To enhance the oxidation resistance of Mo-based TZM alloy (Mo-0.5Ti-0.1Zr-0.02C, wt%), a novel MoSi₂-ZrB₂ composite coating was applied on the TZM substrate by a two-step process comprising the in situ reaction of Mo, Zr, and B₄C to form a ZrB₂-MoB pre-layer followed by pack siliconizing. The as-packed coating was composed of a multi-layer structure, consisting of a MoB diffusion layer, an MoSi₂-ZrB₂ inner layer, and an outer layer of mixture of MoSi₂ and Al₂O₃. The composite coating could provide excellent oxidation-resistant protection for the TZM alloy at 1600 °C. The oxidation kinetic curve of the composite coating followed the parabolic rule, and the weight gain of the coated sample after 20 h of oxidation at 1600 °C was only 5.24 mg/cm². During oxidation, a dense and continuous SiO₂-baed oxide scale embedded with ZrO₂ and ZrSiO₄ particles showing high thermal stability and low oxygen permeability could be formed on the surface of the coating by oxidation of MoSi₂ and ZrB₂, which could hinder the inward diffusion of oxygen at high temperatures. Concurrently, the MoB inner diffusion layer played an important role in hindering the diffusion of Si inward with regard to the TZM alloy and could retard the degradation of MoSi₂, which could also improve the long life of the coating.

To improve the oxidation resistance of Mo-based alloys, a novel (Mo,Hf)Si₂-Al₂O₃ composite coating was fabricated on a Mo-based alloy by the method of slurry sintering. The isothermal oxidation behavior of the coating was evaluated at 1400 °C. The microstructure evolution and phase composition of the coating before and after oxidation exposure were characterized. The anti-oxidant mechanism for the good performance of the composite coating during high-temperature oxidation was discussed. The coating had a double-layer structure consisting of a MoSi₂ inner layer and a (Mo,Hf)Si₂-Al₂O₃ outer composite layer. The composite coating could offer more than 40 h of oxidation-resistant protection at 1400 °C for the Mo-based alloy, and the final weight gain rate was only 6.03 mg/cm² after oxidation. A SiO₂-based oxide scale embedded with Al₂O₃, HfO₂, mullite, and HfSiO₄ was formed on the surface of the composite coating during oxidation. The composite oxide scale exhibited high thermal stability, low oxygen permeability, and enhanced thermal mismatch between oxide and coating layers, thus improving the oxidation resistance of the coating.

To improve the wear resistance of high-strength and high-conductivity Cu–Cr–Zr alloys in high-speed and heavy load friction environments, coatings including Ni–Cu, Ni–Cu-10(W,Si), Ni–Cu–10(Mo,W,Si), and Ni–Cu–15(Mo,W,Si) (with an atomic ratio of Mo,W to Si of 1:2) were prepared using coaxial powder-feeding laser cladding technology. The microstructure and wear performance of coatings were chiefly investigated. The results revealed that (Mo,W)Si₂ and MoNiSi phases are found in the Ni–Cu–10(Mo,W,Si) and Ni–Cu–15(Mo,W,Si) coating. WSi₂ phases are found in the Ni–Cu–10(W,Si) coating. The degree of grain refinement in Ni–Cu–10(Mo,W,Si) was greater than that of the Ni–Cu–10(W,Si) coating after the effect of Mo. The excellent wear resistance and micro-hardness of the Ni–Cu–15(Mo,W,Si) coating were attributed to the increase in its dispersion phase, which were approximately 34.72 mg/km and 428 HV, 27.1% and 590% higher than the Cu–Cr–Zr substrate, respectively. The existence of silicide plays an important role in grain refinement due to the promotion of nucleation and the inhibition of grain growth. In addition, the wear mechanism transformed from adhesive wear in the Ni–Cu coating with no silicides to abrasive wear in the Ni–Cu–15(Mo,W,Si) coating with high levels of silicides.

To solve the problem of silicide coatings on tantalum substrates failing due to elemental diffusion under high-temperature oxidation environments and to find diffusion barrier materials with excellent effects of impeding Si elemental spreading, TaB₂ and TaC coatings were prepared on tantalum substrates by the encapsulation and infiltration methods, respectively. Through orthogonal experimental analysis of the raw material powder ratio and pack cementation temperature, the best experimental parameters for the preparation of TaB₂ coatings were selected: powder ratio (NaF:B:Al₂O₃ = 2.5:1:96.5 (wt.%)) and pack cementation temperature (1050 °C). After diffusion treatment at 1200 °C for 2 h, the thickness change rate of the Si diffusion layer prepared using this process was 30.48%, which is lower than that of non-diffusion coating (36.39%). In addition, the physical and tissue morphological changes of TaC and TaB₂ coatings after siliconizing treatment and thermal diffusion treatment were compared. The results prove that TaB₂ is a more suitable candidate material for the diffusion barrier layer of silicide coatings on tantalum substrates.

The escalating demand for sustainable and high-performance energy storage systems has led to the exploration of alternative battery technologies for lithium-ion batteries. Sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) have emerged as promising candidates because of their abundant Na/K resources, inexpensive costs, and similar chemistries to lithium-ion batteries. However, inherent challenges, such as large ionic radii, sluggish kinetics, and serious volume expansion, necessitate the development of robust and efficient anode materials for SIBs and PIBs. Vanadium nitride has attracted increasing attention as a viable anode due to its high electronic conductivity and potential capacity. In this study, we report on a flexible electrode for SIBs and PIBs that creates binder-free anodes by synthesizing vanadium nitride nanoparticles grown directly on carbon fiber cloths (VN/CFC). The unique architecture and binder-free nature of this anode ensure a robust electrode–electrolyte interface and enhance its electron/ion transport kinetics. The results demonstrate that the material exhibits an outstanding specific discharge capacity of 227 mAh g⁻¹ after undergoing 1000 cycles at a current density of 2 A g⁻¹ for SIBs. An electrochemical analysis indicated that the excellent performance of the material is attributed to the bind-free structure of carbon fiber cloth and the fast kinetics of surface pseudo-capacitive contribution. Furthermore, the material continues to demonstrate an impressive performance, even for PIBs, with a specific discharge capacity of 125 mAh g⁻¹ after 1000 cycles at a current density of 1 A g⁻¹. This study provides a new perspective for designing and developing advanced binder-free anodes for the storage of sodium and potassium ions, paving the way for high-performance energy storage applications.

In this study, we developed composite Fe-Cr-V-C coatings by plasma transferred-arc (PTA) powder surfacing on a 42CrMo steel substrate. The effects of arc current and ion gas flow rate on the coatings’ microstructure, hardness, and bonding performance were investigated. During the surfacing process, ${\mathrm{V}}_{\mathrm{x}}{\mathrm{C}}_{\mathrm{y}},{{\mathrm{M}}_7\mathrm{C}}_3\left(\mathrm{M}=\mathrm{F}\mathrm{e},\mathrm{C}\mathrm{r}\right)$ and other hard phases are in-situ generated throughout the entire PTA powder surfacing. These phases are uniformly distributed in the Fe matrix through precipitation and dispersion strengthening, yielding a surface hardness of up to 64.1 HRC. Also, the bonding performance between the substrate and coatings was evaluated by measuring the tensile strength, revealing that strong metallurgical bonds are formed, reaching a strength greater than 811 MPa.