqing Ma and Shufeng Ye
Coatings 2019, 9(11), 750; https://doi.org/10.3390/coatings9110750 - 12 Nov 2019
Cited by 15 | Viewed by 3215
Abstract
Protective coatings have received considerable attention for the surface treatment of devices. Herein, in situ grown nanoparticles, TiO2 on Ti3C2Tx sheets (TiO2/Ti3C2Tx), are prepared by a simple hydrothermal oxidation [...] Read more.
Protective coatings have received considerable attention for the surface treatment of devices. Herein, in situ grown nanoparticles, TiO2 on Ti3C2Tx sheets (TiO2/Ti3C2Tx), are prepared by a simple hydrothermal oxidation method possessing the layer structure, which is applied to prepare protective coatings. The Ni–P–TiO2/Ti3C2Tx coating is prepared by electroplating technology, revealing more excellent properties than those of the Ni–P coating. Compared with the Ni–P coating, even though the Ni–P–TiO2/Ti3C2Tx coating holds the rough surface, the wettability is changed from hydrophilic to hydrophobic, owing to the gathering existence of TiO2/Ti3C2Tx on the surface and coarse surface texture. In addition, the participation of TiO2/Ti3C2Tx in the Ni–P coating can improve the capacity of corrosion prevention and decrease the corrosion rate. According to the results of hardness and wear tests, microhardness of the Ni–P–TiO2/Ti3C2Tx coating is approximately 1350 kg mm−2 and the coefficient of friction (COF) of Ni–P–TiO2/Ti3C2Tx coatings is about 0.40, which is much lower than that of Ni–P coatings. Thus, the Ni–P–TiO2/Ti3C2Tx coating can be a promising material to protect the surface of equipment. Full article
(This article belongs to the Section Corrosion, Wear and Erosion)
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19 pages, 5010 KiB  
Article
Advanced Analysis of Corroded Solar Reflectors
by Francisco Buendía-Martínez, Aránzazu Fernández-García, Florian Sutter, Loreto Valenzuela and Alejandro García-Segura
Coatings 2019, 9(11), 749; https://doi.org/10.3390/coatings9110749 - 11 Nov 2019
Cited by 4 | Viewed by 2503
Abstract
The corrosion of the reflective layer is one of the main degradation mechanisms of solar reflectors. However, the appropriate assessment of the corroded reflector samples is not accomplished by the current analysis techniques. On the one hand, the reflectance measurement protocol of non-damaged [...] Read more.
The corrosion of the reflective layer is one of the main degradation mechanisms of solar reflectors. However, the appropriate assessment of the corroded reflector samples is not accomplished by the current analysis techniques. On the one hand, the reflectance measurement protocol of non-damaged solar reflectors for concentrating solar thermal technologies is widely addressed in the SolarPACES reflectance guideline. However, this methodology is not adequate for reflectors whose surface is partially corroded by many kind of corrosion agents. In this work, a new measurement technique to properly assess corroded samples was developed. To check the usefulness of the method, several damaged samples (subjected to two accelerated aging tests) were evaluated with the conventional technique and with the improved one. The results showed that a significant discrepancy is observed between the two methods for heavily corroded samples, with average reflectance differences of 0.053 ppt. The visualization of the reflector images illustrated that the improved method is more reliable. On the other hand, both the corrosion products formed and the corrosion rates were identified after each corrosive test. The chemical atmosphere significantly affects the products formed, whereas the corrosion rates are influenced by the test conditions and the reflector quality. Full article
(This article belongs to the Special Issue Surfaces and Interfaces for Renewable Energy)
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18 pages, 21009 KiB  
Article
Synthesis and Characterization of Nanostructured Polyaniline Thin Films with Superhydrophobic Properties
by Zeinab Abdel Hamid, Mona Hasan Gomaa, Sayed S. Abdel Rehim, Maamoun Abdel Hamid and Ahmed Ibrahim
Coatings 2019, 9(11), 748; https://doi.org/10.3390/coatings9110748 - 11 Nov 2019
Cited by 21 | Viewed by 4144
Abstract
Polyaniline (PANI) thin films incorporated with TiO2 or ZnO nanoparticles were synthesized via an electrochemical polymerization technique. Cyclic voltammetry (CV) was used to synthesize PANI from a strongly acidic medium (0.5 M H2SO4). The effects of different deposition [...] Read more.
Polyaniline (PANI) thin films incorporated with TiO2 or ZnO nanoparticles were synthesized via an electrochemical polymerization technique. Cyclic voltammetry (CV) was used to synthesize PANI from a strongly acidic medium (0.5 M H2SO4). The effects of different deposition cycles on the morphology, thickness, color, and properties of electrodeposited PANI thin films nanocomposites were investigated. Furthermore, the effects of the nanoparticles concentration on the morphology and water contact angle (CA) of the produced coating were investigated. Field-emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) were used to investigate the morphological structure. X-ray photoelectron spectroscopy (XPS) was used to study the surface composition of the formed film. The results reveal that the CA of the prepared coating reached 146°. A granular morphology of PANI with a moderate concentration of nanoparticles was obtained. In addition, XPS analysis confirmed the incorporation of the oxide nanoparticles in the matrix. Full article
(This article belongs to the Special Issue Thin-Film Synthesis, Characterization and Properties)
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9 pages, 3665 KiB  
Article
Tribological Performance of a Ni-Based Composite Coating in Artificial Seawater
by Bo Li, Cong Li, Yimin Gao, Hongjian Guo, Yunchuan Kang and Siyong Zhao
Coatings 2019, 9(11), 747; https://doi.org/10.3390/coatings9110747 - 11 Nov 2019
Cited by 2 | Viewed by 2188
Abstract
NiCrAlY and NiCrAlY-Mo coatings were fabricated by atmospheric plasma spraying (APS). The corrosion-wear performance of the coatings was investigated in artificial seawater and the synergistic mechanism between wear and corrosion were evaluated in detail. Results showed that the diffraction peaks of Ni3 [...] Read more.
NiCrAlY and NiCrAlY-Mo coatings were fabricated by atmospheric plasma spraying (APS). The corrosion-wear performance of the coatings was investigated in artificial seawater and the synergistic mechanism between wear and corrosion were evaluated in detail. Results showed that the diffraction peaks of Ni3Al shifted to the right and the microhardness of the coating was improved from 329.8 HV to 342.5 HV with adding the Mo element. Meanwhile, the NiCrAlY-Mo coating had a lower friction coefficient, with a wear rate of 0.26 and 3.69 × 10−6 mm3/Nm, compared to the NiCrAlY coating with a wear rate of 0.37 and 4.67 × 10−6 mm3/Nm. The NiCrAlY coating had severe corrosion and the corrosion mainly occurred in grain boundary. Adding the Mo element, the Mo element was distributed in the grain boundary and the coating had a lower corrosion rate and visibly slighter corrosion. The NiCrAlY-Mo coating had excellent corrosion-wear properties in artificial seawater. Full article
(This article belongs to the Section Corrosion, Wear and Erosion)
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18 pages, 13832 KiB  
Article
Influence of Substrate Shape and Roughness on Coating Microstructure in Suspension Plasma Spray
by Fernanda Caio and Christian Moreau
Coatings 2019, 9(11), 746; https://doi.org/10.3390/coatings9110746 - 11 Nov 2019
Cited by 12 | Viewed by 4063
Abstract
This study investigated the influence of the substrate shape and roughness on the microstructure of suspension plasma spray (SPS) coatings. For this purpose, an yttria-stabilized zirconia (YSZ) suspension was sprayed on flat and curved stainless-steel substrates by SPS. The suspension was composed of [...] Read more.
This study investigated the influence of the substrate shape and roughness on the microstructure of suspension plasma spray (SPS) coatings. For this purpose, an yttria-stabilized zirconia (YSZ) suspension was sprayed on flat and curved stainless-steel substrates by SPS. The suspension was composed of 20 wt.% YSZ particles in ethanol. After spraying, the morphology of the coatings was characterized by scanning electron microscopy (SEM). The results showed that the substrate shape influences the amount of coating material deposited and microstructural features of the coating. The amount of coating material deposited was seen to decrease as the radius of curvature decreased. Finally, the roughness was found to influence the formation of columnar structure. Full article
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10 pages, 727 KiB  
Article
Application of Pullulan and Chitosan Multilayer Coatings in Fresh Papayas
by Linyun Zhang, Chongxing Huang and Hui Zhao
Coatings 2019, 9(11), 745; https://doi.org/10.3390/coatings9110745 - 10 Nov 2019
Cited by 29 | Viewed by 3567
Abstract
In this work, some multilayer coatings (two-layer, four-layer or six-layer) based on pullulan and chitosan for protecting papayas were prepared by the layer-by-layer technique. The papayas were coated by immersion and stored at 25 °C, 50% relative humidity or up to 14 days. [...] Read more.
In this work, some multilayer coatings (two-layer, four-layer or six-layer) based on pullulan and chitosan for protecting papayas were prepared by the layer-by-layer technique. The papayas were coated by immersion and stored at 25 °C, 50% relative humidity or up to 14 days. Uncoated and monolayer-coated papayas were used as controls. The pullulan/chitosan coatings decreased the papaya weight loss, softening, color change (b*, ΔE), and pH, retarded the fall of titratable acidity and vitamin C, and maintained respiratory rate and soluble solid contents. Sensory quality evaluation demonstrated that pullulan/chitosan coatings effectively preserved papaya flavor and overall acceptance. In general, the four-layer coatings provided the best fruit preservation. In conclusion, multilayer pullulan/chitosan coatings are efficient in maintaining the post-harvest quality and prolonging the shelf life of fresh papaya. Full article
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13 pages, 4361 KiB  
Article
One-Step Preparation of Nickel Nanoparticle-Based Magnetic Poly(Vinyl Alcohol) Gels
by Jun Li, Kwang-Pill Lee and Anantha Iyengar Gopalan
Coatings 2019, 9(11), 744; https://doi.org/10.3390/coatings9110744 - 9 Nov 2019
Cited by 8 | Viewed by 3148
Abstract
Magnetic nanoparticles (MNPs) are of great interest due to their unique properties, especially in biomedical applications. MNPs can be incorporated into other matrixes to prepare new functional nanomaterials. In this work, we described a facile, one-step strategy for the synthesis of magnetic poly(vinyl [...] Read more.
Magnetic nanoparticles (MNPs) are of great interest due to their unique properties, especially in biomedical applications. MNPs can be incorporated into other matrixes to prepare new functional nanomaterials. In this work, we described a facile, one-step strategy for the synthesis of magnetic poly(vinyl alcohol) (mPVA) gels. In the synthesis, nickel nanoparticles and cross-linked mPVA gels were simultaneously formed. Ni nanoparticles (NPs) were also incorporated into a stimuli-responsive polymer to result in multiresponsive gels. The size of and distribution of the Ni particles within the mPVA gels were controlled by experimental conditions. The mPVA gels were characterized by field emission scanning electron microscope, X-ray diffraction, magnetic measurements, and thermogravimetric analysis. The new mPVA gels are expected to have applications in drug delivery and biotechnology. Full article
(This article belongs to the Special Issue Biointerface Coatings for Biomaterials and Biomedical Applications)
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8 pages, 4047 KiB  
Article
Condensation Test and Simulation of Superhydrophobic Coatings
by Yunhua He, Yuling Yang, Xinliang Guo and Huanhuan Xia
Coatings 2019, 9(11), 743; https://doi.org/10.3390/coatings9110743 - 8 Nov 2019
Cited by 6 | Viewed by 2529
Abstract
Pollution flashover accidents pose a great threat to the safe and stable operation of a power system, and superhydrophobic materials have broad application prospects in the field of pollution flashover prevention of the external insulation of transmission and transformation equipment. In this paper, [...] Read more.
Pollution flashover accidents pose a great threat to the safe and stable operation of a power system, and superhydrophobic materials have broad application prospects in the field of pollution flashover prevention of the external insulation of transmission and transformation equipment. In this paper, PVDF@PMMA/SiO2 superhydrophobic coatings were prepared using a spraying method. Superhydrophobicity is defined as an angle larger than 150° and a small roll-off angle smaller than 10°. The static contact angle of the coatings reached 155°, which meant they had excellent superhydrophobic properties. The distribution characteristics of water droplets on superhydrophobic surface were analyzed through a live condensation test, and simulation analysis was carried out. It was found that the distance between water droplets on the superhydrophobic surface was larger, which increased the distance of the arc development; the static contact angle was larger; and the electric field strength at the three-phase junction was lower. Both of them worked together to enhance the pollution flashover voltage of the coating. Full article
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13 pages, 4603 KiB  
Article
Influence of Thermochromic Pigment Powder on Properties of Waterborne Primer Film for Chinese Fir
by Xiaoxing Yan, Lin Wang and Xingyu Qian
Coatings 2019, 9(11), 742; https://doi.org/10.3390/coatings9110742 - 8 Nov 2019
Cited by 17 | Viewed by 3303
Abstract
This study chose organic thermochromic pigment powder and waterborne wood primer as the paint base, and Chinese fir board as the substrate to prepare thermochromic waterborne coatings with different concentrations of thermochromic pigment powder. The best concentration of thermochromic pigment powder for waterborne [...] Read more.
This study chose organic thermochromic pigment powder and waterborne wood primer as the paint base, and Chinese fir board as the substrate to prepare thermochromic waterborne coatings with different concentrations of thermochromic pigment powder. The best concentration of thermochromic pigment powder for waterborne primer film on Chinese fir surface was explored. The experimental results showed that the color-changing property of the primer film was the best when the concentration of pigment powder in primer film was 5.0%–10%. There was a negative correlation between the gloss of the primer and the concentration of pigment powder. The gloss of the primer film was the highest when the concentration of pigment powder was 5%. When the concentration of pigment powder is 0%–20% and 25.0%–30%, the adhesion of the coating is grade 0 and grade 1, respectively. The resistance to the impact of primer film increased with the increase of concentration of pigment powder, but the resistance to the impact of primer film with 0%–30% of thermochromic pigment powder concentration was similar. Scanning electron microscopy showed that the higher the concentration of thermochromic pigment powder, the more particles and agglomeration. When the concentration of pigment powder was 5%, the distribution of particles was uniform and no agglomeration, and the microstructure of primer film was the best. Infrared spectroscopy showed that there was no difference in the composition of the paint film from 0% to 30%. The results showed that the comprehensive property of waterborne primer film on Chinese fir was better when the pigment concentration was 5%. Waterborne thermochromic primer film provides a potential application for the development of intelligent furniture in different temperature ranges. Full article
(This article belongs to the Special Issue Paints and Paint Additives)
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15 pages, 2168 KiB  
Article
Analysis of a Thin Layer Formation of Third-Grade Fluid
by Tareq Manzoor, Kashif Nazar, Muhammad Zafar, Shaukat Iqbal, Muddassir Ali, Woo Young Kim, Mahmood Saleem and Sanaullah Manzoor
Coatings 2019, 9(11), 741; https://doi.org/10.3390/coatings9110741 - 8 Nov 2019
Cited by 5 | Viewed by 2061
Abstract
In present learning, surface protection layer progression of a third-grade fluid (TGF) is examined. Fluid transport within the micro passage made by the firm bladehas beenpresented. Main system of equations of fluidity have been narrated and streamlined by means of lubrication approximation theory [...] Read more.
In present learning, surface protection layer progression of a third-grade fluid (TGF) is examined. Fluid transport within the micro passage made by the firm bladehas beenpresented. Main system of equations of fluidity have been narrated and streamlined by means of lubrication approximation theory (LAT). Here, approximate solutions of velocity, pressure gradient, and coating depth have been presented. Results of coating and layer forming have been tabulated and discussed as well. It is observed that the transport properties of third-order fluid delivers an instrument to regulate flow velocity, pressure, and affect the final coated region. Full article
(This article belongs to the Section Surface Characterization, Deposition and Modification)
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