Kinetic study on the direct nitridation of silicon powders diluted with α-Si3N4 at normal pressure
来源期刊：International Journal of Minerals Metallurgy and Materials2013年第5期
论文作者：Shao-wu Yin Li Wang Li-ge Tong Fu-ming Yang Yan-hui Li
文章页码：493 - 498
摘 要：Silicon nitride （Si3N4） powders were prepared by the direct nitridation of silicon powders diluted with α-Si3N4 at normal pressure. Silicon powders of 2.2 μm in average diameter were used as the raw materials. The nitriding temperature was from 1623 to 1823 K, and the reaction time ranged from 0 to 20 min. The phase compositions and morphologies of the products were analyzed by X-ray diffraction and scanning electron microscopy, respectively. The effects of nitriding temperature and reaction time on the conversion rate of silicon were determined. Based on the shrinking core model as well as the relationship between the conversion rate of silicon and the reaction time at different temperatures, a simple model was derived to describe the reaction between silicon and nitrogen. The model revealed an asymptotic exponential trend of the silicon conversion rate with time. Three kinetic parameters of silicon nitridation at atmospheric pressure were calculated, including the pre-exponential factor （2.27cm·s-1） in the Arrhenius equation, activation energy （114kJ·mol-1）, and effective diffusion coefficient （6.2×108cm2·s-1）. A formula was also derived to calculate the reaction rate constant.
Shao-wu Yin1,2，Li Wang1,2，Li-ge Tong1,2，Fu-ming Yang1，Yan-hui Li1
1. School of Mechanical Engineering,University of Science and Technology Beijing2. Beijing Key Laboratory of Energy Saving and Emission Reduction for Metallurgical Industry,University of Science and Technology Beijing
摘 要：Silicon nitride （Si3N4） powders were prepared by the direct nitridation of silicon powders diluted with α-Si3N4 at normal pressure. Silicon powders of 2.2 μm in average diameter were used as the raw materials. The nitriding temperature was from 1623 to 1823 K, and the reaction time ranged from 0 to 20 min. The phase compositions and morphologies of the products were analyzed by X-ray diffraction and scanning electron microscopy, respectively. The effects of nitriding temperature and reaction time on the conversion rate of silicon were determined. Based on the shrinking core model as well as the relationship between the conversion rate of silicon and the reaction time at different temperatures, a simple model was derived to describe the reaction between silicon and nitrogen. The model revealed an asymptotic exponential trend of the silicon conversion rate with time. Three kinetic parameters of silicon nitridation at atmospheric pressure were calculated, including the pre-exponential factor （2.27cm·s-1） in the Arrhenius equation, activation energy （114kJ·mol-1）, and effective diffusion coefficient （6.2×108cm2·s-1）. A formula was also derived to calculate the reaction rate constant.
关键词：
