Enhanced ablation resistance of pressureless liquid-phase sintered SiC ceramics via (Hf0.2Zr0.2Ta0.2Nb0.2Ti)B2 addition

Improving the ablation resistance of pressureless liquid phase sintered silicon carbide (PLS-SiC) is of great significance for its application in aerospace. In this paper, the ablation resistance of PLS-SiC ceramics was significantly improved by introducing high-entropy diboride (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Ti 0.2 )B 2 (HEB) as the second phase. The results showed that the matrix of the PLS-SiC ceramic with HEB addition kept its original dense structure after ablation in the presence of oxygen at high temperature (1300 °C/60min), while the matrix of the ceramic with HEB-free was full of pores after ablation, which indicated that it had failed. The improvement of ablation resistance was due to the formation of liquid phase by the reaction of SiO 2 with the oxidation products of HEB under high temperature and oxygen conditions, which filled the pores generated by the decomposition and migration of CeAlO 3 , inhibited the decomposition and migration of CeAlO 3 in the matrix, and maintained the integrity and performance of the material.