The hardness of Boron carbide is black crystal Bai, which is second only to the gold du corundum. The zhi Mo type hardness is 9.36, the solution point is 2450, and the specific gravity is 2.51g/ 3. The artificial cubic boron nitride is the hardest, mohs hardness is 9+, which is not as hard as diamond.

The hardness of silicon carbide is only DU secondary to diamond, so silicon carbide is hard zhi.

Silicon carbide (SiC) is made of quartz sand petroleum coke (or coal coke) wood chips (salt is needed to produce green silicon carbide) and other raw materials by high temperature smelting through resistance furnace. There is also a rare mineral in nature, mosanite.

Silicon carbide, also known as carbon silica, is one of the most widely used and economical non-oxide high-tech refractory materials such as C, N and B, which can be called gold and steel sand or refractory sand.

At present, China's industrial production of silicon carbide is divided into black silicon carbide and green silicon carbide, both of which are hexagonal crystals, with a specific gravity of 3.20~3.25, and a microhardness of 2,840 ~ 3,320 kg/mm2.