nature
The molecular formula is SiC. Its hardness is between corundum and diamond, and its mechanical strength is higher than corundum. It can be used as abrasive and some other industrial materials. 189 1 successfully developed industrial silicon carbide, which is the earliest artificial abrasive. Although there is a small amount of silicon carbide in meteorites and the earth's crust, no exploitable mineral source has been found so far. Pure silicon carbide is colorless and transparent crystal. Industrial silicon carbide is light yellow, green, blue or even black due to different kinds and contents of impurities, and its transparency varies with purity. The crystal structure of silicon carbide can be 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 forms many different variants, and more than 70 kinds have been found so far. Above 2 100℃, β-SiC is transformed into α-SiC
The industrial production method of silicon carbide is refining with high-quality quartz sand and petroleum coke in a resistance furnace. The smelted silicon carbide blocks are made into products with various particle sizes through crushing, acid-base washing, magnetic separation, screening or water separation. There are two commonly used basic varieties of silicon carbide, black silicon carbide and green silicon carbide, both of which belong to α-SiC. ① Black silicon carbide contains about 98.5% SiC, and its toughness is higher than that of green silicon carbide. It is mostly used to process materials with low tensile strength, such as glass, ceramics, stone, refractories, cast iron, nonferrous metals, etc. ② Green silicon carbide contains more than SiC99%%, and has good self-sharpening. It is mostly used for machining cemented carbide, titanium alloy, optical glass, honing cylinder liners and grinding high-speed steel tools. In addition, there is cubic silicon carbide, which is a yellow-green crystal prepared by a special process. The abrasive tool used for manufacturing is suitable for ultra-precision machining of bearings, and the surface roughness can be machined to Ra32 ~ 0. 16 micron to Ra0.04~0.02 micron at one time. Silicon carbide has many other uses besides abrasives because of its stable chemical properties, high thermal conductivity, small thermal expansion coefficient and good wear resistance. If silicon carbide powder is coated on the inner wall of turbine impeller or cylinder by special process, its wear resistance can be improved and its service life can be extended by 1 ~ 2 times. Advanced refractories made of it have the advantages of thermal shock resistance, small volume, light weight, high strength and good energy saving effect. Low-grade silicon carbide (containing about 85% SiC) is an excellent deoxidizer, which can speed up steelmaking, control chemical composition and improve steel quality. In addition, silicon carbide is also widely used to manufacture silicon carbide rods for electric heating elements. Silicon carbide has great hardness and excellent thermal conductivity. It is a semiconductor, which can resist oxidation at high temperature.
The purpose of editing this paragraph
(1) can be used as abrasive, such as grinding wheel, whetstone, grinding head, sand tile, etc. (2) As metallurgical deoxidizer and high temperature resistant material. Silicon carbide has four main application fields, namely: functional ceramics, advanced refractories, abrasives and metallurgical raw materials. At present, crude silicon carbide can be supplied in large quantities, which is not a high-tech product, and the application of nano silicon carbide powder with high technical content cannot form economies of scale in a short time. (3) High-purity single crystals can be used to manufacture semiconductors and silicon carbide fibers. Main uses: used for wire cutting of 3- 12 inch monocrystalline silicon, polycrystalline silicon, potassium arsenide, timely crystal, etc. Engineering processing materials for solar photovoltaic industry, semiconductor industry and piezoelectric crystal industry.
abrasive
Mainly used for grinding and polishing grinding wheels, sandpaper, abrasive belts, oilstones, grinding blocks, grinding heads, grinding pastes, monocrystalline silicon, polycrystalline silicon and piezoelectric crystals in the electronic industry.
chemical industry
It can be used as deoxidizer for steelmaking and improver for cast iron structure, and also can be used as raw material for manufacturing silicon tetrachloride, which is the main raw material of silicone resin industry. Silicon carbide deoxidizer is a new powerful compound deoxidizer, which replaces the traditional silicon powder carbon powder for deoxidization. Compared with the original process, the physical and chemical properties are more stable, the deoxidation effect is good, the deoxidation time is shortened, the energy is saved, the steelmaking efficiency is improved, the steel quality is improved, the consumption of raw and auxiliary materials is reduced, the environmental pollution is reduced, the working conditions are improved, and the comprehensive economic benefits of the electric furnace are improved.
Wear-resistant, fire-resistant and corrosion-resistant materials
Silicon carbide has the characteristics of corrosion resistance, high temperature resistance, high strength, good thermal conductivity and impact resistance. On the one hand, silicon carbide can be used for various smelting furnace linings, high-temperature furnace parts, silicon carbide plates, linings, supports, saggers, silicon carbide crucibles and the like. On the other hand, it can be used for high-temperature indirect heating materials in nonferrous metal smelting industry, such as vertical tank distillation furnace, distillation furnace tray, aluminum electrolytic cell, copper smelting furnace lining, arc plate for zinc powder furnace, thermocouple protection tube and so on. Used for manufacturing advanced silicon carbide ceramic materials with wear resistance, corrosion resistance and high temperature resistance; It can also be used to make rocket nozzles and gas turbine blades. In addition, silicon carbide is also one of the ideal materials for solar water heaters on expressways and airstrips.
nonferrous metal
Using the high temperature resistance of silicon carbide; Def is strong &; Def has good thermal conductivity &; Def impact resistance &; Def as a high temperature indirect heating material &; Def such as retort &; Def distillation column plate; Aluminum electrolytic cell; Def copper melting furnace lining &; Def zinc powder furnace arc plate and def thermocouple protection tube, etc.
steel
Using the corrosion resistance of silicon carbide &: Def is resistant to thermal shock and wear &; Def has good thermal conductivity &; Def is used for lining of large blast furnace to improve service life.
Metallurgical beneficiation
The hardness of silicon carbide is second only to that of diamond &; Def has strong wear resistance &; Def is a kind of wear-resistant pipeline &; Def impeller, combustion chamber and cyclone separator & ideal materials for DEF hopper lining. The wear resistance of def is 5-20 times that of cast iron and rubber. Def is also one of the ideal materials for aviation flight runway.
Building materials ceramic grinding wheel industry
Using its thermal conductivity and thermal radiation &; High thermal strength of def&; Def manufacturing plate kiln furniture &; Def can not only reduce the capacity of kiln furniture &; Def also improves the loading capacity and product quality of the kiln & Def shortens the production cycle &; Def is an ideal indirect raw material for firing and sintering ceramic glaze.
conservation of energy
Using good thermal conductivity and thermal stability &; Def as a heat exchanger &; Def fuel consumption is reduced by 20%&; Def saves fuel by 35%&; Def has increased productivity by 20-30%&; Def, especially the internal layout of the discharge pipeline of the mine concentrator &; The wear resistance of def is 6-7 times that of ordinary wear-resistant materials. ② The abrasive particle size and composition conform to GB/T 2477-83. The determination method of abrasive particle size composition is GB/T 248 1-83.
jewels
Synthetic silicon carbide, also known as synthetic Mosanite and synthetic moissanite (chemical composition SiC), has a dispersion of 0. 104 greater than that of diamond (0.044) and a refractive index of 2.65-2.69 (2.42 of that of diamond), which has the same diamond luster and stronger "fire color" and is closer to diamond than any previous imitation. This is made by C3 Company in North Carolina, USA. It has patents for the production and synthesis of silicon carbide in all countries of the world and is being popularized and applied all over the world.