EFFECT OF SIC NANOFIBERS ON THE OXIDATION RESISTANCE OF GRAPHITE

In an attempt to improve the oxidation resistance of graphite, a coating containing SiC nanofibers was developed on a graphite substrate using the pack cementation and slurry painting techniques at 1600 °C temperature. The microstructure of the coating was characterized by X-ray diffraction and scanning electron microscopy. The thermal shock tests of the coated samples were accomplished at 1500 °C. Results show that a gradient C–SiC transition layer with about 500 μm in thickness was formed at the graphite-coating interface. SiC nanofibers with the diameter in the range of 30-70 nm were detected on the coating whose growth was attributed to the gas phase reaction of SiO with CO. The oxidation test results discovered that the SiC nanofibers serve an important role in the oxidation resistance so that the mass loss of the secondary coating with SiC nanofibers was 17% compared to 72% for the initial coating without SiC nanofibers.