The sintered structures of amorphous Si 3N 4-BN composite powder were investigated with sintering aids from the Y 2O 3-Al 2O 3 and Y 2O 3-TiO 2-AlN systems. In the Y 2O 3-Al 2O 3 system, β-Si 3N 4 and h-BN crystallized during sintering. TiN additionally appeared in the Y 2O 3-TiO 2-AlN system. The microstructure of the Si 3N 4-BN composite was observed by SEM. Flaky BN particles with a length of about 1.0-1.5 μm were observed in the Si 3N 4 matrix. The Si 3N 4 matrix had a fine-grained microstructure in the Y 2O 3-Al 2O 3 system, whereas rod-like Si 3N 4 grains with a length of 3-10 μm were observed in the Y 2O 3-TiO 2-AlN system. The morphology of the TiN particles was observed by TEM. Small TiN particles of about 0.1 μm in diameter were included in large Si 3N 4 grains, but these fine TiN inclusions were a rare case. Large TiN particles of about 1 μm in diameter were located at grain boundaries throughout the sintered body. The thermal shock resistance of Si 3N 4 was improved by the BN inclusions in the Y 2O 3-Al 2O 3 system. With the Y 2O 3-TiO 2-AlN system, the TiN inclusions increased the fracture toughness of the Si 3N 4-BN composite but the thermal shock resistance was reduced.
|Number of pages
|Journal of Ceramic Processing Research
|Published - 2003
All Science Journal Classification (ASJC) codes
- Ceramics and Composites