Abstract
Porous alumina prefired bodies filled with 10- 40wt% of Al2O3 were fabricated via impregnation - dehydration - thermal decomposition (impregnation method) using a saturated Al(N03)3 solution. The possibility of utilizing the impregnation method as a means of near net shaping for ceramics was investigated by evaluating the sinterability of these ceramics. Al2O3 prefired bodies filled with 40wt% of Al2O3 were prepared by repeating the impregnation process at 400° to 800°C. The impregnated aluminum oxides were amorphous, η- and α -Al2O3 according as the thermal-decomposition temperature. Both the sinterability of an Al2O3 prefired body with high density and the dimensional stability of the fabricated Al2O3 sintered body were markedly improved with this process. It was observed that the fine structure of the Al2O3 sintered body derived from an Al2O3 prefired body with high density-filling of Al2O3 was made uniform by controlling the crystallization and transition to α-Al2O3 of thermally decomposed filled powders.
