Coatings

47 pages, 3670 KB

Open AccessReview

Toxicological and Environmental Risk Assessment of Biopolymeric Coatings for Horticultural Produce: A Comprehensive Review on Biosafety, Degradation, and Ecological Risks

by Aldenora dos Santos Vasconcelos, Lorena Vieira Bentolila de Aguiar, Vítor Alves Pessoa, Iracimar Batista do Carmo, Larissa Batista do Nascimento Soares, Giovanna Lima-Silva, Daiane Barão Pereira, Patrick Cruz do Nascimento, Josilene Lima Serra Pereira, Ceci Sales-Campos, Larissa Ramos Chevreuil, Walter José Martínez-Burgos and Roberta Pozzan

Coatings 2026, 16(4), 452; https://doi.org/10.3390/coatings16040452 - 9 Apr 2026

Abstract

The increasing adoption of biopolymeric and nanostructured coatings for horticultural produce has emerged as a sustainable strategy to mitigate postharvest losses and extend shelf life. However, while their technological performance has been extensively documented, comprehensive and integrative assessments of biosafety, potential human health [...] Read more.

The increasing adoption of biopolymeric and nanostructured coatings for horticultural produce has emerged as a sustainable strategy to mitigate postharvest losses and extend shelf life. However, while their technological performance has been extensively documented, comprehensive and integrative assessments of biosafety, potential human health implications, and environmental risks profiles are still insufficiently explored. This review critically analyzes recent advances in polysaccharide, protein, and lipid-based coatings, including nanoenabled systems incorporating metallic nanoparticles and bioactive agents. The mechanisms underlying gas barrier properties, antimicrobial activity, and preservation efficacy are discussed alongside degradation pathways in composting, soil, and aquatic environments. Particular attention is given to nanoparticle release, migration potential, gastrointestinal fate, and toxicological endpoints such as oxidative stress, genotoxicity, endocrine disruption, and immunomodulation. Ecotoxicological evidence across trophic levels, from microorganisms and invertebrates to fish and amphibians, is examined, highlighting sublethal and mechanistic biomarkers relevant to environmental risk assessment. Regulatory frameworks from major agencies are also compared to contextualize current safety standards and limitations. Overall, although biopolymeric coatings represent promising alternatives to conventional plastics, their life-cycle impacts, transformation products, and nano-related uncertainties require comprehensive, multilevel risk evaluation to ensure truly sustainable and safe postharvest applications. Full article

(This article belongs to the Special Issue Innovative Coating Technologies for Preservation and Safety of Horticultural Produce)

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26 pages, 6283 KB

Open AccessArticle

Surface Defect Detection in Liquid Crystal Display Polariser Coating Manufacturing Based on an Enhanced YOLOv10-N Approach

by Jiayue Zhang, Shanhui Liu, Minghui Chen, Kezhan Zhang, Yinfeng Li, Ming Peng and Yeting Teng

Coatings 2026, 16(4), 451; https://doi.org/10.3390/coatings16040451 - 8 Apr 2026

Abstract

To address the issues of uneven grayscale distribution, weak defect features, and small target scales on the coating surface of LCD polarizers during manufacturing, an improved YOLOv10-N-based method is proposed for surface defect detection. First, a polarizer coating defect dataset is constructed based [...] Read more.

To address the issues of uneven grayscale distribution, weak defect features, and small target scales on the coating surface of LCD polarizers during manufacturing, an improved YOLOv10-N-based method is proposed for surface defect detection. First, a polarizer coating defect dataset is constructed based on the LCD polarizer coating process and the characteristics of coating defects. Adaptive median filtering is then employed for image denoising, while a particle-swarm-optimization-based improved histogram equalization method is adopted for image enhancement. Next, the Scale-aware Pyramid Pooling (SCPP) module is introduced into the C2f module of the backbone network to construct the C2f_SCPP feature extraction module, thereby improving the model’s ability to detect coating defects with different morphologies through multi-scale semantic feature fusion. In addition, rotation-equivariant convolution PreCM is incorporated into the SPPF module of the backbone network to build the SPPF_PreCM module, which effectively suppresses feature redundancy and scale conflicts while strengthening the representation of tiny defects. Finally, while retaining the original Distribution Focal Loss (DFL) branch of YOLOv10, WIoU is used to replace CIoU as the IoU loss term in bounding box regression, thereby improving localization accuracy and accelerating model convergence during training. Experimental results show that, compared with YOLOv10-N, the proposed method improves mAP@0.5 and mAP@0.5:0.95 by 1.8 and 2.8 percentage points, respectively, demonstrating its effectiveness for polarizer coating defect detection. However, its generalization capability under diverse production environments, varying illumination conditions, and complex noise scenarios still requires further investigation. Full article

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

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23 pages, 3026 KB

Open AccessArticle

3D NiMnCo Electrocatalysts with Cauliflower Curd-Shaped Microspherical Morphology for an Efficient and Sustainable HER in Alkaline Freshwater/Seawater Media

by Sukomol Barua, Aldona Balčiūnaitė, Daina Upskuvienė, Jūrate Vaičiūnienė, Loreta Tamašauskaitė-Tamašiūnaitė and Eugenijus Norkus

Coatings 2026, 16(4), 450; https://doi.org/10.3390/coatings16040450 - 8 Apr 2026

Abstract

Electrocatalytic seawater splitting is an ideal strategy for the large-scale production of green hydrogen. Compared to scarce freshwater, oceanic seawater electrolysis represents a game-changer for the hydrogen economy. Herein, we report a cost-effective one-step synthesis of binder-free, self-supported 3D nickel–manganese–cobalt (NiMnCo) coatings on [...] Read more.

Electrocatalytic seawater splitting is an ideal strategy for the large-scale production of green hydrogen. Compared to scarce freshwater, oceanic seawater electrolysis represents a game-changer for the hydrogen economy. Herein, we report a cost-effective one-step synthesis of binder-free, self-supported 3D nickel–manganese–cobalt (NiMnCo) coatings on titanium (Ti) substrates and evaluated their electrocatalytic performance for the hydrogen evolution reactions (HERs) in alkaline media (1.0 M KOH), simulated seawater (SSW, 1.0 M KOH + 0.5 M NaCl) and alkaline natural seawater (ASW, 1.0 M KOH + natural seawater). These ternary coatings were electrodeposited on Ti substrates using an electrochemical deposition method via a dynamic hydrogen bubble template (DHBT) technique. The optimized ternary NiMnCo/Ti-2 electrocatalyst exhibited an enhanced HER activity in both alkaline and seawater media, achieving an ultra-low overpotential of 29, 59 and 66 mV to reach the benchmark current density of 10 mA cm⁻² in SSW, ASW and 1.0 M KOH, respectively. This efficient 3D ternary NiMnCo/Ti-2 electrocatalyst demonstrated stable long-term performance at a constant potential of −0.23 V (vs. RHE) and a constant current density of 10 mA cm⁻² for 50 h without any significant degradation. Furthermore, it exhibited long-term stability in alkaline electrolyte and simulated seawater during multi-step chronopotentiometric testing at variable current densities from 20 mA cm⁻² to 100 mA cm⁻² for 18 h. This superior performance can be attributed to its unique intermetallic structure and multi-component composition, which provides good Cl⁻ resistance, electrochemical stability and synergistic effects among its constituents. Therefore, the optimized NiMnCo/Ti-2 electrocatalyst is a promising candidate for practical seawater electrolysis aiming at green hydrogen production. Full article

(This article belongs to the Special Issue Advanced Coatings for Enhanced Electrochemical Catalysis and Energy Storage Technologies)

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14 pages, 981 KB

Open AccessArticle

Modeling and Computational Analysis of Failure Mechanism of Photocatalytic Anti-Corrosion Materials Driven by Multi-Source Environmental Data

by Yanwei Tong, Hui Xu and Shuyuan Jia

Coatings 2026, 16(4), 449; https://doi.org/10.3390/coatings16040449 - 8 Apr 2026

Abstract

Photocatalytic anti-corrosion materials are an emerging intelligent protective material that has been widely used in marine and offshore engineering in recent years. However, its failure mechanism under multi-factor coupling is complex, and it is difficult for traditional methods to achieve accurate life prediction [...] Read more.

Photocatalytic anti-corrosion materials are an emerging intelligent protective material that has been widely used in marine and offshore engineering in recent years. However, its failure mechanism under multi-factor coupling is complex, and it is difficult for traditional methods to achieve accurate life prediction and mechanism analysis. This article takes submarine pipelines as the research object and designs an innovative multi-source environmental data-driven method combined with deep learning (DL), aiming to establish an intelligent prediction model for the failure of the material. This article first systematically collects the multi-source heterogeneous data of materials during service; on this basis, this article constructs a hybrid DL model. Firstly, a multi-scale multimodal image feature fusion network (MMFCT) based on the combination of convolutional neural network (CNN) and Transformer is adopted to automatically extract corrosion features from microscopic images and capture the dynamic correlation between environmental temporal data and performance degradation; then, the Sparrow Search Algorithm (SSA) was constructed to optimize the BP neural network (BPNN) model for predicting the ultimate bearing capacity of submarine corroded pipelines. Simulation experiments show that the proposed method achieves accurate prediction of material remaining life and key performance degradation paths. The corrosion recognition precision reaches 94.7%, and the bearing capacity prediction error remains below 3.1%. Full article

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

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19 pages, 3111 KB

Open AccessReview

A Review of Carbonation of C-S-H: From Atomic Structure to Macroscopic Behavior

by Yi Zhao and Junjie Wang

Coatings 2026, 16(4), 448; https://doi.org/10.3390/coatings16040448 - 8 Apr 2026

Abstract

Calcium–silicate–hydrate (C-S-H), the primary binding phase governing cement paste cohesion, undergoes progressive physicochemical transformation upon carbonation—a process that critically dictates concrete durability in atmospheric environments. When CO₂ penetrates the porous cement matrix, it triggers a cascade of degradation mechanisms: calcium leaching decalcifies [...] Read more.

Calcium–silicate–hydrate (C-S-H), the primary binding phase governing cement paste cohesion, undergoes progressive physicochemical transformation upon carbonation—a process that critically dictates concrete durability in atmospheric environments. When CO₂ penetrates the porous cement matrix, it triggers a cascade of degradation mechanisms: calcium leaching decalcifies the C-S-H structure, inducing polymerization of silicate chains from dimeric to longer-chain configurations, while concurrent precipitation of calcium carbonate and amorphous silica gel fundamentally reconstitutes the nanoscale architecture. These nanoscale alterations propagate to macroscopic property evolution, manifesting as initial strength and stiffness gains due to pore-filling carbonation products followed by eventual deterioration as the cohesive binding network deteriorates. This review synthesizes current understanding of carbonation-induced structural evolution, examining the coupled influences of environmental parameters—CO₂ concentration, relative humidity, and temperature—alongside C-S-H intrinsic chemistry (Ca/Si ratio, aluminum substitution, and alkali content) on reaction kinetics and material performance. However, significant knowledge gaps persist: predictive models for in-service carbonation rates remain elusive due to the disconnect between idealized laboratory conditions and the heterogeneous, cracked reality of field concrete; the causal linkage between nanoscale C-S-H alteration and macroscale cracking patterns along with physical performance is poorly resolved, and most mechanistic studies rely on synthetic C-S-H, neglecting the compositional complexity of real Portland cement systems. We further propose emerging protection strategies, including surface barrier coatings and low-carbon alternative binders (geopolymers, calcium sulfoaluminate cements, carbon-negative materials such as recycled cement), which demonstrate enhanced carbonation resistance. Future research priorities include developing effective coating barriers for carbonation protection, developing operando characterization techniques for real-time reaction monitoring, deploying machine learning algorithms to bridge atomistic simulations with structural-scale predictions, and establishing long-term field performance databases to validate laboratory-derived degradation models. Full article

(This article belongs to the Special Issue Advanced Coating Barriers for the Protection of Reinforced Concrete and Pavement, 3rd Edition)

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19 pages, 3874 KB

Open AccessArticle

Real-Time pH Monitoring in Microreactor Channels Using Sol–Gel Thin-Film Coatings

by Elizabeta Forjan, Marijan-Pere Marković and Domagoj Vrsaljko

Coatings 2026, 16(4), 447; https://doi.org/10.3390/coatings16040447 - 8 Apr 2026

Abstract

Sol–gel-based optical functional sensor coatings were developed for real-time monitoring of multiphase saponification reactions in microreactors. Various pH-sensitive indicator mixtures, including bromocresol green and bromocresol purple (BCG and BCP) and methyl red–methyl orange, were incorporated into sol–gel coatings and evaluated on test plates [...] Read more.

Sol–gel-based optical functional sensor coatings were developed for real-time monitoring of multiphase saponification reactions in microreactors. Various pH-sensitive indicator mixtures, including bromocresol green and bromocresol purple (BCG and BCP) and methyl red–methyl orange, were incorporated into sol–gel coatings and evaluated on test plates across pH range of 2–12. Coatings with BCG and BCP 1:3 demonstrated the most pronounced color change at high pH (11–12), with distinct hue (H) transitions providing a reliable measure of local pH. These optimized coatings were integrated into microreactor channels to track the passage of oil and NaOH slugs under varying flow rates. Hue analysis produced reproducible plateaus corresponding to NaOH-rich (H = 50°) and oil-rich (H = 41°) phases, enabling droplet-level resolution of slug flow and detection of flow-regime transitions. The sensor response was fully reversible, highlighting the robustness and reusability of the coatings. Unlike previous high-resolution fluorescence-based systems, this approach relies on simple visible-light imaging and low-cost data extraction, leaving the reaction chemistry unaltered. The results demonstrate that sol–gel coatings coupled with hue-based analysis provide a practical, noninvasive, and real-time monitoring strategy for multiphase reactions in microreactors, with potential for implementation in industrial or IoT-enabled process control systems. Full article

(This article belongs to the Special Issue Advances in 3D Printing for Functional Coatings and Materials)

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23 pages, 6242 KB

Open AccessArticle

Microstructure and Mechanical Properties of Narrow-Gap Laser Wire-Fed Welded S32101 Duplex Stainless Steel Thick-Plate Joints

by Yuetong Liu, Jinjie Wang, Juan Fu and Feiyun Wang

Coatings 2026, 16(4), 446; https://doi.org/10.3390/coatings16040446 - 7 Apr 2026

Abstract

Duplex stainless steel is widely used in nuclear power, the chemical industry, coastal infrastructure, and other fields due to its excellent mechanical properties, physical properties, and corrosion resistance. This paper focuses on the narrow-gap groove laser welding with wire filling conducted on 25 [...] Read more.

Duplex stainless steel is widely used in nuclear power, the chemical industry, coastal infrastructure, and other fields due to its excellent mechanical properties, physical properties, and corrosion resistance. This paper focuses on the narrow-gap groove laser welding with wire filling conducted on 25 mm S32101 duplex stainless steel. It analyzes the microstructural features of various regions within the welded joint and evaluates its mechanical properties and corrosion resistance. Research indicates that the thermal cycle effect during multi-layer and multi-pass welding significantly affects the microstructure and properties of the joint. Austenite in the weld seam area mainly precipitates along the dendrite boundaries; in the overlap area of the weld beads, due to the secondary thermal cycle effect, the austenite content significantly increases to 56.2%, and the grain size is refined; in the heat-affected zone (HAZ) near the seam, austenite appears in stripes, and its content decreases to 39.4%. Mechanical property tests reveal that the welded joint exhibits an average tensile strength of 705 MPa, surpassing that of the base material. The corrosion resistance of the weld zone closely mirrors that of the base material, yet the corrosion resistance of the heat-affected zone (HAZ) is diminished due to the reduction in austenite content and the potential precipitation of harmful phases. Full article

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

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15 pages, 16359 KB

Open AccessArticle

Two-Dimensional rGO-Supported Mo₂S₃ Catalysts with Tunable Electronic Structure for Efficient Electrochemical Water Splitting

by Mrunal Bhosale, Aditya A. Patil and Chan-Wook Jeon

Coatings 2026, 16(4), 445; https://doi.org/10.3390/coatings16040445 - 7 Apr 2026

Abstract

The rational design of cost-effective and highly active electrocatalysts for overall water splitting remains a critical challenge for sustainable hydrogen production. Herein, we report a two-dimensional reduced graphene oxide (rGO)-supported Mo₂S₃ nanohybrid catalyst with a tunable electronic structure engineered through [...] Read more.

The rational design of cost-effective and highly active electrocatalysts for overall water splitting remains a critical challenge for sustainable hydrogen production. Herein, we report a two-dimensional reduced graphene oxide (rGO)-supported Mo₂S₃ nanohybrid catalyst with a tunable electronic structure engineered through interfacial coupling. The intimate integration of Mo₂S₃ nanoflakes with conductive rGO nanosheet facilitates rapid electron transport, enhanced active site exposure, and optimized adsorption energetics for reaction intermediates. Structural and spectroscopic analyses confirm strong electronic interaction between Mo₂S₃ and rGO, leading to modulated charge density distribution and improved intrinsic catalytic activity. Electrochemical evaluations reveal significantly reduced overpotentials for oxygen evolution reaction (OER) with 166 mV overpotential at 10 mA cm⁻² current density, along with favorable Tafel kinetics with 38.1 mV dec⁻¹ and long-term operational stability in alkaline electrolyte. The rGO-Mo₂S₃-2||Pt-C cell delivers 10 mA cm⁻² at 1.64 V, indicating efficient alkaline water splitting. The enhanced performance is attributed to synergistic effects arising from electronic modulation, enhanced active sites, and accelerated interfacial charge transfer. Full article

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19 pages, 6753 KB

Open AccessArticle

Influence of a CaNa₂(EDTA) Additive on Plasma Electrolytic Oxidation of Zirlo Alloy and the Properties of the Resulting Coatings

by Wei Li, Guohua Yan, Qianna Zhang and Yingliang Cheng

Coatings 2026, 16(4), 444; https://doi.org/10.3390/coatings16040444 - 7 Apr 2026

Abstract

The plasma electrolytic oxidation (PEO) of Zirlo alloy was carried out in a phosphate electrolyte with CaNa₂(EDTA) as an additive (0–15 g/L) to improve its corrosion and wear resistance. The PEO behavior, microstructure, phase composition, and performance of coatings were characterized [...] Read more.

The plasma electrolytic oxidation (PEO) of Zirlo alloy was carried out in a phosphate electrolyte with CaNa₂(EDTA) as an additive (0–15 g/L) to improve its corrosion and wear resistance. The PEO behavior, microstructure, phase composition, and performance of coatings were characterized as a function of the concentration of the additive. The results indicate that the addition of CaNa₂(EDTA) promotes coating growth and improves the coating structure and phase composition. When the additive concentration is 5–10 g/L, the coating shows an improved thickness, and denser microstructure. The coatings consist of m-ZrO₂ and t-ZrO₂ as the main crystalline phases, as well as amorphous materials with Ca and P. The t-ZrO₂ phase content rises sharply when CaNa₂(EDTA) is added into the electrolyte (81.3% t-ZrO₂ is obtained under the condition with 10 g/L CaNa₂(EDTA)). Potentiodynamic polarization tests demonstrate that PEO treatment significantly enhances the corrosion resistance of Zirlo alloy. Under the condition of 5 g/L CaNa₂(EDTA), the corrosion current density of the coating decreases by two orders of magnitude compared to the substrate, achieving the best corrosion resistance. Friction and wear tests also show that the coating obtained at 5 g/L CaNa₂(EDTA) exhibits the shallowest wear scar and the lowest wear rate, demonstrating optimal wear resistance. This study shows the novelty of obtaining high-quality PEO coatings on Zirlo alloy based on Ca and P incorporation. Full article

(This article belongs to the Special Issue Plasma Electrolytic Oxidation (PEO) Coatings—3rd Edition)

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4 pages, 151 KB

Open AccessEditorial

Surface Modification for Improving the Performance of Engineering Components

by Annalisa Fortini and Mattia Merlin

Coatings 2026, 16(4), 443; https://doi.org/10.3390/coatings16040443 - 7 Apr 2026

Abstract

In the manufacturing industry, mechanical and structural elements are essential and are often located in harsh operational environments where they must withstand the synergic effects of wear, corrosion, fatigue, and elevated temperatures [...] Full article

(This article belongs to the Special Issue Surface Modification for Improving the Performance of Engineering Components)

17 pages, 6962 KB

Open AccessArticle

Effect of Ta on Microstructure, Mechanical Properties, and Soft Magnetic Performance of Fe-Based Amorphous Coatings Prepared by High-Speed Laser Cladding

by Haibo Huang, Xiaoqiang Yao, Jiangtong Yu, Yong Huang, Jintao Li and Xiaoqiang Wang

Coatings 2026, 16(4), 442; https://doi.org/10.3390/coatings16040442 - 7 Apr 2026

Abstract

High-speed laser cladding (HLC) technology can provide high cooling rates and low dilution rates for the preparation of metastable Fe-based amorphous phases. In this work, the effects of Ta content on the microstructure, mechanical properties, and soft magnetic performance of Fe-based amorphous alloys [...] Read more.

High-speed laser cladding (HLC) technology can provide high cooling rates and low dilution rates for the preparation of metastable Fe-based amorphous phases. In this work, the effects of Ta content on the microstructure, mechanical properties, and soft magnetic performance of Fe-based amorphous alloys were systematically investigated. The results indicated that Ta remained uniformly dispersed within the FeSiB amorphous powder, and no new phases were formed after mechanical ball milling. The higher mixing enthalpy of Ta and its atomic radius difference from other elements (such as Fe, Si, B) were beneficial in improving glass-forming ability (GFA), and with an increase in Ta element content from 0% to 2%, 4% and 6%, the amorphous phase content was 48.6%, 51.5%, 60.4% and 54.8%, respectively. The average microhardness of the coating with a Ta content of 4% was 1310 HV_0.2, which was 50HV_0.2 higher than before; in addition, the wear rate reduced from 2.21 × 10⁻⁴ mg·N⁻¹·m⁻¹ to 2.06 × 10⁻⁴ mg·N⁻¹·m⁻¹. Also, corrosion tests showed that the coating with a Ta content of 4% displayed superior corrosion resistance compared to that before the Ta addition. However, because the element Ta could alter the local electronic environment and enhance the local magnetic anisotropy of FeSiB, the saturation magnetic flux density (Ms) decreased from 1.64 T to 1.56 T, and the coercivity (Hc) increased from 0.9 A/m to 1.3 A/m, which caused degradation of the soft magnetic properties. Full article

(This article belongs to the Special Issue Laser Coatings and Surface Engineering)

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13 pages, 3902 KB

Open AccessArticle

Acceptor-Enriched Charge-Transfer Engineering for Long-Life and High-Rate Organic Cathodes in Aqueous Proton Batteries

by Xirui Song, Xinglin Yang, Jinlong Yang, Weichao Zhang and Peixiang Shi

Coatings 2026, 16(4), 441; https://doi.org/10.3390/coatings16040441 - 6 Apr 2026

Abstract

Aqueous proton batteries (APBs) are promising for safe energy storage, yet their cathode development is hindered by the lack of organic materials with reversible redox activity and long cycling stability in acidic media. Herein, an acceptor-enriched PNZ–TCNQ organic charge-transfer complex was constructed by [...] Read more.

Aqueous proton batteries (APBs) are promising for safe energy storage, yet their cathode development is hindered by the lack of organic materials with reversible redox activity and long cycling stability in acidic media. Herein, an acceptor-enriched PNZ–TCNQ organic charge-transfer complex was constructed by increasing the TCNQ ratio. Spectroscopic results are consistent with strengthened donor–acceptor interactions and altered local electronic environments. The PNZ–TCNQ cathode delivered ~190 mAh g⁻¹ at 0.6 A g⁻¹ and retained ~85% capacity after 10,000 cycles at 5 A g⁻¹ in acidic three-electrode tests. Kinetic analyses revealed mixed charge storage contributions from pseudocapacitive and diffusion-influenced processes. In situ/ex situ characterizations confirmed reversible redox evolution of the donor–acceptor complex with preserved molecular backbones. This work shows that tuning intermolecular charge-transfer interactions is an effective strategy for improving the cycling stability of organic cathodes in acidic aqueous electrolytes. Full article

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

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13 pages, 1942 KB

Open AccessFeature PaperArticle

High-Resolution Investigation of the Interfaces in Cathodic Arc Evaporated TiN/CrAlN Multilayer Coatings

by Saeideh Naghdali, Helene Waldl, Maximilian Schiester, Markus Pohler, Christoph Czettl, Michael Tkadletz and Nina Schalk

Coatings 2026, 16(4), 438; https://doi.org/10.3390/coatings16040438 - 6 Apr 2026

Abstract

TiN/CrAlN multilayer coatings were synthesized by cathodic arc deposition using 2-fold substrate rotation and alternating targets. The effect of substrate rotation on the layer sequence, elemental fluctuations and interface quality was examined using high-resolution transmission electron microscopy and atom probe tomography. The layers [...] Read more.

TiN/CrAlN multilayer coatings were synthesized by cathodic arc deposition using 2-fold substrate rotation and alternating targets. The effect of substrate rotation on the layer sequence, elemental fluctuations and interface quality was examined using high-resolution transmission electron microscopy and atom probe tomography. The layers exhibited semi-coherent growth across the interfaces. Minor interface roughness and elemental intermixing limited to below 2 nm at the interface could be observed. Further, the formation of a Ti-enriched sublayer in the Cr_1−xAl_xN as a result of the 2-fold rotation was identified. Full article

(This article belongs to the Special Issue Recent Developments in Tribological and Mechanical Performance of Metallic Materials and Coatings)

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18 pages, 6112 KB

Open AccessArticle

Study on Permeability Performance of OGFC Steel Slag Skid-Resistant Wearing Course Based on Interconnected Void Characteristics

by Yanjun Liu, Dengyun Hou, Shuxin Zheng and Cheng Wan

Coatings 2026, 16(4), 440; https://doi.org/10.3390/coatings16040440 - 5 Apr 2026

Abstract

To investigate the effects of distribution characteristics of microscopic voids (including the connectivity degree, pore-throat morphology, and size) on the permeability performance of open-graded friction course (OGFC) asphalt mixtures with steel slag as the anti-skid wearing course, two-dimensional computed tomography (CT) images of [...] Read more.

To investigate the effects of distribution characteristics of microscopic voids (including the connectivity degree, pore-throat morphology, and size) on the permeability performance of open-graded friction course (OGFC) asphalt mixtures with steel slag as the anti-skid wearing course, two-dimensional computed tomography (CT) images of OGFC steel slag asphalt mixture specimens were first obtained via X-ray technology. The MATLAB R2022b-based image subtraction algorithm was then adopted to identify the interconnected voids inside the specimens to quantitatively characterize the morphological differences in interconnected voids in OGFC steel slag asphalt mixtures with different gradations. Furthermore, Finite Element simulation by ANSYS 2021 R1 was conducted to explore the influences of the diversion angle of interconnected voids on the water flow characteristics of OGFC steel slag asphalt mixtures, involving the variation laws of water flow velocity, water pressure and flow path in the diversion structure, thereby analyzing the resultant effects on the permeability performance of the mixtures. The results show that the combination of X-ray CT scanning and image processing technology enables more convenient, accurate and intuitive characterization of the internal void distribution characteristics of the mixtures. It was found that the pore-throat properties, including size, length, quantity and equivalent diameter, are the dominant factors restricting the permeability capacity of OGFC steel slag asphalt mixtures. As the diversion angle increases from 20° to 60°, the pressure gradient increases by up to 103.92%. After passing through the diversion section, the flow velocity increases by approximately four times. The streamline density at the channel axis is 4.2–4.5 times that near the channel wall. This study realizes the rapid extraction of void characteristics and the identification of key influencing factors on the permeability performance of OGFC steel slag asphalt mixtures, an achievement that cannot be attained by the previous macroscopic research on the permeability performance of such mixtures. Full article

(This article belongs to the Special Issue Asphalt Interface Engineering and Advanced Functional Coatings for Sustainable Pavements)

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16 pages, 5615 KB

Open AccessArticle

Sequential Aging Tests of Cyclic Bending for the Reliability Assessment of Laminated Oxide/Silver/Oxide Flexible Transparent Conductors

by Jung-Yen Chang, Yu-Han Kao, Hung-Shuo Chang and Chiao-Chi Lin

Coatings 2026, 16(4), 439; https://doi.org/10.3390/coatings16040439 - 5 Apr 2026

Abstract

Flexible transparent conductors (FTCs) are key materials that determine the scalability and performance of flexible optoelectronic devices. This study explores the reliability of FTCs with laminated multilayer structures, specifically oxide/metal/oxide (OMO) films, through sequential testing composed of accelerated weathering and cyclic bending. Commercially [...] Read more.

Flexible transparent conductors (FTCs) are key materials that determine the scalability and performance of flexible optoelectronic devices. This study explores the reliability of FTCs with laminated multilayer structures, specifically oxide/metal/oxide (OMO) films, through sequential testing composed of accelerated weathering and cyclic bending. Commercially available ZTO/Ag/ZTO-based FTCs were selected as a model system to study, and Weibull analysis was employed to assess their failure behaviors. Results illustrate that weathered aged samples exhibit significantly impaired bending lifespan compared to unaged samples due to substrate embrittlement. Hence, the surface cracking mechanism alters as the weathering time is prolonged. Not only the weathering time, but also the thickness of the conductive metal layer plays an important role in influencing the bending reliability behaviors of the OMO FTCs. A sequential aging test that combines two-step UV weathering and an interim manual bending demonstrates that surface cracks can induce the degradation of both optical and electrical properties. Intricately complex bending modes would accelerate the deterioration. This study highlights the critical and synergistic roles of weathering aging and cyclic bending on the reliability of OMO FTCs, offering insights for future design and durability assessments of flexible optoelectronic devices. Research results also provide fundamental information for establishing application-specific reliability testing protocols for FTCs. Full article

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

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25 pages, 6094 KB

Open AccessArticle

Crack Extension Characteristics of Continuously Reinforced Concrete and Asphalt Composite Pavements Under Thermo-Mechanical Coupling and Non-Uniform Tire Loading

by Xizhong Xu, Xiaomeng Zhang, Xiangpeng Yan, Jincheng Wei, Jiabo Hu and Wenjuan Wu

Coatings 2026, 16(4), 437; https://doi.org/10.3390/coatings16040437 - 4 Apr 2026

Abstract

This study investigates the fracture initiation and propagation mechanisms of continuously reinforced concrete–asphalt (CRC+AC) composite pavements under the synergistic effects of diurnal temperature fluctuations and non-uniform tire loading. A three-dimensional (3D) thermo-mechanical coupled finite element (FE) model was developed, with its underlying mechanical [...] Read more.

This study investigates the fracture initiation and propagation mechanisms of continuously reinforced concrete–asphalt (CRC+AC) composite pavements under the synergistic effects of diurnal temperature fluctuations and non-uniform tire loading. A three-dimensional (3D) thermo-mechanical coupled finite element (FE) model was developed, with its underlying mechanical framework validated through laboratory-scale model tests conducted at 20 °C. The experimental results, involving strain monitoring at varying depths, demonstrated a high degree of consistency with numerical predictions in terms of spatial strain distribution, thereby ensuring the model’s reliability in capturing interlayer load-transfer efficiency. Building upon this validated mechanical foundation, numerical simulations were extended to analyze the low-temperature fracture response. The numerical results indicate that the maximum longitudinal and transverse tensile stresses in the asphalt layer are concentrated at the pavement surface, whereas the maximum shear stress occurs at a depth of 2–3 cm near the leading and trailing edges of the wheel load. Under low-temperature gradients, the Mode I stress intensity factor (K_I) at the crack tip exhibits a distinct diurnal opening–closing–reopening pattern, peaking at approximately 220 kPa·m^1/2 during the early morning hours (05:00–06:00). Furthermore, numerical simulations reveal the significant sensitivity of shear-sliding to axle loads; specifically, the peak Mode II stress intensity factor (K_II) increases monotonically from 190 to 230 kPa·m^1/2 as the axle load rises from 10 t to 16 t. Under non-uniform contact pressure, longitudinal cracking is primarily characterized by a mixed Mode I and Mode II mechanism driven by coupled tensile and shear stresses, whereas transverse cracking is dominated by Mode II shear failure. These findings suggest that implementing targeted traffic restrictions for overloaded vehicles during identified high-risk time windows can significantly enhance the structural durability and service life of composite pavements in cold regions. Full article

(This article belongs to the Special Issue Advanced Coating Barriers for the Protection of Reinforced Concrete and Pavement, 3rd Edition)

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24 pages, 6050 KB

Open AccessArticle

Hysteresis Heat Generation in Polyurethane O-Rings: Thermo-Mechanical Coupling Mechanism and Its Quantified Effect on Reciprocating Sealing Performance

by Chang Yang, Wenbo Luo, Jing Liu, Jiawei Liu, Yu Tang and Zhichao Wang

Coatings 2026, 16(4), 436; https://doi.org/10.3390/coatings16040436 - 4 Apr 2026

Abstract

Polyurethane O-ring seals are vital for the service life and sealing reliability of hydraulic systems, yet internal hysteresis heat generation under reciprocating motion causes localized temperature rise, altering contact pressure distribution and impairing sealing performance. This study aimed to clarify the coupled effects [...] Read more.

Polyurethane O-ring seals are vital for the service life and sealing reliability of hydraulic systems, yet internal hysteresis heat generation under reciprocating motion causes localized temperature rise, altering contact pressure distribution and impairing sealing performance. This study aimed to clarify the coupled effects of reciprocating motion parameters on O-ring hysteresis heat generation and sealing performance. A unified hysteresis heat generation rate expression was derived by combining the time–temperature superposition principle with the Maier–Göritz model, and the heat source model was integrated into a thermo-mechanically coupled finite element analysis (FEA) framework, validated by matching simulated and experimental temperature rise histories. Under baseline conditions, hysteresis heating causes the O-ring’s peak contact pressure to decrease by approximately 0.4 MPa during the outward stroke. Parametric analysis revealed that elevated operating parameters increase contact pressure to maintain effective sealing, but simultaneously intensify hysteresis heating. Quantitatively, the maximum O-ring temperature was highly sensitive to operating conditions, reaching 63.6 °C at 8 MPa hydraulic pressure, 60.0 °C at a 90 Hz reciprocating frequency, and up to 81.5 °C for a friction coefficient of 0.2. Although the current framework is limited by the exclusion of interfacial frictional heating, it enables the reliable quantitative prediction of thermal loads. Ultimately, this study provides a robust method for assessing sealing safety margins and offers theoretical guidance for the structural optimization of hydraulic sealing systems. Full article

(This article belongs to the Special Issue Polymer Coatings and Polymer Composites: Testing and Modeling)

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18 pages, 1516 KB

Open AccessArticle

Fire Behavior and Thermal Performance of Nano-Clay-Modified EVA Encapsulation for Building-Integrated Photovoltaic Systems

by Haoming Yuan, Weishan Yang and Yixin Su

Coatings 2026, 16(4), 435; https://doi.org/10.3390/coatings16040435 - 3 Apr 2026

Abstract

The building-integrated photovoltaic (BIPV) system has advantages in construction and energy, but due to the use of flammable polymer packaging materials, it introduces complex fire safety-related challenges. Although polymer backboards are traditionally considered to be the main combustible components in photovoltaic modules, recent [...] Read more.

The building-integrated photovoltaic (BIPV) system has advantages in construction and energy, but due to the use of flammable polymer packaging materials, it introduces complex fire safety-related challenges. Although polymer backboards are traditionally considered to be the main combustible components in photovoltaic modules, recent studies have shown that ethylene–vinyl acetate (EVA) packaging materials play a key role in the development of fires. This study investigated the fire behavior, optical properties and system-level fire effects of montmorillonite (MMT) nano-clay-modified EVA packaging materials. Through the 50 kW/m² conical calorimeter test, optical transmittance measurement and the accelerated aging test, pure EVA and EVA containing 3% MMT were evaluated, and the measured fire parameters were further incorporated into the simplified BIPV cavity fire model. The results show that MMT modification reduces the peak heat release rate of EVA by about 30%, delays the ignition time, and increases the formation of carbides, while maintaining the optical transmittance of more than 88%. At the system level, the reduction in heat release leads to a decrease in the cavity temperature and delays the ignition of adjacent insulation materials. These findings establish a direct link between material-level fire behavior and the fire performance of BIPV systems, indicating that nano-clay-modified EVA is a feasible strategy that can improve the fire safety of BIPV systems integrated into the facade without compromising optical or durability requirements. Full article

(This article belongs to the Section Functional Polymer Coatings and Films)

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18 pages, 9791 KB

Open AccessArticle

The Influence of Zn on the Surface Tension and Wettability of the Al-10Si Alloy on IF Steel at 1023 K

by Xinyan Chen, Ya Liu, Changjun Wu and Xuping Su

Coatings 2026, 16(4), 434; https://doi.org/10.3390/coatings16040434 - 3 Apr 2026

Abstract

Objective: This work aims to reduce the surface tension of an aluminum–silicon alloy melt by adding different amounts of the Zn element, thus improving the coatability and coating quality of hot-dip aluminum plating on steel plates. Method: Wetting experiments were conducted at 1023 [...] Read more.

Objective: This work aims to reduce the surface tension of an aluminum–silicon alloy melt by adding different amounts of the Zn element, thus improving the coatability and coating quality of hot-dip aluminum plating on steel plates. Method: Wetting experiments were conducted at 1023 K using a modified sessile drop method. Conclusions: The addition of the Zn element can reduce the surface tension of the Al-Si alloy, thus decreasing the wettability of the Al-Si alloy. Zn vapor can break down the surface oxide film to expose the fresh melt. The wettability of the Al-10Si alloy on interstitial-free (IF) steel and surface tension were investigated using the modified sessile drop method at 1023 K. Axisymmetric Drop Shape Analysis software was utilized to calculate the contact angles of the Al-10Si-xZn/Al₂O₃ and Al-10Si-xZn/IF steel systems (x ranges from 0 wt.% to 5 wt.%). Moreover, the microtopography and microstructure of surfaces and cross-sections were analyzed by means of an energy-dispersive spectrometer and scanning electron microscope. The results indicated that the surface tension of the alloy melt gradually decreases with an increase in Zn content, ranging from 874 to 760 mN/m. The contact angle of the Al-10Si-xZn alloy melt on IF steel also progressively decreases with increasing Zn content, which is attributed to the lower surface tension of Zn. This study also discovered that the Zn element can disrupt the oxide film of the Al-10Si alloy, exposing the fresh melt and thereby reducing the surface tension of the alloy liquid, thus enhancing wettability. The addition of Zn might be capable of improving the hot-dip aluminizing coatability of steel plates and the quality of the coating. Full article

(This article belongs to the Special Issue Advances in Metal Composite Coatings and Films: Microstructure, Physicochemical and Mechanical Properties)

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