Molten salt synthesis and spark plasma sintering of (TiNbTaV)C–SiC ceramics: Microstructure, mechanical performance, and high-temperature behavior

In this study, (TiNbTaV)C-SiC composite powders were synthesized via a molten salt method and subsequently consolidated using spark plasma sintering to fabricate (TiNbTaV)C-SiC ceramics. The synthesized composite powders exhibited fine particle sizes (D50–1.19 μm) and high phase purity, consisting predominantly of high-entropy carbide and silicon carbide. The effects of the synthesized powders and sintering temperature on the phase composition, microstructure, physical properties, and high-temperature stability of the ceramics were systematically investigated. Results indicate that silicon carbide is uniformly dispersed within the high-entropy carbide matrix. Compared to ceramics made with commercial SiC powders, those prepared using molten salt-synthesized powders exhibited significantly enhanced density, flexural strength, fracture toughness, and hardness. However, the high-temperature oxidation resistance was reduced. Furthermore, increasing the sintering temperature from 1700 °C to 1900 °C led to a grain size increase in the high-entropy carbide phase from 3.46 to 4.72 μm. Concurrently, the relative density, flexural strength, fracture toughness, and hardness improved from 97.8 % to 98.5 %, 310.6 MPa–429.0 MPa, 3.2 MPa m 1/2 to 4.5 MPa m 1/2 , and 19.8 GPa–22.2 GPa, respectively.