Chromium(II) carbide

Chromium carbide[1]
Names
IUPAC name
Chromium(II) carbide
Other names
Chromium carbide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.031.420 Edit this at Wikidata
  • InChI=1S/2C.3Cr checkY
    Key: UFGZSIPAQKLCGR-UHFFFAOYSA-N checkY
  • InChI=1/2C.3Cr/rC2Cr3/c3-1-5-2-4
    Key: UFGZSIPAQKLCGR-HMFAXLTNAU
  • [Cr]#C[Cr]C#[Cr]
Properties
Cr3C2
Molar mass 180.009 g/mol
Appearance gray orthorhombic crystals
Density 6.68 g/cm3
Melting point 1,895 °C (3,443 °F; 2,168 K)
Boiling point 3,800 °C (6,870 °F; 4,070 K)
reacts
Structure
Orthorhombic, oP20
Pnma, No. 62
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g. diesel fuelInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
1
2
1
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 1 mg/m3[2]
REL (Recommended)
 TWA 0.5 mg/m3[2]
IDLH (Immediate danger)
 250 mg/m3[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Chromium(II) carbide is a ceramic compound that exists in several chemical compositions: Cr3C2, Cr7C3, and Cr23C6. At standard conditions it exists as a gray solid. It is extremely hard and corrosion resistant. It is also a refractory compound, which means that it retains its strength at high temperatures as well. These properties make it useful as an additive to metal alloys. When chromium carbide crystals are integrated into the surface of a metal it improves the wear resistance and corrosion resistance of the metal, and maintains these properties at elevated temperatures. The hardest and most commonly used composition for this purpose is Cr3C2.

The mineral form of the Cr3C2 compound is tongbaite.[3] Isovite, (Cr,Fe)
23C
6, is a related mineral. Both are extremely rare.[4] Yet another chromium-rich carbide mineral is yarlongite, Cr4Fe4NiC4.[5]

  1. ^ Lide, David R. (1998), Handbook of Chemistry and Physics (87 ed.), Boca Raton, Florida: CRC Press, pp. 4–52, ISBN 0-8493-0594-2
  2. ^ a b c NIOSH Pocket Guide to Chemical Hazards. "#0141". National Institute for Occupational Safety and Health (NIOSH).
  3. ^ Tongbaite: Mineral information, data and localities, Mindat.org
  4. ^ Generalov ME, Naumov VA, Mokhov AV, Trubkin NV, "Isovite (Cr,Fe)23C6 - a new mineral from the gold-platinum bearing placers of the Urals", Zapiski Vserossiyskogo mineralogicheskogo obshchestva, vol. 127, pp.26-37, 1998.
  5. ^ Mindat, http://www.mindat.org/min-35899.html