This study clarifies how pre-oxidation enhances the high temperature durability of MoSi2 ceramic coatings above 1700 degrees C. After pre-oxidation at 1700 degrees C for 30 min, the coatings showed an oxidation life of 6.8 h at 1800 degrees C, with an upper anti-oxidation temperature limit of 1825 degrees C, and 294 thermal shock cycles from room temperature to 1800 degrees C. The treatment produces a continuous and dense 14.24 mu m SiO2 film that retains its protective function even when molten at 1800 degrees C, effectively blocking oxygen diffusion and compensating for SiO2 volatilization. At 1825 degrees C, decreased SiO2 viscosity combined with thermal stress leads to film cracking and rapid failure. Oxidation failure at 1800 degrees C results from the phase transformation of Mo5Si3 to Mo3Si and MoO3 volatilization, while thermal shock failure arises from the coupling of thermal and phase-transformation stresses, together with MoO3, which jointly induce the propagation of microcracks to the substrate.

To enhance the surface hardness and wear resistance of copper alloy workpieces, a Cu-Ni-W-Si gradient coating was fabricated on a Cu-Cr-Zr alloy substrate using coaxial powder-feeding laser cladding technology. Employing surface macroscopic morphology, flaw detection results, and cross-sectional microstructure as evaluation methods, along with the coating's surface microhardness as a performance indicator, orthogonal experiments were sequentially conducted on the laser cladding process parameters for the Cu-Ni-10(W,Si) bottom layer and the Cu-Ni-20(W,Si) top layer. The optimized process parameters were identified as follows: a laser power of 4500 W (5000 W for the top layer), a scanning speed of 30 mm/s (60 mm/s for the top layer), and a scanning step of 2 mm. Subsequently, the phase composition and microstructure of the Cu-Ni-W-Si gradient coating were analyzed, and the microhardness distribution as well as the room-temperature friction and wear performance were evaluated. The results show that the coating achieves a hardness of 417 HV, which is 5.8 times higher than that of the substrate, and exhibits a wear rate of 3.52 × 10-4 mm3/Nm, corresponding to 49.1% of the substrate's wear rate. The excellent performance of the coating is attributed to the favorable gradient metallurgical bonding between the coating and the substrate, as well as the presence of finely dispersed WSi2 high-hardness wear-resistant phases within the coating.

To address the surface wear issues of tungsten alloys in die-casting mold applications-where low hardness coupled with severe service conditions involving high-pressure impact from molten metal, thermal cycling, and component counter-friction-this study employed three techniques: laser cladding, plasma spraying, and vacuum surface carburization. Three distinct strengthening coatings were prepared on a tungsten heavy alloy (WHA) substrate. X-ray diffraction (XRD), scanning electron microscopy (SEM), a Vickers hardness tester, and block-on-ring friction and wear tests were employed to characterize the phase composition, microstructure, hardness, and wear resistance of the coatings. The results indicate that all three coatings significantly enhanced the hardness of the substrate, albeit through different strengthening mechanisms. The hardness increase in the laser-clad coating is attributed to the combined strengthening effect of rapid solidification-induced fine grains and dispersed WC particles. The enhanced hardness of the plasma-sprayed coating is due to the intrinsic hardness of WC and its dense layered structure. The carburized layer exhibits the highest hardness, resulting from the continuous WC phase formed via in situ reaction and an interface-free gradient transition with the substrate, which eliminates interfacial weak zones. Under loads of 50 N and 100 N, the plasma-sprayed coating demonstrated the best wear resistance, with wear volumes of 0.16% and 0.18% of that of the substrate, and wear depths of 4.57% and 3.50% of that of the substrate, respectively. It also exhibited the optimal load adaptability, making it a preferred solution for surface strengthening of tungsten alloy die-casting molds.

A combination of single factor and Box-Behnken response surface method was employed to optimize the impurity removal process during the evaporation crystallization of ammonium tungstate solution to prepare ammonium paratungstate (APT) with higher purity. Firstly, to reduce the total content of four impurities (Na, K, S and Mo) in APT, the preferred range of crystallization temperature, stirring speed and initial concentration of ammonium tungstate solution was preliminarily determined by single factor method. Secondly, the impurity removal process during the evaporation crystallization of APT was further optimized by Box-Behnken response surface method, and the interactive effects of three factors on the total amount of four impurities in APT was studied. The results show that the order of influence of three factors on the total content of four impurities is as follows: initial concentration of ammonium tungstate solution>evaporation temperature>stirring speed. The optimum process conditions are an evaporation temperature of 94 degrees C, a stirring speed of 1.25 m/s, and an initial ammonium tungstate concentration of 73 g/L. Under the experimental conditions, the total content of four impurities in the prepared APT is reduced to 39.351 mg/L, which corresponds to a relative error of merely 4.110% compared to the optimal prediction value of the response surface method model. Consequently, the purity of APT reaches 4N level. The generated APT crystal is a columnar cuboid morphology with a small amount of broken crystals. The layered structure is obvious, the particle size distribution is uniform, and the grain refinement is obvious.

This study investigated the effects of deep cryogenic treatment(DCT)on hot isostatic pressed(HIP)beryllium for inertial devices,focusing on residual stress,microstructure,tensile properties,and dimensional stability.The findings revealed that during DCT,residual stress in beryllium increased gradually due to non-uniform volumetric contraction and mismatch stress,reaching a 59.9%increase from initial levels after 200 h of DCT.DCT led to significant grain refinement and an increase in dislocation density.In 200 h DCT-treated beryllium,geometric necessary dislocation(GND)density increased 17.9%,grain size decreased 12.3%,and therefore yield strength and tensile strength improved by 4.2%and 5.6%,respectively.The dimensional stability of HIP beryllium was significantly enhanced by DCT,and the improvement tended to increase with the duration of DCT.The cumulative size changes of beryllium after 200 h of DCT during both cold exposure and cold cycling decreased significantly by 86%and 50%,respectively,compared to those of HIP beryllium.Furthermore,the residual tensile strength and retention rate increased by 12.5%and 5.5%,respectively,after undergoing room-temperature creep at 100 MPa for 1000 h.

To address the escalating demand for ultra-high-purity tungsten in advanced applications such as semiconductor targets and nuclear-grade shielding, this study develops a novel integrated process combining thermal decomposition, ammonia dissolution, and segmented evaporative crystallization. Initially, optimal parameters for the thermal decomposition and ammonia dissolution stages were identified through systematic optimization. A key innovation lies in independently regulating nucleation and crystal growth during ammonium paratungstate (APT) crystallization, which effectively overcomes the limitation of conventional methods requiring multiple crystallization cycles to attain high purity. Experimental results demonstrated that under optimized conditions—thermal decomposition at ~280°C and ammonia dissolution at 90°C—high-purity APT (4N5 grade, total impurities < 50 ppm) was achieved in a single crystallization cycle. Furthermore, under segmented crystallization conditions (nucleation at 80°C with a stirring speed of 1.26 m/s and growth at 90°C with a stirring speed of 1.09 m/s), the product exhibited an average particle size of 34.43 μm and a direct recovery efficiency of 73.1%. By suppressing burst nucleation and reducing impurity adsorption, this process provides a critical technological pathway for large-scale production of ultra-high-purity tungsten materials.

GH3039 nickel-based alloy, as a key material for thermocouple protection tubes, is susceptible to wear and oxidation failure in high-temperature kiln environment. To address this, boronized, chromized and borochromized coatings were prepared on GH3039 substrate, and the friction-wear properties and high-temperature oxidation resistance of both the substrate and the coatings were systematically characterized. The results show that the borochromized coating, benefiting from the synergistic effect of its relatively high surface hardness and the boric acid lubricating film formed during the wear process, reduces the wear rate by 84.07% (to 1.44 × 10-5 mm3·N-1·m-1). Meanwhile, it exhibits the optimal oxidation resistance due to its dense Cr-rich layer, which can inhibit oxygen diffusion and supply chromium for protective Cr2O3 film. After 100 h of oxidation at 950 °C, its oxidation weight gain is reduced by 78.68% compared with the boronized sample (to 1.20 mg/cm2).

To address the escalating demand for ultra-high-purity tungsten in advanced applications such as semiconductor targets and nuclear-grade shielding, this study synergistically coupled the processes of thermal decomposition, ammonia dissolution, and segmented evaporation crystallization. The optimal parameters for the thermal decomposition and ammonia dissolution stages were subsequently identified through systematic optimization. By independently regulating the nucleation and crystal growth processes during the crystallization of ammonium paratungstate (APT), the limitation of traditional methods, which require multiple crystallization cycles to achieve high purity, is effectively overcome. Experimental results demonstrated that under optimized conditions—thermal decomposition at ~280 °C and ammonia dissolution at 90 °C—high-purity APT (4N5 grade, total impurities < 50 ppm) was achieved in a single crystallization cycle. Furthermore, under segmented crystallization conditions (nucleation at 80 °C with a stirring speed of 1.26 m/s and growth at 90 °C with a stirring speed of 1.09 m/s), the product exhibited an average particle size of 34.43 μm and a direct recovery efficiency of 73.1%. By suppressing burst nucleation and reducing impurity adsorption, this process provides a critical technological pathway for large-scale production of ultra-high-purity tungsten materials.

High-reflectivity metallic films on aluminum substrates are crucial in advanced aerospace and military applications due to their excellent reflectivity and workability. In order to further improve the reflectivity and thermal stability of films, this study investigated the deposition of AgInCux (x = 1, 3, and 5 wt.%) films on Al 6061 alloy substrates using magnetron sputtering, exploring the impact of deposition parameters and composition on their optical properties and thermal stability. Increased copper content improved thermal stability, while it compromised reflectivity. Additionally, increasing deposition power and time initially enhanced reflectivity, but beyond an optimal point, it decreased. Therefore, the AgInCu films deposited at 30 W for 2 min exhibited the highest reflectivity of 99.8% in the near-infrared range, making them promising candidates for reflective films in next-generation optical applications.

Abstract As a potential substitute for traditional nonaqueous organic electrolytes, polymer‐based solid‐state electrolytes (SSEs) have the advantages of high safety, flexibility, low density, and easy processing. In contrast, they still face challenges, such as low room‐temperature ionic conductivity, narrow electrochemical windows, and poor mechanical strength. To realize the practical application of all‐solid‐state alkali metal ion batteries, there has been a lot of research on modifying the chemical composition or structure of polymer‐based SSEs. In this review, the transport mechanism of alkali metal ions in polymer SSEs is briefly introduced. We systematically summarize the recent strategies to improve polymer‐based SSEs, which have been validated in lithium‐ion batteries and sodium‐ion batteries, including lamellar electrolyte structure, dual salts hybridization, oriented filler alignment, and so on. Then, taking the unique properties of potassium metal and potassium ions into consideration, the feasibility of potassium‐ion batteries for practical use enabled by these novel modification methods is discussed.

The high-temperature oxidation susceptibility of tantalum-based alloys severely limits their engineering applications in elevated-temperature environments. In this study, a Yb2O3-modified MoSi2 composite ceramic coating was successfully fabricated on a tantalum substrate through a two-step process combining slurry sintering and embedded siliconization, with systematic investigation of its ultra-high-temperature oxidation resistance and failure mechanisms. The ceramic coating exhibits a gradient structure comprising a Yb2O3-MoSi2 main layer, a TaSi2 diffusion layer, and a Ta5Si3 transition layer. Under ultra-high-temperature oxidation at 1800 degrees C, the ceramic coating demonstrates an effective protection duration of 5.5 h. The continuous SiO2 glass film formed synergistically inhibits oxygen permeation with Yb2Si2O7/Yb2SiO5 silicates. Yb3+ stabilizes the SiO2 network structure by reducing non-bridging oxygen content, thereby enhancing oxide film viscosity and impeding oxygen diffusion. This research provides new insights into the compositional design and performance optimization of ultra-high-temperature protective ceramic coatings, advancing the application of tantalum-based materials in aerospace and energy-related fields.

Severe polysulfide shuttling and sluggish redox kinetics critically hinder lithium–sulfur (Li-S) battery commercialization. In this study, a multifunctional diatomite (DE)/TiO2/MoS2/N-doped carbon nanofiber (NCNF) composite separator was fabricated via hydrothermal synthesis, electrospinning, and carbonization. DE provides dual polysulfide suppression, encompassing microporous confinement and electrostatic repulsion. By integrating synergistic catalytic effects from TiO2 and MoS2 nanoparticles, which accelerate polysulfide conversion, and conductive NCNF networks, which facilitate rapid charge transfer, this hierarchical design achieves exceptional electrochemical performance: a 1245.6 mAh g−1 initial capacity at 0.5 C and 65.94% retention after 200 cycles. This work presents a rational multi-component engineering strategy to suppress shuttle effects in high-energy-density Li-S batteries.

Advancements in electrical components have intensified the challenges for copper alloy wear resistance and high-temperature performance in electrical applications. The surface coating preparation of Cu alloys is crucial for enhancing their lifespan and promoting sustainable resource development. This study explored the microstructure and properties of Cu-Cr-X coatings (X = Mo/W, Al2O3/TiO2) on Cu alloy substrates via laser-cladding to improve wear resistance and hardness, vital for electrical component reliability and switching capacity. The process involved adjusting the power and reinforcing the phase particle size. The results showed hardness > 110 HV for all coatings (vs. 67.4 HV for the substrate). Cu-Cr-W achieved the highest hardness at 179 HV due to W dispersion and WCr precipitate reinforcement. It also maintained a stable CoF and the lowest wear rate (1.87 mg/km), with a fivefold wear resistance compared to the substrate alone. Cu-Cr-W excelled in lifespan extension and material loss reduction due to superior hardness, wear resistance, and conductivity.

Although copper alloys exhibit high electrical conductivity, their inherent low hardness and insufficient wear resistance significantly limit their application in high-energy current-carrying friction scenarios. This study leverages the liquid-liquid phase separation (LLPS) characteristics of immiscible alloys during non-equilibrium solidification and employs laser cladding technology to fabricate Cu-36Cr-xW-4SiC (x = 0, 2, 5, 10 wt%) composite coatings on CuCrZr alloy. The research systematically investigated the influence of tungsten content on the heterogeneous microstructure and the regulation of electrical conductivity-wear properties of the coatings. The results indicate that the introduction of 2 wt% W suppresses the Stokes migration effect of the second phase in the molten pool, promoting the periodic layered distribution of Cr-rich hard phase regions along the edges of the molten pool. This forms a hardness gradient up to 12 times higher than the Cu-rich soft phase regions. This heterogeneous structure achieves decoupled optimization of conductivity (35.8 % IACS) and wear resistance (average volumetric wear rate of 0.158 mm3/km, an 88.5 % reduction compared to the substrate) through a synergistic mechanism of "hard phase bearing wear load-soft phase maintaining conductive pathways". The design strategy proposed in this study provides a new paradigm for the development of high-performance copper-based coatings.

This study investigated the micromechanical properties and creep behavior of hot isostatic pressed (HIP) beryllium after annealing, deep cryogenic (DCT), and thermal-cold cycling (TCC) treatments to analyze the stability effects of different stabilizing heat treatments, explore the underlying mechanisms, and advance the understanding of dimensional stability under micro-stress-strain conditions. Nanoindentation results revealed that annealing increased the elastic modulus by 5-23.4 %, DCT by 4.2-16.1 %, and TCC by 9.2-31.2 %, respectively. Compared to HIP beryllium, the creep strain rates were reduced by 5.7-12.7 % after DCT and by 2.6-9.7 % after TCC. The increased elastic modulus and decreased creep strain rates after different stabilizing heat treatments indicated an improvement in elastic deformation resistance and creep resistance, suggesting enhanced microscopic dimensional stability of beryllium to varying extents.

The study investigated the effects of thermal-cold cycling (TCC) treatment on the microstructure and mechanical properties of hot isostatic pressed (HIP) beryllium. The microstructure changes during TCC process, including alterations in grain boundary contents, grain size, geometrically necessary dislocations density, indicated that the reinforcing effect of -196 degrees C-200 degrees C and -196 degrees C-400 degrees C TCC was superior to that of -60 degrees C-200 degrees C and -100 degrees C-200 degrees C TCC. Consequently, compared to HIP beryllium and other TCC treated beryllium, the tensile strength and yield strength of beryllium after 16 TCCs of -196 degrees C-200 degrees C showed the greatest improvement, increasing from 430 MPa and 383 MPa to 450 MPa and 403 MPa, respectively. Similarly, the residual tensile strength and retention rate after room temperature creep at 100 MPa for 1000h increased from 360 MPa and 83.9 % to 393 MPa and 87.3 %, respectively.

In aerospace, BBC-Nb alloys confront notable challenges in thermal stability and toughness under cyclic fatigue at varying temperatures. Insufficient thermal stability and expedited coalescence of precipitates substantially accelerates the degradation of alloys at elevated temperatures. Here, a Nb alloy with impressive thermal stability and mechanical properties was designed using theoretical calculations and a two-step graded heat treatment process. The superlative properties of the Nb alloy are primarily associated with the NbC hierarchical structures, i.e., stable nanoparticles in Nb-BCC grains and discontinuous microparticles at grain boundaries (GBs). The hierarchical carbides configuration avoids continuous precipitation of carbides at GBs and preferential coarsening within the grains. The process involves precipitating ZrC nanoparticles at 1350 degrees C, then stabilizing NbC at 1800 degrees C by replacing Zr with Nb. Nb-FCC nanophases enveloping NbC prevent coarsening and have strong relationships with both NbC nanoparticles and matrix. The concept of fine-tuning NbC precipitation within grains and introducing NbC at GBs with a substitution method offers a strategy for high-strength, heat-resistant materials. (c) 2024 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Gel-polymer electrolytes offer a promising route toward safer and more stable sodium-ion batteries, but conventional polymer systems often suffer from low ionic conductivity and limited voltage stability. In this study, we developed composite GPEs by embedding methylammonium lead chloride (CH3NH3PbCl3, MPCl) into a UV-crosslinked ethoxylated trimethylolpropane triacrylate (ETPTA) matrix, with sodium alginate (SA) as an ionic conduction enhancer. Three types of membranes—GPE-P, GPE-El, and GPE-Eh—were synthesized and systematically compared. Among them, the high-MPCl formulation (GPE-Eh) exhibited the best performance, achieving a high ionic conductivity of 2.14 × 10−3 S·cm−1, a sodium-ion transference number of 0.66, and a wide electrochemical window of approximately 4.9 V vs. Na+/Na. In symmetric Na|GPE|Na cells, GPE-Eh enabled stable sodium plating/stripping for over 600 h with low polarization. In Na|GPE|NVP cells, it delivered a high capacity retention of ~79% after 500 cycles and recovered ~89% of its initial capacity after high-rate cycling. These findings demonstrate that the perovskite–polymer composite structure significantly improves ion transport, interfacial stability, and electrochemical durability, offering a viable path for the development of next-generation quasi-solid-state sodium-ion batteries.

The insufficient corrosion resistance and high interfacial contact resistance (ICR) of 316L stainless steel (316L SS) severely limit its application as bipolar plates (BPs) in proton exchange membrane fuel cells (PEMFCs). In this study, a graphite/carbon black/PVDF composite coating was first developed by hot rolling on the surface of 316L SS to enhance both corrosion resistance and conductivity. By incorporating 5 wt% polyaniline (PANI) as a corrosion inhibitor, the optimized RP5 coating exhibited further improvements in corrosion resistance. The potentiodynamic polarization tests revealed that the RP5 coating achieved a corrosion current density of 0.977 μA·cm−2, representing a two-orders of magnitude reduction compared to bare 316L SS (34.1 μA·cm−2). The coating also exhibits a satisfactory interfacial contact resistance (ICR) of 8.20 mΩ·cm2 at 1.5 MPa, meeting the U.S. Department of Energy (DOE) 2025 targets (<10 mΩ·cm2). Additionally, the RP5 coating exhibited superior hydrophobicity with a water contact angle of 96.5°, which is advantageous for water management within PEMFCs. The results confirm that the RP5 coating achieves an optimal balance between high conductivity, excellent corrosion resistance, and improved hydrophobicity, making it a promising solution for advancing PEMFC bipolar plates’ performance.

Sodium-ion batteries (SIBs) are considered the next-generation candidates for partially substituting for commercial lithium-ion batteries in future energy storage systems because of the abundant sodium/potassium reserves and these batteries’ cost-effectiveness and high safety. Gel polymer electrolytes (GPEs) have become a popular research focus due to their advantages in terms of safety and performance in research on quasi-solid-state sodium-ion batteries (QSSIBs). Building on previous studies that incorporated MOF fillers into polymer-based gel electrolytes, we propose a 3D sandwich structure in which MOF materials are first pressed into thin films and then coated and protected by polymer materials. Using this approach, we achieved an ion conductivity of 1.75 × 10−4 S cm−1 at room temperature and an ion transference number of 0.69. Solid-state sodium-ion batteries using this gel film electrolyte exhibited long cycling stability at a 2 C current density, retaining 75.2% of their specific capacity after 500 cycles.