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

The potential of ternary compound (Al4SiC4) 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% Al4SiC4 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 Al4SiC4. Regardless of the additive content, sintering temperature and grain size, the fracture mode of the Al4SiC4-doped SiC mainly consisted of intragranular fractures due to the high interfacial bonding strength.