Transformation Kinetics of Diphasic Aluminosilicate Gels
Journal
Journal of the American Ceramic Society
Journal Volume
71
Journal Issue
7
Pages
581-587
Date Issued
1988
Author(s)
Abstract
The formation of mullite in diphasic aluminosilicate gels of stoichiometric composition was studied by quantitative X‐ray diffraction (QXRD) and electron microscopy (AEM and SEM). The transformation is preceded by an incubation time which is apparently an activated process with an activation energy of 236 ± 15 kcal/(g·mol) (∼987 ± 63 kJ/(g·mol)). Microscopic observations show that mullitization occurs via nucleation and growth as a mechanism either interface‐controlled or controlled by short‐range diffusion near the interface. The kinetic time exponent (n), determined by microstructural and QXRD observations, is close to 1.3. The transformation kinetics involve a nearly constant nucleus density, and time‐dependent growth rate for nearly spherical grains. A linear time‐temperature‐transformation diagram is observed. Copyright © 1988, Wiley Blackwell. All rights reserved
Type
journal article