Fabrication of ultrafine mullite powders

In order to obtain fine mullite powders by a simple and inexpensive processing route gamma alumina (γ-Al2O3) is used as raw material, and the heterogeneous nucleation-and-growth process is chosen. Composite coating particles consisting of γ-Al2O3 cores with outer homogeneous amorphous silica layer are prepared by the heterogeneous nucleation-and-growth process in the ethanol suspension containing ammonia, tetraethylorthosilicate (TEOS) and γ-Al2O3. Ultrafine mullite powders (average particle size of 0.63 μm) were fabricated by calcined composite coating particles at 1400 °C for 2 h.