silicon carbide material structure
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 changes with the purity. The crystal structure of silicon carbide is divided into hexagonal or rhombic α - SiC and cubic β - SiC (called cubic silicon carbide).
Due to the different stacking order of carbon and silicon atoms in its crystal structure, α - SiC has formed many different variants, and more than 70 kinds have been found. β - SiC is transformed into α - SiC at 2100 ℃ and above. The industrial process of silicon carbide is refined in resistance furnace with high quality quartz sand and petroleum coke. After crushing, acid and alkali washing, magnetic separation, screening or water separation, the refined silicon carbide block is made into products with various particle sizes.
The energy consumption and energy consumption of silicon carbide smelting technology reach the world level. The quality level of black and green silicon carbide blocks is also world-class. The gap between China's SiC and the world's advanced level is mainly concentrated in four aspects
First, large-scale mechanical equipment is rarely used in the production process, and many processes are completed manually, so the per capita output of silicon carbide is low;
Second, the quality management of granular sand and fine powder products in deep-processing silicon carbide products is not fine enough, and the product quality stability is not enough.
Third, there is a certain gap between the performance indicators of some leading-edge products and those of developed countries.
Fourth, the direct emission of carbon monoxide in smelting process. The main foreign enterprises have basically realized closed smelting, while China's silicon carbide smelting is almost open smelting, and all carbon monoxide is discharged directly.