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]]