Study of the alumina sintering process with a low zirconia content

Abstract

One of the strategies for improving alumina ceramics' strength and optical properties is to eliminate grain growth during sintering. In this work, a casting process from water suspension was applied to prepare bulk alumina specimens doped with zirconia inclusions in the amount up to 0.5 wt.%. The effect of pure monoclinic (m-ZrO 2 ) or cubic zirconia (ZrO 2 stabilised with 8 mol.% Y 2 O 3 ) on the sintering and alumina grain growth up to 1600 °C was studied. The results demonstrate that even a negligible addition of zirconia particles (0.2 wt.%) reduces grain growth after sintering up to 1400 °C. At the sintering temperature of 1600 °C, significant grain growth was observed for both pure and doped alumina ceramics. However, the careful analysis of the grain size distribution revealed narrower distribution for zirconia-doped alumina compared to pure alumina ceramic. The Vickers hardness decreases with the increasing sintering temperature due to grains' growth independently on the load applied. The indentation fracture toughness of samples sintered at 1400 °C does not significantly depend on the presence of inclusions added in amounts up to 0.5 wt.%.