What Is Silicon Carbide Used For?

Silicon carbide, more commonly referred to as carborundum, is a synthetically produced, extremely hard, crystalline compound of silicon and carbon that serves multiple industrial purposes including being an abrasive, refractory material and semiconductor material.

SiC is typically produced as a cylindrical ingot with layers of alpha grade material (a coarse crystal structure), beta grade material and other grades as well as unreacted material on its exterior surface.

Abrasive

Silicon carbide, often referred to as black silicon carbide (a-SiC), has long been utilized as a hard and tough material with multiple applications in various abrasive industries and composite materials for bulletproof vests.

Silicon carbide abrasive materials are widely utilized in industrial processes like grinding, honing, water-jet cutting and abrasive blasting – the latter using high-pressure machinery to propel ceramic powder through high-velocity streams across hard surfaces to remove rust or strip away old coatings and paint layers.

Other applications for abrasives include construction industry applications like cement and asphalt; aerospace/automotive use of ceramic include making brakes that withstand high temperatures/stress; as well as being embedded into bulletproof vests for bulletproof protection.

Manufacturing of abrasive silicon carbide begins by mixing silica sand with petroleum coke in an adhesion graphite resistance furnace and heating to very high temperatures, then crushed, washed with acid and alkali solutions, magnetically separated, sieved to produce different particle sizes, then sintered using various methods such as hot pressing, microwave sintering or pressure-less sintering.

Refractory

Silicon carbide is a high-strength and durable refractory ceramic used in various industrial applications. It can withstand high temperatures, thermal shock and chemical resistance; furthermore it is highly abrasive making it perfect for grinding and polishing applications. Silicon carbide has found particular use in electronics production where lapping films made with it are used to polish fiber-optic strand ends prior to splicing – providing crucial assurance of proper functioning splices.

Refractory silicon carbide comes in various grades to meet different applications and requirements. Green refractory silicon carbide has relatively stable chemical properties and is produced by refining quartz sand with petroleum coke in a resistance furnace, while black refractory silicon carbide is produced by firing pure SiC mixed with additives in an elevated nitrogen environment at elevated temperatures, creating both nitride-bonded and reaction-bonded phases: a-SiC and b-SiC respectively; the latter having superior mechanical strength over its counterpart.

Refractory silicon carbide can be easily formed and cast into blocks for use in industrial processes like steelmaking, ceramics production, glassmaking and power generation. Thanks to its resistance to extreme temperatures, thermal shock, harsh chemical environments and corrosion-inhibition properties it makes an invaluable part of manufacturing process. Furthermore, waste-to-energy facilities that convert domestic waste into energy sustainable solutions may find refractory silicon carbide an ideal choice as a waste converter material.

Heat Resistant

Silicon is susceptible to melting under high temperatures; whereas, silicon carbide power devices remain reliable even under extremely high voltage environments – which makes them an excellent choice for power electronics devices such as smart appliances, servers and renewable energies such as electric vehicles, wind power or photovoltaic solar panels.

Silicon carbide’s heat resistance has made it an invaluable material for making refractory materials such as kiln furniture, hearth plates, recuperator tubes and pusher slabs. Its crystalline structure and high melting point are ideal for creating long-lasting and highly durable refractory products.

Silicon carbide’s unique properties of being heat and corrosion-resistant make it an excellent material to use for manufacturing ceramics, as well as refractory applications such as metal casting and smelting furnaces.

Silicon carbide’s heat resistance also makes it an ideal raw material for producing carbon-fiber reinforced silica — used to manufacture high performance “ceramic” brake discs found on many sports and exotic cars. Studies have revealed this material’s ability to reduce friction, improving fuel economy and performance while protecting against potential damage to extend disc life span.

Semiconductor

Silicon carbide’s bandgap is three times wider than standard silicon semiconductors, making it an excellent material choice for electrical applications. The wider gap enables electrons to jump across from valence bands into conduction bands easily, creating current flow. SiC’s performance advantage makes it the go-to material in high voltage applications such as electric vehicles and solar power inverters.

Silicon carbide is best known for its heat endurance and resistance to abrasion; one of its other main properties is hardness, ranking ninth on Mohs scale mineral hardness scale between alumina at 10 and diamond at 12. This hardness is caused by its crystal lattice holding together tetrahedral structures formed of silicon-carbon bonds arranged tetrahedra that help provide its hardness.

Silicon carbide’s unique physical and chemical properties make it an ideal material for a wide range of industrial uses, from abrasive machining such as sandblasting and grinding to producing smooth surfaces necessary for fiber optic splices to function correctly.

Silicon carbide production for use in abrasives, metallurgical, and refractories industries involves building up a mixture of pure silica sand with coal (usually coke) in an electrical resistance-type furnace, then passing power through this conductor causing chemical reaction that converts coke to silicon carbide and carbon monoxide gas production. This process typically lasts several days while reaching temperatures as high as 2,200-2,700deg Celsius at its core and about 1,400deg Celsius around its edges.