Silicon carbide

Processes

Silicon carbide (SiC) is essentially a synthetic material. It was discovered by Johan Berzélius in 1824 through a parasite reaction between carbon and silica during diamond synthesis at high temperature. It is now mainly formed by reaction at heat (> 2,500°C) between silicon and carbon or by reduction of silica through excess carbon.

Silicon carbide can be used in powder form, fibre, deposit or as a solid material. It is sintered at a very high temperature (> 2,000°C) in a neutral or reducing atmosphere to prevent oxidation problems.

Properties

SiC has a low density (3.2 g/cm3) and is mainly used for its hardness comparable to that of diamond (9-10 Mohs) and its chemical inertia at high temperature. It also has high thermal and electrical conductivity and low thermal expansion.

Applications

Silicon carbide is mainly used in machining (cutting tool, sliding block) or as an abrasive (mechanical seals, ceramic matrix composite). It can also be used as a heat exchanger, a carrier support or for its wide bandgap (3 eV) semiconductor properties for applications in power electronics. It is also used in the spatial sector as a large reflector system and telescope structure (Herschel, Gaïa).

Raw material
Finished product

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