Densification of nanostructured alumina assisted by rapid nucleation of α-alumina

We have shown that it is possible to achieve dense nanostructured alumina, with density +98% of the theoretical maximum at sintering temperature as low as 1300 degrees C without any help of additives or alpha-seeding. The drastic reduction in sintering temperature from 1600 degrees C to 1300 degrees C is possible by rapid nucleation of the stable alpha-alumina phase. It is achieved by introducing the compacted pellet of bayrite fine particles derived by the sol-gel process, in a furnace at 1250 degrees C, the temperature high enough for the rapid transformation to alpha-alumina. Since the nucleation rate is higher than the growth rate of particles, large and extensive pore network which usually develops during the sequential transformation to alpha-Al2O3 could be avoided. This newly developed cost effective simple process of sintering through rapid nucleation win help to fulfill the demand of highly sintered nanostructured alumina for various industrial applications. (C) 1998 Elsevier Science B.V. All rights reserved.