Low Temperature Pressureless Sintering of SiC Using an Aluminum Borocarbide Additive

The densification of an Al 3 BC 3 –SiC system during pressureless sintering was investigated. Densification of SiC could be achieved after sintering at 1850°C for 2 h by adding 10 wt% Al 3 BC 3 . The formation of partly crystallized grain boundaries and a core–rim structure within SiC grains indicated that liquid phase sintering was the major densification mechanism. The initial shrinkage at 1430°C was caused by the formation of a liquid silicate phase. Sintering shrinkage accelerated above 1580°C due to the rearrangement of SiC particles. The dissolution–reprecipitation of SiC and the final removal of pores occurred above 1780°C. In contrast to Al 2 O 3 additive which has low efficiency, Al 3 BC 3 strongly promoted the pressureless sintering of SiC .