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All About Silicon Carbide

Silicon carbide (Sic), often known as carborundum, is the sole silicon-carbon compound. Moissanite, a mineral containing ,Sic does occur naturally, however it is extremely rare. It has, however, been mass manufactured as an abrasive in powder form since 1893. I

Formula for Silicon Carbide

Silicon carbide’s chemical formula is Sic, and its structure is

Silicon carbide is made up of tetrahedra of carbon and silicon atoms in a crystal lattice with strong bonding.

Its molar mass is40.10g/mol and its chemical formula is Sic. It’s a simple chemical with a triple bond connecting the carbon atom to the silicon atom, giving both atoms a positive and negative charge.

However, rather than being ionic, the bonding between them is largely covalent. Solid Sic is present commonly in crystalline hexagonal crystal structure.

Fully dense sintered Silicon Carbide is divided into two forms, both of which have fairly comparable qualities. Sintered Sic, such as Hexoloy or Ekasic, and reaction-bonded Sic, such as ‘Refel.

Characteristics of silicon carbide

Extremely hardness
Extremely strong
Low population density
Elastic modulus is high.
Thermal shock resistance is high.
Chemical inertness is superior.
Thermal conductivity is high.
Thermal expansion is minimal.

General information :

Up to 800°c silicon carbide is unaffected by acids, alkalis, or molten salts. Sic generates a protective silicon oxide coating in air at 1200°cand can withstand temperatures up to 1600°c.

This material has remarkable thermal shock resistance due to its strong thermal conductivity, minimal thermal expansion, and high strength.

Silicon carbide ceramics with few or no grain boundary imperfections may withstand temperatures of up to 1600°c without losing their strength.

Applications of silicon carbide:

Flexural strength: Flexural strength is described as a measurement of a beam’s ultimate strength in bending. When a substance is ductile, as most metals and alloys are, it bends before failing. If the material is brittle, such as ceramics or graphite, however, there will be a minor bending followed by a catastrophic failure. The four-point test and the three-point test are the two standard tests for determining the flexural strength of materials.

Power use: Silicon Carbide has a wide range of applications in several industries. Because of its physical hardness, it is good for abrasive machining techniques like grinding, honing, sandblasting, and water jet cutting.

Ceramic brake discs for sports cars are made from Silicon Carbide because of its ability to tolerate extremely high temperatures without breaking or warping.

It’s also utilised as an armour material in bulletproof vests and as a seal ring material for pump shaft sealing, where it’s regularly in touch with a silicon carbide seal. The excellent thermal conductivity of Silicon Carbide, which can dissipate the frictional heat created at a rubbing interface, is one of the key advantages in these applications.

Sublime material: One of the most remarkable aspects of silicon carbide is its ability to sublimate: at high enough temperatures, Sic bypasses the liquid state and transitions directly to a gaseous state. This means that instead of melting, it turns into a mist. Silicon carbide sublimation temperature (where this solid-to-vapour transition occurs) is roughly 2700°C (which is around half the surface temperature of the sun).

Semiconductor: Metallic conductivity can be achieved in a semiconductor material by substantial doping with nitrogen, aluminium, or boron. Gallium, aluminium, boron, or beryllium can be doped n-type with phosphorus or nitrogen, and p-type with gallium, aluminium, boron, or beryllium.

Electronics: Silicon carbide is an ideal semiconductor for power applications, because of its ability to sustain high voltages up to 10 times higher than those achievable with silicon. Silicon carbide semiconductors have a better thermal conductivity, higher electron mobility, and lower power losses than other semiconductors. Sic transistors and diodes can also function at greater frequencies and temperatures without sacrificing reliability.

Conclusion

High-temperature strength, good wear resistance, small thermal expansion coefficient, high hardness, thermal shock, chemical corrosion resistance, and so on are all advantages of silicon carbide ceramic materials. As a result, it is widely employed in the vehicle, mechanical, and chemical industries, as well as environmental protection, space technology, information electronics, and energy. Silicon carbide has evolved into an indispensable structural ceramic with outstanding performance in a variety of industries.