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High Temperature Material Processes (An International Quarterly of High-Technology Plasma Processes)

Impact factor: 0.189

ISSN Print: 1093-3611
ISSN Online: 1940-4360

High Temperature Material Processes (An International Quarterly of High-Technology Plasma Processes)


16 pages

DIFFUSIONAL MODEL APPLIED TO SOLID-SOLID REACTIONS

Alexandra Maitre
Laboratoire Science des Procedes Ceramiques et Traitements de Surface UMR CNRS 6638 123 Avenue Albert-Thomas F-87060 Limoges Cedex, France
Pierre Lefort
Laboratoire Science des Precedes Ceramiques et Traitements de Surface UMR CNRS 6638 123 Avenue Albert-Thomas F-87060 Limoges Cedex, France

ABSTRACT

On the basis of a sintering model, the diffusion rates of a reactive system (Ti3O5/C giving Ti2OC) were evaluated. Three elementary steps were considered: volumic diffusion through the neck supposed to be formed between two grains (C and Ti3O5) during their reaction ; surface diffusion on the external surface of the neck; gaseous diffusion of reactive gas (CO or CO2). Theoretical diffusion rates were obtained/or a real powder bed with the estimate of the number of contacts between the grains following Cournil-Thomas's model. The comparison with the experimental rate of the reaction at 1523 К shows that the theoretical diffusion rates were 103 to 108 times higher. This confirms previous results which show that diffusion cannot be the limiting step of this system, in respect of the classical Langmuir-Hinshelwood's model. Such a kind of calculation could be extended to many other reactive systems.