Coatings

17 pages, 2416 KiB

Open AccessArticle

Study on the Mechanism and Control Technology of Biodeterioration at the Sanyangzhuang Earthen Site

by Xiang Chang, Yu Ye, Qingwen Ma, Haitao Yan, Zhining Li and Fang Guo

Coatings 2025, 15(5), 617; https://doi.org/10.3390/coatings15050617 - 21 May 2025

Biodeterioration poses a significant challenge in the conservation of cultural heritage, particularly for earthen sites in humid environments, which are highly susceptible due to their inherent material properties. To address the diverse biological threats affecting such sites, we developed a novel broad-spectrum biocide, [...] Read more.

Biodeterioration poses a significant challenge in the conservation of cultural heritage, particularly for earthen sites in humid environments, which are highly susceptible due to their inherent material properties. To address the diverse biological threats affecting such sites, we developed a novel broad-spectrum biocide, FACA, formulated by combining phenylcarbamoylthiazoles and isothiaquinolones to achieve triple efficacy: antimicrobial, anti-algal, and anti-lichen effects. Laboratory assessments demonstrated FACA’s rapid efficacy in eliminating molds, algae, and lichens. A 12-month field application at the Sanyangzhuang earthen site (Neihuang, Henan) yielded excellent results, confirming long-term protection against biological colonization without recurrence. Crucially, the treatment exhibited no adverse effects on the earthen sites, enabling sustainable coexistence between the heritage site and its surrounding ecosystem. These findings support the applicability of FACA for surface treatment across various humid earthen archeological sites. Full article

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

17 pages, 7884 KiB

Open AccessArticle

The Effect of USRP-Composite DLC Coating on Bearing Fatigue Life

by Longtai Chen, Yanshuang Wang, Shuhui Xu, Mingyu Zhang and Guanghui Zheng

Coatings 2025, 15(5), 616; https://doi.org/10.3390/coatings15050616 - 21 May 2025

Abstract

Based on rolling contact fatigue life experiments, this study systematically investigates the effect of ultrasonic surface rolling processing (USRP) with a composite diamond-like carbon (DLC) coating on the rolling contact fatigue life of bearings through characterization and analysis. The results show that the [...] Read more.

Based on rolling contact fatigue life experiments, this study systematically investigates the effect of ultrasonic surface rolling processing (USRP) with a composite diamond-like carbon (DLC) coating on the rolling contact fatigue life of bearings through characterization and analysis. The results show that the USRP-composite DLC coating forms a synergistic mechanism between the coating and the substrate on the surface of specimens: the DLC coating resists surface wear with its high hardness and low friction coefficient, while USRP reduces substrate deformation and crack growth by decreasing surface roughness, increasing substrate hardness, and introducing residual compressive stress. Additionally, USRP enhances the adhesion between the coating and the substrate. The average wear volume of the USRP-composite DLC-coated specimens is 3.73 × 10¹¹ μm³, which is 30.95% lower than that of USRP-treated specimens and 85.38% lower than that of untreated specimens. The average fatigue life of the USRP-composite DLC-coated specimens is 6.55 × 10⁶ cycles, which is 94.94% higher than that of USRP-treated specimens and 208.24% higher than that of untreated specimens. Full article

(This article belongs to the Special Issue Surface Topography Measurement Analysis of Additively Manufactured Modern Materials and Coatings)

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11 pages, 3207 KiB

Open AccessArticle

Influence of the Surface Rolling Process on the Tribological and Electrical Behavior of T2 Copper Elastic Contact Pairs

by Zhenghai Yang, Mengfeng Zhao, Xiaowei Wang, Xiaojun Tian, Kaifeng Hu, Wenbo Li and Yongzhen Zhang

Coatings 2025, 15(5), 615; https://doi.org/10.3390/coatings15050615 - 21 May 2025

Abstract

Given the significant impact of the initial surface layer of materials on their tribological performance, this study uses a wire–plate reciprocating friction pair to investigate the effects of surface mechanical rolling process on the elastic current-carrying friction performance. The plate specimens were subjected [...] Read more.

Given the significant impact of the initial surface layer of materials on their tribological performance, this study uses a wire–plate reciprocating friction pair to investigate the effects of surface mechanical rolling process on the elastic current-carrying friction performance. The plate specimens were subjected to rolling processing with varying feed rates under different load conditions, using a self-designed current-carrying friction and wear testing machine. The results show that as the feed rate and load increase, the contact resistance varies within the range of 0.0065 Ω to 0.0310 Ω, with a standard deviation ranging from 0.01 Ω to 0.07 Ω, indicating good electrical conductivity. As the feed rate of the surface mechanical rolling increases, the wear rate of the material significantly decreases. Under all test conditions, the material wear marks exhibit plowing wear, and with the increase in surface mechanical rolling feed rate, the occurrence and intensification of adhesive wear are delayed. When the feed rate is 100 μm and the load is 0.025 N, the material wear rate is the lowest, reduced by 63.1% compared to the untreated condition. Full article

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

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23 pages, 7954 KiB

Open AccessArticle

A Comparative Study of the Effects of Superhydrophobic and Superhydrophilic Coatings on Dust Deposition Mitigation for Photovoltaic Module Surfaces

by Huaxu Tuo, Chuanxiao Zheng, Hao Lu, Yubo Liu, Chenyang Xu, Jiamin Cui and Yuhang Chen

Coatings 2025, 15(5), 614; https://doi.org/10.3390/coatings15050614 - 21 May 2025

Abstract

To comparatively evaluate the suitability of superhydrophobic and superhydrophilic coatings for photovoltaic (PV) module surfaces in arid and low-rainfall regions, this study investigates their dust deposition mitigation performance under anhydrous conditions and assesses the impact of dust reduction on PV power generation efficiency. [...] Read more.

To comparatively evaluate the suitability of superhydrophobic and superhydrophilic coatings for photovoltaic (PV) module surfaces in arid and low-rainfall regions, this study investigates their dust deposition mitigation performance under anhydrous conditions and assesses the impact of dust reduction on PV power generation efficiency. An experimental platform for dust deposition and a PV output measurement system were constructed to evaluate the performance of coated PV modules. The open-circuit voltage (U_oc), short-circuit current (I_sc), maximum power (P_max), and dust deposition mass were measured before and after dust exposure. Additionally, the influence of coating properties on dust deposition behavior and the correlation between dust deposition density and PV output power were systematically examined. The experimental data reveal a linear relationship between PV output power loss and dust deposition density. Dust accumulation decreases monotonically with panel tilt angle, while displaying a non-monotonic response to wind speed, peaking at 3.9 m/s. Under optimal conditions (60° tilt angle and 5.2 m/s wind speed), minimal dust deposition densities were observed: 0.25 g/m² for superhydrophobic coated PV modules versus 1.11 g/m² for superhydrophilic coated surfaces. Both superhydrophobic and superhydrophilic coatings demonstrated effective dust deposition inhibition in anhydrous environments. However, the dust deposition mitigation efficiency of the superhydrophobic coating (88.7%) is significantly better than that of the superhydrophilic coating (46.2%) under the working conditions of a large inclination angle (60°) and high wind speed (5.2 m/s). These findings provide critical experimental evidence for optimizing self-cleaning coating selection in PV modules deployed in arid regions. Full article

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

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17 pages, 3217 KiB

Open AccessArticle

Robust Adsorption of Pb(II) and Cd(II) by GLDA-Intercalated ZnAl-LDH: Structural Engineering, Mechanistic Insights, and Environmental Applications

by Kai Zheng, Zhengkai Guang, Zihan Wang, Yangu Liu, Xiaoling Cheng and Yuan Liu

Coatings 2025, 15(5), 613; https://doi.org/10.3390/coatings15050613 - 21 May 2025

Abstract

The rapid pace of industrialization has led to widespread heavy metal contamination in water and soil, highlighting the need for efficient remediation strategies. Among various approaches, adsorption has proven to be an effective method for treating contaminated environments. Layered double hydroxide (LDH) is [...] Read more.

The rapid pace of industrialization has led to widespread heavy metal contamination in water and soil, highlighting the need for efficient remediation strategies. Among various approaches, adsorption has proven to be an effective method for treating contaminated environments. Layered double hydroxide (LDH) is frequently used in such applications. However, its adsorption efficiency remains limited. In this study, glutamic acid diacetate tetrasodium salt (GLDA) was incorporated into ZnAl LDH via a straightforward co-precipitation and ion exchange method, yielding a modified material, GLDA-LDH, which was subsequently applied for the adsorption of Pb(II) and Cd(II). Adsorption behavior was investigated through kinetic and isothermal models, with results indicating that the process followed pseudo-second-order kinetics and fit well with the Langmuir isotherm, suggesting chemisorption onto monolayer surface. The maximum adsorption capacities reached 219.2 mg/g for Pb(II) and 121.9 mg/g for Cd(II). Furthermore, GLDA-LDH exhibited a strong retention capability for metal ions with minimal desorption and remained effective in the presence of hard water and contaminated soils. XPS analysis revealed distinct interaction mechanisms; surface oxygen and carboxyl groups played a key role in Pb(II) adsorption, whereas nitrogen coordination was involved in Cd(II) uptake. These results point to the potential of GLDA-LDH as a reliable material for addressing heavy metal pollution and provide insights into the design of enhanced LDH-based adsorbents. Full article

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

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12 pages, 2235 KiB

Open AccessArticle

The Influence of Anisotropic Microstructures on the Ice Adhesion Performance of Rubber Surfaces

by Fangyuan Zhang, Xiaosen Wang, Shilin Zhang, Xiaoqing Cao, Qiang He and Lu Li

Coatings 2025, 15(5), 612; https://doi.org/10.3390/coatings15050612 - 21 May 2025

Abstract

Anti-icing and de-icing technologies are crucial in modern aviation, with optimising ice adhesion performance on material surfaces being a key challenge. This study proposes a straightforward method for fabricating hydrophobic silicone rubber surfaces using a mesh to construct microstructures. The influence of microstructure [...] Read more.

Anti-icing and de-icing technologies are crucial in modern aviation, with optimising ice adhesion performance on material surfaces being a key challenge. This study proposes a straightforward method for fabricating hydrophobic silicone rubber surfaces using a mesh to construct microstructures. The influence of microstructure size and anisotropy on surface wettability and ice adhesion performance is systematically investigated. The experimental results demonstrate that introducing microstructures significantly enhances the hydrophobicity of silicone rubber surfaces, achieving a maximum static contact angle of 149.3 ± 1.3°. For microstructures with identical shapes, dimensional variations affect surface roughness and functional performance. Although the structure with the most significant dimension (600#-SR) exhibits the highest surface roughness, smaller structures (e.g., 1400#-SR) demonstrate superior hydrophobicity and lower ice adhesion strength, likely due to enhanced air entrapment and reduced effective solid–liquid and solid–ice contact areas. Furthermore, due to anisotropic microstructures, a marked directional difference in ice adhesion strength is observed: the lowest strength in the X direction is 38.6 kPa, compared to 63.3 kPa in the Y direction. Fine-tuning the size and configuration of microstructures effectively minimises the ice adhesion strength and enables targeted optimisation of surface properties. This research offers theoretical support for developing innovative, energy-efficient materials with superior anti-icing properties and provides new insights for crafting solutions tailored to various anti-icing needs. Full article

(This article belongs to the Special Issue Research Progress and Application of Super-hydrophobic Anti-icing Surface)

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30 pages, 10815 KiB

Open AccessReview

A Review of the Performance, Sustainable Applications, and Research Challenges of Limestone-Calcined Clay-Cement (LC3) Systems

by Jingjing Shao, Shun Guo and Haibo Wang

Coatings 2025, 15(5), 611; https://doi.org/10.3390/coatings15050611 - 21 May 2025

Abstract

This paper presents a systematic review of the progress of the research on limestone-calcined clay cement (LC3), focusing on its low-carbon characteristics, sustainable applications, and performance. LC3 can be used to address the high carbon emission problem in the cement industry, as its [...] Read more.

This paper presents a systematic review of the progress of the research on limestone-calcined clay cement (LC3), focusing on its low-carbon characteristics, sustainable applications, and performance. LC3 can be used to address the high carbon emission problem in the cement industry, as its use significantly reduces carbon dioxide emissions (by 30%–40%) due to clinker being partially replaced with calcined clay and limestone in its fabrication. Studies have shown that the hydration reaction of LC3 generates calcium-aluminum-silicate hydrate (C-A-S-H), carbon-aluminate, and calcium alumina, which optimize its microstructure and endow it with comparable mechanical properties (28 day compressive strength close to or exceeding that of OPC) and better durability (outstanding resistance to sulfate erosion and carbonation) compared to ordinary Portland cement (OPC). LC3 has been used in 3D printing, ocean engineering, geotechnical reinforcement, and other applications, all of which have verified its engineering feasibility. Despite the significant environmental and economic advantages of LC3, its high-temperature performance, freeze–thaw resistance, and long-term durability still need to be further investigated. This paper provides theoretical support and practical references for the development and promotion of low-carbon cement materials. Full article

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17 pages, 1888 KiB

Open AccessArticle

Effects of Coating Thickness and Aggregate Size on the Damping Properties of Concrete: A Numerical Simulation Approach

by Yisihak Gebre Tarekegn, Tom Lahmer, Abrham Gebre Tarekegn and Esayas Gebreyouhannes Ftwi

Coatings 2025, 15(5), 610; https://doi.org/10.3390/coatings15050610 - 21 May 2025

Abstract

Concrete properties are investigated using intensive physical testing processes that require large amounts of labor and materials that are costly and time-consuming. Properly validated computer models can replace most of the existing physical testing procedures with computer simulations that are relatively quick and [...] Read more.

Concrete properties are investigated using intensive physical testing processes that require large amounts of labor and materials that are costly and time-consuming. Properly validated computer models can replace most of the existing physical testing procedures with computer simulations that are relatively quick and inexpensive. Therefore, in this study, the effects of coating thickness and aggregate size on the damping properties of concrete were investigated using numerical simulation with Abaqus/CAE 6.14-1 software. Two different groups of aggregates were used in the simulation, with maximum aggregate sizes of 25 mm and 32 mm. The coating thickness ranged from 0.4 mm to 5.0 mm, using epoxy, silicone, and rubber coatings. The results showed that coatings with smaller aggregate size led to an increase in the damping ratio compared to those with larger aggregate size. Moreover, replacing 20% of coarse aggregates with rubber-coated aggregates results in a damping ratio of 5.75% to 6.21%, reflecting an increase of 22.8% to 32.7%. This variation occurs with coating thicknesses ranging from 0.4 mm to 5.0 mm, with the optimal thickness of 5.0 mm leading to the maximum increase (32.7%) in the damping ratio of concrete. Full article

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

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12 pages, 1708 KiB

Open AccessArticle

Research on Multi-Orbital Scanning Laser Bending Process of Polyvinyl Chloride Sheets

by Fuchao Kan, Haojie Xu, You Zhou, Kangmei Li and Jun Hu

Coatings 2025, 15(5), 609; https://doi.org/10.3390/coatings15050609 - 20 May 2025

Abstract

To make up for the lack of research on the laser bending process in the field of non-metals, this paper innovatively proposes a method to achieve controlled bending deformation of non-metallic components using laser processing of polyvinyl chloride (PVC) thin sheets. The main [...] Read more.

To make up for the lack of research on the laser bending process in the field of non-metals, this paper innovatively proposes a method to achieve controlled bending deformation of non-metallic components using laser processing of polyvinyl chloride (PVC) thin sheets. The main processing parameters affecting the deformation were analyzed by experimental comparison, and the multi-orbital laser application bending process was carried out with the illumination length and the thickness of the sheet as the variables, which revealed the deformation mechanism of PVC sheets under the laser effect. The surface morphology examinations of the exploration results were also compared to confirm the damage status of the objects. The bending mechanism was revealed by using the change in molecular chain status in the theory of polymer phase transition. This study proves the reliability of laser multi-orbital scanning of PVC sheets to achieve controlled bending deformation, providing a fundamental theoretical and experimental basis for the laser bending process of non-metallic components. Full article

(This article belongs to the Special Issue Laser Technology of Thin Film and Coatings)

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23 pages, 6820 KiB

Open AccessArticle

Anti-Erosion Mechanism of Biological Crusts and Eco-Protection Technology Using Composite Biofilms for Traditional Rammed Earth Dwellings in Songyang County

by Jiahui Yang, Ning Wang, Zebiao Huang, Yue Huang, Weilu Lv and Shuai Yang

Coatings 2025, 15(5), 608; https://doi.org/10.3390/coatings15050608 - 20 May 2025

Abstract

A typical county for traditional village conservation in China is Songyang County. It is renowned for its ancient rammed earth dwellings, which exhibit a unique microclimate and possess significant historical value. However, high precipitation and acid rain under the subtropical monsoon climate have [...] Read more.

A typical county for traditional village conservation in China is Songyang County. It is renowned for its ancient rammed earth dwellings, which exhibit a unique microclimate and possess significant historical value. However, high precipitation and acid rain under the subtropical monsoon climate have caused severe surface erosion, including cracking and spalling. This study focuses on traditional rammed earth dwellings in Chenjiapeng Village, Songyang County, combining field surveys, experimental analysis, and microscopic characterization to systematically investigate erosion mechanisms and protection strategies. Techniques, such as drone aerial photography, X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and microbial diversity detection, were employed to elucidate the anti-erosion mechanisms of gray–green biological crusts on rammed earth surfaces. The results indicate that algal crusts enhance surface compressive strength and shear resistance through macroscopic coverage (reducing raindrop kinetic energy and moisture retention) and microscopic extracellular polysaccharide-cemented soil particles forming a three-dimensional network. However, acidic environments induce metabolic acid release from algae, dissolving cementing materials and creating a “surface protection-internal damage” paradox. To address this, a “transparent film-biofiber-acid inhibition layer” composite biofilm design is proposed, integrating a biodegradable polylactic acid (PLA) mesh, algal attachment substrates, and calcium carbonate microparticles to dynamically neutralize acidic substances, achieving synergistic ecological protection and cultural heritage authenticity. This study provides innovative solutions for the anti-erosion protection of traditional rammed earth structures, emphasizing environmental compatibility and sustainability. Full article

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

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20 pages, 3018 KiB

Open AccessArticle

Performance Evaluation of Desulfurized Rubber Powder and Styrene-Butadiene-Styrene Composite-Modified Asphalt

by Bin Liu, Kai Zhang, Xiangyang Fan and Chongzhi Tu

Coatings 2025, 15(5), 607; https://doi.org/10.3390/coatings15050607 - 19 May 2025

Abstract

Rubber powder asphalt has been widely studied due to its favorable temperature sensitivity and fatigue resistance. However, because rubber powder does not easily swell in asphalt, it leads to poor storage stability and high viscosity, limiting its large-scale application. In this study, modified [...] Read more.

Rubber powder asphalt has been widely studied due to its favorable temperature sensitivity and fatigue resistance. However, because rubber powder does not easily swell in asphalt, it leads to poor storage stability and high viscosity, limiting its large-scale application. In this study, modified asphalt was prepared using desulfurized rubber powder (DRP) and styrene-butadiene-styrene (SBS) modifiers, aiming to identify the optimal formulation for enhanced performance. It was hypothesized that the combined use of DRP and SBS would produce synergistic effects, improving the overall mechanical and rheological properties of the asphalt. To test this, the effects of this composite modification were evaluated using Marshall tests (penetration, softening point, ductility, elastic recovery, and Brookfield viscosity) and Superpave tests (shear modulus, high-performance grade, rutting factor, fatigue factor, and creep and recovery). Additionally, moisture susceptibility, high-temperature stability, low-temperature cracking resistance, and fatigue resistance at the mixture level were assessed. Performance was evaluated according to the Chinese standard JT/T 798-2019 for rubberized asphalt using reclaimed tire rubber. Results show that DRP-modified asphalt demonstrates excellent temperature sensitivity, rutting resistance, deformation resistance, and fatigue performance. However, an excessive amount of DRP increases Brookfield viscosity, which negatively affects the workability of the asphalt binder. The addition of SBS further improves the softening point, ductility, and deformation recovery of the binder. Considering cost-effectiveness and overall performance, the optimal formulation was determined to be 25% DRP and 1% SBS. At this dosage, all performance indicators met the required standards. The rotational viscosity at 180 °C was approximately 35% lower than that of conventional rubber powder–modified asphalt, while the high-temperature rutting factor and fatigue resistance at medium-to-low temperatures outperformed those of SBS-modified asphalt. The mixture test results reveal that the gradation has an impact on the performance of the obtained mixture, but overall, the DRP-SBS composite-modified asphalt mixture has significant advantages in terms of performance and cost-effectiveness. Full article

(This article belongs to the Special Issue Advances in Asphalt and Concrete Coatings)

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15 pages, 4939 KiB

Open AccessArticle

Icing and Adhesive Characteristics of Iced Airfoils Under Rime Ice Conditions

by Weihan Shi, Sicheng Shen, Guoan Hou, Juan Ding, Wenfeng Guo and Yingwei Zhang

Coatings 2025, 15(5), 606; https://doi.org/10.3390/coatings15050606 - 19 May 2025

Viewed by 25

Abstract

Airfoils are widely used in the fields of aviation and wind power generation. Icing changes the profile of an airfoil and degrades its aerodynamic performance. Therefore, it is necessary to explore the icing of airfoils and the adhesive characteristics of the ice formed [...] Read more.

Airfoils are widely used in the fields of aviation and wind power generation. Icing changes the profile of an airfoil and degrades its aerodynamic performance. Therefore, it is necessary to explore the icing of airfoils and the adhesive characteristics of the ice formed in order to explore their de-icing. In the present study, this is accomplished for the NACA0018 and S809 airfoils through measurement of the areas, thicknesses, and adhesive strength of the ice formed under different wind speeds. The iced area increased linearly with the icing time. The area on the S809 airfoil covered with ice was larger than that on the NACA0018 airfoil because of the maximum thickness of the airfoil profile, the distribution of surface pressures, and the flow state of the air. The effects of wind speed on the adhesive strengths of the ice formed on both airfoils were then explored. The adhesive strength of ice on the NACA0018 airfoil increased with the wind speed, while the wind speed had a minor effect on the ice on the S809 airfoil. These findings provide a foundation for the in-depth exploration of de-icing technology. Full article

(This article belongs to the Special Issue Research Progress and Application of Super-hydrophobic Anti-icing Surface)

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8 pages, 536 KiB

Open AccessCommunication

Fano Resonance in Ion-Bombarded Au-SiO₂ Nanocomposites: Analysis of Mode Coupling and Optical Properties

by Padmaja Guggilla, Sharvare Palwai, Angela Davis, Jonathan Lassiter, Satilmis Budak and Clyde Varner

Coatings 2025, 15(5), 605; https://doi.org/10.3390/coatings15050605 - 19 May 2025

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Abstract

This study investigates the optical properties of ion-bombarded Au-SiO₂ nanocomposites, focusing on the enhanced Fano resonance observed in these samples. The formation of nanocrystals and nanocavities due to ion bombardment leads to significant interactions between plasmonic and vibrational modes, resulting in pronounced [...] Read more.

This study investigates the optical properties of ion-bombarded Au-SiO₂ nanocomposites, focusing on the enhanced Fano resonance observed in these samples. The formation of nanocrystals and nanocavities due to ion bombardment leads to significant interactions between plasmonic and vibrational modes, resulting in pronounced Fano resonance in the strong coupling regime. The study aims to explain the closer spacing of modes, the elevated baseline absorbance, and the asymmetric lineshape observed in the ion-bombarded samples. A detailed analysis is provided, comparing these findings with other sample preparations, such as Au-coated SiO₂ and 20 nm Au colloidal on SiO₂. The implications of these results for understanding plasmonic behavior and their potential applications in nanophotonics are discussed. Full article

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16 pages, 3096 KiB

Open AccessArticle

Effect of Desulfurization Ash Content on the Low-Temperature Rheological Properties of Asphalt Mastic

by Yinghui Zhang, Kai Li, Yong Wu and Zhigang Zhou

Coatings 2025, 15(5), 604; https://doi.org/10.3390/coatings15050604 - 18 May 2025

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Abstract

Circulating fluidized bed combustion flue gas desulfurization generates large volumes of dry desulfurization ash requiring sustainable management. This study evaluated the impacts of substituting desulfurization ash for mineral powder filler in asphalt mastic on low-temperature rheological properties. Asphalt mastics were produced with 0–100% [...] Read more.

Circulating fluidized bed combustion flue gas desulfurization generates large volumes of dry desulfurization ash requiring sustainable management. This study evaluated the impacts of substituting desulfurization ash for mineral powder filler in asphalt mastic on low-temperature rheological properties. Asphalt mastics were produced with 0–100% ash replacing mineral powder at 0.8–1.2 powder-binder mass ratios. Ductility and bending beam rheometer testing assessed flexibility and crack resistance. Burgers’ model fitted bending creep compliance to derive relaxation time, m(t)/S(t) index, and low-temperature compliance parameter for analytical insight. Scanning electron microscopy and Fourier transform infrared spectroscopy probed microstructural development and interaction mechanisms. Results showed that the inclusion of desulfurization ash reduced the low-temperature performance of the asphalt mastic compared to the mineral powder asphalt mastic. Additionally, as the temperature decreased further, the effect of the powder-to-gum ratio on the slurry’s crack resistance became less pronounced. Desulfurization ash primarily interacted with the base bitumen through physical means, and the performance of desulfurization ash asphalt slurry mainly depended on the degree of swelling between the desulfurization ash and the base asphalt. Full article

(This article belongs to the Special Issue Novel Cleaner Materials for Pavements)

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14 pages, 4067 KiB

Open AccessArticle

Thin Films of PNDI(2HD)2T and PCPDTBT Polymers Deposited Using the Spin Coater Technique for Use in Solar Cells

by Michał Sładek, Patryk Radek, Magdalena Monika Szindler and Marek Szindler

Coatings 2025, 15(5), 603; https://doi.org/10.3390/coatings15050603 - 18 May 2025

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Abstract

Conductive polymers play a crucial role in the advancement of modern technologies, particularly in the field of organic photovoltaics (OPVs). Due to advantages such as flexibility, low specific weight, ease of processing, and low production costs, polymeric materials present an attractive alternative to [...] Read more.

Conductive polymers play a crucial role in the advancement of modern technologies, particularly in the field of organic photovoltaics (OPVs). Due to advantages such as flexibility, low specific weight, ease of processing, and low production costs, polymeric materials present an attractive alternative to traditional photovoltaic materials. This study investigates the properties of a polymer blend composed of PCPDTBT (donor) and PNDI(2HD)2T (acceptor), used as the active layer in bulk heterojunction (BHJ) solar cells. The motivation behind this research was the search for a novel n-type polymer material with potentially better properties than the commonly used P(NDI2OD-T2). Comprehensive characterization of thin films made from the individual polymers and their blend was conducted using Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Ultraviolet-Visible Spectroscopy (UV-Vis), four-point probe conductivity measurements, and photovoltaic testing. The prepared films were continuous, uniform, and exhibited low surface roughness (R_a < 2.5 nm). Spectroscopic analysis showed that the blend absorbs light in a broad range of the spectrum, with slight bathochromic shifts compared to individual polymers. Electrical measurements indicated that the blend’s conductivity (9.1 µS/cm) was lower than that of pure PCPDTBT but higher than that of PNDI(2HD)2T, with an optical band gap of 1.34 eV. Photovoltaic devices fabricated using the blend demonstrated an average power conversion efficiency (PCE) of 6.45%, with a short-circuit current of 14.37 mA/cm² and an open-circuit voltage of 0.89 V. These results confirm the feasibility of using PCPDTBT:PNDI(2HD)2T blends as active layers in BHJ solar cells and provide a promising direction for further optimization in terms of polymer ratio and processing conditions. Full article

(This article belongs to the Special Issue Recent Developments in Thin Films for Technological Applications)

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16 pages, 20780 KiB

Open AccessArticle

Effect of Si on Mechanical Properties and Oxide Film Formation of AFA Alloy at Low Oxygen Pressure

by Qijun Jia, Xiaoqiang Jiang, Changjun Wu, Junxiu Chen, Xiangying Zhu, Ya Liu and Xuping Su

Coatings 2025, 15(5), 602; https://doi.org/10.3390/coatings15050602 - 18 May 2025

Viewed by 167

Abstract

The Cr₂O₃ film on the outer surface of traditional cracking furnace tubes is prone to spalling, which shortens the tube life. Fe-Ni-Cr-based austenitic stainless steel (AFA alloy) with added Al has attracted attention because it can form a more stable [...] Read more.

The Cr₂O₃ film on the outer surface of traditional cracking furnace tubes is prone to spalling, which shortens the tube life. Fe-Ni-Cr-based austenitic stainless steel (AFA alloy) with added Al has attracted attention because it can form a more stable Al₂O₃ film on the surface. However, the alloy’s mechanical performance and the stability and oxidation resistance of the oxide film need to be improved simultaneously. This investigation examined silicon concentration variations (0–1.5 wt.%) on AFA alloy’s ambient-temperature tensile performance and oxidation response under reduced oxygen partial pressures (10⁻¹⁸–10⁻¹⁶ bar). The findings demonstrate that the alloy was composed of the FCC, B2-NiAl, and M₂₃C₆ phases. With Si addition, the B2-NiAl phase volume fraction increased. Mechanical testing demonstrated progressive elevation in tensile strength and hardness coupled with reduced elongation, attributable to combined solid-solution hardening and B2-NiAl precipitation strengthening. At low oxygen pressure, a continuous multi-layer oxide film developed on the alloy’s surface: the outermost layer was composed of a continuous Cr₂O₃ layer, with a fraction of MnCr₂O₄ spinel phase enriched on the outer surface. The middle layer was SiO₂, which evolved from a particulate to a continuous layer with increasing Si content. The innermost layer was composed of Al₂O₃. Accelerated manganese diffusion through Cr₂O₃ facilitated MnCr₂O₄ spinel layer formation. Full article

(This article belongs to the Collection Feature Paper Collection for Topic Editors and Invited Scholars in Coatings)

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9 pages, 1798 KiB

Open AccessArticle

Magnetoplasmonic Resonators Designed with Hexagonally Arrayed Au/BIG Bilayer Nanodisks on Au Thin Film Layers for Enhanced MOKE and Refractive Index Sensing

by Ziqi Wang, Xiaojian Cui and Yujun Song

Coatings 2025, 15(5), 601; https://doi.org/10.3390/coatings15050601 - 18 May 2025

Viewed by 92

Abstract

A kind of magnetoplasmonic resonators is numerically designed with hexagonally arrayed Au/bismuth iron garnet (BIG) bilayer nanodiscks on Au thin film layers. Multi-physics coupling calculation on their magnetoplasmonic resonance features suggest that there exists a strong resonant coupling between the surface plasmon excited [...] Read more.

A kind of magnetoplasmonic resonators is numerically designed with hexagonally arrayed Au/bismuth iron garnet (BIG) bilayer nanodiscks on Au thin film layers. Multi-physics coupling calculation on their magnetoplasmonic resonance features suggest that there exists a strong resonant coupling between the surface plasmon excited by the hexagonal grating and the waveguide modes induced by Au-BIG-Au, which can significantly enhance the transverse magneto-optical Kerr effect. Interestingly, a new type of circular oscillating can be induced in the optical-transparent BIG layers as the thickness of BIG layers is between 2 nm and 22 nm. This circular oscillating exhibits a distinct thickness-dependent feature, which can be attributed to the near field interference of the excited localized plasmon resonance between the two interfaces formed by the middle BIG nanodiscs in the top Au nanodisks and the bottom Au thin film layers according to the simulation. These unique magnetoplasmonic features endow this kind of magnetoplasmonic resonators with a greatly enhanced refractive index sensing property, with a calculated figure of merit (FOM) value of up to 7527 RIU⁻¹. Full article

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11 pages, 9609 KiB

Open AccessArticle

Research on the Influence of Laser Cleaning Parameters on the Removal Effectiveness of Al Metal Layers from Ceramic Substrate Surfaces

by Yuqin Li, Hangchao Wang, Weizhuo Hua, Hang Wang and Yuchang Qing

Coatings 2025, 15(5), 600; https://doi.org/10.3390/coatings15050600 - 18 May 2025

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Abstract

This study explores a novel method for removing Al metal coatings by using nanosecond pulsed lasers to clean Al metal layers from ceramic substrate surfaces. The impact of laser power and pulse width on the effectiveness of the removal of the Al metal [...] Read more.

This study explores a novel method for removing Al metal coatings by using nanosecond pulsed lasers to clean Al metal layers from ceramic substrate surfaces. The impact of laser power and pulse width on the effectiveness of the removal of the Al metal layer from the ceramic substrate was examined. The findings revealed that a laser with a power of 120 W, a pulse width of 200 ns, a frequency of 240 kHz, and a speed of 6000 mm/s could effectively remove the Al metal layer (50 μm) in a single laser cleaning cycle without causing damage to the ceramic substrate. The mechanism behind the removal of the Al metal layer from the ceramic substrate surface was also investigated. It was discovered that local high temperatures caused by laser irradiation and the difference in thermal expansion coefficients between the metal layer and the ceramic substrate both contribute to the removal of the Al metal layer during the laser cleaning process. This research provides an effective process for removing the Al metal layer. Full article

(This article belongs to the Special Issue Advanced Coating Material for Heritage Preservation, 2nd Edition)

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36 pages, 9564 KiB

Open AccessReview

Research Progress of the Coatings Fabricated onto Titanium and/or Titanium Alloy Surfaces in Biomaterials for Medical Applications for Anticorrosive Applications

by Qin Rao, Jinshuang Zhang, Yaqing Chen, Yujin Yang, Xu Chen, Donghao Liu, Ruilu Zhu, Ang Li, Yanping Lv and Shunli Zheng

Coatings 2025, 15(5), 599; https://doi.org/10.3390/coatings15050599 - 17 May 2025

Viewed by 139

Abstract

Titanium (Ti) and its alloys have attracted more interest, as they are widely employed as biomaterials due to their great biocompatibility, excellent strength ratio, and lightweight. However, corrosion occurs slowly due to an electrochemical reaction once the Ti material has been placed in [...] Read more.

Titanium (Ti) and its alloys have attracted more interest, as they are widely employed as biomaterials due to their great biocompatibility, excellent strength ratio, and lightweight. However, corrosion occurs slowly due to an electrochemical reaction once the Ti material has been placed in the human body, contributing to infection and failure of implants in medical applications. Thus, the corrosion phenomenon has caused great concern in the biomedical field. It is desirable to make the surface modification to provide better corrosion resistance. The fabrication techniques of the coatings fabricated onto Ti and/or Ti alloy surfaces have been reported, including sol–gel, annealing, plasma spraying, plasma immersion ion implantation, physical vapor deposition, chemical vapor deposition, anodization, and micro-arc oxidation. This review first describes the corrosion types, including localized corrosion (both pitting and crevice corrosion), galvanic corrosion, selective leaching, stress corrosion cracking (SCC), corrosion fatigue (CF), and fretting corrosion. In the second part, the effects of corrosion on the human body were discussed, and the primary cause for clinical failure and allergies has been identified as the excessive release of poisonous and dangerous metal ions (Co, Ni, and Ti) from corroded implants into bodily fluids. The inclusion and exclusion criteria during the selection of literature are described in the third section. In the last section, we emphasized the current research progress of Ti alloy (particularly Ti6Al4V alloy) coatings in biomaterials for medical applications involving dental, orthopedic, and cardiovascular implants for anticorrosive applications. However, there are also several problems to explore and address in future studies, such as the release of excessive metal ions, etc. This review will draw attention to both researchers and clinicians, which could help to increase the coatings fabricated onto Ti and/or Ti alloy surfaces for anticorrosive applications in biomaterials for medical applications. Full article

(This article belongs to the Special Issue Innovative Coatings for Corrosion Protection of Alloy Surfaces)

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14 pages, 3946 KiB

Open AccessArticle

Effect of TiC Addition on Microstructure and Performances of Double Pulse Electrodeposited Ni-TiC Coatings

by Haijun Liu, Hui Wang and Fafeng Xia

Coatings 2025, 15(5), 598; https://doi.org/10.3390/coatings15050598 - 17 May 2025

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Abstract

Nickel–titanium carbide (Ni-TiC) coatings were synthesized on Q235 steel via double-pulse electrodeposition to enhance surface properties. The influence of TiC concentration on surface morphology, microstructure, and performance was systematically studied using SEM, TEM, XRD, microhardness testing, wear analysis, and electrochemical methods. At low [...] Read more.

Nickel–titanium carbide (Ni-TiC) coatings were synthesized on Q235 steel via double-pulse electrodeposition to enhance surface properties. The influence of TiC concentration on surface morphology, microstructure, and performance was systematically studied using SEM, TEM, XRD, microhardness testing, wear analysis, and electrochemical methods. At low TiC concentrations (2–4 g/L), the coatings exhibited typical cell-like morphology. At 8 g/L, the coating showed a dense structure, refined grains, and broad Ni diffraction peaks. TEM analysis revealed nickel and TiC grain sizes of 97.82 nm and 34.75 nm, respectively. The plating rate remained stable (~36.94 mg·cm⁻²·h⁻¹), while surface roughness increased with TiC content. The 8 g/L TiC coating achieved the highest microhardness (743.13 HV), lowest wear loss (5.43%), and superior corrosion resistance, with a self-corrosion current density of 5.27 × 10⁻⁶ A·cm⁻² and polarization resistance of 7705.62 Ω·cm². These enhancements are attributed to uniform TiC dispersion and grain boundary pinning. Thus, 8 g/L TiC is optimal for fabricating Ni-TiC coatings with improved mechanical and electrochemical performance. This work demonstrates a practical strategy for developing high-performance Ni-based composite coatings via double-pulse electrodeposition. Full article

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31 pages, 823 KiB

Open AccessReview

Traditional and Recent Alternatives for Controlling Bacterial Foodborne Pathogens in Fresh Horticultural Commodities—A Review

by Silvia Bautista-Baños, Zormy Nacary Correa-Pacheco, Rosa Isela Ventura-Aguilar, Patricia Landa-Salgado, Mónica Cortés-Higareda and Margarita de Lorena Ramos-García

Coatings 2025, 15(5), 597; https://doi.org/10.3390/coatings15050597 - 17 May 2025

Viewed by 245

Abstract

Fresh horticultural products have proven to be an excellent source of minerals, vitamins, and functional compounds for human consumption, resulting in horticultural production evolving from a local to a worldwide condition. However, during their commercialization, there can be side effects, such as the [...] Read more.

Fresh horticultural products have proven to be an excellent source of minerals, vitamins, and functional compounds for human consumption, resulting in horticultural production evolving from a local to a worldwide condition. However, during their commercialization, there can be side effects, such as the risk of contamination of foodborne illness outbreaks caused largely by bacterial microorganisms. To reduce their incidence, there exist conventional strategies that include mainly chemical and physical methods. Some of them have already been adopted by the horticultural food industry, while others are still under investigation, such as biological control. In recent years, research about the development and application of coatings has increased. There is a growing trend to design and evaluate active formulations based on naturally and non-toxic occurring compounds with antimicrobial effects against foodborne pathogens including, among others, essential oils, plant extracts, organic acids, and chitosan. Furthermore, nanomaterial-based formulations have also been recently tested, resulting in excellent materials to control them. Nevertheless, it is paramount to assess the safety and risk of these materials associated with human consumption. In this review, the current situation of foodborne pathogens in fruit and vegetables, the traditional control methods, and the future development of coating formulations with new materials are reviewed. In addition, the overall action mechanisms of the antimicrobial coating components were briefly described. Full article

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

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17 pages, 3659 KiB

Open AccessArticle

Tribological Performance of TiN–WS₂ Soft–Hard Multifunctional Composite Coatings Deposited by Magnetron Sputtering

by Hu Qiao, Shengchao Zhu, Suixin Fan, Jiawei Kang, Peichao Tian, Jianxin Yang and Youqing Wang

Coatings 2025, 15(5), 596; https://doi.org/10.3390/coatings15050596 - 17 May 2025

Viewed by 157

Abstract

Titanium nitride (TiN) is a widely used industrial hard coating material, known for its excellent hardness and chemical stability. However, its relatively high coefficient of friction (COF) often leads to interfacial heat accumulation and adhesive wear during service, limiting its applicability in high-temperature [...] Read more.

Titanium nitride (TiN) is a widely used industrial hard coating material, known for its excellent hardness and chemical stability. However, its relatively high coefficient of friction (COF) often leads to interfacial heat accumulation and adhesive wear during service, limiting its applicability in high-temperature tribological environments. To enhance its tribological performance, a TiN–WS₂ soft–hard composite coating was fabricated on cemented carbide substrates using reactive co-sputtering magnetron deposition. By adjusting the sputtering parameters and target power ratio, a synergistic deposition of the hard (TiN) and lubricating (WS₂) phases was achieved and compared with a pure TiN coating. The results revealed that the incorporation of WS₂ significantly reduced the COF at both room temperature (25 °C) and an elevated temperature (200 °C), with the average values decreasing from 0.61 to 0.39 at 25 °C and from 0.53 to 0.36 at 200 °C. A white light interferometry analysis showed that the TiN–WS₂ coating exhibited narrower wear tracks and less surface damage than TiN at elevated temperatures, demonstrating superior friction-reducing and wear-resistant capabilities. In terms of mechanical properties, the composite coating showed a reduction in the hardness, the reduced elastic modulus (Er), and the adhesion strength by 27.3%, 19.8%, and 9.5%, respectively, compared to pure TiN. These findings indicate that the introduction of a quantitatively controlled lubricating WS₂ phase allows for a balance between nanoscale hardness and wear resistance, offering promising potential for engineering applications under complex working conditions. Full article

(This article belongs to the Special Issue Innovative Surface Treatment Technologies for Enhanced Coating Performance)

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16 pages, 4581 KiB

Open AccessArticle

PLA-Based Green Antimicrobial and Flame-Retardant Biocomposites Reinforced with Sida hermaphrodita Fibers

by Sandra Bischof, Tea Bušac, Tomislav Ivanković, Sabine Rolland du Roscoat, Bratislav Lukic and Zorana Kovačević

Coatings 2025, 15(5), 595; https://doi.org/10.3390/coatings15050595 - 17 May 2025

Viewed by 152

Abstract

Enhanced demand for the development of sustainable materials has generated significant research interest in products containing biomass-derived fibers, such as the fibers extracted from the energy crop Sida hermaphrodita (SH). Green chemicals and green methods, such as microwave treatment, have been used for [...] Read more.

Enhanced demand for the development of sustainable materials has generated significant research interest in products containing biomass-derived fibers, such as the fibers extracted from the energy crop Sida hermaphrodita (SH). Green chemicals and green methods, such as microwave treatment, have been used for the isolation of fibers from biomass waste. In this study, long extracted fibers were used as a reinforcement of the PLA matrix to give them high strength, which is required for high-performance biocomposites. To enable composite usage in automotive industry, several additives were applied to enhance their mechanical, thermal, and antimicrobial properties. Therefore, vegetable drying oil, montmorillonite nanoclay (MMT), and milled cork were used to improve their mechanical and thermal properties. Zinc oxide (ZnO) was applied to enhance the biocomposite’s antimicrobial properties, which were confirmed through significant bacterial reduction across all tested biocomposite variants, particularly in samples functionalized with ZnO, cork, and montmorillonite. Additionally, X-ray microtomography provided detailed insight into fiber dispersion and internal structural heterogeneity, which is crucial for evaluating mechanical performance and flame-retardant behavior. All characterization methods, including mechanical ones, lead to the conclusion that green and sustainable biocomposites based on PLA and Sida hermaphrodita fibers treated with antimicrobial (AM) and flame-retardant (FR) agents can be successfully applied for a wide variety of antimicrobial and flame-retardant products. Full article

(This article belongs to the Special Issue Engineered Coatings for a Sustainable Future)

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10 pages, 2206 KiB

Open AccessArticle

Experimental Investigation of Lubrication Performance of Rhombic-Textured TiN-Coated Surfaces Under Lubricated Conditions

by Juan Chen, Jie Zhou, Binbin Ji, Liangcai Zeng, Yang Mao and Jun Wei

Coatings 2025, 15(5), 594; https://doi.org/10.3390/coatings15050594 - 17 May 2025

Viewed by 154

Abstract

Surface texture and titanium nitride (TiN) coating have been established as effective methods for enhancing the tribological properties of mechanical friction pairs. This work aims to investigate the lubrication performance of rhombic-textured TiN-coated surfaces under oil-lubricated conditions using a pin-on-disk test mode. A [...] Read more.

Surface texture and titanium nitride (TiN) coating have been established as effective methods for enhancing the tribological properties of mechanical friction pairs. This work aims to investigate the lubrication performance of rhombic-textured TiN-coated surfaces under oil-lubricated conditions using a pin-on-disk test mode. A total of 17 sets of samples were designed, including a control sample (with no rhombic texture and no TiN coating), a TiN-coated sample and rhombic-textured TiN-coated samples. The rhombic surface texture was fabricated using the end surface of a brass bar. TiN coating deposited TiN on the textured surface. This study focuses on measuring and comparatively analyzing the lubrication load capacity, friction coefficient (COF) and binding force of TiN coatings/substrates in the pin-on-disk friction test mode. Compared with the bare control sample, a rhombic texture can enhance lubrication load-carrying capacity by generating hydrodynamic lubrication effects, thereby reducing friction. Additionally, a rhombic texture enables the mitigation of third-body wear due to wear debris. This research provides valuable insights into the design and fabrication of mechanical friction pairs with high wear resistance under oil-lubricated conditions. For lubrication property enhancement, the influence of groove depth was larger than that of the length of the rhombic side. Full article

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17 pages, 7701 KiB

Open AccessArticle

Magnetite-Modified Asphalt Pavements in Wireless Power Transfer: Enhancing Efficiency and Minimizing Power Loss Through Material Optimization

by Xin Cui, Aimin Sha, Liqun Hu and Zhuangzhuang Liu

Coatings 2025, 15(5), 593; https://doi.org/10.3390/coatings15050593 - 16 May 2025

Viewed by 71

Abstract

Wireless power transfer (WPT) is recognized as a critical technology to advance carbon neutrality in transportation by alleviating charging challenges for electric vehicles and accelerating their adoption to replace fossil fuel. To ensure durability under traffic loads and harsh environments while avoiding vehicle [...] Read more.

Wireless power transfer (WPT) is recognized as a critical technology to advance carbon neutrality in transportation by alleviating charging challenges for electric vehicles and accelerating their adoption to replace fossil fuel. To ensure durability under traffic loads and harsh environments while avoiding vehicle obstructions, WPT primary circuits should be embedded within pavement structures rather than surface-mounted. This study systematically investigated the optimization of magnetite-modified asphalt material composition and thickness for enhancing electromagnetic coupling in WPT systems through integrated numerical and experimental approaches. A 3D finite element model (FEM) and a WPT platform with primary-side inductor–capacitor–capacitor (LCC) and secondary-side series (S) compensation were developed to assess the electromagnetic performance of magnetite content ranging from 0 to 25% and pavement thickness ranging from 30 to 70 mm. Results indicate that magnetite incorporation increased efficiency from 80.3 to 84.7% and coupling coefficients from 0.236 to 0.242, with power loss increasing by only 0.25 W. This enhancement is driven by improved equivalent permeability, which directly enhances magnetic coupling efficiency. A critical pavement thickness of 50 mm was identified, beyond which the reduction in transmission efficiency increased significantly due to magnetic flux dispersion. Additionally, the nonlinear increase in power loss is partially attributed to the significant rise in hysteresis and eddy current losses at elevated magnetite content levels. The proposed design framework, which focuses on 10% magnetite content and a total pavement thickness of 50 mm, achieves an optimal energy transfer efficiency. This approach contributes to sustainable infrastructure development for wireless charging applications. Full article

(This article belongs to the Special Issue Synthesis and Application of Functional Polymer Coatings)

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31 pages, 2749 KiB

Open AccessReview

Modern Innovations and Applications in Plasma Electrolytic Oxidation Coatings on Aluminum, Magnesium, and Titanium

by Angus G. McCarroll and Pradeep L. Menezes

Coatings 2025, 15(5), 592; https://doi.org/10.3390/coatings15050592 - 16 May 2025

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Abstract

Plasma electrolytic oxidation (PEO) is an electrochemical surface modification technique for producing dense oxide layers on valve metals. This review compiles the various modifications to the PEO process that have been used to improve the produced coatings and make them suitable for specific [...] Read more.

Plasma electrolytic oxidation (PEO) is an electrochemical surface modification technique for producing dense oxide layers on valve metals. This review compiles the various modifications to the PEO process that have been used to improve the produced coatings and make them suitable for specific applications, with a focus on examples of aluminum, magnesium, and titanium substrates. An overview of the PEO process is given, highlighting the various process parameters and their effects on the final surface. The challenges with light metals that motivate the use of surface modifications are summarized, along with some of the other modifications that attempt to overcome them. Two broad categories of modifications to the PEO process are presented: in situ modifications, influencing the properties of the coating during its formation, and ex situ modifications, augmenting the properties of an already-formed coating. Finally, specific examples of applications for modified PEO processes are discussed, including battery, biomedical, water treatment, and energy production applications. Full article

(This article belongs to the Collection Feature Paper Collection in Plasma Coatings, Surfaces & Interfaces)

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16 pages, 3780 KiB

Open AccessArticle

The Properties of Self-Compacting Ultra-High Performance Concrete with Different Types of Mineral Admixtures

by Lin Wang, Xiying Tian, Yuefan Pan, Dingyuan Wu, Shengli Xu, Hangyang Wang, Xiaolu Tian, Yubo Xu, Hong Guo and Min Zou

Coatings 2025, 15(5), 591; https://doi.org/10.3390/coatings15050591 - 16 May 2025

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Abstract

This paper investigates the effects of silica fume, cenosphere, fly ash, and ground slag powder on the rheological properties and mechanical strengths of self-compacting ultra-high performance concrete (UHPC). The mass ratio of each mineral admixture varies from 0% to 15%, while the water-binder [...] Read more.

This paper investigates the effects of silica fume, cenosphere, fly ash, and ground slag powder on the rheological properties and mechanical strengths of self-compacting ultra-high performance concrete (UHPC). The mass ratio of each mineral admixture varies from 0% to 15%, while the water-binder ratios are set at 0.18, 0.20, and 0.22. The slump flow and plastic viscosity of fresh UHPC are measured, and the corresponding flexural and compressive strengths of UHPC cured for 3 days and 28 days are determined. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) are employed to elucidate the mechanisms underlying the observed performance changes. The results indicate that the addition of silica fume and mineral powder negatively impacts the fluidity of fresh UHPC but positively affects its plastic viscosity. Conversely, the inclusion of cenosphere and fly ash enhances the fluidity of fresh UHPC while having the opposite effect on its plastic viscosity. Increasing the water-binder ratio improves the fluidity of fresh UHPC but reduces its plastic viscosity. Mechanically, silica fume enhances the strengths of UHPC. In contrast, the cenosphere, fly ash, and mineral powder decrease the strengths of UHPC cured for 3 days but increase those cured for 28 days. UHPC containing silica fume exhibits the most compact hydration products and the lowest content of Ca(OH)₂. Full article

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

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15 pages, 10425 KiB

Open AccessArticle

The Effects of CeO₂ Content on the Microstructure and Property of Duplex Stainless Steel Layer Obtained by Plasma Arc Cladding Technology

by Juan Pu, Di Wu, Xiaohui Shi, Fei Long and Huawei Sun

Coatings 2025, 15(5), 590; https://doi.org/10.3390/coatings15050590 - 16 May 2025

Viewed by 46

Abstract

The mixture powders were designed by adding 0 wt.%~1.0 wt.% CeO₂ into the 2205 duplex stainless steel (DSS) powders. The 2205 DSS cladding layer was prepared on the surface of Q345 steel by plasma arc cladding technology. The effects of different CeO [...] Read more.

The mixture powders were designed by adding 0 wt.%~1.0 wt.% CeO₂ into the 2205 duplex stainless steel (DSS) powders. The 2205 DSS cladding layer was prepared on the surface of Q345 steel by plasma arc cladding technology. The effects of different CeO₂ contents on the macro-morphology, microstructure composition, and corrosion resistance of the cladding layer were studied. The action mechanism of CeO₂ in the cladding layer was also discussed. The results showed that the addition of CeO₂ modified the appearance and decreased the defect of the cladding layer. Also, the austenite grains were refined, and the austenite proportion was increased under the action of CeO₂. When the CeO₂ content was 0.5 wt.%, the appearance of the cladding layer was optimum; the austenite proportion in the upper cladding layer and the lower cladding layer reached up to 52.6% and 55.5%, respectively, and the crystal changed from columnar to equiaxed. CeO₂ decomposes into Ce element and O element under the action of the plasma arc, after which Ce element is easily absorbed at the grain boundary to reduce the surface tension and improve the fluidity of the liquid metal so as to modify the appearance of the cladding layer. Meanwhile, Ce element primarily reacts with O, S, Al, and Si elements to form low-melting-point oxygen sulfides and are then removed, which eliminates the defect of the cladding layer. Moreover, the high melting point of CeO₂ acts as heterogeneous nucleation sites during solidification, thus improving the value of nucleation rate/growth rate of the grain and promoting the transformation from ferrite to austenite. According to the electrochemical corrosion testing result, Ce element inhibited the enrichment of Cr element at grain boundaries and promoted the formation of Cr₂O₃, which improved the corrosion resistance of the 2205 DSS cladding layer. It was optimum with the CeO₂ content of 0.5 wt.%. Full article

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

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16 pages, 18412 KiB

Open AccessArticle

Research on the Influence of Surface Defects Under the Influence of Rail Corrosion on the Fatigue Damage of Wheel Rolling Contact

by Longzhi Zhao, Minghui Mou, Daoyun Chen and Minshi Zhong

Coatings 2025, 15(5), 589; https://doi.org/10.3390/coatings15050589 - 15 May 2025

Viewed by 90

Abstract

Heavy rolling contact fatigue (RCF) may be caused by wheel surface defects under the influence of rail corrosion, which threatens the operational safety of rail vehicles. To investigate the role of surface defects on wheel RCF damage under the influence of rail corrosion, [...] Read more.

Heavy rolling contact fatigue (RCF) may be caused by wheel surface defects under the influence of rail corrosion, which threatens the operational safety of rail vehicles. To investigate the role of surface defects on wheel RCF damage under the influence of rail corrosion, a salt spray tester was used to corrode the rails, an impact testing machine was employed to create surface defects, and RCF tests were completed. The role of surface defects on wheel RCF damage was studied by monitoring the wheel defect surface and cross-section. The results indicate that the tendencies of the RCF crack extension of surface defects of different sizes are similar, and they all extend in a C-shape along the tangential force direction. However, the larger the defect size, the later the crack is initiated. The leading edge material is continuously squeezed into the defect by the tangential force, and a larger plastic deformation layer is formed, which causes the RCF at the leading edge to crack more severely. Meanwhile, under the effect of combined normal force and shear stress, the leading edge crack intersects with the middle edge crack, and the leading edge material is spalled off first. Wheel RCF damage and wear are aggravated by rail corrosion, the longer the corrosion time, the more serious the RCF damage and wear, and the earlier the material spalling time, the lower the fatigue life. Full article

(This article belongs to the Special Issue Advancements in Surface Engineering, Coatings and Tribology)

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14 pages, 5738 KiB

Open AccessArticle

Fluoro-Silicon-Modified Polythiourethane Copolymer for Marine Antifouling Coatings

by Songbo Xie, Xiufen Liao, Yanye Fan, Jiacheng Li, Qiumei Jiang, Yihua Zheng, Zhimin Huang and Shella Li

Coatings 2025, 15(5), 588; https://doi.org/10.3390/coatings15050588 - 15 May 2025

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Abstract

Traditional marine antifouling coatings function through releasing toxic antifouling agents, causing serious harm to marine ecosystems. To address this challenge, an eco-friendly fluoro-silicon-modified polythiourethane (FSi-PTU) coating has been prepared via a polymerization reaction with dihydroxy propyl silicone oil (HO-PDMS-OH), 1H,1H,2H,2H-perfluorohexanol (FTOH), hexamethylene diisocyanate [...] Read more.

Traditional marine antifouling coatings function through releasing toxic antifouling agents, causing serious harm to marine ecosystems. To address this challenge, an eco-friendly fluoro-silicon-modified polythiourethane (FSi-PTU) coating has been prepared via a polymerization reaction with dihydroxy propyl silicone oil (HO-PDMS-OH), 1H,1H,2H,2H-perfluorohexanol (FTOH), hexamethylene diisocyanate (HDI), and pentaerythritol tetrakis (3-mercaptopropionate) (PETMP). The FSi-PTU polymer incorporates siloxane segments and fluorinated side chains, which are inhomogeneously distributed on the coating surface and construct a hydrophobic surface. The FSi-PTU coating exhibits good hydrophobicity, strong adhesion (≥2.14 MPa), and improved mechanical properties. The antifouling properties of the FSi-PTU coating have been researched. The results of laboratory tests demonstrate that the FSi-PTU coating exhibits excellent anti-protein adsorption and anti-algal attachment performance. The FSi-PTU-2 coating shows certain antifouling properties in the actual seawater test for three months. The results provide a certain reference value for developing eco-friendly marine antifouling coatings. Full article

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