Improvement in oxidation properties of SiC-coated carbon/carbon composites through modification of the SiC/carbon interface

To improve the oxidation resistance of C/C composites, SiC coating was prepared on the mild-oxidized composites by pack cementation method. Through short time mild-oxidation at 800 °C-1100 °C, thick transition coating could be obtained at interface and minimize the mismatch of thermal expansion coefficient (CTE) between SiC coating and C/C composites. The oxidation resistance of SiC coating was improved obviously, owing to the decrease of crack size. After 14 h oxidation at 1500 °C, the sample mild-oxidized at medium temperature with SiC coating still gained weight 0.3%, but the bending strength was only 83.7% of original strength. However, the bending strength of sample mild-oxidized at high temperature with SiC coating increased by 17.2%.