反应气氛对铝热还原氧化钛合成氮化钛的影响

研究在流动氮气和埋炭条件下铝热还原氮化TiO2的反应过程,借助于X射线衍射(XRD)和扫描电子显微镜(SEM)分别测试和观察两种气氛中不同温度下处理后产物的物相组成和显微结构。结果显示,与流动氮气氛下一样,在埋炭气氛下采用铝热还原氮化法可以制备氮化钛复相材料,但处理气氛明显影响着铝热反应的程度及产物的形貌,在埋炭条件下处理后的产物中氮化钛含量、晶粒大小、晶格常数明显低于流动氮气氛下处理产物中上述各项值;热力学计算发现埋炭条件下铝除参与铝热还原反应外,还与炭粉床中氧发生反应,使参与铝热反应的金属铝不足,造成产物中有剩余的金红石存在。

Effect of atmosphere on synthesis of titanium nitride in aluminothermic reduction process

The synthesis of titanium nitride(TiN) by aluminothermic reduction of TiO2 in coke bed and in flowing nitrogen stream was investigated.The phase composition and microstructure of the products after treatment in different conditions were analyzed by XRD and SEM.The results show that TiN containing composite powders can be produced in coke bed via aluminothermic reduction reaction similar to that in flowing nitrogen.However,the atmosphere affects the evolution of aluminothermic reaction and the morphology of the products significantly.The content,grain size and lattice parameter of TiN in the products in the coke bed were lower than those in nitrogen stream.It is confirmed that metal Al reacts with oxygen in coke bed during the aluminothermic reduction reaction resulting in the lack of Al required for the aluminothermic reaction and leading to a surplus rutile in the products.