Preparation of Uniform α-Alumina Microspheres by Catalytic Precipitation and Calcination Process

Abstract

Uniform α-alumina microspheres with mean partice size about 5-6 μm were prepared by the catalytic precipitation and calcination process. The spherical hydrated alumina precursor was first synthesized by the precipitation using ammonium aluminum sulfate and urea. During the reaction process, the urea can be decomposed to the mediator urease, which acts as the catalyst to influence the precipitate formation. The as-prepared α-alumina microspheres exhibit a very good shaping ability and the green body shaped by the dry-press process has a low linear shrinkage rate 5.8% at the sintering process.