A new approach to interpreting the parabolic and non-parabolic oxidation behaviour of hot-pressed beta-SiAlON ceramics

The oxidation behaviour of hot-pressed β-SiAlON ceramics with different densities has been investigated up to 1853. K in air using thermogravimetry (TG). The microstructures of the oxidised samples were determined by scanning electron microscopy (SEM), and the phases after oxidation were confirmed by X-ray diffraction (XRD). The oxidation kinetics of the higher density sample was diffusion controlled. For the lower density sample, it was controlled by both an interface reaction and diffusion in the early stage but diffusion controlled after a certain time. The oxidation curves can be well described by Chou's model with the "characteristic oxidation time" index introduced