Effect of plate-like alumina on the properties of alumina ceramics prepared by gel-casting

In this work, alumina ceramics were prepared via gel-casting by mixing plate-like and granular alumina powders. Plate-like alumina with a hexagonal or disk-shaped morphology decreased the viscosity of the suspension remarkably, which made the casting process much easier. As the plate-like alumina content varied from 10 wa, 30 wt%, 50 wt%, 70 wt% to 100 wt%, the density and bending strength of the sintered ceramics increased firstly then decreased and reached their maximum at the content of 50 wt%. However, the microhardness and fracture toughness presented negligible dependence on plate-like alumina content. It is worth noting that all samples with plate-like alumina displayed lower density and bending strength but higher fracture toughness than the sample without plate-like alumina. (C) 2013 Elsevier B.V. All rights reserved.