Microstructure and thermal physical properties of SiC matrix microencapsulated composites at temperature up to 1900 °C

Abstract

SiC matrix microencapsulated composites with particle-free buffer (PB) layer were produced by spark plasma sintering for the first time. Microstructure and thermal physical performance of the composites from room temperature to 1900 °C were investigated. Dense composites with rational layout of tristructural isotropic (TRISO) particles and PB layer were obtained. The TRISO particles in the composites kept intact spherical shell structure. Thermal physical properties of the composites approached those of the SiC materials. The composites with high thermal conductivity and low coefficient of thermal expansion were suitable for nuclear applications. The effect of oxide additives on comprehensive performance of the composites was reappraised. Dissolution and recrystallization of SiC in the eutectic liquid phase revealed a new high temperature failure mechanism for the composites.