Kinetic equation of oxidation process with diffusion controlled step in solid product layer is deduced, in which the influence of particle size distribution of β-SiAlON on the reaction rate has been taken into account. This equation was applied to the oxidation of β-SiAlON powder, and fitted well with the experimental data. Comparisons with the results offered by the model using one and two effective radiuses are also included, from which it can be seen that the model considering particle size distribution is the best for describing the kinetics of powder system. The activation energy ΔE of oxidation of β-SiAlON powder is also obtained, which is 258 kJ mol−1.
