The molecular formula of silicon carbide is SiC, its hardness is between that of corundum and diamond, its mechanical strength is higher than that of corundum, and it can be used as abrasive and some other industrial materials.
Pure silicon carbide is a colorless and transparent crystal. Due to the different types and contents of impurities, industrial silicon carbide is light yellow, green, blue or even black, and its transparency varies with its purity. The crystal structure of silicon carbide is divided into hexagonal or rhombohedral α-SiC and cubic β-SiC (called cubic silicon carbide).
Silicon carbide has two commonly used basic varieties, black silicon carbide and green silicon carbide, both of which belong to α-SiC. ① Black silicon carbide contains about 98.5% SiC, and its toughness is higher than that of green silicon carbide. It is mostly used for processing materials with low tensile strength, such as glass, ceramics, stone, refractory materials, cast iron and non-ferrous metals. ②Green silicon carbide contains more than 99% SiC and has good self-sharpening properties. It is mostly used for processing hard alloys, titanium alloys and optical glass, and is also used for honing cylinder liners and fine grinding high-speed steel tools. In addition, there is cubic silicon carbide, which is a yellow-green crystal produced by a special process. The abrasive tools used to make it are suitable for superfinishing of bearings, and can make the surface roughness from Ra32～0.16 micron to Ra0.04～ 0.02 microns.
Silicon carbide is very hard and has excellent thermal conductivity. It is a semiconductor and can resist oxidation at high temperatures.
1) As an abrasive, it can be used to make abrasive tools, such as grinding wheels, oil stones, grinding heads, sand tiles, etc.
(2) As metallurgical deoxidizer and high temperature resistant material.
Silicon carbide mainly has four major application areas, namely: functional ceramics, advanced refractories, abrasives and metallurgical raw materials. At present, silicon carbide coarse material can be supplied in large quantities, and it cannot be regarded as a high-tech product, but the technical content is extremely high
The application of nano-scale silicon carbide powder cannot form economies of scale in a short time.
(3) High-purity single crystals can be used to manufacture semiconductors and silicon carbide fibers.