Fabrication of a-AlO(OH) SiO2 with core-shell structures by heterogeneous nucleation-and-growth processing

Multicomponents mixture in the procedure of ceramic preparation is an important procedure, but it is difficult as multicomponents are mixed homogeneously in the traditional process. In order to solve this difficult problem, a novel processing (heterogeneous nucleation-and-growth processing) was used to prepare homogeneous distribution powders. Composite coating particles with mullite stoichiometric ratio (consisting of alpha monohydrate bauxite (a-AlO(OH)) cores without aggregation (average particle size 1.23 mm) with an outer homogeneous amorphous silica layer) were prepared by heterogeneous nucleation-and-growth processing. Effects of silica content in composite coating particles versus concentration of tetraethylorthosilicate, pH value, reaction time and reaction temperature were studied. A homogeneous amorphous silica layer on a-AlO(OH) cores was confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and zeta-potentials.