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Kinetics and mechanism of corundum formation in the thermal decomposition of basic aluminium chloride gels
Author(s) -
Brand P.,
Ziegenbalg G.,
Köhnkem K.
Publication year - 1994
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.2170290205
Subject(s) - corundum , thermal decomposition , aluminium , decomposition , chemistry , kinetics , chloride , crystallization , aluminium chloride , diffusion , chemical engineering , inorganic chemistry , mineralogy , organic chemistry , thermodynamics , physics , quantum mechanics , engineering
Compositions and corundum contents in products, formed by thermal decomposition of a basic aluminium chloride gel at temperatures up to 600 °C, were determined at variable temperatures and times of decomposition. For the kinetics of α‐alumina crystallization a model is proposed, valid for diffusion‐controlled two‐dimensional growth. A mechanistic interpretation of these results and of those from previous examinations is based on the essential influence of the gel structure and of the atmosphere in thermal decomposition. As the rate‐controlling step of corundum formation the transportation of HCl and H 2 O molecules is discussed.