Porous alumina ceramics produced by physical vapor deposition assisted freeze-casting method

Abstract

A novel physical vapor deposition assisted freeze-casting method was used to fabricate porous alumina. Through reserving a gap between the cold finger and the ceramic particle suspension, the lamellar ice crystals were firstly formed on the surface of the cold finger and grew toward the suspension by physical vapor deposition. Using a moderate gap width (2.5mm), the previously deposited lamellar ice could continuously grow into the suspension, forming lamellar alumina structure. A small (or large) gap would lead to a lamellar structure with a dense (or cellular) top layer. Simultaneously, the effects of gap size on the open porosity and compressive strength of the porous ceramics were discussed.