Oxidation behavior of β-SiAlON powders fabricated by combustion synthesis

The present study presents the effect of addition of diluents on the crystal morphologies and the impact on the oxidation resistance of β-SiAlON powders obtained from combustion synthesis method. Pure β-SiAlON were synthesized with diluents. It was observed by SEM that the diluents resulted in the transformation from large hexagonal column-shaped crystals to fine isotropic grains. Oxidation experiments were conducted by thermogravimetric analysis (TGA) in the temperature range from 1200 °C to 1400 °C. The TGA results indicated that oxidation was controlled by mixed chemical reaction and diffusion process. The chemical reaction step was found to be rate-controlling at low oxidation temperatures (1200 °C and 1300 °C), while at high temperature (1400 °C), diffusion was found to control the reaction rate. Oxidation products were investigated by X-ray Diffraction (XRD) analysis and found to be made up of SiO2, Al2O3. This research aims to provide guidance for the fabrication of β-SiAlON by combustion synthesis, thus facilitating its further application in high temperature industry.