Effect of Al4SiC4 additive on the densification of β-silicon carbide under vacuum

Abstract

Abstract The potential of ternary compound (Al 4 SiC 4 ) powders as an effective sintering additive to concurrently achieve SiC densification and grain refinement was evaluated under vacuum. Nearly fully densified SiC ceramic was successfully obtained in the absence of a residual liquid phase at the grain boundaries using low temperature hot pressing at 1700 °C by adding 10 wt% Al 4 SiC 4 as an additive. The main mechanism for obtaining SiC densification was analyzed with changing additive contents. A larger amount of additive content was effective in suppressing the grain growth of SiC due to the formation of newly generated carbon by the thermal decomposition of Al 4 SiC 4 . Regardless of the additive content, sintering temperature and grain size, the fracture mode of the Al 4 SiC 4 -doped SiC mainly consisted of intragranular fractures due to the high interfacial bonding strength.