Effect of Seed Crystal Properties on the Microstructure of Si<sub>3</sub>N<sub>4</sub> Ceramics

Abstract

The effect of seed crystal properties on the microstructure of Si3N4 ceramics was investigated. Three β-Si3N4 powders with average grain size of 0.74, 5.84 and 21.66μm and β-Si3N4 whiskers were used as seeds. Seeds (2mass%) were added to the mixture of α-Si3N4 and sintering aids, and the mixture was hot-pressed at 1850°C for 8h. Growth of large rodlike-grains was enhanced by the micron-sized single-crystalline β-Si3N4 particle. Crushed β-Si3N4 whiskers were similarly effective in growing rodlike-grains. On the contrary, polycrystalline β-Si3N4 particles and submicron-sized β-Si3N4 particls did not affect greatly the final microstructure.