PRESSURELESS SINTERING OF SOL-GEL DERIVED ALUMINA-ZIRCONIA COMPOSITES

Alumina-zirconia (pure zirconia, 12 mol % ceria stabilized zirconia an d 3 mol% yttria stabilized zirconia) composites containing 5, 10, 15, 20 and 25 vol.% zirconia were prepared by sol-gel technique. The proce dure involved the following steps: preparation of stable (hydrous) alu mina and zirconia sole, mixing of sols in proper ratio, to obtain the final precursor with the desired composition and finally stabilizing t he mixed sols. Thermal analysis was carried out for the dried precurso r. The sol-gel derived precursors were calcined at different temperatu res and their crystallization behavior was studied using X-ray diffrac tion (XRD) technique. Samples calcined at 950 degrees C sintered well than those calcined at other temperatures. All the samples were sinter ed at 1530 degrees C for 3 h by pressureless sintering, which yield up to 99.8% of the theoretical density of the composite. (C) 1998 Elsevie r Science S.A. All rights reserved.