Results of a kinetic study of solid-phase interactions in stoichiometric oxide mixtures of mullite composition are reported. The mechanism of mullitization, irrespective of the oxide form (crystalline or amorphous), is diffusive in character. Topaz added in small quantities accelerates the process through generating surface and structure imperfections and activating the diffusion of reactants owing to the assistance of gaseous fluorides released by topaz. The secondary mullite produced by thermal degradation of topaz facilitates the formation of nucleation centers for topochemical reactions and activates the mullite crystallization.
ASJC Scopus subject areas
- Ceramics and Composites