A novel processing route for whisker shaped mullite-alumina composites from kaolin

Whisker shaped mullite/particulate alumina composites prepared by a two-step in situ processing route have been characterized in terms of their microstructure and mechanical properties. Well-developed mullite whiskers were firstly formed at 1300 degrees C for 15 h and subsequently sintered at higher temperatures (<= 1650 degrees C). A liquid phase was formed by the reaction of SiO2 and Al2O3, aided by the presence of Na2O and P2O5; these additions improved the formation and growth of mullite whiskers. The mechanical properties of the sintered materials appeared to be mainly governed by the grain size of the major phase, the presence of voids, and an intergranular glass.