The Synthesis Methods Of Silicon Carbide Powder Mainly Include:

Acheson method, direct chemical method, thermal decomposition method and gas phase reaction method. Among them, in actual industrial production, the most popular method is the Acheson method.

The Acheson method is the most widely used synthesis method in industry. The method of α-SiC powder is to use electric heating to heat the mixture of quartz sand and coke to a high temperature of about 2500 ° C to make it react: SiO2(s)+3C(s)→α-SiC(s)+2CO (g). The silica raw material can be selected from fused silica sand or broken quartzite, and the carbon can be prepared from graphite, petroleum coke or ashless anthracite, adding NaCl and wood chips as additives, and generally reacting and synthesizing in an electric arc furnace at 2000-2400 °C. The whole reaction furnace is composed of movable refractory bricks, 10-20m in length, 3-4m in width and height, and can accommodate 400t graphite electrodes, which are placed at both ends and generate high temperature after electrification. Due to the large size of the entire electric arc furnace during the reaction process, the distribution of the temperature field is not uniform, and the center temperature is much higher than the furnace wall temperature, which results in the non-uniformity of the products in the production zone of the silicon carbide synthesis furnace, and there are often impure substances,The product at the core is pure green silicon carbide, with many impurities outside, generally iron, aluminum, carbon, etc., so the color is black (the reason is that the quartz sand and coke used for synthesis usually contain metal impurities such as Al and Fe), so the obtained SiC generally has a small amount of impurities in solid solution. Among them, the less impurity content is green, which is called green silicon carbide; the impurity content is black, which is called black silicon carbide).