A diffusion-controlled mullite formation reaction model being based on tracer diffusivity data of aluminium, silicon and oxygen

Peter Fielitz (1) , Günter Borchardt (1) , Martin Schmücker (2) , Hartmut Schneider (2)

1 TU Clausthal - Clausthal University of Technology
2 DLR Institut für Werkstoff-Forschung / Institute of Materials Research

This paper compiles all data of our tracer diffusivity studies in single crystalline 2/1-mullite. As tracers we used the rare stable isotopes ¹⁸O and ³⁰Si and the artificial pseudo-stable isotope ²⁶Al. Secondary Ion Mass Spectrometry was applied to analyse the depth distribution of the tracer isotopes after the diffusion annealing. An essential result of our tracer diffusivity studies was the very low diffusivity of ³⁰Si compared to the diffusivities of ²⁶Al and ¹⁸O, which are almost equal. Based on this observation we propose a reaction model for the diffusion-controlled mullite formation in the solid state, which assumes that the growth kinetics of a mullite layer is mainly controlled by the diffusion of aluminium ions and oxygen ions.

Mots clés: Physical Sciences

Peter Fielitz, Günter Borchardt, Martin Schmücker, Hartmut Schneider. A diffusion-controlled mullite formation reaction model being based on tracer diffusivity data of aluminium, silicon and oxygen. Philosophical Magazine, 2006, 87 (01), pp.111-127. ⟨10.1080/14786430600917231⟩. ⟨hal-00513748⟩