氧化镁-氧化铝粉末成型体生成镁铝尖晶石的膨胀机制  

Expansion mechanism of spinel formation from MgO-Al_2O_3 powder compacts

作　　者：陈伟鹏[1] 洪澜[1] 王东[1] 张文帝[1] 张丹丹[1] 叶霖海 王慧华[1] 

机构地区：[1]苏州大学沙钢钢铁学院,江苏苏州215006

出　　处：《耐火材料》2017年第4期272-276,282,共6页Refractories

基　　金：江苏省自然科学基金资助项目(BK20140346)

摘　　要：为了研究生成镁铝尖晶石的反应过程,以电熔镁砂粉和α-氧化铝微粉为原料制备粉末成型体合成镁铝尖晶石,通过考察在1 300~1 400℃空气中反应一定时间(1.5~25 h)后的永久体积膨胀率、线膨胀率、相组成及显微结构,研究了氧化镁和氧化铝反应生成镁铝尖晶石的膨胀机制。结果表明,反应体系的永久膨胀率随成型压力的增加而增大,这除了由反应前后各组成密度差引起之外,还与反应过程中可能存在的Kirkendall效应有关;永久线膨胀率随时间的变化规律遵循固相扩散理论,据此计算出活化能为304.0 k J·mol-1。In order to investigate the reaction process of magnesium aluminate spinel formation,fused magnesia and α-Al2O3 micropowders were used as the starting materials to prepare magnesium aluminate spinel through MgO-Al2O3 powder compacts. The permanent volume expansion rate, linear expansion rate, phase composition,and microstructure of the specimens fired at 1 300 - 1 400 ℃ in air for 1.5 -25 h were determined to investigate the expansion mechanism of the spinel formation. The results show that the permanent expansion increases with the shaping pressure increasing, which is caused by the density difference of the constituents before and after the reaction,and probably by the Kirkendall effect during the reaction process as well ;the change of linear expansion rate along time follows solid state diffusion mechanism, based on which the apparent activation energy of the reaction is calculated as 304.0 kJ ·mol^-1.

关 键 词：镁铝尖晶石 膨胀机制 永久膨胀率 固相扩散 粉末成型体 

分 类 号：TQ175.1[化学工程—硅酸盐工业]