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Volume 14
Issue 8
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Coatings, Volume 14, Issue 8 (August 2024) – 159 articles

Cover Story (view full-size image): Two-dimensional materials with ultrathin structures are characterized by water impermeability, a high specific surface area, and excellent mechanical properties, qualities that prove promising for their wide application. The layered ultrathin structure of pigments from a group of transition metal dichalcogenides (MoS2 and WS2), layered with transition metal oxides (MoO3 and WO3) and other semiconductor materials (ZnS and ZnO), was used to provide an enhanced mechanical and anticorrosion performance of pigmented systems containing spherical zinc. The results of our experiments showed an increase in both mechanical and anticorrosion performance when using these special types of inorganic pigments and an enhancement in the individual types of action mechanisms typical and proven for zinc-pigmented systems. View this paper
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15 pages, 3558 KiB  
Article
Comprehensive Analysis of Fullerene- and Non-Fullerene-Based Bulk Heterojunction Solar Cells Using Numerical Simulation
by Muhammad Raheel Khan and Bożena Jarząbek
Coatings 2024, 14(8), 1078; https://doi.org/10.3390/coatings14081078 - 22 Aug 2024
Viewed by 976
Abstract
In recent years, two-dimensional (2D) materials have been widely used for various applications due to their low cost, high charge carrier mobility, and tunable electronic structure. Here, in this study, we present the application of molybdenum disulfide (MoS2) used as a [...] Read more.
In recent years, two-dimensional (2D) materials have been widely used for various applications due to their low cost, high charge carrier mobility, and tunable electronic structure. Here, in this study, we present the application of molybdenum disulfide (MoS2) used as a hole transport layer (HTL) material for fullerene (FA) and non-fullerene (NFA)-based organic photovoltaic (OPV) devices. A numerical simulation is carried out for these types of solar cells, and the SCAPS-1D software tool is used. Our study is specifically focused on the impact of thickness, the optimization of interface engineering, and the effect of high-temperature analysis to improve the output characteristics. The influence of interface defects between the HTL/active layer and the active layer/ETL (electron transport layer) is also contemplated. After optimization, the obtained power conversion efficiency (PCE) of these NFA- and FA-based devices is reported as 16.38% and 9.36%, respectively. A reflection coating study is also carried out to improve the power conversion efficiency of these devices. Here, the presented results demonstrate that molybdenum disulfide (MoS2) as a 2D material can be successfully used as an HTL material for high-efficiency OPV devices, both for fullerene (FA)- and non-fullerene (NFA)-based solar cells. Full article
(This article belongs to the Special Issue Energy Storage and Conversion: From Materials, Devices to Applications)
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14 pages, 4991 KiB  
Article
The Evolution of Surfaces on Medium-Carbon Steel for Fatigue Life Estimations
by Phanuphak Seensattayawong and Eberhard Kerscher
Coatings 2024, 14(8), 1077; https://doi.org/10.3390/coatings14081077 - 22 Aug 2024
Viewed by 810
Abstract
Early in fatigue life, fatigue cracks are often initiated at persistent slip bands (PSBs), which play the main role in surface evolution when the components are subjected to cyclic loading. Therefore, this paper aims to study the behavior of the surface development of [...] Read more.
Early in fatigue life, fatigue cracks are often initiated at persistent slip bands (PSBs), which play the main role in surface evolution when the components are subjected to cyclic loading. Therefore, this paper aims to study the behavior of the surface development of medium-carbon steel, specifically 42CrMo4 (SAE 4140). Tests were conducted using tension–compression fatigue testing with stress amplitudes set at 30%, 40%, and 50% of the ultimate tensile strength (UTS); a load ratio of R = −1; and a frequency of f = 10 Hz. The ultimate number of test cycles was 2 × 105. The fatigue test specimens with as-machined surface quality (Ra < 100 nm) were tested on a servo-hydraulic push–pull testing machine, and the tests were interrupted a few times to bring the specimens out for surface measuring with a confocal microscope. The linear roughness values of the arithmetic mean deviation (Ra), maximum height (Rz), maximum profile peak height (Rp), and maximum profile valley depth (Rv) were investigated and further used to determine the roughness evolution during cyclic loading (REC) by analyzing the inclinations of the fitting curves of roughness and number-of-cycles diagrams. REC could then be used to estimate and classify the fatigue lifetime. Full article
(This article belongs to the Special Issue Microstructure, Fatigue and Wear Properties of Steels, 2nd Edition)
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18 pages, 7916 KiB  
Article
Effect of Bushing Structure on Mechanical Properties and Failure Mechanism of CFRP Laminated Titanium Nail Riveting
by Deyi Wang, Yichun Zhu, Bo Wang, Mingli Xiang and Chengzhi Song
Coatings 2024, 14(8), 1076; https://doi.org/10.3390/coatings14081076 - 22 Aug 2024
Viewed by 679
Abstract
In the aerospace field, the riveting process is one of the main methods for connecting the Carbon Fiber Reinforced Polymer/Plastic (CFRP). During the riveting process, components are prone to problems such as damage to CFRP hole walls and reduction in joint strength. To [...] Read more.
In the aerospace field, the riveting process is one of the main methods for connecting the Carbon Fiber Reinforced Polymer/Plastic (CFRP). During the riveting process, components are prone to problems such as damage to CFRP hole walls and reduction in joint strength. To this end, this paper proposes two new bushing structures based on riveting. The riveting damage behavior and mechanical properties of composite materials under three riveting methods: non-bushing, non-boss bushing, and boss bushing were compared. Furthermore, the tensile and hysteretic mechanical properties of CFRP under different riveting structures were studied. The results show that the stress distribution around the hole is more uniform than that of the non-bushing riveting method, and the delamination damage at the hole wall is significantly reduced. In the tensile test, the maximum tensile loads of the non-boss bushing and the boss bushing increased by 2.49% and 5.03% compared to the non-boss bushing schemes. In addition, the tensile failure modes of the three schemes also showed different failure modes due to different riveting forms. The failure mode of the non-bushing riveting scheme is rivet shear failure, and the failure mode of the bushing riveting scheme is rivet pull-off failure. In the hysteretic test, the maximum tensile loads of the non-boss bushing and the boss bushing increased by 5.49% and 12.03% compared to the non-bushing scheme. The failure mode of the three schemes is rivet pull-off failure. The bushing structure not only enhances the connection strength, but also improves the damage to the CFRP hole wall. This study provides a new understanding of the design and optimization of CFRP riveted connection structures. Full article
(This article belongs to the Special Issue Recent Developments in Interfaces and Surfaces Engineering)
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15 pages, 7964 KiB  
Article
Nanoindentation Study on the Local Evaluation of Hydrogen-Induced Hardening Performance of Ferrite and Austenite in 2205 Duplex Stainless Steel: Experiment and Finite Element Modeling
by Ping Tao, Wei Zhou, Hongmei Liu and Xuedong Liu
Coatings 2024, 14(8), 1075; https://doi.org/10.3390/coatings14081075 - 22 Aug 2024
Viewed by 879
Abstract
In this study, a combined experimental and finite element modeling methodology (FEM) for a nanoindentation study is presented to quantitatively investigate the influence of hydrogen on the mechanical properties of ferrite and austenite in 2205 duplex stainless steel. The experimental results showed that, [...] Read more.
In this study, a combined experimental and finite element modeling methodology (FEM) for a nanoindentation study is presented to quantitatively investigate the influence of hydrogen on the mechanical properties of ferrite and austenite in 2205 duplex stainless steel. The experimental results showed that, during hydrogen charging, the nano-hardness of ferrite and austenite gradually increased with time, showing a hydrogen-induced hardening phenomenon. After 3 h of hydrogen charging, the nano-hardness of both ferrite and austenite reached a saturation state, and the values of the nano-hardness of ferrite and austenite increased by 17.5% and 46.1%, respectively. FEM is employed by using a dual-phase microstructure-based model to reproduce nanoindentation load–displacement curves. To minimize the indentation size effect, an analytical correction model considering geometrically necessary dislocations (GNDs) was proposed. By considering GNDs, the errors between numerical predictions and experimental data reduced from about 50% to less than 5%. Full article
(This article belongs to the Special Issue Microstructure, Fatigue and Wear Properties of Steels, 2nd Edition)
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19 pages, 10547 KiB  
Article
Bimetallic Ni–Mn Electrocatalysts for Stable Oxygen Evolution Reaction in Simulated/Alkaline Seawater and Overall Performance in the Splitting of Alkaline Seawater
by Sukomol Barua, Aldona Balčiūnaitė, Daina Upskuvienė, Jūrate Vaičiūnienė, Loreta Tamašauskaitė-Tamašiūnaitė and Eugenijus Norkus
Coatings 2024, 14(8), 1074; https://doi.org/10.3390/coatings14081074 - 22 Aug 2024
Viewed by 1336
Abstract
The perfect strategy for the generation of green and renewable hydrogen (H2) fuels is the direct electrocatalytic splitting of plentiful seawater rather than scarce freshwater. One of the half-reactions taking place during the electrocatalytic splitting of seawater is oxygen evolution (OER). [...] Read more.
The perfect strategy for the generation of green and renewable hydrogen (H2) fuels is the direct electrocatalytic splitting of plentiful seawater rather than scarce freshwater. One of the half-reactions taking place during the electrocatalytic splitting of seawater is oxygen evolution (OER). However, the OER is affected by slow four-electron transfer kinetics as well as competitive chlorine evolution reactions (CERs) in seawater. To overcome the kinematic and competitive barriers of seawater splitting and achieve an excellent overall performance of seawater splitting, we herein report a facile, low-cost, one-step fabrication procedure of 3D structured nickel–manganese (NiMn) coatings using a dynamic hydrogen bubble template (DHBT) technique. The electrocatalytic activities of the thus synthesized catalytic materials for OER in simulated seawater (0.5 M NaCl + 1 M KOH, denoted as SSW) and alkaline natural seawater (natural seawater + 1 M KOH, denoted as ASW) were investigated using linear sweep voltammetry (LSV) at varying temperatures from 25 to 75 °C. Scanning electron microscopy (SEM) and inductively coupled plasma–optical emission spectroscopy (ICP–OES) were used to examine the surface morphology and composition of the prepared catalysts. It was found that the prepared NiMn/Ti-1 catalyst in a plating bath containing a molar ratio of 1:1 Ni2+:Mn2+ and having the lowest Mn loading of 13.43 µg cm−2 exhibited quite reasonable activity for OER in Cl− ion rich SSW and ASW. To achieve the benchmark current density of 10 mA cm−2 in SSW and ASW, the NiMn/Ti-1 electrocatalyst requires overpotentials of 386 and 388 mV, respectively. In addition, this optimal bimetallic electrocatalyst also demonstrated superior long-run stability at 1.81 V (vs. RHE) and 10 mA cm−2 for 24 h in both working electrolytes. Impressively, the two-electrode electrolyzer—NiMn/Ti-5(−)||NiMn/Ti-1(+)—needs only 1.619 V to deliver 10 mA cm−2 current density for overall alkaline seawater electrolysis, which is even 0.075 V lower than the noble metal-based electrolyzer (Pt(−)||NiMn/Ti-1(+)). Full article
(This article belongs to the Special Issue New Advance in Nanoparticles, Fiber, and Coatings)
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15 pages, 9882 KiB  
Article
Coated Biodegradable Zinc Lithium Alloys: Development and Characterization of Co-Doped Strontium Copper Tricalcium Phosphate Coating for Antimicrobial Applications
by Julietta V. Rau, Angela De Bonis, Mariangela Curcio, Katia Barbaro, Marco Fosca, Inna V. Fadeeva, Giovana Collombaro Cardoso, Roberto Teghil, Tatiana K. Slonskaya and Yufeng Zheng
Coatings 2024, 14(8), 1073; https://doi.org/10.3390/coatings14081073 - 22 Aug 2024
Viewed by 842
Abstract
Zinc biodegradable implants represent a revolutionary advancement in medical technology, offering a promising alternative to titanium and stainless-steel implants and avoiding the need for secondary surgeries for removal. In this study, we aimed to fulfil the clinical demand for biodegradable implant materials by [...] Read more.
Zinc biodegradable implants represent a revolutionary advancement in medical technology, offering a promising alternative to titanium and stainless-steel implants and avoiding the need for secondary surgeries for removal. In this study, we aimed to fulfil the clinical demand for biodegradable implant materials by applying a coating of double-doped strontium and copper resorbable tricalcium phosphate (SrCu-TCP) onto a zinc-lithium (Zn-Li) biodegradable alloy using the Pulsed Laser Deposition method. The coated surfaces were thoroughly characterized using X-ray Diffraction, Fourier Transform Infrared Spectroscopy, Atomic Force Microscopy, and Scanning Electron Microscopy coupled with Energy Dispersive X-ray. Microbiology experiments were conducted to assess the inhibitory effects on the growth of various bacteria strains, including gram-positive Staphylococcus aureus and Enterococcus faecalis, gram-negative Pseudomonas aeruginosa and Escherichia coli, as well as the fungus Candida albicans. The obtained results showed that the roughness of the Zn-Li alloy increased from 91.8 ± 29.4 to 651.0 ± 179.5 nm when coated with SrCu-TCP. The thickness of the coating ranged between 3–3.5 µm. The inhibition of growth for all four bacteria strains and the fungus was in the range of 24–35% when cultured on SrCu-TCP coated Zn-Li samples. These findings suggest that the developed coatings are promising candidates for applications requiring inhibition of microorganisms. Full article
(This article belongs to the Collection Feature Paper Collection in 'Surface Coatings for Biomedicine and Bioengineering')
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12 pages, 7766 KiB  
Article
Effect of Aluminide Coating Thickness on High-Temperature Fatigue Response of MAR-M247 Nickel-Based Superalloy
by Mateusz Kopec
Coatings 2024, 14(8), 1072; https://doi.org/10.3390/coatings14081072 - 21 Aug 2024
Cited by 1 | Viewed by 768
Abstract
In this paper, 20 µm and 40 µm thick aluminide coatings were deposited on MAR-M247 nickel-based superalloy through the chemical vapor deposition (CVD) process in a hydrogen protective atmosphere for 4 h and 12 h, respectively, at a temperature of 1040 °C and [...] Read more.
In this paper, 20 µm and 40 µm thick aluminide coatings were deposited on MAR-M247 nickel-based superalloy through the chemical vapor deposition (CVD) process in a hydrogen protective atmosphere for 4 h and 12 h, respectively, at a temperature of 1040 °C and an internal pressure of 150 mbar. The effect of aluminide coating thickness on the high-temperature performance of the MAR-M247 nickel-based superalloy was examined during a fatigue test at 900 °C. After high-temperature testing, the specimens were subjected to fractographic analysis to reveal the damage mechanisms. No significant effect of coating thickness was found since the material exhibited a similar service life throughout the fatigue test when subjected to the same stress amplitude. One should stress that the coating remained well adhered after specimen fracture, confirming its effectiveness in protecting the material against high-temperature oxidation. Full article
(This article belongs to the Special Issue Advances in Experimental Testing of Thermal Barrier Coatings)
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23 pages, 21700 KiB  
Article
Experimental Study on the Effect of Temperature on the Characteristics of Cutterhead Mud Cake in Complex Red-Bed Geology
by Jinshuo Yan, Xingwei Xue, Kaiwen Xue, Chaofan Gong and Kexin Zhang
Coatings 2024, 14(8), 1071; https://doi.org/10.3390/coatings14081071 - 21 Aug 2024
Viewed by 736
Abstract
Mud caking on shield cutterhead is a critical issue for tunnel safety, and temperature and duration are factors that can affect the characteristics of mud cake. Therefore, the aim of this study is to explore the characteristics of different temperatures and action times [...] Read more.
Mud caking on shield cutterhead is a critical issue for tunnel safety, and temperature and duration are factors that can affect the characteristics of mud cake. Therefore, the aim of this study is to explore the characteristics of different temperatures and action times on the adhesion and hardness of red-bed geological mud cake. A self-designed experimental apparatus was used to simulate the adhesion of mud cake on the cutterhead. The adhesion and hardness of the mud cake were analyzed through mud cake shedding tests and hardness tests. In addition, water film theory is used to analyze the adhesion mechanism of the mud cake. The results indicate that temperature and duration are key factors affecting mud cake shedding. Within the range of 25~150 °C, mud cake shedding efficiency is positively correlated with temperature and duration. However, temperatures above 150 °C promote the sintering of the mud cake, reducing its shedding efficiency. The hardness of the mud cake increases with temperatures above 150 °C, where the mud cake hardens and sinters, increasing the difficulty of shield tunneling. The water content of mud cake is influenced by temperature and time, affecting the amount of mud cake shedding. As the water content increases, the shedding initially decreases and then increases, reaching its minimum at about 30%, where the adhesion is strongest. By controlling the temperature and time, the water content can be optimized, improving the handling of mud cake. Full article
(This article belongs to the Special Issue Development and Characterization of New Construction Materials and Coatings)
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11 pages, 3023 KiB  
Article
Optical Bistability Based on MoS2 in the Kretschmann–Raether Configuration at Visible Light Frequencies
by Haishan Tian, Songqing Tang, Leyong Jiang, Huabing Wang, Jingke Zhang and Gang Sun
Coatings 2024, 14(8), 1070; https://doi.org/10.3390/coatings14081070 - 21 Aug 2024
Viewed by 514
Abstract
In this study, we theoretically study the optical bistability (OB) of reflected light beams at visible light frequencies by using a Kretschmann–Raether (KR) configuration where double-layer MoS2 is inserted. This OB phenomenon results from the local field enhancement owing to the excitation [...] Read more.
In this study, we theoretically study the optical bistability (OB) of reflected light beams at visible light frequencies by using a Kretschmann–Raether (KR) configuration where double-layer MoS2 is inserted. This OB phenomenon results from the local field enhancement owing to the excitation of metal surface plasmon polaritons (SPPs) and the introduction of the double-layer MoS2. By considering the third-order conductivity of MoS2, we obtain a threshold electric field with an incident electric field of 107 V/m levels. Furthermore, the influences of the structural parameters on the hysteretic behavior as well as the threshold of OB are clarified. This tunable OB phenomenon will provide possible options for nonlinear optical bistable devices. Full article
(This article belongs to the Special Issue Optical Properties of Crystals and Thin Films, Volume II)
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17 pages, 4923 KiB  
Article
Effect of Chloride Salt Erosion on the Properties of Straw Fiber Reactive Powder Concrete
by Hangyang Wang, Kaiwei Gong, Bingling Cheng, Xi Peng, Hui Wang and Bin Xu
Coatings 2024, 14(8), 1069; https://doi.org/10.3390/coatings14081069 - 21 Aug 2024
Cited by 1 | Viewed by 787
Abstract
Straw fibers are renowned for their cost-effectiveness, sustainability, and durability. They represent a promising natural reinforcement option for reactive powder concrete (RPC). This paper investigated the impact of straw fibers on RPC’s workability, mechanical performance (mechanical strength and flexural toughness), and electrical properties [...] Read more.
Straw fibers are renowned for their cost-effectiveness, sustainability, and durability. They represent a promising natural reinforcement option for reactive powder concrete (RPC). This paper investigated the impact of straw fibers on RPC’s workability, mechanical performance (mechanical strength and flexural toughness), and electrical properties (electrical resistance and AC impedance spectroscopy curves). The straw fiber volumes ranged from 1% to 4.0% of the total RPC volume. Specimens were cured under standard curing conditions for 3, 7, 14, and 28 days. Mechanical and electrical properties of the specimens were tested before chloride salt erosion. The mass loss and ultrasonic velocity loss of the samples were measured under NaCl freeze–thaw cycles (F-Cs). The mass loss, ultrasonic velocity loss, and mechanical strengths loss of the samples were measured under NaCl dry–wet alternations (D-As). The findings indicated that incorporating straw fibers enhanced RPC’s flexural strength, compressive strength, and flexural toughness by 21.3% to 45.76%, −7.16% to 11.62%, and 2.4% to 32.7%, respectively, following a 28-day curing period. The addition of straw fibers could augment the AC electrical resistance of the RPC by 10.17% to 58.1%. The electrical characteristics of the RPC adhered to series conduction models. A power function relationship existed between the electrical resistance and mechanical strengths of the RPC. After 10 NaCl D-As, the mass loss rate, ultrasonic velocity loss rate, flexural strength, and compressive strength loss rates of the RPC decreased by 0.42% to 1.68%, 2.69% to 6.73%, 9.6% to 35.65%, and 5.41% to 34.88%, respectively, compared to blank samples. After undergoing 200 NaCl F-Cs, the rates of mass loss and ultrasonic velocity loss of the RPC decreased by 0.89% to 1.01% and 6.68% to 8.9%, respectively. Full article
(This article belongs to the Special Issue Surface Engineering and Mechanical Properties of Building Materials)
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12 pages, 7017 KiB  
Article
Microstructures and Properties of Laser-Cladded FeCoCrNiAlTi High-Entropy Alloy with Intensive Repair Potential
by Hao Yu, Bo Liu, Debin Wang, Guofeng Han, Dong Han and Baijun Yang
Coatings 2024, 14(8), 1068; https://doi.org/10.3390/coatings14081068 - 21 Aug 2024
Viewed by 781
Abstract
As a key step in intensive additive repair, the design of intensive repair materials immediately needs to be explored. In this work, an intensive additive repair study based on laser cladding technology was performed using a self-designed Fe20Co25Ni31 [...] Read more.
As a key step in intensive additive repair, the design of intensive repair materials immediately needs to be explored. In this work, an intensive additive repair study based on laser cladding technology was performed using a self-designed Fe20Co25Ni31Cr8Al9Ti7 high-entropy alloy (HEA) powder and three types of substrates widely used in field equipment (namely, Q235, 17CrNiMo6H, and 304 stainless steel). The results revealed that the HEA repair layer (HEA-RL) consists of a dominant FCC phase and a small amount of BCC phase, and the microstructure shows the columnar-to-equiaxed grain transition behavior. The metallurgical bonding between the HEA-RL and the three substrates has almost no defects. Compared with the three substrates, the HEA-RL has a much higher microhardness (~340 HV) and decent corrosion resistance. Therefore, the underlying mechanisms for the microstructure and performance of the HEA-RL were also discussed. This work provides a new idea for the design of intensive repair materials. Full article
(This article belongs to the Special Issue Research and Application of High Entropy Alloys)
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15 pages, 5469 KiB  
Article
High-Temperature Hot Corrosion Resistance of CrAl/NiCoCrAlY/AlSiY Gradient Composite Coating on TiAl Alloy
by Yuanyuan Sun, Qiang Miao, Shijie Sun, Wenping Liang, Zheng Ding, Jiangqi Niu, Feilong Jia, Jianyan Xu and Jiumei Gao
Coatings 2024, 14(8), 1067; https://doi.org/10.3390/coatings14081067 - 20 Aug 2024
Cited by 1 | Viewed by 865
Abstract
TiAl alloys are used in high-temperature components such as the turbine blades of aeroengines because of their excellent properties. However, TiAl alloys are prone to thermal corrosion when in near-ocean service. In order to solve this problem, a hot-corrosion-resistant CrAl/NiCoCrAlY/AlSiY gradient composite coating [...] Read more.
TiAl alloys are used in high-temperature components such as the turbine blades of aeroengines because of their excellent properties. However, TiAl alloys are prone to thermal corrosion when in near-ocean service. In order to solve this problem, a hot-corrosion-resistant CrAl/NiCoCrAlY/AlSiY gradient composite coating was prepared on the surface of the TiAl alloy. The phase composition and morphology of the coating were analyzed. Hot corrosion tests of the traditional NiCoCrAlY coating and CrAl/NiCoCrAlY/AlSiY gradient composite coating on a TiAl substrate were performed. The samples were coated with 75%Na2SO4 + 25%NaCl salt film and treated at 950 °C for 100 h, and the corrosion products were analyzed. The results indicate that compared with the TiAl substrate and traditional NiCoCrAlY-coated samples, the composite coating showed better hot corrosion resistance, only slightly cracking, and no corrosion loss occurred. This is mainly because the continuous Al2O3 layer can effectively resist the damage caused by the melting reaction in salt, and the Cr-rich layer can not only slow the mutual diffusion of elements but also generate a good corrosion resistance chromium oxide protective layer under serious corrosion. Moreover, the corrosion mechanism of the TiAl substrate, traditional NiCoCrAlY coating, and experimental composite coating was analyzed in detail. Full article
(This article belongs to the Special Issue High-Temperature Corrosion and Oxidation of Metals and Alloys)
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16 pages, 3828 KiB  
Article
Effects of Nitriding and Thermal Processing on Wear and Corrosion Resistance of Vanadis 8 Steel
by Alejandro González-Pociño, Florentino Alvarez-Antolin and Luis Borja Peral-Martinez
Coatings 2024, 14(8), 1066; https://doi.org/10.3390/coatings14081066 - 20 Aug 2024
Viewed by 725
Abstract
Vanadis 8 steel is a tool steel manufactured by powder metallurgic processing. Its main alloy elements are V, Cr and Mo. By implementing an experimental design with five factors—all of them are related to the thermal processing of this steel and with ionic [...] Read more.
Vanadis 8 steel is a tool steel manufactured by powder metallurgic processing. Its main alloy elements are V, Cr and Mo. By implementing an experimental design with five factors—all of them are related to the thermal processing of this steel and with ionic nitriding—the effects of said factors on adhesive wear resistance and corrosion resistance were studied. For this purpose, Pin-on-Disc wear tests and lineal polarization resistance tests were carried out using an aqueous solution with 3.5% NaCl by weight. The main aim was to increase this steel use in more aggressive environmental conditions, such as in coastal environments. By means of XRD, the percentage of retained austenite was determined, and by SEM-EDX, the microstructure was revealed. The conclusion is that adhesive wear resistance is improved if thermal processing parameters are at such levels that increase austenite destabilization and reduce retained austenite content. This means to destabilize austenite at 1180 °C during 1 h, with oil quenching, tempering at 520 °C during 2 h and ionic nitriding at 520 °C during 2 h. Corrosion resistance is highly improved with ionic nitriding. At the same time, to compensate for the negative effect on corrosion resistance of a high density of primary and secondary carbides, it is essential to carry out the ionic nitriding treatment. The harmful effect of electrochemical microcells that appear in the carbide/matrix interface is compensated by the passivating effect generated by the nitrided surface. Full article
(This article belongs to the Special Issue Heat Treatment and Surface Engineering of Tools and Dies)
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18 pages, 26175 KiB  
Article
Influence of Scanning Paths on the Weld Pool Behavior, Microstructure, and Mechanical Property of AA2060 Al-Li Alloy Joints by Laser Beam Oscillation Welding
by Yanbo Song, Ying Liang, Hongbing Liu, Luchan Lin, Yanfeng Gao, Hua Zhang and Jin Yang
Coatings 2024, 14(8), 1065; https://doi.org/10.3390/coatings14081065 - 20 Aug 2024
Viewed by 870
Abstract
In this paper, the laser beam oscillation welding (LBOW) was utilized to weld a 2 mm thick AA2060 aluminum-lithium (Al-Li) alloy plate. The weld pool behaviors under three scanning paths (pure laser, O-shaped, and ∞-shaped) were investigated. It was observed that the O-shaped [...] Read more.
In this paper, the laser beam oscillation welding (LBOW) was utilized to weld a 2 mm thick AA2060 aluminum-lithium (Al-Li) alloy plate. The weld pool behaviors under three scanning paths (pure laser, O-shaped, and ∞-shaped) were investigated. It was observed that the O-shaped scanning path resulted in the most stable welding process. In addition, the weld macroscopic formation, microstructure, and mechanical property between different paths were studied. The results showed that pure laser and ∞-shaped patterns produced welding defects such as spatters and collapse during the welding process, while the O-shaped pattern exhibited good macroscopic formation at varying laser powers. The O-shaped pattern promoted the finest grain in the weld center and reduced the heat input during the welding process. The equiaxed grain zone (EQZ) width of the O-shaped pattern is the smallest compared to the other two patterns at high laser power. In addition to this, the O-shaped pattern could effectively reduce the porosity in the weld. When an O-shaped scanning pattern was adopted at the ideal laser power parameter of 3000 W, the microhardness of the weld center increased by approximately 5.6% compared to pure laser mode. Full article
(This article belongs to the Special Issue Effects of Laser Treatment on Surface Characterization and Mechanical Properties of Alloys)
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2 pages, 480 KiB  
Correction
Correction: Abatal et al. Comparison of Heavy Metals Removal from Aqueous Solution by Moringa oleifera Leaves and Seeds. Coatings 2021, 11, 508
by Mohamed Abatal, M. T. Olguin, Ioannis Anastopoulos, Dimitrios A. Giannakoudakis, Eder Claudio Lima, Joel Vargas and Claudia Aguilar
Coatings 2024, 14(8), 1064; https://doi.org/10.3390/coatings14081064 - 20 Aug 2024
Viewed by 486
Abstract
The main goal of the work was to study the Moringa oleifera leaves and seeds as sorbents against Pb(II), Cd(II), Co(II), and Ni(II) from aqueous solutions, to explore the effect of various parameters (such as contact time, biosorbent dosage, and initial concentration of [...] Read more.
The main goal of the work was to study the Moringa oleifera leaves and seeds as sorbents against Pb(II), Cd(II), Co(II), and Ni(II) from aqueous solutions, to explore the effect of various parameters (such as contact time, biosorbent dosage, and initial concentration of metals) and to determine the adsorption mechanisms [...] Full article
(This article belongs to the Section Environmental Aspects in Colloid and Interface Science)
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15 pages, 1353 KiB  
Review
A Review of High-Speed Turning of AISI 4340 Steel with Minimum Quantity Lubrication (MQL)
by Haniff Abdul Rahman, Nabil Jouini, Jaharah A. Ghani and Mohammad Rasidi Mohammad Rasani
Coatings 2024, 14(8), 1063; https://doi.org/10.3390/coatings14081063 - 19 Aug 2024
Viewed by 1048
Abstract
AISI 4340 is a medium-carbon low-alloy steel that has gained distinctive attention due to its advanced properties including high strength, high toughness, and heat resistance. This has led to its commercial usage in a wide variety of industries such as construction, automotive, and [...] Read more.
AISI 4340 is a medium-carbon low-alloy steel that has gained distinctive attention due to its advanced properties including high strength, high toughness, and heat resistance. This has led to its commercial usage in a wide variety of industries such as construction, automotive, and aerospace. AISI 4340 is usually machined in a hardened state through a hard-turning process, which results in high heat generation, accelerated tool wear, low productivity, and poor surface quality. The application of high-speed machining helps improve the material removal rate and surface finish quality, yet the elevated temperature at the cutting zone still poses problems to the tool’s lifespan. Apart from using advanced cutting tool materials, which is costly, researchers have also explored various cooling methods to tackle the heat problem. This paper presents a review of a sustainable cooling method known as minimum quantity lubrication (MQL) for its application in the high-speed turning of AISI 4340 steel. This study is centered on high-speed turning and the application of MQL systems in machining AISI 4340 steel. It has been observed that the hard part turning of materials with a hardness exceeding 45 HRC offers advantages such as improved accuracy and tighter tolerances compared to traditional grinding methods. However, this process leads to increased temperatures, and MQL proves to be a viable alternative to dry conditions. Challenges in optimizing MQL performance include fluid penetration and lubrication effectiveness. Full article
(This article belongs to the Special Issue Latest Insights in Metal Fatigue, Failure, and Fracture)
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15 pages, 6565 KiB  
Article
Research on the Measurement and Estimation Method of Wheel Resistance on a Soil Runway
by Zihan Wang, Xiaolei Chong, Guanhu Wang, Chaojia Liu and Jichao Zhang
Coatings 2024, 14(8), 1062; https://doi.org/10.3390/coatings14081062 - 19 Aug 2024
Cited by 1 | Viewed by 657
Abstract
In view of the fact that there is no suitable measurement method for tire driving resistance during the operation of a transporter on soil pavement, this paper proposes a simple measurement and estimation method for driving resistance on a soil runway based on [...] Read more.
In view of the fact that there is no suitable measurement method for tire driving resistance during the operation of a transporter on soil pavement, this paper proposes a simple measurement and estimation method for driving resistance on a soil runway based on the Bekker settlement model. In this paper, using the driving resistance equation based on the Bekker model, a simplified equation of driving resistance related to mass is proposed. Using the principle of kinematics, a simple test device for driving resistance was developed, and the test data of the test device were used to determine the parameters of the driving resistance estimation equation of the road surface. The driving resistance of the wheel running state was tested by the simulated aircraft load loading vehicle through the mechanical sensor, and the consistency between the theoretical value and the actual value of the driving resistance value under 8T, 10T, and 12T loads was verified. This research shows that the test method and estimation method have low cost and good accuracy and are suitable for wide promotion. The results of this paper provide a new idea and method for estimating the driving resistance of a wheel when a transporter runs on a soil road and also provide a reference for designing the length of a soil runway. Full article
(This article belongs to the Special Issue Surface Science of Degradation and Surface Protection)
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13 pages, 2975 KiB  
Article
Impact of Carbon Fiber Content and Length on the Rheological Properties and Coating Performance for Lost Foam Casting
by Guojin Sun, Linqian Xu and Qi Wang
Coatings 2024, 14(8), 1061; https://doi.org/10.3390/coatings14081061 - 19 Aug 2024
Viewed by 683
Abstract
This study explores the impact of carbon fiber length and content on the rheological properties and performance of coatings used in lost foam casting. The investigation encompassed fiber lengths of 1 mm, 3 mm, and 6 mm and fiber contents of 0.2%, 0.5%, [...] Read more.
This study explores the impact of carbon fiber length and content on the rheological properties and performance of coatings used in lost foam casting. The investigation encompassed fiber lengths of 1 mm, 3 mm, and 6 mm and fiber contents of 0.2%, 0.5%, and 0.8%. The effects on coating viscosity, shear stress, coating weight, and surface morphology were meticulously evaluated. The results demonstrate that incorporating carbon fibers significantly enhances coating viscosity and shear stress compared to fiber-free coatings, with more pronounced effects observed at higher fiber contents and longer fiber lengths. Nevertheless, excessive fiber contents and lengths can lead to agglomeration, negatively impacting coating uniformity. The optimal fiber length and content were identified, striking a balance between improved rheological properties and coating performance. These findings provide critical insights for the development and industrial application of high-performance coatings in lost foam casting. Full article
(This article belongs to the Special Issue Advances in Polymer Composites, Coatings and Adhesive Materials)
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25 pages, 11990 KiB  
Review
Bibliometric Study of Electrochemical Advanced Oxidation Processes (EAOPs) for Wastewater Treatment
by Tanja P. Brdarić, Danka D. Aćimović, Ľubomír Švorc and Dragana D. Vasić Anićijević
Coatings 2024, 14(8), 1060; https://doi.org/10.3390/coatings14081060 - 19 Aug 2024
Viewed by 1344
Abstract
Electrochemical advanced oxidation processes (EAOPs) are at the forefront of scientific research as green technologies aimed at effectively purifying polluted aquatic environments. These methods utilize electrochemical processes to generate reactive oxygen species (ROS), such as the hydroxyl radical (•OH), either on the anode [...] Read more.
Electrochemical advanced oxidation processes (EAOPs) are at the forefront of scientific research as green technologies aimed at effectively purifying polluted aquatic environments. These methods utilize electrochemical processes to generate reactive oxygen species (ROS), such as the hydroxyl radical (•OH), either on the anode surface or within the bulk solution, which can partially degrade or completely mineralize organic pollutants. The aim of the article is to provide a bibliometric analysis of research articles specifically focused on the application and development of EAOPs in wastewater treatment over the past five years. Utilizing the most extensive database for literature searches, Web of Science Core Collection (WoS), which encompasses 95% of global publications, a total of 649 research articles were retrieved by limiting the search results to words associated with EAOPs in titles, keywords, and abstracts. The bibliometric dataset was then processed using CiteSpace and VOSviewer software. The People’s Republic of China is emerging as the country with the highest production in the field, demonstrating a strong commitment to research and a leading role in international cooperation. This leadership is evident through China’s substantial contributions to the body of literature and its extensive network of collaborations with researchers worldwide. Meanwhile, Australia, despite producing fewer publications, has achieved a high citation rate, underscoring the significant impact and influence of its research within the scientific community. One of the most promising and extensively studied topics in this field is the electro-Fenton process, which has garnered considerable attention due to its potential applications and remarkable efficiency in various contexts. The bibliometric analysis conducted in this study allowed for a detailed visualization of the currently available literature data and corresponding developing trends. By mapping out the key areas of focus, prominent researchers, influential journals, and collaborative networks, this analysis provides valuable insights. These insights can facilitate future joint research endeavors, enhance collaboration, and promote the sharing of knowledge and best practices among researchers globally. Full article
(This article belongs to the Special Issue Advanced Technology in Environmental Remediation and Resource Utilization, 2nd Edition)
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10 pages, 2226 KiB  
Article
Modification of the Crumb Rubber Asphalt by Eucommia Ulmoides Gum under a High-Temperature Mixing Process
by Yueyang Shi, Zongliang Tong, Qingbo Ren, Zhigang Li and Jingling Wang
Coatings 2024, 14(8), 1059; https://doi.org/10.3390/coatings14081059 - 19 Aug 2024
Viewed by 611
Abstract
The crumb rubber (CR) asphalt has some defects of high viscosity and poor storage stability, which brings great challenge to the high-quality construction of the CR asphalt pavement. To improve the interaction between the CR and base binder, the Eucommia ulmoides gum (EUG) [...] Read more.
The crumb rubber (CR) asphalt has some defects of high viscosity and poor storage stability, which brings great challenge to the high-quality construction of the CR asphalt pavement. To improve the interaction between the CR and base binder, the Eucommia ulmoides gum (EUG) with double-bond structure similar to trans-polyoctenamer rubber (TOR) was used to modify the CR asphalt. However, the original EUG double bond is basically inactive at room temperature and cannot form the effect of TOR. Open double bonds of EUG with asphalt and rubber powder form a network structure similar to TOR-modified rubber asphalt by high-temperature mixing with EUG in a torque rheometer. The effects of modified CR on rubber asphalt were analyzed by macro- and micro-experiments such as rotational viscosity tests, segregation tests, FTIR tests, and PG tests. It was found that the high-temperature mixing process works in both physical and chemical ways to mix the CR and EUG into an inseparable substance. The modified CR has higher chemical activity after desulfurization and degradation, which allows it to form a more effective chemical connection with asphalt. EUG can build a stable spatial crosslinking structure in CR asphalt due to the sulfurization reaction, which significantly improves the construction workability and system stability of the CR asphalt. Full article
(This article belongs to the Special Issue Surface Engineering and Mechanical Properties of Building Materials)
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16 pages, 7030 KiB  
Article
Facile Preparation of Smart Sponge Based on a Zeolitic Imidazolate Framework for the Efficient Separation of Oily Wastewater
by Yuping Zhang, Xinxin Chen, Pei Yuan, Haie Chen and Songwei Li
Coatings 2024, 14(8), 1058; https://doi.org/10.3390/coatings14081058 - 18 Aug 2024
Viewed by 853
Abstract
The fabrication of durable materials with excellent oil-adsorption capacity and separation performance for the treatment of oily wastewater is meaningful based on the special property of smart responsiveness. Herein, a solvent-responsive melamine sponge (MS) was developed via silanization and the in situ growth [...] Read more.
The fabrication of durable materials with excellent oil-adsorption capacity and separation performance for the treatment of oily wastewater is meaningful based on the special property of smart responsiveness. Herein, a solvent-responsive melamine sponge (MS) was developed via silanization and the in situ growth of a zeolitic imidazolate framework-8 (ZIF-8). Detailed characterization of the resultant composite MS was conducted using scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), and X-ray diffraction (XRD). The multiscale hierarchical MS substrate exhibited highly hydrophobic properties in the pH range of 1–11, along with a satisfactory adsorption capacity in the range of 65.4–134.2 g/g for different oils. The modified surface transformed from superhydrophobic/superlipophilic to superhydrophilic/underwater superoleophobic upon ethanol wetting, reverting to its original superhydrophobic state upon drying. The separation flux of the MS substrate was above 1.5 × 104 L/m2h for both oil and water removal, and the separation efficiency was greater than 98.7%. The absence of obvious changes in separation performance after 50 successive immiscible oil−water separations indicated the excellent durability and robustness of the anchored ZIF-8 nanoparticles on the surface of the modified MS substrate. More importantly, oil-in-water emulsion separation was successfully carried out via the ZIF-8 MS composite, showing high separation efficiency (over 99.1%). The developed smart sponge, which had high oil-adsorption capacity, excellent chemical stability, and fire resistance, has a wide range of potential practical applications in the convenient treatment of oily wastewater. Full article
(This article belongs to the Special Issue Recent Advances in Surface Functionalisation)
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11 pages, 8007 KiB  
Article
Surprising Effects of Al2O3 Coating on Tribocatalytic Degradation of Organic Dyes by CdS Nanoparticles
by Senhua Ke, Chenyue Mao, Ruiqing Luo, Zeren Zhou, Yongming Hu, Wei Zhao and Wanping Chen
Coatings 2024, 14(8), 1057; https://doi.org/10.3390/coatings14081057 - 18 Aug 2024
Viewed by 950
Abstract
With a band gap of 2.4 eV, CdS has been extensively explored for photocatalytic applications under visible light irradiation. In this study, CdS nanoparticles have been investigated for the tribocatalytic degradation of concentrated Rhodamine B (RhB) and methyl orange (MO) solutions. For CdS [...] Read more.
With a band gap of 2.4 eV, CdS has been extensively explored for photocatalytic applications under visible light irradiation. In this study, CdS nanoparticles have been investigated for the tribocatalytic degradation of concentrated Rhodamine B (RhB) and methyl orange (MO) solutions. For CdS nanoparticles in a glass beaker, 78.9% of 50 mg/L RhB and 69.8% of 20 mg/L MO solutions were degraded after 8 h and 24 h of magnetic stirring using Teflon magnetic rotary disks, respectively. While for CdS nanoparticles in a beaker with Al2O3 coated on its bottom, 99.8% of the RhB solution was degraded after 8 h of magnetic stirring and 95.6% of the MO solution was degraded after 12 h of magnetic stirring. Moreover, another contrast was observed between the two beaker bottoms—a new peak at 250 nm in UV–visible absorption spectra was only observed for the MO degradation by CdS in the as-received glass beaker, which indicates that MO molecules were only broken into smaller organic molecules in that case. These findings are meaningful for expanding the catalytic applications of CdS and for achieving a better understanding of tribocatalysis as well. Full article
(This article belongs to the Special Issue Coatings as Key Materials in Catalytic Applications)
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22 pages, 5390 KiB  
Article
Research on the Water Absorption and Release Characteristics of a Carbonized γ-C2S Lightweight Aggregate in Lightweight and High-Strength Concrete
by Zi Yu, Chenxi Liu, Jinhui Li, Jing Wu, Xueting Ma, Yugui Cao, Jierong Cao, Weiheng Xiang, Hua Wang and Qingjun Ding
Coatings 2024, 14(8), 1056; https://doi.org/10.3390/coatings14081056 - 18 Aug 2024
Viewed by 878
Abstract
Lightweight aggregate concrete, known for its light weight, thermal insulation, and excellent durability, has garnered significant attention and is considered an ideal material for lightweight ultra-high-performance concrete. Previous research has discovered that prewetting lightweight aggregates can continuously release water during the setting and [...] Read more.
Lightweight aggregate concrete, known for its light weight, thermal insulation, and excellent durability, has garnered significant attention and is considered an ideal material for lightweight ultra-high-performance concrete. Previous research has discovered that prewetting lightweight aggregates can continuously release water during the setting and hardening process of concrete, providing internal curing. However, the moisture release behavior of prewetted lightweight aggregates under different temperature and humidity conditions, as well as their internal curing mechanisms in low water–cement ratio mixtures, remains unclear and requires further investigation. In response to environmental sustainability, this study utilizes industrial waste γ-C2S to produce a high-strength carbonized γ-C2S lightweight aggregate (CC) and primarily compares the water absorption and release characteristics of three different types of lightweight aggregates, focusing on the influence of curing temperature and humidity on the water release behavior of the prewetted CC and establishing a water release model for the prewetted CC in cement-based materials. The experimental results indicate that the water absorption rates of the self-made high-performance lightweight aggregate (CC), magnesian lightweight aggregate (MC), and shale lightweight aggregate (SC) conform to the typical Boxlucas equation. In an air environment, the CC has the longest water release duration, followed by the MC, with the SC being the fastest. The water storage performance of the prewetted SC was poor, while the 100% prewetted CC exhibited better water storage during the mixing stage. When the CC is 100% prewetted, it can significantly increase the free water content in the interfacial transition zone, aiding in the hydration of the interfacial transition zone and enhancing the efficiency of shrinkage compensation by the expansive agent. This improvement contributes to the mechanical strength and volumetric stability of cement-based materials. Full article
(This article belongs to the Special Issue Effective Coating Barriers for Protection of Reinforced Concrete, 2nd Edition)
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16 pages, 4424 KiB  
Article
Mechanism of Ag-SiO2-TiO2 Nanocomposite Coating Formation on NiTi Substrate for Enhanced Functionalization
by Karolina Dudek, Mateusz Dulski, Jacek Podwórny, Magdalena Kujawa and Patrycja Rawicka
Coatings 2024, 14(8), 1055; https://doi.org/10.3390/coatings14081055 - 18 Aug 2024
Viewed by 784
Abstract
The functionality of the NiTi shape memory alloy was improved through engineering Ag-SiO2-TiO2 nanocomposite coatings. For this purpose, an anaphoretic deposition process, conducted at a constant voltage of 40 V and deposition times ranging from 1 to 10 min, was [...] Read more.
The functionality of the NiTi shape memory alloy was improved through engineering Ag-SiO2-TiO2 nanocomposite coatings. For this purpose, an anaphoretic deposition process, conducted at a constant voltage of 40 V and deposition times ranging from 1 to 10 min, was used. Scanning electron microscopy (SEM) analysis demonstrated that the deposition parameters significantly impacted the morphology of the coatings. Complementary Raman Spectroscopy and X-ray diffraction (XRD) analyses confirmed the successful formation of distinct nanocomposite layers, and revealed the details of their crystalline structure and chemical composition. After that, the adhesion between the NiTi substrate and the electrophoretically deposited ceramic coatings was improved through a post-deposition heat treatment. To prevent excessive shrinkage and cracking of the coating, tests were carried out to characterize the behavior of the coating material at elevated temperatures. The nanocomposite coatings were exposed to a temperature of 800 °C for 2 h. The annealing induced significant structural and morphological transformations, resulting in layers that were distinctly different from both the original materials and those produced solely through electrophoretic deposition. The thermal treatment resulted in the formation of a new kind of nanocomposite structure with enhanced reactivity. Full article
(This article belongs to the Section Surface Characterization, Deposition and Modification)
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18 pages, 9729 KiB  
Article
Properties of Laser-Clad Stainless Steel–Ni/WC Double-Layer Coatings
by Ruipeng Zhang, Yuhong Liao, Qingyi Sai, Shuwen Wang, David Barton and Mingwen Bai
Coatings 2024, 14(8), 1054; https://doi.org/10.3390/coatings14081054 - 18 Aug 2024
Viewed by 791
Abstract
In order to improve the wear and corrosion resistance and enhance the tribological and mechanical properties of gray cast iron, the laser surface cladding technique was employed to fabricate double-layer coatings with different Ni/WC ratios on the surface of gray cast iron. The [...] Read more.
In order to improve the wear and corrosion resistance and enhance the tribological and mechanical properties of gray cast iron, the laser surface cladding technique was employed to fabricate double-layer coatings with different Ni/WC ratios on the surface of gray cast iron. The effects of laser processing parameters and the type of Ni-based alloy on the microstructure and properties of the gray cast iron matrix and laser-clad layer were investigated. A 316L stainless steel transition layer was introduced between the gray cast iron substrate and the Ni/WC coating to prevent the cladding layer from cracking. The tribological and mechanical properties of the laser-clad coatings were characterized with various tests at the macro- and micro-scales; the residual stresses on the coating surfaces were measured, and electrochemical tests were also carried out. The microstructures of the clad layers were analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD). The results show that the laser-clad layers exhibit excellent vibration and noise reduction performance, which is partially due to the reduction and stabilization of the coefficients of friction (COFs) and the high levels of compressive residual stress on the surface of the laser-clad layers. The wear and corrosion resistance of the laser-clad layers are significantly improved, and the maximum wear loss of the laser-clad coating was about only 5% of that of the unclad gray cast iron substrate. This research has significance for the laser surface modification of cast iron, steel, and other metals, which is an increasingly important topic, especially in the automotive friction brake industry. Full article
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15 pages, 3645 KiB  
Article
Comparison of Corrosion Behavior of a-C Coatings Deposited by Cathode Vacuum Arc and Filter Cathode Vacuum Arc Techniques
by Zhiqing Feng, Zhetong Zhou, Junhao Zeng, Ding Chen, Fengying Luo, Qimin Wang, Wei Dai and Ruiming Zhang
Coatings 2024, 14(8), 1053; https://doi.org/10.3390/coatings14081053 - 17 Aug 2024
Viewed by 855
Abstract
This study explores the utilization of cathodic vacuum arc (CVA) technology to address the limitations of magnetron sputtering technology in preparing amorphous carbon (a-C) coatings, such as having a low ionization rate, low deposition rate, and insufficiently dense structure. Specifically, a-C coatings were [...] Read more.
This study explores the utilization of cathodic vacuum arc (CVA) technology to address the limitations of magnetron sputtering technology in preparing amorphous carbon (a-C) coatings, such as having a low ionization rate, low deposition rate, and insufficiently dense structure. Specifically, a-C coatings were prepared by the cathodic vacuum arc (CVA)and the filtered cathodic vacuum arc (FCVA) technology,, one with embedded carbon particles and one without, both having closely related carbon structures. Research is currently underway on bipolar plate coatings for fuel cells. The corrosion behavior of the prepared a-C coatings was examined through Tafel polarization analysis under simulated fuel cell operating conditions as well as potentiostatic analysis at 0.6 V under normal conditions and 1.6 V under start–stop conditions for 7200 s. The coatings before and after corrosion are characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy, and infrared spectroscopy. The results reveal that the incorporation of conductive graphite-like particles in the coatings reduces their contact resistance. However, the gaps between these particles and the coatings act as pathways for corrosive solution, exacerbating the corrosion of the coatings. After corrosion at 0.6 V, both sets of coatings with sp2-hybridized carbon structures are contaminated by elements such as hydrogen and oxygen, leading to an increase in their contact resistance. Under high potential conditions (1.6 V), large corrosion pits and defects appear at the locations of graphite-like carbon particles. Furthermore, both sets of samples exhibit more severe oxygen contamination and a transformation of broken carbon bonds from sp3- to sp2-hybridized forms, irrespective of whether embedded graphite particles are present. Full article
(This article belongs to the Special Issue Anti-corrosion and Anti-wear Coatings: Fundamentals, Technologies, and Applications)
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14 pages, 9812 KiB  
Article
One-Step Fabrication of Composite Hydrophobic Electrically Heated Graphene Surface
by Mian Zhong, Shichen Li, Hongyun Fan, Huazhong Zhang, Yong Jiang, Jinling Luo and Liang Yang
Coatings 2024, 14(8), 1052; https://doi.org/10.3390/coatings14081052 - 17 Aug 2024
Viewed by 886
Abstract
Ice accumulation poses considerable challenges in transportation, notably in the domain of general aviation. The present study combines the strengths and limitations of conventional aircraft deicing techniques with the emerging trend toward all-electric aircraft. This study aims to utilize laser-induced graphene (LIG) technology [...] Read more.
Ice accumulation poses considerable challenges in transportation, notably in the domain of general aviation. The present study combines the strengths and limitations of conventional aircraft deicing techniques with the emerging trend toward all-electric aircraft. This study aims to utilize laser-induced graphene (LIG) technology to create a multifunctional surface, seamlessly integrating hydrophobic properties with efficient electrical heating to mitigate surface icing effectively. We investigated the utilization of a 10.6 μm CO2 laser for direct writing on polyimide (PI), a widely used insulating encapsulation material. From the thermomechanical perspective, our initial analysis using COMSOL Multiphysics software (V5.6) revealed that when the laser power P exceeds 5 W, the PI substrate experiences ablative damage. The experimental results show that when P ≤ 5 W, an increase in power has a positive impact on the quality, surface porosity, roughness reduction, line-spacing reduction, and water contact-angle enhancement of the graphene. Conversely, when P > 5 W, higher power negatively affects both the substrate and the graphene structure by inducing excessive ablation. However, it influences the graphene line height positively and is consistent with overall experimental–simulation congruence. Furthermore, the incorporation of high-quality graphene resulted in a surface that exhibited higher contact angles (CA > 120°), lower energy consumption, and higher heating efficiency compared to the use of traditional electrically heated materials for anti-icing applications. The potential applications of this one-step fabrication method extend across various industries, particularly aviation, marine engineering, and other ice-prone domains. Moreover, the method has extensive prospects for addressing pivotal challenges associated with ice formation and serves as an innovative and efficient anti-icing technology. Full article
(This article belongs to the Special Issue Research Progress and Application of Super-hydrophobic Anti-icing Surface)
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17 pages, 12977 KiB  
Review
Current Status of Image Recognition Technology in the Field of Corrosion Protection Applications
by Xinran Wang, Wei Zhang, Zhifeng Lin, Haojie Li, Yuanqing Zhang, Weiyin Quan, Zhiwei Chen, Xueqiang You, Yang Zeng, Gang Wang, Bolin Luo and Zhenghua Yu
Coatings 2024, 14(8), 1051; https://doi.org/10.3390/coatings14081051 - 16 Aug 2024
Viewed by 833
Abstract
Corrosion brings serious losses to the economy annually. Therefore, various corrosion protection and detection techniques are widely used in the daily maintenance of large metal engineering structures. The emergence of image recognition technology has brought a more convenient and faster way for nondestructive [...] Read more.
Corrosion brings serious losses to the economy annually. Therefore, various corrosion protection and detection techniques are widely used in the daily maintenance of large metal engineering structures. The emergence of image recognition technology has brought a more convenient and faster way for nondestructive testing. Existing image recognition technology can be divided into two categories according to the algorithm: traditional image recognition technology and image recognition technology based on deep learning. These two types of technologies have been widely used in the three fields of metal, coating, and electrochemical data images. A large amount of work has been carried out to identify defects in metals and coatings, and deep learning-based methods also show potential for identifying electrochemical data images. Matching electrochemical images with the detection of defect morphology will bring a deeper understanding of image recognition techniques for metals and coatings. A database of accumulated morphology and electrochemical parameters will make it possible to predict the life of steel and coatings using image recognition techniques. Full article
(This article belongs to the Special Issue Corrosion Resistance, Mechanical Properties and Characterization of Metallic Materials and Coatings, 2nd Edition)
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20 pages, 18637 KiB  
Article
Poly(Lactide) Nonwoven Fabric with Iron Coating and Its Biological Properties
by Zdzisława Mrozińska, Małgorzata Świerczyńska, Michał Juszczak, Katarzyna Woźniak and Marcin H. Kudzin
Coatings 2024, 14(8), 1050; https://doi.org/10.3390/coatings14081050 - 16 Aug 2024
Cited by 1 | Viewed by 941
Abstract
The study investigated the biological properties of a composite material composed of poly(lactide) (PLA) and iron (Fe) produced by sputtering iron onto melt-blown poly(lactide) nonwoven fabrics. The research aimed to thoroughly understand the structure and properties of these materials and their potential applications [...] Read more.
The study investigated the biological properties of a composite material composed of poly(lactide) (PLA) and iron (Fe) produced by sputtering iron onto melt-blown poly(lactide) nonwoven fabrics. The research aimed to thoroughly understand the structure and properties of these materials and their potential applications in biomedicine. We conducted comprehensive chemical and structural analyses using techniques such as microscopic analysis, flame atomic absorption spectrometry (FAAS), and Brunauer–Emmett–Teller (BET) surface area analysis to precisely determine the properties of PLA-Fe materials. Additionally, we evaluated their impact on blood coagulation processes by measuring activated partial thromboplastin time (aPTT) and prothrombin time (PT). We also performed biological analyses on human peripheral blood mononuclear cells (PBM cells) including cell viability and DNA damage. Our results clearly demonstrate that PLA-Fe materials do not significantly influence blood coagulation mechanisms, as they only slightly prolong aPTT time and have no effect on PT. This suggests their potential in biomedical applications. Our results indicate the absence of cyto- and genotoxic properties of PLA-Fe materials against normal blood cells. In conclusion, the research findings suggest that the novel poly(lactide) and iron-sputtered nonwoven fabrics are promising tools in the field of biomedicine, offering potentially innovative therapeutic solutions for the treatment of wounds and injuries. Full article
(This article belongs to the Special Issue Advances in Functional Bio-Coatings)
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14 pages, 7621 KiB  
Article
The Influence of Distance Pulsed Plasma Treatment on the Structure and Properties of Detonation Coatings from Eutectic Alloy Fe-TiB2-CrB2
by Bauyrzhan Rakhadilov, Dauir Kakimzhanov, Ainur Seitkhanova, Aidar Kengesbekov and Nazerke Muktanova
Coatings 2024, 14(8), 1049; https://doi.org/10.3390/coatings14081049 - 16 Aug 2024
Cited by 1 | Viewed by 573
Abstract
This work presents the results of research on the effect of a pulsed plasma treatment on the structure, phase composition, hardness, roughness, and elemental composition of Fe-TiB2-CrB2-based coatings. The Fe-TiB2-CrB2 coating was applied via the detonation [...] Read more.
This work presents the results of research on the effect of a pulsed plasma treatment on the structure, phase composition, hardness, roughness, and elemental composition of Fe-TiB2-CrB2-based coatings. The Fe-TiB2-CrB2 coating was applied via the detonation method. Fe-TiB2-CrB2 powder mixtures were used for coating on AISI 1017 steel substrate with the coating surface being modified using a pulsed plasma treatment. The effects of the pulsed plasma treatment on the microstructure, phase composition, and mechanical properties of Fe-TiB2-CrB2 detonation coatings were investigated using an optical microscope, X-ray diffraction (XRD), scanning electron microscopy (SEM), a nanohardness tester, and a Leica 3D profilometer. The mechanical test results showed that the hardness of the Fe-TiB2-CrB2 coating increased from 8.22 Gpa to 15.6 GPa after the pulsed plasma treatment. The results of the tribological tests show that after the pulsed plasma treatment of Fe-TiB2-CrB2 coatings, a wear-resistant modified layer consisting of (Ti,Cr)B2 and alpha-Fe formed on its surface. It is determined that the surface modified coating layer has a low porosity compared to the coating base. In addition, it is determined that after the pulsed plasma treatment, a decrease in the average pore size is observed in the subsurface layer of the coating. The pulsed plasma treatment resulted in a decrease in the roughness parameter (Ra) from 12.2 μm to 6.6 μm, which is due to the melting of protruding particles. Full article
(This article belongs to the Special Issue The Present Status of Thermally Sprayed Composite Coatings)
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