A new measurement and treatment for kinetics of isothermal oxidation of Si3N4

The kinetics of the oxidation of α-Si3N4 powder has been investigated in the temperature range from 1373 to 1573 K experimentally in the air by using thermogravimetry. The results show that the major oxidation product was crystalline SiO2 and the oxidation reaction was mainly diffusion-controlled. Based on the experiment data, the new model for predicting the isothermal oxidation process of α-Si3N4 powder has been used, which offers an analytic form expressing the oxidation weight gain as a function of time and temperature explicitly. The comparison between experimental data and theoretical calculation shows that this new model works very well. Based on our model the activation energy for the oxidation of α-Si3N4 has been calculated to be 325.6 kJ/mol.