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Coatings, Volume 12, Issue 2 (February 2022) – 185 articles

Cover Story (view full-size image): A widely used polymer, polyethylene terephthalate (PET), was used as a substrate for the preparation of surfaces with repellent properties. The necessary roughness for the appearance of hydrophobic properties was generated by a simple, fast, and cheap method that just involves immersion in a common solvent. After a final fluorination step, it is possible to obtain surfaces that present a contact angle higher than 150° and low adhesion of water droplets. The generation of roughness by induced crystallization has proven to be a very promising methodology that could be applied to other semi-crystalline polymers or copolymers to develop microstructured surfaces at a large scale. View this paper
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Article
Experimental Study of Irradiation of Thin Oxide and Mo/Si Multilayers by High Brightness Broadband VUV/UV Radiation and Their Degradation
Coatings 2022, 12(2), 290; https://doi.org/10.3390/coatings12020290 - 21 Feb 2022
Viewed by 470
Abstract
This study discusses the main features of the irradiation of prospective multilayer coatings by VUV/UV radiation from compressed plasma flows. Such radiation is characterized by a broadband spectrum and high brightness fluxes. Oxide and Mo/Si bilayers were used as the basis of the [...] Read more.
This study discusses the main features of the irradiation of prospective multilayer coatings by VUV/UV radiation from compressed plasma flows. Such radiation is characterized by a broadband spectrum and high brightness fluxes. Oxide and Mo/Si bilayers were used as the basis of the reflective multilayers for the visible and UV ranges. A gas-dynamic response from the irradiated surfaces was studied with schlieren photography. The properties of original and irradiated multilayers were described with ultra violet visible infrared spectroscopy (UV-Vis-IR), X-ray diffraction (XRD), X-ray reflectometry, scanning electron microscopy (SEM) and other techniques. Data on the degradation of optical properties and surface morphology were obtained. Full article
(This article belongs to the Special Issue Optical Thin Films: Preparation, Application and Development)
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Article
The LiTFSI/COFs Fiber as Separator Coating with Bifunction of Inhibition of Lithium Dendrite and Shuttle Effect for Li-SeS2 Battery
Coatings 2022, 12(2), 289; https://doi.org/10.3390/coatings12020289 - 21 Feb 2022
Cited by 1 | Viewed by 472
Abstract
The safety problem caused by lithium dendrite of lithium metal anode and the rapid capacity decay problem caused by the shuttle effect of polysulfide and polyselenide during the charge and discharge of selenium disulfide cathode limit the application of lithium selenium disulfide batteries [...] Read more.
The safety problem caused by lithium dendrite of lithium metal anode and the rapid capacity decay problem caused by the shuttle effect of polysulfide and polyselenide during the charge and discharge of selenium disulfide cathode limit the application of lithium selenium disulfide batteries significantly. Here, a fibrous ATFG-COF, containing rich carbonyl and amino functional groups, was applied as the separator coating layer. Density Functional Theory (DFT) theoretical calculations and experimental results showed that the abundant carbonyl group in ATFG-COF had a positive effect on lithium ions, and the amino group formed hydrogen bonds with bis ((trifluoromethyl) sulfonyl) azanide anionics (TFSI), which fixed TFSI in the channel, so as to improve the transfer number of lithium ions and narrow the channels. Therefore, ATFG-COF fiber coating can not only form a rapid and uniform lithium-ion flow on the lithium anode to inhibit the growth of lithium dendrites, but also effectively screen polysulfide and polyselenide ions to suppress the shuttle effect. The Li-SeS2 cell with ATFG-COF/polypropylene (ATFG-COF/PP) separator exhibited good cycle stability at 0.5 C and maintained a specific capacity of 509 mAh/g after 200 cycles. Our work provides insights into the design of dual-function separators with high-performance batteries. Full article
(This article belongs to the Special Issue Advanced Materials for Metal-Ion Batteries)
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Article
Simultaneous Precipitation and Electrodeposition of Hydroxyapatite Coatings at Different Temperatures on Various Metal Substrates
Coatings 2022, 12(2), 288; https://doi.org/10.3390/coatings12020288 - 21 Feb 2022
Cited by 1 | Viewed by 412
Abstract
The coating of orthopedic and dental implants with hydroxyapatite (HA) is recognized as a method to increase their integration ability. A new metal coating method, comprising simultaneous precipitation and electrodeposition, is presented. Two studies are described: the first is related to the influence [...] Read more.
The coating of orthopedic and dental implants with hydroxyapatite (HA) is recognized as a method to increase their integration ability. A new metal coating method, comprising simultaneous precipitation and electrodeposition, is presented. Two studies are described: the first is related to the influence of time/temperature increase on the morpho-structural characteristics of the deposited layer on the Ti substrate, while the second study presents the characteristics of the layers deposited on different metal substrates. For comparison, specimens were obtained using the classical electrochemical deposition under the same experimental conditions. The addition of Ca to the electrolyte creates more compact and more uniform coatings, while the addition of P creates more porous layers. Only a very small quantity of crystalline HA deposited on the C55, Cu, and Ni substrates when the classic electrodeposition method was employed, while using the new approach has clearly led to a larger crystalline HA amount electrodeposited on the same types of metals. With some exceptions, the advantages of using the new method are: better crystallinity, more uniform and continuous surface, higher roughness, and potentially higher anti-corrosion capabilities. Full article
(This article belongs to the Special Issue Development of Hydroxyapatite Coatings)
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Article
Low-Temperature Performance of Asphalt Mixtures Modified by Microencapsulated Phase Change Materials with Various Graphene Contents
Coatings 2022, 12(2), 287; https://doi.org/10.3390/coatings12020287 - 21 Feb 2022
Viewed by 453
Abstract
Microencapsulated phase change materials (PCMs) added to conventional ones can store excessive heat energy and reduce thermal stresses. In this study, melamine–formaldehyde resin phase change microencapsulated PCMs, with different contents of graphene (CG), were added to asphalt mixtures, in order to reduce their [...] Read more.
Microencapsulated phase change materials (PCMs) added to conventional ones can store excessive heat energy and reduce thermal stresses. In this study, melamine–formaldehyde resin phase change microencapsulated PCMs, with different contents of graphene (CG), were added to asphalt mixtures, in order to reduce their low-temperature cracking, induced by thermal stresses. Low-temperature and heat-conducting/storing performance of the obtained mixtures was examined via beam bending tests, semi-circular bending low-temperature performance tests, thermal conductivity tests and volume-specific heat capacity tests. Besides, the prepared asphalt mixtures’ water stability and high-temperature stability values were obtained via freeze-thaw splitting and wheel tracking tests. The low-temperature performance of PCM-modified asphalt mixtures was evaluated via their bending strain energy densities, with one of the PCM-modified asphalt mixtures, namely CGMFPCM3, synthesized by the authors, was 1.7 times higher than that of the common asphalt mixture. Although the dynamic stability of all three PCM-modified mixtures was deteriorated by 68, 50, and 20% compared to the common one, that of CGMFPCM3 still complied with the standard requirement. Thermal conductivity and volume-specific heat capacity of the asphalt mixture at 278.15 K was enhanced by 5 and 43%, respectively, after adding CGMFPCM3. It is recommended for reducing the temperature variation-induced cracking in the asphalt pavement. Thermal conductivity and volume-specific heat capacity can be used for evaluating the temperature-regulating performance of asphalt mixtures. Full article
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Article
Photocatalytic Treatment of Methyl Orange Dye Wastewater by Porous Floating Ceramsite Loaded with Cuprous Oxide
Coatings 2022, 12(2), 286; https://doi.org/10.3390/coatings12020286 - 21 Feb 2022
Viewed by 442
Abstract
It is well known that water treatment of printing and dyeing wastewaters is problematic. In order to decompose dyes from dyestuff wastewater and convert them into almost harmless substances for the natural environment, an easily prepared, efficient, practical, and easy-to-regenerate composite material was [...] Read more.
It is well known that water treatment of printing and dyeing wastewaters is problematic. In order to decompose dyes from dyestuff wastewater and convert them into almost harmless substances for the natural environment, an easily prepared, efficient, practical, and easy-to-regenerate composite material was produced from porous floating ceramsite loaded with cuprous oxide (PFCC). The PFCC samples were prepared and characterized by X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The material was applied for photocatalytic degradation of methyl orange (MO) in water. The results show that the maximal degradation rate of MO was 92.05% when the experimental conditions were as follows: cuprous oxide loading rate of 8%, PFCC dosage of 20 g/L, the reaction time of 2 h, pH value of 8, and solution initial concentration of 30 mg/L. The degradation processes of MO fits well with the Langmuir–Hinshelwood model in reaction kinetics, and the Freundlich model in reaction thermodynamics, respectively. The degradation mechanism of MO was considered from two perspectives—one was the synergetic effect of adsorption and photocatalytic oxidation, and the other was the strong oxidation of hydroxyl radicals produced by photocatalysts. Full article
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Article
Formation Mechanism and Weights Analysis of Residual Stress Holes in E690 High-Strength Steel by Laser Shock Peening
Coatings 2022, 12(2), 285; https://doi.org/10.3390/coatings12020285 - 21 Feb 2022
Cited by 1 | Viewed by 435
Abstract
To investigate the surface residual stress hole formation mechanism induced by laser shock peening (LSP) in an E690 high-strength steel sheet and to assign weights to the relevant causes; E690 steel samples were loaded using four laser beams with different power densities. The [...] Read more.
To investigate the surface residual stress hole formation mechanism induced by laser shock peening (LSP) in an E690 high-strength steel sheet and to assign weights to the relevant causes; E690 steel samples were loaded using four laser beams with different power densities. The dynamic strain in thin plate samples was measured using a polyvinylidene fluoride piezoelectric sensor during LSP and the residual stress distributions on thin- and thick-plate samples were studied using an X-ray stress analyzer. The residual stress distribution of the simulated laser shock E690 high-strength steel sheet was consistent with that of the measured residual stress field, and the propagation pattern induced by a pulsed laser shock wave obtained via simulation shows good consistency with the surface dynamic strain test results. A shock wave propagation model was established for E690 high-strength steel sheets. At laser power densities of 1.98 and 2.77 GW/cm2, the residual stress fields obtained through simulations and experiments show the residual stress hole phenomenon. The combined effect of the shock wave, which is reflected back and forth, and the rarefaction waves that converge toward the center produced the residual stress hole phenomenon, and shock wave reflection has a slightly greater impact than surface rarefaction wave convergence on the residual stress holes on the material’s surface. When the laser power density is 4.07 GW/cm2, the maximum residual principal stress is distributed uniformly. Full article
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Article
Impact of Remelting in the Microstructure and Corrosion Properties of the Ti6Al4V Fabricated by Selective Laser Melting
Coatings 2022, 12(2), 284; https://doi.org/10.3390/coatings12020284 - 21 Feb 2022
Viewed by 570
Abstract
The presence of defects like porosity and lack of fusion can negatively affect the properties of the materials manufactured by Selective Laser Melting (SLM). The optimization of the manufacturing conditions allows reducing the number of defects, but there is a limit for each [...] Read more.
The presence of defects like porosity and lack of fusion can negatively affect the properties of the materials manufactured by Selective Laser Melting (SLM). The optimization of the manufacturing conditions allows reducing the number of defects, but there is a limit for each manufacturing material and process. To expand the manufacturing envelope, a remelting after every layer of the SLM process has been used to manufacture Ti6Al4V alloy samples using an SLM with a CO2 laser. The effect of this processing method on the microstructure, defects, hardness, and, especially, the corrosion properties was studied. It was concluded that the laser remelting strategy causes an increment of the α and β phases from the dissolution of metastable α’. This technique also provokes a decrease in the number of defects and a reduction of the hardness, which are also reduced with lower scanning speeds. On the other hand, all the corrosion tests show that a low scanning speed and the laser remelting strategy improve the corrosion resistance of the Ti6Al4V alloy since parameters like the Open Circuit Potential (OCP) and the Polarization Resistance (Rp) are nobler and the mass gain is lower. Full article
(This article belongs to the Special Issue The Applications of Laser Processing and Additive Manufacturing)
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Article
Chemical Bath Deposited Orthorhombic SnS Films for Solar Cell Applications
Coatings 2022, 12(2), 283; https://doi.org/10.3390/coatings12020283 - 21 Feb 2022
Viewed by 403
Abstract
Tin sulfide (SnS) thin films were deposited by the chemical bath deposition technique. The used procedure allows us to obtain orthorhombic SnS in 3.5 h and achieve thicknesses of 390 nm. We study the influence of deposition times, percentage of Sn precursor, and [...] Read more.
Tin sulfide (SnS) thin films were deposited by the chemical bath deposition technique. The used procedure allows us to obtain orthorhombic SnS in 3.5 h and achieve thicknesses of 390 nm. We study the influence of deposition times, percentage of Sn precursor, and post-annealing on the structural and optical properties. The X-ray diffraction measurements of SnS films prepared at a deposition time of 3 h showed orthorhombic structure with characteristic peaks of SnS2. However, increasing the deposition time and the Sn precursor, the orthorhombic SnS phase in these samples becomes predominant. Thin-film morphologies and thicknesses were identified by scanning electron microscopy (SEM). An increase in bandgap from 1.41 eV to 1.56 eV was observed by increasing Sn precursor. The optical properties remain constant after air annealing of 285 °C. Low-temperature photoluminescence spectra show emission bands at 2.5 eV attributed to the presence of SO2. Other deep level transitions were observed at about 0.9 eV, probably due to oxygen. Full article
(This article belongs to the Special Issue Optical Thin Film and Solar Cells)
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Article
Nanomechanical and Electrochemical Properties of ZnO-Nanoparticle-Filled Epoxy Coatings
Coatings 2022, 12(2), 282; https://doi.org/10.3390/coatings12020282 - 21 Feb 2022
Cited by 1 | Viewed by 462
Abstract
This work focuses on the mechanical, nanomechanical, thermal, and electrochemical properties of epoxy coatings with various percentages of ZnO nanoparticles. The prepared coatings were analyzed after complete curing of 7 days. The dispersion of nanoparticles in the matrix was analyzed by Scanning Electron [...] Read more.
This work focuses on the mechanical, nanomechanical, thermal, and electrochemical properties of epoxy coatings with various percentages of ZnO nanoparticles. The prepared coatings were analyzed after complete curing of 7 days. The dispersion of nanoparticles in the matrix was analyzed by Scanning Electron Microscopy (SEM) followed by Fourier-Transformed Infrared Spectroscopy (FTIR) to evaluate the effect of the nanoparticles on curing and Differential Scanning Calorimetry (DSC) to evaluate its thermal properties. The electrochemical (anticorrosion) properties of the coatings were analyzed by exposing the prepared coatings to a 3.5% NaCl solution. The obtained results indicated that the addition of the nanoparticles was effective at lower loadings; higher loadings of the nanoparticles led to increased agglomeration because of higher particle–particle interaction. At higher nanoparticle loadings, the curing process was adversely affected, which led to lower curing percentage. The lower degree of curing affected the thermal, mechanical, and electrochemical properties. The increase in nanoparticle loading beyond 2% negatively affected the coating properties. Full article
(This article belongs to the Special Issue Advances in Corrosion Resistant Coatings)
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Article
Effect of Cryogenic Treatment on the Microstructure and Wear Resistance of 17Cr2Ni2MoVNb Carburizing Gear Steel
Coatings 2022, 12(2), 281; https://doi.org/10.3390/coatings12020281 - 21 Feb 2022
Viewed by 430
Abstract
Cryogenic treatment as a process that can effectively improve the performance of steel materials is widely used because of its simplicity and speed. This paper investigates the effects of different low temperature treatments on the microstructure and properties of 17Cr2Ni2MoVNb steel. The low [...] Read more.
Cryogenic treatment as a process that can effectively improve the performance of steel materials is widely used because of its simplicity and speed. This paper investigates the effects of different low temperature treatments on the microstructure and properties of 17Cr2Ni2MoVNb steel. The low temperature treatment range is divided into cryogenic treatment (CT-80), shallow cryogenic treatment (SCT-150) and deep cryogenic treatment (DCT-196), all with a duration of 1 h. The retained austenite content and the change in carbide volume fraction at 0.2 mm in the carburised layer are studied. The microhardness gradient of the carburised layer, as well as the friction coefficient and wear scar morphology at 0.2 mm, was investigated. The results show that the low temperature treatment is effective in reducing the retained austenite content and increasing the volume fraction of carbide. The lowest retained austenite content and highest carbide volume fraction were obtained for DCT-196 specimens at the same holding time. Due to the further transformation of martensite and the diffuse distribution of carbides, the microhardness and frictional wear properties of DCT-196 are optimal. Therefore, low temperature treatment can change the microstructure of the case layer of 17Cr2Ni2MoVNb steel and effectively improve the mechanical properties of materials. Full article
(This article belongs to the Special Issue Advances of Ceramic and Alloy Coatings)
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Article
The Influence of Diamond Nanoparticles on Fibroblast Cell Line L929, Cytotoxicity and Bacteriostaticity of Selected Pathogens
Coatings 2022, 12(2), 280; https://doi.org/10.3390/coatings12020280 - 21 Feb 2022
Viewed by 632
Abstract
The main problem with using modified allotrophic forms of carbon with nanodiamond particles in the production of food packaging is establishing the boundary between safety, as it affects the human body, and the adequate and effective action of the substances. One vital area [...] Read more.
The main problem with using modified allotrophic forms of carbon with nanodiamond particles in the production of food packaging is establishing the boundary between safety, as it affects the human body, and the adequate and effective action of the substances. One vital area of concern is the transmission of pathogens in food into the body. The aim of this study was to evaluate the cytotoxicity and bacteriostatic biological activity of two different modifications of diamond nanoparticles: pure detonation nanodiamond particles (DND) obtained by Danienko and plasma-chemically modified detonation nanodiamond particles obtained by the microwave plasma activated chemical vapor deposition method in a rotary chamber (MDP1) An indirect method was used to evaluate the cytotoxicity effect in accordance with ISO 10993–5. The viability of the L929 fibroblast cell line used as a control was 98.5%, for DND 95.14%, and the lowest level of viability for MDP1 was 88.63%. Escherichia coli and Staphylococcus aureus bacteria were used in bacteriostatic tests and the degree of cytotoxicity of the tested materials was classified as low. The in vitro cytotoxicity results indicate no toxic effect on L929 cells nor any effect on any of the samples tested against the bacterial strains us Full article
(This article belongs to the Special Issue Nanodiamond Hybrid Materials: Synthesis and Application)
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Article
Investigation and Accounting Research of VOC in Daily and Specialty Ceramic Industry
Coatings 2022, 12(2), 279; https://doi.org/10.3390/coatings12020279 - 21 Feb 2022
Viewed by 486
Abstract
With the deepening of modernization in China, the situation of air environmental pollution in China is very serious, and the environmental capacity is becoming less and less. Haze has gradually become one of the main sources of pollution in most cities in China. [...] Read more.
With the deepening of modernization in China, the situation of air environmental pollution in China is very serious, and the environmental capacity is becoming less and less. Haze has gradually become one of the main sources of pollution in most cities in China. Volatile organic compounds (VOC) have the activity of participating in photochemical reactions and can participate in a variety of complex reactions in the atmosphere to promote the formation of haze and ozone. Through the experiment of daily ceramic flower paper baking, it can be concluded that the burning loss of flower paper accounts for more than 60% of the total quality of flower paper, and most of them are between 60% and 80%. Among them, the burning loss of PVB flower paper is about 80%, the water transfer paper is about 60%, and the low temperature flower paper is about 86%. In the experiment, the VOC proportion of low temperature flower paper, the PVB paper and water transfer paper accounted for 3.17%, 0.92% and 0.45%, respectively. Through the wax removal experiment of special ceramics molded by hot pressing, it is found that paraffin wax, beeswax and oleic acid are used as binders, and the amount of VOC emitted is also different when the dosage range is different; in addition, the burning loss is generally between 10% and 20% in the process of wax removal. The content of VOC in flue gas is about 0.42%, accounting for 0.046% of special ceramics. It provides an important basis for the calculation of VOC generated during the process of ceramic flower baking. Full article
(This article belongs to the Special Issue Hazardous Materials in the Environment)
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Article
Electron Beam Sintering of Composite Al2O3-ZrO2 Ceramics in the Forevacuum Pressure Range
Coatings 2022, 12(2), 278; https://doi.org/10.3390/coatings12020278 - 20 Feb 2022
Viewed by 455
Abstract
We describe our investigations of electron beam sintering of multilayer ZrO2-Al2O3 composite ceramics in the forevacuum pressure range (~30 Pa). To generate the electron beam, a plasma-cathode electron source operating in the forevacuum pressure range was used; this [...] Read more.
We describe our investigations of electron beam sintering of multilayer ZrO2-Al2O3 composite ceramics in the forevacuum pressure range (~30 Pa). To generate the electron beam, a plasma-cathode electron source operating in the forevacuum pressure range was used; this kind of source provides the capability of direct processing of non-conducting materials. We studied the effect of electron beam sintering on the temperature drop with sample depth for different layer thicknesses and determined the optimal layer thickness to ensure minimal temperature drop. We show that in order to minimize the temperature difference and improve the sintering, it is necessary to take into account the thermophysical parameters of the sintered materials. Forming a layered structure taking into account the coefficient of thermal conductivity of the layer materials allows a reduction in the temperature gradient by 150 °C for samples of 3 mm thickness. Full article
(This article belongs to the Special Issue Electron-Ion-Plasma Technology Applied to Surface Engineering)
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Review
Fluid Films as Models for Understanding the Impact of Inhaled Particles in Lung Surfactant Layers
Coatings 2022, 12(2), 277; https://doi.org/10.3390/coatings12020277 - 19 Feb 2022
Viewed by 695
Abstract
Pollution is currently a public health problem associated with different cardiovascular and respiratory diseases. These are commonly originated as a result of the pollutant transport to the alveolar cavity after their inhalation. Once pollutants enter the alveolar cavity, they are deposited on the [...] Read more.
Pollution is currently a public health problem associated with different cardiovascular and respiratory diseases. These are commonly originated as a result of the pollutant transport to the alveolar cavity after their inhalation. Once pollutants enter the alveolar cavity, they are deposited on the lung surfactant (LS) film, altering their mechanical performance which increases the respiratory work and can induce a premature alveolar collapse. Furthermore, the interactions of pollutants with LS can induce the formation of an LS corona decorating the pollutant surface, favoring their penetration into the bloodstream and distribution along different organs. Therefore, it is necessary to understand the most fundamental aspects of the interaction of particulate pollutants with LS to mitigate their effects, and design therapeutic strategies. However, the use of animal models is often invasive, and requires a careful examination of different bioethics aspects. This makes it necessary to design in vitro models mimicking some physico-chemical aspects with relevance for LS performance, which can be done by exploiting the tools provided by the science and technology of interfaces to shed light on the most fundamental physico-chemical bases governing the interaction between LS and particulate matter. This review provides an updated perspective of the use of fluid films of LS models for shedding light on the potential impact of particulate matter in the performance of LS film. It should be noted that even though the used model systems cannot account for some physiological aspects, it is expected that the information contained in this review can contribute on the understanding of the potential toxicological effects of air pollution. Full article
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Article
Impact Analysis of Initial Cracks’ Angle on Fatigue Failure of Flange Shafts
Coatings 2022, 12(2), 276; https://doi.org/10.3390/coatings12020276 - 18 Feb 2022
Viewed by 456
Abstract
A fatigue test on the failure mode of flange shafts was conducted. The propagation characteristics of the initial crack at the junction between the shaft and the flange as well as its angle effect were studied. This study developed an analysis program of [...] Read more.
A fatigue test on the failure mode of flange shafts was conducted. The propagation characteristics of the initial crack at the junction between the shaft and the flange as well as its angle effect were studied. This study developed an analysis program of fatigue crack propagation, based on the APDL (ANSYS Parametric Design Language). It obtained the effective angle interval within which the initial crack is able to propagate. The fitting calculation formula was derived and the results showed that: (1) The initial crack at the junction between the shaft and the flange would propagate in the radial and axial directions; the unstable crack propagation would cause an abrupt fracture of the cross-section, failing connection; and the angle of initial crack was uncertain. (2) The crack followed the I-II-III mixed mode, which was dominated by mode I. An initial crack with a larger angle showed more noticeable II-III characteristics; KII and KIII affected the crack’s propagation angle in the radial and axial directions and they also affected the structure’s surface direction. (3) The deepest point A of the crack was located at the junction between the shaft and the flange. Its crack propagation can be divided into three stages: rapid growth (stage 1), steady decline (stage 2, buffer stage), and instability (stage 3). The initial crack angle not only affected the propagation rate at stage 1 but also influenced the fatigue life distribution of the structure during propagation. The larger the initial crack angle was, the smaller the proportion of buffer stage in the total fatigue life would be. Moreover, the propagation of crack with a larger initial angle reached instability faster after stage 1, which would cause an abrupt fracture of the cross-section. This was unfavorable for deciding the crack detection time or carrying out maintenance and reinforcement. (4) The crack propagation at the junction between the shaft and the flange was determined by the size relation between ΔKI and ΔKth, instead of the effective stress intensity factor. The effective stress intensity factor can partly reflect the law of crack propagation, but cannot serve as the only criterion for crack propagation; it must be combined with the effective angle interval, which was negatively correlated with the crack’s shape ratio, to determine whether the crack would propagate. Full article
(This article belongs to the Special Issue Corrosion and Degradation of Materials)
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Review
Non-Polar Gallium Nitride for Photodetection Applications: A Systematic Review
Coatings 2022, 12(2), 275; https://doi.org/10.3390/coatings12020275 - 18 Feb 2022
Viewed by 627
Abstract
Ultraviolet photodetectors have been widely utilized in several applications, such as advanced communication, ozone sensing, air purification, flame detection, etc. Gallium nitride and its compound semiconductors have been promising candidates in photodetection applications. Unlike polar gallium nitride-based optoelectronics, non-polar gallium nitride-based optoelectronics have [...] Read more.
Ultraviolet photodetectors have been widely utilized in several applications, such as advanced communication, ozone sensing, air purification, flame detection, etc. Gallium nitride and its compound semiconductors have been promising candidates in photodetection applications. Unlike polar gallium nitride-based optoelectronics, non-polar gallium nitride-based optoelectronics have gained huge attention due to the piezoelectric and spontaneous polarization effect–induced quantum confined-stark effect being eliminated. In turn, non-polar gallium nitride-based photodetectors portray higher efficiency and faster response compared to the polar growth direction. To date, however, a systematic literature review of non-polar gallium nitride-based photodetectors has yet to be demonstrated. Hence, the objective of this systematic literature review is to critically analyze the data related to non-polar gallium nitride-based photodetectors. Based on the pool of literature, three categories are introduced, namely, growth and fabrication, electrical properties, and structural, morphological, and optical properties. In addition, bibliometric analysis, a precise open-source tool, was used to conduct a comprehensive science mapping analysis of non-polar gallium nitride-based photodetectors. Finally, challenges, motivations, and future opportunities of non-polar gallium nitride-based photodetectors are presented. The future opportunities of non-polar GaN-based photodetectors in terms of growth conditions, fabrication, and characterization are also presented. This systematic literature review can provide initial reading material for researchers and industries working on non-polar gallium nitride-based photodetectors. Full article
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Article
Tuning the Electrical Properties of Tungsten Oxide Thin Films Deposited by Reactive Magnetron Sputtering
Coatings 2022, 12(2), 274; https://doi.org/10.3390/coatings12020274 - 18 Feb 2022
Viewed by 689
Abstract
Tungsten oxide films are deposited onto glass and silicon substrates using reactive magnetron sputtering. Several studies have revealed difficulties in studying the electrical properties of resistive WOx films. The main objective of this work is to propose the capacitance meter as a [...] Read more.
Tungsten oxide films are deposited onto glass and silicon substrates using reactive magnetron sputtering. Several studies have revealed difficulties in studying the electrical properties of resistive WOx films. The main objective of this work is to propose the capacitance meter as a method for studying the electrical properties of resistive WOx films. In addition, we aim to establish the correlation between the deposition process and WOx physico-chemical properties. The study of the W-Ar-O2 system hysteresis permitted us to gather the films into four zones, which were delimited by different oxygen flow rate intervals. The identification of these zones was confirmed by the deposition rate, target voltage, chemical composition and electrical properties of the films. A gradual evolution of the capacitance-voltage curves of the metal-oxide-semiconductor structures, with the WOx thin films as the oxide layer, was globally observed with increasing oxygen flow rate. Ion density (Nss) and flat band voltage (Vfb) evolved inversely to oxygen flow rate. The relationship between the evolution of Nss and Vfb and the increase in oxygen flow rate reflects the improvement in oxygen stoichiometry in the WOx films. The WOx-Si interface trap density distribution (Dit) was also studied using the Terman method. It was observed that the films closest to stoichiometry, i.e., WO2 or WO3, showed the lowest values of Dit and Nss. Full article
(This article belongs to the Topic Inorganic Thin Film Materials)
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Article
The Surface Properties of an Aviation Aluminum Alloy after Laser Cleaning
Coatings 2022, 12(2), 273; https://doi.org/10.3390/coatings12020273 - 18 Feb 2022
Viewed by 452
Abstract
In this study, we explored the effects of a laser cleaning process on the surface properties of an aerospace aluminum alloy. We performed surface cleaning on an AA2024 aluminum alloy. Through SEM and EDS analyses on the surface of the aluminum alloy samples [...] Read more.
In this study, we explored the effects of a laser cleaning process on the surface properties of an aerospace aluminum alloy. We performed surface cleaning on an AA2024 aluminum alloy. Through SEM and EDS analyses on the surface of the aluminum alloy samples after cleaning, the cleaning effect on the aluminum alloy under different laser energy densities was studied. After laser cleaning, residual stress, hardness, friction, and wear tests were performed on the aluminum alloy samples. The experimental results demonstrated that the oxides on the surface of AA2024 could be effectively removed when the laser energy density was 10.5 J/cm2. With an increase in the laser energy density, the friction and wear properties of the AA2024 surface could be improved. Laser cleaning could also generate a new hardened layer and residual tensile stress on the surface of AA2024. This article provides a reference for applying laser cleaning in the aerospace field by studying the structure and mechanical properties of an aluminum alloy after laser cleaning. Full article
(This article belongs to the Special Issue State-of-the-Art on Coatings Research in Asia)
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Article
Evolution Law and Mechanism of Freeze–Thaw Damage of Cement-Stabilized Weathered Sand
Coatings 2022, 12(2), 272; https://doi.org/10.3390/coatings12020272 - 18 Feb 2022
Viewed by 495
Abstract
To explore the damage evolution law of cement-stabilized weathered sand under the action of freeze–thaw cycles, relevant experimental research was carried out on stabilized weathered sand with a cement content of 3%, including unconfined compressive strength (UCS), scanning electron microscope (SEM), and mercury [...] Read more.
To explore the damage evolution law of cement-stabilized weathered sand under the action of freeze–thaw cycles, relevant experimental research was carried out on stabilized weathered sand with a cement content of 3%, including unconfined compressive strength (UCS), scanning electron microscope (SEM), and mercury intrusion porosimetry (MIP) testing. Using the surface appearance, mass, and UCS of the specimen, combined with the changes of microscopic characteristics, the freeze–thaw damage law and microscopic degradation mechanism of cement-stabilized weathered sand were analyzed. The test results showed that with the increase of the number of freeze–thaw cycles, the surface appearance of the specimen continued to deteriorate, the unconfined compressive strength gradually decreased, and the mass of the specimen first increased and then decreased. After nine freeze–thaw cycles, the specimen was seriously damaged, and the strength loss was as high as 55%. From a microscopic point of view, the freeze–thaw cycles caused the pore water inside the specimen to continuously change between ice crystals and liquid. Frost heave and shrinkage weakened the cement bond between the weathered sand particles and made the pores in the specimen develop and expand continuously. With the decrease of the number of micropores and the increase of the number of medium and large pores, the particle skeleton changed from a dense structure to a porous structure, which eventually led to the deterioration of the macroscopic properties of the cement-stabilized weathered sand. Full article
(This article belongs to the Special Issue Corrosion and Degradation of Materials)
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Article
Optical Behavior of Curcuminoid Hybrid Systems as Coatings Deposited on Polyester Fibers
Coatings 2022, 12(2), 271; https://doi.org/10.3390/coatings12020271 - 17 Feb 2022
Viewed by 456
Abstract
The recent development of the “eco-friendly” current has brought to the attention of researchers natural dyes that are biodegradable, do not cause allergies and generally have anti-UV protection, and antioxidant and antibacterial properties. In this study, we aimed to obtain hybrid materials of [...] Read more.
The recent development of the “eco-friendly” current has brought to the attention of researchers natural dyes that are biodegradable, do not cause allergies and generally have anti-UV protection, and antioxidant and antibacterial properties. In this study, we aimed to obtain hybrid materials of the dye–host matrix type, by using the sol–gel process. The silica network was generated by tetraethylorthosilicates and modified with organic siloxane derivatives: phenyltriethoxysilane, 3-glycidoxypropyltriethoxysilane, dimethoxydimethylsilane and dimethoxydiphenylsilane. The nanocomposites obtained by embedding curcumin in siloxane matrices were deposited on polyester fabric and evaluated for their properties, relative to the type of organic network modifier used. Fabrics covered with curcuminoid hybrid systems provide a hydrophobic surface, have fluorescent properties and a UPF +50, and, therefore, they can be used in various fields where it is necessary for textiles to provide signaling, self-cleaning or protection properties against ultraviolet radiation. The coated textile materials have very good resistance properties after several repeated washing cycles, and maintain the original UV protection factor at high values even after washing or during rubbing tests. Full article
(This article belongs to the Special Issue Multifunctional Antireflective Coatings and Nanocomposites)
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Article
Comparative Study on Road Performance of Low-Grade Hard Asphalt and Mixture in China and France
Coatings 2022, 12(2), 270; https://doi.org/10.3390/coatings12020270 - 17 Feb 2022
Viewed by 429
Abstract
The high-modulus asphalt mixture produced by hard asphalt has played a good role in reducing asphalt pavement rutting and improving pavement durability. It was widely used in the construction of various levels of road engineering in Europe. However, low-grade hard asphalt was rarely [...] Read more.
The high-modulus asphalt mixture produced by hard asphalt has played a good role in reducing asphalt pavement rutting and improving pavement durability. It was widely used in the construction of various levels of road engineering in Europe. However, low-grade hard asphalt was rarely used in road engineering in China, and the use of hard asphalt for the design and construction of high modulus asphalt mixtures lacks sufficient engineering experience. Considering the above issues, comparative research on the performance of Chinese and French low-grade hard asphalt and mixture was carried out. In this paper, the performance of French 15# hard asphalt commonly used for EME (Enrobés à Module Elevé Class) high modulus asphalt mixture and China 15# hard asphalt was analyzed comparatively, where six typical high modulus asphalt mixtures corresponding to two low-grade hard asphalts were designed referring to the design requirements of French high modulus asphalt mixtures. The road performance of a high-modulus asphalt mixture was evaluated to verify the feasibility of its application in engineering. The research results show that the performance indicators of both Chinese and French asphalts meet the requirements of binder materials used in high modulus asphalt mixtures, and the performance of their corresponding mixtures of the two asphalts also meet the specifications of high modulus asphalt mixtures. However, the two asphalts and the performance of their corresponding mixture are slightly different. The high modulus asphalt mixture of Chinese low-grade hard bitumen can be used well in road engineering applications in China. It can strongly promote the wide application of high modulus asphalt mixture in China. Full article
(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)
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Article
Hardness Enhancement in CoCrFeNi1−x(WC)x High-Entropy Alloy Thin Films Synthesised by Magnetron Co-Sputtering
Coatings 2022, 12(2), 269; https://doi.org/10.3390/coatings12020269 - 17 Feb 2022
Viewed by 497
Abstract
We demonstrate the systematic hardness enhancement of the CoCrFeNi high-entropy alloy (HEA) by the addition of tungsten carbide (WC). Mixed thin films are fabricated by magnetron co-sputtering using a home-made spark plasma-sintered CoCrFeNi target and a commercially available WC target. The WC content [...] Read more.
We demonstrate the systematic hardness enhancement of the CoCrFeNi high-entropy alloy (HEA) by the addition of tungsten carbide (WC). Mixed thin films are fabricated by magnetron co-sputtering using a home-made spark plasma-sintered CoCrFeNi target and a commercially available WC target. The WC content in the thin films is adjusted via the ratio of deposition powers applied to the targets. X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX) measurements were taken to determine the surface and bulk stoichiometry, respectively. The uniform distribution of the elements is confirmed via EDX mapping. X-ray diffraction (XRD) is carried out on the samples to determine the crystal phase formation. The Vickers hardness of the thin films is investigated using nanoindentation and shows an increase in the hardness in the thin films following an increased WC content. The data obtained are presented in comparison to pure WC and CoCrFeNi thin films fabricated by magnetron sputtering, respectively. Full article
(This article belongs to the Special Issue High-Entropy Alloy Coatings and Surface Functionalization)
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Article
The Engineering Properties and Microscopic Characteristics of High-Liquid-Limit Soil Improved with Lignin
Coatings 2022, 12(2), 268; https://doi.org/10.3390/coatings12020268 - 17 Feb 2022
Viewed by 398
Abstract
To improve the engineering performance of high-liquid-limit soil, lignin, a by-product of the papermaking industry, was used. First, the influence of lignin content and curing age on the physicochemical and mechanical properties of the improved soil was determined by carrying out pH, Atterberg [...] Read more.
To improve the engineering performance of high-liquid-limit soil, lignin, a by-product of the papermaking industry, was used. First, the influence of lignin content and curing age on the physicochemical and mechanical properties of the improved soil was determined by carrying out pH, Atterberg limits, heavy compaction, unconfined compressive strength (UCS), California bearing ratio (CBR), and resilience modulus tests. Secondly, microscopic images obtained by scanning electron microscopy (SEM) were analyzed. The characteristic and evolution rules of the microstructure were expounded for the improved soil. Finally, combining SEM with energy-dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) analysis, the mechanism of lignin improvement on high-liquid-limit clay is discussed from the perspective of molecular structure. The results showed that the pH value of lignin-improved soil was much lower than that of quicklime-improved soil, which were 7.0 and 11.7, respectively. When the lignin content was 3%, the dry density and mechanical indexes (UCS, CBR, and resilience modulus) of the improved soil all showed the maximum values. From the perspective of microstructure, the connection between soil particles was strengthened through the wrapping and filling of the flocculent cementing materials produced by lignin. The improvement mechanism of lignin on soil was the combined result of ion exchange, hydrogen bonding, covalent bonding, and electrostatic attraction. Full article
(This article belongs to the Section Environmental Aspects in Colloid and Interface Science)
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Review
Review on Development and Application of 3D-Printing Technology in Textile and Fashion Design
Coatings 2022, 12(2), 267; https://doi.org/10.3390/coatings12020267 - 16 Feb 2022
Cited by 1 | Viewed by 1130
Abstract
Three-dimensional printing (3DP) allows for the creation of highly complex products and offers customization for individual users. It has generated significant interest and shows great promise for textile and fashion design. Here, we provide a timely and comprehensive review of 3DP technology for [...] Read more.
Three-dimensional printing (3DP) allows for the creation of highly complex products and offers customization for individual users. It has generated significant interest and shows great promise for textile and fashion design. Here, we provide a timely and comprehensive review of 3DP technology for the textile and fashion industries according to recent advances in research. We describe the four 3DP methods for preparing textiles; then, we summarize three routes to use 3DP technology in textile manufacturing, including printing fibers, printing flexible structures and printing on textiles. In addition, the applications of 3DP technology in fashion design, functional garments and electronic textiles are introduced. Finally, the challenges and prospects of 3DP technology are discussed. Full article
(This article belongs to the Special Issue Surface Treatment of Textiles Vol. 2)
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Article
Template Electrochemical Synthesis of Hydroxyapatite on a Titania–Silver Composite Surface for Potential Use in Implantology
Coatings 2022, 12(2), 266; https://doi.org/10.3390/coatings12020266 - 16 Feb 2022
Viewed by 663
Abstract
Modern materials science, both in terms of functional and structural materials, is actively developing towards the creation of structures with a given ordering. A wide range of methods involves ordering the structure according to a template shape. Template synthesis is one of the [...] Read more.
Modern materials science, both in terms of functional and structural materials, is actively developing towards the creation of structures with a given ordering. A wide range of methods involves ordering the structure according to a template shape. Template synthesis is one of the mots wide-spread approaches. Most often, the template synthesis method is implemented under conditions of limiting the growth of the phase due to the geometry of the template. In the present work, a template electrochemical method is considered for calcium hydroxyapatite (HAp) coating synthesis, based on the replication of the planar template texture during deposition. In this case, the template is an array of silver microparticles immobilized on an electrically conductive substrate, separated by an insulator layer. The developed approach is similar to the mask metallization widely used in planar technology. In this work, the possibility of the template pulsed electrodeposition of ceramics rather than metal is shown using HAp as an example. This approach is interesting for materials science, in particular, for obtaining micro-ordered hydroxyapatite structures—a crystallochemical analogue of the inorganic bone tissue component—on the surface of bone implants, which can be implemented to improve their biomedical characteristics. As a result of our study, we experimentally determined the conditions for obtaining the composite coating TiO2/Ag/Ca10(PO4)6(OH)2 with controlled phase structure, topology and localization of components on the surface, which was confirmed by Scanning Electron Microscopy, Energy Dispersive Spectroscopy, and X-ray Diffraction (SEM, EDS and XRD). The absence of cytotoxicity for the osteoblast-like cells of the developed coating was revealed by cytological tests. Full article
(This article belongs to the Special Issue Bioactive Coatings on Medical Implants)
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Article
A Cross-Sectional Study for Association between Periodontitis and Benign Prostatic Hyperplasia Using the Korean Genome and Epidemiology Study Data
Coatings 2022, 12(2), 265; https://doi.org/10.3390/coatings12020265 - 16 Feb 2022
Viewed by 581
Abstract
Recently, several studies have suggested the relationship between periodontitis and prostatic disease. However, epidemiological studies on the association between periodontitis and benign prostatic hyperplasia (BPH) are scarce. Hence, we aimed to identify the association between the two diseases using data from the Korean [...] Read more.
Recently, several studies have suggested the relationship between periodontitis and prostatic disease. However, epidemiological studies on the association between periodontitis and benign prostatic hyperplasia (BPH) are scarce. Hence, we aimed to identify the association between the two diseases using data from the Korean Genome and Epidemiology Study. Among the 173,209 participants, 3297 men with periodontitis and 35,292 controls (without periodontitis) were selected. The history of BPH in participants with periodontitis and the controls were also investigated. Two-tailed analyses, independent t-tests, and chi-square tests were used for statistical analysis. The adjusted odds ratio (OR) for BPH was 1.50 (95% confidence interval, 1.35–1.68; p < 0.001) after adjusting for past medical histories. The adjusted OR for BPH was 1.57 (95% confidence interval, 1.41–1.76; p < 0.001) after adjusting for anthropometric and laboratory data. Collectively, this study provides evidence that periodontitis is associated with BPH. This finding supports the use of regular dental checkups and periodontal treatments to reduce the prevalence and progression of BPH. Full article
(This article belongs to the Special Issue Implants and Its Protection)
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Review
Research Status of Graphene Polyurethane Composite Coating
Coatings 2022, 12(2), 264; https://doi.org/10.3390/coatings12020264 - 16 Feb 2022
Viewed by 717
Abstract
Graphene material has a variety of excellent properties and applications in energy storage, biomaterials, photoelectric devices, and other fields. With the progress of nanotechnology, graphene nanomaterials have shown their advantages in the field of new nano-corrosion coatings with their high barrier structure. In [...] Read more.
Graphene material has a variety of excellent properties and applications in energy storage, biomaterials, photoelectric devices, and other fields. With the progress of nanotechnology, graphene nanomaterials have shown their advantages in the field of new nano-corrosion coatings with their high barrier structure. In addition, polyurethane is also widely used in the field of anti-corrosion coatings due to its excellent chemical resistance, mechanical properties, and weathering resistance. The preparation of composite coatings by combining graphene nanomaterials with traditional polyurethane (PU) coatings has opened up a new way for the research and development of new anticorrotic coatings. In this paper, graphene polyurethane composite coating was first used as the research object, and the mechanism of graphene material in the new composite coating was analyzed. Then, graphene oxide (GO), a commonly used precursor material, was used as an entry point for a detailed study of the properties of GO materials and the advantages and disadvantages of its application in composites, and two types of modifications, covalent and non-covalent, were analyzed. In addition, the preparation methods and processes of graphene polyurethane composite coatings were summarized. Finally, the future research directions and research focus of GO were prospected. Full article
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Article
Effect of Gas Propellant Temperature on the Microstructure, Friction, and Wear Resistance of High-Pressure Cold Sprayed Zr702 Coatings on Al6061 Alloy
Coatings 2022, 12(2), 263; https://doi.org/10.3390/coatings12020263 - 16 Feb 2022
Cited by 1 | Viewed by 648
Abstract
For the first time, Zr702 coatings were deposited onto an Al6061 alloy using a high-pressure cold spray (HPCS) system. In this work, five different N2 process gas temperatures between 700 and 1100 °C were employed to understand the formation of cold sprayed [...] Read more.
For the first time, Zr702 coatings were deposited onto an Al6061 alloy using a high-pressure cold spray (HPCS) system. In this work, five different N2 process gas temperatures between 700 and 1100 °C were employed to understand the formation of cold sprayed (CS) Zr coatings and their feasibility for enhanced wear resistance. Results indicated that the N2 processing gas temperature of about 1100 °C enabled a higher degree of particle thermal softening, which created a dense, robust, oxide- and defect-free Zr coating. Across all CS Zr coatings, there was a refinement of crystallinity, which was attributed to the severe localized plastic deformation of the powder particles. The enhanced thermal boost up zone at the inter-particle boundaries and decreased recoverable elastic strain were accountable for the inter-particle bonding of the coatings at higher process gas temperatures. The flattening ratio (ε) increased as a function of temperature, implying that there was a greater degree of plastic deformation at higher N2 gas temperatures. The microhardness readings and wear volume of the coatings were also improved as a function of process gas temperature. In this work, the wear of the Al6061 alloy substrate was mainly plowing-based, whereas the Zr CS substrates demonstrated a gradual change of abrasive to adhesive wear. From our findings, the preparation of CS Zr coatings was a feasible method of enhancing the wear resistance of Al-based alloys. Full article
(This article belongs to the Special Issue Surface Modification of Light Alloys by Protective Coatings)
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Article
Effect of Ammonia Addition on the Growth of an AlO(OH) Film during Steam Coating Process
Coatings 2022, 12(2), 262; https://doi.org/10.3390/coatings12020262 - 16 Feb 2022
Viewed by 563
Abstract
Al alloys possess excellent physical and mechanical properties, such as low density, high specific strength, and good ductility. However, their low corrosion resistance limits their use in corrosive environments. The steam coating process has attracted considerable attention as a new coating technology that [...] Read more.
Al alloys possess excellent physical and mechanical properties, such as low density, high specific strength, and good ductility. However, their low corrosion resistance limits their use in corrosive environments. The steam coating process has attracted considerable attention as a new coating technology that can improve the corrosion resistance of Al alloys. This surface treatment technology uses steam to form a corrosion-resistant film on Al alloys. However, a decrease in the processing time, which can result in a lower cost, is needed for the practical application of the steam coating process. In this study, an Al-Mg-Si alloy is used as the base material, and ammonia is added to the steam source to increase the film formation rate. By adding ammonia (0.5 mol/L) to the steam source, the rate constant, K, for film formation increases 1.82 times compared to that of the pure-water-only treatment. Field emission scanning electron micrographs of the film surface confirms that the crystal morphologies of the crystals change from rectangular to parallelepiped shape with increasing process time by ammonia addition. Furthermore, X-ray diffraction patterns show that AlO(OH) crystals are successfully synthesized without byproducts, even when ammonia is added. Full article
(This article belongs to the Special Issue Science and Engineering of Coating)
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Article
MOCVD of II-VI HRT/Emitters for Voc Improvements to CdTe Solar Cells
Coatings 2022, 12(2), 261; https://doi.org/10.3390/coatings12020261 - 16 Feb 2022
Viewed by 553
Abstract
CdTe solar cells were produced using metal organic chemical vapour deposition (MOCVD), which employed a (Zn,Al)S (AZS) high resistant transparent (HRT) layer at the transparent conducting oxide (TCO)/Cd(Zn)S emitter interface, to enable the higher annealing temperature of 440 °C to be employed in [...] Read more.
CdTe solar cells were produced using metal organic chemical vapour deposition (MOCVD), which employed a (Zn,Al)S (AZS) high resistant transparent (HRT) layer at the transparent conducting oxide (TCO)/Cd(Zn)S emitter interface, to enable the higher annealing temperature of 440 °C to be employed in the chlorine heat treatment (CHT) process. The AZS HRT remained intact with conformal coverage over the TCO after performing the high CHT annealing, confirmed by cross-section scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy (STEM-EDX) characterisation, which also revealed the Cd(Zn)S emitter layer having been consumed by the CdTe absorber via interdiffusion. The more aggressive CHT resulted in large CdTe grains. The combination of AZS HRT and aggressive CHT increased open circuit voltage (Voc) and improved solar cell performance. Full article
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