Kinetics analysis of direct nitridation of silicon powders at atmospheric pressure

摘要

Silicon nitride powders were prepared via direct nitridation of silicon powders diluted with α-Si_3N_4 at atmospheric pressure. The nitridation temperature and time were ranged from 1623K to 1823K and from 0 minute to 20 minutes respectively. Based on the relations between the conversion rate of silicon and the time at different temperatures, and using shrinking core model, a simple model for the reaction between silicon and nitrogen was derived. The model showed that the relations between the conversion rate of silicon and the time displayed asymptotic exponential conversion trend. Using this model, the kinetics parameters of nitridation of silicon powder at atmospheric pressure were calculated, including pre-exponential factor in Arrhenius equation, activation energy, effective diffusion coefficient, and the formula of the reaction rate constant.