The Role of Water Vapor in Formation of Alpha Alumina from Transient Alumina

Abstract

Kinetics of alpha alumina formation from two types of transient alumina, gamma and theta, has been investigated considering the role of water vapor. The mechanism was of nucleation determinant. Water vapor facilitated nucleation of alpha alumina and lowered the activation energy for the process. Under the high vapor pressure of water, however, the fraction of alpha alumina was apparently saturated in the present work. Water vapor generated from the lattice of gamma alumina also behaved like a catalyzer for the nucleation process of alpha alumina. Crystallite size of transient alumina must be considered in order to clarify the nucleation process. The role of water vapor is essential in the rection of alpha alumina formation from transient alumina.