柱状自生长莫来石的制备及显微结构

FABRICATION AND MICROSTRUCTURE OF CYLINDRICAL PARTICLES GROWING IN SITU IN MULLITE CERAMICS

通过对莫来石材料的分析，设计了在莫来石先质中添加ＡｌＦ３，进行密闭条件下热处理，生成莫来石晶须晶种，并以其作为生长点，在以后的烧结过程中发育成为柱状晶粒，获得类晶须复合材料的显微结构的实验路线．含ＡｌＦ３莫来石先质试样密闭处理的温度条件是１１５０℃，大于这个温度处理的试样无法获得致密烧结．莫来石柱状生长条件是富铝莫来石晶粒的存在和液相的产生．本工作中经１１５０℃处理后的试样获得良好的烧结密度。

Microstructure of mullite ceramics was designed. AlF3 was added into mullite precursor and than heat-treated in air-tight condition. During this processing, mullite whisker nuclei grew and developed to cylindrical particles after sintering. Whisker reinforcement similar to ceramic microstructure could be obtained. The experimental results demonstrate that 1150℃ is a proper heat-treated temperature. Samples heat_treated above 1150℃ can not be fully sintered. The grains growth conditions of cylindrical mullite are: a) existence of grains with high Al2O3/SiO2 ratio; b) existence of liquid phase. In this experiment, after heated at higher temperature, mullite (fine grains)/mullite (cylindrical grains) multi-phase microstructure were obtained for the samples containing AlF3 heat-treated at 1150℃ in air-tight condition.