Oxidation resistance of silicon carbide
Silicon Carbide is produced at high temperature in an electric resistance type furnace with quarts sand and petroleum coke as its main raw materials. Its hardness is between fused alumina and synathetic diamond. Mechanical intensity of it is hig-her than fused alumina.it is brittle and sharp and has electrical and heat conductivity in some degree.
The most important of the chemical properties of silicon carbide is its oxidation resistance. When silicon carbide is heated in the air to above 1000 ℃, it will only oxidize on its surface to form a silicon dioxide film, which makes silicon carbide have better properties. Antioxidant properties. At 1300°C, cristobalite begins to precipitate in the silicon dioxide of the thin film layer, and the transformation of the crystal form causes the thin film layer to crack, thereby increasing the oxidation rate. At 1500 to 1600°C, the thickening of the SiO2 layer limits the oxidation effect, which enables the SiC to be used stably at a high temperature of 1600°C for a long time.