Densification of Nanostructured Alumina Assisted by Rapid Nucleation of (Alpha)-Alumina
V R. Palkar, D Thapa, M S. Multani, S G. Malghan
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 C without any help of additives of Α-seeding. The drastic reduction in sintering temperature from 1600 C to 1300 C is possible by rapid nucleation of the stable Α-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 C, the temperature high enough for the rapid transformation to Α-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 Α-Al2O3 could be avoided. This newly developed cost effective simple process of sintering through rapid nucleation will help to fulfill the demand of highly sintered nanostructured alumina for various industrial applications.