Influence of TiC addition on ablation and thermal shock behaviour of microwave sintered ZrB2–SiC–TiC composites

Abstract

Ultra-high temperature ceramics should possess excellent ablation and thermal shock resistance in order to endure severe temperatures for ultra-high temperature space applications. The study reports the effect of TiC (5–10 vol. %) addition on ablation and thermal shock resistance of microwave sintered ZrB2-25 SiC (vol. %) composites. The ablation and thermal shock resistance improved with TiC addition due to the formation of TiO2 and ZrO2.TiO2 layers on the surface of oxidized composites. The composites retained up to 91.95% of maximum hardness and 91.61% of maximum fracture toughness after ablation. Crack deflection and crack bridging were observed as the primary toughening mechanisms after ablation. The thermal shock resistance also improved with TiC addition. The analytically estimated thermal shock parameters as well as the experimentally measured critical temperature difference increased with TiC addition. The enhancement in thermal shock resistance was ascribed to the higher flexural strength and fracture toughness of developed composites.