Room-temperature gelcasting of alumina with a water-soluble copolymer

A novel and simple method for gelcasting of alumina was developed using a nontoxic and water-soluble copolymer of isobutylene and maleic anhydride (commercially called Isobam). In this method, there is requirement of only a small amount of Isobam (0.3 wt%) and neither initiators nor dispersants are needed for preparation and gelation of a 50 vol% solids loaded alumina slurry. The gelation rate increased with increasing solids loading but decreased with increasing Isobam content. A typical gelation time was 38 min for the slurry containing 50 vol% solids loading and 0.3 wt% Isobam. The resultant wet gel was strong enough to allow reversible bending and twisting. This simple gelling system is attractive for wet forming of ceramics because only a single additive, which acts as both dispersant and gelling agent at room temperature in air, is used.