Effect of AlN additive on densification, microstructure and strength of liquid-phase sintered SiC ceramics by spark plasma sintering

SiC ceramics were prepared from β-SiC starting powder with AlN and Y2O3 sintering additives by spark plasma sintering. Densification, microstructure and flexural strength of the liquid-phase sintered SiC ceramics were investigated. The relative density of SiC sintered bodies reached over 95% at total amount of 10 vol% AlN and Y2O3 additives and at 1900°C for 600 s in N2 at 30 MPa. When the content of AlN additive increased, the size of SiC grains decreased. The SiC body almost without the grain growth was successfully prepared using 95 mol% AlN and 5 mol% Y2O3 additives. The flexural strength of the SiC body was 1150 MPa.