The black color of silicon carbide is due to the tiny carbon particles wrapped in the crystal. When no salt is added, due to the fast evaporation rate of silica, the carbonaceous material has no time to react with it, causing a part of the silica vapor to escape and lose, but the carbonaceous material has not completely evaporated, leaving behind in the form of fine particles. In the silicon carbide crystals that have been formed.
In the process of producing green silicon carbide, we often say that one more element is table salt than when black silicon carbide is smelted, because table salt can promote the green appearance of silicon carbide products. However, after a long period of extensive experiments, some manufacturers have found that in the process of smelting green silicon carbide, pure green silicon carbide cannot be smelted when there are many impurities in the raw materials (aluminum, calcium, magnesium, boron, etc.). Conversely, if the purity of raw materials is too high, bright green silicon carbide can be smelted without adding salt.
Sometimes the process of smelting green carbide silicon and adding table salt will also have some side effects, which are to increase the leakage of furnace material and furnace body, and aggravate the corrosion of equipment and workshops. Therefore, in the process of smelting silicon carbide, more attention should be paid to the use of table salt.
Regarding the reason for the color of silicon carbide, we also need to further study the differences in the process of smelting silicon carbide from different manufacturers, so the color and content of silicon carbide will also have certain differences.