Fabrication of Mg and Ti-doped submicron-grained alpha-alumina-based ceramics

Nanocrystalline alumina ceramics were prepared by magnetic-pulse compaction followed by pressureless sintering. The relative density of green compacts exceeded 0.7. The medium in which the starting powders were classified (ga s, water, or ethanol) was shown to have a significant effect on their sinte rability. The effects of Mg and Ti additions on the sintering behavior of A l2O3 were studied under optimized heat-treatment conditions. Mg-doped alpha -Al2O3 ceramics containing uniformly distributed MgAl2O4 (similar or equal to4 wt%) and offering hardness values of up to 24 GPa were prepared. In th e course of sintering, the grain size of these ceramics increases from 110 to 300 nm, and their relative density rises from 0.94 to 0.98.