Powder mixtures of β-SiC-α-Si3N4 in a weight ratio of 1:1 containing 5-20 wt% Y-Mg-Si-Al-O-N oxynitride as a sintering additive were liquid-phase sintered at 1800 °C for 3 h by hot-pressing. These materials had a microstructure of `in situ-toughened composites' as a result of the α→β phase transformation of Si3N4 during sintering. The introduction of larger amount of additives accelerated the grain growth of elongated β-Si3N4 grains with higher aspect ratio, resulting in the improved fracture toughness and strength. Typical flexural strength and fracture toughness of SiC-Si3N4 composites containing 15 wt% oxynitride glass were 860 MPa and 5.7 MPa·m1/2, respectively.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering