Chemistry and Materials Science

Abstract: Cysteine-stabilised silver nanoparticles (cys-AgNPs) were prepared in a one-pot aqueous synthesis in which AgNO₃ was reduced with NaBH₄ and the particles were capped with cysteine at room temperature. Formation of the particles was indicated by a colour change from colourless to yellow and then reddish-brown, with a localised surface plasmon resonance (LSPR) band at 401 nm that changed little over 100 min. UV-vis, FTIR, TGA, CHNS microanalysis, powder XRD, SEM and TEM were used for characterisation. These techniques indicated crystalline face-centred cubic silver of about 5–48 nm with a bimodal size distribution. They also showed a substantial organic fraction (about 40–53 wt%), with cysteine probably bound to the silver surface through the thiol group. Addition of Cu(II), Ni(II) and Au(III) (2–20 ppm) caused a rapid colour change and a marked decrease and shift of the LSPR band within 5 min. Batch experiments with Cu(II) and Ni(II) examined the effects of initial concentration, contact time, adsorbent dose, pH and temperature. Uptake reached about 10 mg g⁻¹ at 20 ppm, was fast (Cu(II) near-complete within 5 min), followed pseudo-second-order kinetics and was best described by the Henry isotherm. Ni(II) uptake increased with temperature and with pH. These results show that cys-AgNPs can bind Cu(II) and Ni(II) rapidly from dilute solution and are a candidate material for combined colorimetric sensing and removal of heavy metals. Selectivity, working capacity and performance in real wastewater still need to be established.

Abstract: The development of efficient visible-light-responsive photocatalysts is essential for the sustainable remediation of water contaminated with persistent organic pollutants. In this work, BiAlO₃ perovskite was investigated as a pristine photocatalyst for the first time for the visible-light-driven degradation of Rhodamine B (RhB). The synthesized material exhibited a well-crystallized rhombohedral perovskite structure, while electron microscopy revealed irregularly aggregated particles composed of nanoscale structural features. Surface chemical analysis confirmed the presence of Bi³⁺, Al³⁺, and oxygen species. Optical characterization revealed an optical band gap of approximately 2.7 eV, together with pronounced energy-dependent dielectric, conductivity, and charge-relaxation responses, indicating favorable light–matter and charge-dynamic characteristics. Under visible-light irradiation, BiAlO₃ achieved 87.54% RhB degradation within 90 min, compared with only 9.63% removal by direct photolysis, demonstrating its intrinsic photocatalytic activity. Scavenger experiments revealed that photogenerated holes and hydroxyl radicals make the dominant contributions to RhB degradation, followed by photogenerated electrons and superoxide radicals, with an approximate contribution order of h⁺ > •OH > e⁻ > •O₂⁻. The photocatalyst also retained approximately 75% degradation efficiency after six consecutive cycles, demonstrating good operational stability and reusability. The combination of a relatively narrow band gap, favorable optical and charge-dynamic characteristics, efficient visible-light photocatalytic activity, and satisfactory cycling stability highlights BiAlO₃ as a promising lead-free perovskite photocatalyst for organic pollutant remediation. More broadly, this work establishes the previously unexplored BiAlO₃/RhB photocatalytic system and provides new insight into the relationship between the intrinsic optical and charge-dynamic properties of BiAlO₃ and its photocatalytic performance.

Abstract: Although additive manufacturing enables the production of metallic components with complex geometries, accurately characterizing their surfaces remains challenging, especially in regions beyond the reach of conventional techniques. To address this challenge, this study investigates scanning acoustic microscopy (SAM) as an automated, non-destructive method for measuring the surface roughness of stainless steel 316L cubes fabricated by selective laser melting. A dedicated image-processing pipeline was developed to detect the water–specimen interface in SAM B-scan images and convert it into a calibrated surface profile. ISO-based spatial filtering was then applied to separate roughness from measurement noise, waviness, and surface form. The resulting profiles were used to calculate R_a, R_q, R_p, R_v, and R_t. R_a was used as the common parameter for quantitative validation of SAM against reference standards. For nominal values of 12.5, 25, and 50 μm, SAM measured 12.92, 28.53, and 51.60 μm, corresponding to absolute deviations of 0.42, 3.53, and 1.60 μm, respectively. The repeatability assessment showed coefficients of variation below 1%, indicating precise measurements. Following this assessment, the proposed pipeline was applied to the fabricated cubes and compared with digital light and laser confocal microscopes. Overall, the findings show that SAM can distinguish different roughness levels and provide reliable quantitative measurements.

Abstract: Corrosion remains a major industrial challenge, compromising material durability and generating substantial economic costs. Conventional hexavalent chromium (Cr(VI)) compounds provide active protection but face restrictions due to toxicity. Hybrid organic–inorganic sol-gel coatings offer a versatile platform for chromate-free corrosion protection. This work investigates the physicochemical characteristics and corrosion performance of a cerium-containing hybrid organic–inorganic sol-gel coating based on 3-mercaptopropyltrimethoxysilane (MPTS). To enhance environmental sustainability, the coating was formulated with 60 vol.% alcohol, compared with ≈95 vol.% in literature benchmarks, and incorporated 5 wt.% cerium, reducing volatile organic compound use while eliminating Cr(VI). Chemical structure, morphology, elemental distribution, adhesion, cerium release, and electrochemical performance were evaluated by ATR-FTIR, SEM- EDS, an ASTM D3359- adapted cross-hatch test, ICP-MS, and EIS. ATR-FTIR confirmed polysiloxane network formation, while SEM-EDS revealed a homogeneous surface distribution of cerium-containing nodules. The coating achieved a 4B adhesion rating and sustained cerium release of 21.2 µg after 1 week in 3.5 wt.% NaCl. EIS demonstrated a low-frequency impedance modulus of 9.03×10⁵ Ω⋅cm² after 1 week and improved electrochemical response in artificially damaged coatings versus Ce-free control. Combined adhesion, sustained cerium release, and electrochemical protection highlight this sustainable hybrid sol-gel formulation for high-performance chromate-free corrosion protection.

Abstract: Metal-halide perovskite solar cells combine high photovoltaic efficiency with low-temperature solution processing, but their performance and durability remain sensitive to precursor coordination, nucleation, drying, grain-boundary formation, and interfacial degradation. This critical narrative review evaluates plant-derived secondary metabolites as process-active additives rather than assuming that biological origin alone confers sustainability or passivation. Evidence is organized for alkaloids and xanthines, polyphenols and phenolic acids, and terpenoids and carotenoids, with explicit separation of experimentally demonstrated mechanisms, computational support, molecular analogy, and design hypotheses. Carbonyl-mediated coordination provides the clearest mechanistic basis for caffeine and related xanthines, whereas selected phenolic compounds have been associated, in separate studies, with coordination, crystallization control, and suppression of Sn²⁺ oxidation. Direct photovoltaic evidence now includes selected monoterpenoids, the sesquiterpene lactone artemisinin, and carotenoids, although the results remain molecule- and process-specific and do not justify class-wide generalization. The review maps molecular descriptors onto precursor chemistry, coating and crystallization variables, film structure, recombination, ion migration, device performance, and stability. Translation beyond laboratory spin coating will require specification-controlled additives, standardized stability protocols, process-compatible formulations, and iterative computational–experimental screening. This evidence-based framework identifies secondary-metabolite scaffolds as a promising but molecule-specific platform for perovskite process engineering, whose sustainability benefit remains to be established through life-cycle assessment.

Abstract: Ecological driven sustainability of plastic materials encounters a major challenge in eco-efficient mechanical recycling falling short of meeting the required quality and quantities of post-consumer-recyclates (PCR) in sensitive applications areas demanded by regulatory authorities. Remaining toxicological concerning residues of contaminants after mechanical recycling restrict the use in sensitive application areas. Addressing the integration of PCR into high demanding applications, such as food contact materials, this work investigates a novel technology for PCR product use by an innovative migration barrier development pathway of Si-based plasma enhanced chemical vapour deposition (PECVD) coatings on pre-contaminated polypropylene (PP) model PCR cups compliant with applicable regulatory frameworks including European Food Safety Authority (EFSA) authorization requirements. As a starting point for migration barrier development optimized oxygen transmission rate (OTR) barrier coatings for PCR cups were reproduced and transferred on virgin and model PCR PP-cups. The coating procedure consisted out of a pretreatment, applied organic adhesion interlayer SiOCH and inorganic functional barrier layer SiOx, where the functionality was related to the applied SiOx layer based on the barrier efficiency. Therefore, SiOx was varied in the migration barrier development to find a suitable process window and efficiently correlate the effects of process parameters on OTR before and after migration testing, mass loss of simulant and the reduction of migration of eight introduced contaminants in the model PCR cup using GC/MS. This work advanced the understanding of PECVD as migrations barriers under regulatory frameworks and reduced PCR matrix complexity in the analysis during development using model PCR cups.

Abstract:

On 304 stainless steel substrates, two combined systems based on silver particle semiconductors, Ag/TiO₂ and Ag/SiO₂, were formed. Such systems were applied in the photocatalytic degradation, profiting from sunlight, of nitrosamines, which are highly toxic substances, specifically N-Nitrosodiethanolamine. The synthesis of TiO₂ and SiO₂ was carried out by the sol-gel method with co-precipitation of Ag metallic particles, adding a quaternary-ammonium-based ionic liquid as reducing agent. The photocatalysts were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and x-ray diffraction (XRD), confirming the integration of anatase-phase TiO₂ and amorphous-phase SiO2 and the Ag cubic structure. The band gap width was determined by means of the Tauc graphical method, finding 1.7 eV and 1.8 eV for SiO₂ and TiO₂, severally. The photocatalytic evaluation occurred under direct sunlight irradiation, achieving degradation efficiencies above 98 % during the first 30 min; in addition, organic matter was quantified through the chemical oxygen demand (COD) technique.

Abstract: Glaucoma drainage device (GDD) surgery is frequently limited by postoperative fibro-blast proliferation, leading to device failure and the need for revision procedures. In this work, we developed a spray-assisted layer-by-layer (LbL) drug delivery system for GDD surfaces that enables localized release of antiproliferative agents, aiming to standardize patient care. Multilayer thin films composed of poly(β-amino ester) (PBAE) and a 5-fluorouracil (5-FU) and β-cyclodextrin (β-CD) complex (5-FU:β-CD) were fabricated, without (type A films) and with (type B films) graphene oxide (GO) barrier layers. Film growth was monitored by ultraviolet–visible spectroscopy (UV-Vis) and vacuum ultraviolet spectroscopy (VUV), confirming consistent, sequential deposition; type A films exhibited greater reproducibility than GO-containing type B films. Drug release studies revealed a rapid burst release within the first 5 min, fol-lowed by a plateau, regardless of GO incorporation. Cell cycle analysis confirmed that β-CD complexation preserved the biological activity of 5-FU, which induced an S-phase arrest in a dose-dependent manner. Although further optimization of film archi-tecture and composition is required to achieve sustained release, this study demon-strates the feasibility of spray-assisted LbL coatings as a localized drug delivery strate-gy for GDD surfaces. Overall, these findings establish a promising platform for the fu-ture development of more effective and standardized coatings for glaucoma surgical devices.

Abstract: The focus of this study is aimed at generating hollow cathode discharge (HCD) plasma inside three types of polymer tubes, resulting in the activation of tube's inner surfaces. To achieve this goal, both theoretical calculation and experiments were carried out to prove the adopted methodology was feasible. By applying optical emission spectroscopy, with line ratio and modified Boltzmann's plot methods, the plasma sheath could be estimated and applied to the prediction of HCD generation. To verify whether HCD prevails in the tube, the various power input (70 ~ 260 W), tube diameter (3 ~ 7 mm), and working pressure (0.1 and 0.4 torr) were selected. Accordingly, it was confirmed that the tube diameter must be greater than twice the plasma sheath, in order to form HCD, which would then activate the surface. Ar gas was used with a capacitive-coupled RF plasma system. PET, PU, and PTFE tubes were used in this study. The tubes’ inner surfaces were characterized with XPS, and water-contact-angle (WCA) analysis. The results also show that once HCD is generated inside the tubes, these tubes’ inner surface could become hydrophilic, and the values of WCA might decrease by 40°, 45° and 70° respectively for PET, PU, and PTFE, due to the combine effects of the enhanced ion bombardment and radical oxidation. XPS studies show that, for PET and PU, C-O and, particularly, C=O bonds increase significantly. For PTFE, the C-F bonds decrease, while carbonoxygen bonds increase. Overall, the surface activation is thought to be enhanced by ion bombardment attributable eventually to hollow cathode effect (HCE).

Abstract: Nano-size-induced shifts in alloy phase-separation critical temperatures (T_C^nano) are explored by introducing an atomistic concept concerning site-specific contributions to the shift (SSCS) associated with several types of coordination in cuboctahedral and truncated-octahedral nanoparticles (NPs). T_C^nano computed before by the Free-energy Concentration Expansion Method (FCEM) for the transformation of three small quasi-Janus Pd-Ir NPs to mixed nanophases is expanded to a much wider range of 22 sizes (147-49,049 atoms), forming a database for the modeling. The main goal of the study is to unravel the deviations of the critical temperature shifts in small NPs from the finite-size-scaling (FSS) inverse-size power law (n^-1), previously proposed in thermodynamic non-atomistic modeling. In the framework of the present SSCS approach, this is done in terms of face, edge, and vertex contributions, which are proportional to the relative fraction of each type of these surface sites and are also approximated by n^-1, n^-2, and n^-3, respectively. The introduced SSCS can be applied also to other transitions in nanoparticles with diverse shapes and sizes.

Abstract: Ag-Ti₃SiC₂ composites are promising electrical contact materials, yet the atomic-scale interfacial behavior between Ti₃SiC₂ and Ag remains poorly understood. Here, first-principles calculations were performed to investigate the interfacial stability, electronic structure, and alloying effects at the Ti₃SiC₂(0001)/Ag(111) interface. Surface-energy calculations for six terminations of Ti₃SiC₂(0001) show that the TiC(TiC) termination is preferred at low carbon chemical potential, whereas the TiC(TiSi) termination becomes the most stable once ΔμC exceeds -1.50 eV. Eighteen interface models combining the six terminations with three stacking sequences (OT, MT, and HCP) were constructed, and their work of adhesion (W_ad) and equilibrium spacing (d₀) were determined by the Universal Binding Energy Relation and full structural relaxation. The HCP stacking is preferred for all terminations, and the C(TiC)-terminated HCP interface is the most stable, with W_ad = 9.25 J/m² at d₀ = 1.2 Å; relaxation enhances W_ad by 10-75%. Charge density, charge density difference, and partial density of states analyses reveal that the interfacial bonding is dominated by C 2p-Ag 4d hybridization accompanied by electron transfer from Ag and Ti atoms to the interfacial C atoms, which accounts for the adhesion hierarchy. Substitutional alloying with Cu, Ni, Zn, and Cr is energetically most favorable within the interfacial Ag layer, and W_ad increases in the order Cu < Zn < Ni < Cr, reaching 11.0 J/m² for interfacial Cr, an enhancement of 19% over the pristine interface. The strengthening correlates directly with the filling of the dopant 3d band. These results provide theoretical guidance for the interfacial design of high-performance Ag-Ti₃SiC₂ electrical contact composites.

Abstract: In recent years, carbon nano-onions (CNOs), together with their functionalized derivatives, nanocomposites, and nanohybrids, have attracted increasing attention as sensing materials for monitoring relative humidity (RH), gases, and temperature. Their concentric graphitic structure provides good electrical conductivity, chemical and thermal stability, accessible surface sites, tunable surface chemistry, and compatibility with polymer matrices and flexible substrates. This review highlights recent advances in the synthesis and functionalization of CNOs and examines their integration into chemiresistive, surface acoustic wave, flexible, and printed sensing platforms. Particular attention is devoted to pristine and oxidized CNOs, heteroatom-doped materials, and composites incorporating hydrophilic or conducting polymers, metal oxides, and other functional fillers. CNOs-based sensing layers demonstrate room-temperature (RT) detection of RH, hydrogen, ammonia, acetone, ethanol, isopropanol, carbon dioxide, hydrogen sulfide, and other volatile organic compounds. In addition, CNOs and CNOs–polymer films exhibit significant temperature-dependent variations in resistance, supporting their potential use in flexible and wearable temperature sensors. Although several CNOs-based devices show superior performance in sensitivity, response, recovery characteristics, mechanical flexibility, and low-power operation, the studies on CNOs available in the literature remain limited compared with those on carbon nanotubes, graphene derivatives, and other carbonaceous materials. Further progress on CNOs-based structures requires reproducible, large-scale synthesis; improved film uniformity and selectivity; standardized testing; compensation for temperature–humidity cross-sensitivity; and long-term stability studies. This review concludes by highlighting research directions to bridge the gap between laboratory prototypes and commercially viable CNOs-based sensing devices.

Abstract: 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 (xYbSZ, x = 4–12 mol%) powders were synthesized by chemical co-precipitation, consolidated by spark plasma sintering, and systematically 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 the 4–6 mol% compositions destabilized rapidly and the 10–12 mol% compositions progressively developed the cubic phase. Grain coarsening accelerated markedly above 8 mol%, and the thermal-conductivity reduction efficiency per unit doping at 1000 ℃ was approximately halved beyond this composi-tion, with κ decreasing from 2.41 to 1.96 W·m^-1·K^-1 across the series, consistent with the saturation of point-defect phonon scattering. In the as-prepared state the fracture toughness decreased monotonically with doping, and 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%), both being lost in the cubic-dominated compositions. 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 ℃.

Abstract: AlSb film has attracted the attention for its excellent properties, and many preparation methods have been explored. Herein, AlSb thin films were prepared by DC magnetron co-sputtering method and the interfacial behavior between the films and air molecules were investigated by X-ray diffraction（XRD）, Auger electron spectroscopy (AES) testing and density functional theory (DFT) calculations to elucidated the deliquescence process of AlSb thin films and its underlying mechanism. The results revealed that AlSb thin film exhibited Sb₂O₄ and Sb₂O₅ phases while the thin films doped Cu no longer showed any Sb oxide phases after the film exposed to air for one day. The chemical state of aluminum in the film remained stable along the depth direction, whereas antimony exhibited a pronounced gradient in chemical state from the surface to the interior. The oxidation state of Sb ions varied from -3 in the interior to +5 at the surface. The interaction between the (111) crystal plane of the AlSb film and air molecules is an exothermic process, with water molecules exhibiting the highest adsorption energy on the film surface, followed by oxygen molecules. The adsorption energies for nitrogen and carbon dioxide molecules were the lowest. Consequently, AlSb molecules readily combine with H₂O molecules. Furthermore, doping the AlSb film with copper or zinc atoms effectively reduced the adsorption energy for water and oxygen molecules, offering a new approach to suppress the deliquescence and oxidation of AlSb thin films. This study provides an important theoretical foundation for subsequent research on this material system.

Abstract: Silica aerogel films are highly promising matrices for advanced optical applications, yet balancing ultra-high transmittance with structural stability during functionalization remains a critical challenge. Directly incorporating organic dyes often leads to aggregation and severe photodegradation, necessitating a robust host-guest encapsulation strategy. Herein, we report the fabrication of ultra-transparent, fluorescent silica aerogel films via precisely tailored acid/base two-step sol-gel kinetics and dip-coating. The optimized pure silica matrix achieves a peak visible transmittance of 97.4% and sub-nanometer surface smoothness (RMS = 276.7 pm). By utilizing this pristine network, Rhodamine 6G (Rh6G) and Rhodamine B (RhB) dyes were effectively confined within the amorphous mesoporous pores. Notably, RhB exhibited superior matrix integration, indicated by an H4 hysteresis loop transition and a significantly reduced pore volume (0.019 cm³/g). This mesoporous confinement successfully suppressed dye quenching, prolonging the fluorescence lifetimes to 5.22 ns and 5.36 ns for Rh6G and RhB, respectively. Crucially, we elucidate that the electrostatic and hydrogen-bonding interactions between the silica pore walls and the dye's xanthene rings elevate the excited-state energy, inducing a distinct matrix-driven emission blue shift. This work provides a scalable pathway for high-performance optical coatings and offers deep insights into host-guest interfacial coupling in gel networks.

Abstract: Coating technologies are essential for improving material surface properties while preserving bulk performance. They are widely used to enhance wear resistance, corrosion protection, thermal stability, biocompatibility, and functional behavior in aerospace, automotive, biomedical, electronics, and energy applications. Together with conventional electrochemical methods, the field has advanced to sophisticated techniques such as physical vapour deposition (PVD), laser cladding, chemical vapour deposition (CVD), atomic layer deposition (ALD), and other precision surface modification processes, enabling greater control over coating composition, thickness, microstructure, and adhesion. Recent progress in materials science, nanotechnology, and process engineering has led to multifunctional coatings with enhanced mechanical, thermal, chemical, and biological properties. At the same time, growing sustainability demands have encouraged the development of coating systems with improved durability, reduced environmental impact, and greater process efficiency. This review summarizes recent advances in coating technologies, focusing on major deposition methods (such as PVD, CVD, laser cladding and electrodeposition), coating materials, and applications for high-performance and sustainable material systems.

Abstract: Corrosion of carbon steel in chloride-rich environments remains a critical challenge for marine and industrial applications, necessitating the development of durable protective coating systems. This study evaluates the corrosion resistance of an intelligent coating in comparison with the commercial coating Intertherm 228 HS under accelerated salt spray exposure following ASTM B117. Coated carbon steel specimens were subjected to 1 and 5 wt.% NaCl solutions at pH 4 and 7, temperatures of 35 and 50°C, and exposure durations of 24, 96, and 168 h. Corrosion behavior and coating degradation were characterized using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The results demonstrate that corrosion severity increases with chloride concentration, acidic conditions, elevated temperature, and prolonged exposure. SEM analysis revealed the progressive formation of pits, perforations, and corrosion products, while EDS showed increasing oxygen and chlorine contents accompanied by a decline in iron content, indicating accelerated coating deterioration and substrate corrosion. Compared with the commercial coating, the intelligent coating exhibited superior resistance to chloride-induced degradation, maintaining greater surface integrity and delaying corrosion propagation under all exposure conditions. These findings highlight the strong influence of environmental parameters on coating performance and demonstrate the potential of intelligent coatings to provide enhanced long-term corrosion protection for carbon steel structures operating in aggressive chloride-containing environments.

Abstract: Silver (Ag)-based conductive coatings are widely used in electrical contacts due to their excellent electrical conductivity, low contact resistance, good thermal stability and oxidation resistance, although their susceptibility to sulfidation and environmental corrosion is a concern under certain service conditions. In recent years, significant progress has been achieved in both the manufacture and performance optimization of Ag-based coatings to satisfy the demanding requirements of modern electrical and electronic systems. This review summarizes recent advances in fabrication techniques and processing parameters for Ag-based coatings, including electroplating, electroless deposition, magnetron sputtering, electrospark deposition, thermal spraying, and electrical explosion spraying on metallic substrates, particularly on copper and steel substrates. More attention is given to microstructural design strategies, such as the incorporation and homogeneous dispersion of reinforcement or solid lubricant phases within the Ag matrix, to enhance contact reliability and operational endurance. The performance of Ag-based coatings is analyzed in terms of their physical, chemical and mechanical properties, electrical contact resistance, friction and wear behavior, arc erosion resistance, and environmental durability under different service conditions. Key challenges, including coating degradation under high electrical loads, mechanical wear, and corrosive environments, are highlighted. Future research directions are outlined, focusing on multifunctional coating structures that enhance surface performance and ensure the long-term durability of electrical contacts.

Abstract: To solve the drawbacks of conventional long-cycle wear tests for miniature standing- wave linear ultrasonic motors, an accelerated equivalent wear model and test system were proposed in this work. After primary screening of multiple friction pair materials, graphite and Al2O3 were adopted to modify epoxy films. The optimal friction pair is composed of 6061 hard anodic oxidation film and ECA105 composite film. The matched pair exhibits excellent driving stability and low wear loss, with fatigue wear as the main wear form. Graphite and Al₂O₃ exert synergistic anti-wear and load-bearing effects via forming a stable transfer film on the friction interface. Experimental results confirm that the accelerated test is equivalent to full-life durability test. The presented method and optimized friction pair can effectively guide the development of high-performance ultrasonic motors.

Abstract: Increasingly stringent fire safety, environmental, and occupational health regulations have accelerated the development of sustainable fire-resistant materials. WEICs have gained attention as multifunctional passive fire protection systems due to their strong substrate adhesion, low volatile organic compound emissions, and environmentally compatible formulations. This review highlights recent advances in epoxy-based intumescent composite coatings, focusing on how formulation design and microstructural characteristics influence fire-protective performance. Key flame-retardant mechanisms, including thermal degradation, chemical transformation, and char expansion behaviour, are discussed within heterogeneous composite systems. Emphasis is placed on the synergistic interactions among acid sources, carbon-forming agents, and blowing agents, as well as on incorporating fillers and reinforcing phases to enhance thermal insulation and expansion stability. Emerging strategies involving nanostructured reinforcements, bio-based additives, and hybrid composites are also evaluated for their potential to enhance char strength, mechanical durability, and heat resistance. Despite notable progress, challenges remain in long-term durability, interfacial compatibility, economic feasibility, and large-scale implementation, highlighting the need for halogen-free, low-toxicity intumescent coating technologies.