Chromium carbide
3163517
202775049
2008-04-02T10:57:59Z
OKBot
4559949
robot Adding: [[ar:كربيد كروم]]
{{Chembox new
| Name = Chromium carbide
| ImageFile = Chromium carbide.jpg
<!-- | ImageSize = 200px -->
| ImageName = Chromium carbide
| OtherNames =
| Section1 = {{Chembox Identifiers
| CASNo = 12012-61-9
}}
| Section2 = {{Chembox Properties
| Formula = Cr<sub>3</sub>C<sub>2</sub>
| MolarMass = 180.01 g/mol
| Density = 6.65-6.68 g/cm³
| MeltingPt = 1890 °C
| BoilingPt = }}
}}
'''Chromium carbide''' ([[Chromium|Cr]]<sub>3</sub>[[Carbon|C]]<sub>2</sub>) is an extremely [[hardness|hard]] [[refraction (metallurgy)|refractory]] [[ceramic]] material. It is usually processed by [[sintering]]. It has the appearance of a gray powder with [[orthorhombic]] [[crystal structure]]. Its [[CAS number]] is 12012-61-9.
Other compositions are available, eg. Cr<sub>23</sub>C<sub>6</sub>, and Cr<sub>7</sub>C<sub>3</sub>.
Chromium carbide is used as a thermal spray material for protecting the underlying metal surface, and as an additive to corrosion-resistant and wear-resistant materials. It is used in coatings of [[bearing (mechanical)|bearings]], seals, orifices, and valve seals, and as a fine-crystal phase in other sintered carbides, where, like the [[vanadium carbide]], it inhibits growth of submicrometre grains during pressing and sintering. It is highly [[corrosion]]-resistant, and does not oxidize even at high temperature (1000-1100 °C). The powder for coating costs $40-$65 per pound.
The [[thermal expansion]] coefficient of chromium carbide is almost equal to that of [[steel]], reducing the mechanical stress buildup at the layer boundary.
Precipitation of chromium carbide at the grain boundaries, depleting the grain edges of chromium, is the cause of [[intergranular corrosion]] of [[stainless steel]] near the [[weld]]s.
Physical Properties:
* [[Density]] ( kg/m³ ): 6,650-6,680 (Cr<sub>3</sub>C<sub>2</sub>)
* [[Melting point]] ( °C ): 1250 (Cr<sub>23</sub>C<sub>6</sub>), 1665 (Cr<sub>7</sub>C<sub>3</sub>), 1890 (Cr<sub>3</sub>C<sub>2</sub>).
==References==
{{Unreferenced|date =September 2007}}
<references/>
==External links==
* [http://www.npi.gov.au/database/substance-info/profiles/24.html National Pollutant Inventory - Chromium (III) compounds fact sheet]
[[Category:Carbides]]
[[Category:Chromium compounds]]
[[Category:Superhard materials]]
[[Category:Refractory materials]]
{{inorganic-compound-stub}}
[[ar:كربيد كروم]]