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Coatings, Volume 13, Issue 5 (May 2023) – 163 articles

Cover Story (view full-size image): Amorphous carbon coatings have attracted the community's attention due to their exciting properties: high hardness, good wear resistance, low friction coefficient, transparency, wide band gap, chemical inertness, and biocompatibility. The need to produce a-C films on an industrial scale has prompted efforts to use magnetron sputtering techniques. The fabrication of a-C layers with enhanced sp3 bonds requires the use of special techniques. One such unique technique is Gas Injection Magnetron Sputtering. In this technique, the synthesis of a-C layers is controlled by small gas impulses. It has the extraordinary advantage of limiting the dissipation of the kinetic energy of the plasma species excited at a lower pressure than in standard magnetron sputtering. View this paper
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13 pages, 3344 KiB  
Article
Complex Bioactive Chitosan–Bioglass Coatings on a New Advanced TiTaZrAg Medium–High-Entropy Alloy
by Andrei Bogdan Stoian, Radu Nartita, Georgeta Totea, Daniela Ionita and Cristian Burnei
Coatings 2023, 13(5), 971; https://doi.org/10.3390/coatings13050971 - 22 May 2023
Viewed by 1137
Abstract
High-entropy alloys (HEAs), also known as multicomponent or multi-principal element alloys (MPEAs), differ from traditional alloys, which are usually based only on one principal element, in that they are usually fabricated from five or more elements in large percentages related to each other, [...] Read more.
High-entropy alloys (HEAs), also known as multicomponent or multi-principal element alloys (MPEAs), differ from traditional alloys, which are usually based only on one principal element, in that they are usually fabricated from five or more elements in large percentages related to each other, in the range of 5%–35%. Despite the usually outstanding characteristics of HEAs, based on a properly selected design, many such alloys are coated with advanced composites after their elaboration to further improve their qualities. In this study, 73Ti-20Zr-5Ta-2Ag samples were covered with chitosan and a mixture of chitosan, bioglass, and ZnO particles to improve the materials’ antibacterial properties. A variety of methods, including scanning electron microscopy, atomic force microscopy, and mechanical and electrochemical determinations, has permitted a quantified comparison between the coated and uncoated surfaces of this medium–high-entropy alloy. The materials’ properties were enhanced by the complex coating, giving the alloys not only high antibacterial activity, but also good corrosion protection. Full article
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10 pages, 1582 KiB  
Article
Effects of MDF Substrate Surface Coating Process on UV Inkjet Print Quality
by Ruijuan Sang, Shuqi Yang and Zhenxian Fan
Coatings 2023, 13(5), 970; https://doi.org/10.3390/coatings13050970 - 22 May 2023
Cited by 3 | Viewed by 1152
Abstract
The structural properties and whiteness of the substrate surface markedly effect printing quality and are closely related to the primer coating processes. Herein, four different roller coating schemes were applied on MDF surfaces to change their structural properties and color, and the whiteness, [...] Read more.
The structural properties and whiteness of the substrate surface markedly effect printing quality and are closely related to the primer coating processes. Herein, four different roller coating schemes were applied on MDF surfaces to change their structural properties and color, and the whiteness, gloss, and roughness properties of the substrate surfaces were characterized for UV inkjet printing. Data analysis was conducted to explore the effects of these variables on the color reproduction, relative contrast, and printing gloss of the MDF substrates. The results showed that, according to CMYK, L*a*b* values and spectral reflectance data, the finishing of the MDF substrate with a 40 g/m2 layer of transparent primer combined with three layers of white primer at 20 g/m2 per roll coating layer had the best color reproduction effect for UV inkjet printing. Regarding the effects of relative contrast, the correlation with whiteness and glossiness was significant, while the correlation with glossiness was minor. The inkjet printing gloss value was positively correlated with substrate primer surface whiteness, while it was negatively correlated with roughness. When the surface whiteness of the substrate was relatively high, the roughness was lower and the printing effects were glossier. We sought to optimize the printing effects of all aspects of the MDF substrate by primer coating. The results of this work provide a feasible application method to improve printing quality and enhance the added value of low-quality boards, as well as to further expand the application of UV inkjet printing in the wood decoration market. Full article
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3 pages, 2200 KiB  
Editorial
Coatings 2023 Best Paper Award (Article): Announcement and Interview with the Winning Team
by Coatings Editorial Office
Coatings 2023, 13(5), 969; https://doi.org/10.3390/coatings13050969 - 22 May 2023
Viewed by 808
Abstract
The Coatings Editorial Board and Editorial Team would like to congratulate the winner of the Coatings 2023 Best Paper Award (Article) [...] Full article
3 pages, 464 KiB  
Editorial
Coatings 2023 Best Paper Award (Review): Announcement and Interview with the Winning Team
by Coatings Editorial Office
Coatings 2023, 13(5), 968; https://doi.org/10.3390/coatings13050968 - 22 May 2023
Viewed by 561
Abstract
The Coatings Editorial Board and Editorial Team would like to congratulate the winner of the Coatings 2023 Best Paper Award (Review) [...] Full article
11 pages, 4358 KiB  
Article
Effect of HfO2 Particles on Ceramic Coating Fabricated on Ti6Al4V Alloy via Plasma Electrolytic Oxidation
by Manxi Sun, Meiling Jiang, Hongjian Huang, Biao Yang, Yuhang Lin and Ping Wang
Coatings 2023, 13(5), 967; https://doi.org/10.3390/coatings13050967 - 22 May 2023
Cited by 2 | Viewed by 1000
Abstract
Hafnium dioxide (HfO2) has a wide bandgap and high dielectric constant. We prepared ceramic coatings on Ti6Al4V alloys via plasma electrolytic oxidation (PEO) in an electrolyte with HfO2 particles. The influence of the HfO2 particles on the microstructure, phase [...] Read more.
Hafnium dioxide (HfO2) has a wide bandgap and high dielectric constant. We prepared ceramic coatings on Ti6Al4V alloys via plasma electrolytic oxidation (PEO) in an electrolyte with HfO2 particles. The influence of the HfO2 particles on the microstructure, phase composition, elemental distribution, and corrosion resistance of the PEO coatings was systematically investigated. The results showed that the addition of HfO2 increased the oxidation voltage (from 462 to 472 V) and promoted the microarc sintering reaction so that the thickness and hardness of the resulting PEO coating increased. Moreover, the quantity of the micropores on the coating surface caused by the discharge decreased after adding the HfO2 particles. The X-ray diffraction patterns confirmed that the HfO2 particles were incorporated into the coating by remelting and sintering the microarc. Furthermore, the corrosion resistance of the PEO coating was remarkably increased after introducing HfO2, which was attributed to the increase in the electrode potential and the densification of the coating structure. Full article
(This article belongs to the Section Corrosion, Wear and Erosion)
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18 pages, 7999 KiB  
Article
Electronic and Electrical Properties of Island-Type Hybrid Structures Based on Bi-Layer Graphene and Chiral Nanotubes: Predictive Analysis by Quantum Simulation Methods
by Michael M. Slepchenkov, Pavel V. Barkov and Olga E. Glukhova
Coatings 2023, 13(5), 966; https://doi.org/10.3390/coatings13050966 - 22 May 2023
Viewed by 1001
Abstract
Hybrid structures based on graphene and carbon nanotubes (CNTs) are one of the most relevant modern nanomaterials for applications in various fields, including electronics. The variety of topological architectures of graphene/CNT hybrids requires a preliminary study of their physical properties by in silico [...] Read more.
Hybrid structures based on graphene and carbon nanotubes (CNTs) are one of the most relevant modern nanomaterials for applications in various fields, including electronics. The variety of topological architectures of graphene/CNT hybrids requires a preliminary study of their physical properties by in silico methods. This paper is devoted to the study of the electronic and electrical properties of graphene/CNT hybrid 2D structures with an island topology using the self-consistent charge density functional-based tight-binding (SCC-DFTB) formalism and the Landauer–Buttiker formalism. The island-type topology is understood as the atomic configuration of a graphene/CNT hybrid film, in which the structural fragments of graphene and nanotubes form “islands” (regions of the atomic structure) with an increased density of carbon atoms. The island-type graphene/CNT hybrid structures are formed by AB-stacked bilayer graphene and (6,3)/(12,8) chiral single-walled carbon nanotubes (SWCNT). The bilayer graphene is located above the nanotube perpendicular to its axis. Based on the binding energy calculations, it is found that the atomistic models of the studied graphene/SWCNT hybrid structures are thermodynamically stable. The peculiarities of the band structure of graphene/SWCNT (6,3) and graphene/SWCNT (12,8) hybrid structures are analyzed. It is shown that the electronic properties of graphene/SWCNT hybrid structures are sensitive to the orientation and size of the graphene layers with respect to the nanotube surface. It is found that an energy gap of ~0.1 eV opens in the band structure of only the graphene/SWCNT (6,3) hybrid structure, in which the graphene layers of the same length are arranged horizontally above the nanotube surface. We revealed the electrical conductivity anisotropy for all considered atomistic models of the graphene/SWCNT (12,8) hybrid structure when bilayer graphene sheets with different sizes along the zigzag and armchair directions are located at an angle with respect to the nanotube surface. The obtained knowledge is important to evaluate the prospects for the potential application of the considered atomic configurations of graphene/SWCNT hybrid structures with island-type topology as connecting conductors and electrodes in electronic devices. Full article
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7 pages, 2819 KiB  
Article
The Advantages of Double Catalytic Layers for Carbon Nanotube Growth at Low Temperatures (<400 °C) in 3D Stacking and Power Applications
by Hong-Yi Lin, Nilabh Basu, Min-Hung Lee, Sheng-Chi Chen and Ming-Han Liao
Coatings 2023, 13(5), 965; https://doi.org/10.3390/coatings13050965 - 22 May 2023
Viewed by 1135
Abstract
A double catalytic layer scheme is proposed and investigated for the low temperature growth of carbon nanotubes (CNTs) over Co (Cobalt), Al (Aluminum), and Ti (Titanium) catalysts on a silicon substrate. In this work, we demonstrate the growth of CNTs by a thermal [...] Read more.
A double catalytic layer scheme is proposed and investigated for the low temperature growth of carbon nanotubes (CNTs) over Co (Cobalt), Al (Aluminum), and Ti (Titanium) catalysts on a silicon substrate. In this work, we demonstrate the growth of CNTs by a thermal chemical vapor deposition (TCVD) process at both 350 °C and 400 °C. Based on scanning electron microscopy (SEM) and Raman spectroscopy analyses, the good quality of the CNTs is demonstrated. This study contributes to the on-going research on integrating semiconductors into packaging and power-related applications, as demonstrated with the low resistance (~128 Ω) and high thermal conductivity (~29.8 Wm−1 K−1) of our developed CNTs. Full article
(This article belongs to the Special Issue Research on Electronic Packaging Materials)
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15 pages, 5800 KiB  
Article
Effect of Heat Treatment on the Passive Film and Depassivation Behavior of Cr-Bearing Steel Reinforcement in an Alkaline Environment
by Yuwan Tian, Cheng Wen, Xiaohui Xi, Deyue Yang and Peichang Deng
Coatings 2023, 13(5), 964; https://doi.org/10.3390/coatings13050964 - 22 May 2023
Viewed by 1281
Abstract
Using Cr-bearing low-alloy steel is an effective preventive measure for marine structures, as it offers superior corrosion resistance when compared to plain carbon steel. However, it remains unclear how quenching and tempering heat treatment, which is commonly applied to steel reinforcement in some [...] Read more.
Using Cr-bearing low-alloy steel is an effective preventive measure for marine structures, as it offers superior corrosion resistance when compared to plain carbon steel. However, it remains unclear how quenching and tempering heat treatment, which is commonly applied to steel reinforcement in some specific environments to improve its mechanical properties, affects its corrosion resistance. In the present work, the impact of heat treatment on the passive film and depassivation behavior of the 0.2C-1.4Mn-0.6Si-5Cr steel are studied. The results reveal that quenching and tempering result in grain refinement of the Cr-bearing steel, which increases its hardness. However, this refinement causes significant degradation in its corrosion resistance. The critical [Cl]/[OH] ratio after quenching and tempering is determined to be approximately 6.6 times lower than that after normalization, and the corrosion rate is 1.6 times higher. After quenching and tempering, the passive film predominantly comprises iron oxides and hydroxides, with relatively high water content and defect density. Additionally, the FeII/FeIII ratio and film resistance are relatively low. In comparison, after normalization, the steel exhibits high corrosion resistance, with the passive film formed offering the highest level of protection. Full article
(This article belongs to the Topic Alloys and Composites Corrosion and Mechanical Properties)
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24 pages, 8332 KiB  
Article
Influence of Silver-Coated Tool Electrode on Electrochemical Micromachining of Incoloy 825
by Geethapriyan Thangamani, Muthuramalingam Thangaraj, Palani Iyamperumal Anand, Mani Jayakumar, Nikolaos E. Karkalos, Emmanouil L. Papazoglou and Panagiotis Karmiris-Obratański
Coatings 2023, 13(5), 963; https://doi.org/10.3390/coatings13050963 - 21 May 2023
Cited by 2 | Viewed by 1157
Abstract
Incoloy 825 alloy is often used in calorifiers, propeller shafts, and tank vehicles owing to the improved resistance to aqueous corrosion. The electrochemical micromachining process can be utilized to machine such an engineering material owing to higher precision and lower tool wear. In [...] Read more.
Incoloy 825 alloy is often used in calorifiers, propeller shafts, and tank vehicles owing to the improved resistance to aqueous corrosion. The electrochemical micromachining process can be utilized to machine such an engineering material owing to higher precision and lower tool wear. In the present study, an investigation was performed to enhance the process of creating micro-holes using silver-coated copper tool electrodes. The sodium nitrate electrolyte was used under different levels of input parameters such as voltage, electrolyte concentration, frequency, and duty cycle with a view to improving material removal rate, conicity, overcut, and circularity. It was found that silver-coated copper tool electrode had a high material removal rate (MRR), better overcut, conicity, and circularity compared to uncoated copper tools in most cases, due to its high corrosive resistance and electrical conductivity. From SEM and EDS analysis, it was observed that better surface topography of the micro-holes is obtained with silver-coated copper tool electrode while machining Incoloy 825 alloy in the micromachining process. Full article
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18 pages, 13890 KiB  
Article
Aluminium-Based Dissimilar Alloys Surface Composites Reinforced with Functional Microparticles Produced by Upward Friction Stir Processing
by Filipe Moreira, Pedro M. Ferreira, Rui J. C. Silva, Telmo G. Santos and Catarina Vidal
Coatings 2023, 13(5), 962; https://doi.org/10.3390/coatings13050962 - 21 May 2023
Cited by 5 | Viewed by 1446
Abstract
Surface metal matrix composites offer an excellent solution for applications where surface properties play a crucial role in components’ performance and durability, such as greater corrosion resistance, better wear resistance, and high formability. Solid-state processing techniques, such as friction surfacing and friction stir [...] Read more.
Surface metal matrix composites offer an excellent solution for applications where surface properties play a crucial role in components’ performance and durability, such as greater corrosion resistance, better wear resistance, and high formability. Solid-state processing techniques, such as friction surfacing and friction stir welding/processing, offer several advantages over conventional liquid-phase processing methods. This research investigated the feasibility of producing surface composites of aluminium-based dissimilar alloys reinforced with functional microparticles through experimental validation, determined the process parameters that resulted in a more homogeneous distribution of the particles in the surface composites, and enhanced the understanding of Upward Friction Stir Processing (UFSP) technology. The production of aluminium-based dissimilar alloys (AA 7075-T651 and AA 6082-T651) surface composites reinforced with SiC particles was studied, and it was concluded that the macrography and micrography analyses, scanning electron microscopy (SEM) analysis, microhardness measurements, and eddy currents technique reveal an extensive and homogeneous incorporation of SiC particles. In the stirred zone, a decrease of approximately 20 HV 0.5 in hardness was observed compared to the base material. This reduction is attributed to the weakening effect caused by low-temperature annealing during UFSP, which reduces the strengthening effect of the T651 heat treatment. Additionally, the presence of particles did not affect the surface composite hardness in the stirred zone. Furthermore, despite the presence of significant internal defects, SEM analyses revealed evidence of the lower alloy merging with the upper zone, indicating that the lower plate had a role beyond being merely sacrificial. Therefore, the production of bimetallic composites through UFSP may offer advantages over composites produced from a monometallic matrix. The results of the eddy currents testing and microhardness measurements support this finding and are consistent with the SEM/EDS analyses. Full article
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10 pages, 3224 KiB  
Article
Drive Type Virtual Reality Image on a Head-Mounted Display
by Yoichi Ogata
Coatings 2023, 13(5), 961; https://doi.org/10.3390/coatings13050961 - 20 May 2023
Viewed by 1023
Abstract
We fabricate a head-mounted display (HMD) providing a gradation VR image generated at the surface by using the excitation of the guided mode in a TiO2-slanted nanograting layer. In the TiO2 layer, the beam is waveguided along the short axis [...] Read more.
We fabricate a head-mounted display (HMD) providing a gradation VR image generated at the surface by using the excitation of the guided mode in a TiO2-slanted nanograting layer. In the TiO2 layer, the beam is waveguided along the short axis direction of the grating at a specific injection angle Θ. On the surface of the layer, a beam consisting of leakage generated during the waveguide is emitted. It generates an intensity gradient image for the waveguide direction. In this work, we convert this gradation image to VR by using another coupler. Finally, the obtained gradation VR image is also discussed. Full article
(This article belongs to the Special Issue Advanced Materials for Electrocatalysis and Energy Storage)
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16 pages, 10919 KiB  
Article
Atomic Layer Deposition of Chlorine Containing Titanium–Zinc Oxide Nanofilms Using the Supercycle Approach
by Denis Nazarov, Lada Kozlova, Aida Rudakova, Elena Zemtsova, Natalia Yudintceva, Elizaveta Ovcharenko, Alexandra Koroleva, Igor Kasatkin, Ludmila Kraeva, Elizaveta Rogacheva and Maxim Maximov
Coatings 2023, 13(5), 960; https://doi.org/10.3390/coatings13050960 - 20 May 2023
Cited by 2 | Viewed by 1551
Abstract
Atomic layer deposition (ALD) is a useful tool for producing ultrathin films and coatings of complex composition with high thickness control for a wide range of applications. In this study, the growth of zinc–titanium oxide nanofilms was investigated. Diethyl zinc, titanium tetrachloride, and [...] Read more.
Atomic layer deposition (ALD) is a useful tool for producing ultrathin films and coatings of complex composition with high thickness control for a wide range of applications. In this study, the growth of zinc–titanium oxide nanofilms was investigated. Diethyl zinc, titanium tetrachloride, and water were used as precursors. The supercycle approach was used, and wide ZnO/TiO2 (ZTO) ALD cycles were prepared: 5/1, 3/1, 2/1, 1/1, 1/2, 1/3, 1/5, 1/10, 1/20. Spectral ellipsometry, X-ray reflectometry, X-ray diffraction, scanning electron microscopy, SEM-EDX, and contact angle measurements were used to characterize the thickness, morphology, and composition of the films. The results show that the thicknesses of the coatings differ considerably from those calculated using the rule of mixtures. At high ZnO/TiO2 ratios, the thickness is much lower than expected and with increasing titanium oxide content the thickness increases significantly. The surface of the ZTO samples contains a significant amount of chlorine in the form of zinc chloride and an excessive amount of titanium. The evaluation of the antibacterial properties showed significant activity of the ZTO–1/1 sample against antibiotic-resistant strains and no negative effect on the morphology and adhesion of human mesenchymal stem cells. These results suggest that by tuning the surface composition of ALD-derived ZTO samples, it may be possible to obtain a multi-functional material for use in medical applications. Full article
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15 pages, 13973 KiB  
Article
Tribological Properties of TiN Coating on Cotton Picker Spindle
by Peng Pan, Jie Gao, Chaorun Si, Qiang Yao, Zhanhong Guo and Youqiang Zhang
Coatings 2023, 13(5), 959; https://doi.org/10.3390/coatings13050959 - 20 May 2023
Viewed by 974
Abstract
The spindle is the key working part of the horizontal cotton picker, and the wear resistance of its surface directly affects the service life of the spindle. Improving the surface performance of the spindle is fundamental for improving the performance of cotton pickers. [...] Read more.
The spindle is the key working part of the horizontal cotton picker, and the wear resistance of its surface directly affects the service life of the spindle. Improving the surface performance of the spindle is fundamental for improving the performance of cotton pickers. To enhance the wear resistance of the spindle surface, this study used the physical vapor deposition (PVD) technique to prepare TiN coating on the spindle substrate surface of the cotton-picking machine to improve the spindle surface rather than the original electroplated chromium coating. The microscopic morphology of the spindle was analyzed by scanning electron microscope (SEM), the mechanical and frictional properties of the spindle were tested by a nanoindentation tester and a friction wear tester, and the morphology of the worn spindle was observed by a portable microscope and a 3D surface profiler. The test results indicated that after the PVD treatment, the surface hardness of the spindle was about 2.5 times that of the electroplated chromium spindle, and the H/E value was 2.2 times that of the electroplated chromium spindle. PVD-TiN spindle showed better mechanical properties. In the friction test, under the same conditions, the wear rate of the PVD-TiN spindle was less than that of the chrome plating spindle. In a field test of 100 hm2, the average wear area of the second tooth tip surface of the electroplated chromium spindle was about 2.17 times that of the PVD-TiN spindle. It was verified that the PVD-TiN spindle surface had better wear resistance than the electroplated chromium spindle. This study has certain research significance for the performance optimization of cotton pickers. Also, it is indicated that PVD-TiN coating can effectively improve the wear resistance of the spindle surface and provides a new method for enhancing the service life of the spindle. Full article
(This article belongs to the Section Tribology)
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65 pages, 13363 KiB  
Review
Joining Technologies for Aluminium Castings—A Review
by Dezhi Li, Carl Slater, Huisheng Cai, Xiaonan Hou, Yongbing Li and Qudong Wang
Coatings 2023, 13(5), 958; https://doi.org/10.3390/coatings13050958 - 19 May 2023
Cited by 3 | Viewed by 3275
Abstract
Aluminium castings have been widely used in many industries, including automotive, aerospace, telecommunication, construction, consumer products, etc., due to their lightweight, good electric and thermal conductivity, and electromagnetic interference/radio frequency interference (EMI/RFI) shielding properties. The main applications of aluminium castings are in automotive [...] Read more.
Aluminium castings have been widely used in many industries, including automotive, aerospace, telecommunication, construction, consumer products, etc., due to their lightweight, good electric and thermal conductivity, and electromagnetic interference/radio frequency interference (EMI/RFI) shielding properties. The main applications of aluminium castings are in automotive industry. For lighweighting purposes, more and more aluminium castings are used in the automotive vehicle structures to reduce weight, improve fuel efficiency, and reduce greenhouse gas emissions. However, due to the features of cast aluminium, such as porosity, poor surface quality, a tendency toward hot cracking, and low ductility, joining these materials is problematic. In this paper, the joining technologies for aluminium castings and the related issues, mainly cracking and porosity, are reviewed. The current state-of-the-art of joining technologies is summarized, and areas for future research are recommended. Full article
(This article belongs to the Special Issue Recent Developments in Advanced Manufacturing Technology)
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13 pages, 9053 KiB  
Article
Effect of Post-Oxidation Treatment on the Performance and Microstructure of Silicon Carbide Ceramic Membrane
by Liqun Hu, Yue Hu, Jiaying Zhu, Jin Li, Pinhua Rao, Jian Guo, Guanghui Li and Jinjie Wang
Coatings 2023, 13(5), 957; https://doi.org/10.3390/coatings13050957 - 19 May 2023
Cited by 2 | Viewed by 1171
Abstract
The post-oxidation treatment (POT) is an important step in the preparation of silicon carbide (SiC) ceramic membranes via recrystallization sintering, which is generally considered to remove any possible free carbon. It is found, however, that increasing the temperature of POT improves not only [...] Read more.
The post-oxidation treatment (POT) is an important step in the preparation of silicon carbide (SiC) ceramic membranes via recrystallization sintering, which is generally considered to remove any possible free carbon. It is found, however, that increasing the temperature of POT improves not only the hydrophilicity and flux of SiC ceramic membranes but also their mechanical properties, chemical stability, etc. Therefore, it is necessary to study the principle of POT in order to obtain SiC ceramic membranes with optimal properties. In this study, the principle of POT was characterized via scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, synchronous thermal analysis, and metallographic microscopy. According to the principle, the conditions, such as the temperature and air flow rate, of the post-oxidation process were optimized. Under the optimized conditions, POT improved the flux of SiC ceramic membranes from 1074 to 5118 L·m−2·h−1·bar−1, increased the bending strength from 26 to 35 MPa, and provided SiC ceramic membranes with high stability under acid and alkali conditions. Full article
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13 pages, 3247 KiB  
Article
Mechanical and Tribological Behaviors of Hot-Pressed SiC/SiCw-Y2O3 Ceramics with Different Y2O3 Contents
by Shaohua Zhang, Jinfang Wang, Meng Zhang, Longqi Ding, Huijun Chan, Xiyu Liu, Fengqing Wu, Zhibiao Tu, Ling Shao, Nengyong Ye, Sheng Dai, Liu Zhu and Shichang Chen
Coatings 2023, 13(5), 956; https://doi.org/10.3390/coatings13050956 - 19 May 2023
Cited by 1 | Viewed by 1100
Abstract
Sintering additives are commonly used to reduce the conditions required for densification in composite ceramics without compromising their performances simultaneously. Herein, SiC/SiCw-Y2O3 composite ceramics with 10 vol.% SiC whiskers (SiCw) and different Y2O3 [...] Read more.
Sintering additives are commonly used to reduce the conditions required for densification in composite ceramics without compromising their performances simultaneously. Herein, SiC/SiCw-Y2O3 composite ceramics with 10 vol.% SiC whiskers (SiCw) and different Y2O3 contents (0, 2.5, 5, 7.5, and 10 vol.%) were fabricated by hot-pressed sintering at 1800 °C, and the effects of Y2O3 content on the microstructure, mechanical properties, and tribological behaviors were investigated. It was found that the increased Y2O3 content can promote the densification of SiC/SiCw-Y2O3 composite ceramics, as evidenced by compact microstructure and increased relative density. The Vickers hardness, fracture toughness, and flexural strength also increased when Y2O3 content increased from 2.5 vol.% to 7.5 vol.%. However, excessive Y2O3 (10 vol.%) aggregated around SiC and SiCw weakens its positive effect. Furthermore, the Y2O3 additive also reduces the coefficient of friction (COF) of SiC/SiCw-Y2O3 composite ceramics, the higher the Y2O3 content, the lower the COF. The wear resistance of SiC/SiCw-Y2O3 composite ceramics is strongly affected by their microstructure and mechanical properties, and as-sintered SiC ceramic with 7.5 vol.% Y2O3 (Y075) shows the optimal wear resistance. The relative density, Vickers hardness, fracture toughness, and flexural strength of Y075 are 97.0%, 21.6 GPa, 7.7 MPa · m1/2, and 573.2 MPa, respectively, the specific wear rate of Y075 is 11.8% of that for its competitor with 2.5 vol.% Y2O3. Full article
(This article belongs to the Special Issue Advances of Ceramic and Alloy Coatings)
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21 pages, 8435 KiB  
Article
Influence of Co-Content on the Optical and Structural Properties of TiOx Thin Films Prepared by Gas Impulse Magnetron Sputtering
by Patrycja Pokora, Damian Wojcieszak, Piotr Mazur, Małgorzata Kalisz and Malwina Sikora
Coatings 2023, 13(5), 955; https://doi.org/10.3390/coatings13050955 - 19 May 2023
Cited by 2 | Viewed by 1048
Abstract
Nonstoichiometric (Ti,Co)Ox coatings were prepared using gas-impulse magnetron sputtering (GIMS). The properties of coatings with 3 at.%, 19 at.%, 44 at.%, and 60 at.% Co content were compared to those of TiOx and CoOx films. Structural studies with the aid of [...] Read more.
Nonstoichiometric (Ti,Co)Ox coatings were prepared using gas-impulse magnetron sputtering (GIMS). The properties of coatings with 3 at.%, 19 at.%, 44 at.%, and 60 at.% Co content were compared to those of TiOx and CoOx films. Structural studies with the aid of GIXRD indicated the amorphous nature of (Ti,Co)Ox. The fine-columnar, homogeneous microstructure was observed on SEM images, where cracks were identified only for films with a high Co content. On the basis of XPS measurements, TiO2, CoO, and Co3O4 forms were found on their surface. Optical studies showed that these films were semi-transparent (T > 46%), and that the amount of cobalt in the film had a significant impact on the decrease in the transparency level. A shift in the absorption edge position (from 337 to 387 nm) and a decrease in their optical bandgap energy (from 3.02 eV to more than 2.60 eV) were observed. The hardness of the prepared films changed slightly (ca. 6.5 GPa), but only the CoOx film showed a slightly lower hardness value than the rest of the coatings (4.8 GPa). The described studies allowed partial classification of non-stoichiometric (Ti,Co)Ox thin-film materials according to their functionality. Full article
(This article belongs to the Special Issue Advances in Thin Film Fabrication by Magnetron Sputtering)
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15 pages, 8013 KiB  
Article
Facile Fabrication of Robust and Fluorine-Free Superhydrophobic PDMS/STA-Coated Cotton Fabric for Highly Efficient Oil-Water Separation
by Daibin Tang and Enzhou Liu
Coatings 2023, 13(5), 954; https://doi.org/10.3390/coatings13050954 - 19 May 2023
Cited by 5 | Viewed by 1389
Abstract
Oil–water separation using special wettability materials has received much attention due to its low energy consumption and high separation efficiency. Herein, a fluorine-free superhydrophobic cotton fabric (PDMS/STA-coated cotton fabric) was successfully prepared by a simple impregnation method using hydroxyl-capped polydimethylsiloxane (PDMS-OH), tetraethoxysilane (TEOS), [...] Read more.
Oil–water separation using special wettability materials has received much attention due to its low energy consumption and high separation efficiency. Herein, a fluorine-free superhydrophobic cotton fabric (PDMS/STA-coated cotton fabric) was successfully prepared by a simple impregnation method using hydroxyl-capped polydimethylsiloxane (PDMS-OH), tetraethoxysilane (TEOS), and stearic acid (STA) as precursors. The investigation found that the cross-linking reactions between the hydroxyl groups of PDMS-OH and hydrolyzed TEOS enabled a strong interaction between PDMS-OH and cotton fabric. Furthermore, a suitable roughness surface of coated cotton fabric was established by introducing STA due to its long chain structure. The contact angle of this composite can reach 158.7° under optimal conditions due to its low surface energy and desired roughness. The oil/water separation efficiency of PDMS/STA-coated cotton fabric is higher than 90% even after 10 cycles of oil–water separation, and the oil flux can reach 11862.42 L m−2 h−1. In addition, PDMS/STA-coated cotton fabric exhibits excellent chemical stability and durability under extreme conditions such as strong acid (HCl, pH = 1~2) and alkali (NaOH, pH = 13~14), and the hydrophobicity of PDMS/STA-coated cotton fabric was decreased to 147° after 300 cycles of abrasion testing. Full article
(This article belongs to the Special Issue Sustainable Coatings for Functional Textile and Packaging Materials)
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26 pages, 11891 KiB  
Article
The Electrodeposition of Derivatives of Pyrrole and Thiophene on Brass Alloy in the Presence of Dodecane-1-Sulfonic Acid Sodium Salt in Acidic Medium and Its Anti-Corrosive Properties
by Florina Branzoi and Simona Petrescu
Coatings 2023, 13(5), 953; https://doi.org/10.3390/coatings13050953 - 19 May 2023
Cited by 1 | Viewed by 1050
Abstract
In this paper, potentiostatic and galvanostatic deposition (electrochemical deposition) processes have been used for the obtained of a new composite polymer: N-methylpyrrole-sodium 1-dodecanesulfonate/poly 2-methylthiophene (PNMPY-1SSD/P2MT) coatings over brass electrode for corrosion protection. The sodium 1-dodecanesulfonate as a dopant ion employed in the electropolymerization [...] Read more.
In this paper, potentiostatic and galvanostatic deposition (electrochemical deposition) processes have been used for the obtained of a new composite polymer: N-methylpyrrole-sodium 1-dodecanesulfonate/poly 2-methylthiophene (PNMPY-1SSD/P2MT) coatings over brass electrode for corrosion protection. The sodium 1-dodecanesulfonate as a dopant ion employed in the electropolymerization procedure can have a meaningful effect on the anti-corrosion protection of the composite polymeric film by stopping the penetration of corrosive ions. The composite coatings have been characterized by cyclic voltammetry, Fourier transform infrared (FT-IR) spectroscopy, and scanning electron microscopy (SEM) procedures. The anti-corrosion performance of PNMPY-1SSD/P2MT coated brass has been investigated by potentiostatic and potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) practices in 0.5 M H2SO4 medium. The corrosion assessment of PNMPY-1SSD/P2MT coated brass was noticed to be ~9 times diminished than of uncoated brass, and the efficiency of these protective coatings of this coating is above 90%. The highest effectiveness is realized by the electrochemical deposition of PNMPY-1SSD/P2MT obtained at 1.1 V and 1.4 V potential applied and at 0.5 mA/cm2 and 1 mA/cm2 current densities applied in molar ratio 5:3. The outcomes of the corrosion tests denoted that PNMPY-1SSD/P2MT coatings assure good anti-corrosion protection of brass in corrosive media. Full article
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13 pages, 6633 KiB  
Article
Morphology and Composition of the Third Body on the Friction Surface of an Organic Composite Railway Brake Shoe
by Chunjiang He, Yuan Ji, Dingfeng Pei, Ming Gao, Chuanzhi Chen, Jingcun Zhao and Wei Wang
Coatings 2023, 13(5), 952; https://doi.org/10.3390/coatings13050952 - 19 May 2023
Viewed by 1238
Abstract
Friction properties are significantly affected by third bodies (films formed on friction surfaces). However, the study of their composition and structure remains incomplete. For this reason, an organic composite railway brake shoe was tested at an initial braking speed of 125 km/h using [...] Read more.
Friction properties are significantly affected by third bodies (films formed on friction surfaces). However, the study of their composition and structure remains incomplete. For this reason, an organic composite railway brake shoe was tested at an initial braking speed of 125 km/h using a full-scale dynamometer. A third body with a thickness of ~120 μm was obtained, and its morphology and composition were analyzed using a multiple techniques. The results indicated that the third body had a layered structure. The upper surface was smoother than the lower surface. The carbon content on the upper surface decreased by 68.01%, and the iron content increased by 11.85 times in relation to that on the lower surface. Compared to the brake shoe, the iron content of the third body increased by 272.81%, and most of the iron was oxidized. Furthermore, the content of barium, calcium, and silicon decreased by more than 33%, and the crystalline structures of the inorganic filler materials, such as graphite and barium sulfate, were destroyed, with new crystalline structures appearing. Finally, the residual weight at 650 °C increased from 90.35% to 96.59%. This research could provide a reference for exploring the friction and wear mechanisms of organic composite railway brake shoes. Full article
(This article belongs to the Special Issue Friction, Wear, Lubrication and Mechanics of Surfaces and Interfaces)
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13 pages, 5486 KiB  
Article
Fabrication and Characterization of Ti/TiC Composite Layers by an Electron-Beam Surface Modification
by Stefan Valkov, Daniela Nedeva, Vladimir Dunchev, Fatme Padikova, Maria Ormanova, Borislav Stoyanov and Nikolay Nedyalkov
Coatings 2023, 13(5), 951; https://doi.org/10.3390/coatings13050951 - 19 May 2023
Cited by 1 | Viewed by 1370
Abstract
In this study, the possibilities for modification and improvement of the surface structure and properties of titanium substrates by a formation of composite Ti/TiC layers are presented. The layers were fabricated by a two-step electron-beam surface modification technique. The first step consists of [...] Read more.
In this study, the possibilities for modification and improvement of the surface structure and properties of titanium substrates by a formation of composite Ti/TiC layers are presented. The layers were fabricated by a two-step electron-beam surface modification technique. The first step consists of injection of C powder within the pure Ti substrates by electron-beam alloying technology. The second step is the refinement and homogenization of the microstructure by the electron-beam remelting procedure. During the remelting, the speed of the motion of the samples was varied, and two (most representative) velocities were chosen: 5 and 15 mm/s. Considering both speeds of the motion of the specimens, a composite structure in the form of fine TiC particles distributed within the base titanium matrix was formed. The remelting speed of 5 mm/s led to the formation of a much thicker composite layer, where the TiC particles were significantly more homogeneously distributed. The results obtained for the Vickers microhardness exhibit a significant increase in the value in the mentioned mechanical characteristic in comparison with the base Ti substrate. In the case of the lower speed of the motion of the specimen during the remelting procedure, the microhardness is 510 HV, or about 2.5 times higher than that of the titanium substrate. The application of a higher speed of the specimen motion leads to a decrease in the microhardness in comparison with the case of lower velocity. However, it is still much higher than that of the base Ti material. The mean microhardness of the sample obtained by the remelting speed of motion of 15 mm/s is 360 HV, or it is 1.8 times higher than that of the base material. Full article
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10 pages, 2019 KiB  
Communication
High-Frequency Conductivity of Amorphous and Crystalline Sb2Te3 Thin Films
by Rene Castro, Aleksei Kononov and Nadezhda Anisimova
Coatings 2023, 13(5), 950; https://doi.org/10.3390/coatings13050950 - 18 May 2023
Viewed by 788
Abstract
The results of study of charge transfer processes in thin amorphous and crystalline Sb2Te3 films in a wide range of frequencies and temperatures are presented. The frequency spectra of conductivity were obtained by the dielectric spectroscopy method. The authors analyzed [...] Read more.
The results of study of charge transfer processes in thin amorphous and crystalline Sb2Te3 films in a wide range of frequencies and temperatures are presented. The frequency spectra of conductivity were obtained by the dielectric spectroscopy method. The authors analyzed the frequency dependences of the conductivity in the electric field and the temperature dependences of the exponent s. A transition from the classical correlated barrier hopping (CBH) to quantum mechanical tunneling (QMT) was observed at a certain temperature Tt. The CBH model allowed the authors to calculate the conductivity parameters of two phases. Two areas with different types of conductivity were revealed on the conduction spectra, and the activation energies of charge transfer processes for amorphous and crystalline films were determined. The following features were discovered: the difference in the temperatures of the change of the charge transfer mechanism and the transition from the semiconductor region to the metal region on the temperature dependence of conductivity. They can help to identify the amorphous phase in the quasi-binary chalcogenide Sb2Te3-GeTe system. Full article
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17 pages, 17741 KiB  
Article
Investigation of the Microstructure and Wear Properties of Conventional Laser Cladding and Ultra-High-Speed Laser Cladding Alloy Coatings for Wheel Materials
by Qian Xiao, Jinlong Xia, Xueshan Gao, Wenbin Yang, Daoyun Chen, Haohao Ding and Yao Wang
Coatings 2023, 13(5), 949; https://doi.org/10.3390/coatings13050949 - 18 May 2023
Cited by 1 | Viewed by 1324
Abstract
In this paper, Fe-based and Co-based alloy powders were chosen to perform laser cladding on wheel materials through conventional laser cladding (CLC) and ultra-high-speed laser cladding (UHSLC) processes, respectively. The microstructures, element distribution, phase composition and hardness of the Fe-based alloy and Co-based [...] Read more.
In this paper, Fe-based and Co-based alloy powders were chosen to perform laser cladding on wheel materials through conventional laser cladding (CLC) and ultra-high-speed laser cladding (UHSLC) processes, respectively. The microstructures, element distribution, phase composition and hardness of the Fe-based alloy and Co-based alloy coating layers using the CLC and UHSLC processes were compared and analysed. The results show that the CLC and UHSLC alloy coatings were dense and free of defects such as pores and cracks. Compared with the CLC alloy coating, the grain size of the UHSLC alloy coating was smaller, the coating composition was close to the powder design composition, and the distribution of Cr within and between the grains was more uniform. The Fe-based coating was mainly composed of (Fe, Ni) and Cr7C3, and the Co-based coating was mainly composed of γ-Co and Cr23C6. It was found that the cooling rate of the CLC alloy coating was smaller than that of the USHLC, and the hardness of the CLC alloy coating was less than that of the USHLC. The average hardness of the UHSLC Fe-based and Co-based alloy coatings was 709 HV and 525 HV, respectively. The average hardness of the CLC Fe-based and Co-based alloy coatings was 615 HV and 493 HV, respectively. The rolling friction and wear tests were carried out with the CLC-treated and UHSLC-treated wheel specimens on the GPM-30 rolling contact fatigue testing machine. The results showed that the wear rate of the UHSLC alloy coating on the wheel specimens was significantly lower than that of the CLC alloy coating on the wheel specimens. The wear rates of the UHSLC Fe-based and Co-based alloy coatings on the wheel specimens were reduced by 40.7% and 73.8%, respectively. It was demonstrated that the wear resistance of the USHLC alloy coatings was better than those of the CLC alloy coatings. The CLC alloy coating exhibited more severe fatigue damage with small cracks. Furthermore, the damage of the UHSLC alloy coating was relatively minor, with slight spalling. The Co-based alloy coating exhibited superior wear properties with the same laser cladding process. Full article
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12 pages, 14874 KiB  
Communication
Effect of Ball-Milled Feedstock Powder on Microstructure and Mechanical Properties of Cu-Ni-Al-Al2O3 Composite Coatings by Cold Spraying
by Hongjin Liu, Mingkun Fu, Shaozhi Pang, Huaiqing Zhu, Chen Zhang, Lijun Ming, Xinyu Liu, Minghui Ding and Yudong Fu
Coatings 2023, 13(5), 948; https://doi.org/10.3390/coatings13050948 - 18 May 2023
Cited by 2 | Viewed by 1157
Abstract
Cu, Ni and Al powders mixed in a certain stoichiometric proportion were ground via ball milling and deposited as coatings using low pressure cold spraying (LPCS) technology. The effect of particle morphology on the powder structure as well as the microstructure, composition and [...] Read more.
Cu, Ni and Al powders mixed in a certain stoichiometric proportion were ground via ball milling and deposited as coatings using low pressure cold spraying (LPCS) technology. The effect of particle morphology on the powder structure as well as the microstructure, composition and mechanical properties of the coatings was studied. The results revealed a core–shell structure of ball-milled powders. Compared with a mechanically mixed (MM) coating, coatings after ball milling at a rotation speed of 200 rpm exhibited the most uniform composition distribution and a lower degree of porosity (by 0.29%). Moreover, ball milling at 200 rpm was conducive to a significant increase in the deposition efficiency of the sprayed powder (by 10.89%), thereby improving the microhardness distribution uniformity. The ball milling treatment improved the adhesion of the coatings, and the adhesion of the composite coating increased to 40.29 MPa with the increase in ball milling speed. The dry sliding wear tests indicated that ball milling treatment of sprayed powder significantly improved the wear properties of the coatings. The coating after ball milling at a speed of 250 rpm showed the lowest friction coefficient and wear rate, with values of 0.41 and 2.47 × 10−12 m3/m, respectively. The wear mechanism of coatings changed from abrasive wear to adhesive wear with the increase in ball milling speed. Full article
(This article belongs to the Special Issue Advanced Cold Spraying Technology)
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9 pages, 4520 KiB  
Article
NbSe2 Crystals Growth by Bromine Transport
by Dimitre Dimitrov, Peter Rafailov, Vera Marinova, Ivalina Avramova, Daniela Kovacheva, Irnik Dionisiev, Nikolay Minev and Marin Gospodinov
Coatings 2023, 13(5), 947; https://doi.org/10.3390/coatings13050947 - 18 May 2023
Viewed by 1723
Abstract
Recently, low-dimensional structures in the form of bulk crystals and nanoflakes have received considerable interest due to their 2D unique functionality and promising applications in electronics, photonics, sensing devices and photovoltaic solar cells. As a result, remarkable efforts and modifications have been made [...] Read more.
Recently, low-dimensional structures in the form of bulk crystals and nanoflakes have received considerable interest due to their 2D unique functionality and promising applications in electronics, photonics, sensing devices and photovoltaic solar cells. As a result, remarkable efforts and modifications have been made for the synthesis process of crystalline material by the vapor transport technique. Here, an alternative concept of NbSe2 crystal growth by the chemical vapor transport (CVT) technique using bromine as a vapor transport agent is presented and subsequently analyzed by X-ray diffraction (XRD), Raman and X-ray photoelectron spectroscopy (XPS) spectroscopy. X-ray powder diffraction analysis revealed hexagonal 2H-NbSe2 and 4H-NbSe2 phases, and characteristic Raman and XPS spectra typical for crystalline NbSe2 were obtained. The environmental sensitivity of the grown crystals is manifested by luminescence attributed to oxidized Nb at the samples’ surface. Full article
(This article belongs to the Special Issue Application of Graphene and Two-Dimensional Materials in Thin Films)
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14 pages, 7137 KiB  
Article
The Influence of Iron Tailings Powder on the Properties on the Performances of Cement Concrete with Machine-Made Sand
by Lin Wang, Genkun Du, Xinxin He, Zicheng Wei, Yubo Xu, Shuai Li and Xuejuan Liu
Coatings 2023, 13(5), 946; https://doi.org/10.3390/coatings13050946 - 18 May 2023
Viewed by 1175
Abstract
Iron tailings powder (ITP) is a kind of solid waste, which pollutes the environment, without any treatment. The application of ITP in cement concrete is a good choice. In this study, the influence of ITP on the flowability, compressive strength, chloride ion permeability [...] Read more.
Iron tailings powder (ITP) is a kind of solid waste, which pollutes the environment, without any treatment. The application of ITP in cement concrete is a good choice. In this study, the influence of ITP on the flowability, compressive strength, chloride ion permeability and the attenuation of the performance of cement concrete during freeze–thaw cycle (F-T) damage are investigated. An X-ray diffraction, an analysis of the pores and a scanning electron microscope (SEM) are obtained to analyze the mechanism of cement concrete’s performance. The results show that the addition of ITP can decrease the flowability of fresh cement concrete. Cement concrete with a 7% ITP to mass ratio of the total aggregate shows the highest compressive strength and the minimum chloride ion permeability. The relative dynamic modulus of the elasticity of the specimens with 7% ITP during the F-T is the highest. The corresponding mass loss rate is the lowest. The mercury intrusion analysis results show that the pore volume of the specimens with 7% ITP is the lowest. The SEM results confirm that the specimens with 7% ITP show the densest microstructures. Full article
(This article belongs to the Special Issue Surface Modified Repairing Materials and Mechanics)
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1 pages, 154 KiB  
Correction
Correction: Tong et al. Effect of Micro-Textures on the Surface Interaction of WC+Co Alloy Composite Coatings. Coatings 2022, 12, 1242
by Xin Tong, Yu Zhang and Xiaoyang Yu
Coatings 2023, 13(5), 945; https://doi.org/10.3390/coatings13050945 - 18 May 2023
Cited by 1 | Viewed by 579
Abstract
Affiliation Correction [...] Full article
19 pages, 4967 KiB  
Article
Effect of Redox Switch, Coupling, and Continuous Polarization on the Anti-Corrosion Properties of PEDOT Film in NaCl Solution
by Victor Malachy Udowo, Maocheng Yan, Fuchun Liu and En-Hou Han
Coatings 2023, 13(5), 944; https://doi.org/10.3390/coatings13050944 - 17 May 2023
Cited by 4 | Viewed by 1229
Abstract
Conjugated poly(3,4-ethylenedioxythiophene) (PEDOT) film was electrochemically synthesized on stainless steel (SS). Redox interactions between the PEDOT film and the SS substrate were examined in 3.5 wt.% NaCl aqueous solution with the aid of electrochemical and spectroscopic analyses. The results show that the PEDOT [...] Read more.
Conjugated poly(3,4-ethylenedioxythiophene) (PEDOT) film was electrochemically synthesized on stainless steel (SS). Redox interactions between the PEDOT film and the SS substrate were examined in 3.5 wt.% NaCl aqueous solution with the aid of electrochemical and spectroscopic analyses. The results show that the PEDOT film exhibited a barrier effect and mediated the oxygen reduction reaction, thus hindering ion diffusion to the steel substrate. Localized electrochemical impedance spectroscopy (LEIS) of the scratched area on the polymer film shows that PEDOT healed the defect by coupling with redox reactions on the steel surface to prevent charge localization and concentration. The electroactivity of the polymer film declined when PEDOT was polarized at potentials >−0.7 V. Prolonged exposure of the PEDOT film to dissolved oxygen in NaCl solution resulted in the polymer’s over-oxidation (degradation), evidenced by the formation of a carbonyl group in the spectroscopic result. The degradation of PEDOT was attributed to chain scissoring due to hydroxide ion attacks on the polymer chain. Full article
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21 pages, 5625 KiB  
Article
Evaluation of Galvanic and Crevice Corrosion of Watch Case Middle (1.4435 Steel) and Bottom (Panacea® Steel) Assembly Supposed to Be in Prolonged Contact with the Skin
by Lucien Reclaru, Cosmin M. Cotrut, Diana M. Vranceanu and Florina Ionescu
Coatings 2023, 13(5), 943; https://doi.org/10.3390/coatings13050943 - 17 May 2023
Viewed by 1056
Abstract
Today, laws protecting the population at the global level aim to minimize the induction risk of allergies to type IV contact dermatitis. In the European population, the prevalence of nickel allergy is at 10%–15% of adult females and 1%–3% of adult males. A [...] Read more.
Today, laws protecting the population at the global level aim to minimize the induction risk of allergies to type IV contact dermatitis. In the European population, the prevalence of nickel allergy is at 10%–15% of adult females and 1%–3% of adult males. A total of 30% of nickel-sensitive people in the general population develop hand eczema. This study concerns the possibility of assembling a bottom of nickel-free austenitic steel (Panacea®) in a watch case middle made of a grade of austenitic steels, steel 316L (DIN 1.44359), to avoid the risks of Ni release and to develop a galvanic pile between these two dissimilar materials. Two types of methods were used: direct measurements and prediction techniques (mixed potentials theory). For the degradation of thbottom-middle watch assembly, Nielsen–Tuccillo tests were performed, and Ni release measurements according to EN 1811 completed the study. All direct electrochemical investigations and galvanic current prediction measurements show low current values of 40–400 nA. Measurements of nickel release of Panacea® and 316L reveal small quantities of nickel, much lower than the 0.5 µg/cm2 per week that the European legislation enforces. The nickel-free steel Panacea® in the work hardening conditions 280, 427, and 510 HV0.1s were also studied. The cation extractions reveal the large quantities released from Cr, Mo, Mn, and Fe, so there is a risk of toxicity in contact with the skin. Full article
(This article belongs to the Special Issue Anti-corrosion Coatings of Metals and Alloys – New Perspectives)
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8 pages, 11708 KiB  
Article
Surface Smoothing by Gas Cluster Ion Beam Using Decreasing Three-Step Energy Treatment
by Vasiliy Pelenovich, Xiaomei Zeng, Xiangyu Zhang, Dejun Fu, Yan Lei, Bing Yang and Alexander Tolstoguzov
Coatings 2023, 13(5), 942; https://doi.org/10.3390/coatings13050942 - 17 May 2023
Cited by 2 | Viewed by 1046
Abstract
A three-step treatment of Si wafers by gas cluster ion beam with decreasing energy was used to improve the performance of surface smoothing. First, a high energy treatment at 15 keV and an ion fluence of 2 × 1016 cm−2 was [...] Read more.
A three-step treatment of Si wafers by gas cluster ion beam with decreasing energy was used to improve the performance of surface smoothing. First, a high energy treatment at 15 keV and an ion fluence of 2 × 1016 cm−2 was used to remove initial surface features (scratches). Next, treatments at 8 and 5 keV with the same fluences reduced the roughness that arose due to the formation of morphological features induced by the surface sputtering at the first high energy step. The surface morphology was characterized by the atomic force microscopy. The root mean square roughness Rq and 2D isotropic power spectral density functions were analyzed. For comparison, the smoothing performances of single-step treatments at 15, 8, and 5 keV were also studied. The lowest roughness values achieved for the single and three-step treatments were 1.06 and 0.65 nm, respectively. Full article
(This article belongs to the Special Issue Recent Advances in Surface Functionalisation)
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