Black silicon carbide is a hexagonal crystal with a microhardness of 2840-3320kg/mm2 and a specific gravity of 3.20-3.25. If it is pure black silicon carbide, it should be a colorless and transparent crystal. However, industrial black silicon carbide will appear black because it contains impurities.
After smelting, black silicon carbide blocks are obtained, which need to go through processes such as crushing, acid and alkali washing, magnetic separation and screening or water separation to make various particle sizes.
1. The SiC content of black silicon carbide is about 98.5%. Its toughness is higher than that of green silicon carbide, so it is more suitable for processing materials with low tensile strength such as glass, ceramics, stone, refractory materials, cast iron and non-ferrous metals.
2. The SiC content of green black silicon carbide is more than 99%, and its self-sharpening is very good. It is often used to process cemented carbide, titanium alloy and optical glass. It is also suitable for honing cylinder liners and fine grinding high-speed steel tools.
A yellow-green crystal made by a special process is cubic silicon carbide. This category is suitable for making abrasive tools and can be used for ultra-fine processing of bearings. Generally, the surface roughness of the workpiece can be processed from Ra32-0.16 microns to Ra0.04-0.02 microns at one time.
Black silicon carbide has good chemical stability, high thermal conductivity, small thermal expansion coefficient, and very good wear resistance, so it can not only be used as an abrasive, but also for other purposes. For example: coating black silicon carbide powder on the inner wall of the turbine impeller or cylinder body can improve the wear resistance of the processed workpiece and extend the service life of the workpiece by 1-2 times; because it has good thermal shock resistance, small size, light weight, high strength, and is particularly energy-saving, it can be made into high-grade refractory materials.
Low-grade black silicon carbide is an excellent deoxidizer, which can speed up steelmaking and improve the quality of steel. In addition, black silicon carbide can also be made into electric heating elements-silicon carbon rods. Black silicon carbide is a good semiconductor material because of its high hardness and good thermal conductivity.
