Search Results (7,328)

By integrating cathodic arc evaporation (CAE) with magnetron sputtering (MS) or high-power impulse magnetron sputtering (HiPIMS), hard coatings with diverse multicomponent compositions can be fabricated. Depending on the deposition conditions, the coatings with nano-composite or nano-multilayered microstructures are produced. During the mixing deposition conditions, nano-composite coatings are fabricated, which can be tailored to possess combining properties of super hardness, low friction coefficient, and excellent thermal/chemical stability. For the deposition with larger rotating periods, layer-by-layer deposition was observed. By the nano-multilayered coating design, superior mechanical properties (hardness ≥ 35 GPa), modulated residual stresses, and enhanced high-temperature properties can be obtained. In addition, lubricious elements, low friction (friction coefficient < 0.4), and low wear (<10⁻⁵ mm³/N∙m) both at ambient temperature and high temperature can be realized. Among these coatings, some have been specifically designed to achieve outstanding cutting performance in high-speed cutting applications. Several nitride and oxide hard coatings, such as AlTiN, TiAlN/TiSiN, AlCrN/Cu, and AlCrO, were deposited using a hybrid industrial physical vapor deposition (PVD) coating system. The microstructure, mechanical properties, and cutting performance of these coatings will be discussed. Full article

Hopeite (Zn₃(PO₄)₂·4H₂O) coatings, fabricated via zinc phosphate chemical conversion (ZPCC), have attracted considerable interest in biomedical applications owing to their excellent corrosion resistance and biocompatibility. However, the influence of calcium nitrate (CN) on coating properties remains poorly understood. This study systematically investigates the effect of CN concentration on the microstructure and corrosion behavior of ZPCC coatings deposited on stainless steel (SS). The phase composition, surface morphology, and elemental distribution were characterized using X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS). Electrochemical corrosion performance was assessed via potentiodynamic polarization in a 0.9 wt.% NaCl solution. The results indicate that CN concentration critically influences coating morphology, with higher concentrations leading to reduced crystal size and increased coating mass. Notably, the coating prepared with 6 g/L CN exhibited a dense, uniform, and fine-grained microstructure, resulting in superior corrosion resistance. Additionally, the optimized coating demonstrated strong interfacial adhesion, with a shear strength of 10.05 ± 1.2 MPa. Full article

Fire retardancy and thermal management improvements in epoxy resins can critically impact their use in electronics for IoT and 5G devices. This study proposes a facile method to improve the fire retardancy and thermal properties of epoxy resins (EPs) by incorporating boron nitride nanoparticles (BNNPs) with boron polyol complex (BPC) to form an ionanofluid and explores the synergistic effect of polyelectrolytes with BN. The modified multifunctional additive BPC–BNNPs were then used for the functional modification of epoxy resin. Our detailed tests and analyses on these materials confirm that by adding 0.2 wt% of BNNPs in the EP–BPC–BN complex achieved a V-0 rating in the UL-94 vertical burning test. The resultant composite demonstrated that the modification of BN with the polyol complex imparted a low smoke and char formation in the modified epoxy composites. The current study shows that EP–BPC–BN complex has great potential as a thermal interface material for the thermal management of electronics or similar applications. The presented EP–BPC–BN composite can also be utilised as a fire-retardant coating, adhesive, and binding agent in the aerospace, transportation, and building industries. Full article

Hollow dendritic Na₄La₂(CO₃)₅ crystals doped with Sm³⁺ ions were synthesized with sodium carbonate using a hydrothermal method. The unique lifetime of Sm³⁺ enables the optical measurement of luminescent ion content. The X-ray diffraction spectrum indicates that the nanocrystals maintain structural stability with a hexagonal arrangement, even when the concentration of Sm³⁺ reaches 50 at.%. As the concentration of Sm³⁺ increases, the emission intensity of Na₄(La_1−xSm_x)₂(CO₃)₅ first rises and then falls. The maximum emission intensity of the fluorescent powder occurs at a Sm³⁺ concentration of 0.04. Beyond this concentration, concentration quenching takes place, primarily due to electric dipole–dipole interactions. Using an excitation wavelength of 404 nm and monitoring at 596 nm, the fluorescence lifetime of Na₄(La_1−xSm_x)₂(CO₃)₅ shows a strong dependence on Sm³⁺ concentration, which can be described by a precise equation. Over the range of Sm³⁺ concentrations from 0.005 to 1, the lifetime decreases from 3.126 ms to 0.023 ms. Therefore, optical monitoring of fluorescent powders is crucial for confirming the composition of coatings used in applications such as solid-state lighting and anti-counterfeiting, by utilizing the relationship between lifetime and doping concentration. Full article

Propolis is a substance produced by bees from the collection of plant resins, with a chemical composition that varies according to the available flora and region, and it has several biological activities. Stingless bee propolis is often produced in reduced amounts, posing a challenge to the study of their volatile compounds, as traditional hydrodistillation extraction would demand more raw propolis than available. These bees collect resins from various sources, resulting in a variable composition, so a standardized reproducible method is fundamental for their analysis. Headspace solid-phase microextraction (HS-SPME), associated with gas chromatography, appears to be an efficient alternative for the analysis of these volatiles. In this study, the GC-MS results of three types of SPME fibers were compared to those of extracts obtained by hydrodistillation to evaluate their efficiency in representing the composition of essential oils from (geo)propolis of different species. The extraction time and temperature were also standardized. Among the fibers tested, PDMS/DVB extracted the volatiles in a similar manner to the essential oil obtained by hydrodistillation for all the samples tested, indicating this to be the best choice of fiber coating for propolis volatile extraction and analysis. Full article

In this study, Ni-Co-Y₂O₃ composite coating was prepared by electrodeposition, and the effect of Y₂O₃ particle size on the microstructure and properties of the coating was investigated. The samples were analyzed by XRD, SEM, AFM, EDS, cyclic voltammetry, XPS, hardness, and corrosion resistance test. The results indicate that the diffraction peak of the coating prepared with 50 nm particles exhibits reduced intensity and broadening, whereas the coating prepared with 100 nm particles displays a sharper and more pronounced peak. The onset reduction potential and the performance of the reduction reaction are influenced by particle size. When the particle size is 50 nm, the reduction process is less favorable, with an onset reduction potential of −0.9 V; in contrast, when the particle size is 100 nm, the reduction occurs more readily, with an onset reduction potential of −0.8 V. XPS analysis reveals that the chemical environment of elements varies with particle size. Regarding hardness, the coating prepared by combining different Y₂O₃ particle sizes exhibits higher hardness compared to that prepared using a single particle size, which can be attributed to the synergistic effect. In terms of corrosion resistance, the coating prepared with 100 nm Y₂O₃ particles demonstrates superior corrosion resistance, whereas the coating prepared with mixed particle sizes shows reduced stability and is more susceptible to corrosion. The coating prepared by mixing Y₂O₃ with particle size of 50 nm and 100 nm has a small friction coefficient. In summary, the particle size of Y₂O₃ has a significant influence on the microstructure, hardness, and corrosion resistance of Ni-Co-Y₂O₃ composite coatings. Full article

A novel structure–functional-integrated particle featuring dual micromechanical interlocking property with resin matrix was constructed through surface modification of urchin-like serried hydroxyapatite (UHA) in this work, and the effect of this modification strategy on physicochemical and biological properties of dental resin composite was also investigated. A porous silica coating layer was anchored onto UHA surface via a simple template method in an oil−water biphase reaction system, and the coating time had a prominent effect on the coating thickness and morphology-structure of the particle. When these particles with different porous silica coating thickness were used as fillers for dental resin composite, results showed that UHA/PS5 (porous silica coating reaction time: 5 h) exhibited the optimal 3D urchin-like structure and a desirable porous silica coating thickness. Additionally, UHA/PS5 formed the best dual physical micromechanical interlocking structure when mixing with resin matrix, making the dental resin composites presented the desirable matrix/filler interfacial bonding, and the excellent physicochemical–biological properties, especially for flexural strength and water sorption-solubility. In vitro remineralization and cellular biological properties confirmed that the coating layer did not compromise their remineralization activity. The use of UHA/PSx provides a promising approach to develop strong, durable, and biocompatible DRCs. Full article

Over the last few decades, polymer composites have been rapidly making inroads in critical applications of electrical storage devices such as batteries and supercapacitors. Structural supercapacitor composites (SSCs) have emerged as multifunctional materials capable of storing energy while bearing mechanical loads, offering lightweight and compact solutions for energy systems. This study investigates the functionalization of Bisphenol A-based thermosetting polymers with ionic liquids, aiming to synthesize dual-functional structural electrolytes for SSC fabrication. A multifunctional sandwich structure was subsequently fabricated, in which the fabricated SSC served as the core layer, bonded between two structurally robust outer skins. The core layer was fabricated using carbon fibre layers coated with 10% graphene nanoplatelets (GNPs), while the skin layers contained 0.25% GNPs dispersed in the resin matrix. The developed device demonstrated stable operation up to 85 °C, achieving a specific capacitance of 57.28 mFcm⁻² and an energy density of 179 mWhm⁻² at room temperature. The performance doubled at 85 °C, maintaining excellent capacitance retentions across all experimented temperatures. The flexural strength of the developed sandwich SSC at elevated temperature (at 85 °C) was 71 MPa, which exceeds the minimum requirement for roofing sheets as specified in Australian building standard AS 4040.1 (Methods of testing sheet roof and wall cladding, Method 1: Resistance to concentrated loads). Finite element analysis (FEA) was performed using Abaqus CAE to evaluate structural integrity under mechanical loading and predict damage initiation zones under service conditions. The simulation was based on Hashin’s failure criteria and demonstrated reasonable accuracy. This research highlights the potential of multifunctional polymer composite systems in renewable energy infrastructure, offering a robust and energy-efficient material solution aligned with circular economy and sustainability goals. Full article

Lithium-ion batteries (LIBs) have garnered extensive application across various domains. However, frequent safety incidents associated with these LIBs have emerged as a significant impediment to their further advancement. Consequently, there is an urgent necessity to develop a novel fire extinguishing agent that possesses both rapid fire suppression and efficient cooling capabilities, thereby effectively mitigating the occurrence and propagation of fires in LIBs. This study pioneers the development of an adaptive thermosensitive microcapsule (TM) fire extinguishing agent synthesized via in situ polymerization. The TM encapsulates a ternary composite core—perfluorohexanone (C₆F₁₂O), heptafluorocyclopentane (C₅H₃F₇), and 2-bromo-3,3,3-trifluoropropene (2-BTP)—within a melamine–urea–formaldehyde (MUF) resin shell. The TM was prepared via in situ polymerization, combined with FE-SEM, FTIR, TG–DSC, and laser particle size analysis to verify that the TM had a uniform particle size and complete coating structure. The results demonstrate that the TM can effectively suppress the thermal runaway (TR) of LIBs through the synergistic effects of physical cooling, chemical suppression, and gas isolation. Specifically, the peak TR temperature of a single-cell LIB is reduced by 14.0 °C, and the heating rate is decreased by 0.17 °C/s. Additionally, TM successfully blocked the propagation of TR thereby preventing its spread in the dual-LIB module test. Limitations of single-component agents are overcome by this innovative system by leveraging the ternary core’s complementary functionalities, enabling autonomous TR suppression without external systems. Furthermore, the TM design integrates precise thermal responsiveness, environmental friendliness, and cost-effectiveness, offering a transformative safety solution for next-generation LIBs. Full article

In recent years, research into the synthesis of innovative biomaterials for prosthetic applications has been increasingly growing. In particular, there is a demand for biomaterials with an excellent biocompatibility that can interact with biological fluids. This study involved the development of new silica (SiO₂)-based composite materials using the sol–gel technique and functionalization with ferulic acid (FA), a natural phenolic compound renowned for its biological properties. The synthesis involved controlling the hydrolysis and condensation of tetraethyl orthosilicate (TEOS) in acidic and alcoholic environments to incorporate ferulic acid into the sol phase matrix at different weight compositions (5, 10, 15, and 20 wt%). Fourier transform infrared spectroscopy analyses (FTIR) confirmed the successful incorporation of the bioactive compound, and in vitro tests revealed a good cytocompatibility and controlled ferulic acid release over time. These results demonstrate that the developed material shows promise as a bioactive coating for orthopedic prostheses, improving bone integration and reducing undesirable post-operative phenomena. Full article

Recently, there has been increased interest in NASICON-type electrodes for sodium-ion batteries due to their unique combination of intercalation properties, low cost, and safety. However, their commercialization is hindered by the low electrical conductivity. One strategy to overcome this issue is to integrate NASICON materials with carbon additives. This study shows that carbon additives improve the sodium storage performance of a NASICON-type electrode in various ways, depending on the additives’ functional groups, texture, and conductivity properties. The proof-of-concept is based on a multi-electron phospho-sulphate electrode, NaFeVPO₄(SO₄)₂ (NFVPS) mixed with carbon black (C) and reduced graphene oxide (rGO). Carbon-coated samples are obtained via a simple ball milling procedure followed by thermal treatment in an argon flow. Sodium storage in the composites occurs through capacitive and Faradaic reactions. The Faradaic reaction is facilitated at the carbon black composite, while the capacitive reaction dominates for the rGO composite. NFVPS operates through two-electron reactions at 20 °C, while the increased temperatures favor the three-electron reaction. The rGO composite outperforms the carbon black composite in terms of cycling stability and rate capability at 20 and 40 °C. The role of the rGO and carbon black in electrochemical performance is discussed based on the different reactivity of hydroxyl/epoxide and carbonyl functional groups with the electrolyte salt, NaPF₆, and the solvent, polypropylene carbonate. Full article

The rapid dissipation of soft metal lubricants would deteriorate the self-lubricating properties of the coatings at elevated temperatures. In this study, the core-shell structured Mo@Ag@Ni particles were prepared via electroless plating to suppress the rapid dissipation of Ag and facilitate tribochemical reactions at high temperatures. The NiCrAlY-Mo@Ag@Ni composite coating was sprayed on the substrate of Inconel 718 alloy using atmospheric plasma spraying technology. The results of this study show that the structural design of Mo@Ag@Ni can enhance the bonding strength of the particle interface, resulting in a high microhardness of approximately 332.2 HV. During high-temperature friction tests, Mo@Ag@Ni can provide excellent tribological properties by promoting the silver molybdate formation on the worn surface. At 800 °C, the friction coefficient and wear rate are only about 0.32 and 1.58 × 10⁻⁵ mm³N⁻¹m⁻¹, respectively. Moreover, the Ni shell layer can inhibit the rapid diffusion of Ag and provide sufficient Ag₂O to maintain the continuity of Ag₂MoO₄ lubricating film, which endows the coating with a longer lubrication life. Over multi-thermal cycles, the friction coefficient and wear rate constantly maintain at about 0.3 and 2.5 × 10⁻⁵ mm³N⁻¹m⁻¹, respectively. Full article

Lithium–iron disulfide (Li-FeS₂) batteries are plagued by the polysulfide shuttle effect and cathode structural degradation, which significantly hinder their practical application. This study proposes a dual-strategy design that combines a polyacrylonitrile–carbon nanotube (PAN-CNT) composite cathode and a polyvinylidene fluoride (PVDF)-conductive carbon-coated separator to synergistically address these bottlenecks. The PAN-CNT binder establishes chemical anchoring between polyacrylonitrile and FeS₂, enhancing electronic conductivity and mitigating volume expansion. Specifically, the binder boosts the initial discharge capacity by 35% while alleviating the stress-induced pulverization associated with volume changes. Meanwhile, the PVDF-conductive carbon-coated separator enables effective polysulfide trapping via dipole–dipole interactions between PVDF’s polar C-F groups and Li₂S_x species while maintaining unobstructed ion transport with an ionic conductivity of 1.23 × 10⁻³ S cm⁻¹, achieving a Coulombic efficiency of 99.2%. The electrochemical results demonstrate that the dual-modified battery delivers a high initial discharge capacity of 650 mAh g⁻¹ at 0.5 C, with a capacity retention rate of 61.5% after 120 cycles, significantly outperforming the control group’s 47.5% retention rate. Scanning electron microscopy and electrochemical impedance spectroscopy confirm that this synergistic design suppresses polysulfide migration and enhances interfacial stability, reducing the charge transfer resistance from 26 Ω to 11 Ω. By integrating polymer-based functional materials, this work presents a scalable and cost-effective approach for developing high-energy-density Li-FeS₂ batteries, providing a practical pathway to overcome key challenges in their commercialization. Full article

Modeling the structure not only of whole metal products, but also of the protective coatings with which they are coated, brings a number of economic benefits through more resistant coatings and coatings that can be produced by simplifying manufacturing technology or reducing material consumption in the process. This paper presents the results of a study of dip metallization in zinc baths with Ti additions. Both steel and cast iron substrates were coated and similar results were obtained. The obtained coatings were subjected to SEM analysis with chemical composition studies, TEM characterization with selected area electron diffraction (SAED), and corrosion studies. Particle models of the elementary phases present in the zinc coating made with CaRine 3.0 software were presented and used for phase analysis. It emerged that coatings obtained in zinc baths with the addition of Ti are characterized by a more varied microstructure, the occurrence of phase separations to which Ti segregates, and higher corrosion resistance than classical zinc coatings. The higher corrosion resistance is prompted not only by the Ti content in the intermetallic phases, but also by the observed nanostructure favorably located in the alloy layer. Full article

To meet the growing demand for intelligent surfaces in furniture and interior design, this study developed thermochromic UV coatings for bleached poplar. While conventional UV coatings are valued for their ecofriendliness and rapid curing, their functionality remains limited; integrating thermochromic capability offers a highly promising solution. We examined how the combination of two microcapsule systems (UF@TS and UF@TS-R) influenced the performance of UV coatings on bleached poplar by applying a two-primer/two-topcoat protocol with varied microcapsule loadings to impart color-changing behavior. The effects were then analyzed from multiple perspectives—type, application layer, and concentration gradient—covering optical and mechanical properties as well as thermochromic response. Results indicated that the optimum performance was achieved when UF@TS was incorporated into the UV topcoat and UF@TS-R into the UV primer at specific mass concentrations. The resulting coating delivered temperature-responsive color variation, providing both theoretical and technical support for developing high-value-added UV finishes for wooden furniture and advancing the use of fast-growing timber in high-end applications. Full article