Coatings

21 pages, 5352 KB

Open AccessArticle

Preparation and Performance of a Photocurable Degradable Waterborne Boron-Containing Polyurethane Acrylate Anti-Fouling Coating

by Jia-Li Yu, Guo-Feng Hu, Jian-Ping Zhou, Hong-Bo Liang, Chun-Hui Zhao and Hui-Ping Xiao

Coatings 2026, 16(3), 393; https://doi.org/10.3390/coatings16030393 - 23 Mar 2026

Viewed by 380

Abstract

Biofouling has a detrimental effect on marine infrastructure and poses a severe challenge to the global marine industry. Therefore, developing efficient and environmentally friendly anti-fouling coatings to protect those facilities has become extremely necessary nowadays. To address marine biofouling, a series of photocurable [...] Read more.

Biofouling has a detrimental effect on marine infrastructure and poses a severe challenge to the global marine industry. Therefore, developing efficient and environmentally friendly anti-fouling coatings to protect those facilities has become extremely necessary nowadays. To address marine biofouling, a series of photocurable degradable waterborne boron-containing polyurethane acrylate (WPU-PTPBx) anti-fouling coatings were prepared by grafting pyridine-triphenylborane (PTPB) onto polyurethane side chains and UV curing. FTIR and ¹H NMR confirmed the successful grafting of PTPB. The WPU-PTPBx aqueous dispersions had a particle size of 30~75 nm with excellent thermal storage stability. DSC and XRD characterizations revealed the amorphous structure of the coatings, which favored biodegradation. All coatings exhibited adhesion strength over 2 MPa, meeting marine application requirements. Antibacterial and anti-algal tests showed that PTPB content positively correlated with anti-fouling performance: the coating achieved a 99.66% inhibition rate against Escherichia coli and reduced the adhesion density of Nitzschia closterium to only 36.9 cells/mm². With favorable degradability and outstanding anti-fouling performance, WPU-PTPBx coatings are promising green anti-fouling materials for marine applications. Full article

(This article belongs to the Special Issue Polymer Coatings: Fundamentals and Applications)

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28 pages, 6219 KB

Open AccessReview

A Review of Laser Welding for Particle-Reinforced Aluminum Matrix Composites and Steel

by Peiyang Fang, Longbo Chen, Yida Zeng, Zhiyong Li, Yan Wang, Guangping Wang, Xin Hong and Longfei Zeng

Coatings 2026, 16(3), 392; https://doi.org/10.3390/coatings16030392 - 23 Mar 2026

Viewed by 335

Abstract

Particle-reinforced aluminum matrix composite (AMC)/steel hybrid structures present considerable benefits for lightweight design and enhanced product performance. This article provides a systematic overview of research advances from 2003 to 2024 on laser welding of particle-reinforced AMCs to steel, with particular emphasis on the [...] Read more.

Particle-reinforced aluminum matrix composite (AMC)/steel hybrid structures present considerable benefits for lightweight design and enhanced product performance. This article provides a systematic overview of research advances from 2003 to 2024 on laser welding of particle-reinforced AMCs to steel, with particular emphasis on the influence of laser welding parameters, shielding gas, and reinforcing particles on the mechanical properties of the welded joints. The mechanisms by which intermetallic compounds (IMCs) impair joint strength are thoroughly analyzed. Moreover, the effects of rare earth element additions on both mechanical properties and corrosion resistance of the joints are critically assessed, along with the coupling mechanism between rare earth elements and the reinforcement phase. Key insights from the literature reveal that regulating heat input can effectively suppress harmful interfacial reactions. Meanwhile, the synergistic incorporation of rare earth elements not only refines the grain structure and boosts mechanical strength, but also improves corrosion resistance through the formation of dense surface oxide films and grain boundary strengthening. This review underscores the innovative integration of interfacial reaction control with rare earth microalloying to achieve high-performance AMC/steel laser-welded joints—a distinct departure from prior studies that typically investigated these strategies separately. Full article

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20 pages, 4094 KB

Open AccessArticle

Tailoring Lithium-Ion Battery Separator Performance Through Cellulose Selection: A Comparative Analysis of Microcrystalline, Nanofibrillated, and Bacterial Cellulose Coatings

by Xinyu Song, Huiling Mo, Anqi Zhou, Bingbing Luo, Zhichong Wang, Yaning Jia, Aimiao Qin, Shiqi Wang, Yinmu Wang and Huihong Xie

Coatings 2026, 16(3), 391; https://doi.org/10.3390/coatings16030391 - 23 Mar 2026

Viewed by 401

Abstract

The inherent hydrophobicity of polyolefin separators significantly impedes rapid electrolyte wetting, thereby limiting the electrochemical performance of lithium-ion batteries. Cellulose, as a hydroxyl-rich natural polymer, serves as an ideal material for enhancing the interface properties of separators. However, there is still a lack [...] Read more.

The inherent hydrophobicity of polyolefin separators significantly impedes rapid electrolyte wetting, thereby limiting the electrochemical performance of lithium-ion batteries. Cellulose, as a hydroxyl-rich natural polymer, serves as an ideal material for enhancing the interface properties of separators. However, there is still a lack of systematic understanding regarding how the morphological structures of cellulose (such as granular, fibrous, or network-like forms) influence the coating structure and ion transport mechanisms. Here, three representative cellulose derivatives—microcrystalline cellulose (MCC), cellulose nanofibers (CNF), and bacterial cellulose (BC)—were selected to construct functionalized polypropylene (PP) composite separators through vacuum filtration. Experimental results demonstrate that all three cellulose coatings reduced contact angles from 50.8° to below 10°, significantly enhancing interfacial affinity. Systematic comparison reveals that cellulose configuration decisively influences separator performance: unlike the dense fiber entanglement networks formed by CNF and BC, the unique rigid granular packing structure of MCC maintains hydrophilicity while establishing more permeable ion transport pathways. Among these, MCC@PP exhibited optimal electrochemical performance, with the lithium-ion migration number increasing to 0.41 and a capacity retention rate of 88.04% after 100 cycles at 0.5 A/g. This study elucidates the relationship between cellulose configuration and the modification of separator performance, demonstrating that MCC represents a more efficient, robust, and cost-effective option for separator modification compared to complex fiber networks. Full article

(This article belongs to the Section Thin Films)

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16 pages, 2591 KB

Open AccessArticle

Experimental and Numerical Study on Discharge Mechanisms of Section Insulators at High Altitude with Structural and Surface Coating Optimization

by Jixing Sun, Yide Liu, Dong Lei, Jiawei Wang, Tong Xing, Kun Zhang and Jiuding Tan

Coatings 2026, 16(3), 390; https://doi.org/10.3390/coatings16030390 - 22 Mar 2026

Viewed by 316

Abstract

With the rapid development of electrified railways in high-altitude regions, section insulators in catenary systems frequently experience gap breakdown and surface flashover under low atmospheric pressure conditions, posing serious threats to safe train operation. This paper investigates the discharge mechanisms of section insulators [...] Read more.

With the rapid development of electrified railways in high-altitude regions, section insulators in catenary systems frequently experience gap breakdown and surface flashover under low atmospheric pressure conditions, posing serious threats to safe train operation. This paper investigates the discharge mechanisms of section insulators in high-altitude environments and conducts research on discharge characteristics under extremely non-uniform electric fields, along with structural optimization. First, the physical mechanisms of gap discharge and surface flashover in section insulators are analyzed. A three-dimensional electric field simulation model of the section insulator is established, and numerical analysis is performed to reveal the electric field distribution characteristics. The results indicate that the electric field is predominantly concentrated at the junction between metal electrodes and insulators, as well as at the tip of the arcing horn. The local maximum field strength reaches 3.84 × 10⁵ V/m, exceeding the corona inception field strength of air, which readily induces discharge. Subsequently, power frequency and lightning impulse discharge tests are conducted in both plain region and regions at an altitude of 4300 m. The results show that under high-altitude conditions, the power frequency breakdown voltage decreases by 28%, and the 50% lightning impulse breakdown voltage decreases by 42%. The discharge voltages under standard atmospheric conditions are obtained through correction. Finally, optimization schemes involving arcing horn structural modification and surface coating application are proposed. Adjusting the arcing horn angle to 55° and adding a grading ring structure with a radius of 70 mm reduces the local maximum field strength by 26%. After applying an RTV insulating coating, the field strength at the junction decreases by 35.9%, effectively enhancing the insulation performance of section insulators in high-altitude regions. Full article

(This article belongs to the Special Issue Advanced Films and Coatings for Energy Storage Materials and Power Insulation Systems)

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24 pages, 9055 KB

Open AccessArticle

Particle Deformation and Energy Redistribution in Laser-Assisted Cold Spray Deposition of 6061 Aluminum Alloy

by Shukai Ge, Qiang Wang, Wenjuan Niu, Nan Li, Liangliang Huang and Nan Guo

Coatings 2026, 16(3), 389; https://doi.org/10.3390/coatings16030389 - 22 Mar 2026

Viewed by 359

Abstract

This study seeks to elucidate the precise modulation of laser-assisted cold spray (LACS) particle deposition and to provide guidance for optimizing process parameters in LACS. While LACS has been shown to improve coating quality, the underlying roles of laser-induced thermal softening in particle [...] Read more.

This study seeks to elucidate the precise modulation of laser-assisted cold spray (LACS) particle deposition and to provide guidance for optimizing process parameters in LACS. While LACS has been shown to improve coating quality, the underlying roles of laser-induced thermal softening in particle deformation, impact energy redistribution, and interfacial bonding of 6061 Al alloy remain unclear. Here, multiscale finite element simulations and experiments were combined to investigate single-particle impact and coating build-up under different laser powers. The results indicate that laser assistance enhances thermal softening, leading to stronger radial spreading, more pronounced jetting, and a larger bonding interface. The simulations show that laser heating expands the thermal softening zone and shifts impact energy dissipation from the particle to the substrate, thereby reducing elastic rebound and promoting stable deposition. TEM analysis confirms dynamic recrystallization at the particle interface under all conditions, while higher laser power broadens the recrystallized region from approximately 0.7 μm to about 1.5 μm and promotes grain growth without causing additional oxidation. Moreover, coating porosity decreases from 3.1% to 1.0% with increasing laser power, whereas nanohardness decreases from 1.43 GPa to 1.24 GPa due to the increased contribution of thermal softening. Overall, the study demonstrates that the beneficial effect of laser assistance originates from thermally activated interfacial localization and energy redistribution, offering a mechanistic framework for optimizing the deposition of difficult-to-deposit aluminum alloys. Full article

(This article belongs to the Special Issue Advancement in Heat Treatment and Surface Modification for Metals, 2nd Edition)

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15 pages, 4234 KB

Open AccessArticle

An In Vitro Investigation of Gas and Dye Leakage at the Implant–Abutment Junction Using Titanium and Cobalt Chrome-Based Abutments

by Amylia Kesha Bal, Terry Richard Walton, Hedi Verena Kruse and Dale Geoffrey Howes

Coatings 2026, 16(3), 388; https://doi.org/10.3390/coatings16030388 - 22 Mar 2026

Viewed by 381

Abstract

The lack of integrity at the implant–abutment junction (IAJ) contributes to problems such as micromovements and microbial colonisation. This study aimed to (1) design a protocol for assessing microleakage at the IAJ using chromophore analysis not previously reported for this specific application, (2) [...] Read more.

The lack of integrity at the implant–abutment junction (IAJ) contributes to problems such as micromovements and microbial colonisation. This study aimed to (1) design a protocol for assessing microleakage at the IAJ using chromophore analysis not previously reported for this specific application, (2) compare gas and dye leakage between titanium (Ti) and cobalt chrome (CoCr) abutments, and (3) assess the effect of gold (Au) gilding on sealing. Forty abutments were divided into five groups: milled Ti (MTi); cast CoCr (CCoCr); milled CoCr (MCoCr); cast CoCr with Au gilding (CCoCrG); and milled CoCr with Au gilding (MCoCrG). Samples were subjected to internal pressure within a gas and dye reservoir. Chromophore analysis via UV-Vis spectrometer was used to calculate crystal violet leakage concentrations. Scanning electron microscopy (SEM) revealed close adaptation in the MTi and MCoCr groups, contrasting with irregularities in the CCoCr groups. Correspondingly, gas leakage and dye leakage were most prevalent in the CCoCr group. Fisher exact test demonstrated a statistically significant difference (p = 0.026) between the MCoCr and CCoCr abutments. While CCoCr exhibited the highest failure rate (62.5%), Au gilding demonstrated a trend toward reduced leakage (25% failure rate), though this did not reach statistical significance (p = 0.315). This chromophore analysis represents a viable and objective assessment of IAJ integrity. Full article

(This article belongs to the Special Issue Surface Engineering of Alloys: Durability and Performance)

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23 pages, 5759 KB

Open AccessArticle

Performance Assessment of Acrylate Metal Complex (AMC) and Conventional Consolidants for Fragile Bone Artefacts

by Di Chen, Liangshuai Zhang, Yuanzhe Mao, Wanling Song and Jiachang Chen

Coatings 2026, 16(3), 387; https://doi.org/10.3390/coatings16030387 - 21 Mar 2026

Viewed by 285

Abstract

Archaeological bone artifacts frequently exhibit diminished mechanical integrity as a result of organic matrix degradation. Under adverse environmental conditions, such artifacts are particularly susceptible to surface cracking and disintegration into powder. It is urgently necessary to develop protective materials that possess high permeability, [...] Read more.

Archaeological bone artifacts frequently exhibit diminished mechanical integrity as a result of organic matrix degradation. Under adverse environmental conditions, such artifacts are particularly susceptible to surface cracking and disintegration into powder. It is urgently necessary to develop protective materials that possess high permeability, strong reinforcing power and good compatibility. This study evaluated the protective performance of a novel Acrylate Metal Complex (AMC) and two conventional commercial consolidants (acrylic resin Paraloid B72 and ethyl silicate-based material Remmers 300) on fragile bone artifacts. Using simulated samples resembling bone artefacts, a systematic evaluation was conducted to assess the penetration, mechanical reinforcement efficacy, microstructural modifications, chromatic impact, and aging resistance of three consolidants. The results indicate that AMC demonstrates optimal permeation capability and can significantly enhance the surface hardness of bone specimens, achieving an increase of 7.7%. The colorimetric changes observed in all three reinforced materials following treatment remained within acceptable limits (ΔE* < 1.5). Accelerated aging tests—including 300 h of UV irradiation and 30 cycles of alternating dry-wet conditions—demonstrated that bone-mimetic composites reinforced with AMC exhibited significantly superior aging resistance relative to those treated with B72 and Remmers 300. In the actual application verification of the archaeological bone relics, the surface hardness of the reinforced AMC increased by 10%, the wave velocity increased by 14.8%, and there was no glare or crust on the surface. Comprehensive comparison shows that AMC outperforms traditional commercial materials in key performance indicators, demonstrating great potential as a next-generation bone relic conservation material. Full article

(This article belongs to the Section Environmental Aspects in Colloid and Interface Science)

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25 pages, 3190 KB

Open AccessReview

High-Temperature Carburization of Gear Steels: Grain Size Regulation, Microstructural Evolution, and Surface Performance Enhancement

by Xiangyu Zhang, Yuxian Cao, Yu Zhang, Dong Pan, Kunyu Wang, Zhihui Li and Leilei Li

Coatings 2026, 16(3), 386; https://doi.org/10.3390/coatings16030386 - 21 Mar 2026

Viewed by 395

Abstract

High-temperature carburization (HTC, 950–1050 °C) has emerged as a pivotal low-carbon, energy-efficient manufacturing technology for gear steels, accelerating carbon diffusion for reducing processing cycles by over 60% while achieving significant energy savings and emission reductions. However, the inherent contradiction between HTC efficiency and [...] Read more.

High-temperature carburization (HTC, 950–1050 °C) has emerged as a pivotal low-carbon, energy-efficient manufacturing technology for gear steels, accelerating carbon diffusion for reducing processing cycles by over 60% while achieving significant energy savings and emission reductions. However, the inherent contradiction between HTC efficiency and microstructural stability, specifically austenite grain coarsening, severely degrades mechanical properties (e.g., strength, toughness, fatigue resistance) and limits widespread application. This review systematically synthesizes recent advances in austenite grain size regulation during HTC of gear steels, focusing on the core scientific framework of “grain coarsening mechanism—regulation strategy—performance enhancement”. It elaborates on thermodynamic and kinetic mechanisms of austenite grain growth, ripening behavior of microalloying precipitates (Nb(C,N), Ti(C,N), AlN, etc.), and their synergistic grain-refining effects. Comprehensive coverage of regulatory strategies (microalloying design, pretreatment technologies, process optimization, and integrated regulation) and characterization techniques is provided, along with a quantitative correlation between grain size, microstructure, and surface performance (wear resistance, corrosion resistance, and fatigue life). Numerical simulation and predictive models (empirical, theoretical, multiphysics coupling, machine learning-based) are critically analyzed, and current challenges (temperature-grain stability trade-off, multifactor synergy understanding, industrial scalability) and future research directions (advanced microalloying systems, intelligent process optimization, cross-scale modeling, green technology integration) are proposed. This review aims to provide theoretical guidance and technical support for optimizing the HTC performance of gear steels, catering to the demands of high-power-density transmission systems in automotive, aerospace, and heavy machinery industries. Full article

(This article belongs to the Special Issue Surface Treatment and Mechanical Properties of Metallic Materials)

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19 pages, 2771 KB

Open AccessArticle

Characterization of Corona-Charged Composite PLA Films as Potential Active Packaging Applications

by Asya Viraneva, Aleksandar Grigorov, Maria Marudova, Temenuzhka Yovcheva and Rumen Mladenov

Coatings 2026, 16(3), 385; https://doi.org/10.3390/coatings16030385 - 21 Mar 2026

Viewed by 256

Abstract

A major drawback of many proposed biobased alternatives of the most commonly used petroleum-based packaging materials is their relatively poor physical properties. In order to develop more viable alternative packaging materials, these properties need to be modified, while maintaining and improving the other [...] Read more.

A major drawback of many proposed biobased alternatives of the most commonly used petroleum-based packaging materials is their relatively poor physical properties. In order to develop more viable alternative packaging materials, these properties need to be modified, while maintaining and improving the other desired characteristics. An investigation was done on corona-charged curcumin-containing PLA films to determine how the addition of the polyphenol impacts its physical properties. Measurements of the surface potential of the films were performed, as was the impact of low pressure on the electret properties. The effect of the corona discharge treatment on the physicochemistry of the surface of composite PLA films was investigated systematically using some complementary surface analytical techniques, such as surface wettability and morphology by scanning electron microscopy. The mechanical properties and conductance of the films were also investigated. A dependency of the decay of the surface potential on the film type and the polarity of the corona was found. It was also established that modifying the surface of the films with corona discharge can cause an increase in their wettability and surface free energy, while also improving their adhesion properties. This is caused by the creation of polar functional groups on the film surface during the charging process. It was also determined that the introduction of curcumin in the PLA films decreases their stiffness, which may be caused by a decrease in intramolecular cohesion. Full article

(This article belongs to the Section Coatings for Food Technology and System)

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18 pages, 3901 KB

Open AccessArticle

Study on the Influence of Sugarcane Bagasse Fiber on the Physical and Mechanical Properties of Lightweight Mortar

by Mo Zhou, Guimeng Ban, Qin Hu, Yuanming Luo, Jintuan Zhang, Tian Su, Zixing Chen, Wenkai Lei, Jingyun Zhang and Tong Han

Coatings 2026, 16(3), 384; https://doi.org/10.3390/coatings16030384 - 20 Mar 2026

Viewed by 318

Abstract

In the context of the “dual-carbon” targets and the development of green building materials, lightweight mortar has attracted considerable attention, owing to its low density and excellent thermal insulation properties. However, lightweight aggregates, such as vitrified microspheres, while effectively reducing mortar density, exhibit [...] Read more.

In the context of the “dual-carbon” targets and the development of green building materials, lightweight mortar has attracted considerable attention, owing to its low density and excellent thermal insulation properties. However, lightweight aggregates, such as vitrified microspheres, while effectively reducing mortar density, exhibit high porosity and weak interfacial bonding, which compromise mechanical performance. To address this issue, this study introduces sugarcane bagasse fiber (SBF) as a reinforcing material, with contents of 0%, 0.4%, 0.8%, 1.2%, and 1.6%. The effects of SBF on physical properties (consistency, density, water absorption) and mechanical properties (compressive strength, flexural strength, and tensile bond strength) were systematically evaluated. Furthermore, low-field nuclear magnetic resonance (LF-NMR) and scanning electron microscopy (SEM) were employed to analyze pore structure and interfacial transition zone (ITZ) characteristics at multiple scales. The results indicate that: (1) at low contents (0.4–0.8%), SBF was uniformly dispersed, improving matrix compactness; (2) compared with the control group, the 28-day compressive, flexural, and tensile bond strengths increased by 7.1%, 13.1%, and 25%, respectively; (3) NMR analysis revealed that the incorporation of SBF significantly increased the proportion of capillary pores, reduced total porosity, and enhanced mortar compactness, thereby improving mechanical strength; (4) fractal dimension analysis showed that contents of 0.4% and 0.8% increased structural complexity while reducing pore connectivity, leading to higher compressive strength; (5) SEM observations further demonstrated that the fibers provided bridging and anchoring effects within the ITZ, promoted the deposition of hydration products, and enhanced interfacial compactness. Full article

(This article belongs to the Section Environmental Aspects in Colloid and Interface Science)

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15 pages, 11372 KB

Open AccessArticle

Microstructure Evolution Mechanism of 4Cr13 Steel During Thermal Deformation

by Junzhao Liu, Zhi Jia, Chi Zhang, Bin Ren, Yanjiang Wang, Zhixin Zhao, Likai Yang and Dekui Mu

Coatings 2026, 16(3), 383; https://doi.org/10.3390/coatings16030383 - 19 Mar 2026

Viewed by 338

Abstract

To investigate the thermal deformation behavior and microstructural evolution of 4Cr13 steel, and to clarify how deformation enhances its microstructure and properties, hot compression tests were conducted on the material at various deformation temperatures (890 °C, 970 °C, 1050 °C, and 1130 °C) [...] Read more.

To investigate the thermal deformation behavior and microstructural evolution of 4Cr13 steel, and to clarify how deformation enhances its microstructure and properties, hot compression tests were conducted on the material at various deformation temperatures (890 °C, 970 °C, 1050 °C, and 1130 °C) and strain rates (0.1 s⁻¹ and 10 s⁻¹), followed by spheroidizing annealing. The results indicate that thermal deformation significantly refines the final microstructure and improves material properties. With increasing deformation temperature, the carbide count decreases, and recrystallization becomes more extensive. At a deformation temperature of 1130 °C and a strain rate of 10 s⁻¹, the microhardness of the specimen reached a maximum value of 738.85 HV. Furthermore, the thermal deformation process stores considerable strain energy in the material, which acts as the driving force for static recovery and recrystallization during annealing. This promotes the development of a spheroidized, equiaxed grain structure free from distortions, thereby reducing the influence of the microstructural inheritance effect on the martensitic structure after annealing. Full article

(This article belongs to the Special Issue Advanced Manufacturing for Architected Materials and Multifunctional Coatings)

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4 pages, 148 KB

Open AccessEditorial

Edible Films and Coatings with Tailored Features for Improvement of Food Quality

by Giuseppe Sortino

Coatings 2026, 16(3), 382; https://doi.org/10.3390/coatings16030382 - 19 Mar 2026

Viewed by 304

Abstract

The interest in edible films and coatings has rapidly increased in recent years, driven by the need for fresher and safer foods and the growing attention toward sustainable solutions capable of reducing the use of chemical postharvest treatments [...] Full article

(This article belongs to the Special Issue Edible Films and Coatings with Tailored Features for Improvement of Food Quality)

27 pages, 19830 KB

Open AccessArticle

Effect of Spraying Distance on the Scratch Wear Behavior of 8YSZ and Gd-Yb-Y Co-Doped ZrO₂ TBCs

by Ali Haydar Güneş, Sinan Fidan, Şaban Hakan Atapek, Mustafa Özgür Bora, Satılmış Ürgün, Mehmet İskender Özsoy, Sedat İriç and Tuğçe Yayla Yazıcı

Coatings 2026, 16(3), 381; https://doi.org/10.3390/coatings16030381 - 19 Mar 2026

Viewed by 391

Abstract

This study investigates how torch standoff distance influences the microstructure, surface topography, and progressive-load scratch response of air plasma-sprayed 8YSZ and rare-earth co-doped GdYbYSZ thermal barrier coatings on an St-52 grade carbon steel substrate. Three nozzle-to-substrate spraying distances were examined: 80, 100, and [...] Read more.

This study investigates how torch standoff distance influences the microstructure, surface topography, and progressive-load scratch response of air plasma-sprayed 8YSZ and rare-earth co-doped GdYbYSZ thermal barrier coatings on an St-52 grade carbon steel substrate. Three nozzle-to-substrate spraying distances were examined: 80, 100, and 120 mm. X-ray diffraction revealed that the 8YSZ coatings possessed a predominantly tetragonal (t′) structure, with minor monoclinic fractions detected in the coatings obtained with the 80 mm and 100 mm distance parameters. The GdYbYSZ coatings, in contrast, exhibited a single-phase cubic defect-fluorite structure; their diffraction peaks appeared at lower 2θ angles relative to undoped cubic ZrO₂, consistent with lattice expansion caused by the substitution of Zr⁴⁺ by the larger Gd³⁺ and Yb³⁺ cations. Surface topography was quantified by non-contact laser profilometry, providing areal (Sa) and profile (Ra) roughness parameters for the as-sprayed condition as well as three-dimensional scratch-damage morphology after testing. Progressive-load scratch tests were performed using a Rockwell diamond indenter over a 2 mm track with the normal load ramped from 0.03 N to 30 N. Penetration depth, residual depth, tangential force, and acoustic emission were recorded continuously to identify critical damage transitions. Across all spraying distances, 8YSZ exhibited systematically shallower scratch grooves than GdYbYSZ; end-of-track maximum groove depths remained below 37 µm for 8YSZ, whereas GdYbYSZ reached up to 72 µm under identical loading conditions. The novelty of this study lies in combining torch standoff distance as a processing variable with multi-channel progressive-load scratch diagnostics, including in situ acoustic emission, depth profiling, and friction monitoring, to comparatively assess the scratch wear performance of 8YSZ and rare-earth co-doped zirconia TBCs for the first time. Full article

(This article belongs to the Section Ceramic Coatings and Engineering Technology)

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11 pages, 2357 KB

Open AccessArticle

Optimization of Hot Forming Process Parameters of 7050 Aluminum Alloy Based on TOPSIS and EWM

by Guosheng Fei, Xiaoci Chen, Daijian Wu and Zuofa Liu

Coatings 2026, 16(3), 380; https://doi.org/10.3390/coatings16030380 - 19 Mar 2026

Viewed by 338

Abstract

To accurately control the hot workability of 7050 aluminum alloy and determine the optimal process window, systematic hot compression experiments were carried out on the Gleeble-3500 thermal simulation test machine under the multi-group process conditions of deformation temperature 300~450 °C, strain rate 0.001~1 [...] Read more.

To accurately control the hot workability of 7050 aluminum alloy and determine the optimal process window, systematic hot compression experiments were carried out on the Gleeble-3500 thermal simulation test machine under the multi-group process conditions of deformation temperature 300~450 °C, strain rate 0.001~1 s⁻¹, and maximum deformation of 60%. The high-temperature rheological curve data were collected, and the key hot deformation parameters, such as deformation activation energy Q, Zener–Hollomon (Z) parameter, and power dissipation efficiency η, were calculated based on the experimental results. The random forest prediction model between process parameters and thermal deformation parameters was innovatively constructed to realize the accurate quantification of the parameter relationship. On this basis, the multi-objective process optimization was further carried out by coupling the TOPSIS and EWMs. Finally, the optimal hot deformation process parameters of 7050 aluminum alloy were determined as 410~450 °C and 0.001~1 s⁻¹. The microstructure analysis showed that the main deformation mechanism of the material in the optimized region was dynamic recrystallization, which could effectively ensure the microstructure uniformity and mechanical property stability of the formed parts. Full article

(This article belongs to the Special Issue Advanced High Entropy Alloy Materials and Films: Properties and Applications)

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14 pages, 5819 KB

Open AccessArticle

HMDSO-Based Plasma Coatings for Modifying Metallic Surfaces for Hydrophobic Applications

by Elmar Moritzer, Dennis Rauen and Justin Hoppe

Coatings 2026, 16(3), 379; https://doi.org/10.3390/coatings16030379 - 18 Mar 2026

Viewed by 301

Abstract

This study investigates the hydrophobic properties of hexamethyldisiloxane (HMDSO)-based coatings deposited by atmospheric pressure plasma-enhanced chemical vapor deposition (AP-PECVD). The objective of this procedure is to enable the extraction of molded components from the mold cavity. The test specimen geometry employed in the [...] Read more.

This study investigates the hydrophobic properties of hexamethyldisiloxane (HMDSO)-based coatings deposited by atmospheric pressure plasma-enhanced chemical vapor deposition (AP-PECVD). The objective of this procedure is to enable the extraction of molded components from the mold cavity. The test specimen geometry employed in the present investigation were made of tool steel 1.2311, a material that is frequently utilized in industrial applications. A series of experiments was conducted to assess the coating performance. Initially, surface energy measurements based on contact angle analysis were performed to determine the polar and dispersive surface components. Finally, energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscope (SEM) images are used to perform an exact measurement of the elemental composition and an optical comparison of the surface. The results of the work indicate that the material composition on the surface of silicon and oxygen is of particular importance. In addition, the results indicate that the use of argon as a carrier gas has a positive effect on reducing surface energy and increasing the contact angle to water drops. Full article

(This article belongs to the Special Issue Advanced Plasma Surface Treatments and Their Applications in Coating Technologies)

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15 pages, 4064 KB

Open AccessFeature PaperArticle

Study on the Interlayer Contact Mechanism of Foamed Cold-Recycled Asphalt Mixture Under Static Loads

by Han Zhao, Jiangyu Liu and Junyan Yi

Coatings 2026, 16(3), 378; https://doi.org/10.3390/coatings16030378 - 17 Mar 2026

Viewed by 332

Abstract

To investigate the interlayer contact mechanism of foamed cold-recycled asphalt mixture under static loads, a three-layer asphalt pavement discrete element model (DEM) was established, with the surface layer composed of asphalt concrete-13 (AC-13), asphalt concrete-20 (AC-20) and asphalt-treated base-25 (ATB-25) foamed cold-recycled asphalt [...] Read more.

To investigate the interlayer contact mechanism of foamed cold-recycled asphalt mixture under static loads, a three-layer asphalt pavement discrete element model (DEM) was established, with the surface layer composed of asphalt concrete-13 (AC-13), asphalt concrete-20 (AC-20) and asphalt-treated base-25 (ATB-25) foamed cold-recycled asphalt mixture and cement-stabilized macadam as the base. Based on mortar theory, the pavement was divided into coarse aggregate, asphalt mastic and air void phases, and the Burgers Model, Linear Parallel Bond Model and Linear Model were adopted to characterize the bonding of asphalt-aggregate, cement contact interface and subgrade-surface layer, respectively. Static loads of 0.7 MPa, 1.1 MPa, 1.5 MPa and 1.9 MPa were applied to analyze the mechanical responses of asphalt-based and cement-based pavement systems from tensile strain, vertical compressive stress and vertical displacement. Results showed that mechanical indices of the pavement increase monotonically with static load and present obvious layered distribution. The cement-stabilized macadam base provides rigid support, significantly reducing tensile strain (TS) and vertical displacement (VD) of asphalt layers, while the asphalt-based system has flexible stress transfer and superior stress dissipation in the bottom layer. The two systems exhibit respective structural advantages, with the cement-based system outstanding in deformation control and the asphalt-based system suitable for flexible stress adaptation working conditions. Full article

(This article belongs to the Special Issue Surface Treatment and Mechanical Properties of Sustainable Pavement Materials, 2nd Edition)

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28 pages, 6829 KB

Open AccessArticle

Numerical Simulation of Particle Deposition on Superhydrophobic Surfaces with Randomly Distributed Roughness—A Coupled LBM-IMBM-DEM Method

by Wenjun Zhao and Hao Lu

Coatings 2026, 16(3), 377; https://doi.org/10.3390/coatings16030377 - 17 Mar 2026

Viewed by 440

Abstract

Dust pollution has emerged as a critical issue in a wide range of industrial applications, creating an urgent demand for effective strategies to mitigate particle deposition. Recent experimental studies have demonstrated that superhydrophobic coatings represent a promising class of self-cleaning materials, primarily attributed [...] Read more.

Dust pollution has emerged as a critical issue in a wide range of industrial applications, creating an urgent demand for effective strategies to mitigate particle deposition. Recent experimental studies have demonstrated that superhydrophobic coatings represent a promising class of self-cleaning materials, primarily attributed to their hierarchical rough structures and intrinsically low surface energy. Nevertheless, the underlying self-cleaning mechanisms of superhydrophobic surfaces have not yet been fully elucidated. This work examines particle deposition on superhydrophobic surfaces featuring stochastic roughness distributions through computational modeling. Surface topographies were generated using Fast Fourier Transform techniques. An integrated lattice Boltzmann–discrete element method (LBM–DEM) framework simulated particle transport in superhydrophobic-coated channels. Particle–fluid coupling was achieved via the immersed moving boundary approach, while particle–surface interactions employed a modified Johnson–Kendall–Roberts (JKR) adhesion model. Parametric studies quantified effects of particle size, interfacial energy, flow Reynolds number, and topographical statistics on deposition dynamics. Experimental validation demonstrates good agreement between numerical predictions and measurements. Smaller particles exhibit a lower tendency to deposit on superhydrophobic surfaces, whereas increasing surface energy significantly enhances particle deposition due to stronger adhesion forces and the suppression of particle resuspension. In addition, higher Reynolds numbers effectively reduce particle deposition. The revealed self-cleaning mechanisms provide theoretical guidance for the design of high-performance self-cleaning coatings, and the identified effects of particle and surface parameters offer practical insights for anti-pollution engineering applications. Full article

(This article belongs to the Section Surface Engineering for Energy Harvesting, Conversion, and Storage)

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14 pages, 3902 KB

Open AccessArticle

Influence of Oxygen Flow and Stoichiometry on Optical Properties and Damage Resistance of Hafnium Oxide Thin Films

by Amira Guediche, Saaxewer Diop, Raluca A. Negres, Leonardus Bimo Bayu Aji and Colin Harthcock

Coatings 2026, 16(3), 376; https://doi.org/10.3390/coatings16030376 - 17 Mar 2026

Viewed by 413

Abstract

Hafnium oxide (HfO₂) is predominantly used as a high-index material in multi-layer dielectric coatings for high-peak- and high-average-power lasers, but laser damage often initiates within the HfO₂ layers despite their wide bandgap. Oxygen deficiency during deposition can introduce vacancy-related sub-bandgap [...] Read more.

Hafnium oxide (HfO₂) is predominantly used as a high-index material in multi-layer dielectric coatings for high-peak- and high-average-power lasers, but laser damage often initiates within the HfO₂ layers despite their wide bandgap. Oxygen deficiency during deposition can introduce vacancy-related sub-bandgap states and absorptive defects, lowering damage resistance. This study investigates how oxygen flow during HfO₂ deposition with ion beam sputtering (IBS) affects its stoichiometry, defect formation, and nanosecond laser-induced damage threshold (LIDT) and whether single-layer trends predict multilayer performance. Single layers were deposited at varying oxygen flows, characterized for optical and structural properties, and tested for the LIDT at 1064 nm and 355 nm. Increasing oxygen flow drove the layer toward near-stoichiometric HfO₂, reduced the refractive index, and altered the density of surface pinhole-like features. The single-layer LIDT at 355 nm increased with oxygen, whereas the 1064 nm LIDT was comparatively less sensitive to oxygen flow, consistent with the wavelength-dependent roles of absorptive precursors and microstructural defects. In contrast, a HfO₂-based high-reflector (HR) showed a higher LIDT at lower oxygen flow, indicating that the family of damage precursors changes between single layers and multilayers; in stacks, structural properties such as stress, gas entrapment and thermal dissipation may outweigh the isolated absorptive defects found in single layers. These results demonstrate that the optimal oxygen flow condition depends on both LIDT wavelength and film architecture. We identified, for single layers, a 15–35 sccm window for maximizing the 1064 nm LIDT and a high-flow optimum (45 sccm) for the 355 nm LIDT and, for 355 nm HR stacks, a distinct lower-flow regime (~10 sccm). Full article

(This article belongs to the Topic Advanced Manufacturing and Surface Technology, 2nd Edition)

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17 pages, 4059 KB

Open AccessArticle

Facile Elaboration of TiO₂-ZnO-Based Low-Cost H₂ Gas Sensors

by Ali Faddouli, Youssef Nouri, Bouchaib Hartiti, Youssef Doubi, Mehmet Ertugrul, Ömer Çoban and Hicham Labrim

Coatings 2026, 16(3), 375; https://doi.org/10.3390/coatings16030375 - 17 Mar 2026

Viewed by 387

Abstract

This study presents the development of a low-cost H₂ gas sensor made from a titanium dioxide–zinc oxide composite by means of a simple, cost-effective screen-printing method. The sensing material was created by mixing titanium dioxide and zinc oxide nanoparticles with an organic [...] Read more.

This study presents the development of a low-cost H₂ gas sensor made from a titanium dioxide–zinc oxide composite by means of a simple, cost-effective screen-printing method. The sensing material was created by mixing titanium dioxide and zinc oxide nanoparticles with an organic binder, which was screen-printed onto a glass substrate containing silver electrodes. These samples were then characterized using X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM). The XRD results confirmed that the films boasted well-defined crystallinity, with predominant anatase and hexagonal ZnO phases, as well as uniformity of grains. Sensor performance was evaluated in a custom-built chamber at hydrogen concentrations of 100 to 1000 ppm and at operating temperatures of 100 °C, 200 °C, and 300 °C. The results indicate improved sensor performance as the operating temperature increased to 300 °C, with the best sensitivity values of 0.99, 1.17, and 1.31 at hydrogen concentrations of 100, 500, and 1000 ppm, respectively. The sensor showed stable and reproducible response characteristics, and its responses were retimed after a few hundred seconds. Low-cost fabrication, ease of processing, and reliable sensor performance make titanium oxide–zinc oxide composites promising candidates for hydrogen detection. Full article

(This article belongs to the Special Issue Advanced Materials, Thin Films, and Functional Coatings for Gas Sensing and Optoelectronic Applications)

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27 pages, 9906 KB

Open AccessArticle

Structural Behavior and Performance Assessment of a Prestressed Aluminum Alloy Formwork System for Large-Span Concrete Domes

by Lingling Ren, Yuan Liu, Xingpeng Ma, Zehao Li and Dongsheng Lei

Coatings 2026, 16(3), 374; https://doi.org/10.3390/coatings16030374 - 17 Mar 2026

Viewed by 354

Abstract

To overcome the limitations of conventional steel support systems in large-span concrete dome construction, this study proposes a novel prestressed modular aluminum alloy formwork system based on a radial–circumferential spatial truss configuration. A refined finite element model was established to simulate the staged [...] Read more.

To overcome the limitations of conventional steel support systems in large-span concrete dome construction, this study proposes a novel prestressed modular aluminum alloy formwork system based on a radial–circumferential spatial truss configuration. A refined finite element model was established to simulate the staged construction process under the most unfavorable load combination (1.3G + 1.5Q), and the influences of prestress levels and concrete pouring sequences were systematically investigated. Results indicate that external prestressing significantly enhances structural stiffness and deformation control. Increasing the prestress level from 0.3fptk to 0.5fptk reduces the maximum vertical displacement by approximately 18%, while a prestress of 0.7fptk achieves a total reduction of about 31%. Radial support displacement decreases by up to 48%, demonstrating improved global stability. Considering both deformation control and material utilization efficiency, 0.5fptk is recommended as the optimal prestress level. Comparative analysis of construction schemes shows that the layered pouring method reduces maximum vertical displacement by approximately 15% compared with ring casting. Buckling analyses further confirm adequate stability reserve beyond code-required safety coefficients. These findings verify the feasibility and deformation control effectiveness of the proposed prestressed aluminum alloy dome formwork system for large-span construction applications. Full article

(This article belongs to the Special Issue Latest Insights in Metal Fatigue, Failure, and Fracture)

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20 pages, 5515 KB

Open AccessArticle

CoastCor-Net: A Wind Turbine Blade Defect Detection Network for Coastal Environments

by Jiawei Xiang, Xinyu Wan and Shoudong Ni

Coatings 2026, 16(3), 373; https://doi.org/10.3390/coatings16030373 - 16 Mar 2026

Viewed by 385

Abstract

Coastal wind turbines operate under severe salt spray, high humidity, and wind-driven erosion, which accelerate coating degradation and corrosion-induced cracking. In such environments, corrosion defects exhibit blurred boundaries, weak textures, and significant scale variations, challenging object detectors in small-target localization and precise boundary [...] Read more.

Coastal wind turbines operate under severe salt spray, high humidity, and wind-driven erosion, which accelerate coating degradation and corrosion-induced cracking. In such environments, corrosion defects exhibit blurred boundaries, weak textures, and significant scale variations, challenging object detectors in small-target localization and precise boundary regression. To address these limitations, this study proposes CoastCor-Net, an enhanced YOLOv11-based framework that improves spatial–semantic alignment, boundary representation, and channel–spatial dependency modeling. The architecture integrates three complementary modules to enhance boundary sensitivity, spatial–semantic consistency, and cross-channel interaction: a Decoding-Driven Enhancement Block, a Complementary Feature Alignment Module, and a Channel-Transposed Coordinate Attention module. Extensive experiments on the Wind Turbine Blade Damage Dataset show that CoastCor-Net achieves 84.7% mAP@0.5 and 54.1% mAP@0.5:0.95, surpassing YOLOv13n by 3.2 percentage points in mAP@0.5 and improving AP_damage by 5.2 percentage points. The framework also demonstrates strong robustness under composite coastal perturbations. These findings highlight the practical effectiveness of structured multi-level feature enhancement for reliable and high-precision blade inspection in complex coastal environments. Full article

(This article belongs to the Special Issue Corrosion Characteristics and Surface Protection of Coastal Infrastructure)

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16 pages, 5535 KB

Open AccessArticle

Enhancing the Properties of As-Cast Al6061 Composites with Ti₃C₂T_x Reinforcement: Grain Refinement, Strength Improvement, and Self-Lubricating Wear Behavior

by Zhibin Liu, Wenjie Hu and Hong Yan

Coatings 2026, 16(3), 372; https://doi.org/10.3390/coatings16030372 - 15 Mar 2026

Viewed by 342

Abstract

Ti₃C₂T_x/Al6061 composites were fabricated via vacuum induction melting, with systematic analysis conducted on their microstructure, mechanical properties, and wear behavior. Findings indicate that Ti₃C₂T_x addition significantly refined the composite grain size. Uniformly [...] Read more.

Ti₃C₂T_x/Al6061 composites were fabricated via vacuum induction melting, with systematic analysis conducted on their microstructure, mechanical properties, and wear behavior. Findings indicate that Ti₃C₂T_x addition significantly refined the composite grain size. Uniformly dispersed Ti₃C₂T_x particles promoted heterogeneous nucleation, reducing the average grain size by 44.7% compared to the matrix at the optimal 2 wt.% addition. Strong interfacial bonding ensured efficient load transfer, resulting in a 48.4% increase in tensile strength for the 2 wt.% Ti₃C₂T_x/Al6061 composites compared to the matrix alloy, while elongation decreased by 11.7%. Tribological analysis revealed that the wear rate of 2 wt.% Ti₃C₂T_x/Al6061 composites increases with applied load but remained substantially lower than Al6061 under all tested conditions. This excellent wear resistance is attributed to the synergistic effect of the protective mechanically mixed-layers formation and the inherent self-lubrication property of Ti₃C₂T_x during sliding contact. With increasing load, the friction coefficient and tendency for microcracking on the worn surface of the composite increased, and the dominant wear mechanisms transitioned from abrasive and adhesive wear to delamination wear. Full article

(This article belongs to the Special Issue Advanced Tribological Coatings: Fabrication and Application)

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17 pages, 4672 KB

Open AccessArticle

Numerical Simulation and Experimental Study on Liquid-Filling Forming of 2A12 Aluminum Alloy Fairing

by Yougen Dong, Xuefeng Xu, Yuehui Chen and Yubin Fan

Coatings 2026, 16(3), 371; https://doi.org/10.3390/coatings16030371 - 15 Mar 2026

Viewed by 357

Abstract

To address the challenges of excessive local thinning, poor surface quality, and low production efficiency in traditional multi-pass deep-drawn aluminum alloy fairings, this study investigates the effects of process parameters—including liquid chamber pressure, holding force, and differentiated lubrication schemes—on the liquid-filled forming performance [...] Read more.

To address the challenges of excessive local thinning, poor surface quality, and low production efficiency in traditional multi-pass deep-drawn aluminum alloy fairings, this study investigates the effects of process parameters—including liquid chamber pressure, holding force, and differentiated lubrication schemes—on the liquid-filled forming performance and wall thickness distribution of a 460 × 280 × 1.5 mm thin-walled 2A12 aluminum alloy fairing. Employing an integrated liquid-filled forming technique combining a flexible punch with a rigid die, the research combines numerical simulation with experimental validation. The study demonstrates good consistency between experimental results and numerical simulations. The optimal forming process parameters are liquid chamber pressure of 10 MPa, holding force of 1100 kN, and a lubrication scheme (friction coefficients of 0.01 for the flange and forming zones and 0.06 for the transition radius zone). Under these parameters, part wrinkling and cracking are effectively suppressed, achieving optimal wall thickness uniformity in the formed parts, with a maximum thinning rate of only 6.6%. The proposed liquid-assisted forming process and differentiated lubrication scheme provide a new technical pathway for high-precision manufacturing of thin-walled complex curved components made of 2A12 aluminum alloy. Compared to traditional multi-stage drawing processes, both forming efficiency and quality are significantly improved. Full article

(This article belongs to the Special Issue Advances in Metal Additive Manufacturing Technique: Processes and Novel Materials)

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28 pages, 21159 KB

Open AccessArticle

Defect Evolution, Texture Modification, and T6 Response of LPBF AA7075 Reinforced with AlCoCrFeNi_2.1 Eutectic HEA Particles

by Qiongqi Xu, Baljit Singh Bhathal Singh, Yi Zhang, Mohd Shahriman Adenan, Shengcong Zeng and Shixi Gan

Coatings 2026, 16(3), 370; https://doi.org/10.3390/coatings16030370 - 15 Mar 2026

Cited by 1 | Viewed by 415

Abstract

Laser powder bed fusion (LPBF) of AA7075 is severely constrained by a narrow process window and susceptibility to defect formation (hot cracking and porosity), which often dominates performance. In this study, 5 wt.% AlCoCrFeNi_2.1 high-entropy alloy (HEA) particles, volumetric energy density (VED [...] Read more.

Laser powder bed fusion (LPBF) of AA7075 is severely constrained by a narrow process window and susceptibility to defect formation (hot cracking and porosity), which often dominates performance. In this study, 5 wt.% AlCoCrFeNi_2.1 high-entropy alloy (HEA) particles, volumetric energy density (VED = 74–222 J·mm⁻³), and subsequent T6 heat treatment were systematically investigated to reveal their combined effects on defect structure, crystallographic texture/substructure, and tensile behaviour. Quantitative EBSD shows a measurable grain refinement in the as-built state (average grain size 13.44 → 11.80 µm, ~12%) accompanied by a pronounced weakening of the <001> fibre texture (maximum MRD 4.94 → 2.38), indicating disrupted epitaxial growth and a more dispersed orientation distribution. After T6, the reinforced alloy retains a higher low-angle boundary fraction (31.62% vs. 24.17% in unreinforced AA7075) and a higher kernel average misorientation (0.80° vs. 0.60°), consistent with particle-stabilised substructure retention and retarded recovery. Across all VEDs, AA7075-HEA exhibits higher microhardness (compared with AA7075, the addition of HEA increases the hardness by roughly 20–50 HV) and tensile strength, with the intermediate VED (140.74 J·mm⁻³, T6 states) yielding the best performance. While macroscopic cracking is not fully eliminated, the results clarify that HEA-enabled texture/substructure modifications can contribute to enhanced defect tolerance and are more effectively translated into tensile performance when the as-built defect severity is controlled. These findings provide quantitative insights into defect–microstructure–property coupling in LPBF AA7075-HEA composites from as-built to T6 states. Full article

(This article belongs to the Special Issue Innovations, Applications and Advances of High-Entropy Alloy Coatings)

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17 pages, 17553 KB

Open AccessArticle

Study on the Self-Healing Performance of Microcapsule-Modified Recycled Asphalt Mixtures

by Bosong Jia, Guangqing Yang, Qiaoyi Li and Xinwen Zhang

Coatings 2026, 16(3), 369; https://doi.org/10.3390/coatings16030369 - 14 Mar 2026

Viewed by 316

Abstract

The incorporation of reclaimed asphalt pavement (RAP) in asphalt mixtures improves sustainability but significantly reduces the intrinsic self-healing capacity due to binder aging. This study aimed to quantify whether epoxy-coated rejuvenator microcapsules could restore and enhance the self-healing performance of RAP-containing recycled asphalt [...] Read more.

The incorporation of reclaimed asphalt pavement (RAP) in asphalt mixtures improves sustainability but significantly reduces the intrinsic self-healing capacity due to binder aging. This study aimed to quantify whether epoxy-coated rejuvenator microcapsules could restore and enhance the self-healing performance of RAP-containing recycled asphalt mixtures. Four mixture types (AC-10C, AC-13C, AC-16C, and SMA-13C) containing 20% RAP were evaluated using a fracture–healing–refracture bending test (Repair index, R_C) and a splitting healing strength ratio (S_HSR) test to determine the effects of healing time, temperature, and microcapsule dosage. R_C increased rapidly during the first 8 h of healing and then approached stabilization, with the growth rate falling below 2%, indicating 8 h as the practical optimum healing duration. R_C increased from 0 °C to 45 °C due to enhanced binder mobility and diffusion, and slightly decreased at 60 °C because temperature-induced softening reduced peak bending strength. The highest self-healing capacity was obtained at a microcapsule dosage of 4% (by RAP mass). Under the optimum healing condition (8 h and 45 °C), R_C increased by 10.38%–13.50% and S_HSR increased by 14.35%–25.27% compared with mixtures without microcapsules. Among the mixtures, SMA-13C exhibited the highest self-healing capacity, followed by AC-13C, AC-10C, and AC-16C. The contribution of this study lies in quantifying the healing enhancement in RAP-containing mixtures, identifying practical optimum healing conditions based on a growth-rate criterion, and demonstrating consistent trends between two healing indices across different mixture structures. Full article

(This article belongs to the Section Environmental Aspects in Colloid and Interface Science)

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13 pages, 2806 KB

Open AccessArticle

Turning Waste into Value: An Eco-Friendly Coating Derived from Magnesium Slag for Oxidation Protection of Mechanical Components During Heat Treatment

by Yuanyuan Liang, Zhihe Dou and Tingan Zhang

Coatings 2026, 16(3), 368; https://doi.org/10.3390/coatings16030368 - 14 Mar 2026

Viewed by 266

Abstract

The performance improvement of mechanical components often relies on heat treatment processes, but these processes inevitably result in oxidation burn-off. The repeated formation and spallation of Fe₂O₃ rich oxide scales lead to substantial iron depletion and surface deterioration. Consequently, environmentally [...] Read more.

The performance improvement of mechanical components often relies on heat treatment processes, but these processes inevitably result in oxidation burn-off. The repeated formation and spallation of Fe₂O₃ rich oxide scales lead to substantial iron depletion and surface deterioration. Consequently, environmentally sustainable and economically viable protective coatings are required to suppress oxidation induced burn off. In this work, a TiO₂-MgAl₂O₄ composite coating was synthesized from magnesium slag and applied to Q235 carbon steel to enhance its performance during prolonged high temperature heat treatment. Oxidation tests conducted at 900 °C for 60 min demonstrated that the coating markedly improved the oxidation resistance of carbon steel, with an enhancement of approximately 87% relative to the uncoated specimens. To elucidate the protective mechanism, SEM-EDS, XRD, TG-DSC, and XPS analyses were employed. Based on Wagner Theory, the formation of interfacial phases such as Mg_7.92Al_15.31Fe_0.66O₃₂, which effectively impeded oxygen ion diffusion and thereby enhanced the oxidation resistance during high-temperature exposure. Furthermore, the synergistic effect of aluminum-, magnesium-, and titanium-containing compounds in the coating contributed to suppressing the diffusion of oxygen and iron ions, thus further improving the protective performance. This study provides a systematic theoretical foundation and practical guidance for addressing material loss during high-temperature processing of mechanical components, as well as for promoting the resource utilization of magnesium slag. Full article

(This article belongs to the Special Issue Advances in Corrosion, Oxidation, and/or Wear-Resistant Coatings)

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11 pages, 5930 KB

Open AccessFeature PaperArticle

Electrochemical Corrosion Behavior of Cold-Sprayed Cr₂AlC Coating on H13 Steel in 3.5 wt.% NaCl Solution

by Xuejin Zhang, Shibo Li, Weiwei Zhang, Shengshu Zuo, Yixiong Zhang and Yage Meng

Coatings 2026, 16(3), 367; https://doi.org/10.3390/coatings16030367 - 13 Mar 2026

Viewed by 274

Abstract

A cold-sprayed Cr₂AlC coating was deposited on an H13 tool steel substrate, and the electrochemical corrosion behavior in 3.5 wt.% NaCl solution was experimentally investigated. Electrochemical tests, including open circuit potential and potentiodynamic polarization measurements, revealed that the Cr₂AlC [...] Read more.

A cold-sprayed Cr₂AlC coating was deposited on an H13 tool steel substrate, and the electrochemical corrosion behavior in 3.5 wt.% NaCl solution was experimentally investigated. Electrochemical tests, including open circuit potential and potentiodynamic polarization measurements, revealed that the Cr₂AlC coating significantly improved the corrosion resistance of H13 steel, exhibiting a more positive open circuit potential and a reduced corrosion current density compared with the bare H13 steel substrate. Post-corrosion surface morphology analysis by scanning electron microscopy showed extensive pitting corrosion on the substrate surface, while no obvious corrosion damage was observed on the coating surface. X-ray photoelectron spectroscopy (XPS) analysis further confirmed the formation of a passive film composed of chromium and aluminum oxides on the coating surface, indicating a protective passivation mechanism. The enhanced corrosion performance is attributed to a synergistic mechanism involving both a physical barrier provided by the coating and surface passivation induced by the Cr/Al-based oxide layer. This work highlights the potential of cold-sprayed Cr₂AlC coating as an effective corrosion protection solution for steel substrates in chloride-containing environments. Full article

(This article belongs to the Special Issue Cold-Spray Coatings: Microstructure, Mechanical Properties and Applications)

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20 pages, 11198 KB

Open AccessArticle

A Laser-Engineered Architecture for a Thermally Switchable Slippery Surface with Durable Anti-Corrosion and Self-Healing Properties

by Zexu Zhao, Guoyun Luo, Yuchao Li and Lijun Song

Coatings 2026, 16(3), 366; https://doi.org/10.3390/coatings16030366 - 13 Mar 2026

Viewed by 313

Abstract

Slippery lubricant-infused surfaces (SLIPS) suffer from rapid lubricant depletion, severely limiting their durability in practical applications. To overcome this, we propose a laser-engineered hierarchical architecture that physically locks a solid paraffin lubricant, creating a multifunctional coating with thermally switchable slipperiness. Using femtosecond laser [...] Read more.

Slippery lubricant-infused surfaces (SLIPS) suffer from rapid lubricant depletion, severely limiting their durability in practical applications. To overcome this, we propose a laser-engineered hierarchical architecture that physically locks a solid paraffin lubricant, creating a multifunctional coating with thermally switchable slipperiness. Using femtosecond laser ablation, a hierarchical porous structure (HPS) was fabricated on an aluminum alloy, followed by silanization to achieve superhydrophobicity (contact angle ≈ 154.7°) for enhanced paraffin wetting. The resulting HPS-P coating exhibits thermally switchable adhesion: water droplets pin on the solid surface (sliding angle > 90°) but slide readily (<10°) upon heating above the paraffin’s melting point. The coating demonstrates rapid self-healing, repairing severe scratches within 100 s via molten paraffin flow. The HPS-P coating provides excellent corrosion protection, with its corrosion current density reduced by six orders of magnitude compared to bare aluminum and an inhibition efficiency approaching 100%. This work provides a durable, thermally responsive coating strategy with integrated anti-corrosion and self-healing functions for extreme environments. Full article

(This article belongs to the Section Corrosion, Wear and Erosion)

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17 pages, 4231 KB

Open AccessArticle

Electrodeposition of Ni–Fe Thin Films: Effect of Electrolyte Composition and Current Density on Structure, Morphology and Magnetic Properties

by Vasil Kostov, Boriana Tzaneva, Olena Okhay, Georgi Avdeev and Mihaela Georgieva

Coatings 2026, 16(3), 365; https://doi.org/10.3390/coatings16030365 - 13 Mar 2026

Viewed by 393

Abstract

In the present study, the electrodeposition of thin Ni–Fe films obtained from aqueous electrolytes containing nickel (II) and iron (II) sulfates and chlorides is investigated. The study particularly emphasizes the influence of electrolyte additives—boric acid, chloride ions, and Na₂EDTA—on the electrochemical [...] Read more.

In the present study, the electrodeposition of thin Ni–Fe films obtained from aqueous electrolytes containing nickel (II) and iron (II) sulfates and chlorides is investigated. The study particularly emphasizes the influence of electrolyte additives—boric acid, chloride ions, and Na₂EDTA—on the electrochemical behavior, microstructure, and magnetic properties of the deposited layers. Cyclic voltammetry revealed a partial alignment of the reduction potentials of nickel and iron and the suppression of the hydrogen evolution side reaction up to −1 V. Electrodeposition in galvanostatic mode in the range of 0.5 to 1.0 A/dm² allows the formation of layers with iron contents between 20.5 wt. % to 41.4 wt. % and coating thickness from 1.3 to 3.0 µm. SEM and AFM observations demonstrated a pronounced dependence of the surface morphology on the current density, with higher current densities promoting the formation of dendritic structures. X-ray diffraction confirmed the dominance of a face-centered cubic (FCC) Ni-based solid solution, accompanied by minor contributions from non-stoichiometric Fe_1−xO. All the obtained Fe-Ni films have soft magnetic properties. Increasing the current density and the boric acid concentration causes the coercive force and isotropy of the layers to improve. The results demonstrate that thin Ni-Fe films with controlled structure and morphology, with favorable soft ferromagnetic properties suitable for functional applications, could be electrodeposited from complex chloride–sulfate electrolytes by adjusting the current density. Full article

(This article belongs to the Special Issue Advanced Coatings in Additive Manufacturing)

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24 pages, 6501 KB

Open AccessArticle

Preparation and Mechanism Study of Plasma-Sprayed Metal–Ceramic Composite Coatings Based on Microstructure

by Tianle Zhao and Jiantao Yao

Coatings 2026, 16(3), 364; https://doi.org/10.3390/coatings16030364 - 13 Mar 2026

Viewed by 398

Abstract

To overcome the limitations of single-phase plasma-sprayed coatings, where ceramic coatings exhibit high hardness but poor toughness while metallic coatings possess good ductility but insufficient hardness, AT40/Al metal–ceramic composite coatings were prepared by atmospheric plasma spraying. In this study, Al₂O₃ [...] Read more.

To overcome the limitations of single-phase plasma-sprayed coatings, where ceramic coatings exhibit high hardness but poor toughness while metallic coatings possess good ductility but insufficient hardness, AT40/Al metal–ceramic composite coatings were prepared by atmospheric plasma spraying. In this study, Al₂O₃–40%TiO₂ (AT40) ceramic was used as the hard phase and aluminum as the ductile phase. The effects of Al content (10%, 20%, and 30%) and key spraying parameters, including arc power (36–40 kW), spraying distance (85–130 mm), and gun traverse speed (400–1200 mm s⁻¹), on the microstructure and mechanical properties of the coatings were systematically investigated. The coatings were characterized using SEM, XRD, and EDS, and grey relational analysis was employed to evaluate the influence of process parameters. The results show that the introduction of an appropriate amount of Al significantly improves coating densification. When the Al content is 10%, the coating porosity decreases to 3.2%, compared with 8.5% for the pure AT40 coating. The optimal spraying parameters were determined to be 38 kW arc power, 100 mm spraying distance, and 400 mm s⁻¹ traverse speed, under which the coating exhibits a microhardness of 519.68 HV and a 45.3% improvement in impact resistance compared with the pure AT40 coating. Phase analysis indicates that partial transformation of α-Al₂O₃ to γ-Al₂O₃ occurs during spraying, while interfacial reactions between Al and TiO₂ lead to the formation of Al₂TiO₅, enhancing the interfacial bonding strength. The improved performance of the composite coating is attributed to the combined effects of structural densification, interfacial strengthening, and the synergistic interaction between ceramic and metallic phases. Full article

(This article belongs to the Section Ceramic Coatings and Engineering Technology)

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Coatings, Volume 16, Issue 3 (March 2026) – 124 articles

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