Coatings

26 pages, 11540 KB

Open AccessArticle

Experimental Study on the Optimal Mix Proportion of Steel Fiber-Reinforced Concrete in Cold Regions

by Li-Ming Wu, Feng Gao, Guang-Na Liu, Hu-Xin-Tong Huang, Zi-Jian Wang, Yue Wang and Wen-Jie Luo

Coatings 2026, 16(2), 269; https://doi.org/10.3390/coatings16020269 - 23 Feb 2026

Viewed by 295

Abstract

To determine the optimal mix proportion of steel fiber-reinforced concrete in cold regions, this study adopted a multi-factor orthogonal experimental design method. A series of mix proportion schemes was formulated based on different water-to-binder ratios, steel fiber volume fractions, and combinations of mineral [...] Read more.

To determine the optimal mix proportion of steel fiber-reinforced concrete in cold regions, this study adopted a multi-factor orthogonal experimental design method. A series of mix proportion schemes was formulated based on different water-to-binder ratios, steel fiber volume fractions, and combinations of mineral admixtures such as silica fume. Mechanical performance tests and freeze–thaw cycle tests were conducted to obtain the strength, deformation characteristics, and durability degradation patterns of specimens with different mix proportions before and after freeze–thaw exposure. Meanwhile, scanning electron microscopy (SEM) was employed to observe the microscopic surface morphology of specimens, both pre- and post-freeze–thaw cycles, and to analyze the damage evolution in pore structures and the fiber–matrix interfacial transition zone, thereby elucidating the microscopic mechanism of freeze–thaw damage. Ultimately, by comprehensively comparing the macro-mechanical properties, freeze–thaw durability, and microstructural characteristics, the experimental results of different groups were evaluated to identify the optimal mix proportion for steel fiber-reinforced concrete, which exhibits excellent mechanical performance and durability under freeze–thaw conditions. The results indicated that freeze–thaw cycles significantly reduced the mechanical properties of the concrete. The optimal mix proportion was achieved with a water-to-binder ratio of 0.4, a silica fume content of 10%, and a steel fiber volume fraction of 1.5%. This optimal mix proportion can provide a direct reference for the material design and application of steel fiber-reinforced concrete in engineering projects located in cold regions. Full article

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

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24 pages, 4484 KB

Open AccessFeature PaperArticle

Polycarboxylic Acid/Calcium Carbonate Nanopowder-Derived Chelates as Sustainable Cross-Linked Wood Coatings with Improved Thermal Properties

by Jovale Vincent Tongco and Armando Gabriel McDonald

Coatings 2026, 16(2), 268; https://doi.org/10.3390/coatings16020268 - 23 Feb 2026

Cited by 1 | Viewed by 469

Abstract

This study presents a sustainable strategy for improving the thermal properties of pine wood through the application of calcium carbonate nanopowder (CCNP) chelated with polycarboxylic acids (citric acid (CA) and tartaric acid (TA)) as coatings. The chelation reaction was confirmed by the detection [...] Read more.

This study presents a sustainable strategy for improving the thermal properties of pine wood through the application of calcium carbonate nanopowder (CCNP) chelated with polycarboxylic acids (citric acid (CA) and tartaric acid (TA)) as coatings. The chelation reaction was confirmed by the detection of carbon dioxide (CO₂) gas. CCNP was characterized using microscopy and particle size analysis. The formation of crystalline calcium citrate and calcium tartrate was verified using FTIR and Raman spectroscopies, and XRD analysis. Wood treatment was conducted using different volumetric ratios of CA and TA. The CA-TA-treated (coated) wood blocks achieved the highest mass gain after treatment of around 89%, while the pure TA treatment exhibited enhanced leaching resistance, maintaining around 69% mass gain after leaching test. TGA conducted under oxidative (air) conditions showed that the coatings promoted char formation and produced inorganic residues from 6.4% to 7.8%, with the control resulting in negligible residual mass. Flame retardancy tests showed that the chelated coatings effectively delayed combustion and inhibited heat transfer, with the TA treatment showing improved flame retardancy performance by limiting the surface temperature to ~200 °C after 60 s of exposure, as compared to >550 °C for the control. Full article

(This article belongs to the Special Issue New Materials as Protective Coatings for Different Substrates (Wood, Stone, Paper, and Textile): Synthesis, Characterization Techniques and Their Applications)

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24 pages, 1774 KB

Open AccessArticle

Effect of Textile Structure and Lamination on the Thermo-Physiological Comfort of Automotive Seat Materials Under Seated Conditions

by Antonin Havelka, Md Tanzir Hasan, Michal Martinka and Adnan Mazari

Coatings 2026, 16(2), 267; https://doi.org/10.3390/coatings16020267 - 23 Feb 2026

Viewed by 396

Abstract

Thermo-physiological comfort of automotive seating is governed by the complex interaction between seat-cover materials, their structural configuration, and the heat and moisture exchange occurring at the seat–body interface during prolonged sitting. While numerous studies have examined individual textile constructions or isolated comfort parameters, [...] Read more.

Thermo-physiological comfort of automotive seating is governed by the complex interaction between seat-cover materials, their structural configuration, and the heat and moisture exchange occurring at the seat–body interface during prolonged sitting. While numerous studies have examined individual textile constructions or isolated comfort parameters, integrated evaluations combining objective material testing with dynamic microclimate measurements under realistic loading conditions remain limited. This study thoroughly examined six commercially important vehicle seat-cover materials that represent laminated, warp-knitted, and woven polyester architectures. Standardized laboratory techniques were used to quantify objective comfort qualities, such as air permeability, water vapor permeability, thermal resistance (Rct), and evaporative resistance (Ret) and transient heat flux test (H-test). Simultaneously, a multi-sensor system was used to constantly monitor temperature and relative humidity at the seat–body interface during sitting loading in a controlled subjective microclimate experiment at room temperature. The findings show that lamination technique and textile structure have a major impact on both transient microclimate behavior and steady-state material properties. Increased air and moisture transmission in warp-knitted and more open structures resulted in reduced evaporative resistance and more stable microclimate conditions. Denser laminated structures, on the other hand, exhibited more resistance to heat and evaporation, which led to a greater buildup of moisture when they were seated. Different temporal responses in temperature and humidity were also shown by the multi-sensor microclimate studies, underscoring the significance of assessing comfort beyond static material metrics. This study demonstrates that static thermos-physiological parameters alone are not sufficient to predict real stated comfort behavior. By integrating time-resolved microclimate analysis under realistic seated loading with standardized testing, a more reliable evaluation framework for automotive seat-cover comfort is proposed. Full article

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19 pages, 3697 KB

Open AccessArticle

Study on Macroscopic Mechanical Properties and Microscopic Mechanism of Drilling Cuttings Solidified by Alkali-Activated Furnace Ash

by Achen Qi, Pei Wang, Yuanjie Zhu, Wei Liu, Jianghua Jia, Zixuan Wang, Wenjun Hu and Yumei Liu

Coatings 2026, 16(2), 266; https://doi.org/10.3390/coatings16020266 - 23 Feb 2026

Viewed by 326

Abstract

To promote the resource utilization of oilfield solid waste and facilitate the green and low-carbon transformation of transportation infrastructure, this study employed drilling cuttings from the Maye area of the Xinjiang oilfield and coal-fired furnace ash as primary raw materials. NaOH, Na₂ [...] Read more.

To promote the resource utilization of oilfield solid waste and facilitate the green and low-carbon transformation of transportation infrastructure, this study employed drilling cuttings from the Maye area of the Xinjiang oilfield and coal-fired furnace ash as primary raw materials. NaOH, Na₂O·nSiO₂, and Ca(OH)₂ were used as alkali activators to prepare alkali-activated solidification materials for oilfield road base applications. The optimal curing system identified in this study (4 wt.% NaOH + 20 wt.% furnace ash) falls within the commonly reported dosage ranges for alkali-activated solid-waste materials, where NaOH contents are typically 3%–8% and furnace ash contents 15%–30%. Considering the distinct chemical characteristics of the Xinjiang oilfield solid wastes, a targeted optimization strategy was adopted to achieve a balance between mechanical performance and economic feasibility. Based on mix-proportion experiments, macroscopic mechanical properties were evaluated. In combination with X-ray diffraction (XRD), laser particle size analysis, simultaneous thermal analysis (TG–DSC), and scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM–EDS), the influence of activator type on both mechanical performance and microstructural evolution was systematically investigated. The results indicate that the system containing 4 wt.% NaOH + 20 wt.% furnace ash exhibits the best overall performance, achieving a 28-day compressive strength of 4.81 MPa and a splitting tensile strength of 0.41 MPa, which are significantly higher than those of the Na₂O·nSiO₂ system (3 wt.% Na₂O·nSiO₂ + 20 wt.% furnace ash) and the Ca(OH)₂ system (4 wt.% Ca(OH)₂ + 15 wt.% furnace ash). The primary hydration products were identified as C-(N)-A-S-H and C-S-H gels. The type of alkali activator plays a decisive role in regulating hydration reaction kinetics and the spatial distribution of Ca and Si elements, thereby governing the hierarchical differences in macroscopic mechanical properties. In particular, NaOH generates a highly alkaline environment that promotes the dissolution of active Si/Al components in both drilling cuttings and furnace ash, enhances gel polymerization, and results in a denser microstructure. This study provides theoretical and technical support for the high-value utilization of oilfield solid wastes in highway base engineering. Full article

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

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16 pages, 2534 KB

Open AccessArticle

A Mechanism–Data Hybrid Approach for Predicting Energy Consumption in CNC Machine Tools

by Guangchao Lu, Qin Shui, Guangjun Chen, Yingnan Zhu, Haiqin Cui and Yue Meng

Coatings 2026, 16(2), 265; https://doi.org/10.3390/coatings16020265 - 23 Feb 2026

Viewed by 737

Abstract

Accurate predictions of CNC machine tool energy consumption are crucial for sustainable manufacturing but remain challenging due to complex nonlinear dynamics. This paper proposes a mechanism–data hybrid framework combining physical modeling with an Attention–LSTM network. Unlike existing parallel hybrid models, this approach embeds [...] Read more.

Accurate predictions of CNC machine tool energy consumption are crucial for sustainable manufacturing but remain challenging due to complex nonlinear dynamics. This paper proposes a mechanism–data hybrid framework combining physical modeling with an Attention–LSTM network. Unlike existing parallel hybrid models, this approach embeds the mechanism model’s output as a strong prior into the neural network, explicitly guiding the learning of nonlinear residuals. First, a hierarchical decoupled mechanism model is constructed to establish the physical baseline of energy consumption. Second, an Attention–LSTM network is designed to compensate for dynamic errors caused by tool wear and thermal variations. Finally, experimental validation on a three-axis CNC milling machine demonstrates that the proposed method significantly outperforms meaningful baselines, achieving a Root Mean Square Error (RMSE) of 0.0610 and an R² of 0.9936. The framework provides a robust, physically interpretable solution for energy monitoring in intelligent manufacturing systems. Full article

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

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18 pages, 2154 KB

Open AccessArticle

Shear Behavior and Interface Damage Mechanism of Basalt FRP Bars: Experiment and Statistical Damage Constitutive Modeling

by Fengjun Liu, Pengfei Zhang, Jinjun Guo and Yanqing Wei

Coatings 2026, 16(2), 264; https://doi.org/10.3390/coatings16020264 - 21 Feb 2026

Viewed by 369

Abstract

The shear behavior of basalt fiber-reinforced polymer (BFRP) bars is crucial for their applications in geotechnical reinforcement and composite structures. In this study, double-side direct shear tests were conducted to investigate the progressive failure mechanism of BFRP bars. The results reveal a three-stage [...] Read more.

The shear behavior of basalt fiber-reinforced polymer (BFRP) bars is crucial for their applications in geotechnical reinforcement and composite structures. In this study, double-side direct shear tests were conducted to investigate the progressive failure mechanism of BFRP bars. The results reveal a three-stage process: initial matrix-dominated vertical shear, followed by fiber-bridging dominated oblique tension-shear, and finally formation of a “brush-like” fracture surface with significant residual strength. The average peak shear strength of the ten specimens was 204.04 MPa with a coefficient of variation of 7.25%, while the initial shear modulus averaged 3.37 GPa with a coefficient of variation of 11.82%. Based on statistical damage theory, a shear constitutive model incorporating fiber bridging and residual strength is established. Parameter analysis indicates that the shape parameter m governs the post-peak softening rate, while the residual strength τ_res essentially determines the height of the residual plateau. The model achieves a goodness-of-fit (R²) exceeding 0.98 for most specimens, accurately describing the mechanical behavior from linear elasticity, damage-induced hardening, peak softening, to the residual stage. This study provides theoretical and experimental support for the engineering application of BFRP bars under complex stress states. Full article

(This article belongs to the Special Issue Microstructure, Mechanical Properties and Surface Engineering for Construction and Building Materials)

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22 pages, 8223 KB

Open AccessFeature PaperArticle

Tribological Properties of AISI 420 ESR Stainless Steel Modified by Sequential Boriding and Nitriding

by Melvyn Alvarez Vera, Rafael Carrera Espinoza, Valeria López López, Marc Wettlaufer, Stefan Barth, Juan Carlos Díaz Guillén, Héctor Manuel Hernández García, Rita Muñoz Arroyo, Javier A. Ortega, Pablo Moreno Garibaldi and Marco A. Cruz-Gómez

Coatings 2026, 16(2), 263; https://doi.org/10.3390/coatings16020263 - 21 Feb 2026

Viewed by 478

Abstract

This study investigates the effects of surface thermochemical treatments using boriding, nitriding, and boronitriding on the microstructure and mechanical properties of martensitic stainless steel AISI 420 ESR. Powder-pack boriding, gas nitriding, and sequential boronitriding processes were applied to enhance surface hardness, wear resistance, [...] Read more.

This study investigates the effects of surface thermochemical treatments using boriding, nitriding, and boronitriding on the microstructure and mechanical properties of martensitic stainless steel AISI 420 ESR. Powder-pack boriding, gas nitriding, and sequential boronitriding processes were applied to enhance surface hardness, wear resistance, and adhesion. The microstructural and mechanical properties of the surface samples were analyzed using scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, microhardness, and nanoindentation testing. Tribological behavior was analyzed using a pin-on-disk tribometer under dry-sliding wear conditions, with applied normal loads of 5 N and 10 N and a sliding distance of 1000 m. The results showed that the borided samples exhibited the highest surface hardness, up to 1182 HV_0.05, as well as brittle fracture and spallation with poor adhesion, while the boronitrided layer offered excellent adhesion. The boronitriding condition demonstrated a synergistic balance, combining high wear resistance (5.92 × 10⁻⁷ mm³N⁻¹m⁻¹ and 4.96 × 10⁻⁷ mm³N⁻¹m⁻¹) and reduced friction (~0.78 and ~0.67) for loads of 5 N and 10 N, respectively, without brittle fractures on the coating layer. These results confirm that duplex coating treatment is an effective strategy for improving the surface performance of AISI 420 ESR components subjected to severe operating conditions. Full article

(This article belongs to the Special Issue Advances in Protective Coatings for Metallic Surfaces)

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21 pages, 12415 KB

Open AccessArticle

Novel Adhesive Film for Glyoxal-Dehydrated Lacquerware: Composite Modification of Natural Lacquer with Soy Protein Isolate and Nano-SiO₂

by Zifan Chen, Xiaolong Zhang, Peng Xia, Xiaohan Qi, Xueling Zou and Shuya Wei

Coatings 2026, 16(2), 262; https://doi.org/10.3390/coatings16020262 - 21 Feb 2026

Viewed by 340

Abstract

A novel composite adhesive for lacquer film restoration was developed by modifying natural lacquer with Tween-20, soy protein isolate (SPI), and nano-SiO₂ to address the bonding failure and interfacial instability of glyoxal-dehydrated lacquerware. The optimal formulation (70% lacquer, 10% Tween-20, 15% SPI, [...] Read more.

A novel composite adhesive for lacquer film restoration was developed by modifying natural lacquer with Tween-20, soy protein isolate (SPI), and nano-SiO₂ to address the bonding failure and interfacial instability of glyoxal-dehydrated lacquerware. The optimal formulation (70% lacquer, 10% Tween-20, 15% SPI, 5% nano-SiO₂) achieved a shear bond strength of 3.8 ± 0.3 MPa, corresponding to a 58% increase compared with pure lacquer (2.4 ± 0.2 MPa). After 30 days of immersion in a pH 4.0 acidic solution, the adhesive retained 91 ± 3% of its initial shear strength, significantly higher than that of pure lacquer (65 ± 5%). Under accelerated aging conditions (50 °C and 95% relative humidity), the composite adhesive exhibited minimal weight gain (1.0 ± 0.2%) and no visible mold growth, whereas pure lacquer showed greater moisture uptake (3.0 ± 0.4%) accompanied by evident fungal colonization. The cured film displayed good color compatibility (ΔE ≈ 2.0) and improved flexibility (elongation at break: 12.5% vs. 4.2%). XPS and FTIR analyses suggested enhanced interfacial bonding through hydrogen-bond interactions and possible Si–O–C linkages at the wood–lacquer interface. Practical restoration of a Warring States period lacquer ear cup (China) demonstrated effective and stable reattachment of detached fragments with satisfactory visual integration and long-term durability. Overall, this work provides a compatible and durable material strategy for the conservation of glyoxal-dehydrated lacquerware. Full article

(This article belongs to the Special Issue New Insights into Everyday Heritage: Surface Analysis and Conservation)

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21 pages, 4893 KB

Open AccessArticle

Modeling Wear of KNA-82 Coatings with 0.5% Yttrium for Radial Seals of Gas Turbine Engines

by Vitaliy Kulikov, Vadim Kubich, Yelyzaveta Fasol, Oleg Cherneta, Svetlana Kvon, Aristotel Issagulov, Saniya Arinova and Olga Zharkevich

Coatings 2026, 16(2), 261; https://doi.org/10.3390/coatings16020261 - 20 Feb 2026

Viewed by 352

Abstract

The paper presents the results of a study of linear wear of gas-flame and ion-plasma coatings of KNA-82 seals with an yttrium content of 0.5%, used in gas turbine engine assemblies, during physical modeling of their thermomechanical loading on small-sized samples. Tribotechnical tests [...] Read more.

The paper presents the results of a study of linear wear of gas-flame and ion-plasma coatings of KNA-82 seals with an yttrium content of 0.5%, used in gas turbine engine assemblies, during physical modeling of their thermomechanical loading on small-sized samples. Tribotechnical tests were carried out in four stages, simulating the operating conditions of real gas turbine engines—from the first start-up with running-in of the coating cut-in areas to reaching a steady state with their service properties formed. The surface of the coatings was in contact with the ridges of triangular-shaped plates without heating (20 °C), at average heating (350–470 °C), after holding the samples at 1100 °C and average heating of 410–460 °C, and after grinding off the worn layer that had worn out after holding the samples at 1100 °C at average heating of 320–440 °C. Trends in the change in the linear ear of coatings and the formation of friction tracks caused by the uneven manifestation of the physical and mechanical properties of coatings, which are unevenly distributed throughout their body, were determined. It was found that both coatings tend to stabilize the wear process at certain mechanical pressures in the friction contact zone and only in the temperature range from 20 °C to 400 °C. These pressures range from 4 MPa to 6.7 MPa for gas-flame coatings and from 3 MPa to 4.2 MPa for ion-plasma coatings. It has been determined that within the depth range of 30–100 μm, the wear resistance (as assessed by linear wear) of ion-plasma coatings is higher than that of gas-flame coatings. This predetermines the fact that in the event of a catastrophic collision between the coatings and a blade, the geometry of the damage to the surface of the gas-flame coating will be greater than that of the ion-plasma coating. In the event of damage exceeding 75–100 μm in depth, both coatings become inoperable, since their wear characteristics are no longer maintained. This is indicated by a rapid decrease in their wear resistance under step loading. Moreover, the gas-flame coating is more prone to catastrophic failure than the ion-plasma coating. Full article

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

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16 pages, 3031 KB

Open AccessFeature PaperArticle

Multi-Scale Copper–Cobalt-Supported Carbon Catalysts for Efficient CO₂ and O₂ Reduction

by Lingke Sun, Wenqi Song, Yangfei Wang and Yujun Song

Coatings 2026, 16(2), 260; https://doi.org/10.3390/coatings16020260 - 19 Feb 2026

Viewed by 565

Abstract

A sequenced ultrasonic atomization coupled with a pyrolysis process is developed to synthesize a series of cross-scale (Co/Cu)-NC catalysts. The catalysts demonstrate high metal utilization efficiency with a metal loading of 22.45 ± 0.07 wt%. Electrochemical evaluations for the oxygen reduction reaction (ORR) [...] Read more.

A sequenced ultrasonic atomization coupled with a pyrolysis process is developed to synthesize a series of cross-scale (Co/Cu)-NC catalysts. The catalysts demonstrate high metal utilization efficiency with a metal loading of 22.45 ± 0.07 wt%. Electrochemical evaluations for the oxygen reduction reaction (ORR) suggest that the best (Co/Cu)-NC catalysts are prepared with a Co/Cu ratio of 1/1 and a calcination temperature of 800 °C, which achieve a half-wave potential of 0.87 V and an electrochemical impedance spectroscopy semicircle radius as low as 30 ohms. Linear sweep voltammetry measurements indicate that (Co/Cu)-NC catalysts exhibit the highest current density. Under a potential of −0.73 V versus the reversible hydrogen electrode, (Co/Cu)-NC catalysts demonstrate long-term stability with the CO Faradaic efficiency of about 70% for catalyzing carbon dioxide reduction reaction (CO₂RR). Overall, the above metrics identify CoCu-800 as the optimal bifunctional catalyst among the tested samples for ORR and CO₂RR under the investigated conditions. Full article

(This article belongs to the Special Issue Environmentally Friendly Energy Conversion Materials and Thin Films)

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32 pages, 4357 KB

Open AccessFeature PaperArticle

Magnetic Activated Carbon Functionalized with Polyaniline for Efficient Pb (II) Adsorption from Aqueous Solutions

by Mahmoud M. Youssif, Kamil Kornaus and Marek Wojnicki

Coatings 2026, 16(2), 259; https://doi.org/10.3390/coatings16020259 - 19 Feb 2026

Viewed by 430

Abstract

Lead (Pb) contamination in water poses a significant threat to both human health and the environment as it is toxic even at very minimal concentrations. In the scope of this study, a novel magnetic composite material, AC/Fe₃O₄/PANI-SDS, was synthesized [...] Read more.

Lead (Pb) contamination in water poses a significant threat to both human health and the environment as it is toxic even at very minimal concentrations. In the scope of this study, a novel magnetic composite material, AC/Fe₃O₄/PANI-SDS, was synthesized to efficiently eliminate Pb²⁺ ions from polluted water. Each component of the composite has a significant impact: the activated carbon provides a large surface area for adsorption, the magnetic iron oxide (Fe₃O₄) allows easy magnetic recovery from water systems using a magnet, and the polyaniline (PANI) and sodium dodecyl sulfate (SDS) improve the capability of the material to attract and hold onto Pb²⁺ ions. To assess the surface, magnetic, and structural properties of the prepared material, several characterization techniques were applied, such as FTIR, XRD, SEM-EDS, BET analysis, VSM, and zeta potential measurements. These tests confirmed that the composite has the right structure and functional groups to perform as a capable and efficient adsorbent. Batch adsorption studies were used to evaluate the effects of pH, interaction time, initial Pb²⁺ ion concentration, and temperature on removal efficiency. The findings highlight the composite’s remarkable adsorption efficiency after 220 min under optimal conditions, specifically at pH 6. Adsorption kinetic studies demonstrated strong agreement with the pseudo-second-order model, while isotherm analysis showed that the Langmuir model provided the highest correlation coefficient within the investigated concentration range. This fitting suggested apparent Langmuir-type adsorption behavior, with a maximum adsorption capacity of 348.39 mg/g. Thermodynamic assessment demonstrated that the elimination of Pb²⁺ ions is an endothermic and spontaneous process. In addition, the composite can be reused and recycled repeatedly without significantly reducing its effectiveness, offering an economical and ecologically sustainable approach. The findings of this research highlight the potential of the AC/Fe₃O₄/PANI-SDS composite as a new, efficient, and eco-friendly adsorbent for the elimination of Pb²⁺ ions from solutions. In real-world applications, its high capacity for adsorption, ease of separation, and reusability make it a promising treatment for heavy metal contamination. Full article

(This article belongs to the Special Issue Advanced Catalytic Coatings and Films for High-Performance Applications)

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17 pages, 6463 KB

Open AccessArticle

An Experimental Study of Surface Icing Characteristics on Offshore Wind Turbine Blades: Effects of Salinity and Liquid Water Content

by Qinghui Wang, Yuxiao Dong, Jincheng Li, Ze Zhang and Fang Feng

Coatings 2026, 16(2), 258; https://doi.org/10.3390/coatings16020258 - 19 Feb 2026

Viewed by 405

Abstract

Offshore wind turbine blades operating in cold climates are frequently affected by surface icing, which compromises aerodynamic performance and reduces power output. To address this challenge, the present study conducted controlled icing wind tunnel experiments to investigate how salinity and liquid water content [...] Read more.

Offshore wind turbine blades operating in cold climates are frequently affected by surface icing, which compromises aerodynamic performance and reduces power output. To address this challenge, the present study conducted controlled icing wind tunnel experiments to investigate how salinity and liquid water content (LWC) influence ice formation on the S809 airfoil surface. Results indicate that increased salinity substantially inhibits ice accretion: as salinity rises from 0‰ to 35‰, the total icing area rate drops by approximately 20.5% within 6 min, and the maximum ice thickness declines from 17.21 mm to 6.03 mm. Conversely, LWC emerges as a dominant factor intensifying icing severity: raising LWC from 0.5 g/m³ to 1.5 g/m³ leads to a 135% increase in icing area and an increase in maximum ice thickness from 7.69 mm to 18.17 mm. A notable synergistic interaction is observed—higher LWC enhances the inhibitory effect of salinity on ice formation. These findings offer valuable insights into the icing dynamics under marine atmospheric conditions and provide a theoretical foundation for the development of anti-icing strategies for offshore wind turbine blades. Full article

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

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19 pages, 3369 KB

Open AccessFeature PaperArticle

Rheological Properties of Bitumen and Asphalt Mixtures Realised in Varying Laboratory and in Situ Ageing Protocols

by Dilimulati Aili, Jing Zhang, Zhengxun Wei, Yuan Ling, Junwu Wang, Hua Mao and Wei Si

Coatings 2026, 16(2), 257; https://doi.org/10.3390/coatings16020257 - 18 Feb 2026

Viewed by 397

Abstract

Ageing significantly affects the long-term durability of asphalt pavements, yet quantitative correlations between laboratory ageing protocols and actual field ageing remain insufficiently defined. This study investigates the ageing behaviour of an 80/100 penetration-grade bitumen at binder, mixture, and field levels to establish equivalence [...] Read more.

Ageing significantly affects the long-term durability of asphalt pavements, yet quantitative correlations between laboratory ageing protocols and actual field ageing remain insufficiently defined. This study investigates the ageing behaviour of an 80/100 penetration-grade bitumen at binder, mixture, and field levels to establish equivalence relationships among different ageing pathways. Binder samples were subjected to RTFO, PAV (20–60 h), and coupled thermal–photo-oxidative ageing (RTFO + PAV + UV, 6–18 d). Asphalt mixtures were oven-aged at 85 °C for 5–10 d, followed by binder extraction and recovery, and field-aged binders were obtained from a 12-year-old pavement in Xinjiang, China. Rheological properties were characterised using frequency sweep and multiple stress creep and recovery tests, from which ageing index (AI), low-temperature ageing index (LAI), Glover–Rowe (G–R) parameter, and nonrecoverable compliance (J_nr) were derived. AI increased from 1.00 for virgin binder to 1.12 under coupled ageing, while G–R increased from near zero to 318 kPa after 60 h PAV ageing and exceeded 400 kPa under coupled ageing. UV exposure increased G–R by approximately 20%–65% relative to thermal ageing alone. Nonlinear growth models described property evolution with high reliability (R² = 0.995–0.999). Equivalent ageing analysis showed that RTFO + PAV required over 50 h to reproduce field ageing, whereas coupled ageing and mixture oven ageing achieved comparable states within shorter durations. These results demonstrate that photo-oxidation and mixture-scale interactions significantly influence ageing pathways and should be considered in laboratory simulations of field ageing. Full article

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

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17 pages, 2724 KB

Open AccessArticle

Mix Design and Performance Regulation of Calcium Carbide Slag–Silica Fume-Based Lightweight Fluid Solidified Soil

by Yongkang Wang, Qicheng Jian, Jikai Fu, Xianghui Kong, Jiaxiang Fang, Lipeng Lu, Maolin Wang and Yilong Li

Coatings 2026, 16(2), 256; https://doi.org/10.3390/coatings16020256 - 18 Feb 2026

Viewed by 561

Abstract

Calcium carbide slag and silica fume was used as a cement replacement material, combined with excavated soil and EPS (expanded polystyrene) particles, to develop a new green and low-carbon lightweight fluid solidified soil (LFSS). Focusing on the performance regulation of LFSS, this study [...] Read more.

Calcium carbide slag and silica fume was used as a cement replacement material, combined with excavated soil and EPS (expanded polystyrene) particles, to develop a new green and low-carbon lightweight fluid solidified soil (LFSS). Focusing on the performance regulation of LFSS, this study adopted the paste volume ratio (PV, defined as the volume ratio of paste to total mixture) and the water–binder ratio (w/b) to systematically construct a mix ratio design system and proposed EPS particle interface modification and shell formation technology to improve the weak interface bonding between EPS and the matrix. Firstly, based on the paste volume method, the effects of PV and w/b on the flowability and strength of LFSS were analyzed, and a linear correlation model between the water–solid volume ratio and flowability, as well as a quadratic function prediction model for 28-day strength, was established. Secondly, the “core–shell structure” of EPS particles was constructed by combining EVA (ethylene-vinyl acetate) modification with the coating of calcium carbide slag–silica fume paste. Considering the influence of the coating method, w/b, and material mass ratio on interface bonding comprehensively, the optimal process parameters were determined to achieve the interface reinforcement of EPS particle. The results showed that the water–solid volume ratio was significantly linearly correlated with the flowability of LFSS. PV and w/b respectively controlled the framework formation and pore structure evolution of LFSS, with optimal overall performance at PV = 0.55 and w/b = 2.5. The modification shell formation significantly reduced the shell loss rate of EPS particles and increased the 28-day compressive strength of LFSS by 21.7%. SEM (scanning electron microscope) and EDS (energy-dispersive spectroscopy) analysis further revealed that the shell-formation technique promoted the densification of the interface transition zone, enhanced the deposition of hydration products, and strengthened the synergistic effect of Na and Ca elements, thereby significantly improving interface bonding and overall structural stability. This study established a “mix ratio optimization-modification and shell formation” dual-regulation mechanism, providing an effective technical approach and theoretical basis for the engineering application of calcium carbide slag–silica fume-based LFSS. Full article

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

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23 pages, 3887 KB

Open AccessFeature PaperArticle

Rheology-Driven Quantification and Mechanistic Insight into Binder-Filler Interactions in Asphalt Mastics Incorporating Raw and Calcined Oyster Shell Powders

by Ruihai Wang, Xiang Liu, Yudong Dang, Xiaolong Li and Jie Chen

Coatings 2026, 16(2), 255; https://doi.org/10.3390/coatings16020255 - 18 Feb 2026

Viewed by 415

Abstract

Waste oyster shell powder (OP) and calcined oyster shell powder (COP) were used as bio-fillers in asphalt mastics. Limestone powder (LP) served as the control. This study employed rheological theory to quantify filler–asphalt interactions. Dynamic shear rheometry (DSR), Black diagrams, and master curves [...] Read more.

Waste oyster shell powder (OP) and calcined oyster shell powder (COP) were used as bio-fillers in asphalt mastics. Limestone powder (LP) served as the control. This study employed rheological theory to quantify filler–asphalt interactions. Dynamic shear rheometry (DSR), Black diagrams, and master curves were analyzed to determine critical volume fraction (φ_crit), interaction parameter (C), and complex viscosity increment (∆η*). Results indicate that OP mastics exhibit the lowest φ_crit (0.510) and highest C value (1.133), demonstrating the strongest interfacial interaction. COP shows intermediate interaction strength (φ_crit = 0.542), yet both OP and COP outperform LP (φ_crit = 0.617) in high-temperature deformation resistance within the 0.23–0.53 filler volume fraction range, evidenced by superior complex shear modulus (G*) master curves and pronounced ∆η* increases. Grey relational analysis identifies specific surface area and CaCO₃ content as governing factors. Optical microscopy and FTIR confirm that filler–asphalt interactions are dominated by physical adsorption without chemical bond formation. These findings elucidate the performance advantages of both raw and calcined oyster shell powders and provide a theoretical basis for their application as sustainable high-performance bio-fillers in asphalt pavements. Full article

(This article belongs to the Special Issue Advanced Nano-Structured Hard Coatings: Applications and Characterization)

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19 pages, 9364 KB

Open AccessArticle

Design of a Novel Surface-Applied Protective Grout with Superior Sulfate Resistance

by Huian Shao, Kai Cui, Xiangpeng Yu, Pengfei Xu and Chengrui Ge

Coatings 2026, 16(2), 254; https://doi.org/10.3390/coatings16020254 - 16 Feb 2026

Viewed by 394

Abstract

The degradation of building foundations, underground structures, and historical fabrics in sulfate-laden environments poses a persistent threat to the durability and safety of the built environment. Developing effective, sustainable repair materials is of paramount importance. This study presents the development, systematic optimization, and [...] Read more.

The degradation of building foundations, underground structures, and historical fabrics in sulfate-laden environments poses a persistent threat to the durability and safety of the built environment. Developing effective, sustainable repair materials is of paramount importance. This study presents the development, systematic optimization, and performance validation of a novel micro-expansive grout designed for high durability in aggressive sulfate conditions. The grout formulation utilizes industrial by-product fly ash, quicklime, and site-compatible soils, emphasizing sustainability. Nine chemical admixtures were screened for sulfate resistance enhancement. Laboratory experiments rigorously characterized the effects of water-to-solid ratio and admixture dosage on fresh-state properties (fluidity, setting time) and hardened-state performance (volumetric stability). To resolve a multi-objective optimization problem balancing injectability, dimensional compatibility, and cost-effectiveness, an integrated multi-criteria decision-making (MCDM) framework combining FAHP, MII, CRITIC, and TOPSIS was employed. This data-driven methodology identified an optimal formulation incorporating 3% disodium hydrogen phosphate (DSP) at a 0.58 water-to-solid ratio. The optimized grout exhibited a flow value of 75 mm, ensuring excellent injectability within the target range (40–120 mm), and an expansion rate of 7.67%, which falls within the safe range (0%–10%) to ensure dimensional compatibility. Accelerated durability tests via cyclic immersion in sodium sulfate solution demonstrated the optimized grout’s exceptional resistance to sulfate attack, retaining approximately 88% of its compressive strength after 15 aggressive cycles. The balanced properties and validated durability indicate strong potential for this grout in demanding repair scenarios. One key example is the repair of fissures in earthen heritage structures, which requires extreme material compatibility and long-term performance. Full article

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

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19 pages, 3761 KB

Open AccessArticle

Adhesion Mechanism and Quantitative Evaluation of Bio-Based and Petroleum-Based Oil-Modified Asphalt

by Wei Zhang, Xiao Ye, Mingwei Liu, Yongchang Cui, Lei Zhang and Haoan Wang

Coatings 2026, 16(2), 253; https://doi.org/10.3390/coatings16020253 - 16 Feb 2026

Viewed by 327

Abstract

The utilization of waste and renewable oils as asphalt modifiers is a crucial strategy for achieving sustainable development in pavement engineering. However, the different physicochemical effects exerted by oil sources (bio-based versus petroleum-based) on the asphalt–aggregate interface remain insufficiently understood. This study aims [...] Read more.

The utilization of waste and renewable oils as asphalt modifiers is a crucial strategy for achieving sustainable development in pavement engineering. However, the different physicochemical effects exerted by oil sources (bio-based versus petroleum-based) on the asphalt–aggregate interface remain insufficiently understood. This study aims to elucidate the influence mechanism of two bio-based oils and two petroleum-based oils on asphalt adhesion and the pavement performance of mixtures. A quantitative evaluation method combining the boiling test with digital image processing (DIP) technology was developed to assess the anti-stripping performance of modified asphalt on different lithological aggregates (acidic granite and alkaline limestone). Additionally, Fourier transform infrared spectroscopy (FTIR) was employed to reveal the chemical evolution of the modified asphalt. The results indicated that, although all oil-based modifiers demonstrated excellent compatibility and storage stability with the base asphalt (segregation ratio < 5%), their adhesion properties were significantly influenced by aggregate lithology. The key finding was that, compared to petroleum-based oils, bio-based oils exhibited superior adhesion performance on acidic granite surfaces, markedly mitigating moisture-induced stripping. FTIR analysis confirmed that this enhancement was attributable to the aromatic and carbonyl functional groups introduced by bio-based oils, which effectively promoted the interfacial bonding. Furthermore, bio-oil-modified mixtures exhibited optimal low-temperature cracking resistance without compromising high-temperature stability. These findings elucidate the mechanism by which bio-oil enhances the water-damage resistance of acidic aggregate systems, providing a theoretical basis for the optimized selection of sustainable asphalt modifiers. Full article

(This article belongs to the Topic Service Safety and Green Maintenance Technology for Road Infrastructure in Complex Environments)

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18 pages, 2454 KB

Open AccessFeature PaperArticle

Finite Element Analysis of Contact Radius and Young’s Modulus Bias in Polymer Indentation

by Laisvidas Striska, Rimantas Stonkus, Dainius Udris, Sonata Tolvaisiene, Rokas Astrauskas, Nikolajus Kozulinas, Rokas Bagdonas, Evaldas Balciunas, Inga Morkvenaite and Arunas Ramanavicius

Coatings 2026, 16(2), 252; https://doi.org/10.3390/coatings16020252 - 16 Feb 2026

Viewed by 795

Abstract

Contact mechanics models are often inaccurate, due to (i) unknown contact radius, (ii) mechanical models not parameterizing it, (iii) in some models it is neither assumed meaningfully nor determined, and (iv) uncertain probe radius arising from manufacturer-specified nominal values and manufacturing tolerances. In [...] Read more.

Contact mechanics models are often inaccurate, due to (i) unknown contact radius, (ii) mechanical models not parameterizing it, (iii) in some models it is neither assumed meaningfully nor determined, and (iv) uncertain probe radius arising from manufacturer-specified nominal values and manufacturing tolerances. In this paper, an FEA model was used to quantify the evolution of the contact radius during indentation for two probe geometries: a pyramidal indenter (TRIANG2 nominal apex radius 2 nm) and a flat-ended punch (FLAT4000; nominal punch radius 4000 nm) on poly (vinyl chloride) (PVC), for which Young’s modulus (E_ref) was obtained by a standard mechanical tensile method. The effective contact radius,

R_{e f f}

, determined from FEA, was subsequently used in a Hertz-based force–indentation parametrization. Uncertainty in the probe apex radius due to manufacturer tolerances was addressed by SEM measurement of the conical tip, enabling assessment of its impact on the modulus estimated from AFM indentation. Based on these results, we propose a practical, geometry-aware analysis methodology that is transferable across probe geometries. The effective contact radius,

R_{e f f}

, is first established using a well-characterized reference material and subsequently applied to a mechanical model to extract Young’s modulus. In this approach, the Hertz-based parametrization is used as a consistent mathematical framework, while the effective contact radius accounts for probe-dependent contact evolution. Full article

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

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22 pages, 11942 KB

Open AccessArticle

Experimental and Numerical Study on the Flexural Performance of Reinforced Concrete Beams with 630 MPa High-Strength Rebars

by Xingxin Li, Ruifeng Cao and Ying Meng

Coatings 2026, 16(2), 250; https://doi.org/10.3390/coatings16020250 - 16 Feb 2026

Viewed by 354

Abstract

The use of high-strength reinforcing steel is an effective way to improve the flexural efficiency of reinforced concrete beams. However, the flexural behaviour of beams reinforced with 630 MPa grade longitudinal rebars in combination with normal-strength concrete is still not fully understood, especially [...] Read more.

The use of high-strength reinforcing steel is an effective way to improve the flexural efficiency of reinforced concrete beams. However, the flexural behaviour of beams reinforced with 630 MPa grade longitudinal rebars in combination with normal-strength concrete is still not fully understood, especially with regard to serviceability performance. In this study, the flexural performance of simply supported RC beams reinforced with HRB500, HRB600 and HRB630 longitudinal rebars and cast with C60 steel-fibre-reinforced concrete was investigated through a combined experimental and numerical approach. Six beams were tested under four-point bending to examine cracking patterns, deflection development and ultimate flexural capacity. A three-dimensional nonlinear finite element model based on the Concrete Damage Plasticity model in ABAQUS was then established and calibrated against the test data. Using the validated numerical model, a parametric study was carried out to investigate the influence of steel grade, tensile reinforcement ratio on flexural stiffness and ductility. Test results indicate that, for the same reinforcement ratio, the ultimate moment capacity of HRB630 beams is about 8% higher than that of HRB600 beams and about 25% higher than that of HRB500 beams, while a ductile flexural failure mode governed by yielding of tension reinforcement is still maintained. The study also shows that for HRB630 beams, deflection predictions need to account for the higher steel stress level and the deterioration of tension stiffening effects. In general, the results demonstrate that HRB630 high-strength rebars can be safely and efficiently used in flexural members when the tensile reinforcement ratio is kept within the under-reinforced range and steel-fibre-reinforced concrete is adopted to improve cracking and deflection performance. Full article

(This article belongs to the Special Issue Advanced Technologies in Durability Enhancement of Concrete: Coatings, Low-Carbon Cements, Additives and Admixtures)

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22 pages, 42228 KB

Open AccessArticle

The Mechanism of Surface Blackening and Deterioration of a Traditional Construction Material, CATC, for Coastal Stone Masonry Jointing

by Yuhong Ding, Li Chen, Yili Fu, Yujing Lai, Tengfei Ma and Ruiming Guan

Coatings 2026, 16(2), 251; https://doi.org/10.3390/coatings16020251 - 15 Feb 2026

Viewed by 388

Abstract

Crust Ash Triad Clay (CATC) is a traditional construction material commonly used for jointing coastal stone masonry in Southeast China. Its surface is prone to blackening in coastal environments. This study focused on traditional stone masonry residences within the protection area of Quanzhou [...] Read more.

Crust Ash Triad Clay (CATC) is a traditional construction material commonly used for jointing coastal stone masonry in Southeast China. Its surface is prone to blackening in coastal environments. This study focused on traditional stone masonry residences within the protection area of Quanzhou Shihu Ancient Wharf. A systematic detection and analysis were conducted using combined technologies: XRD, Raman, SEM-EDS, and 16S rRNA sequencing. The results revealed that the CATC substrate is mainly composed of quartz and feldspar minerals, with calcite and other substances as binding components. The black coating on the surface is a loose material attached to the substrate, retaining some of the original minerals. The core mechanism of blackening lies in the coastal environment’s abundance of salt spray and humidity. The sulfate substances carried by rainwater react synergistically with metal ions such as Cu, Fe, and Mn in the substrate under the metabolic action of anaerobic bacteria, producing metal sulfide minerals. Photoautotrophic bacteria generate oxygen through photosynthesis, promoting the oxidation and acidification of metal sulfide. This process directly triggers the chain deterioration of the CATC substrate. Based on the principle of “minimal intervention”, physical waterproofing or laser stain removal can be implemented. This study provides scientific support for optimizing the durability and achieving precise protection of traditional building materials in coastal stone structure heritage. Full article

(This article belongs to the Special Issue New Insights into Everyday Heritage: Surface Analysis and Conservation)

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17 pages, 3096 KB

Open AccessReview

Employing Glycerol for Improving Diffraction Efficiency, Photosensitivity and Pressure Sensitivity in Holographic Recording Layers

by Emilia Mitkova Mihaylova

Coatings 2026, 16(2), 249; https://doi.org/10.3390/coatings16020249 - 14 Feb 2026

Viewed by 387

Abstract

The aim of this review is to explore the improvement in diffraction efficiency, photosensitivity and pressure sensitivity in holographic materials containing glycerol. Glycerol is a well-known, non-toxic, water-soluble polyol compound. Glycerol polymers have attracted increased attention recently due to the diversity of the [...] Read more.

The aim of this review is to explore the improvement in diffraction efficiency, photosensitivity and pressure sensitivity in holographic materials containing glycerol. Glycerol is a well-known, non-toxic, water-soluble polyol compound. Glycerol polymers have attracted increased attention recently due to the diversity of the available compositions. Glycerol provides access to a range of monomers for subsequent polymerizations. Various glycerol containing polymers, including polyvinyl alcohol films, polyesters, polyethers and polycarbonates, have been investigated for different applications. It was discovered in 2009 that the addition of glycerol to the composition of water-soluble holographic photopolymers facilitates the faster formation of holograms due to greater photosensitivity. It was also discovered that the presence of glycerol in holographic photopolymers makes them highly pressure-sensitive. A new family of holographic photopolymer materials, containing glycerol and capable of recording holograms with bright reflections, was reported. The novel photopolymers are composed of glycerol, a polymeric binder, a crosslinking monomer, an initiation system, and sensitising dyes. No wet-processing of holograms is necessary. Each holographic photopolymer film contains bis-acrylamide (BA) monomer in polyvinyl alcohol matrix, triethanolamine and methylene blue dye solution, glycerol and water. It was shown that the new holographic material is capable of reaching a refractive index modulation matching that of the well-known acrylamide photopolymer material, but more quickly. The new holographic photopolymer materials are cheap and environmentally friendly. The use of glycerol to improve diffraction efficiency, photosensitivity and pressure sensitivity in holographic recording layers continues to expand. This review describes the development and applications of glycerol-containing photopolymer materials. An environmentally friendly diacetone-based photopolymer was developed. The positive effect of glycerol on N-vinylpyrrolidone photopolymer was investigated. Finally, potential opportunities for future research in the area of glycerol-containing photopolymers are outlined. Full article

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

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34 pages, 5487 KB

Open AccessArticle

Study on Internal Flow Characteristics of Airless Spray Nozzles Based on an Improved Dynamic WALE Model

by Guichun Yang, Zhaojie Wu, Jiang Li, Weixing Hua, Gang Fang, Shiming Chen and Yan Chen

Coatings 2026, 16(2), 248; https://doi.org/10.3390/coatings16020248 - 14 Feb 2026

Viewed by 445

Abstract

Cavitation flow within airless spray nozzles critically influences both atomization quality and nozzle longevity. However, its highly transient and multiphase-coupled nature poses significant challenges to the predictive accuracy of turbulence models. To improve numerical simulation fidelity, this study develops an improved dynamic Wall-Adapting [...] Read more.

Cavitation flow within airless spray nozzles critically influences both atomization quality and nozzle longevity. However, its highly transient and multiphase-coupled nature poses significant challenges to the predictive accuracy of turbulence models. To improve numerical simulation fidelity, this study develops an improved dynamic Wall-Adapting Local Eddy-viscosity (WALE) subgrid-scale model for Large Eddy Simulation (LES). Building on the standard WALE formulation, the model incorporates a dynamic coefficient determined via the Germano identity and a least-squares approach, which enables it to adaptively capture the turbulence modulation effects induced by cavitation. Coupled with a Volume of Fluid (VOF) multiphase flow method, this framework is employed to systematically simulate the complex internal nozzle flow under varying spray pressures, coating viscosities, and surface tensions. Results indicate that the improved dynamic WALE model increases numerical stability by approximately 15% compared with the standard model. The internal flow can be partitioned into three regions: a potential-flow acceleration region, a cavitation-induced fluctuation region, and an outlet formation region. Within the cavitation-induced fluctuation region near the wall, cavitation generates a local double-peaked velocity profile and pronounced pressure pulsations. Cavitation intensity increases approximately linearly with spray pressure but decreases with increasing viscosity and surface tension. Both the discharge coefficient and velocity coefficient decrease linearly with increasing cavitation number, indicating that moderate cavitation can enhance instantaneous throughput by altering the flow-field structure. Finally, outflow mass-flow experiments validate the numerical model’s reliability: the improved dynamic WALE model achieves prediction errors ranging from 0.47% to 11.91%, substantially outperforming the standard WALE model, which has errors ranging from 1.27% to 21.10%. Full article

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

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20 pages, 12762 KB

Open AccessArticle

Regulating Microstructure Evolution and Strengthening Mechanisms in Al-Zn-Mg-Cu Alloy via Pre-Aging Treatment

by Jingchuan Tang, Kai Zhang and Ruiqing Li

Coatings 2026, 16(2), 247; https://doi.org/10.3390/coatings16020247 - 14 Feb 2026

Viewed by 312

Abstract

This study significantly enhances the mechanical properties of an Al-Zn-Mg-Cu alloy through the implementation of a pre-aging process. By optimizing the microstructure of the Al-Zn-Mg-Cu alloy with different pre-aging treatments, the evolution of the microstructure and mechanical properties of the alloy initially containing [...] Read more.

This study significantly enhances the mechanical properties of an Al-Zn-Mg-Cu alloy through the implementation of a pre-aging process. By optimizing the microstructure of the Al-Zn-Mg-Cu alloy with different pre-aging treatments, the evolution of the microstructure and mechanical properties of the alloy initially containing GP I, GP II, and η′ phases is systematically investigated during aging at 140 °C. The experimental results show that, under the three pre-aging processes, the peak tensile strengths are 590.8 MPa, 594.0 MPa, and 612 MPa, respectively, while the corresponding elongation rates are 8.2%, 8.4%, and 10.3%. When pre-aging produces an initial microstructure containing GP I and GP II, these GP zones rapidly coarsen within the grains during subsequent aging. This makes it difficult for solute atoms to diffuse to the grain boundaries, resulting in finer grain boundary precipitates and ultimately leading to a lower alloy strength. When the pre-aging temperature is 120 °C, the pre-aging process can reduce the vacancy concentration, thereby suppressing the phase transformation from η′ to η precipitates. For samples pre-aged to the η′ phase, solute atoms diffuse to the grain boundaries, resulting in grain boundary precipitates with a greater length during subsequent aging compared to the other two samples. These grain boundary precipitates exhibit a discontinuous distribution along the grain boundaries, which contributes to the improved elongation of the alloy. The present work provides a novel heat treatment strategy for producing high-strength Al alloys while effectively achieving a favorable balance between strength and ductility. Full article

(This article belongs to the Special Issue Multi-Principal Element Alloy Design and Surface Modification Technology)

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24 pages, 12119 KB

Open AccessArticle

Effect of HVOF Spraying Parameters on the Spraying Process and Particle Behavior of Amorphous Alloy Coatings

by Jianxing Yu, Zewei Dong, Yang Yu and Ruilong Gao

Coatings 2026, 16(2), 246; https://doi.org/10.3390/coatings16020246 - 14 Feb 2026

Viewed by 463

Abstract

High-velocity oxygen fuel (HVOF) spraying technology has been widely used to protect and repair the surface of mechanical parts and extend their service life. Spraying Fe-based amorphous alloy coatings can improve the corrosion resistance and fatigue resistance of the substrate. It is crucial [...] Read more.

High-velocity oxygen fuel (HVOF) spraying technology has been widely used to protect and repair the surface of mechanical parts and extend their service life. Spraying Fe-based amorphous alloy coatings can improve the corrosion resistance and fatigue resistance of the substrate. It is crucial to quantitatively elucidate the influence of process parameters on spraying behavior to achieve high-quality coatings. This study utilized a computational fluid-dynamics model to analyze the flight trajectories of flames and particles during HVOF spraying. Additionally, how parameters such as the O/F ratio, parallel barrel length, Laval nozzle diameter, and nitrogen flow rate affect flame and particle behavior was examined. These parameters were found to significantly impact the overall spraying process. As a result, the optimum structure and properties are obtained. In this study, the spray gun parameters were investigated to provide better guidance for the process and improve the quality and efficiency of the coating system. Full article

(This article belongs to the Special Issue Advances in Alloy Coatings: Tailored Performance for Modern Applications)

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21 pages, 4069 KB

Open AccessArticle

Insights into the Corrosion and Tribocorrosion Behaviors of DLC-Modified WC-Based Cermet Duplex Coatings

by Yingsen Wang, Zhenzhuang Liu and Yingpeng Zhang

Coatings 2026, 16(2), 245; https://doi.org/10.3390/coatings16020245 - 13 Feb 2026

Viewed by 440

Abstract

To gain deeper insight into the protective mechanism of tungsten carbide/diamond-like carbon (WC/DLC) duplex coatings, this study employed high-velocity oxygen-fuel (HVOF) combined with linear ion source (LIS) technology to deposit the WC/DLC duplex coating on the Ti₆Al₄V substrate. Their [...] Read more.

To gain deeper insight into the protective mechanism of tungsten carbide/diamond-like carbon (WC/DLC) duplex coatings, this study employed high-velocity oxygen-fuel (HVOF) combined with linear ion source (LIS) technology to deposit the WC/DLC duplex coating on the Ti₆Al₄V substrate. Their tribocorrosion behaviors were thoroughly investigated. The results show that the dense, uniform, and chemically inert DLC top layer acts as an effective barrier, preventing the corrosive medium from penetrating into the underlying WC cermet layer through pores. Consequently, the duplex coating exhibits a lower I_corr of 3.54 × 10⁻⁸ A/cm², compared with that of the single WC coating (1.08 × 10⁻⁶ A/cm²), demonstrating significantly improved corrosion resistance. Moreover, the DLC coating offers excellent tribological performance owing to the high hardness and self-lubricating characteristics. After depositing the DLC top layer on the HVOF-sprayed WC cermet, the COF is reduced to ~0.08, and the wear rate reaches only 5.64 × 10⁻⁸ mm³/N·m, indicating notably enhanced tribocorrosion resistance. In short, in such HVOF-PVD/CVD duplex coating systems, the PVD/CVD functional layer can improve the tribocorrosion performance of the HVOF interlayer by leveraging its intrinsic advantages, such as high hardness, low friction, dense and uniform microstructure, and chemical inertness. Full article

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

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16 pages, 10320 KB

Open AccessArticle

The Catalytic Effect of Rice Husk Ash on Pine Pyrolysis Based on a Three-Component System

by Xianning Liu, Xiaoyu Hu, Di Wu, Mengzhu Yu and Dengyu Chen

Coatings 2026, 16(2), 244; https://doi.org/10.3390/coatings16020244 - 13 Feb 2026

Viewed by 513

Abstract

Biomass is characterized by its diversity and wide availability. Co-pyrolysis technology is considered a promising approach for high-quality conversion and high-value utilization of biomass, representing a critical pathway toward environmental sustainability. This study selected rice husk and pine as representative herbaceous and woody [...] Read more.

Biomass is characterized by its diversity and wide availability. Co-pyrolysis technology is considered a promising approach for high-quality conversion and high-value utilization of biomass, representing a critical pathway toward environmental sustainability. This study selected rice husk and pine as representative herbaceous and woody biomass materials. Using a thermogravimetric analyzer (TGA) and Py-GC/MS, we systematically investigated the synergistic effects during co-pyrolysis, examined their underlying mechanisms, and analyzed changes in product distribution. The results indicate that the blend containing 30% rice husk exhibited the most pronounced synergistic effect. Specifically, the experimental char yield and pyrolysis activation energy were 9.7% and 10.5% lower than the theoretically calculated values, respectively. Both the blending ratio and heating rate were found to significantly influence these synergistic interactions. The observed synergy is attributed to the migration of alkali metals from rice husk ash, which enhances reaction rates and promotes specific pathways such as cellulose ring-opening cleavage and hemicellulose deacetylation. Consequently, the product distribution shifts toward lighter compounds, including aldehydes, ketones, and alcohols. This study clarifies the central catalytic role of herbaceous biomass ash and highlights the critical function of alkali metal migration in regulating product selectivity, thereby providing theoretical support for efficient pyrolytic conversion. Full article

(This article belongs to the Special Issue Multifunctional Thin Films from Hybrid Biopolymers and Nanomaterials)

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23 pages, 5171 KB

Open AccessFeature PaperArticle

Rational Design of Hollow Glass Microspheres/Urushiol Titanium Polymer–Zirconium Phosphate Coating System with Synergistic Anticorrosion Function for Waterborne Epoxy Resin

by Xiaoxiao Zheng, Runhui Mao, Mingmin Li, Jipeng Chen, Fengcai Lin, Donghui Wang, Guocai Zheng, Yanlian Xu and Qi Lin

Coatings 2026, 16(2), 243; https://doi.org/10.3390/coatings16020243 - 13 Feb 2026

Viewed by 659

Abstract

To tackle the long-standing issue of inadequate corrosion protection in waterborne coatings, this study innovatively incorporates hollow glass microspheres (HGB) into waterborne epoxy zinc-rich primers through physical blending, constructing a dual-layer synergistic anticorrosion system comprising an HGB-modified primer and a zirconium phosphate/urushiol titanium [...] Read more.

To tackle the long-standing issue of inadequate corrosion protection in waterborne coatings, this study innovatively incorporates hollow glass microspheres (HGB) into waterborne epoxy zinc-rich primers through physical blending, constructing a dual-layer synergistic anticorrosion system comprising an HGB-modified primer and a zirconium phosphate/urushiol titanium polymer (UTPCZrP)-modified waterborne epoxy topcoat. Optimal performance is achieved with 2 wt% HGB addition: the dual-layer coating retains favorable physicochemical and mechanical properties while enhancing anticorrosion performance by 1–2 orders of magnitude, boasting an impedance of 3.2 × 10⁶ Ω, a corrosion rate as low as 5.71 × 10^–6 mm/year, 99.98% protection efficiency (stable after 25-day immersion), and 720 h salt spray resistance without corrosion diffusion. This method exhibits universality in waterborne polyurethane (WPU) and polyester (WPE) systems, yielding impedance values of 3.57 × 10⁶ Ω and 2.7 × 10⁶ Ω, respectively, with over 90% improved anticorrosion performance and long-term stability. By optimizing components and synergistic system design, this work significantly enhances waterborne coatings’ anticorrosion efficiency, reduces raw material costs, and provides a scalable technical pathway for high-performance, eco-friendly anticorrosion coatings. Full article

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

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19 pages, 3707 KB

Open AccessArticle

PEI-Functionalized Surface Coating on Carbonized ZIF-8 for Enhanced Adsorption of Methyl Orange

by Zhenqiao Ma, Yuanyuan Xiong, Yiqing Deng, Peini Li, Xiandi Yang, Zhi Ye and Qiang Zhao

Coatings 2026, 16(2), 242; https://doi.org/10.3390/coatings16020242 - 13 Feb 2026

Viewed by 442

Abstract

The contamination of water resources by high concentrations of organic dyes poses severe threats to human health, making the removal of these pollutants critical. Metal–organic frameworks (MOFs) have shown promising potential in dye adsorption due to their high surface area and chemical stability. [...] Read more.

The contamination of water resources by high concentrations of organic dyes poses severe threats to human health, making the removal of these pollutants critical. Metal–organic frameworks (MOFs) have shown promising potential in dye adsorption due to their high surface area and chemical stability. Zeolitic imidazolate framework-8 (ZIF-8), a typical MOF, is known for its thermal stability and is frequently used in removing organic dyes. To enhance its adsorption performance, ZIF-8 is often carbonized to form porous carbon-based materials. However, carbonized ZIF-8 (CZ) often demonstrates restricted adsorption capacity and sluggish kinetics. To address these limitations, we chemically modified low-temperature carbonized ZIF-8 (CZ-550) with polyethyleneimine (PEI) using cyanuric chloride (CC) as a crosslinking agent, producing a novel composite (CZ@PEI/CC-7) featuring abundant amine-rich active sites for adsorption. This study evaluated the adsorption performance of CZ@PEI/CC-7 in removing methyl orange (MO) dye. Our findings reveal that CZ@PEI/CC-7 exhibits accelerated adsorption kinetics aligning with the pseudo-second-order kinetic model, while its isotherms fit the Freundlich and Temkin models, highlighting a favorable multilayer adsorption. Significantly, CZ@PEI/CC-7 achieved an adsorption capacity of 3150 mg/g for MO, compared to 1100 mg/g for unmodified CZ-550. Furthermore, the composite demonstrated excellent acid-base stability across a broad pH range (2–12), retaining structural integrity and adsorption efficiency. These findings suggest that CZ@PEI/CC-7 is a promising candidate for efficient MO removal from water. Full article

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

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22 pages, 1674 KB

Open AccessArticle

Packaging-Grade Paper Humidity Sensors Made by Flexography Only: From Sustainable Manufacturing to Transient Applications

by Tatiana Nowicka, Sandra Lepak-Kuc, Jerzy Szałapak, Daniel Janczak, Jarosław Szusta and Małgorzata Jakubowska

Coatings 2026, 16(2), 241; https://doi.org/10.3390/coatings16020241 - 13 Feb 2026

Viewed by 1320

Abstract

Printed electronics offer a scalable and sustainable route for integrating sensing systems into everyday environments; however, the use of flexography remains highly limited, and fully printed sensors fabricated exclusively with industrial flexographic technology have not been previously reported. This study evaluates the feasibility [...] Read more.

Printed electronics offer a scalable and sustainable route for integrating sensing systems into everyday environments; however, the use of flexography remains highly limited, and fully printed sensors fabricated exclusively with industrial flexographic technology have not been previously reported. This study evaluates the feasibility and practical limits of fabricating resistive humidity sensors for relative humidity (RH) measurements using flexography only, relying on commercial infrastructure, packaging-grade substrates, and low-temperature processing. Silver interdigitated electrodes and a carbon-based sensing layer were printed using solvent-based electronic inks, industrial aniloxes (12 and 20 cm³/m²), and standard flexographic conditions (10 m/min, ≤120 °C drying), without any post-processing. The sensing layer was optionally modified with adsorptive additives (≤5 wt% MgO; additionally, Al₂O₃ and Al) to enhance moisture interaction while maintaining rheological compatibility. Sensors were fabricated on recyclable paper substrates and PET for comparison. Under controlled conditions (10%–90% RH at 23 °C), devices exhibited a maximum relative resistance change of ~75% at 90% RH (referenced to 40% RH), low hysteresis (≤~5%), rapid visible response (<1 min), and stabilization within ~30 min. MgO increased relative response by 20%–233%, depending on humidity. Paper-based sensors showed higher responses but single-use behavior under flooding, while PET enabled repeatable cycling. Rather than targeting state-of-the-art performance, this work defines the functionality reliably achievable using flexography only, clarifying trade-offs among substrate choice, layer thickness, and additives for sustainable, humidity and disposable flood monitoring. Full article

(This article belongs to the Special Issue Advances in Surface and Coatings Technologies)

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13 pages, 2596 KB

Open AccessFeature PaperArticle

Enhancement of Corrosion Resistance in 304 Stainless Steel Through Hybrid Parylene C–ALD Al₂O₃ Composite Coatings

by Xuewei Xie, Woon-Ming Lau, Po-Wan Shum, Yongqiang Fu and Tao Fu

Coatings 2026, 16(2), 240; https://doi.org/10.3390/coatings16020240 - 13 Feb 2026

Viewed by 620

Abstract

Parylene C films are subjected to inadequate corrosion resistance due to their relatively low adhesion and structural defects. To address this challenge, the CVD Parylene C film (10 μm thick) was composited with Al₂O₃ film (30 nm thick) prepared with [...] Read more.

Parylene C films are subjected to inadequate corrosion resistance due to their relatively low adhesion and structural defects. To address this challenge, the CVD Parylene C film (10 μm thick) was composited with Al₂O₃ film (30 nm thick) prepared with atomic layer deposition (ALD) technology in this work. Optical microscopic results indicate uniform thickness of the films and the reduced adhesion of Parylene C based thick films. SEM-EDX and AFM results show that the composite films have more blurred mounds morphology than the individual films, and Al₂O₃ film decreases the surface roughness of Parylene C film; compared with the single-layer film, the R_a value of the bilayer film decreased by approximately 6%. XPS, FTIR and XRD analyses confirm the structural components of Al₂O₃ and Parylene C films and the annealing effect of ALD process on Parylene C film. Tafel polarization and electrochemical impedance spectroscopy tests reveal that the 304-Parylene C–Al₂O₃ system exhibits the optimal corrosion resistance; its corrosion current density (i_corr) is 8.099 × 10⁻⁵ μA/cm² and the ALD Al₂O₃ thin film uniformly coats the Parylene C film, enhancing its physical barrier and chemical passivation under corrosive conditions. Full article

(This article belongs to the Special Issue Advanced Corrosion- and Wear-Resistant Coatings)

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Coatings, Volume 16, Issue 2 (February 2026) – 123 articles

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