莫来石晶粒柱状生长对莫来石基陶瓷力学性能的影响

The Effects of Rod-Like Mullite Grain Growth on Mechanical Properties of Mullite Matrix Ceramics

将ＡｌＦ３加入莫来石（莫来石／氧化锆）先质中，生坯试样经密闭处理及常压烧结，可获得莫来石柱状晶粒生长。实验结果表明：莫来石柱状生长使莫来石陶瓷在其强度不下降的前提下，韧性提高，且随柱状晶粒粒径增大而增加有类似架桥作用。ＺＴＭ（含ＡｌＦ３）材料韧性的提高是由于莫来石柱状晶粒生长使ｔ－ＺｒＯ２形态发生了变化，具有较大长径比或有尖角的不规则形态的ｔ－ＺｒＯ２晶粒容易发生应力诱导相变。

AlF3 was added into mullite (mullite/ZrO2) precursor and then heat-treated in air tight conditionAfter sintered at high temperature,mullite/mullite(rod-like) and ZTM/mullite (rod-like) microstructures were obtainedThe growth of rod-like grains improved the fracture toughrness of mullite and the improvement increased as the diameter of rod-like grains increasedCrake bridging by rod-like grains was assumed to be the main toughening mechanism to mullite ceramicsIn ZTM,the t-ZrO2 grains with large aspect ratio or sharp angles caused by growth of rod-like mullite were easier to satisfy the critical stress condition of transformationThus the mechanical properties of ZTM material were improved obviously