In-situ synthesis of SiC nanofibers for improving the oxidation resistance of graphite

In order to improve the oxidation resistance of graphite, a SiC/ZrO2-SiC nanofibers multiphase coating was developed on a graphite substrate using the pack cementation and slurry painting techniques. The microstructure of the coating was characterized by X-ray diffraction and scanning electron microscopy. The HSC chemistry software package was used for the thermodynamic calculations. The isothermal oxidation test of the coated samples was performed at 1773 K in air. A 500 µm thick gradient C-SiC transition layer was formed at the graphite-coating interface SiC nanofibers with the diameter in the range of 32-88 nm were observed on the coating whose growth was ascribed to the gas phase reaction of SiO with CO. The oxidation test results revealed that the SiC nanofibers and thermally stable phase ZrSiO4 were the mainly effective tools protecting graphite from oxidation.