• Italian: carburo
• Spanish: carburo

• Italian: carburo di tungsteno
• Spanish: carburo de tungsteno

• Italian: carburo di calcio
• Spanish: carburo de calcio

See also

• cementite

For the software development tool targeting the Symbian OS, see Carbide.c++.

In chemistry, a carbide is a compound of carbon with a less electronegative element. Carbides are important industrially: for example, calcium carbide is a feedstock for the chemical industry and iron carbide, Fe3C (cementite), is formed in steels to improve their properties.

Many carbides can be generally classified by chemical bonding type as follows:

• salt-like ionic compounds
• covalent compounds
• interstitial compounds
• "intermediate" transition metal carbides (a group of carbides that in bonding terms sit between the salt-like and interstitial carbides).

In addition to the carbides there are other groups of binary carbon compounds, i.e. Mg2C3 yields methylacetylene, CH3CCH, on hydrolysis which was the first indication that it may contain C34−.

Covalent carbides

Silicon and boron form covalent carbides.

Structure

The longheld view is that the carbon atoms fit into octahedral interstices in a close packed metal lattice when the metal atom radius is greater than approximately 135 pm:.

Intermediate transition metal carbides

In these the transition metal ion is smaller than the critical 135 pm and the structures are not interstitial but are more complex. Multiple stoichiometries are common, for example iron forms a number of carbides, Fe3C, Fe7C3 and Fe2C. The best known is cementite, Fe3C, which is present in steels. These carbides are more reactive than the interstitial carbides, for example the carbides of Cr, Mn, Fe, Co and Ni all are hydrolysed by dilute acids and sometimes by water, to give a mixture of hydrogen and hydrocarbons. These compounds share features with both the inert interstitals and the more reactive salt-like carbides.

References