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

摘要

The thermal decomposition behavior of a ternary carbide compound (Al_4SiC_4) was investigated under vacuum conditions. Decomposition of Al_4SiC_4 occurred above 1450 deg 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 Al_4C_3 and Al_2O_3 additives. SiC that was almost entirely densified with fine and elongated grains was successfully formed using a 10 wt percent Al_4SiC_4 additive by hot pressing at 1700 deg C for 2 h in a vacuum. During the densification, the decomposition behavior of the Al_4SiC_4 was strongly related to the densification behavior of the SiC.