Coatings

15 pages, 1465 KB

Open AccessArticle

Enhancing PEEK Surface Bioactivity Through Phosphate and Calcium Ion Functionalization

by Lillian V. Tapia-Lopez, Antonia Luna-Velasco, Carlos A. Martínez-Pérez, Simón Yobanny Reyes-López and Javier S. Castro-Carmona

Coatings 2025, 15(11), 1359; https://doi.org/10.3390/coatings15111359 - 20 Nov 2025

Viewed by 386

Abstract

Inert polymeric implants must evolve to enhance their biological interactions with host tissue, triggering positive cellular responses and promoting tissue bonding and integration. Poly-ether-ether-ketone (PEEK) is widely used as an implant material; however, its inert nature results in limited biological interactions. Various surface [...] Read more.

Inert polymeric implants must evolve to enhance their biological interactions with host tissue, triggering positive cellular responses and promoting tissue bonding and integration. Poly-ether-ether-ketone (PEEK) is widely used as an implant material; however, its inert nature results in limited biological interactions. Various surface modification techniques have been investigated to enhance its bioactivity and overall biological performance. In this study, the PEEK surface was bioactivated through a chemical treatment involving two steps: surface activation using low-pressure oxygen plasma, followed by biofunctionalization with phosphate and calcium ions. Comprehensive surface characterization by contact angle, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared (FT-IR) confirmed the effect of plasma and the ionic surface incorporation. The biological response was evaluated through cell viability, adhesion, and proliferation in NIH/3T3 fibroblasts and HOS osteoblasts, and the results indicated the efficacy of the surface modifications. Therefore, the proposed treatments provide an efficient strategy to improve the biological performance of PEEK-based implants. Full article

(This article belongs to the Special Issue Surface Coating, Functionalization, and Characterization of Cell- and Tissue-Based Biomaterials)

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25 pages, 21144 KB

Open AccessArticle

Study on Improving the Stability of Steel Slag Fine Aggregate by Boiling Pretreatment Combined with Microbial Mineralization

by Zhe Wang, Haihe Yi, Whenyu Du, Dachao Jiang, Yonghua Jiao, Hongyi Zhao and Tian Su

Coatings 2025, 15(11), 1358; https://doi.org/10.3390/coatings15111358 - 20 Nov 2025

Viewed by 406

Abstract

The volume stability of steel slag fine aggregate (SSFA) is poor due to the hydration expansion of f-CaO/f-MgO, which limits its resource utilization. In this paper, a green modification route combining simple boiling water pretreatment with carbonic anhydrase (CA) -mediated microbial mineralization (MICP) [...] Read more.

The volume stability of steel slag fine aggregate (SSFA) is poor due to the hydration expansion of f-CaO/f-MgO, which limits its resource utilization. In this paper, a green modification route combining simple boiling water pretreatment with carbonic anhydrase (CA) -mediated microbial mineralization (MICP) was proposed and evaluated from macro–micro multi-scale. Compared with direct carbonization, CA-MICP accelerated CO₂ hydration and carbonate precipitation. Boiling water pretreatment enhanced ion release and pore accessibility, and the two synergistically improved the reaction kinetics. At 0.3 MPa, 100 h boiling pretreatment combined with 12 h microbial mineralization (K8 group) performed best: CO₂ absorption rate reached 4.98%, carbonization rate reached 3.93%; the content of f-CaO and f-MgO decreased to 0.16% and 0.12% (conversion rate 91.82% and 87.43%), respectively. The linear expansion of SSFA mortar decreased to 0.0176% after 55 h of water bath. XRD/FTIR showed that the carbonate peak was enhanced and the O-H characteristics were weakened. The weight loss of TG-DTG at 600–800 °C increased. SEM/BET observed that flake/cluster carbonates filled the pores and increased the interface density. Innovations: For the first time, the synergistic effect of boiling water pretreatment and CA-MICP was verified in the steel slag fine aggregate system, and a feasible process window was given to efficiently convert expansive oxides into stable carbonates, significantly improve volume stability, and provide a feasible path for the high-value utilization of SSFA. Full article

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

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21 pages, 7671 KB

Open AccessArticle

Microstructure and Properties of Biomedical Mg-Zn-Ca-Ag Alloy and the Micro-Arc Oxidation Coatings

by Wei-Gang Lv, Ze-Xin Wang, Zi-Meng Xiao, Shu-Fan Zhou, Jun Ma, Liang-Yu Chen, Sheng Lu and Dubovyy Oleksandr

Coatings 2025, 15(11), 1357; https://doi.org/10.3390/coatings15111357 - 20 Nov 2025

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Abstract

This study investigates the influence of Ag addition on the microstructure, mechanical behavior, corrosion resistance, and antibacterial performance of Mg-Zn-Ca-Ag alloys and their micro-arc oxidation (MAO) coatings. Four casting alloys containing 0.2, 0.4, 0,6 and 0.8 wt.% Ag were fabricated and characterized by [...] Read more.

This study investigates the influence of Ag addition on the microstructure, mechanical behavior, corrosion resistance, and antibacterial performance of Mg-Zn-Ca-Ag alloys and their micro-arc oxidation (MAO) coatings. Four casting alloys containing 0.2, 0.4, 0,6 and 0.8 wt.% Ag were fabricated and characterized by SEM, XRD, and TEM. The microstructure consisted mainly of α-Mg, Mg₂Ca, Mg₇Zn₃, and Mg₆Ca₂Zn₃ phases, and the elastic modulus (~25.8 GPa) was comparable to that of human bone. MAO coatings produced in a bio-functional electrolyte exhibited pit-like morphologies due to Ag-induced melt fluidity and self-sealing effects. The coatings were composed primarily of MgO, Mg₂SiO₄, Ca₃(PO₄)₂, CaCO₃, and Ag₂O, with the ZQ 0.8-MAO sample showing the highest Ca/P ratio (1.75), indicative of superior bioactivity. Electrochemical impedance spectroscopy revealed optimal corrosion resistance (2.56 × 10⁴ Ω·cm²), while antibacterial efficiency exceeded 96%. Overall, Ag alloying enhanced both the bulk and surface properties of Mg-Zn-Ca alloys, yielding robust, corrosion-resistant, and antibacterial coatings with excellent biocompatibility-highlighting their potential for biodegradable orthopedic implant applications. Full article

(This article belongs to the Section Bioactive Coatings and Biointerfaces)

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17 pages, 7491 KB

Open AccessArticle

Performance Reinforcement of Basalt Fiber–Reinforced Polymer by Guiding Hierarchical Aramid/Zirconia Hybrid Fiber

by Ziteng Zhou, Buerke Yang, Jiaxin He, Xiang Yuan, Fei Cheng, Peng Zhang, Shuying Shi, Evgeny Lomakin, Daria Bondarchuk, Rasuljon Tojiyev, Hao Liu and Xiaozhi Hu

Coatings 2025, 15(11), 1356; https://doi.org/10.3390/coatings15111356 - 20 Nov 2025

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Abstract

Hierarchical aramid/zirconia hybrid fibers were introduced into the interlayers of basalt fiber–reinforced polymer (BFRP) composites to optimize their interlaminar properties. The reinforcing effect of micro/nano aramid short fiber (MNASF) and zirconia fiber (ZF) on BFRP composites at different mass ratios was investigated through [...] Read more.

Hierarchical aramid/zirconia hybrid fibers were introduced into the interlayers of basalt fiber–reinforced polymer (BFRP) composites to optimize their interlaminar properties. The reinforcing effect of micro/nano aramid short fiber (MNASF) and zirconia fiber (ZF) on BFRP composites at different mass ratios was investigated through three-point bending (3PB) tests and compression tests. The results demonstrated that the BFRP composites incorporating 2 wt.% MNASF and 2 wt.% ZF exhibited the most significant property enhancement. The 3PB tests revealed increases in flexural strength and modulus of 119.2% and 62.6%, respectively, compared to the unreinforced BFRP composites. Compression tests showed that this specific formulation enhanced the compressive strength and modulus by 257.7% and 121.6%, respectively. Scanning electron microscopy and optical microscopy observations indicated that the incorporation of MNASF and ZF effectively reduced the volume fraction of resin-rich regions in the interlaminar regions, and the dominant failure mode transitioned from delamination to shear failure. Overall, the introduction of MNASF and ZF effectively combined the reinforcing effects of the two fibers, improving the mechanical properties of BFRP composites. Full article

(This article belongs to the Special Issue Surface Engineering of Composites Coatings: Enhancing Mechanical and Functional Properties)

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12 pages, 3212 KB

Open AccessArticle

Fast Joining of the 40Cr/WC-8Co Combination with Ag28Cu Interlaer Through the Spark Plasma Sintering Process

by Shenggang Wang, Chang Yu, Xuanyi Lin and Haitao Xu

Coatings 2025, 15(11), 1355; https://doi.org/10.3390/coatings15111355 - 20 Nov 2025

Viewed by 211

Abstract

The solid joining between the WC-8Co cemented carbide and alloy steels has great significance for their extensive applications. In this study, the WC-8Co and 40Cr steel were joined with the Ag-28Cu interlayer through the SPS method. The microstructure and mechanical properties of the [...] Read more.

The solid joining between the WC-8Co cemented carbide and alloy steels has great significance for their extensive applications. In this study, the WC-8Co and 40Cr steel were joined with the Ag-28Cu interlayer through the SPS method. The microstructure and mechanical properties of the joints obtained at three temperatures—740 °C, 760 °C, and 780 °C—were analyzed. The joining mechanism was studied, and the relationship between the microstructure and shear strength of the joints was also revealed. When processed at 740 °C, the poor bonding between the interlayer and the 40Cr substrates damaged the joint strength. Higher bonding temperature helped to eliminate the interfacial defects. The joint bonded at 760 °C consists mainly of Ag, Cu within the interlayer and Co-rich Fe(s,s) at the substrate/interlayer interfaces, without any defects. In such a case, the shear strength of the joints reached the maximum level of 236 MPa. However, the increased residual stresses at higher bonding temperatures (780 °C) spoiled the strength of the joints, resulting in the decreasing of the shear strength to 173 MPa. The study shed light on the fast joining of the WC-Co and alloy steels at relatively low temperatures. Full article

(This article belongs to the Special Issue Surface Modification Techniques Utilizing Plasma and Photonic Methods)

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25 pages, 7923 KB

Open AccessArticle

Thermal Analysis and Parameter Optimization of the Ironing Process for FDM-Printed PLA and ABS Parts

by Chaoda Chen, Xuan Lu, Renfei Hu, Zeping Xiao, Rulin Chen, Caiming Zhong and Jindong Yu

Coatings 2025, 15(11), 1354; https://doi.org/10.3390/coatings15111354 - 20 Nov 2025

Viewed by 320

Abstract

The surface roughness of fused deposition modeling (FDM) parts severely limits their applications. Ironing, as an effective method to enhance surface quality, exhibits unclear interactions among its process parameters and lacks defined optimal process windows for different materials. To address this, this study [...] Read more.

The surface roughness of fused deposition modeling (FDM) parts severely limits their applications. Ironing, as an effective method to enhance surface quality, exhibits unclear interactions among its process parameters and lacks defined optimal process windows for different materials. To address this, this study employs a simulation to reveal the influence of ironing speed on the temperature field. Combining single-factor experiments with response surface methodology, predictive models for the surface roughness of PLA and ABS are established. Results indicate significant parameter interactions: PLA roughness is primarily governed by the interaction between ironing speed and ironing flow, while ABS roughness is co-influenced by the main effects of all three parameters (ironing speed, ironing flow, and ironing line spacing) as well as the interactions between speed and flow, and speed and line spacing. After optimization, the optimal surface roughness Ra values for PLA and ABS parts reached 0.852 μm and 1.014 μm, respectively. This study clarifies the dependence of ironing process effectiveness on material properties at the experimental optimization level, providing a theoretical basis for precise control of the FDM ironing process. Full article

(This article belongs to the Special Issue Manufacturing and Surface Engineering, 5th Edition)

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16 pages, 3844 KB

Open AccessArticle

Surface Damage and Fouling Resistance Degradation Mechanisms of Silicone Antifouling Coatings Under Sediment Erosion

by Chao Li, Wei Chen, Peng Zhang, Liang Jiao and Songgui Chen

Coatings 2025, 15(11), 1353; https://doi.org/10.3390/coatings15111353 - 20 Nov 2025

Viewed by 373

Abstract

Sediment-laden seawater (1.4 kg/m³) under controlled flow velocities (1.5 m/s and 3.0 m/s) was employed to evaluate degradation mechanisms in static anti-fouling coatings. Exposure to 1.5 m/s sediment-laden flow induced a 49% reduction in adhesion strength, a 4.9–5.2° decrease in water [...] Read more.

Sediment-laden seawater (1.4 kg/m³) under controlled flow velocities (1.5 m/s and 3.0 m/s) was employed to evaluate degradation mechanisms in static anti-fouling coatings. Exposure to 1.5 m/s sediment-laden flow induced a 49% reduction in adhesion strength, a 4.9–5.2° decrease in water contact angle, and an elevation in surface roughness from 0.32 μm to 0.88 μm after 30 days. Concurrently, antibacterial rate and anti-algal rate declined by 11.9% and 14.6%, respectively. In comparison, pure seawater scouring at equivalent velocity reduced adhesion by 30% and contact angle by merely 1.1°. Low-flow (1.5 m/s) conditions accelerated abrasive wear, driving severe surface roughening, whereas higher flow velocity (3.0 m/s) disrupted sustained particle–coating contact through turbulence generation, attenuating roughness progression. Crucially, low-flow conditions intensified abrasive wear and promoted severe surface roughening, whereas higher flow velocities generated sufficient turbulence to disrupt sustained particle–coating contact, thereby slowing the progression of roughness. These findings reveal a previously unrecognized, flow-velocity-dependent erosion mechanism: lower velocities encourage particle deposition and progressive surface damage, while higher velocities unexpectedly produce a protective, turbulence-mediated buffering effect that mitigates surface roughening. These findings establish a theoretical foundation for developing advanced anti-fouling coatings with enhanced resistance to sediment erosion. Full article

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

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14 pages, 1914 KB

Open AccessArticle

Microstructure Regulation and Optoelectronic Performance Optimization of Flexible CPI-Based ITO Thin Films Under Low-Temperature Heat Treatment Process

by Hanyan Zhang, Ruohe Yao, Weijing Wu and Yi Shen

Coatings 2025, 15(11), 1352; https://doi.org/10.3390/coatings15111352 - 19 Nov 2025

Viewed by 269

Abstract

Addressing the urgent need for low-temperature processes in the manufacturing of flexible vehicle-mounted touch display devices, this study investigates the process–structure–performance relationships of indium tin oxide (ITO) thin films prepared by DC magnetron sputtering on transparent polyimide (CPI) substrates. A synergistic strategy of [...] Read more.

Addressing the urgent need for low-temperature processes in the manufacturing of flexible vehicle-mounted touch display devices, this study investigates the process–structure–performance relationships of indium tin oxide (ITO) thin films prepared by DC magnetron sputtering on transparent polyimide (CPI) substrates. A synergistic strategy of “low-temperature deposition (110 °C)–230 °C atmospheric annealing” was employed. The optimal sample exhibited excellent comprehensive performance: a resistivity as low as 203 μΩ·cm, an average visible light transmittance of 89.2%, a surface roughness of 0.76 nm, and the ability to endure 100,000 bending cycles at a radius of R = 5 mm with a sheet resistance change rate of less than 10%. Microstructural and chemical state analyses revealed that this process facilitates the complete oxidation of Sn²⁺ to Sn⁴⁺ (Sn⁴⁺/Sn²⁺ ratio of 8.2:1) and the controlled formation of oxygen vacancies (O_L/O_V ratio of 6.5:1), leading to a synergistic improvement in carrier concentration (8.7 × 10²⁰ cm⁻³) and mobility (35.2 cm²/V·s). This work elucidates the crystallization kinetics and doping mechanisms under low-temperature conditions, providing a viable low-temperature technical pathway for the fabrication of high-performance transparent electrodes in flexible electronics. Full article

(This article belongs to the Special Issue Advanced Coating Technology by Physical Vapor Deposition and Applications)

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34 pages, 99537 KB

Open AccessArticle

Microchemical Analysis of Rammed Earth Residential Walls Surface in Xiaochikan Village, Guangdong

by Liang Zheng, Qingnian Deng, Jingwei Liang, Zekai Guo, Yufei Zhu, Wei Liu and Yile Chen

Coatings 2025, 15(11), 1351; https://doi.org/10.3390/coatings15111351 - 19 Nov 2025

Cited by 1 | Viewed by 328

Abstract

Xiaochikan Village, located in Guangdong Province in South China, is one of the few remaining traditional rammed earth dwellings of the Cantonese ethnic group in the Lingnan region. However, the influence of Zhuhai’s subtropical maritime monsoon climate has led to continuous physical and [...] Read more.

Xiaochikan Village, located in Guangdong Province in South China, is one of the few remaining traditional rammed earth dwellings of the Cantonese ethnic group in the Lingnan region. However, the influence of Zhuhai’s subtropical maritime monsoon climate has led to continuous physical and chemical erosion of the rammed earth walls. For example, cracking occurs due to high temperatures and heavy rain, accelerated weathering occurs due to salt spray deposition, and biological erosion occurs due to high humidity and high temperatures. Therefore, two experimental analysis techniques, X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive spectrometer (SEM-EDS), were used to explore the structural anti-erosion mechanism of the ancient, rammed earth buildings in Xiaochikan Village. The results show that (1) the morphological characteristics of the east and west walls of the rammed earth dwellings in Xiaochikan Village are more similar. The particles on the east wall are regular spherical or polygonal, small, and evenly distributed, while the particles on the west wall are mainly spherical and elliptical, with consistent size and less agglomeration. The surfaces of the particles on both walls are relatively smooth and flat. (2) The core element bases of the four wall samples are consistent, with C, Si, Al, Ca, and Fe as the core, accounting for more than 93%, reflecting the base characteristics of the local alluvial soil “silicate skeleton–carbonate cementation–organic matter residue” and reflecting the “local material” attribute of rammed earth. Except for the south wall sample, the Cl content of the remaining samples exceeds 1%. In the thermal map, Cl shows “pore/interstitial enrichment”, which confirms that the salinization process of marine aerosols with rainwater infiltration and evaporation residue is a common influence of marine climate. (3) The rammed earth walls in Xiaochikan Village consist of three main minerals: Quartz (SiO₂, including alpha-type SiO₂), Calcite (CaCO₃, including synthetic calcite), and Gibbsite (Al(OH)₃). Full article

(This article belongs to the Special Issue New Insights into Earthen Site Conservation: Methods, Techniques, Management, and Key Case Studies)

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7 pages, 174 KB

Open AccessEditorial

Summary of Publications in the Special Issue: Advances in Corrosion Resistant Coatings

by Yong X. Gan

Coatings 2025, 15(11), 1350; https://doi.org/10.3390/coatings15111350 - 19 Nov 2025

Viewed by 357

Abstract

This editorial provides an outline of publications in the Special Issue on corrosion resistance coatings [...] Full article

(This article belongs to the Special Issue Advances in Corrosion Resistant Coatings)

25 pages, 4830 KB

Open AccessArticle

Self-Cleaning Road Marking Paints for Improved Road Safety: Multi-Scale Characterization and Performance Evaluation Using Rhodamine B and Methylene Blue as Model Pollutants

by Orlando Lima, Jr., Iran Rocha Segundo, Laura Mazzoni, Elisabete Freitas and Joaquim Carneiro

Coatings 2025, 15(11), 1349; https://doi.org/10.3390/coatings15111349 - 19 Nov 2025

Viewed by 339

Abstract

Throughout the lifetime, road markings (RMs) accumulate dirt, oils, and greases, which reduce visibility, shorten service life, and compromise road safety. If RMs could degrade these pollutants, their service life would increase. When exposed to UV light and humidity, semiconductors, such as titanium [...] Read more.

Throughout the lifetime, road markings (RMs) accumulate dirt, oils, and greases, which reduce visibility, shorten service life, and compromise road safety. If RMs could degrade these pollutants, their service life would increase. When exposed to UV light and humidity, semiconductors, such as titanium dioxide (TiO₂), can interact with contaminants and promote their chemical degradation. Semiconductors are commonly used on different types of substrates to achieve self-cleaning ability. In this study, 0.25–3 wt% TiO₂ was incorporated into a commercial RM paint for this purpose. After functionalization, the RM paint samples were contaminated with Methylene Blue and Rhodamine B. After pollution, the specimens were irradiated with a light source that simulates sunlight. To assess the self-cleaning capacity of the paints, visual analysis, color variation and discoloration by using CIELAB color coordinates, diffuse reflectance, and digital image processing techniques were applied. In both techniques, the samples with 2% and 3% of TiO₂ showed a greater capacity to degrade pollutants. Further, the chemical and morphological characteristics of the reference paint and the samples that showed the best self-cleaning results were analyzed by using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), and X-ray Diffraction (XRD). They identified the polymer, filler, and pigment in the commercial paint and confirmed the TiO₂ increase after functionalization. This study demonstrated the innovative potential of incorporating semiconductors to achieve a new capability (self-cleaning) for RM paints. This breakthrough not only has the potential to extend the RM service life, but also to improve road safety through greater visibility. Full article

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

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17 pages, 6617 KB

Open AccessArticle

Ultrahigh-Speed Deposition of Diamond-like Carbon on a Pipe Surface Using a Scanning Deposition Method via Local High-Density Plasma

by Akihiko Ito, Masahiro Esaki, Su-Min Bae, Taketo Nagai, Hiroyuki Kousaka and Toru Harigai

Coatings 2025, 15(11), 1348; https://doi.org/10.3390/coatings15111348 - 19 Nov 2025

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Abstract

This study presents a highly effective method for depositing diamond-like carbon (DLC) films onto pipe substrates using a scanning deposition by plasma enhanced chemical vapor deposition. A microwave–sheath voltage combination plasma was employed to generate local high-density plasma along a rotating pipe. While [...] Read more.

This study presents a highly effective method for depositing diamond-like carbon (DLC) films onto pipe substrates using a scanning deposition by plasma enhanced chemical vapor deposition. A microwave–sheath voltage combination plasma was employed to generate local high-density plasma along a rotating pipe. While conventional contact-mode deposition using a metal contactor suffers from arcing and surface damage due to unstable sliding contact during rotation, a non-contact deposition using a metal antenna was developed to overcome these limitations. Electromagnetic field simulations were conducted to evaluate microwave power absorption in various antenna geometries, showing that the flat-plate antenna demonstrated the most effective power coupling. Subsequent scanning deposition experiments to a rotating pipe using flat-plate antennas of different lengths revealed that the 100 mm configuration achieved the highest deposition volume rate (exceeding that of the contact-mode) while avoiding arcing. Optical emission observations during deposition confirmed the formation of high-density plasma surrounding the flat-plate antenna and Raman spectroscopy of the deposited film showed typical spectra of DLC films. The deposition rates of DLC-coated pipe showed no significant variation with respect to rotational angle, suggesting that rotation during deposition contributes to achieving uniform film thickness along the circumferential direction of the pipe. Full article

(This article belongs to the Special Issue Plasma Coating and Interface Technology: New Horizons in Surface Science)

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38 pages, 14961 KB

Open AccessReview

Research Status and Progress on the Current-Carrying Friction and Wear Performance of Conductive Slip Rings in Harsh Environments

by Hailin Wu, Xinze Zhao, Wanting Li, Yang Li, Tengda Pan, Wei Yang and Xuetao Li

Coatings 2025, 15(11), 1347; https://doi.org/10.3390/coatings15111347 - 19 Nov 2025

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Abstract

With the rapid development of aerospace, industrial automation, and weapons manufacturing, the performance requirements for conductive slip rings have become more stringent, and their operating environments have become increasingly harsh, making the study of the effects of harsh environmental conditions on slip rings [...] Read more.

With the rapid development of aerospace, industrial automation, and weapons manufacturing, the performance requirements for conductive slip rings have become more stringent, and their operating environments have become increasingly harsh, making the study of the effects of harsh environmental conditions on slip rings particularly important. This paper systematically reviews the effects of harsh environments on the current-carrying friction and wear behavior of slip rings, with a detailed discussion on the mechanisms by which environmental factors such as high temperature, humidity, corrosive gases, and vacuum influence the tribological properties of slip ring materials. Research has shown that these harsh environments significantly change the friction coefficient, wear rate, and electrical contact performance of slip rings, causing degradation of material properties. By reviewing current experimental studies and numerical simulations, this paper analyzes the performance variations and failure mechanisms of slip rings in various environments, summarizing the key technological progress in enhancing slip ring performance under such conditions, particularly the application of material modification and surface coating technologies. Additionally, concerning the lifetime prediction and monitoring of slip ring systems, this paper explores the potential of multiphysics simulation technology and intelligent monitoring methods. Finally, this paper looks forward to future research directions, including optimization design based on multiphysics simulation, the development of high-temperature coatings, the improvement of lifetime prediction models, and the optimization of thermal management strategies, aiming to provide theoretical support and technical guidance for enhancing the reliability and durability of slip rings in extreme environments. Full article

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

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11 pages, 2509 KB

Open AccessArticle

Hydrothermal Carbonization Coating on AISI 1018 Steel for Seawater Corrosion Protection

by Yong X. Gan

Coatings 2025, 15(11), 1346; https://doi.org/10.3390/coatings15111346 - 19 Nov 2025

Viewed by 295

Abstract

The seawater corrosion behavior of a plain carbon steel covered with hydrothermally carbonized coating was studied. Hydrothermal carbonization of sugar (sucrose) dissolved in water with a concentration of 10 wt.% at 200 °C for 4 h was carried out to produce a carbonized [...] Read more.

The seawater corrosion behavior of a plain carbon steel covered with hydrothermally carbonized coating was studied. Hydrothermal carbonization of sugar (sucrose) dissolved in water with a concentration of 10 wt.% at 200 °C for 4 h was carried out to produce a carbonized coating on the steel. The corrosion resistance of the steel with and without the carbonized coating was evaluated by polarization tests in seawater. The Tafel slopes were calculated using polarization data. The corrosion current and the potential of corrosion were determined to examine the effect of the carbonized coating on the corrosion behavior of the steel. In addition, AC impedance measurements on the steel without and with the hydrothermal carbonization coating were performed in a three-electrode cell with a Ag/AgCl reference electrode, platinum counter electrode, and seawater electrolyte. It was found that hydrothermal carbonization of sugar generated a continuous carbon-rich layer on the surface of the steel. This carbon layer is highly corrosion-resistant as shown by the decrease in the corrosion current. It is concluded that the hydrothermally carbonized coating has the nature of passivation films, and it can slow down the corrosion rate of the plain carbon steel in seawater. The impedance of the steel without hydrothermal carbonization coating is very low. With hydrothermal carbonization coating, an increase in the resistance and the capacitive response of the coating/seawater interface was observed. Full article

(This article belongs to the Special Issue Advances in Corrosion-Resistant Coatings, 2nd Edition)

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14 pages, 2123 KB

Open AccessArticle

Enhanced Corrosion Protection of Copper Using Nitrogen-Doped Graphene Coatings Synthesized by Chemical Vapor Deposition

by Zhasulan Nakysbekov, Bauyrzhan Zhumadilov, Gulmaira Partizan, Botagoz Medyanova, Daniyar Ismailov, Valentina Grichshenko, Dinara Akhmetsadyk, Bakhodir Aliyev and Laura Mustafa

Coatings 2025, 15(11), 1345; https://doi.org/10.3390/coatings15111345 - 19 Nov 2025

Viewed by 382

Abstract

In this study, nitrogen-doped graphene (NG) films were synthesized on copper foil sur-faces by chemical vapor deposition (CVD), and their anti-corrosion properties were comprehensively investigated. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) results showed that the graphene layer was uniformly formed [...] Read more.

In this study, nitrogen-doped graphene (NG) films were synthesized on copper foil sur-faces by chemical vapor deposition (CVD), and their anti-corrosion properties were comprehensively investigated. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) results showed that the graphene layer was uniformly formed and nitrogen atoms were successfully incorporated. Raman spectroscopy revealed that the sample obtained on a 30 μm thick copper foil had a high structural quality (low ID/IG value). Electrochemical measurements showed that the NG coatings significantly reduced the corrosion current density and rate compared to pure copper. In short-term tests, the highest inhibition efficiency (91.5%) was observed for the sample synthesized on a 200 μm thick copper foil. In long-term (up to 2 months) seawater immersion tests, the inhibition efficiency decreased slightly over time, but the NG coatings showed much higher anti-corrosion properties than pure copper at all times. Overall results proved that nitrogen-doped graphene is a potential material in protecting metals from long-term corrosion, not only in seawater but also in harsh environments. Full article

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

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16 pages, 4377 KB

Open AccessArticle

Effect of Hydroxyapatite Post-Treatment on the Corrosion Resistance, Cytocompatibility and Antibacterial Properties of Copper-Containing Micro Arc Oxidation Coatings on Mg Alloy as Oral GBR Membrane Application

by Tingting Ma, Qiang Chen, Qian Zhang, Yu Xu, Sharafadeen Kunle Kolawole, Muhammad Ali Siddiqui, Honghui Cheng and Junxiu Chen

Coatings 2025, 15(11), 1344; https://doi.org/10.3390/coatings15111344 - 19 Nov 2025

Viewed by 316

Abstract

Biodegradable magnesium (Mg) alloys hold promising application prospects in the field of guided bone regeneration (GBR) membranes, particularly for oral and maxillofacial applications. However, their corrosion resistance requires further improvement. Additionally, Mg alloys are susceptible to bacterial infection upon implantation, while copper (Cu) [...] Read more.

Biodegradable magnesium (Mg) alloys hold promising application prospects in the field of guided bone regeneration (GBR) membranes, particularly for oral and maxillofacial applications. However, their corrosion resistance requires further improvement. Additionally, Mg alloys are susceptible to bacterial infection upon implantation, while copper (Cu) is known for its excellent antibacterial properties. Introducing Cu into the micro-arc oxidation (MAO) coating can enhance both the corrosion resistance and antibacterial performance of Mg alloys. However, the sealing effect of such coatings remains suboptimal. Hydroxyapatite (HA), which possesses outstanding bioactivity, is a promising bone substitute material. This study investigates the influence of HA content on the microstructure, corrosion resistance, cytotoxicity, and antibacterial properties of Cu-containing MAO coatings. The results demonstrate that as the HA concentration increases, the corrosion resistance of the composite coating is significantly enhanced. The corrosion rate decreased from 0.32 mm/y for the untreated MAO coating to 0.27 mm/y and 0.23 mm/y for the HA-treated samples with EDTA–Ca concentrations of 125 mmol/L and 175 mmol/L, respectively. Cytotoxicity assessment indicates that the incorporation of an HA layer significantly improves cell compatibility compared to the bare MAO coating. However, the enhanced corrosion resistance provided by the denser HA layer (at 175 mmol/L EDTA–Ca) unfortunately acts as a barrier, limiting the release of antibacterial Cu²⁺. Among the coatings tested, the one with 125 mmol/L EDTA–Ca exhibited the best overall performance, demonstrating good corrosion resistance, cytocompatibility, and effective antibacterial properties. Full article

(This article belongs to the Special Issue Advanced Coatings for Alloy Protection and Performance Enhancement)

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19 pages, 2172 KB

Open AccessReview

Preparation and Classification of Coatings by High-Energy Ball Milling: A Review

by Zhanfeng Qi, Hengye Zhang, Xiuli Guo and Le Geng

Coatings 2025, 15(11), 1343; https://doi.org/10.3390/coatings15111343 - 19 Nov 2025

Viewed by 573

Abstract

High-energy ball milling (HEBM) offers a pathway for the green preparation of multifunctional coatings. However, existing research lacks systematic frameworks addressing the interplay of HEBM process parameters, elemental screening criteria, and coating classification systems. This study establishes a comprehensive “elemental screening–process synergy–classification and [...] Read more.

High-energy ball milling (HEBM) offers a pathway for the green preparation of multifunctional coatings. However, existing research lacks systematic frameworks addressing the interplay of HEBM process parameters, elemental screening criteria, and coating classification systems. This study establishes a comprehensive “elemental screening–process synergy–classification and prediction” framework for HEBM coatings. Key contributions include establishing a two-tier screening criterion based on non-radioactivity/low-toxicity and functionality for coating elements; revealing the synergistic effects of key process parameters; proposing a dual-dimensional coating classification system based on composition and function; and constructing a quantitative database encompassing 11 key performance indicators. This work provides theoretical foundations and data-driven guidance for the precise design and selection of high-performance HEBM coatings. Full article

(This article belongs to the Special Issue Advances in Alloy Surface Mechanics: The Effects of Coating Technologies on Performance)

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3 pages, 135 KB

Open AccessEditorial

Flame Retardant Coatings for Plastics and Textiles

by Giulio Malucelli

Coatings 2025, 15(11), 1342; https://doi.org/10.3390/coatings15111342 - 18 Nov 2025

Viewed by 337

Abstract

The growing use of polymer-based materials in transportation, construction, electronics, and textiles presents a significant challenge due to their inherent flammability [...] Full article

(This article belongs to the Special Issue Flame Retardant Coatings for Plastics and Textiles)

18 pages, 10563 KB

Open AccessArticle

Biological Response and Antimicrobial Behaviour of Sputtered TiO₂/Cu Coatings Deposited on Ti6Al4V Alloy

by Maria P. Nikolova, Yordan Handzhiyski, Tanya V. Dimitrova, Andreana Andreeva, Stefan Valkov, Maria Ormanova and Margarita D. Apostolova

Coatings 2025, 15(11), 1341; https://doi.org/10.3390/coatings15111341 - 18 Nov 2025

Viewed by 278

Abstract

Nanostructured TiO₂/Cu coatings were deposited on Ti6Al4V alloy by a two-step glow-discharge sputtering process and evaluated for their structural, electrochemical, and biological properties. Dual-acid etching produced microroughened substrates before TiO₂ layer deposition, followed by surface Cu sputtering with varied deposition [...] Read more.

Nanostructured TiO₂/Cu coatings were deposited on Ti6Al4V alloy by a two-step glow-discharge sputtering process and evaluated for their structural, electrochemical, and biological properties. Dual-acid etching produced microroughened substrates before TiO₂ layer deposition, followed by surface Cu sputtering with varied deposition times. Characterisation by AFM, OM, SEM/EDS, and XRD confirmed the formation of TiO₂ with Cu/Cu₂O-containing hybrid coatings with good adhesion to the substrate. Increasing Cu deposition enhanced surface hydrophobicity and copper ion release. EIS measurements proved that the coatings retained stable protective behaviour in simulated body fluid (SBF). Antibacterial tests against Escherichia coli showed up to 98% improved efficacy compared to bare Ti6Al4V, confirming the strong antimicrobial role of copper. However, MG63 osteoblast-like cells exhibited reduced viability even after pre-immersion in PBS, suggesting that cytotoxicity was associated not only with excess Cu ion release but also with direct interaction between cells and surface Cu nanostructures. Overall, the results indicate that TiO₂/Cu coatings provide excellent antimicrobial activity, good protection and strong adhesion, but their limited biocompatibility highlights the need for fine-tuned copper incorporation in future biomedical implant applications. Full article

(This article belongs to the Special Issue Coatings for Biomedical Applications: Biocompatibility, Drug Delivery, Antibiosis and Tissue Engineering)

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23 pages, 7900 KB

Open AccessArticle

Effect of Protrusions on the Falling Film Flow and Heat Transfer of Oily Wastewater Outside an Elliptical Tube

by Yiqi Lu, Hao Lu, Wenjun Zhao, Chuanxiao Zheng and Yajie Li

Coatings 2025, 15(11), 1340; https://doi.org/10.3390/coatings15111340 - 18 Nov 2025

Viewed by 259

Abstract

This study addresses the optimized design of falling-film heat exchanger tubes, aiming to enhance heat transfer efficiency and reduce thermal losses, thereby offering potential pathways for efficient green energy utilization. Ten tube models were established and analyzed using computational fluid dynamics (CFD) under [...] Read more.

This study addresses the optimized design of falling-film heat exchanger tubes, aiming to enhance heat transfer efficiency and reduce thermal losses, thereby offering potential pathways for efficient green energy utilization. Ten tube models were established and analyzed using computational fluid dynamics (CFD) under constant heat flux conditions. The study investigated the effects of the position, number, and ellipticity (e) of external protrusions on the flow characteristics and heat transfer performance of oily wastewater. The simulation revealed that different protrusion configurations significantly influence hydrodynamic behavior and heat transfer mechanisms. It was found that introducing flow disturbances at an early developmental stage enhances the overall heat transfer performance of the external fluid. Specifically, for a tube with e = 0.5, the heat transfer coefficients (HTC) initially increases and then decreases with increasing Reynolds numbers (Re). This behavior is attributed to the reduction in flow stability caused by the protrusions at higher Re values, which promotes vortex shedding and leads to more complex flow patterns, thereby impairing heat transfer efficiency. Furthermore, as the number of protrusions increases, the overall HTC of the enhanced elliptical tube also follows a trend of an initial increase and then decrease. These results suggest the existence of an optimal protrusion density that enhances turbulence without incurring excessive resistance that would degrade thermal performance. Full article

(This article belongs to the Section Liquid–Fluid Coatings, Surfaces and Interfaces)

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1 pages, 124 KB

Open AccessCorrection

Correction: Florean et al. The Influence of TiO₂ Nanoparticles on the Physico–Mechanical and Structural Characteristics of Cementitious Materials. Coatings 2024, 14, 218

by Carmen T. Florean, Horatiu Vermesan, Gyorgy Thalmaier, Bogdan V. Neamtu, Timea Gabor, Cristina Campian, Andreea Hegyi and Alexandra Csapai

Coatings 2025, 15(11), 1339; https://doi.org/10.3390/coatings15111339 - 18 Nov 2025

Viewed by 253

Abstract

There was an error in the original publication [...] Full article

9 pages, 2279 KB

Open AccessArticle

Influence of Annealing Temperatures on Raman and Optical Absorption Spectra of TiO₂ Nanorod Thin Film Coatings

by Shangrong Chen and Hong Li

Coatings 2025, 15(11), 1338; https://doi.org/10.3390/coatings15111338 - 18 Nov 2025

Viewed by 257

Abstract

Titanium dioxide (TiO₂) is an important semiconductor material widely used in both fundamental studies and technological applications. Herein, TiO₂ nanorod thin film coatings were fabricated on transparent conductive fluorine-doped tin oxide (FTO) substrates using a hydrothermal synthesis approach, followed by [...] Read more.

Titanium dioxide (TiO₂) is an important semiconductor material widely used in both fundamental studies and technological applications. Herein, TiO₂ nanorod thin film coatings were fabricated on transparent conductive fluorine-doped tin oxide (FTO) substrates using a hydrothermal synthesis approach, followed by annealing at various temperatures. The effects of annealing temperatures on the Raman and optical absorption spectra were systematically investigated to elucidate the behavior of Raman-active lattice vibrations and optical transitions. As the annealing temperatures increased, both the full width at half maximum of the Raman vibrational modes and the band gap of the TiO₂ nanorod thin films decreased. These trends indicate enhanced crystallinity and phonon lifetimes at higher annealing temperatures. The longer phonon lifetimes contribute to reduced electron–hole recombination, while the narrower band gap extends the optical absorption range into the visible region. This study provides valuable insights into the relationship between annealing temperatures and the structural, vibrational and optical properties of rutile TiO₂ nanorod thin film coatings, highlighting their potential for improved performance in photoelectrocatalytic and optoelectronic applications. Full article

(This article belongs to the Section Thin Films)

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14 pages, 3799 KB

Open AccessArticle

Slurry Aluminizing of Nickel Electroless Coated Nickel-Based Superalloy

by Thomas Kepa, Gilles Bonnet, Giulia Pedrizzetti, Virgilio Genova, Giovanni Pulci, Cecilia Bartuli and Fernando Pedraza

Coatings 2025, 15(11), 1337; https://doi.org/10.3390/coatings15111337 - 17 Nov 2025

Viewed by 369

Abstract

Nickel-based superalloys require protective low-activity aluminide coatings to withstand high-temperature oxidation and corrosion in turbine applications. As opposed to conventional gas processes, this study investigates the mechanisms of formation of alternative low-activity nickel aluminide coatings on the René N5 superalloy through electroless nickel [...] Read more.

Nickel-based superalloys require protective low-activity aluminide coatings to withstand high-temperature oxidation and corrosion in turbine applications. As opposed to conventional gas processes, this study investigates the mechanisms of formation of alternative low-activity nickel aluminide coatings on the René N5 superalloy through electroless nickel pre-deposition followed by slurry aluminizing. Different thicknesses of electroless nickel layers (5, 10, 25 μm) were deposited and subsequently aluminized with varying slurry amounts (5–16 mg/cm²) under controlled heat treatments at 700–1080 °C with heating rates of 5 and 20 °C/min. Without electroless pre-deposition, high-activity coatings with refractory element precipitates formed. With electroless nickel, a precipitate-free low-activity coating developed, with thickness increasing linearly from 15 to 40 μm proportional to the initial electroless layer. An increasing slurry amount raised the overall coating thickness from 27 to 67 μm. Kirkendall porosity formed exclusively during the δ-Ni₂Al₃ to β-NiAl phase transformation at elevated temperature. Reducing the heating rate from 20 to 5 °C/min significantly decreased void formation by promoting more balanced Ni-Al interdiffusion. This work demonstrates that combining electroless nickel with slurry aluminizing provides an efficient route for producing low-activity coatings with controlled microstructure and minimal porosity. Full article

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

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20 pages, 6486 KB

Open AccessArticle

Evaluation of Particle Deposition Characteristics in Bent Tubes at Different Dimple Locations

by Zeyu Wang, Hao Lu and Zunshi Han

Coatings 2025, 15(11), 1336; https://doi.org/10.3390/coatings15111336 - 17 Nov 2025

Viewed by 313

Abstract

The deposition of particulate matter on rough pipe surfaces is critical in fields such as energy, chemical engineering, and air pollution control. This study employs a combined approach utilizing the Renormalized Group (RNG) k-ɛ model and the discrete phase model (DPM). [...] Read more.

The deposition of particulate matter on rough pipe surfaces is critical in fields such as energy, chemical engineering, and air pollution control. This study employs a combined approach utilizing the Renormalized Group (RNG) k-ɛ model and the discrete phase model (DPM). The particle deposition characteristics in circular bent pipe channels with different dimple positions were investigated. To improve simulation fidelity, a model for particle-wall rebound was developed using user-defined function (UDF). The results indicate that the dimple structure influences the deposition location of particles. Particle deposition is minimal on the lower surface and leeward side of the dimple structure. For operating conditions where St ≤ 0.27, θ = 15° yields the optimal effect on enhancing the particle deposition rate, achieving a maximum increase of 18.2%. For conditions where St ≥ 0.461, the optimal angle is θ = 30°, resulting in a maximum deposition rate increase of 14.126%. The deposition rate of dimple structures varies depending on their installation location. In this study, the deposition rate was lowest at θ = 65°. The dimple structure can serve as a sacrificial element, providing protection for the rest of the bent pipe. In the future, channels incorporating this structure can be applied to removal or air purification equipment. Full article

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9 pages, 7115 KB

Open AccessArticle

Surface Evolution and Performance of 45CrNiMoV Steel Modified by Electron Beam Irradiation

by Huihui Wang, Fuquan Long, Zhisen Liang, Shangfeng Cai, Rujin Lv and Shengzhi Hao

Coatings 2025, 15(11), 1335; https://doi.org/10.3390/coatings15111335 - 16 Nov 2025

Viewed by 341

Abstract

Enhancing the surface mechanical properties and extending the service life of 45CrNiMoV mold steel are critical goals in mold development. To achieve these objectives, electron beam (EB) irradiation was employed to treat the 45CrNiMoV mold steel. This high-energy physical process enables precise modification [...] Read more.

Enhancing the surface mechanical properties and extending the service life of 45CrNiMoV mold steel are critical goals in mold development. To achieve these objectives, electron beam (EB) irradiation was employed to treat the 45CrNiMoV mold steel. This high-energy physical process enables precise modification of the surface microstructure. By meticulously controlling EB parameters, including energy, dose, and scanning mode, significant structural alterations occur in the surface layer. Consequently, the surface microhardness more than doubles, reaching 812.7 HV. This enhancement is attributed to grain refinement, increased dislocation density, and potential formation of new phases induced by EB irradiation. Beyond hardness improvement, the wear resistance of the treated specimen increases by 2.5-fold. Under standardized testing conditions, wear loss decreases markedly from 0.28 mg to 0.11 mg. This reduction in wear loss not only extends the mold’s operational lifespan but also minimizes maintenance and replacement requirements, thereby reducing production downtime and associated costs. This study transcends mere presentation of experimental data by comprehensively elucidating the intricate relationship between surface microstructure and the overall mechanical properties of 45CrNiMoV mold steel. Advanced characterization techniques, including scanning electron microscopy (SEM) and X-ray diffraction (XRD), were utilized to uncover the underlying mechanisms. The refined microstructure, characterized by fine grains and elevated dislocation density, impedes dislocation movement and crack propagation, thereby enhancing both hardness and wear resistance. Full article

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

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20 pages, 962 KB

Open AccessArticle

Effect of Hygiene and Nano-Color Pigment Modification on Hardness, Glossiness, and Adhesion Strength of Some Surface Coating Materials

by Recep Aykan and Hacı İsmail Kesik

Coatings 2025, 15(11), 1334; https://doi.org/10.3390/coatings15111334 - 16 Nov 2025

Viewed by 288

Abstract

The aim of this study was to determine the effects of hygiene (H) and nano-color pigment (NCP) modifications on hardness, glossiness, and adhesion strength of some surface coating materials produced specifically for use in wooden toys. For this purpose, H- and NCP-modified polyurethane [...] Read more.

The aim of this study was to determine the effects of hygiene (H) and nano-color pigment (NCP) modifications on hardness, glossiness, and adhesion strength of some surface coating materials produced specifically for use in wooden toys. For this purpose, H- and NCP-modified polyurethane (PU) and waterborne (WBV) varnishes were applied to specimens prepared from Oriental beech (Fagus orientalis L.) and Oriental plane (Platanus orientalis L.) woods; Oriental beech, birch (Betula pendula), and poplar (Populus deltoides) plywood; and medium-density fiberboard (MDF). Then, hardness, glossiness, and adhesion values were determined. Results indicated that the highest values were obtained for hardness in PU and PU*NCP applied to MDF; for glossiness in WBV*H applied to birch plywood and MDF; and for adhesion strength in WBV and PU*H applied to beech. H and NCP modifications have significant effects on hardness, glossiness, and adhesion strength. As a result, it was determined that hardness and glossiness increased with H modification and decreased with NCP, especially glossiness. Furthermore, it was determined that H and NCP decreased the adhesion strength. Future studies comparing natural antibacterial effects of different wood species with various coating types will contribute to the development of products that are safe for children and sustainable. Full article

(This article belongs to the Special Issue Treatments and Modifications for Wood Surface Protection and Wood Bonding)

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14 pages, 1015 KB

Open AccessArticle

Gellan Gum-Based Edible Coatings Enriched with Scenedesmus spp. Extract to Enhance the Postharvest Quality and Shelf Life of Mangoes

by Rafael González-Cuello, Joaquín Hernández-Fernández and Rodrigo Ortega-Toro

Coatings 2025, 15(11), 1333; https://doi.org/10.3390/coatings15111333 - 16 Nov 2025

Viewed by 297

Abstract

Mango (Mangifera indica L.) is one of the most important tropical fruits; however, its limited postharvest shelf life restricts its commercial distribution. This study aimed to assess the influence of edible coatings formulated with high-acyl gellan gum (HAG), low-acyl gellan gum (LAG), [...] Read more.

Mango (Mangifera indica L.) is one of the most important tropical fruits; however, its limited postharvest shelf life restricts its commercial distribution. This study aimed to assess the influence of edible coatings formulated with high-acyl gellan gum (HAG), low-acyl gellan gum (LAG), and their blends enriched with an aqueous extract of Scenedesmus spp. on the preservation of mango quality during postharvest storage. The film-forming solutions based on HAG, LAG, and their combination (HAG/LAG) were enriched with Scenedesmus spp. extract at two concentrations (1 and 2% w/v) and subsequently employed for coating whole mango fruits. The coated samples were analyzed throughout storage to assess their physicochemical and physiological quality attributes, including weight loss, soluble solids content, titratable acidity, color variation, malondialdehyde accumulation, antioxidant activity, respiration rate, ethylene production, and hydrogen peroxide content. The results showed that coated fruits exhibited reduced color changes, lower weight loss, and improved visual acceptability compared to controls. Coatings containing 2% Scenedesmus spp., particularly HAG-based formulations, significantly decreased malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) accumulation, enhanced antioxidant capacity, and stabilized respiration rate and ethylene production, delaying ripening and senescence. These effects were associated with the oxygen barrier properties of gellan gum and the antioxidant compounds present in Scenedesmus spp. Overall, the findings highlight that HAG coatings enriched with Scenedesmus spp. represent a sustainable and efficient approach to extend shelf life and preserve the physicochemical and nutritional attributes of mangoes. Full article

(This article belongs to the Special Issue Advances in Food Technology: Bioactive Films and Coatings for Food Packaging)

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14 pages, 2318 KB

Open AccessArticle

Synergistic Effects of MXene and Carbon Nanotubes in Multi-Stimuli-Responsive Chitosan Materials: Combining Shape Memory and Electromagnetic Shielding Functions

by Ziyun Li, Shuai Yang, Sitong Wang, Jiaying Liu, Ning Guo, Zhichao He, Zijian Song and Yingchun Li

Coatings 2025, 15(11), 1332; https://doi.org/10.3390/coatings15111332 - 15 Nov 2025

Viewed by 414

Abstract

Shape memory polymers (SMPs) are a class of smart materials that exhibit unique shape-fixing and recovery abilities, attracting wide attention for applications in electronics, aerospace, and biomedical engineering. Chitosan (CS) as a renewable biopolymer, possessing good biocompatibility, biodegradability, and antimicrobial properties; its use [...] Read more.

Shape memory polymers (SMPs) are a class of smart materials that exhibit unique shape-fixing and recovery abilities, attracting wide attention for applications in electronics, aerospace, and biomedical engineering. Chitosan (CS) as a renewable biopolymer, possessing good biocompatibility, biodegradability, and antimicrobial properties; its use as a matrix enhances the environmental compatibility and bio-adaptability of SMPs. MXene, as a novel two-dimensional material, is characterized by high electrical conductivity, abundant surface functional groups and good hydrophilicity, showing potential in energy storage, electromagnetic shielding and sensing. In this work, CS and poly (vinyl alcohol) (PVA) were used as the polymer matrix, and carbon nanotubes (CNTs) together with MXene were introduced as co-fillers to construct multifunctional composites. The effect of the CNTs/MXene hybrid fillers on mechanical properties, electromagnetic shielding and multi-stimuli-responsive shape memory behavior was systematically investigated. After ratio optimization, the composites showed excellent comprehensive performance: tensile strength reached up to 20.0 MPa, Young’s modulus up to 292.2 MPa, and maximum elongation at break of 23.2%; electromagnetic interference shielding effectiveness (SE_T) in the X-band (8.2–12.4 GHz) reached a maximum of 10.6 dB; shape fixation rates exceeded 90%; under thermal stimulation, a shape recovery ratio of 98.3% was achieved within 41.7 s; light-driven recovery rate reached 86.5% with a minimal recovery time of 82.3 s; under electrical stimulation the highest recovery rate was 94.1% with a shortest recovery time of 30 s. This study successfully prepared functional multi-stimuli-responsive shape memory composite films and provided a new strategy for the design of green smart materials. Full article

(This article belongs to the Special Issue Multifunctional Polymer Thin Films for Surface Engineering)

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13 pages, 2511 KB

Open AccessArticle

Enhancing the Mechanical Robustness of Aerosol-Based Brittle Pt/C Electrodes Through Thermal Annealing

by Nathan Heo, Won-Yong Jeong, Ji Hun Kim and Jae-Bum Pyo

Coatings 2025, 15(11), 1331; https://doi.org/10.3390/coatings15111331 - 15 Nov 2025

Viewed by 361

Abstract

Nanoporous Pt/C electrodes fabricated via aerosol coating offer excellent reactant delivery and electrochemical activity owing to their high porosity. However, the practical application prospects of such electrodes are limited by their poor mechanical properties. Herein, we quantitatively analyze the effects of thermal annealing [...] Read more.

Nanoporous Pt/C electrodes fabricated via aerosol coating offer excellent reactant delivery and electrochemical activity owing to their high porosity. However, the practical application prospects of such electrodes are limited by their poor mechanical properties. Herein, we quantitatively analyze the effects of thermal annealing (at 110, 150, 190, and 230 °C) on the mechanical stability and electrical properties of aerosol-based Pt/C electrodes. Post-annealing at an optimal temperature of 190 °C improved the tensile strength by 65.3%, increased their elongation from 0.82% to 1.78%, and decreased the electrical resistance while maintaining the secondary pore structure. Analyses of the electrode’s surface roughness, pore structure, and contact angle indicate that thermal reconstruction of the ionomer is crucial for stabilizing the electrode structure and controlling its surface properties. Finite element simulations using experimentally measured single-electrode properties enabled accurate prediction of the mechanical behavior of the membrane electrode assembly. These results provide design guidelines for balancing the process efficiency with the mechanical stability of aerosol-based Pt/C electrodes and can be used to improve their application prospects in aerosol-based fuel cell catalyst layers. Full article

(This article belongs to the Special Issue Advanced Functional Nanostructured Films and Coatings for Energy Applications, 2nd Edition)

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33 pages, 10935 KB

Open AccessArticle

High-Energy Supercapacitor Constructed by Cerium-Doped Iron Tungstate Cathode Materials with Oxygen Vacancies and Hydrophilic Carbon Nanotube Anode

by Liyuan Shan and Lei Xiong

Coatings 2025, 15(11), 1330; https://doi.org/10.3390/coatings15111330 - 14 Nov 2025

Viewed by 404

Abstract

To address the worsening energy crisis from rapid fossil fuel consumption, this study synthesized Ce-FeWO₄ composites and hydrophilic carbon nanotubes. XRD and other characterizations showed all intermediates had rough, porous nanosheet morphology; Ce-doping formed disordered porous structure in FeWO₄, increasing [...] Read more.

To address the worsening energy crisis from rapid fossil fuel consumption, this study synthesized Ce-FeWO₄ composites and hydrophilic carbon nanotubes. XRD and other characterizations showed all intermediates had rough, porous nanosheet morphology; Ce-doping formed disordered porous structure in FeWO₄, increasing its specific surface area. Three-electrode tests confirmed optimal parameters: 0.5% Ce-doping and 12 h growth. Ce-FeWO₄ exhibited a specific capacity of 1875 ± 28 F/g at 1 A/g (based on five parallel samples), and retained 1807 F/g after 3000 cycles (exceeding previous studies) with excellent stability. The Ce-FeWO₄//CNTs asymmetric supercapacitor achieved 152 F/g specific capacity, 81.4 Wh/g energy density, and 768 W/kg power density. The simple, efficient, eco-friendly preparation process and the material’s high capacitance and stability offer broad application prospects in the electrode field. Full article

(This article belongs to the Special Issue High-Performance Dielectric Ceramic Films and Coatings for Energy Storage Capacitors)

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Coatings, Volume 15, Issue 11 (November 2025) – 127 articles

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