Формула карбида кремния

Silicon carbide (also referred to as silicon carbonitride or SiC) is a green to bluish black crystalline compound composed of silicon and carbon found naturally as moissanite gem but since 1891 has also been produced synthetically for use as an abrasive in grinding wheels and cutting tools.

Quartz is an extremely hard material with a Mohs scale rating of 9. It comes in many polymorphs and can be doped with nitrogen, boron and aluminium for use as semiconductor material.

Physical

Silicon carbide (SiC) is an extremely hard and durable synthetically manufactured crystalline compound of silicon and carbon, used widely in applications ranging from sandpaper and grinding wheels, industrial furnace linings, wear-resistant parts for machinery wear-resistance applications, high temperature ceramics production, semiconducting substrates for light emitting diodes (LED), semi-conductors substrates as well as semiconducting substrates in semi-conductors (LC). Notable physical characteristics include its extreme hardness and thermal conductivity.

Chemical compounds consist of many distinct crystalline structures known as polytypes that share similar layers but vary in terms of stacking sequence. Each polytype has its own crystal structure and distinct physical properties.

Pure silicon carbide is generally an insulator in its native state; however, when doped with agents such as nitrogen, phosphorus, or beryllium it can show semi-conductivity properties and allow current to pass through it without being blocked by obstruction.

SiC’s most frequently encountered form is alpha silicon carbide (a-SiC), with its hexagonal close-packed crystal structure comprising half-filled tetrahedra. This form of SiC is ideal for producing sandpaper and grinding wheels using Lely process technology.

Beta silicon carbide with its zinc blende crystal structure is one of the two primary polymorphs of SiC. This form can be found both in space as stardust from carbon-rich stars, and on meteorites such as Canyon Diablo specimen. Furthermore, this compound is found as an ingredient in certain industrial chemicals; some workers who have been exposed have even developed pneumoconiosis due to beta SiC exposure.

Chemical

Silicon carbide (SiC) is an extremely hard (9 on the Mohs scale), crystalline chemical compound of silicon and carbon. When produced as pure powder it has semiconductor properties and appears colorless; industrial production yields brown to black iridescent grains or powder. Also referred to as carborundum it occurs naturally as moissanite in nature as well as being artificially produced since 1891 for use in abrasives, metallurgical, and refractory applications.

SiC is typically manufactured industrially using two processes. One involves adding small amounts of carbon or boron to the raw material to improve densification and reduce porosity; powder is then compressed together before being sintered in an electrically heated furnace to form compacts or granules with desired sizes, shapes, densities, chemical composition and densities.

Material such as this is highly abrasive, posing serious damage to equipment. Therefore, proper precautions must be taken when handling this substance – including using respiratory masks and gloves along with adhering to all applicable safety regulations and guidelines. Inhalation poses an immediate respiratory hazard which may also cause skin or eye irritation and digestive upset; so for optimal storage conditions away from food and liquid sources should occur in a well-ventilated space.

Mechanical

Silicon carbide boasts of outstanding refractory ceramic properties that give it high hardness, stiffness and tensile strength as well as chemical and thermal shock resistance, making it an excellent abrasive material in many applications such as grinding wheels, cutting tools or sand blasting materials. Furthermore, silicon carbide reinforcement is often utilized in hard ceramics such as porcelain as well as glasses stones and metallic linings to reinforce them against wear-and-tear conditions.

Moissanite can be found naturally as the rare mineral moissanite; however, since 1893 commercial production for use as an abrasive has taken place using the Acheson process. The mixture created when mixing pure silica (SiO2) quartz sand with finely ground petroleum coke combined with carbon electrode in an electric furnace forms small crystals of silicon carbide that can then be ground into powder for use as an abrasive.

Silicon carbide exists in various polytypes that differ in their crystal structures and stacking sequences. One form, alpha silicon carbide (SiC), features hexagonal crystal structure while beta modification with zinc blende structure similar to diamond is less popular yet may have useful properties.

This material is generally an ineffective conductor of electricity; however, its semiconductivity can be expressed through doping with certain impurities or applying external fields. Thus, it finds widespread application in electronic devices, such as transistors and diodes where semi-conducting materials are required.

Electrical

Silicon carbide’s electrical properties can be traced back to its multilayer crystal structure. As such, silicon carbide forms many polytypes with variations only in their stacking sequence of otherwise identical bilayers; therefore it is considered wide band-gap material since electronic energy levels vary considerably among the polytypes as opposed to narrower bands in silicon (the parent element).

Silicon carbide powders are most frequently utilized by bonding them together with various binders under high temperature and pressure to form ceramics or solids, such as those found in wear-resistant parts for cars or machinery. Since the late 19th century, silicon carbide has been utilized both abrasively and metallurgically; for refractory linings in furnaces or grinding wheels; wear resistant parts; as well as electronic applications like light emitting diodes and detectors used in early radios.

SiC in its pure state is an insulator; however, by doping it with impurities such as aluminum, boron and gallium dopants or nitrogen or phosphorus dopants can become either P-type or N-type semiconductors.

SiC has outstanding thermal expansion properties, with an exceptional low thermal expansion coefficient. Its strength allows it to withstand temperatures as high as 1600degC without suffering significant degradation of integrity or integrity loss, and also has excellent corrosion and oxidation resistance in air, water and many solvents.