Thermodynamic considerations on the in-situ formed interface structure observed in Si-Ti-C-O-fiber/SiO2-glass composite

Si-Ti-C-O-fiber/SiO2-glass composite was prepared by oxidation of the fiber s at ambient temperature and subsequent hot-pressing at 1750 degrees C (50- 70 MPa). The matrix was built by a silica layer on the fiber surfaces forme d during initial oxidation. High-resolution transmission electron microscop y (HRTEM) revealed the in-situ formation of a graphitic interface with both turbostratic and cellular configuration in addition to TiC crystallites, a lso precipitated within the silica matrix. Thermodynamic considerations ind icate the possibility of active oxidation of SiC in the Tyranno fiber yield ing gaseous silicon monoxide and solid carbon.