PREPARATION AND PROPERTIES OF BOROSILICATE-COATED ALUMINA PARTICLES FROM ALKOXIDES

This paper describes the synthesis of borosilicate-coated alumina part icles. Coated particles are agglomerate-free and contain up to 50 vol% coating. The ability to form uniform coatings is highly dependent upo n both the solution chemistry and the control of the nucleation and gr owth of the borosilicate on the alumina. The coated particles shown ma rkedly improved densification compared to that of a mechanical mixture of borosilicate and alumina. These composite powders (borosilicate-co ated alumina particles) are moisture-sensitive, resulting in a leached , phase-separated, boric oxide. The particles can be stabilized by fur ther encasing the particle with a thin layer of silica.