Preparation and characterization of SiO2 thin film and SiC nanofibers to improve of graphite oxidation resistance

In this study, a multiphase coating was prepared on a graphite substrate by a two-step technique to improve oxidation resistance of graphite. The first step was to prepare a functionally graded SiC layer by a pack cementation process and the second step was to obtain a nano SiC and SiO2 thin film coating by a slurry painting technique. The microstructure and the surface chemistry of the coating were characterized by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The spectral deconvolution was conducted using CasaXPS software based on Gaussian-Lorentzian function. The isothermal oxidation test of the coated samples was performed at 1773 K for 10 h. A 500 μm thick graded C-SiC layer was observed at the graphite-coating interface. An amorphous SiO2 thin film and SiC nanofibers with the diameter in the range of 30-75 nm were formed on the coatings. The SiC nanofibers can efficiently improve oxidation resistance of graphite.