Fabrication of low cost fine-grained alumina powders by seeding for high performance sintered bodies

The effect of seeding into commercial aluminum hydroxide on the a-alumina transition temperature, powder characteristics and properties of sintered bodies was investigated, with the purpose of obtaining high performance sintered bodies from low cost raw material. A small amount of fine a-alumina seed addition, which was worn from wet ball milling, drastically lowered the a-alumina transition temperature. The particle size of the low temperature transformed seeded powder was smaller than non-seeded powder. This powder could be sintered to full dense at lower temperature. The abnormal grain growth, which is often observed in high temperature sintered usual purity alumina, occurred at lower temperature in the sintered low temperature transformed seeded powder. However, the abnormal grain size was small and the number of the grains was high. The sintered bodies with these microstructures show high bending strength and very high fracture toughness. (C) 2003 Elsevier Ltd. All rights reserved.