A ternary compound additive for vacuum densification of β-silicon carbide at low temperature

The thermal decomposition behavior of a ternary carbide compound (Al4SiC4) was investigated under vacuum conditions. Decomposition of Al4SiC4 occurred above 1450 °C, resulting in the formation of SiC and carbon phases in the matrix, with some losses of Al. To simultaneously obtain the densification and refinement of SiC, the potential of the compound as a sintering additive for low-temperature sintering of SiC was evaluated and compared to cases of SiC with Al4C3 and Al2O3 additives. SiC that was almost entirely densified with fine and elongated grains was successfully formed using a 10 wt% Al4SiC4 additive by hot pressing at 1700 °C for 2 h in a vacuum. During the densification, the decomposition behavior of the Al4SiC4 was strongly related to the densification behavior of the SiC.