天然红柱石莫来石化后热喷涂粉末的制备

摘要

To obtain mullite thermal spray powders,natural andalusite powders were annealed at 1480℃in air for 4 h to promote their mullitization,then,after adding an appropriate amount Al 2 O3 powders,the secondary mullitization was carried out.The mullitized powders were prepared by spray-dried process.The component and phase structure of the powders before and after mullitzation were analyzed,the size distribution of the powders was tested,and the morphology of spray-dried powders was investigated.The results showed that the primary mullitized andalusite powders contained mullite and about 20wt%SiO2.After the secondary mullitization,the powders were constituted of mullite and a limited amount of Al 2 O3.The fluidity and apparent density of spray-dried powders were improved by heat-treatment,and its typical size distribution was suitable for air plasma spray.%为获得莫来石热喷涂粉末,采用天然红柱石粉末作为原料,在1480℃保温4 h完成一次莫来石化后,加入适量Al2O3再次在1480℃保温4 h进行二次莫来石化反应,利用喷雾干燥工艺制备莫来石粉末,分析了红柱石粉末和莫来石化粉末的成分及相组成,测试了粉末粒度分布,表征了粉末的形貌.结果表明：天然矿物红柱石粉末一次莫来石化后,粉末主要由莫来石和质量分数约20%的SiO2组成;经过二次莫来石化反应后,粉末成分为莫来石和微量的Al2O3;二次莫来石化的粉末经喷雾干燥、热处理后,粉末的流动性和松装密度得以改善;热处理后粉末粒度呈典型的正态分布,且粒径尺寸适合大气等离子喷涂.