What is Silicon Carbide Definition Structure Preparation Reactions and Uses
Silicon carbide is also commonly said as Carborundum, which is a compound of both silicon and carbon. Silicon carbide can be described as a semiconductor material as an emerging material for the applications of semiconductor devices. Silicon carbide was discovered in 1891 by Pennsylvanian Edward Acheson. It is one of the essential industrial ceramic materials. It also plays a key role in the industrial revolution and is still used widely as a steel additive, abrasive and structural ceramic.
The IUPAC Name of Silicon Carbide is given as Methanidylidynesilanylium.
Properties of Silicon Carbide
Physical Properties of Silicon Carbide – SiC
Chemical Properties of Silicon Carbide – SiC
Silicon Carbide possesses interesting electrical properties because of its characteristics of semiconductors, the resistance of various compositions differing by as seven orders of magnitude.
Resistant to many organic and inorganic acids, salts, and alkalis in a variety of concentrations except to acid fluorides and hydrofluoric acid.
Silicon Carbide Structure – SiC
(Image to be added soon)
Natural Occurrence
Naturally-occurring moissanites are present only in small numbers in specific forms of meteorites and in kimberlite and corundum deposits. Virtually all the silicon carbide sold in the world is plastic, like moissanite jewellery. In 1893, natural moissanite was first found in Arizona as a small component of the Canyon Diablo meteorite by Dr Ferdinand Henri Moissan, after whom the material was named in 1905. The naturally occurring SiC discovered by Moissan was initially disputed due to his sample may have been contaminated by the silicon carbide saw blades that were already available on the market at that period.
While rare on the Earth, silicon carbide is defined remarkably as common in space. It is also a common form of stardust found around the carbon-rich stars, and the examples of this stardust have been found in pristine condition in unaltered (primitive) meteorites. The silicon carbide can also be found in space and meteorites are beta-polymorph, which is almost exclusively. The SiC grain analysis can be found in the Murchison meteorite, which is a carbonaceous chondrite meteorite and has revealed the anomalous isotopic ratios of silicon and carbon, indicating that these grains have originated outside the solar system.
Production
Because the natural moissanite is an extremely scarcest element, most of the silicon carbide is synthetic. Silicon carbide can be used as an abrasive and as a diamond simulant and semiconductor of gem-quality as well. The simplest process to manufacture the silicon carbide is to combine carbon and silica sand in electric resistance of an Acheson graphite furnace at a high temperature, raging from 1,600 °C (2,910 °F) and 2,500 °C (4,530 °F). The fine particles of SiO2 present in plant material (for example, rice husks) can be converted to SiC by heating the compound in the excess carbon from the organic material. The silica fume, a byproduct of producing ferrosilicon alloys and silicon metal, can also be converted to SiC by heating with graphite at a temperature of 1,500 °C (2,730 °F).
The material, which is formed in the Acheson furnace differs in purity, as per its distance from the graphite resistor heat source. Colourless, green, and pale yellow crystals have the highest purity and can be found closest to the resistor. The colour changes to black and blue at a greater distance from the resistor and these darker crystals are less pure. Aluminium and Nitrogen are the common impurities, and they affect the SiC's electrical conductivity.
Uses of Silicon Carbide
Abrasive and Cutting Tools
Silicon carbide is a popular abrasive in the arts in modern lapidary because of the low cost and durability of the material. Also, in the process of manufacturing, it is used for its hardness in the abrasive machining processes including honing, grinding, sandblasting, and water-jet cutting. Silicon carbide particles are laminated to paper to create grip tape on skateboards and sandpapers.
Automobile Parts
The carbon-carbon composite of Silicon-infiltrated is used for high performance "ceramic" brake disks since they can withstand extreme temperatures. Silicon also reacts with the graphite in the composite of carbon-carbon to form carbon-fibre-reinforced silicon carbide (C/SiC). These brake disks can be used on a few supercars, road-going sports cars, and other performance cars as well, including the Bugatti Veyron, Porsche Carrera GT, the McLaren P1, Ferrari, Bentley, Lamborghini, and a few Audi cars, which have a specific high-performance. Silicon carbide can also be used in a sintered form for diesel particulate filters. It is also used as an oil additive to reduce emissions, harmonics, and friction.
Foundry Crucibles
Silicon Carbide is used in crucibles for holding the melting metal in the applications of both small and large foundry.
FAQs on Silicon Carbide Structure Properties Preparation and Applications
1. What is silicon carbide?
Silicon carbide is a covalent compound composed of silicon and carbon with the chemical formula SiC.
- It consists of a network of strong Si–C covalent bonds.
- It forms a giant covalent (network) lattice similar to diamond.
- It is also known as carborundum in industrial applications.
- Silicon carbide is widely used as an abrasive and semiconductor material.
2. What is the chemical formula of silicon carbide?
The chemical formula of silicon carbide is SiC.
- It contains one silicon (Si) atom bonded to one carbon (C) atom.
- The compound forms a repeating 3D covalent network rather than discrete molecules.
- Its empirical and molecular formulas are the same: SiC.
3. How is silicon carbide made?
Silicon carbide is produced industrially by heating silica and carbon at high temperatures in the Acheson process.
- Raw materials: SiO2(s) (silica) and C(s) (coke).
- Balanced reaction: SiO2(s) + 3C(s) → SiC(s) + 2CO(g)
- Temperature required: about 2000–2500°C in an electric furnace.
- Carbon monoxide gas is released as a by-product.
4. Is silicon carbide ionic or covalent?
Silicon carbide is a covalent network solid, not an ionic compound.
- It has strong directional Si–C covalent bonds.
- The small electronegativity difference between Si and C prevents full electron transfer.
- Its structure is similar to diamond, giving it extreme hardness.
5. Why is silicon carbide so hard?
Silicon carbide is extremely hard because it has a giant covalent lattice with strong Si–C bonds throughout the structure.
- Each atom is tetrahedrally bonded to four others.
- Breaking the solid requires breaking many strong covalent bonds.
- Its hardness is close to that of diamond on the Mohs scale.
6. What are the main properties of silicon carbide?
Silicon carbide has high hardness, high thermal stability, and semiconductor properties.
- High melting point (above 2700°C, decomposes before melting at normal pressure).
- High thermal conductivity.
- Chemically inert and resistant to oxidation at moderate temperatures.
- Acts as a wide band gap semiconductor.
7. What is silicon carbide used for?
Silicon carbide is used as an abrasive, refractory material, and semiconductor.
- Manufacture of grinding wheels and sandpaper (abrasive use).
- High-temperature furnace linings (refractory material).
- Power electronics such as SiC diodes and MOSFETs.
- LED technology and high-voltage devices.
8. Is silicon carbide a semiconductor?
Yes, silicon carbide is a wide band gap semiconductor used in high-power and high-temperature electronics.
- It has a larger band gap (~3.0 eV) than silicon (~1.1 eV).
- It operates at higher voltages and temperatures than elemental silicon.
- It is commonly used in power converters and electric vehicles.
9. What is the structure of silicon carbide?
Silicon carbide has a tetrahedral covalent network structure similar to diamond.
- Each silicon atom bonds to four carbon atoms.
- Each carbon atom bonds to four silicon atoms.
- It exists in different crystalline forms called polytypes (e.g., 3C, 4H, 6H).
10. How does silicon carbide react with oxygen?
Silicon carbide reacts with oxygen at high temperatures to form silicon dioxide and carbon dioxide.
- Balanced reaction: SiC(s) + 2O2(g) → SiO2(s) + CO2(g)
- A protective SiO2 layer forms on the surface.
- This oxide layer improves oxidation resistance at moderate temperatures.
