Black silicon carbide is smelted with quartz sand, petroleum coke (or anthracite) and other raw materials in the 2600-2700 ℃ high temperature resistance furnace and then cooled so as to get the original black silicon carbide block, the original black silicon carbide block is crushed by the crusher, the ball mill continues to be finely ground to get fine powder. Take fine powder as raw material, use overflow tank to add a lot of water, rely on the buoyancy of water to control the time accurately, draw out different types of black silicon carbide micro-powder at different times, precipitation, high-temperature drying, sieve loose, and finally packaged into the warehouse.
This silicon carbide powders is black opaque hexagonal crystals, Mohs hardness is 9.2, second only to diamond and boron carbide, performance is brittle and sharp and has a certain conductivity. This silicon carbide powders contains SiC for more than 98.5%, its toughness is higher than the green silicon carbide, mostly used for processing materials with low tensile strength, such as glass, ceramics, stone, refractories, cast iron and non-ferrous metals, optical glass, ceramics and other non-metallic materials.
Black silicon carbide high temperature smelting firing method commonly known as: buried powder firing. It is a power that is the beginning of heating, the furnace core body temperature of about 2500 ℃, or even higher (2600 ~ 2700 ℃), the charge reaches 1450 ℃ when the beginning of the synthesis of SiC (but SiC is mainly in ≥ 1800 ℃ when the formation of), and the release of CO. However, the temperature is higher than 2600 ℃ when the SiC will be decomposed, but decomposition of the si and the charge in the SiC generation of C. Each group of furnaces with a Each group of electric furnaces is equipped with a set of transformers, but the production of only a single furnace power supply, in order to adjust the voltage according to the characteristics of the electrical load to maintain basically constant power, high-power electric furnace to be heated for about 24h, after the blackout of the reaction to generate SiC basically over, and then after a period of cooling can be removed from the side wall, and then gradually take out of the furnace charge. Preparation of this silicon carbide powders is mainly carried out through the smelting of quartz and petroleum tar under high temperature conditions, so the demand for temperature is high, if the temperature does not meet the demand will produce impurities, so the enterprise should be proficient in this technology.
