Synthesis and oxidation behavior of Ti-Zr-Ta(Hf) high entropy carbide nanopowders by sol-gel method

Multi-component solid solution carbide is a promising material due to its excellent mechanical strength, thermal stability, and resistance to chemical corrosion. In this study, we intentionally designed and synthesized three types of solid solution carbide powders using the sol-gel method: (Ti _1/3Zr _1/3Ta _1/3)C, (Ti _1/3Zr _1/3Hf _1/3)C and (Ti _1/4Zr _1/4Ta _1/4Hf _1/4)C. The results show that the liquid-phase precursor undergoes pyrolysis at 800 °C and subsequently form homogeneous single face-centered cubic structure solid solutions upon thermal treatment at temperatures exceeding 1800 °C. The obtained powders exhibited ultra-fine and uniform particle sizes of 340 nm, 248 nm, and 401 nm, respectively. Furthermore, the oxidation behavior of the three types of carbide powders in air shows that Hf and Ta elements are of great significance in improving oxidation resistance. The solid solution of Hf increases the initial oxidation temperature, while Ta tends to form a complex oxide with Zr, which helps to improve the oxidation temperature resistance. This work therefore contributes to filling the gap of employing the sol-gel method in the fabrication of multi-component solid solution carbide materials and provides novel insights into their synthesis mechanism and oxidation behaviors.