Question 2: What's the difference between silicon carbide and ceramics? The former is a ceramic with very high porosity, and the latter is a ceramic with very low porosity! The raw materials are the same!
Question 3: Is silicon carbide toxic? Silicon carbide has four main application fields, namely: functional ceramics, advanced refractories, abrasives and metallurgical raw materials. At present, (3) high-purity single crystals can be used to manufacture semiconductors and silicon carbide fibers. Silicon carbide is nontoxic. involve
Question 4: What is silicon carbide? Silicon carbide (SiC) is a ceramic compound composed of silicon and carbon. There is also a rare mineral in nature-mosan stone. There are at least 70 crystalline forms of silicon carbide. α -silicon carbide is the most common isomorphic substance, which is formed at a high temperature above 2000℃ and has a hexagonal crystal structure (similar to wurtzite). β -silicon carbide, cubic structure, similar to diamond, but the formation temperature is lower than 2000°c, the structure is shown in the attached page. Although the application of heterogeneous catalyst carrier has attracted people's attention because of its higher unit surface area than α type, this type has not been commercially applied until today. Because of its specific gravity of 3.2 and high sublimation temperature (about 2700°C), silicon carbide is very suitable as a raw material for bearings or high temperature furnaces. It will not melt under any pressure that can be reached, and its chemical activity is quite low. Because of its high thermal conductivity, high breakdown electric field strength and high maximum current density, many people have recently tried to use it instead of silicon in the application of semiconductor high-power devices. In addition, it has a strong coupling effect with microwave radiation, and all its high altitude points make it practical for heating metals. Pure silicon carbide is colorless, while brown to black in industrial production is due to iron-containing impurities. The iridescent luster on the crystal is caused by the protective layer of silicon dioxide produced on its surface. Uses: Semiconductors, lightning rods, circuit components, high-temperature applications, ultraviolet detectors, structural materials, astronomy, disc brakes, clutches, diesel particulate filters, filament pyrometers, ceramic membranes, cutting tools, heating elements, nuclear fuel, jewelry, steel, protective gear, catalyst carriers and other fields.
Question 5: What is silicon carbide and what is its function? According to the different use environment, silicon carbide products can be divided into many categories. Generally, it is more mechanical. If applied to mechanical seal, it can be called silicon carbide sealing ring, which can be divided into static ring, moving ring and flat ring. We can also make various shapes of silicon carbide products according to the special requirements of customers, such as silicon carbide special-shaped parts, silicon carbide plates, silicon carbide rings and so on.
Silicon carbide ceramics is one of the products of silicon carbide, which has the characteristics of high hardness, high corrosion resistance and high high temperature strength, making silicon carbide ceramics widely used.
Application in sealing ring: Silicon carbide ceramics have good chemical corrosion resistance, high strength, high hardness, good wear resistance, low friction coefficient and high temperature resistance, and are ideal materials for manufacturing sealing rings. When combined with graphite material, its friction coefficient is smaller than that of alumina ceramics and cemented carbide, so it can be used for high PV value, especially for transporting strong acid and alkali. The SIC- 1 sintered silicon carbide products produced by our company have the characteristics of high density, high hardness, large production batch and complex product shape, which are suitable for high-performance seals, especially high PV value and strong acid and alkali resistance. The SIC-3 silicon carbide ceramic products produced by our company are silicon carbide materials containing graphite. Because there are a large number of fine dispersed graphite particles in silicon carbide matrix, when it is used with other materials, its friction coefficient is very small and it has good self-lubricating performance, which is especially suitable for making gas seals or seals under dry friction conditions, thus improving the service life and working reliability of seals.
Question 6: Whether ceramic silicon carbide can withstand low temperature is mainly due to its excellent wear resistance, high temperature resistance and chemical corrosion resistance. It is difficult to see references about its low temperature resistance in the literature, but one thing is certain: silicon carbide material is applied in rocket technology, mainly by its high temperature resistance and wear resistance, but when the rocket passes through the atmosphere and the top of troposphere, the temperature there can reach -50-60℃, and the temperature difference changes greatly when it passes through the middle layer.
Question 7: Which is the wear resistance ZrO2 zirconia, zirconia and silicon carbide?
Zirconia mineral raw materials in nature mainly include baddeleyite and zircon. Zirconium is a kind of deep igneous mineral, which is light yellow, brown yellow, yellow-green and so on. , with a specific gravity of 4.6-4.7 and a hardness of 7.5, has a strong metallic luster and can be used as a raw material for ceramic glaze.
White heavy amorphous powder or monoclinic crystal, odorless and tasteless. Tetragonal crystals are formed above 1 100℃, and cubic crystals are formed above 1900℃. Generally, it often contains a small amount of hafnium dioxide, which melts with sodium carbonate to form sodium zirconate, and can be hydrolyzed into sodium hydroxide and zirconium hydroxide which are almost insoluble in water when it meets water. It was dissolved in 2 parts of sulfuric acid at 6900℃. Slightly soluble in hydrochloric acid and nitric acid, slowly soluble in hydrofluoric acid, almost insoluble in water. The relative density is 5.85, the melting point is 2680℃, the boiling point is 4300℃, the refractive index is 2.2, and the median lethal dose (abdominal cavity of mice) is 37mg/kg, which is * *.
carborundum
Silicon carbide (SiC) is made by melting quartz sand, petroleum coke (or coal coke) and sawdust in a resistance furnace at high temperature. Silicon carbide is also a rare mineral in nature, also known as moissanite. Among the non-oxide high-tech refractory materials such as carbon, nitrogen and boron, silicon carbide is the most widely used and economical one. It can be called diamond sand or refractory sand. Silicon carbide is made of quartz sand, petroleum coke (or coal coke), sawdust (salt is needed to produce green silicon carbide) and other raw materials by high temperature melting in a resistance furnace. At present, silicon carbide produced in China is divided into black silicon carbide and green silicon carbide, both of which are hexagonal crystals with specific gravity of 3.20 ~ 3.25 and microhardness of 2840 ~ 3325.
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 a small amount of silicon carbide exists in meteorites and the earth's crust, no mineral source has been found for mining.
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). Because of the different stacking order of carbon and silicon atoms in its crystal structure, α-SiC forms many different variants. Above 2 100℃, more than 70 kinds of β-SiC have been found to be transformed into α-SiC The industrial production method of silicon carbide is to extract silicon carbide blocks from high-quality quartz sand and petroleum coke in a resistance furnace, and then make products with various particle sizes through crushing, acid-base washing, magnetic separation screening or water separation.
There are two 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 95% 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 and nonferrous metals. ② Green silicon carbide contains about 97% SiC and has good self-sharpening, which is mostly used to process cemented carbide, titanium alloy and optical glass. It is also used for honing cylinder liners and grinding high-speed steel tools. In addition, there is cubic silicon carbide, which is a yellow-green crystal made 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 good 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 is a semiconductor with high hardness, good thermal conductivity and oxidation resistance at high temperature.
aluminium oxide
Also known as alumina, its molecular weight is 102, and it is usually called "alumina". It is a white amorphous powder, commonly known as bauxite.
White crystalline powder, odorless, tasteless, extremely hard, easy to absorb moisture and not deliquescent, soluble in concentrated sulfuric acid, slowly dissolved in alkaline solution to form hydroxide, almost insoluble in water and nonpolar organic solvents. The relative density (D204) is 4.0. The melting point is about 2000℃ ... >; & gt
Question 8: Is silicon carbide porous ceramics expensive? We are making silicon carbide ceramic matrix composites, and the price ranges from about 40,000 to about 65,438+10,000 per kilogram.
Question 9: What is the industry category of silicon carbide? Belonging to the smelting industry;
applied range
Silicon carbide has four main application fields, namely: functional ceramics, advanced refractories, abrasives and metallurgical raw materials. 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.
(1) as abrasive, can be used as abrasive tools, such as grinding wheel, whetstone, grinding head, sand tile, etc.
⑵ Used as metallurgical deoxidizer and high temperature resistant material.
(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.
It is used in the fields of semiconductors, lightning rods, circuit components, high-temperature applications, ultraviolet detectors, structural materials, astronomy, disc brakes, clutches, diesel particulate filters, filament pyrometers, ceramic membranes, cutting tools, heating elements, nuclear fuel, jewelry, steel, protective gear, catalyst carriers and so on.
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.
"Three-proof" 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
Silicon carbide has high temperature resistance, high strength, good thermal conductivity and impact resistance, and can be used as high-temperature indirect heating materials, such as retort, retort tray, aluminum electrolytic cell, copper melting furnace lining, arc plate for zinc powder furnace, thermocouple protection tube, etc.
steel
Using the characteristics of silicon carbide, such as corrosion resistance, thermal shock resistance, wear resistance and good thermal conductivity, it is used in the lining of large blast furnace to improve its service life.
Metallurgical beneficiation
The hardness of silicon carbide is second only to that of diamond, and its wear resistance is strong. It is an ideal material for wear-resistant pipes, impellers, combustion chambers, cyclones and hoppers, and its wear resistance 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 characteristics of high thermal conductivity, heat radiation and high heat intensity, manufacturing thin-plate kiln furniture can not only reduce the volume of kiln furniture, but also improve the loading capacity and product quality of kiln and shorten the production cycle. It is an ideal indirect raw material for firing and sintering ceramic glaze.
conservation of energy
Using good thermal conductivity and thermal stability as a heat exchanger can reduce fuel consumption by 20%, save fuel by 35% and improve productivity by 20-30%, especially for the internal placement of discharge pipes in mine concentrator, and its wear resistance is 6-7 times that of ordinary wear-resistant materials.
Abrasive particle size and its 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. ...& gt& gt
Question 10: Which is more wear resistant, silicon carbide ceramics or alumina ceramics? Alumina ceramics are more wear-resistant.
The ball-milled pebbles in our ceramic factory are all made of high-alumina pebbles to grind natural gravel, which is very wear-resistant. Moreover, alumina enhances the mechanical strength and hardness of ceramics when fired at high temperature, while silicon carbide belongs to special ceramics, which is not as good as alumina ceramics in high temperature resistance but wear resistance.