Guo-Dong Sun

A Cr–Al–Si oxidation resistant coating for carbon/carbon composites by slurry dipping

A Si-Al-Ir oxidation resistant coating was prepared for SiC coated carbon/carbon composites by slurry dipping. The phase composition, microstructure and oxidation resistance of the as-prepared Si-Al-Ir coating were studied by XRD (X-ray difiraction), SEM (scanning electron microscopy), and isothermal oxidation test at 1773 K in air, respectively. The surface of the as-prepared Si-Al-Ir coating was dense and the thickness was approximately 100 „m. Its anti-oxidation property was superior to that of the inner SiC coating. The weight loss of SiC/SiAl-Ir coated carbon/carbon composites was less than 5 wt. pct after oxidation at 1773 K in air for 79 h. The local oxidation defects in the coating may result in the failure of the SiC/Si-Al-Ir coating.

THE INFLUENCE OF SiC COATING PROCESS ON THE PROPERTIES OF C/C COMPOSITES

SiC coating for carbon/carbon composites was prepared by pack cementation method. The effects of coating process on the microstructure and the mechanical properties of C/C composites were analyzed by SEM and three-point bending test, respectively. As the infiltrated Si improved the interfaces bonding during the coating process, the flexural strength and flexural modulus of SiC-coated carbon/carbon composites were both increased by about 10% than the naked C/C composites. In addition, the mechanism of the change of failure mode of SiC coated C/C composites and naked C/C composites was addressed.