铝热还原法合成TiN/刚玉复合陶瓷的研究

Study on TiN/Al_2O_3 Composite Ceramics Synthesized by Aluminothermic Reduction Process

以金属铝粉和钛白粉为原料,在流动氮气和匣钵埋碳保护气氛下采用铝热还原氮化法制备了TiN/刚玉复合陶瓷。采用XRD,SEM和TEM等分析手段,研究了铝热还原氮化法制备TiN/刚玉复合陶瓷在不同气氛和温度下的物相组成、晶格常数、显微结构。研究结果表明:在流动氮气和埋碳气氛下铝热还原法均可以制备TiN/刚玉复合陶瓷;处理温度和气氛明显影响着铝热反应的程度及产物的形貌,在埋碳条件下处理后的产物中TiN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。热力学计算发现埋碳条件下铝除参与铝热还原反应外,还与碳粉床中氧发生反应,导致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。

Using metal Al and TiO2 powders as starting materials TiN/ Al2O3 composite ceramics were prepared by aluminothermic reduction of TiO2 in coke bed and a flowing nitrogen stream. The phase composition, lattice parameter and the microstructure of products after treatment at different temperatures and under different conditions were analyzed by XRD, SEM and TEM. The results show that TiN/ Al2O3 composite ceramics can be produced in coke bed via aluminothermic reduction reaction or in flowing nitrogen. However, the treating temperature and atmosphere affects the evolution of aluminothermic reaction and morphology of products obviously. The TiN content, grain size and lattice parameter of TiN in products in coke bed were much lower than those in nitrogen stream. Thermodynamically it is confirmed that metal Al reacts with oxygen in coke bed while it is involved in aluminothermic reduction reaction, which caused the lack of Al taking part in the aluminothermic reaction and led to a surplus rutile in the products.