Fabrication Technology Of Silicon Carbide

                 Silicon carbide is mostly man-made because of its low natural content. The common method is to mix quartz sand with coke, use one of the silica and petroleum coke, add salt and sawdust, put into the electric furnace, heat to 2000°c temperature, after a variety of chemical process to obtain sic powder.Silicon Carbide

                  SIC (sic) is an important abrasive because of its great hardness, but its application range is more than that of general abrasive. For example, it has high temperature resistance, thermal conductivity and become a tunnel kiln or shuttle kiln, one of the preferred kiln materials, it has the conductivity of an important electrical heating elements. SIC products should be prepared first by SIC smelting block [or said: sic granular material, because it contains C and superhard, so sic granular material has been called: Emery. But note: It is different from natural carborundum (also known as Garnet). In industrial production, sic smelting blocks are usually quartz, petroleum coke as raw materials, auxiliary recovery materials, spent materials, through grinding and other processes to become a reasonable proportion of the appropriate size and granularity (in order to adjust the permeability of the burden of the need to add a proper amount of sawdust, the preparation of green silicon carbide should be added to the amount of salt) by high-temperature preparation. The thermal equipment for preparing SIC smelting blocks at high temperature is a special silicon carbide furnace, the structure consists of an end wall with electrodes, a detachable side wall and a furnace body (full name: Electric heating body in the center of the Furnace), generally with graphite powder or petroleum coke in a certain shape and size installed in the center of the burden, generally circular or rectangular. The ends are connected with the electrodes). The furnace used in the firing method commonly known as: Buried powder firing. It is heated to start, the furnace body temperature of about 2,500 ℃, or even higher (2600~2700℃), the burden of 1450 ℃ when the beginning of the synthesis of sic (but SIC is mainly formed in ≥1800℃), and release Co. However, SIC will decompose when ≥2600℃, but the decomposed SI will be formed with the C sic in the charge. Each group of electric furnaces is equipped with a set of transformers, but the production of only a single electric furnace power supply, in order to adjust the voltage according to the electrical load characteristics to basically maintain constant power, high-power electric furnace to heat about the "H," after the power failure to generate SIC reaction is basically over, and after a period of cooling can be removed from the side wall, and then gradually Silicon Carbide

              After the high-temperature calcination of the charge from the outside to the inside is: the raw material (in the Furnace heat preservation role), Oxygen silicon carbide astoria (semi-reactive material, the main component is C and Sio. ), adhesive layer (is a tightly bonded material layer, the main components are C, SiO2, 40%~60%sic and Fe, AL, CA, MG carbonate), amorphous material layer (the main component is 70%~90%sic, and is cubic sic namely β-sic, the rest is C, SiO2 and Fe, A1, CA, MG carbonate), two grade product SIC layer (the main ingredient is 90%~95%sic, the layer has produced six square sic, namely mouth one sic, But the crystal is small, very fragile, can not be used as abrasive), the first grade SIC layer (sic content is 96%, and is six square sic is the mouth of a coarse crystal), furnace core graphite. In each of the above layers, the reactants and a portion of the oxide silicon carbide layer are usually collected as spent materials, the other part of the oxygen silicon carbide layer is collected with amorphous, two grade, and some binders as the recycled material, while some bonding is very tight, the block degree is large, impurities are more than the binder. The first grade is graded, coarse crushing, fine, chemical treatment, drying and sieving, magnetic separation becomes a variety of particle size of black or green sic particles. To be made into SIC powder also through the process of water selection, to be made into silicon carbide products also through the process of forming and burning.Silicon Carbide