High-temperature oxidation of sintered silicon carbide under pure CO2 at low pressure:: active-passive transition

The study of the oxidation of SiC under CO2 at high temperature and low pressure is achieved by means of theoretical and experimental determinations of the transition zone between the passive oxidation with formation of a protective silica layer and the active oxidation with major vaporization of SiO and etching of the SIC material. The theoretical determination is done using both models: a computer model "Solgasmix", applied for a closed system at equilibrium and the other, our analytical model, which takes into account the mass transfer at the solid/gas interface. The comparison is done for these two models and then with the experimental results. XPS analyses are performed on "passive" and "active'' samples to confirm the position of the transition line. Moreover, SEM micrographs complete the diagnostics. (C) 1998 Elsevier Science B.V. All rights reserved.