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Pure silicon carbide is a colorless and transparent crystal. Industrial silicon carbide is pale yellow, green, blue or even black due to the type and content of impurities, and its transparency varies with its purity. Silicon carbide industrially produced in China 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 2840-3320kg/mm2.

Silicon carbide crystal growth process Pure silicon carbide is a colorless and transparent crystal. Industrial silicon carbide is pale yellow, green, blue or even black due to the type and content of impurities, and its transparency varies with its purity. Silicon carbide industrially produced in China 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 2840-3320kg/mm2.

The crystal structure of silicon carbide is divided into hexagonal or rhombohedral α-SiC and cubic β-SiC (called cubic silicon carbide). α-SiC constitutes many different variants due to the different stacking sequences of carbon and silicon atoms in its crystal structure, more than 70 species have been discovered. β-SiC transforms into α-SiC when the temperature is above 2100°C. The industrial method of silicon carbide is to use high-quality quartz sand and petroleum coke to refine it in a resistance furnace. The smelted silicon carbide blocks are crushed, washed with acid and alkali, magnetic separation and sieving or water separation to produce products of various particle sizes.

SiC is a stable compound of C and Si, and its lattice structure consists of two sublattices that are densely arranged, and each Si (or C) atom is bound to the surrounding C (Si) atom by directional strong tetrahedral sp3 bonds , Although the tetrahedral bond of SiC is strong, the stacking fault formation energy is very low, which determines the polytype phenomenon of SiC. It has been found that SiC has more than 250 polytypes, and the C/ The stacking order of the Si diatomic layers is different.