Coatings

31 pages, 4697 KB

Open AccessReview

Environmental Aging Mechanisms and Their Impact on the Mechanical Performance of Fiber-Reinforced Polymer Composites: A Comprehensive Review

by Tengwen Feng, Run Wang, Bing Du, Hanlin Ran, Yun Bai, Jingwei Liu and Feifei Fang

Coatings 2026, 16(6), 742; https://doi.org/10.3390/coatings16060742 (registering DOI) - 22 Jun 2026

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Abstract

Fiber-reinforced polymer (FRP) composites are extensively used in aerospace, civil engineering, and defense applications because of their low density, high specific strength, corrosion resistance, and structural design flexibility. However, prolonged exposure to hygrothermal conditions, ultraviolet (UV) radiation, and thermo-oxidative environments can progressively damage [...] Read more.

Fiber-reinforced polymer (FRP) composites are extensively used in aerospace, civil engineering, and defense applications because of their low density, high specific strength, corrosion resistance, and structural design flexibility. However, prolonged exposure to hygrothermal conditions, ultraviolet (UV) radiation, and thermo-oxidative environments can progressively damage these materials, leading to mechanical degradation and shortened service life. This review examines environmental aging in FRP composites at the levels of the polymer matrix, fiber/matrix interface, and reinforcing fibers. Representative predictive models, finite element methods, and experimental characterization techniques are summarized, together with the evolution of mechanical properties under different aging conditions. Hygrothermal degradation is mainly associated with moisture diffusion, matrix swelling, and interfacial debonding, whereas UV and thermo-oxidative aging are largely governed by photo-oxidation and thermally activated free-radical reactions. These processes may induce chain scission, crosslinking, matrix embrittlement, and interface damage. Under coupled environmental exposure, degradation is not simply additive because moisture transport, oxidation kinetics, and failure pathways may interact. Future research should emphasize multiscale characterization, anti-aging modification, interface engineering, protective coatings, and reliability-oriented lifetime prediction. Full article

(This article belongs to the Special Issue Mechanical, Wear, and Functional Properties of Composite Coatings)

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23 pages, 21830 KB

Open AccessArticle

Coupling Interaction of Swirl and Diameter on Particle Deposition and Degradation of Aerodynamic Performance for a Turbine Vane

by Jiajun He, Changce Wang, Li Shi, Rongli Deng, Xiao Tan, Haoyu Zhang, Yue Luo and Jiasheng Song

Coatings 2026, 16(6), 741; https://doi.org/10.3390/coatings16060741 (registering DOI) - 22 Jun 2026

Viewed by 197

Abstract

This study numerically investigates the effects of inlet swirl intensity on particle deposition on the surface of a static vane by adjusting the inlet swirl intensity and inlet hot streak conditions. The results indicate that swirl significantly alters the vane surface temperature distribution, [...] Read more.

This study numerically investigates the effects of inlet swirl intensity on particle deposition on the surface of a static vane by adjusting the inlet swirl intensity and inlet hot streak conditions. The results indicate that swirl significantly alters the vane surface temperature distribution, increasing the average surface temperature by up to 1.02% under the strongest swirl condition compared to the non-swirl case. On the pressure side, enhanced swirl shifts the high-temperature region toward the vane root, while on the suction side, the overall temperature increases. Particle deposition behavior is strongly size-dependent: swirl reduces the deposition efficiency for small particles but slightly increases it for large particles. Additionally, swirl modifies the deposition pattern, leading to the formation of dart-shaped grooves in the central pressure side and crescent-shaped protrusions near the trailing edge, which in turn affects the aerodynamic performance. The pressure-coefficient fluctuation is predominantly observed on the pressure side. These findings provide insight into the coupled effects of swirl and particle dynamics on vane surface degradation and flow behavior. Full article

(This article belongs to the Special Issue CMAS Penetration, Thermal Insulation Degradation, and Life Prediction of Thermal Barrier Coatings)

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12 pages, 4256 KB

Open AccessFeature PaperArticle

Waterborne Polyurethane-Based Sizing of Carbon Fibers for Improved Interfacial Performance of 3D-Printed Continuous Carbon Fiber/Polylactic Acid Composites

by Weidong Feng, Ling Ding, Wei Ruan, Zhenzhen Quan and Jianyong Yu

Coatings 2026, 16(6), 740; https://doi.org/10.3390/coatings16060740 (registering DOI) - 22 Jun 2026

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Abstract

3D-printed continuous carbon fiber-reinforced polylactic acid (CF/PLA) composites combine the high load-bearing capability of continuous fibers with the structural design freedom of additive manufacturing, showing broad application prospects in lightweight complex structures. However, the chemically inert surface of carbon fibers and their insufficient [...] Read more.

3D-printed continuous carbon fiber-reinforced polylactic acid (CF/PLA) composites combine the high load-bearing capability of continuous fibers with the structural design freedom of additive manufacturing, showing broad application prospects in lightweight complex structures. However, the chemically inert surface of carbon fibers and their insufficient interfacial compatibility with the PLA matrix lead to inefficient interfacial load transfer, thereby limiting the mechanical performance of the composites. In this study, a waterborne polyurethane (WPU)-based sizing treatment was applied to carbon fibers to enhance the fiber–matrix interface of 3D-printed continuous CF/PLA composites. The WPU sizing layer increased fiber-bundle cohesion and introduced a transition region between CF and PLA through possible hydrogen bonding, dipolar interactions, and physical adhesion. When the nominal WPU concentration was 5 wt%, the apparent interfacial shear strength reached 1.31 MPa, representing an improvement of approximately 65% compared with ACF/PLA. The three-point flexural strength reached 69.76 MPa, which was 55.3% higher than that of the ACF/PLA composite. These results indicate that WPU sizing is an effective and scalable interfacial regulation strategy for improving the mechanical properties of 3D-printed continuous CF/PLA composites. Full article

(This article belongs to the Special Issue Novel Materials and Coatings for Functional, Protective, and Sustainable Textiles and Wearables)

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19 pages, 28769 KB

Open AccessArticle

Differences in Microstructure and Properties of 16 mm Thick 6082 Aluminum Alloy Under Different Heat Source Conditions

by Zan Ju, Ruxu Huang, Xiaozhong Xie, Shu Liu, Feiyun Wang and Juan Fu

Coatings 2026, 16(6), 739; https://doi.org/10.3390/coatings16060739 (registering DOI) - 21 Jun 2026

Viewed by 241

Abstract

6082 aluminum alloy is widely applied in marine engineering, rail transportation and other industries owing to its excellent comprehensive performance. Welding heat source characteristics exert a decisive influence on the microstructure and mechanical properties of welded joints and become a major constraint for [...] Read more.

6082 aluminum alloy is widely applied in marine engineering, rail transportation and other industries owing to its excellent comprehensive performance. Welding heat source characteristics exert a decisive influence on the microstructure and mechanical properties of welded joints and become a major constraint for the application of medium-thick aluminum alloy welded structures. In this work, comparative tests of TIG and MIG welding were carried out on 16 mm thick 6082 aluminum alloy plates. Combining thermal simulation, metallographic observation and mechanical property tests, the temperature field distribution, microstructure, microhardness, tensile properties and bending properties of the two kinds of joints were systematically studied. The results show that TIG welding possesses high heat input, forming a broad temperature field with steep thermal gradients. Its weld microstructure is coarse and accompanied by severe coarsening of Mg₂Si precipitates, and the joint presents a highly fluctuating M-shaped microhardness distribution. The average tensile strength of TIG welded joints is 194 MPa, and all specimens fracture in the heat-affected zone. By contrast, MIG welding with low heat input produces a uniform temperature field, as well as a fine and homogeneous weld microstructure with dispersed precipitates. Its microhardness distribution is stable, and the average tensile strength reaches 256 MPa, 32% higher than that of TIG joints. Both welding methods deliver favorable bending performance. The difference in heat input and cooling behavior changes the grain evolution and precipitate characteristics and further dominates the final mechanical performance of joints. MIG welding is more suitable for multi-layer, multi-pass welding of 16 mm thick 6082 aluminum alloy. This work clarifies the correlation between heat input, microstructure and mechanical properties, and the optimized process can effectively improve the microstructural uniformity of the weld joint and enhance its mechanical properties. Full article

(This article belongs to the Special Issue Laser-Based Additive Manufacturing and Surface Engineering for Advanced Coatings)

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13 pages, 1149 KB

Open AccessFeature PaperArticle

Material Microstructure and Mechanical Properties of Spark Plasma-Sintered Al_0.2CoCrFeNi-5%WC High-Entropy Alloy Composites: A Sintering Temperature Study

by Hui Liang, Ziwen Hong, Qian Liu, Jingzhuo Zhang, Jinxin Hou, Dongxu Qiao, Yangming Liu, Hanshu Zhao, Yingfan Zhai, Kaiyue Yang, Li Jiang, Jinhu Yu and Zhiqiang Cao

Coatings 2026, 16(6), 738; https://doi.org/10.3390/coatings16060738 (registering DOI) - 21 Jun 2026

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Abstract

Al_0.2CoCrFeNi-5%WC high-entropy alloy (HEA) composites were fabricated via spark plasma sintering at temperatures ranging from 900 °C to 1050 °C, and the effects of sintering temperature on phase constitution, microstructure, and mechanical properties were systematically investigated. The results show that all [...] Read more.

Al_0.2CoCrFeNi-5%WC high-entropy alloy (HEA) composites were fabricated via spark plasma sintering at temperatures ranging from 900 °C to 1050 °C, and the effects of sintering temperature on phase constitution, microstructure, and mechanical properties were systematically investigated. The results show that all composites consist predominantly of an FCC matrix, WC, M₂₃C₆ and M₆C carbides. With increasing sintering temperature, interfacial reactions are promoted, leading to the progressive consumption of WC and an increase in carbide content. The composite sintered at 1000 °C achieves the optimal combination of properties, with a relative density of 96.8%, a yield strength of 468 MPa, an ultimate compressive strength of 1871 MPa, and a fracture strain of 43.6%. The outstanding strength–ductility synergy originates from near-full densification, robust interfacial bonding, and multiple carbide strengthening mechanisms. Excessively high sintering temperature (1050 °C) results in reinforcement coarsening and degradation of mechanical properties. Full article

(This article belongs to the Section Composite Coatings)

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17 pages, 4371 KB

Open AccessFeature PaperArticle

Preparation of High-Quality Low-Temperature PECVD Silicon Nitride Films: Effect of NH₃ Precursor on Film Properties and RF Response Mechanism

by Zhen Tang, Peng Yu, Yanli Qi, Zhuo Wang, Jianping Ning and Zhaohui Ren

Coatings 2026, 16(6), 737; https://doi.org/10.3390/coatings16060737 (registering DOI) - 21 Jun 2026

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Abstract

With the shift in advanced packaging toward 3D integration and flexible electronics, it is becoming critical to produce high-quality silicon nitride films under low thermal budgets. To overcome the limitations of low-temperature deposition, this study compares two gas mixtures—SiH₄/NH₃/N [...] Read more.

With the shift in advanced packaging toward 3D integration and flexible electronics, it is becoming critical to produce high-quality silicon nitride films under low thermal budgets. To overcome the limitations of low-temperature deposition, this study compares two gas mixtures—SiH₄/NH₃/N₂ and SiH₄/N₂—in plasma-enhanced chemical vapor deposition of silicon nitride coatings. We systematically evaluated how the NH₃ precursor affects deposition kinetics, chemical bonds, non-uniformity, optical properties, and internal stress at different RF powers and electrode gaps. The test results show that NH₃, with its lower dissociation energy, avoids the high activation barrier associated with pure N₂ plasma, leading to a higher reactive nitrogen flux and a doubled deposition rate. In the SiH₄/NH₃/N₂ system, raising RF power from 300 W to 900 W reduced hydrogen content from 23.58% to 12.25%. This suppression of hydrogen promoted structural densification, shifting the mechanical stress from 173.3 MPa to −989.7 MPa. At a larger electrode gap of 19 mm, NH₃’s better diffusion characteristics offset the electric field sensitivity typical of N₂ systems, reducing large-area film non-uniformity by 28.7% compared to a 13 mm gap. This work offers a practical, mass-production-friendly approach for depositing robust, low-hydrogen, highly uniform silicon nitride films at low temperatures. Full article

(This article belongs to the Special Issue 2D Materials-Based Thin Films and Coatings, 2nd Edition)

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56 pages, 8337 KB

Open AccessReview

Electrospun Nanofibers for Antimicrobial Therapy: From Polymer Design to Controlled Drug Release

by Andrei Teodor Matei, Oana Cramariuc, Irina Negut and Iuliana Gabriela Lupu

Coatings 2026, 16(6), 736; https://doi.org/10.3390/coatings16060736 (registering DOI) - 20 Jun 2026

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Abstract

The rapid emergence of antimicrobial resistance has intensified the need for advanced therapeutic platforms capable of improving the efficacy, stability, and targeted delivery of antimicrobial agents. Electrospun nanofibers have emerged as highly promising materials for biomedical applications due to their large surface area, [...] Read more.

The rapid emergence of antimicrobial resistance has intensified the need for advanced therapeutic platforms capable of improving the efficacy, stability, and targeted delivery of antimicrobial agents. Electrospun nanofibers have emerged as highly promising materials for biomedical applications due to their large surface area, high porosity, tunable morphology, and ability to incorporate a broad range of bioactive compounds. This review provides a comprehensive overview of the design, fabrication, and biomedical applications of electrospun bioactive nanofibers functionalized with antimicrobial drugs. It presents the main nanofiber fabrication techniques, with particular emphasis on electrospinning and the influence of solution, process, and environmental parameters on fiber morphology and drug-loading efficiency. Natural, synthetic, and hybrid polymer systems commonly employed in electrospun antimicrobial nanofibers are analyzed in relation to their physicochemical properties, biocompatibility, and therapeutic performance. In addition, the review highlights different drug incorporation strategies, including encapsulation, immobilization, and surface coating, as well as the mechanisms of action of antimicrobial agents. Recent advances in nanotechnology-based antimicrobial systems and their role in overcoming analytical, biopharmaceutical, and drug-delivery limitations are also examined. Furthermore, the review addresses current challenges related to scalability, reproducibility, stability, and clinical translation of electrospun nanofibers. Finally, future perspectives focusing on multifunctional, stimuli-responsive, and personalized antimicrobial nanofiber systems are discussed as promising directions for combating bacterial infections and reducing the global burden of antimicrobial resistance. Full article

(This article belongs to the Special Issue Advanced Surface Modifications for Biomedical Applications: Enhancing Biocompatibility and Bioactivity)

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Graphical abstract

15 pages, 26045 KB

Open AccessArticle

Crystal Plasticity Finite Element Simulation and Quasi-In-Situ Experimental Study of Tensile Strain Partitioning in Multiphase High-Strength Steel

by Qilong Jia, Bingyi Wang, Yafei Xue, Lin Zhang, Yi Sun, Sujuan Yuan, Dongyun Sun, Peng Zhang, Xiaowen Sun, Xiaoyong Feng and Fucheng Zhang

Coatings 2026, 16(6), 735; https://doi.org/10.3390/coatings16060735 (registering DOI) - 20 Jun 2026

Viewed by 239

Abstract

A multiphase high-strength steel austempered at 260 °C for 24 h was investigated by quasi-in-situ tensile characterization and EBSD-based crystal plasticity finite element modeling. The experimental observations reveal that local plastic deformation is strongly heterogeneous: von Mises strain concentrates preferentially near bainitic-ferrite packets, [...] Read more.

A multiphase high-strength steel austempered at 260 °C for 24 h was investigated by quasi-in-situ tensile characterization and EBSD-based crystal plasticity finite element modeling. The experimental observations reveal that local plastic deformation is strongly heterogeneous: von Mises strain concentrates preferentially near bainitic-ferrite packets, phase boundaries, and retained-austenite/martensite–austenite regions, whereas blocky retained austenite contributes to strain accommodation at the early deformation stage. To quantify the underlying stress–strain partitioning, a quasi-two-dimensional representative volume element was reconstructed from EBSD data and implemented in ABAQUS through a user-defined material subroutine. The model contained the real grain morphology, phase distribution, and crystal orientation information of the 24 h austempered specimen. A rate-dependent crystal plasticity constitutive framework with BCC matrix, FCC retained austenite, and transformed martensite branches was calibrated against the macroscopic tensile curve. The simulated tensile response agrees well with the experimental curve before macroscopic instability, and the predicted local fields are consistent with the quasi-in-situ strain maps. The results show that local plastic strain first accumulates in M/A-related regions and phase-boundary-neighboring zones, while high Mises stress migrates dynamically with slip activity and stress-induced martensitic transformation. Retained-austenite transformation increases the local load-bearing capacity, modifies interphase load transfer, and delays the direct linkage of strain-localization bands. The present work clarifies the coupling among retained-austenite stability, TRIP-assisted load redistribution, and microstructural strain partitioning in multiphase high-strength steel, providing a mesoscale basis for microstructure-guided strength–ductility optimization. Full article

(This article belongs to the Section Surface Characterization, Deposition and Modification)

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16 pages, 32529 KB

Open AccessArticle

Quantitative Analysis of the Effect of Rolling Process on the Mechanical Properties of Mg-Sm Alloy

by Jianchao Chen, Bo Guan, Wenzheng Liu, Jiahao Wang, Jing Xu, Hong Yan, Qiang Hu and Yunchang Xin

Coatings 2026, 16(6), 734; https://doi.org/10.3390/coatings16060734 (registering DOI) - 19 Jun 2026

Viewed by 222

Abstract

Magnesium (Mg) alloy sheets usually suffer from severe mechanical anisotropy and a trade-off between strength and ductility. In this work, the effects of rolling temperature (200 °C and 400 °C) and rolling speed (50–1000 r/min) on the microstructure and mechanical properties of a [...] Read more.

Magnesium (Mg) alloy sheets usually suffer from severe mechanical anisotropy and a trade-off between strength and ductility. In this work, the effects of rolling temperature (200 °C and 400 °C) and rolling speed (50–1000 r/min) on the microstructure and mechanical properties of a Mg-1Sm (samarium, Sm) (wt.%) alloy were systematically investigated. Low-temperature rolling (200 °C) results in high dislocation density and a double-peak basal texture in Mg-1Sm alloy, causing very limited plasticity and a pronounced anisotropy with a lower yield strength along the rolling direction (RD) than along the transverse direction (TD). A significantly improved mechanical property (yield strength of ~196 MPa, elongation of 18.4% and near-isotropy) can be achieved in the Mg-1Sm alloy by optimizing the rolling conditions (400 °C, 500 r/min). The findings indicate that increasing the temperature is beneficial for activating non-basal slip and multiple twinning modes, thereby weakening and dispersing the basal texture, which can efficiently improve the anisotropic properties. Increasing the rolling speed can promote the recrystallization process, resulting in the enhancement of plasticity. Quantitative analyses reveal that the reduction in dislocation density and the suppression of Sm segregation at grain boundaries under high-temperature high-speed rolling are responsible for the improved ductility and reduced anisotropy. Full article

(This article belongs to the Section Metal Surface Process)

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16 pages, 38069 KB

Open AccessArticle

Fabrication, Microstructural and Micro-Mechanical Characterization of Ti-Nb-HA Composite Under Micro-Pillar Compression

by Abdulaziz Kurdi, Doaa Almalki, Husain Alnaser, Ahmed Degnah and Animesh Kumar Basak

Coatings 2026, 16(6), 733; https://doi.org/10.3390/coatings16060733 (registering DOI) - 19 Jun 2026

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Abstract

The present work reports on the microstructural and micro-mechanical characterization of Ti-Nb-HA-based composites. The composites were prepared via a spark plasma sintering (SPS) consolidation process. The effect of two distinct levels of hydroxyapatite (HA) content (e.g., 10 and 20 wt.%) on the microstructural [...] Read more.

The present work reports on the microstructural and micro-mechanical characterization of Ti-Nb-HA-based composites. The composites were prepared via a spark plasma sintering (SPS) consolidation process. The effect of two distinct levels of hydroxyapatite (HA) content (e.g., 10 and 20 wt.%) on the microstructural and micro-mechanical properties were investigated via in situ micro-pillar compression, and the results were compared against a sole Ti-Nb composite. The microstructure of the composites was composed of parent Ti and Nb grains, together with the reaction products; due to the decomposition of HA, there was a rise in different biocompatible phases. The Vickers hardness of the composite was sensitive to applied loads due to the presence of pores and voids, which was foreseen to be beneficial when the composite was used as an implant, according to the literature. The addition of 20 wt.% HA causes a decrease in hardness to 990 HV, compared to 1109 HV for 10 wt.% HA and 1275 HV for sole Ti-Nb. The addition of HA into Ti-Nb also lowers the compressive strength from 553 MPa for Ti-Nb to 189 MPa for Ti-30Nb-20HA. This was accompanied by a reduction in the elastic modulus, from 130 GPa for Ti-Nb to 29 GPa for Ti-30Nb-20HA. The deformation mechanism was ductile-dominated in all cases, with the presence of a quasi-brittle nature for HA-containing composites. Full article

(This article belongs to the Section Metal Surface Process)

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19 pages, 5438 KB

Open AccessArticle

Influence of Titanium Concentration on Piezoresistive Characteristics of DLC:Ti Films

by Weihao Lun, Shihao Shi, Zhengtao Wu, Haiqing Li, Qimin Wang and Yisong Lin

Coatings 2026, 16(6), 732; https://doi.org/10.3390/coatings16060732 (registering DOI) - 19 Jun 2026

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Abstract

Titanium-doped diamond-like carbon (DLC:Ti) films were deposited by magnetron sputtering. The effects of Ti concentration on the microstructure, phase composition and piezoresistive properties of the films were systematically investigated. The surface morphology, crystal structure and chemical bonding states of the samples were characterized [...] Read more.

Titanium-doped diamond-like carbon (DLC:Ti) films were deposited by magnetron sputtering. The effects of Ti concentration on the microstructure, phase composition and piezoresistive properties of the films were systematically investigated. The surface morphology, crystal structure and chemical bonding states of the samples were characterized using SEM, XRD and XPS. The piezoresistive properties were then assessed by monitoring the resistance change in the thin films using a precision resistance meter under controlled external stimulation. The results demonstrate that the sp²/sp³ ratio of the DLC:Ti films increases with rising Ti concentration, and both Ti–C and Ti–Ti chemical bonds are formed within the films. An excessive β-Ti phase forms when the Ti concentration exceeds 39.7 at.%. The electrical resistance of DLC:Ti films decreases linearly as the applied normal stress increases from 0 to 35 MPa, with a maximum piezoresistive coefficient of −9.0 × 10⁻² GPa⁻¹ achieved for the film with a Ti doping concentration of 12.9 at.%. One hundred cyclic loading–unloading tests induce the structural transition from sp³ to sp², resulting in the graphitization of DLC:Ti films. In addition, external stress facilitates the fracture of Ti–C bonds and the relaxation of residual stress in the DLC:Ti films; the β- to α-Ti phase transformation induced by external loading is also observed in the films. Cyclic piezoresistive tests reveal that the piezoresistive stability of the DLC:Ti films is enhanced with increasing Ti concentration, which is attributed to the increased formation of Ti–C bonds in the films. Full article

(This article belongs to the Topic Advances in Coatings Technology and Their Multidisciplinary Applications)

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14 pages, 6695 KB

Open AccessArticle

Anisotropic Mechanical Behavior and Localized Deformation Evolution in Q420 High-Strength Steel

by Nan Guo, Yangyang Li, Yaoyao Li, Xiqiang Ma, Xiao Wang and Chunyang Liu

Coatings 2026, 16(6), 731; https://doi.org/10.3390/coatings16060731 (registering DOI) - 18 Jun 2026

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Abstract

Q420 high-strength steel exhibits pronounced anisotropy due to its rolling process, and conventional uniaxial tensile testing is incapable of acquiring strain field evolution information during the local necking stage. In this study, quasi-static uniaxial tensile tests were conducted on Q420 cold-rolled high-strength steel [...] Read more.

Q420 high-strength steel exhibits pronounced anisotropy due to its rolling process, and conventional uniaxial tensile testing is incapable of acquiring strain field evolution information during the local necking stage. In this study, quasi-static uniaxial tensile tests were conducted on Q420 cold-rolled high-strength steel sheets at six orientations (0°, 15°, 30°, 45°, 60°, and 90°) using Digital Image Correlation (DIC) technology. The evolution of the strain field and the corresponding stress–strain responses at different orientations were systematically investigated. The results show that the DIC technique effectively captured the full-field strain evolution of the specimens from uniform deformation to local necking and final fracture in all directions. Taking the 0° direction as an example, the local maximum engineering strain prior to fracture reached 35.866%, whereas the average fracture strain within the gauge section was only approximately 22.5%, corresponding to a ratio of approximately 1.6 and clearly demonstrating the severe strain concentration within the necking zone. The stress–strain curves corresponding to different rolling directions exhibited pronounced anisotropy. The tensile strength was highest in the 90° direction and lowest in the 0° direction; however, the 0° direction exhibited the best ductility, whereas the 45° direction showed the poorest ductility. Among the six orientations, the midpoint transverse engineering strain exhibited the largest absolute value in the 45° direction, further indicating that this orientation is the most susceptible to plastic instability. In this work, DIC-based full-field measurement was combined with multi-directional tensile testing to quantitatively characterize the relationship between local strain concentration and anisotropy. The findings provide high-precision experimental data for the calibration of anisotropic constitutive models and the optimization of forming processes. Full article

(This article belongs to the Special Issue Laser Welding and Cladding for Enhanced Mechanical Performance)

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24 pages, 26267 KB

Open AccessArticle

Seismic Fragility Assessment of Reinforced Concrete Bridge Under Near-Fault Pulse-like Ground Motions Considering Structural Parameter Uncertainties

by Zekai Ma, Chao Yin, Jiagu Chen and Jiaxu Li

Coatings 2026, 16(6), 730; https://doi.org/10.3390/coatings16060730 (registering DOI) - 18 Jun 2026

Viewed by 188

Abstract

Near-fault pulse-like ground motions (NFPLGMs) impose concentrated energy demands that can severely damage bridges, yet their scarcity and the influence of structural parameter uncertainties are often neglected in seismic fragility assessments. This study proposed a synthesis method for NFPLGMs by superposing low-frequency pulse [...] Read more.

Near-fault pulse-like ground motions (NFPLGMs) impose concentrated energy demands that can severely damage bridges, yet their scarcity and the influence of structural parameter uncertainties are often neglected in seismic fragility assessments. This study proposed a synthesis method for NFPLGMs by superposing low-frequency pulse components (extracted via the Gabor wavelet transform and low-pass filtering) with high-frequency stochastic components based on an evolutionary power spectrum. A three-span reinforced concrete bridge was modeled in OpenSeesPy, and Incremental Dynamic Analysis (IDA), together with a quadratic response surface model, were used to plot seismic fragility curves. The damping ratio (ξ), elastic modulus of steel reinforcement (E_s), yield strength of steel reinforcement (f_y), diameter of longitudinal reinforcement (D), and peak ground acceleration (PGA) were treated as random variables. Sensitivity indices were computed using Monte Carlo sampling (n = 10,000). Results show that ξ most strongly affects the displacement ductility ratio of the bridge pier (u_d) (variation of up to 32.6%), while E_s dominates the shear deformation of the bridge bearing (d) (variation of up to 43.8%). Neglecting structural parameter uncertainties overestimates median PGA thresholds (m_R) for different damage states by 1.5%–36.1%, and replacing NFPLGMs with ordinary ground motions overestimates seismic capacity by 1.7%–36.6%. The bridge bearing is consistently more vulnerable than the pier, with a collapse probability of 0.9566 at PGA = 1.0 g. These findings highlight the necessity of incorporating both NFPLGM characteristics and structural parameter uncertainties into bridge seismic fragility assessment. On the other hand, when seismic retrofitting of bridges is carried out using coating materials, priority should be given to more vulnerable components, such as bridge bearings, to improve the utilization efficiency of limited resources. Full article

(This article belongs to the Special Issue Surface Treatments and Coatings for Asphalt and Concrete)

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12 pages, 12569 KB

Open AccessArticle

Microstructural Evolution and Thermal Transport in APS SrZrO₃ Coatings: An EBSD-Focused Study

by Matiullah Khan and Yi Zeng

Coatings 2026, 16(6), 729; https://doi.org/10.3390/coatings16060729 (registering DOI) - 18 Jun 2026

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Abstract

This work reports the combination of pentagonal grain morphology, high phase purity, and non-monotonic thermal conductivity behavior over a wide temperature range (25–1200 °C). The SrZrO₃ coatings with different processing parameters are deposited using atmospheric plasma spraying (APS). Unlike conventional atmospheric plasma-sprayed [...] Read more.

This work reports the combination of pentagonal grain morphology, high phase purity, and non-monotonic thermal conductivity behavior over a wide temperature range (25–1200 °C). The SrZrO₃ coatings with different processing parameters are deposited using atmospheric plasma spraying (APS). Unlike conventional atmospheric plasma-sprayed oxide coatings, distinct pentagonal-shaped grains with multi-directional orientation suggest a unique solidification pathway and anisotropic growth mechanism. The pentagonal morphology may come from the impingement of five radially columnar grain sectors during rapid solidification of a highly undercooled melt splat, constrained by local thermal gradients. This atypical morphology, not commonly reported for SrZrO₃ coatings, is further supported by electron backscatter diffraction (EBSD) results, which confirm a remarkably high phase fraction (~94.5%) of SrZrO₃ despite rapid quenching inherent to APS processing. The combination of high phase purity and unusual grain geometry represents a significant advancement in tailoring the microstructures of environmental barrier materials. Moreover, the non-linear thermal conductivity response with temperature shows a pronounced decrease up to ~800 °C (0.737 W·m⁻¹·K⁻¹) stabilization between 800 and 900 °C, and a subsequent increase at higher temperatures. This behavior indicates a complex interplay between phonon scattering, defect structures, and possible radiative heat transfer contributions at elevated temperatures. Full article

(This article belongs to the Special Issue Performance and Applications of Environmental Barrier Coatings (EBCs)/Thermal Barrier Coatings (TBCs))

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19 pages, 11931 KB

Open AccessArticle

Crack Suppression and Performance Analysis of Novel Ni60 Alloy Hardbanding on Drillpipes via Laser Cladding

by Lilan Liu, Shen Wang, Yingkai Qin, Boyu Guo, Ziying Wu and Feiyan Han

Coatings 2026, 16(6), 728; https://doi.org/10.3390/coatings16060728 (registering DOI) - 18 Jun 2026

Viewed by 257

Abstract

With the continuous advancement of drilling technologies for deep and ultra-deep well operations, drillpipes are subjected to increasingly severe wear and corrosion conditions. To enhance the wear and corrosion resistance of drillpipe surfaces, this study developed a novel Ni60 alloy hardbanding via laser [...] Read more.

With the continuous advancement of drilling technologies for deep and ultra-deep well operations, drillpipes are subjected to increasingly severe wear and corrosion conditions. To enhance the wear and corrosion resistance of drillpipe surfaces, this study developed a novel Ni60 alloy hardbanding via laser cladding technology. To solve the problem of crack sensitivity, the cracking mechanism of Ni60 coatings directly deposited on 4137H steel substrates was systematically investigated and a crack suppression strategy was proposed. By employing a 316L translation layer between the 4137H substrate and the Ni60 alloy coating, the interfacial thermal stress induced by the mismatch of thermal expansion coefficients between dissimilar materials was relieved. Therefore, crack-free 316L-Ni60 gradient coatings were obtained. The microstructure, phase composition, and mechanical properties of the coatings were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and microhardness testing. The experimental results demonstrate that the 316L-Ni60 gradient coating exhibits a homogeneous microstructure and forms a dense metallurgical bond with the 4137H steel. The microhardness of the coating is 2.2 times that of the 4137H steel, while its wear rate is reduced by nearly half. Furthermore, the Ni60 coating possesses higher corrosion resistance compared with 4137H steel. This study promotes the potential application of the Ni60 alloy coating as a new type of hardbanding on drillpipes. Full article

(This article belongs to the Section Surface Characterization, Deposition and Modification)

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17 pages, 3501 KB

Open AccessArticle

Microstructure and Mechanical Properties of YSZ Coating in TBCs on Rotating Curved Substrates Deposited at Different Standoff Distances

by Pan Li, Hui Dong, Yukun Feng, Yong Zhou and Lishuang Wang

Coatings 2026, 16(6), 727; https://doi.org/10.3390/coatings16060727 - 18 Jun 2026

Viewed by 254

Abstract

To address the issue of depositing thermal barrier coatings (TBCs) on rotating curved surfaces, atmospheric plasma spraying (APS) was employed to prepare yttria partially stabilized zirconia (YSZ) coatings on a rotating curved substrate. Three standoff distances of 80 mm, 100 mm and 120 [...] Read more.

To address the issue of depositing thermal barrier coatings (TBCs) on rotating curved surfaces, atmospheric plasma spraying (APS) was employed to prepare yttria partially stabilized zirconia (YSZ) coatings on a rotating curved substrate. Three standoff distances of 80 mm, 100 mm and 120 mm were selected. The microstructure, microhardness, elastic modulus and fracture toughness of three YSZ coatings were tested. The results indicate that as the standoff distance increased from 80 mm to 120 mm, porosity increased from 11.27% to 13.29%, microhardness decreased from 760.8 HV_0.3 to 713.2 HV_0.3, elastic modulus decreased from 24.0 GPa to 22.6 GPa, and fracture toughness decreased from 1.14 MPa·m^1/2 to 1.04 MPa·m^1/2. The properties of the YSZ coating in the case, such as elastic modulus and fracture toughness, were significantly lower than those of the YSZ coating deposited on stationary planar substrates. Solidification of the molten particles impacted on rotating curved substrates was accelerated and splat spreading was constrained because of the coupled effect of centrifugal force and elevated cooling rate. Therefore, under identical spraying parameters, the process parameters optimized for planar substrates cannot be directly transferred to rotating curved components. Full article

(This article belongs to the Special Issue Novel Protective Coatings on Anti-Oxidation, Anti-Wear, and Corrosion Resistance Properties)

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17 pages, 3223 KB

Open AccessArticle

The Mechanical Strengths and Resistance to Chloride Salt Erosion of Iron Tailings Powder with Self-Compacting Concrete with Hybrid Fibers

by Ligai Bai, Chenxi Gao, Guihua Yang, Youheng Zhang, Huamin Cai, Feiting Shi and Wenxiu Guo

Coatings 2026, 16(6), 726; https://doi.org/10.3390/coatings16060726 - 18 Jun 2026

Viewed by 231

Abstract

In this study, the fluidity and the flexural and compressive strengths of self-compacting concrete with iron tailings powder are measured. The influence of basalt fibers and steel fibers on the mechanical strengths and the attenuation of performance after NaCl erosion has been investigated. [...] Read more.

In this study, the fluidity and the flexural and compressive strengths of self-compacting concrete with iron tailings powder are measured. The influence of basalt fibers and steel fibers on the mechanical strengths and the attenuation of performance after NaCl erosion has been investigated. The mass ratio of iron tailings powder ranges from 0% to 20%. The volume ratio of fibers increases from 0% to 3.5%. The influence of hybrid basalt-steel fibers is considered. The results indicate that the mechanical properties vary in the form of cubic functions with the mass ratio of iron tailings powder and the volume ratio of fibers. Specimens with 15% iron tailings powder exhibit the highest mechanical performance. At this dosage, the flexural and compressive strengths are increased by rates of 12.2% and 8.5%, respectively. Specimens reinforced with 2% basalt fibers or 2.5% steel fibers individually exhibit the highest mechanical performance, the lowest chloride ion impermeability, and the best resistance to chloride salt erosion. The hybrid combination of 0.5% basalt fibers and 3% steel fibers provides the optimal fiber dosage. An amount of 2% basalt fibers or 2% steel fibers increase the flexural strengths by rates of up to 48.9% and 84.8%, respectively, while the corresponding compressive strengths are increased by up to 12.5% and 20.9%. The chloride ion migration coefficient of specimens are decreased by up to 37.86%, 30%, and 42.14% with 2.5% basalt fibers, 2% steel fibers, and a hybrid combination of 1.5% basalt fibers and 1% steel fibers, respectively. Specimens with 15% iron tailings powder exhibit the highest amount of dense hydration products and the least amount of cracks. Full article

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

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22 pages, 17434 KB

Open AccessFeature PaperArticle

High-Performance Co–N- and Cu–N-Doped Activated Carbon Catalysts for Hydrazine Oxidation and Direct N₂H₄–H₂O₂ Fuel Cells

by Virginija Ulevičienė, Daina Upskuvienė, Aldona Balčiūnaitė, Aleksandrs Volperts, Ance Plavniece, Giedrius Stalnionis, Loreta Tamašauskaitė-Tamašiūnaitė and Eugenijus Norkus

Coatings 2026, 16(6), 725; https://doi.org/10.3390/coatings16060725 - 18 Jun 2026

Viewed by 373

Abstract

The development of sustainable electrocatalysts for clean energy by modifying biomass-derived activated carbon with nitrogen and transition metals is presented. Activated carbon (AWC) material was obtained using alder wood char as a precursor, while nitrogen and cobalt or copper nanoparticles were incorporated with [...] Read more.

The development of sustainable electrocatalysts for clean energy by modifying biomass-derived activated carbon with nitrogen and transition metals is presented. Activated carbon (AWC) material was obtained using alder wood char as a precursor, while nitrogen and cobalt or copper nanoparticles were incorporated with the aim of creating efficient materials for hydrazine oxidation (HzOR) and direct hydrazine–hydrogen peroxide fuel cells (DHHPFC, N₂H₄–H₂O₂). The composition, structure, and surface morphology of the created materials were examined using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), and inductively coupled plasma optical emission spectroscopy (ICP-OES). The activity of the AWC, AWC–Co–N, and AWC–Cu–N catalysts for HzOR was investigated using cyclic voltammetry (CV) and linear sweep voltammetry (LSV). N₂H₄–H₂O₂ fuel-cell tests were performed by applying the catalysts as both the anode and cathode. It was found that all materials retained a hierarchical porous carbon framework, while metal incorporation altered surface compactness. Cobalt doping produced well-dispersed Co nanoparticles and abundant Co–N–C coordination sites, whereas Cu introduction resulted in moderately compact structures with uniformly distributed Cu-based nanoparticles. Electrochemical measurements demonstrated that both metal dopants enhanced HzOR activity, with the catalytic performance following the order of AWC–Co–N > AWC–Cu–N > AWC. Fuel-cell testing further confirmed this trend: AWC–Co–N achieved the highest maximum power density (30.4 mW cm⁻²), outperforming AWC–Cu–N (17.7 mW cm⁻²). These results identify AWC–Co–N as a highly effective bifunctional electrocatalyst for DHHPFCs. Full article

(This article belongs to the Special Issue New Advances in Nanoparticles, Fiber, and Coatings—2nd Edition)

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18 pages, 20204 KB

Open AccessFeature PaperArticle

Adhesion of Trivalent Chromium Coatings on Steel: Assessment by Tensile Testing and AFM Surface Energy Measurements

by Robin Guillon, Yannick Balcaen, Olivier Dalverny and Joel Alexis

Coatings 2026, 16(6), 724; https://doi.org/10.3390/coatings16060724 - 17 Jun 2026

Viewed by 276

Abstract

Hard chromium coatings are widely used for their excellent wear and corrosion resistance, but replacing conventional hexavalent chromium with safer trivalent chromium processes remains limited by adhesion-related issues. This study proposes a simple, quantitative method for evaluating the adhesion of hard chromium coatings [...] Read more.

Hard chromium coatings are widely used for their excellent wear and corrosion resistance, but replacing conventional hexavalent chromium with safer trivalent chromium processes remains limited by adhesion-related issues. This study proposes a simple, quantitative method for evaluating the adhesion of hard chromium coatings deposited on ductile steel substrates using an instrumented uniaxial tensile test. Adhesion is defined as the substrate strain at the onset of coating cracking or delamination, while damage evolution is monitored in situ using optical imaging. Trivalent chromium coatings, produced using four different surface preparation routes, were investigated and compared with conventional hexavalent chromium coatings used as references. Fractographic SEM/EDS analyses were performed to identify cohesive and adhesive failure modes. In parallel, the substrate surface energy prior to coating deposition was assessed using atomic force microscopy via pull-off force measurements. The tensile test successfully differentiated the adhesion performance associated with the different surface preparations. A strong correlation was observed between the critical strain measured during tensile testing and the AFM-derived pull-off forces, highlighting the major influence of substrate pretreatment on coating adhesion. The proposed methodology provides a practical tool for the qualification and optimization of hard chromium coating processes. Full article

(This article belongs to the Section Surface Characterization, Deposition and Modification)

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14 pages, 2361 KB

Open AccessArticle

Investigation of a Highly Sensitive D-Type Photonic Crystal Fiber Utilizing Surface Plasmon Resonance

by Yuxin Zhan, Jiabin Li, Haifang Liu, Ruilin Cui, Juan Gao, Xuezhi Yang and Zao Yi

Coatings 2026, 16(6), 723; https://doi.org/10.3390/coatings16060723 - 17 Jun 2026

Viewed by 317

Abstract

Due to the limited application of sensors in the low-refractive-index range, accurate detection of certain low-refractive-index objects remains challenging. To address this limitation, this study proposes a novel D-shaped photonic crystal fiber (PCF) operating on the surface plasmon resonance (SPR) principle. Distinct from [...] Read more.

Due to the limited application of sensors in the low-refractive-index range, accurate detection of certain low-refractive-index objects remains challenging. To address this limitation, this study proposes a novel D-shaped photonic crystal fiber (PCF) operating on the surface plasmon resonance (SPR) principle. Distinct from conventional D-type PCF designs, the proposed structure employs an open-loop channel coated with a gold film to enable efficient excitation. Finite element analysis shows that the sensor’s detection range of refractive index is between 1.23 and 1.32. With increasing analyte refractive index, the loss peak exhibits progressive broadening and eventual stabilization. A maximum spectral sensitivity of 18,500 nm/RIU and a resolution of 5.41 × 10⁻⁶ RIU are attained at a refractive index of 1.32. The sensor features a straightforward design and exhibits excellent performance characteristics. Its exceptional sensing capabilities make it highly competitive for use in applications with a low refractive index. At the same time, to optimize the sensing performance, this study investigates how structural parameters affect the resonant spectrum. Full article

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

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25 pages, 21938 KB

Open AccessFeature PaperArticle

Surface Evolution of an FDM-Printed PLA Component with Multiple Geometries During Centrifugal Disc Finishing

by Jackson William Chadwick, Andrew Naylor, Tahsin Tecelli Öpöz, Juan Ignacio Ahuir-Torres and Xiaoxiao Liu

Coatings 2026, 16(6), 722; https://doi.org/10.3390/coatings16060722 - 17 Jun 2026

Viewed by 300

Abstract

Additive manufacturing (AM) enables the fabrication of complex, customisable components from metals, composites and polymers such as polylactic acid (PLA); however, the process commonly produces poor surface finishes and inherent defects. Centrifugal disc finishing (CDF) is an established mass finishing technique in conventional [...] Read more.

Additive manufacturing (AM) enables the fabrication of complex, customisable components from metals, composites and polymers such as polylactic acid (PLA); however, the process commonly produces poor surface finishes and inherent defects. Centrifugal disc finishing (CDF) is an established mass finishing technique in conventional manufacturing but remains insufficiently characterised for additively manufactured polymers. This exploratory study investigates the influence of CDF on fused deposition modelling (FDM)-fabricated PLA components with varying geometrical features, focusing on three-dimensional surface parameters including average areal surface roughness, skewness and kurtosis. Samples were processed up to 720 min with analysis at predetermined intervals to capture transient and steady-state-like behaviour. Surface characterisation was conducted using non-contact optical interferometry to obtain quantitative roughness data and three-dimensional topographical maps, supported by digital optical microscopy and gravimetric analysis to quantify material removal rates. Analysis of the experimental data indicated apparent relationships between processing time, geometry and surface response. Results indicate that material removal behaviour and roughness evolution may be geometry-dependent. Flat and convex surfaces appeared to follow expected transient-like and steady-state-like behaviour, whereas restricted geometries and intricate features exhibited distinct responses with characteristic transition times. Surface roughness reductions ranged from 36% to 89% depending on geometry. These findings provide preliminary quantitative insight into geometry-specific mass finishing behaviour, supporting improved process understanding and informing future optimisation of post-processing strategies for additively manufactured polymer components. Full article

(This article belongs to the Topic Engineered Surfaces and Tribological Performance)

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20 pages, 14508 KB

Open AccessFeature PaperArticle

Friction Properties and Surface Failure Mechanisms of Micro-Textured 7075 Aluminum Alloy Processed by Nanosecond Laser

by Fangcan Wei, Xiaofeng Wang, Yanming Zhu, Menghua Li, Fuli Zhang, Yiyi Fu and Xiaofan Deng

Coatings 2026, 16(6), 721; https://doi.org/10.3390/coatings16060721 - 17 Jun 2026

Viewed by 248

Abstract

In order to improve the poor wear resistance and adhesive wear of 7075 aluminum alloy under dry friction conditions, a nanosecond pulse laser was used to prepare surface micro-textures with different shapes, surface densities, and feature sizes. Subsequently, their friction and wear behavior, [...] Read more.

In order to improve the poor wear resistance and adhesive wear of 7075 aluminum alloy under dry friction conditions, a nanosecond pulse laser was used to prepare surface micro-textures with different shapes, surface densities, and feature sizes. Subsequently, their friction and wear behavior, as well as the corresponding failure mechanisms, were systematically investigated. Circular, square, and hexagonal micro-pit textures were selected as the research objects. Combined with surface morphology characterization, ball-on-disk dry wear tests, reciprocating friction tests, and contact stress and wear model analyses, the effects of texture parameters on tribological performance were systematically revealed. The results indicate that laser microtexturing can reduce the coefficient of friction on the surface of 7075 aluminum alloy to a certain extent and improve its wear resistance, with the friction-reducing effect closely related to the texture shape, areal density, and feature size. Among these, hexagonal texturing exhibited the best friction-reducing effect, while circular texturing demonstrated superior formation quality and friction stability. Compared to other specimens, the T8 group with a 7.5% areal density and a feature size of 100 µm exhibited the lowest average coefficient of friction. During the friction process, the microstructures gradually fail due to plastic flow filling, wear debris accumulation, and edge collapse. The research findings provide a reference for the optimized design and engineering applications of surface microstructures on aluminum alloys. Full article

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

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15 pages, 9000 KB

Open AccessFeature PaperArticle

Effect of Annealing in Air and Dry Nitrogen on MoOx Films Obtained by Magnetron Sputtering

by Marushka Sendova-Vassileva, Stanka Spasova, Aleksander Benkovsky, Vladimir Dulev and Simeon Topalski

Coatings 2026, 16(6), 720; https://doi.org/10.3390/coatings16060720 - 16 Jun 2026

Viewed by 200

Abstract

Substoichiometric molybdenum oxide is widely utilized as a hole transport layer (HTL) in polymer solar cells and perovskite solar cells. In this study, the possibility of developing MoOx layers applicable as HTLs with different characteristics by magnetron sputtering from a MoO₃ target [...] Read more.

Substoichiometric molybdenum oxide is widely utilized as a hole transport layer (HTL) in polymer solar cells and perovskite solar cells. In this study, the possibility of developing MoOx layers applicable as HTLs with different characteristics by magnetron sputtering from a MoO₃ target and annealing in dry nitrogen or air is explored. The optical transmission and reflection, optical band gap, FTIR and Raman spectra, crystallinity, conductivity, and work function of the films are studied depending on deposition and annealing conditions. The results demonstrate that it is possible to tune the properties of the obtained films with a view toward their application in solar cells. Full article

(This article belongs to the Section Thin Films)

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17 pages, 13102 KB

Open AccessArticle

Spin-Coated PCL/PVP Biofilms with Amniotic Membrane Matrix Enhance Proliferation and Migration of BM-MSC

by Juan de Dios Mendez Quezada, Antonio Rojas Murillo, Mario Simental-Mendía, Rodolfo Franco Marquez, Paulina Delgado Gonzalez, Jose F. Islas, Jorge Lara Arias, Celia N. Sanchez Dominguez, Hector Leija Gutierrez and Elsa N. Garza Treviño

Coatings 2026, 16(6), 719; https://doi.org/10.3390/coatings16060719 - 16 Jun 2026

Viewed by 257

Abstract

The amniotic membrane is widely recognized in regenerative medicine due to its rich content of extracellular matrix proteins and growth factors that confer anti-inflammatory and pro-regenerative properties. However, its rapid degradation restricts its standalone clinical use. To overcome these limitations, we developed biofilms [...] Read more.

The amniotic membrane is widely recognized in regenerative medicine due to its rich content of extracellular matrix proteins and growth factors that confer anti-inflammatory and pro-regenerative properties. However, its rapid degradation restricts its standalone clinical use. To overcome these limitations, we developed biofilms by incorporating decellularized human amniotic membrane matrix (dHAM) into polycaprolactone (PCL) and polyvinylpyrrolidone (PVP) matrices using spin-coating. Bone marrow-derived mesenchymal stem cells (BM-MSCs) were used to evaluate film biocompatibility through cell viability, proliferation, and wound healing migration assays. Surface characterization was performed using contact angle measurements, Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy, and scanning electron microscopy. Soluble dHAM extracts (4–6 mg/mL) significantly enhanced BM-MSC proliferation at 48 h compared to controls (p ≤ 0.01 and p ≤ 0.0001). Both PCL-dHAM and PVP-dHAM biofilms exhibited high cell viability (>90%) and improved initial adhesion. Notably, dHAM incorporation significantly increased wound closure rates at 24 h, reaching 98.47% for PCL-dHAM and 93.13% for PVP-dHAM, compared to 76.56% and 64.20% for pure polymers (p = 0.0001). All scaffolds maintained hydrophilic surfaces (<90°), favorable for cell interaction. The integration of dHAM into PCL and PVP by spin-coating produces biofilms biocompatible with enhanced regenerative potential, representing promising candidates for wound healing applications. In conclusion, these coatings support BM-MSC adhesion, proliferation, and migration, while significantly accelerating wound closure, underscoring their value as advanced bioactive coatings for regenerative medicine. Full article

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18 pages, 21433 KB

Open AccessArticle

In Situ Synthesized NbC-Reinforced Laser Clad Composite Coating on 17-4PH Stainless Steel: Microstructure Evolution and Wear Resistance Enhancement

by Chujie Qiao, Tianyu Wang and Zhenwei Li

Coatings 2026, 16(6), 718; https://doi.org/10.3390/coatings16060718 - 16 Jun 2026

Viewed by 233

Abstract

This study presents a novel in situ reinforcement strategy for 17-4PH stainless steel by using Nb and Cr₃C₂ powders as precursors, addressing the challenge of poor particle dispersion and interfacial bonding in conventional ex situ ceramic additions. The coatings were [...] Read more.

This study presents a novel in situ reinforcement strategy for 17-4PH stainless steel by using Nb and Cr₃C₂ powders as precursors, addressing the challenge of poor particle dispersion and interfacial bonding in conventional ex situ ceramic additions. The coatings were systematically compared with 17-4PH coatings without the addition of a reinforcing phase. The results show that the coating without Nb addition is dominated by α-Fe martensite, exhibiting a coarse columnar/dendritic microstructure. After adding Nb and Cr₃C₂, the coating successfully forms in situ face-centered cubic NbC, with a significantly refined and uniformly distributed microstructure. The 10 wt.% Nb+Cr₃C₂ coating exhibits a refined microstructure with an average grain size reduced from 1.12 μm to 0.85 μm and a microhardness of 495.5 HV, representing an 86% increase over the substrate and a 34% improvement compared to the unreinforced coating. Friction–wear tests demonstrate that the composite coating reduces wear track width and depth by approximately 50% and 45%, respectively, compared to the substrate, with the wear mechanism transitioning from severe adhesive and fatigue wear to mild abrasive wear and localized micro-delamination. In situ synthesized NbC effectively optimizes the coating microstructure, enhances interfacial bonding, and markedly improves the hardness and wear resistance of 17-4PH coatings, providing theoretical and technical support for their engineering application under severe service conditions. Full article

(This article belongs to the Section High-Energy Beam Surface Engineering and Coatings)

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15 pages, 24493 KB

Open AccessFeature PaperArticle

Development and Optimization of Dense Vertically Cracked Gd₂Zr₂O₇/8YSZ Bilayer Coatings for Improved Thermal Cycling Life

by Dianying Chen, Brian Keyes and Chris Dambra

Coatings 2026, 16(6), 717; https://doi.org/10.3390/coatings16060717 - 16 Jun 2026

Viewed by 273

Abstract

Advanced thermal barrier coatings (TBCs) are essential for improving the efficiency and performance of gas turbine engines. Increasing engine operating temperatures and harsh service environments are pushing the current industry-standard 8 wt% yttria-stabilized zirconia (8YSZ) to its performance limits. High-rare-earth-oxide zirconates, such as [...] Read more.

Advanced thermal barrier coatings (TBCs) are essential for improving the efficiency and performance of gas turbine engines. Increasing engine operating temperatures and harsh service environments are pushing the current industry-standard 8 wt% yttria-stabilized zirconia (8YSZ) to its performance limits. High-rare-earth-oxide zirconates, such as Gd₂Zr₂O₇, have emerged as promising materials for next-generation engines due to their excellent high-temperature phase stability, lower thermal conductivity, and enhanced resistance to CMAS attack. In this work, dense vertically cracked (DVC) Gd₂Zr₂O₇/8YSZ bilayer coatings were developed using the air plasma spray (APS) process. Two approaches were employed for deposition of the NiCrAlYHfSi bond coat: (i) high-velocity oxygen fuel (HVOF), and (ii) APS flash-coated HVOF NiCrAlYHfSi bond coat. The durability of DVC TBC systems with the two bond coat types was evaluated by furnace cycling test (FCT) at 1125 °C. The TBC system with an APS flash-coated HVOF bond coat exhibited an FCT lifetime approximately twice that of the system with the HVOF bond coat alone. The improvement is primarily attributed to the higher surface roughness of the APS flash-coated bond coat, which enhances resistance to crack initiation, propagation, and linkage, thereby extending thermal cycling life. Full article

(This article belongs to the Special Issue Thermal Barrier Coatings: Materials, Processes, Properties and Applications)

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1 pages, 116 KB

Open AccessCorrection

Correction: Chen et al. Effect of Substrates Characteristics on Tribological Behaviors of AlTiN-Based Coated WC–Co Cemented Carbides. Coatings 2022, 12, 1517

by Yi Chen, Li Zhang, Zhiqiang Zhong and Shanlin Wang

Coatings 2026, 16(6), 716; https://doi.org/10.3390/coatings16060716 - 16 Jun 2026

Viewed by 304

Abstract

In the original publication [...] Full article

20 pages, 4695 KB

Open AccessReview

Dual-Mechanism Synergistic Regulation and Performance Optimization of Lead Sulfide Quantum Dot Coatings in Optoelectronic Memristors

by Ru Li, Xinhe Jiang, Xuhao Zhao, Huiyun Zhang, Qingyu Xu and Guangyu Wang

Coatings 2026, 16(6), 715; https://doi.org/10.3390/coatings16060715 - 15 Jun 2026

Viewed by 386

Abstract

Lead sulfide quantum dots (PbS QDs), as a functional-layer coating, enable non-volatile integration and neuromorphic computing in memristive structures to address the von Neumann bottleneck. Herein, the dual-interface mechanism of PbS QDs in the memristor film structure is reviewed. First, the local electric [...] Read more.

Lead sulfide quantum dots (PbS QDs), as a functional-layer coating, enable non-volatile integration and neuromorphic computing in memristive structures to address the von Neumann bottleneck. Herein, the dual-interface mechanism of PbS QDs in the memristor film structure is reviewed. First, the local electric field enhancement effect generates tip electrode-like structures in the coating film through QD-mediated spatial charge gradients, thereby enabling precise control over the nucleation and growth of conductive filaments (CFs). As a result, the consistency of switching voltages and the thermal stability at elevated temperatures are significantly improved. Conversely, the anion reservoir effect exploits surface dangling bonds on QDs to efficiently capture anions from the dielectric layer, thereby synergistically regulating vacancy migration kinetics. This process enables zero-initialization behavior and ultra-low-power operation. In addition, the spatial distribution design and density modulation of QDs further reinforce both mechanisms. The structural optimization of QD/dielectric interface engineering can simultaneously improve cycling endurance and resistive switching uniformity. Furthermore, modification of QD surface chemistry through ligand decoration and passivation suppresses the stochasticity of ionic diffusion while improving the linearity of synaptic weight updates. This interfacial engineering strategy utilizing QDs as coating films advances the development of high-performance photonic–electronic systems for memory–computing convergence. Full article

(This article belongs to the Special Issue Structures and Coatings for High-Performance Photonics, Optoelectronics and Photovoltaics)

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50 pages, 16587 KB

Open AccessReview

Bioactive Components of Degradation Products from Biomedical Magnesium Alloys: Interactions with the In Vivo Microenvironment

by Yiming Ma, Hanbing Chen, Yuhang Yuan, Guang Yang and Jingan Li

Coatings 2026, 16(6), 714; https://doi.org/10.3390/coatings16060714 - 15 Jun 2026

Viewed by 385

Abstract

Magnesium is an extremely important macromineral in the human body. In recent years, magnesium and its alloys have been widely used in the biomedical field due to their excellent biocompatibility, degradability, and mechanical properties similar to those of human bone. Magnesium-based materials can [...] Read more.

Magnesium is an extremely important macromineral in the human body. In recent years, magnesium and its alloys have been widely used in the biomedical field due to their excellent biocompatibility, degradability, and mechanical properties similar to those of human bone. Magnesium-based materials can degrade completely within the human body, releasing magnesium ions, hydrogen gas, hydroxides, insoluble particles, and other bioactive substances, thereby influencing the microenvironment and the biochemical states of various cell types. This review systematically summarizes the biological effects of magnesium alloys in various microenvironments, analyzes the molecular mechanisms underlying the interactions between various bioactive components and their respective microenvironments, and finally explores strategies for optimizing magnesium alloy devices, thereby providing a reference for further research on the synergistic use of magnesium-based implants and drugs. Full article

(This article belongs to the Special Issue Advanced Alloy Degradation and Implants, 2nd Edition)

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3 pages, 156 KB

Open AccessEditorial

Editorial: Preparation and Applications of Bio-Based Polymer Coatings

by Emilia Mitkova Mihaylova

Coatings 2026, 16(6), 713; https://doi.org/10.3390/coatings16060713 - 15 Jun 2026

Viewed by 250

Abstract

The global coatings industry is undergoing a structural paradigm shift driven by the critical need for sustainable, eco-friendly, and high-performance alternatives to petroleum-derived materials [...] Full article

(This article belongs to the Special Issue Preparation and Applications of Bio-Based Polymer Coatings)

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