High temperature oxidation behaviors of C/C composites with SiOC coatings

The oxidation behaviors of C/C composites with various silicon oxycarbide (SiOC) coatings prepared at various deposition temperatures (1300 - 1513 K) were studied. The SiOC coating improved the oxidation resistance of C/C composites by forming dense SiO2 glass, but such an improvement was sensitive to the deposition temperature. The SiOC coatings prepared at low temperatures exhibited limited oxidation resistance improvement given the appearance of penetrating cracks, fundamentally caused by their thin, amorphous (high elastic modulus), dense, and brittle characteristics. The SiOC coatings prepared at high temperatures had thick, polycrystalline (low elastic modulus), loose, and resilient structures, thus exhibiting higher oxidation resistance.