Boron carbide
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2008-07-10T20:22:20Z
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{{expert-subject|Physics}}
{{Chembox new
| Name = Boron carbide
| ImageFile =
| ImageSize =
| ImageName = Boron carbide
| IUPACName = Boron carbide
| OtherNames = Tetrabor<br />B4-C<br />B4C<br />Black Diamond
| Section1 = {{Chembox Identifiers
| CASNo = 12069-32-8
}}
| Section2 = {{Chembox Properties
| Formula = B<sub>4</sub>C
| MolarMass = 55.255 g/mol
| Appearance = Black powder.
| Density = 2.52 g/cm<sup>3</sup>, solid.
| Solubility = Insoluble.
| MeltingPt = 2350 °C (2623.15 K)
| BoilingPt = >3500 °C (>3773.15 K)
}}
| Section3 = {{Chembox Structure
| MolShape =
| Coordination =
| CrystalStruct = [[Rhombohedral]]
| Dipole =
}}
| Section7 = {{Chembox Hazards
| ExternalMSDS = [http://www.logitech.uk.com/MSDS/Files%5C0CON-024%20to%20028.pdf External MSDS]
| MainHazards = Harmful, irritant.
}}
| Section8 = {{Chembox Related
| OtherAnions =
| OtherCations =
| OtherCpds = [[Boron nitride]]
}}
}}
'''Boron carbide''' (chemical formula B<sub>4</sub>C) is an extremely hard [[ceramic]] material used in [[tank]] [[armor]], [[bulletproof vest]]s, and numerous industrial applications. With a hardness of 9.3 on the [[mohs scale]], it is the fifth hardest material known behind [[boron nitride]], [[diamond]], [[ultrahard fullerite]], and [[aggregated diamond nanorods]].
Discovered in the 19th century as a by-product of reactions involving metal borides, it was not until the 1930s that the material was studied scientifically. Boron carbide is now produced industrially by the carbo-thermal reduction of B<sub>2</sub>O<sub>3</sub> ([[boron oxide]]) in an electric [[arc furnace]].
Its ability to absorb neutrons without forming long lived [[radionuclide]]s makes the material attractive as an absorbent for neutron radiation arising in nuclear power plants. Nuclear applications of boron carbide include shielding, control rod and shut down pellets. Within control rods, boron carbide is often powdered, to increase its surface area.
==References==
* Carbide, Nitride and Boride Materials Synthesis and Processing ISBN 0-412-54060-6
==External links==
* [http://www.npi.gov.au/database/substance-info/profiles/15.html National Pollutant Inventory - Boron and compounds]
* [http://webbook.nist.gov/cgi/cbook.cgi?ID=C12069328&Units=SI&Mask=2#Thermo-Condensed NIST Chemistry Database Entry for Boron Carbide]
[[Category:Carbides]]
[[Category:Boron compounds]]
[[Category:Superhard materials]]
[[Category:Neutron poisons]]
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[[ru:Карбид бора]]
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[[zh:碳化硼]]