TIAN Xue ¹, LI Cuiwei ¹, WU Linghao ¹, BIAN Chao ¹, WANG Chang’an ²

(1. School of Mechanical and Electronic Control Engineering, Beijing Jiaotong University, Beijing 100044; 2. State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China)

Abstract: Mullite whisker is an excellent kind of reinforcments used in ceramic matrix composite, due to its’ good properties such as high temperature resistance, good oxidation resistance, small coefficient of thermal expansion, good strength in high temperature, good thermal shock resistance and so on. Mullite whisker was prepared through solid reaction using γ-Al₂O₃ and SiO₂ as raw material, aluminum fluoride as additives. Phase composition of the as-prepared material was analyzed by XRD and microstructure was observed by SEM. The result shows that when the raw powder materials with a certain content of fluoride are naturally packing, the factors who affects aspect ratio of mullite whisker are proved to be holding time, calcining temperature and the kind of the aluminum fluoride. Using 10wt.% AlF₃·3H₂O as additive, mullite whisker with high purity and aspect ratio of about 20 can be prepared after calcined at 1450 ℃ for 6 hours. There are differences in the dispersibility of the whisker due to its situation in the crucible. The ultrasonic vibration, polar solvent and alkaline environment are helpful to the dispersion of the prepared mullite whiskers.
Key words: mullite whisker; preparation; reunion; dispersion