Search Results (716)

Yttria-stabilized zirconia (YSZ) thermal barrier coatings suffer from t′ phase destabilization and insufficient thermal insulation above 1200 ℃. In this work, YbO_1.5-stabilized ZrO₂ powders (xYbSZ, x = 4–12 mol% YbO_1.5 on a cation basis, equivalent to 2–6 mol% Yb₂O₃) were synthesized by chemical co-precipitation, consolidated by spark plasma sintering, and evaluated at 1300 ℃ in terms of phase stability, sintering behavior, thermal conductivity, and fracture toughness. A common compositional boundary near 8 mol% YbO_1.5 was identified across all four responses. 8YbSZ retained the metastable t′ phase with a monoclinic content below 10 mol% after 300 h at 1300 ℃, whereas grain coarsening accelerated markedly and the thermal conductivity reduction efficiency per unit doping at 1000 ℃ was approximately halved beyond this composition, with κ decreasing from 2.41 to 1.96 W·m⁻¹·K⁻¹ across the series. The toughness gain produced by thermal treatment fell from 34% (4YbSZ) to about 10% (10–12YbSZ) as the dominant toughening mechanism shifted from transformation and microcrack toughening (4–6 mol%) to ferroelastic domain switching (8 mol%), with both being lost in the compositions in which the cubic phase predominated. These results identify 8 mol% YbO_1.5 as the optimal composition balancing phase stability, sintering resistance, thermal insulation, and mechanical integrity for TBC applications at 1300 ℃. Full article

La₂Si₂O₇ is a candidate environmental barrier coating (EBC) material for silicon carbide ceramic matrix composites in next-generation gas turbine engines, yet its degradation behavior under the simultaneous attack of molten CMAS and water vapor remains insufficiently understood. This study systematically examines atmospheric plasma-sprayed La₂Si₂O₇ coatings exposed to four environments (air, CMAS alone, H₂O/O₂ alone, and combined CMAS + H₂O/O₂) at 1400 °C for 8 h. Under dry air, the coating recrystallizes to La₂Si₂O₇ with negligible corrosion. CMAS attack triggers a dissolution–reprecipitation mechanism forming needle-like CaLa₄(SiO₄)₃O apatite within a denser reaction zone, which partially impedes further infiltration. Water vapor accelerated the growth of the thermally grown oxide at the bond coat interface. The combined CMAS + H₂O/O₂ environment produced a pronounced synergistic acceleration: water vapor reduced CMAS melt viscosity, enabling deeper CMAS penetration, while concurrent silica volatilization disrupted the protective apatite barrier, generating extensive porosity and through-coating cracking. These findings reveal that the inherent CMAS resistance of La₂Si₂O₇ via apatite formation is critically compromised by simultaneous water vapor, highlighting a key challenge for its application in realistic engine environments. Full article

The corrosion-protection performance of zinc oxide-hybrid polymeric coatings is traditionally attributed to the individual contributions of their constituent phases. This study reveals that the calcination temperature of zinc oxide (ZnO) filler is a critical, previously overlooked processing parameter that dictates not only filler crystallinity but also the collective synergistic failure mechanism of the entire coating system. Herein, we demonstrate that incorporating ZnO calcined at 500 °C yields a ternary chitosan–graphene oxide–zinc oxide/epoxy (CS–GO–ZnO/EP) composite coating with a highly compact, dense morphology, minimal internal porosity, and exceptional filler dispersion, as validated by FTIR, XRD, and SEM analyses. The optimized CS–GO–ZnO/EP coating applied to carbon steel exhibits outstanding dry and wet pull-off adhesion strengths, the highest surface hydrophobicity (102.2°), and superior electrochemical barrier protection. Notably, after a 120-h immersion period in an aggressive 3.5 wt.% NaCl electrolyte, the CS–GO–ZnO/EP (500 °C) maintains excellent coating resistance (R_coat = 1.06 × 10⁵ Ω) and a minimized corrosion rate (CR = 0.074 mm/y). This thermal threshold is a key processing window that improves chemical bonding and compatibility between the different parts of the hybrid matrix without causing the severe nanoparticle sintering, phase aggregation, and micro-cracking that happen at 650 °C. This work offers a significant advancement in the design of eco-friendly, high-performance hybrid coatings, demonstrating that precise control of the inorganic phase’s thermal history provides a direct pathway toward superior durability, hydrophobicity, and electrochemical stability for carbon steel protection in aggressive marine environments. Full article

Conventional polydimethylsiloxane (PDMS)-based antifouling coatings, despite their inherent fouling-release capability, exhibit critically insufficient antifouling performance under static seawater conditions. Inspired by the synergistic physical–chemical defense strategy of sessile marine organisms, specifically sea anemones, which combine a physical mucus barrier with antimicrobial peptide secretion, the present work develops a multi-mechanism hybrid coating—designated as sea anemone-inspired fluorosilicone polyurethane—that integrates low-surface-energy physical antifouling and cationic antibacterial chemical antifouling. This coating system is constructed from silicone polyurethane (PDMS-PU), a cationic antibacterial moiety (PDMS-N⁺), and fluorinated functional monomers. Through systematic compositional optimization, an optimal formulation (P-4) is identified, which achieves a fracture elongation of 78.19%, a normal adhesion strength of approximately 2.5 MPa, a water contact angle of 120°, and a surface energy of 12.86 mN/m. Notably, its antibacterial rates against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) exceed 95%. The resultant coating uniquely synergizes low surface energy, potent antibacterial activity, excellent mechanical properties, and thermal stability, thereby enabling long-term and stable antifouling performance in static seawater environments. This work provides a crucial technological foundation for the engineering application and industrialization of green, durable marine antifouling coatings. Full article

Solar-Driven Photothermal Membrane Distillation (SPMD) integrates solar energy using photothermal coatings on the hydrophobic membranes, such as carbon black nanoparticles coated on PVDF membranes, to achieve localized heating at the liquid–vapor interface. This approach enhances energy efficiency by mitigating temperature polarization and reducing thermal energy demands compared to conventional membrane distillation (MD). However, the challenges of fouling and scaling, which can significantly impair membrane performance, continue to be a serious concern, similar to other MD configurations. This comprehensive review establishes a unified framework connecting core transmembrane mass and heat transfer mechanisms with the thermodynamic pathways of surface fouling and scaling. We critically evaluate various strategies for mitigating scaling and fouling, including the development of omniphobic membranes, the introduction of nano/micro bubbles, the addition of anti-scalants and surfactants, and the implementation of chemical and mechanical pretreatments. Subsequently, the impact of photothermal coatings, applied to the feed–membrane interface in SPMD to absorb solar radiation, on scaling and fouling resistance is also discussed. Finally, we provide a comprehensive review of advanced computational paradigms, for both coupled radiative-thermal and dynamic fouling models—contrasting deterministic, physics-based multi-phase Computational Fluid Dynamics (CFD) with empirical Response Surface Methodology (RSM) and predictive Artificial Intelligence (AI) data-driven models. Beyond this survey, we identify and directly address a critical, previously unquantified gap in the field of SPMD: the absence of an explicit thermodynamic link between transmembrane heat/mass transfer and the nucleation and adhesion processes that govern scaling and fouling, and we further highlight the practical barriers—photothermal coating durability, economic feasibility, and technology readiness—that currently separate laboratory-scale SPMD from field deployment. This holistic synthesis charts future engineering strategies for scalable, fouling-resistant, and optimized solar-driven desalination infrastructure. Full article

In this study, 8YSZ thermal barrier coatings (TBCs) were deposited on IC21 single-crystal superalloy substrates. Short-term overheating at 1300 °C was conducted for durations of 1, 5, and 10 min under both uniform temperature and simulated service conditions, followed by thermal cycling and thermal shock tests, respectively, to investigate the short-term overheating behavior of the coatings. The effects of short-term overheating on microstructural evolution and stress evolution under different conditions were analyzed, and the underlying damage mechanisms were determined. The results show that under uniform temperature conditions, short-term overheating drives the continuous growth of the thermally grown oxide (TGO). Coating failure occurs at the specimen edge, dominated by thermal stress concentration induced by geometric edge effects. The stress evolution is relatively mild, and the damage mechanism is primarily long-term interfacial degradation. Under simulated service conditions, short-term overheating induces sintering and cracking in the ceramic top coat. Coating failure occurs at the specimen center, dominated by crack coalescence. Transient temperature gradients generate high non-steady-state thermal stresses. The damage mechanism involves thermomechanical loading accelerating interfacial degradation, with synergistic effects of ceramic layer sintering and TGO destabilization, leading to a significant reduction in coating lifetime. Full article

High-entropy carbide (HEC) coatings have emerged as promising candidates for extreme tribological and high-temperature applications; therefore, the objective of this work is to systematically investigate the correlation between carbon stoichiometry and the microstructural evolution, mechanical response, and thermal stability of (TiAlTaZrNb)Cx high-entropy carbide coatings. Here, HEC coatings were synthesized via reactive unbalanced-field pulsed-bias magnetron sputtering, with methane flow rates precisely tuned to yield carbon concentrations ranging from 24 to 55 at.%. XRD and Raman analyses reveal a transition from a dense, columnar FCC NaCl-type solid solution with a (200) preferential orientation to a (111)-textured matrix containing secondary carbides (TiC, TaC) and sp²-bonded free carbon at elevated carbon levels. Nanohardness and elastic modulus reach an optimal plateau at ~35 at.% C (29 GPa and 350 GPa, respectively), followed by a decline to ~20 GPa and 223 GPa at 55 at.% C due to the percolation of soft carbon-rich phases. Remarkably, increasing carbon content drastically enhances tribological performance: the coefficient of friction decreases from 0.40 to 0.20, and the specific wear rate drops from 35 × 10⁻⁶ to 1.7 × 10⁻⁶ mm³/(N·m), consistent with a solid-lubrication mechanism inferred from as-deposited Raman trends and wear-track compositional analysis, though direct post-wear spectroscopic validation remains a priority for future work. Thermal stability assessments at 600 °C at an intermediate low pressure demonstrate excellent microstructural and mechanical retention for low-to-intermediate carbon compositions, with oxidation confined to a ~200 nm surface layer attributed to the formation of stable titanium and tantalum oxides and oxycarbides, which possibly forms an oxygen diffusion barrier at that temperature. An optimal carbon content of ~35 at.% C delivers a superior synergy of high hardness, exceptional wear resistance, and robust thermal stability, establishing (TiAlTaZrNb)Cx as a highly tunable coating system for next-generation protective applications. This work provides the first systematic composition–performance map for this quinary HEC system across a broad stoichiometric range, demonstrating that carbon stoichiometry serves as a master variable to tailor the balance between mechanical integrity and tribological functionality. Full article

The scientific literature on plasma methods for modifying the surface properties of non-woven polypropylene (NWPP) fabrics is reviewed. The scientific background of the observations reported by different teams is explained, and the technological limits are highlighted. Plasma treatment usually modifies the surface layer, which is beneficial for some applications, such as grafting functional coatings onto the fibers in the surface film of NWPP fabrics. The water contact angle of NWPP fabrics treated by plasmas sustained by the classical dielectric barrier discharges at atmospheric pressure and low-pressure discharges in the range of about 10 to a few 100 Pa rarely drops below 90°, which is explained by the inability to modify fibers deep in the fabrics due to the limited penetration depth of such plasmas. The super-hydrophilic finish can be achieved either by using nanosecond-pulsed atmospheric-pressure discharges or by weakly ionized plasma with a relatively high electron temperature, sustained at a pressure of a few Pa or below. Such plasmas modify the fibers deep in the fabric, which is particularly useful for applications in respiratory masks where the fibers should be coated with ultra-thin films of virucidal substance. The energy efficiency of the latter plasmas is better because practically no gas-phase loss of reactive species occurs, and so is their scalability, making them the most suitable for modifying NWPP fabrics at an industrial scale. While most authors reported only increased wettability with increasing treatment intensity, over-treatment has been reported and is attributed to thermal effects. The range of optimal intensity has yet to be systematically quantified. Full article

Polybenzoxazines (PBz) represent a versatile class of high-performance thermosetting polymers that have attracted significant attention for advanced composite applications due to their unique combination of properties including high glass transition temperatures, low polymerization shrinkage, excellent thermal stability, and molecular design flexibility. This comprehensive review examines the structure–property relationships governing PBz composite performance, from molecular design principles through network formation, composite reinforcement strategies, and ultimate application performance. The review systematically addresses benzoxazine monomer structure and its influence on polymer network architecture, explores the polymerization mechanism, and critically evaluates composite design strategies incorporating carbon-based nanofillers, fiber reinforcements, and hybrid filler systems. Detailed analysis of structure–property relationships reveals how molecular and composite architecture control thermal stability (glass transition temperatures exceeding 350 °C and char yields up to 92%), mechanical performance, electrical properties (dielectric constants as low as 2.67), and chemical durability. Processing techniques ranging from conventional compression molding to emerging additive manufacturing approaches are discussed in the context of morphological control and property optimization. Applications spanning aerospace structures, high-frequency electronics and protective coatings demonstrate the technological relevance of PBz composites. Critical challenges including network brittleness, high cure temperatures, and recyclability limitations are addressed alongside recent advances in dynamic covalent networks, vitrimer chemistry, and self-healing systems that promise to overcome these barriers. This review provides a comprehensive framework for understanding and engineering polybenzoxazine composites for next-generation advanced applications. Full article

In this study, warm shot peening was applied to Ti-Al coatings to investigate its effect on high-temperature oxidation behavior at 800–1000 °C. WSP induced severe plastic deformation and thermal effects, resulting in grain refinement, increased lattice distortion, and TiAl-to-Ti₃Al phase transformation, thereby enhancing the structural stability of the coating matrix. Cyclic oxidation kinetics revealed a two-stage process transitioning from reaction-controlled to diffusion-controlled behavior. WSP delivered prominent protective effects at intermediate temperatures, substantially reducing oxidation weight gain and rate constants by promoting the formation of dense, stable Ti₂O₃ and Al₂O₃ protective layers with finer, more uniform oxide-scale morphology. However, this beneficial effect progressively weakened with increasing temperature and sharply diminished at 1000 °C, where massive generation of porous, thermally unstable TiO₂ dominated the oxidation process. The loose TiO₂ structure provided channels for inward oxygen diffusion, offsetting the microstructural optimization advantages of WSP and compromising oxide-scale barrier effectiveness. These findings establish a clear structure–performance correlation for WSP-modified Ti-Al coatings and elucidate the temperature-dependent failure mechanism of surface modification under ultra-high-temperature oxidation conditions. Full article

Thermally sprayed metallic coatings on carbon fiber-reinforced polymer (CFRP) substrates often contain pores and microstructural defects that can reduce adhesion, durability, and protective performance. In this study, a hybrid graphene nanoplatelet (GNP)-fullerene C60 reinforced epoxy coating was applied to HVOF-metallized CFRP, while a carbon nanotube (CNT)-based surface treatment was used to modify surface wettability. Micro-CT and SEM analyses indicated morphological changes consistent with partial coverage of accessible surface-connected defects and modification of the metallized layer surface. Pull-off adhesion strength increased from 320 psi to 650 psi, accompanied by a shift from adhesive to cohesive failure. The optimal nanofiller formulation improved tensile strength from approximately 25 MPa to 56 MPa (124%) and Young’s modulus by approximately 47% compared with neat epoxy. Abrasion testing showed more than 50% reduction in mass loss, and electrochemical impedance spectroscopy indicated improved barrier performance after 200 h of salt spray exposure. CNT surface modification transformed the coating from hydrophilic to superhydrophobic behavior, achieving water contact angles above 155°, delaying ice formation, and reducing ice accumulation. These results indicate that combining hybrid nanocomposite coatings with CNT functionalization can improve mechanical, protective, and surface-functional performance of HVOF-metallized CFRP systems under the laboratory conditions investigated. Full article

Rosin- and castor-oil-derived resins provide a renewable platform for rapidly curable protective coatings, but the effects of formulation and curing route remain insufficiently resolved. Four composite formulations containing modified rosin glycerol ester (MRGE) and modified castor oil anhydride (MCOA) were cured thermally using ultraviolet irradiation or electron beam (EB) irradiation. Surface C=C conversion, thermal behavior, morphology, mechanical properties, neutral salt spray resistance, electrochemical barrier performance, and AC dielectric breakdown strength were evaluated. Among the formulations tested, F2 (MRGE/MCOA = 3:1) showed the best overall property balance under each curing route. For F2, EB curing produced a surface C=C conversion of 92 ± 2%, a glass transition temperature of 88 ± 1 °C, an 800 °C residue of 12.5 ± 0.3%, and an atomic force microscope (AFM) roughness Ra of 5.8 ± 0.5 nm. F2-EB exhibited 9H pencil hardness, 5B adhesion, an impact resistance of 55 ± 2 cm·kg, and a flexibility value of 1.0 ± 0.1 mm. After 500 h of neutral salt spray, both F2-EB and F2-UV achieved a protection rating of 10 with no measurable corrosion creep at the scribe; time-resolved photographs at 100, 300, and 500 h confirmed that F2-EB showed the least visible damage evolution among the three curing routes. After 1 day of immersion in 3.5 wt% NaCl, F2-EB exhibited the largest low-frequency impedance and the lowest fitted corrosion current density among the EB-cured formulations, indicating the strongest short-term electrolyte barrier behavior. The AC dielectric breakdown strength of F2-EB reached 21.5 ± 0.3 kV mm⁻¹. The combined results are consistent with more extensive EB-induced network formation, although direct measurements of through-thickness conversion and crosslink density are still required. These findings demonstrate the potential of EB curing for rapidly preparing rosin/castor-oil-derived protective coatings for electrical insulation applications. Full article

The growing demand for environmentally sustainable materials has accelerated the development of bio-based coatings as alternatives to conventional petroleum-derived surface treatments. Among renewable biopolymers, lignin has emerged as a particularly attractive candidate owing to its abundance, renewable origin, aromatic structure, antioxidant activity, ultraviolet shielding capability, and diverse functional groups suitable for chemical modification. As a major by-product of the pulp, paper, and biorefinery industries, lignin represents an underutilized renewable resource with significant potential for value-added coating applications. This review provides an overview of recent advances in lignin-based coatings for sustainable and biodegradable materials. The chemical structure, physicochemical properties, industrial sources, extraction technologies, purification methods, and functionalization strategies of lignin are discussed. Particular attention is given to nanostructured lignin systems, including lignin nanoparticles (LNPs) and chemically modified derivatives, which have demonstrated improved compatibility and performance in coating formulations. Fabrication technologies such as solution casting, dip coating, spray coating, layer-by-layer (LbL) assembly, extrusion processing, and nanocomposite approaches are examined. Mechanical, barrier, thermal, UV-shielding, antioxidant, antimicrobial, hydrophobic, and environmental performance are comparatively assessed. Lignin nanoparticles and chemically modified lignins generally show improved functionality, while waterborne coatings for paper and fiber-based packaging appear closest to practical application. However, lignin heterogeneity, durability, scalability, and limited regulatory evaluation and end-of-life assessment remain major barriers to commercialization. Full article

The issue of thermal runaway in power batteries of new-energy vehicles occurs frequently, posing a serious threat to life and property safety. This study aims to develop a high-performance fire-proof coating to address this problem. Specifically, the research focused on constructing an organic-inorganic composite intumescent fire-resistant coating, with modified halloysites (Ti-HNTs) serving as the key component. In this coating system, the intumescent flame-retardant (IFR) system and Ti-HNTs were employed as the organic and inorganic components, respectively, while water-based epoxy resin emulsion was selected as the matrix material. Through the utilization of XPS, FTIR, and SEM techniques, it was verified that the Ti-HNTs were successfully modified and integrated well with the coating matrix. Following further optimization of the Ti-HNTs proportion and coating thickness, it was determined that the coating containing 4% Ti-HNTs with a designed thickness of 1.5 mm exhibited the optimal fire-proofing performance. In the fire-resistance experiment, after 10 min of testing, the temperature of this coating could reach a minimum of 215.9 °C. Compared to the control group, its heat-insulation effect was enhanced by 49.4%, with an expansion multiplier of 37.7 and a maximum smoke density of 22.55. These results were significantly superior to those of the control group without the addition of Ti-HNTs. SEM analysis indicated that the coating could form a uniform and dense carbon layer, with an inner surface featuring a honeycomb-bubble structure. This SEM-analyzed Ti-HNTs-modified fire-proof coating demonstrated excellent fire resistance and thermal-isolation effects in new-energy vehicle batteries, thus providing reliable fire protection for the batteries. Additionally, impact-resistance tests revealed that the coating could withstand a simulated battery pressure-relief impact without penetration, maintaining its structural integrity and thermal-barrier function. This further validated its reliability for battery fire protection. Full article

To investigate the influence of particle size on the erosion damage behavior and failure mechanisms of thermal barrier coatings (TBCs) in a simulated aero-engine erosion environment, erosion tests were conducted using Al₂O₃ particles of different sizes (65 μm, 120 μm, and 175 μm) under a nominal gas-flow condition of Mach 0.4 at 1150 °C with custom-built multi-factor coupled erosion test equipment. TBCs were prepared using electron beam physical vapor deposition (EB-PVD). By combining macroscopic/microscopic morphology, composition, white-light interferometry, and Raman residual stress testing, the damage evolution and failure behavior of TBCs under different particle size conditions were analyzed. The results indicate that particle size has a significant effect on the erosion behavior of thermal barrier coatings. Under erosion conditions involving 65, 120, and 175 μm particles, the erosion rates were 10.83, 4.19, and 2.05 g/kg, with corresponding coating lifetimes of approximately 3, 12, and 22 h. As particle size increases, the erosion rate decreases and the coating lifetime increases. Under small 65 μm particles, the coating exhibits high-frequency continuous micro-cutting. The ceramic layer rapidly thins, leading to localized penetration. Under erosion by 120 μm particles, the coating exhibits a composite damage mechanism involving cutting, compaction, and brittle fracture. Under large-particle impacts of 175 μm, the damage mechanism is dominated by localized brittle fracture and spalling induced by high-energy impacts. Although the single-impact energy of large-particle impacts is higher, the lower particle number density results in a discrete distribution of damage zones, leading to a lower material removal rate. The Raman test results further indicate that, after 2 h of erosion, the differences in residual stress in the TGO layer were relatively small across different particle size conditions, suggesting that the early degradation process of the coating is primarily controlled by the mechanical removal of the ceramic surface layer rather than by the evolution of TGO stress. No statistically significant difference in TGO residual stress was observed among different particle sizes after 2 h of erosion (p > 0.05). Not only is the erosion life of EB-PVD YSZ TBCs is influenced by the impact energy of individual particles, but more importantly, it is also closely related to particle number density, impact frequency, and the spatial distribution of damage. Full article