Silicon Carbide Formula

Silicon carbide, more commonly referred to as carborundum, is a hard and strong non-oxide ceramic with unique physical properties that is frequently used in abrasives and metallurgical applications.

SiC is initially produced using the Acheson process; today it’s mass-produced using an electrical resistance brick furnace by mixing pure silica sand with finely ground coke, yielding yellow-green to blueish-black crystals with an iridescence that stands out.

Physical Properties

Silicon carbide (SiC) is an extremely hard, crystalline compound of silicon and carbon, known as Moissanite, first detected in its natural state (the Canyon Diablo meteorite in Arizona) by Nobel-prize winning chemist Henri Moissan in 1893 as part of his investigation of natural materials.

Silicon carbide has a layered crystal structure and comes in various polytypes with specific stacking arrangements of silicon and carbon atoms, known as an arrangement known as 3C-SiC; although there are over 100 other structures with similar chemical and physical properties.

Silicon carbide can be transformed into ceramic materials by sintering (binding the particles together by high temperatures) through various methods. One popular process for doing this is reaction bonded SiC, also known as Hexoloy(r), which uses reaction bonded sic powder mixed with porous carbon feedstock through additive forming, casting or extrusion to produce fully densified ceramic material with exceptional chemical and mechanical properties that perform at extreme end-use temperatures.

Chemical Properties

Silicon carbide has many beneficial properties that make it a valuable industrial compound. It is chemically inert and resistant to corrosion. Furthermore, silicon carbide makes an excellent abrasive that has become widely employed in modern lapidary due to its durability and Mohs hardness rating of 10.5.

This crystalline material can be doped to produce both n-type and p-type semiconductors, with nitrogen doping producing the former and gallium, aluminium or boron doping producing the latter. It has high temperature tolerance and does not react with alkalis or most organic substances with exception to hydrofluoric acid.

Silicon carbide’s extraordinary resilience has led it to be used in various applications, from ceramic brake discs for sports cars and bulletproof vests, to pump shaft seals due to its high thermal conductivity and ability to dissipate frictional heat before it transfers onto steel bearing surfaces. Furthermore, its complex chemical makeup means there are multiple forms or polytypes containing different crystal structures and bonding arrangements within its compound makeup.

Electrical Properties

Silicon carbide has garnered renewed recognition in recent years due to its exceptional mechanical properties like high hardness and chemical inertness, but it also boasts useful electrical characteristics. Due to its crystalline structure, silicon carbide allows impurities known as doping to be introduced through doping to create more free charge carriers such as electrons and holes within its material, increasing conductivity.

Silicon carbide’s unique atomic structure affords it relatively high thermal conductivity due to the tight packing of its atoms with large radii and their subsequent phononic conduction; this gives silicon carbide an edge over other structural ceramics such as aluminum nitride and beryllia which have lower thermal conductivities due to their wider atomic radii.

silicon carbide occurs naturally as the crystalline mineral moissanite in small amounts; however, most silicon carbide used commercially is produced synthetically for use as an abrasive or advanced refractories material by igniting mixture of silica sand and carbon in an electrical resistance furnace brick furnace.

Mechanical Properties

Silicon carbide (SiC) is an extremely hard ceramic material with a Mohs scale hardness of 9. It typically appears as yellow to green to bluish-black iridescent crystals that sublimate at 2700 degC before decomposing in water or with alkalis and iron at higher temperatures, boasting excellent corrosion resistance and strength at temperatures up to 1600 degC, with texture, grain size, stacking faults, impurities or stacking faults having secondary roles on mechanical properties.

Produced industrially through the Acheson process, which involves mixing silica with carbon in an electric furnace at high temperatures using Acheson method, or found naturally as moissanite first discovered at Canyon Diablo meteor crater in Arizona in 1893. Moissanite has long been recognized as an essential material in advanced functional ceramics, abrasives and metallurgical raw materials due to its excellent thermal conductivity and minimal thermal expansion as well as exceptional chemical stability; resistant to most organic and inorganic acids as well as salts but hydrofluoric acid or acid fluorides are present.

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