Effects of powder characteristics, solid loading and dispersant on bubble content in aqueous alumina slurries

Bubbles occurring in ceramic slurries usually result in formation of abnormal pores in the subsequently consolidated green samples, thus deteriorating the properties of the final ceramic product. In this work, bubble content and its stability in aqueous alumina slurries were investigated with applying vacuum deairing. The experimental results show that the powder characteristics and solid loading greatly affected the bubble stability in the slurries and thus determined the bubble content. The bubble content was obviously increased with increasing solid loading, as well as using powders of high specific surface area in both as-prepared and deaired slurries. The stabilization mechanism of air bubbles in the slurries is attributable to the enhanced hindrance effect on bubble uprising caused by dense particle arrangement in slurry bulk, and the increased strength of bubble films at the slurry surface. (c) 2006 Elsevier Ltd. All rights reserved.