In order to solve the difficult problem of heterogeneity of different components in the procedure of ceramic preparation, a novel processing (heterogeneous nucleation-and-growth processing) was used to prepare homogeneous distribution powders. Composite homogeneous coating particles with mullite stoichiometric ratio (consisting of alpha alumina cores (average particle size 0.26 mum) with an outer homogeneous amorphous silica layer) were prepared by the heterogeneous nucleation-and-growth processing. Effects of silica content in composite coating particles versus concentration of tetraethylorthosilicate (TEOS), pH value, reaction time and reaction temperature were studied. The homogeneous amorphous silica layer on cores was confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and zeta potential measurement. (C) 2002 Elsevier Science B.V. All rights reserved.