Influence of Atmosphere on the Phase Transition of Alumina

Abstract

Aluminum compounds change to α-alumina finally via intermediate phases during firing. The intermediate phases have large specific surface areas and high ability of gas adsorption. This character suggests the phase transition is subjected to the influence of atmosphere. This phenomenon is important to the storage of alumina powders. A crystalline aluminum hydroxide (gibbsite), amorphous aluminum hydroxide and amorphous alumina were selected and their phase transition sequences were investigated in various common atmospheres, that is, water vapor, carbon dioxide and vacuum.