Search Results (7,553)

Major vibrational spectroscopy studies have focused on the preparation of chromium coatings via chemical processes (conversion coatings), and few studies have focused on electrochemical processes (electrodeposition). Initially, the chemical precursors were hexavalent chromium salts, but these compounds are now replaced by less toxic trivalent ions. There is a profound understanding of the process when vibrational spectroscopy is used in combination with other techniques. This is the case for chromium(VI) conversion coatings, and the results of several techniques, such as synchrotron infrared microspectroscopy, have made it possible to understand the structure of the two-layer coating and the chemical composition of each layer. Vibrational spectroscopy confirmed the mechanism for coating formation, in which ferricyanide was a redox mediator. In addition, vibrational spectroscopy was effective in determining the mechanism of corrosion resistance of the coatings. Conversely, there are very few studies on the electrodeposition of trivalent chromium ions, and the mechanics of electrodeposition are unknown. To simplify the use of spectroscopy, spectra of potassium dichromate and chromium(III) sulfate are presented as references for coating studies, and a compilation of $\mathrm{C}\mathrm{r}\left(\mathrm{I}\mathrm{I}\mathrm{I}\right)-\mathrm{O}$ and $\mathrm{C}\mathrm{r}\left(\mathrm{V}\mathrm{I}\right)-\mathrm{O}$ vibrational modes is provided to facilitate band assignment. Our review highlights that spectroscopic techniques have been insufficiently applied in this field; however, the results of vibrational spectroscopy accelerate the transition to safer Cr(III) technology. Full article

Bronze materials are indispensable across numerous industries for enhancing the durability and performance of components, primarily due to their excellent tribological properties, corrosion resistance, and machinability. This study investigates the impact of different atmospheric conditions on the properties of WAAM (wire arc additive manufacturing) cladded bronze coatings on 09G2S steel substrate. Specifically, the research examines how varying atmospheres—including ambient air (N₂/O₂, no shielding gas), pure argon (Ar), carbon dioxide (CO₂), and 82% Ar + 18% CO₂ (Ar/CO₂) mixture—influence coating defectiveness (porosity, cracks, non-uniformity), wettability (manifested as uniform layer formation and strong adhesion), and the extent of intergranular penetration (IGP), leading to the formation of characteristic infiltrated cracks or “bronze whiskers”. Modern investigative techniques such as optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) were employed for comprehensive material characterization. Microhardness testing was also carried out to evaluate and confirm the homogeneity of the coating structure. The findings revealed that the bronze coatings primarily consisted of a dominant, highly textured FCC α-Cu phase and a minor BCC α-Fe phase, with Rietveld refinement quantifying a α-Fe volume fraction of ~5%, lattice parameters of a = 0.3616 nm for α-Cu and a = 0.2869 nm for α-Fe, and a modest microstrain of 0.001. The bronze coating deposited under a pure Ar atmosphere exhibited superior performance, characterized by excellent wettability, a uniform, near-defect-free structure with minimal porosity and cracks, and significantly suppressed formation of bronze whiskers, both in quantity and size. Conversely, the coating deposited without a protective atmosphere demonstrated the highest degree of defectiveness, including agglomerated pores and cracks, leading to an uneven interface and extensive whisker growth of varied morphologies. Microhardness tests confirmed that while the Ar-atmosphere coating displayed the lowest hardness (~130 HV_0.1), it maintained consistent values across the entire analyzed area, indicating structural homogeneity. These results underscore the critical role of atmosphere selection in WAAM processing for achieving high-quality bronze coatings with enhanced interfacial integrity and functional performance. Full article

Powder coating, as a promising coating material, has attracted widespread attention due to its convenient construction and being a green option, promoting environmental protection. However, the existence of defects such as insufficient leveling and poor mechanical properties of the coating during the coating process limits the further expansion of its application fields. Therefore, for this article, powder coatings with high leveling performance were prepared by composite modification of nylon 12 (PA-12) resin with polyacrylates and ethylene-α-olefin copolymers (POE). The introduction of modified polyacrylates reduces the surface tension of nylon chains, enhancing melt flowability during curing and making the coating surface smooth. Furthermore, by introducing POE, the flexibility of the powder coating was improved, and its fracture elongation increased from 59% for pure PA-12 to a maximum of 234%. This study provides an effective method for the modification of nylon powder coatings and offers new insights into their use in high-performance coating applications. Full article

In this study, the effects of different Mn content and heat treatment on the microstructure and properties of CoCrFeNiTi coatings by laser cladding technology were investigated. Scanning electron microscopy, energy-dispersive spectrometry, and X-ray diffraction were used to analyze the structure and composition. The hardness and wear resistance were tested by a microhardness tester and a friction-wear tester. The results show that there are many intermetallic compounds rich in Ti and Ni between the grains. As the Mn content increases, the coating gradually transitions from a dual-phase structure of BCC and FCC to a single FCC structure. The hardness of the coating decreases gradually with the increase in Mn content due to the change in the phase structure, while the friction coefficient decreases slightly at first and then increases significantly. The main wear mechanisms of the coating are adhesive wear and abrasive wear. After heat treatment at 600 °C, petal-like Laves precipitates appear. The average microhardness of CoCrFeNiTi coatings after heat treatment is lower than before treatment, and the friction coefficient is higher than before treatment. The average microhardness of the coating increases slightly with the increase in the treatment temperature. The average friction coefficient of the coating obtained after heat treatment at 600 °C is only 0.5941 because of its uniform microstructure. Therefore, it is reduced by approximately 15% compared with the base metal. Full article

Sexually transmitted infections, notably herpes simplex virus, remain significant global health concerns. Localized delivery systems that provide sustained antiviral activity at mucosal surfaces offer an attractive alternative to systemic therapies. In this study, we developed electrohydrodynamically deposited coatings utilizing a covalent acyclovir–poly (lactic-co-glycolic acid) (ACV–PLGA) conjugate for potential antiviral functionalization of medical devices. The ACV–PLGA prodrug was synthesized via drug-initiated ring-opening polymerization, yielding a copolymer characterized by FTIR, NMR, GPC, and DSC, with controlled drug loading and biodegradable properties. Systematic optimization of electrospinning and electrospraying parameters enabled the fabrication of both particulate and nanofibrous coatings on silicone ring models. Morphological analysis by SEM demonstrated that polymer concentration, solvent composition, and applied voltage critically governed coating architecture, ranging from microparticle layers to uniform bead-free fibers. In vitro studies revealed morphology-dependent degradation profiles and sustained release of ACV over 56 days. This integrated approach combining covalent prodrug synthesis with tunable electrohydrodynamic deposition offers a promising strategy for long-acting local antiviral prophylaxis via functionalized medical surfaces. Full article

Polyvinyl chloride (PVC) is a widely used polymer in composite systems due to its versatility and processability, with growing use in advanced engineering applications. This study presents the formulation, processing optimisation, and detailed characterisation of a hot-dip PVC-based plastisol composite coating developed for electrical insulation in electric vehicle (EV) battery systems. A series of plastisol formulations with varying filler contents were prepared and applied via dip-coating at withdrawal speeds of 5, 10, and 15 mm s⁻¹. The 5 mm s⁻¹ withdrawal speed resulted in the most uniform coatings with thicknesses of 890–2100 µm. Mechanical testing showed that lower filler content significantly improved performance: Group 1 (lowest filler) exhibited the highest tensile strength (11.9 N mm⁻²), elongation at break (465%), tear strength (92 N mm⁻¹), and abrasion resistance. SEM and EDX analyses confirmed more homogeneous filler dispersion in Group 1, while FTIR spectra indicated stronger polymer–plasticiser interactions. Contact-angle measurements showed an increase of ${38}^{\circ }$ in low-filler samples, indicating enhanced surface hydrophobicity. Furthermore, Group 1 coatings demonstrated superior dielectric strength (22.1 kV mm⁻¹) and excellent corrosion resistance, maintaining integrity for over 2000 h in salt-spray testing. These findings highlight the importance of filler optimisation in balancing mechanical, electrical, and environmental performance. The proposed PVC-based composite coating offers a durable, cost-effective solution for next-generation EV battery insulation systems and has potential applicability in other high-performance engineering applications. Full article

In recent years, wine producers have increasingly experimented with ancient fermentation and ageing techniques, such as the use of ceramic containers or pitch-coated amphorae. Despite growing interest in these traditional practices, few studies have investigated the chemical composition of the resulting wines. This is the first study that characterises pine pitch, historically used as a coating material, and evaluates the impact of pitched pottery vessels on the winemaking process and wine composition using a foodomics approach. Vinification was carried out in both pitch-coated and uncoated (control) clay containers. Chemical differences between must and wine produced in pitched and unpitched vessels were assessed using targeted and untargeted ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS). Compared to the control, must and wine from the pitch-coated vessels had higher concentrations of many polyphenols such as anthocyanins, coumaric acid and tartaric acid, while procyanidins were present in significantly lower amounts. These findings reveal that pitch-coated ceramic vessels significantly influence wine composition, offering a first step toward deeper investigations into how fermentation environments shape metabolite profiles. This knowledge not only enhances our understanding of traditional practices but also opens new avenues for innovation in contemporary oenology. Full article

Omniphobic membranes have gained extensive attention for mitigating membrane wetting in robust membrane separation owing to the super-repulsion toward water and oil. In this study, a Teflon/PAI composite membrane with omniphobic characteristics was prepared by a vacuum-assisted dip-coating strategy on the PAI hollow fiber membrane. A series of characterizations on morphological structure, surface chemical composition, wettability, permeability, mechanical properties, and stability were systematically investigated for pristine PAI and Teflon/PAI composite membranes. Subsequently, the experiment was conducted to explore the oil–gas separation performance of membranes, with standard transformer oil containing dissolved gas as the feed. The results showed that the Teflon AF2400 functional layer was modified, and C-F covalent bonds were introduced on the composite membrane surface. The Teflon/PAI composite membrane exhibited excellent contact angles of 156.3 ± 1.8° and 123.0 ± 2.5° toward DI water and mineral insulating oil, respectively, indicating omniphobicity. After modification, the membrane tensile stress at break increased by 23.0% and the mechanical performance of the composite membrane was significantly improved. In addition, the Teflon/PAI composite membrane presented satisfactory thermal and ultrasonic stability. Compared to the previous membranes, the Teflon/PAI composite membrane presented a thinner Teflon AF2400 separation layer. Furthermore, the omniphobic membrane demonstrated anti-wetting performance by reaching the dynamic equilibrium within 2 h for the dissolved gases separated from the insulating oil. This suggests an omniphobic membrane as a promising alternative for oil–gas separation in monitoring the operating condition of oil-filled electrical equipment online. Full article

Laser cladding is an essential method for strengthening and restoring component surfaces. To increase its efficacy and provide a reliable surface treatment technique, it is necessary to optimize process parameters, enhance material adhesion, and guarantee high-quality, reliable coatings. These measures help to extend the lifespan of components. In this study, the surfaces of AISI 904L stainless steel samples were cladded to prepare various Co-based composite coatings with single and multiple layers reinforced with WC–CoCr–Ni powder. The phases within the newly developed layers were investigated using X-ray Diffraction (XRD), while the microstructure was examined using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX). Further tests were performed to assess the hardness, wear resistance and corrosion performance of the deposited coatings. Analyzing and comparing the coatings, it was observed that the coating performance increased with increasing thickness and generally due to a lower amount of Fe present within the microstructure. Full article

In response to the problem of high energy consumption caused by inefficient temperature control of energy storage aggregates in traditional building envelope structures, this study developed a decanoic acid–stearic acid composite phase-change ceramsite aggregate to improve the thermal performance of buildings and promote the utilization of solid waste resources. Based on the theory of minimum melting, composite phase-change materials were screened through thermodynamic models. The capric acid–stearic acid (CA-SA) melt system, whose theoretical phase-transition temperature falls within the building indoor thermal environment control range (18–26 °C), was preferred as the experimental object of this study, and its characteristics were verified through step cooling curves and thermal property tests. Subsequently, the ceramsite adsorption process was optimized, and the encapsulation process was studied. Finally, the encapsulation performance was evaluated through thermal stability and stirring crushing rate tests. The results showed that the phase-transition temperature of the decanoic acid–stearic acid melt system was 24.83 °C, which accurately matched the indoor thermal environment control requirements. The ceramsite particles treated by a physical vibrating screen can reach equilibrium after 30 min of adsorption at room temperature and pressure, which is both efficient and economical. The encapsulation layer of sludge biochar cement slurry with a water–cement ratio of 0.5 and a biochar content of 3% has both thermal conductivity and encapsulation integrity. The thermal stability test showed that the percentage of leakage of sludge biochar cement slurry and epoxy resin encapsulated aggregates was 0%, and the thermal stability rating was “very stable”. However, the percentage of leakage of unencapsulated and spray-coated encapsulated aggregates was as high as 193% and 40%, respectively. The results of the mixing and crushing rate test show that although the mixing and crushing rate of sludge biochar cement slurry encapsulation is slightly higher, its production cost is much lower than that of epoxy resin, and it is also environmentally friendly. This study improves the thermal performance of buildings by using composite phase-change ceramsite aggregate, and simultaneously realizes the resource utilization of sludge biochar, providing a solution for building energy saving and efficiency that combines environmental and engineering value. Full article

Surface coatings have proven highly effective in addressing the critical challenges of friction, wear, and corrosion on steel substrates, which are responsible for over 80% of mechanical failures in industrial applications. Recent research highlights that advanced coatings—such as ceramic carbides/nitrides, high-entropy alloys, and metal-matrix composites—significantly enhance hardness, wear resistance, and environmental durability through mechanisms including protective oxide film formation, solid lubrication, and microstructural refinement. Moreover, these coatings exhibit robust performance under combined tribological-corrosive (tribocorrosion) conditions, where synergistic interactions often accelerate material degradation. Key developments include multilayer and composite architectures that balance hardness with toughness, self-lubricating coatings capable of in situ lubricant release, and active or self-healing systems for sustained corrosion inhibition. Despite these advances, challenges remain in predicting coating lifetime under multifield service conditions and optimizing interfacial adhesion to prevent delamination. Future efforts should prioritize multifunctional coating designs, improved tribocorrosion models, and the integration of sustainable materials and AI-driven process optimization. This review consolidates these insights to support the development of next-generation coatings for extending the service life of steel components across demanding sectors such as marine, aerospace, and energy systems. Full article

This article investigates the anticorrosive properties of Zr-ZrN coatings, including Zr-(Zr,Hf)N, Zr-(Zr,Ti)N, Zr,Hf-(Zr,Hf,Nb)N, and Zr,Nb-(Zr,Nb)N, deposited on AISI 321 stainless steel substrates. The hardness and elasticity modulus of these coatings, as well as their scratch test strength, were measured. Corrosion current densities were calculated using the polarisation resistance method and by extrapolating the linear sections of the cathodic and anodic curves under electrode polarisation. The structure and composition of the sample surfaces were analysed by transmission electron microscopy. Notably, the nitride coatings reduced the corrosion current density in a 3% aqueous NaCl solution at 25 °C by more than 10 times, from 6.96 for the uncoated substrate to 0.17 μA/cm² for the Zr-(Zr,Ti)N-coated sample. The addition of Ti nitride to Zr-ZrN led to the most significant decrease in the corrosion current density. However, the introduction of Nb caused an increase in the corrosion rate and a decrease in the polarisation resistance, and Hf did not affect the corrosion-protective properties of the studied nitride coatings. Full article

Aqueous zinc-ion batteries (AZIBs) have attracted considerable attention due to their intrinsic safety, low cost, and environmental friendliness. However, drastic volume expansion, sluggish reaction kinetics, and the insufficient structural stability of electrode materials still remain key challenges. In this work, a cascade structure-guided electron transport strategy was used to construct a vanadium nitride@carbon nanosheet/carbon nanofiber (VN@CNS/CNF) composite as a high-performance cathode for AZIBs. In this rationally engineered architecture, carbon-coated VN nanoparticles are uniformly anchored on a conductive carbon nanofiber network, forming a multidimensional interconnected structure that enables fast electron/ion transport and robust mechanical stability. The carbon shell effectively alleviates volume expansion and prevents VN nanoparticle agglomeration, while the continuous carbon fiber backbone reduces charge transfer resistance and enhances reaction kinetics. Benefiting from this synergistic structural design, the VN@CNS/CNF electrode delivers a high specific capacity of 564 mAh g⁻¹ at 0.1 A g⁻¹, maintains 99% capacity retention after 50 cycles, and retains 280 mAh g⁻¹ even at 8 A g⁻¹ after prolonged cycling. This study provides a new structural engineering strategy for vanadium nitride-based electrodes and provides strategic guidance for the development of fast-charging, durable aqueous zinc-ion batteries. Full article

Cold-spray additive manufacturing (CSAM) is an emerging solid-state deposition technology that effectively mitigates common defects associated with conventional thermal processes, such as oxidation, phase transformation, and residual stresses. In this study, copper–titanium (Cu-Ti) composite coatings were fabricated via high-pressure CSAM using mixed powders with Ti contents of 3, 6, and 10 wt.%. The influence of Ti content and post-heat treatment (350–400 °C) on the tensile properties of the composites was systematically investigated. The results indicate that the ultimate tensile strength (UTS) remained consistently within the range of 265–285 MPa under all conditions, showing only a mild positive correlation with Ti content. In contrast, ductility was significantly influenced by Ti addition, with elongation decreasing markedly as the Ti content increased. Notably, the composite with 3 wt.% Ti heat-treated at 400 °C exhibited a well-balanced combination of tensile strength (270 MPa) and ductility (20% elongation). These findings demonstrate that CSAM-fabricated Cu-Ti composites possess attractive mechanical properties, which can be tailored through Ti content and heat treatment. Full article

Marine engineering equipment operates under extreme conditions such as high salinity, humidity, and flow velocity during marine resource exploration. These harsh environments impose strict requirements on surface performance, especially in terms of wear and corrosion resistance. Wear-resistant coatings are increasingly regarded as a crucial surface engineering approach to mitigate multi-mechanism degradation and improve the long-term reliability of marine equipment. In this review, the typical wear mechanisms in marine environments are systematically analyzed. Corresponding to different service scenarios, the main categories of coating materials, such as metal matrix composite coatings, cermet coatings, functionally graded coatings, and nanolayered coatings are summarized in terms of their structure and performance characteristics. Furthermore, mainstream fabrication techniques, including high-velocity oxy-fuel (HVOF), high-velocity air-fuel (HVAF), laser cladding, cold spray, and physical/chemical vapor deposition (PVD/CVD), are reviewed with respect to their influence on coating micro-structure and properties. Standardized evaluation methods for coating performance are also discussed. Finally, the current research challenges are identified, and future development trends are outlined, with an emphasis on multifunctional, intelligent, and environmentally friendly coating systems. This work aims to provide a systematic reference and theoretical basis for the design and application of wear-resistant coatings in marine environments. Full article