碳热还原反应法合成氮化铝的研究

Study on Carbothermic Reduction of A1_20_3 Synthesized AIN

本实验采用碳热还原反应法合成氮化铝纤维,得到与氧化铝不同形貌的氮化铝。这与以前实验结果不同。本实验认为氮化铝碳热还原反应过程可以分为气—固两步进行,即当氧化铝与氮气和活性碳充分接触时,氧化铝在活性碳的作用下被还原成铝的低价氧化物并进一步氮化;而当氧化铝被第一步反应生成的氮化铝包裹严密不能与氮气和活性碳充分接触时,反应通过固相扩散来进一步完成,在固相扩散过程中,既包括了活性碳和氮气的扩散,也包括了铝离子的扩散,反应是在氮化铝层两个界面同时进行。

AIN were synthesized by carbothermic reduction of A1 20 3. The mechanism of carbothemal reduction and nitridation of A1 20 3 were studied. The reaction was believed to contain two steps. Firstly, when A1 20 3 was contacted with N 2, the reaction rate was controlled by the reduction and decomposition of A. Secondly,when the A1 20 3 was coated by AIN layer formed in the first step, the rate of the reaction was controlled by the diffusion of N2,C and Al iron.