Oxidation mechanisms and kinetics of 1D-SiC/C/SiC composite materials; 1: An experimental approach
- Domaine Univ., Pessac (France). Lab. des Composites Thermostructuraux
- Societe Europeenne de Propulsion, Saint Medard en Jalles (France)
The oxidation of unidirectional SiC/C/SiC model composites has been investigated through thermogravimetric analysis, optical/electron microscopy, and electrical measurements. The influence of temperature and carbon interphase thickness on the oxidation of the composites is discussed. The oxidation involves three phenomena: (1) reaction of oxygen with the carbon interphase resulting in pores around the fibers, (2) diffusion of oxygen and carbon oxides along the pores, and (3) reaction of oxygen with the pore walls leading to the growth of silica layers on both the fibers and matrix. In composites with a thin carbon interphase treated at T > 1,000 C the pores are rapidly sealed by silica. Under such conditions, the oxidation damages are limited to the vicinity of the external surface and the materials exhibit a self-healing character. Conversely, long exposures at 900 C give rise to the formation of microcracks in the matrix related to mechanical stresses arising from the in situ SiC/SiO[sub 2] conversion. Finally, the self-heating character is not observed in composites with a thick interphase since carbon is totally consumed before silica can seal the pores.
- OSTI ID:
- 7207439
- Journal Information:
- Journal of the American Ceramic Society; (United States), Journal Name: Journal of the American Ceramic Society; (United States) Vol. 77:2; ISSN 0002-7820; ISSN JACTAW
- Country of Publication:
- United States
- Language:
- English
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