Effects of different Si₃N₄ starting powders and sintering conditions on the grain morphology and mechanical properties of α-SiAlON ceramics

The preparation of α-SiAlON microstructures by β-Si₃N₄ starting powder or by applying nucleation step during sintering was studied. The application of sintering cycles on nucleation effect and the effect of different Si₃N₄ starting powders on the grain morphology of α-SiAlON ceramics and mechanical properties were investigated. Nucleation occured during the dwell time above eutectic temperature. The elongation in the grain was due to the pre-sintering cycles prior the final sintering at 1800°celcius. The results showed that the toughness was improved by the elongated grain morphology.