Preparation of Mullite Powders by Sol-Gel Methods

Superfine Al2O3-SiO2 gel of mullite composition was prepared by a sol-gel method, using TEOS and aluminium chloride hexahydrates as starting materials. Its mullitization process was monitored by DTA, XRD and IR measurements. The as-received gel is a diphasic one, comprising of bayerite and amorphous silica. By going through transition phases of γ-Al2O3 and Al-Si spinel, this gel transforms to mullite at 1250℃. The mullite powder obtained has a very fine grain size and shows a plate-like morphology.