Preparation and oxidation resistance of SiC-coated graphite powders via microwave-assisted molten salt synthesis

Silicon carbide (SiC)-coated graphite composite powders was synthesized at 1423 K by a microwave-assisted molten salt synthesis, using graphite flakes and silicon powders as raw materials. The phase composition, morphology and microstructure of the coated graphite were characterized by X-ray diffraction, field emission scanning electron microscopy and high resolution transmission electron microscopy. The results showed that the formation temperature of SiC coating which consisted of lots of nanofibers with hundreds nanometers in length and several tens in diameter was reduced for about 150 K compared with conventional molten salts method. The water wettability and oxidation resistance of as-prepared coated graphite were greatly enhanced owing to the existence of SiC coating. The apparent oxidation activation energy of the coated graphite was 168.3 kJ/mol, which was higher than that 157.4 kJ/mol for raw graphite.