尊龙凯时

Silicon Carbide (SiC) is made of quartz sand, petroleum coke (or coal coke), wood chips as raw materials through high temperature smelting resistance furnace. Silicon carbide is also found in nature as a rare mineral, Moissanite. Silicon carbide is also known as moissanite. In contemporary C, N, B and other non-oxide high-tech refractory materials, silicon carbide is the most widely used, the most economic one. Silicon carbide can also be called gold steel sand or refractory sand. Silicon carbide is made of quartz sand, petroleum coke (or coal coke), wood chips (production of green silicon carbide needs to add salt) and other raw materials in the resistance furnace by high temperature smelting. At present, our industrial production of silicon carbide is divided into black silicon carbide and green silicon carbide two kinds, are hexagonal crystal, specific gravity is 3.20 ~ 3.25, microhardness is 2840 ~ 3320kg/mm2.

Including black silicon carbide and green silicon carbide, black silicon carbide is quartz sand, petroleum coke and high quality silica as the main raw material, through resistance furnace high temperature smelting. Its hardness between corundum and diamond, mechanical strength is higher than corundum, crisp and sharp. Green silicon carbide is made of petroleum coke and high quality silica as the main raw materials, adding salt as additives, and smelting by resistance furnace at high temperature. Its hardness is between corundum and diamond, and its mechanical strength is higher than corundum. Commonly used silicon carbide abrasive has two different crystals, one is green silicon carbide, containing SiC more than 97%, mainly used for grinding hard gold-containing tools. Another is black silicon carbide with metallic luster, and containing SiC more than 95%, strength than green silicon carbide, but the hardness is low, mainly used for grinding cast iron and non-metallic materials.

Properties of Silicon Carbide

The molecular formula is SiC, its hardness is between corundum and diamond, mechanical strength is higher than corundum, can be used as abrasive and some other industrial materials. Industrial silicon carbide developed in 1891, is the earliest artificial abrasive. Although small amounts of silicon carbide exist in meteorites and the Earth's crust, no available mineral source has been found so far.

Pure silicon carbide is a colorless and transparent crystal.Industrial silicon carbide because of the difference of the kinds and contents of impurities, so it will appear light yellow, green, blue and even black. Transparency varies with its purity. Silicon carbide crystal structure is divided into hexagonal or rhombic α-sic and cubic β-sic (called cubic silicon carbide). Due to the different stacking sequence of carbon and silicon atoms in α-sic crystal structure, there are many different variants, and more than 70 varieties have been found. β-sic is converted to α-sic at 2100℃.

The industrial process of silicon carbide is refined with high quality quartz sand and petroleum coke in a resistance furnace. The refined silicon carbide block, after crushing, acid and alkali washing, magnetic separation and screening or water separation and made into a variety of particle size products.

Silicon carbide has black silicon carbide and green silicon carbide two common basic varieties, they all belong to α-SIC. ①Black silicon carbide containing SiC about 98.5%, its toughness is higher than green silicon carbide, mostly used for processing low tensile strength materials, such as glass, ceramics, stone, refractory materials, cast iron and non-ferrous metals. ② Green silicon carbide containing SiC more than 99%, good self-sharpening, mostly used for processing hard alloy, titanium alloy and optical glass, but also used for honing cylinder liner and fine grinding high speed steel tool. In addition, there is cubic silicon carbide, which is a yellow-green crystal made by a special process. The abrasive tools used for production are suitable for ultra-finishing bearing, and the surface roughness can be processed from Ra32 ~ 0.16 micron to Ra0.04 ~ 0.02 micron at a time.

Silicon carbide due to stable chemical properties, high thermal conductivity, small coefficient of thermal expansion, good wear resistance, in addition to abrasive, there are many other uses, such as: in a special process to the silicon carbide powder coated in the inner wall of the turbine impeller or cylinder body, can improve its wear resistance and prolong the service life of 1~2 times; advanced refractory material made of silicon carbide, with heat shock, small size, light weight and high strength, good energy saving effect. Low grade silicon carbide (containing SiC about 85%) is an excellent deoxidizer, with it can speed up steel making speed, and easy to control the chemical composition, improve the quality of steel. In addition, silicon carbide is also widely used in the production of electric heating element silicon carbon rod.

Silicon carbide hardness is very large, and has excellent thermal conductivity. It’s also a semiconductor, at high temperature can resist oxidation.

Application of Silicon Carbide

(1) As abrasive, can be used to do abrasive tools, such as grinding wheel, whetstone, grinding head, sand tile, etc.

(2) As a metallurgical deoxidizer and high temperature resistant material.
Silicon carbide has four main application areas, namely: functional ceramics, high-grade refractory materials, abrasives and metallurgical raw materials. At present, raw silicon carbide can be supplied in large quantities, which is not a high-tech product. However, the application of nanometer silicon carbide powder with very high technical content cannot form scale economy in a short time.

(3) High purity single crystal, can be used to manufacture semiconductors and silicon carbide fiber.
Main applications: Used for 3-12 inch monocrystalline silicon, polycrystalline silicon, potassium arsenide, quartz crystal wire cutting.Solar photovoltaic industry, semiconductor industry, piezoelectric crystal industry engineering processing materials.

Abrasives and Grinding Tools

It is mainly used for grinding and polishing of grinding wheel, sandpaper, belt, whetstone, grinding block, grinding head, grinding paste, monocrystalline silicon and polycrystalline silicon in photovoltaic products and piezoelectric crystal in electronic industry.

Chemical Engineering

Silicon carbide can be used as a deoxidizer for steelmaking and as a modifier for cast iron organization. It can be used as a raw material for the manufacture of silicon tetrachloride. It is also the main raw material for the silicone resin industry. Silicon carbide deoxidizer is a new kind of compound deoxidizer, replaced the traditional solid silicon powder carbon powder, and compared with the original process of various physical and chemical performance is more stable, deoxidization effect is good, deoxidize shorter time, save energy and improve the efficiency of steel, improve the quality of steel, reduce raw material consumption, reduce environmental pollution, improve working conditions, It is of great value to improve the comprehensive economic benefit of electric furnace.

Wear, Fire and Corrosion Resistant Materials

The use of silicon carbide has corrosion resistance, high temperature resistance, high strength, good thermal conductivity, impact resistance and other characteristics, silicon carbide on the one hand can be used for all kinds of smelting furnace lining, high temperature furnace members, silicon carbide plate, lining board, strutting piece, sagger, silicon carbide crucible, etc.

On the other hand, it can be used for high temperature indirect heating materials of non-ferrous metal smelting industry, such as vertical tank distillation furnace, distillation furnace tray, aluminum electrolyzer, copper melting furnace lining, zinc powder furnace arc plate, thermocouple protection tube, etc.; used for making wear resistance, corrosion resistance, high temperature resistance and other advanced silicon carbide ceramic materials;silicon carbide can also make rocket nozzle, gas turbine blade, etc. In addition, silicon carbide is also one of the ideal materials for highway, aviation runway solar water heater.

Non-Ferrous Metals

The use of silicon carbide has high temperature resistance, high strength, good thermal conductivity, impact resistance, as high temperature indirect heating materials, such as solid tank distillation furnace, distillation furnace tray, aluminum electrolytic tank, copper melting furnace lining, zinc powder furnace arc plate, thermocouple protection tube.

Steel

Using the characteristics of silicon carbide corrosion resistance, thermal shock resistance, wear resistance, good thermal conductivity, used in large blast furnace lining to improve the service life.

Metallurgical Beneficiation

Silicon carbide hardness is second only to diamond, with strong wear-resisting performance, is wear-resisting pipeline, impeller, pump chamber, whirlcone, ore bucket lining ideal material. Its wear resistance is 5--20 times of the service life of cast iron and rubber, and it is also one of the ideal materials for aviation flight runway.

Building Materials Ceramic Grinding Wheel Industry

Make use of its characteristic thermal conductivity, heat radiation, high heat intensity characteristics to manufacture sheet kiln furniture. This can not only reduce the capacity of kiln furniture, but also improve the kiln capacity and product quality, shorten the production cycle. Silicon carbide is an ideal indirect material for baking and sintering ceramic glazes.

Energy Conservation

Using good thermal conductivity and thermal stability as heat exchanger, burn up is reduced, fuel is saved by 35%, productivity is increased by 20-30%. In particular, the mine concentrator with the discharge pipeline put in, its wear-resisting degree is 6- 7 times of the ordinary wear-resisting material.

Abrasive particle size and its composition according to GB/ T2477-83. Abrasive particle size composition determination method according to GB/ T2481-83.

Jewelry

Synthetic silicon carbide (Synthetic Moissanite) also known as Synthetic Moissanite, Synthetic carbon silicate (chemical composition SiC).0.104 dispersion is bigger than diamond (0.044), refractive index 2.65-2.69(diamond 2.42), with the same diamond luster with diamond ,“fire color" stronger than diamond.It is closer to a diamond than any previous imitation.It is manufactured by C3 company in north Carolina,USA. It has the patent of synthetic silicon carbide production in various countries and is being applied to the world.