Difference between revisions of "Carbide" - New World Encyclopedia

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Calcium carbide

In chemistry, a carbide is a compound of carbon with a less electronegative element.^[1] Many carbides are important industrially; for example, calcium carbide (CaC₂) is a feedstock for the chemical industry and iron carbide (Fe₃C, cementite) is formed in steels to improve their properties.

In general, carbides are classified according to the chemical bonding in the compounds, as follows:

salt-like ionic carbides;
covalent carbides;
interstitial carbides;
"intermediate" transition metal carbides. (In bonding terms, they sit between the salt-like and interstitial carbides.)

Ionic carbides

Salt-like, ionic carbides are formed by the following metals:

group one metals (the alkali metals);
group two metals (the alkaline earths);
group three metals (scandium, yttrium, and lanthanum);
group 11 metals (copper, silver, and gold);
group 12 metals (zinc, cadmium, and mercury);
only aluminum from group 13, (gallium, indium and thallium do not appear to form carbides);
lanthanides, when forming MC₂ and M₂C₃ carbides (where M is the metal);
actinides, when forming MC₂ and M₂C₃ carbides.

Most commonly, they are salts of C₂²⁻ and are called acetylides, ethynides, acetylenediides, or (rarely) percarbides.
Some ionic carbides contain other anionic species, such as:

C⁴⁻, sometimes called methanides (or methides) because they hydrolyze to give methane gas;
C₃⁴⁻ ion, sometimes called sesquicarbides, which hydrolyze to give methylacetylene.

The naming of ionic carbides is not consistent and can be quite confusing.

Acetylides

Acetylides contain the polyatomic ion C₂²⁻, in which there is a triple bond between the two carbon atoms (similar to acetylene). Examples are carbides of the alkali metals (such as Na₂C₂), some alkaline earths (such as CaC₂) and lanthanoids (such as LaC₂).

The C-C bond distance ranges from 109.2 picometers (pm) in CaC₂ (similar to acetylene), to 130.3 pm in LaC₂ and 134pm in UC₂.

Methanides

Methanides contain the monatomic ion C⁴⁻. Examples of methanides are Be₂C and Al₄C₃.

The C⁴⁻ ion is a very strong base and will combine with four protons to form methane. The reaction may be written as follows:

C⁴⁻ + 4H⁺ → CH₄

Methanides commonly react with water to form methane, but reactions with other substances are also common.

Sesquicarbides

The polyatomic ion C₃⁴⁻ is found in, for instance, Li₄C₃ and Mg₂C₃. The ion is linear and isoelectronic with CO₂. The C-C distance in Mg₂C₃ is 133.2 pm.^[2] Hydrolysis of Mg₂C₃ yields methylacetylene (CH₃CCH), which was the first indication that it may contain C₃⁴⁻.

Covalent carbides

Silicon and boron form covalent carbides. Silicon carbide (SiC, or carborundum) has two similar crystalline forms, both of which are related to the structure of diamond. Boron carbide (B₄C), on the other hand, has an unusual structure, which includes icosahedral boron units linked by carbon atoms. In this respect, boron carbide is similar to the boron-rich borides. Both silicon carbide and boron carbide are very hard, refractory (heat-resistant) materials. Both are important industrially. Boron also forms other covalent carbides, such as B₂₅C.

Interstitial carbides

Properties

The carbides of transition metals of groups four, five, and six (with the exception of chromium) are often described as interstitial compounds. They are chemically quite inert, have metallic properties, and are refractory. Some exhibit a range of stoichiometries (that is, the metal and carbon atoms can be combined in different proportions). Titanium carbide and tungsten carbide are important industrially and are used to coat metals in cutting tools.

Structure

The carbon atoms are thought to fit into octahedral interstices in the metal lattice, when the metal atom radius is greater than 135 pm. If the metal atoms are cubic close packed (face-centered cubic), then eventually all the interstices could be filled to give a 1:1 stoichiometry, with the rock salt structure, as in the case of tungsten carbide (WC). When the metal atoms are hexagonal close packed, then only half the interstices are filled, giving a stoichiometry of 2:1, as in the case of divanadium carbide (V₂C).

The following table shows actual structures of metals and their carbides. The notation "h/2" refers to the V₂C-type structure mentioned above, which is an approximate description of the actual structures. The simple view that the lattice of the pure metal "absorbs" carbon atoms is true only for the monocarbides of vanadium (VC) and niobium (NbC).

Metal	Structure	Metallic radius (pm)	MC structure	M₂C structure	Other carbides
titanium	hexagonal	147	rock salt
zirconium	hexagonal	160	rock salt
hafnium	hexagonal	159	rock salt
vanadium	cubic body centered	134	rock salt	h/2	V₄C₃
niobium	cubic body centered	146	rock salt	h/2	Nb₄C₃
tantalum	cubic body centered	146	rock salt	h/2	Ta₄C₃
chromium	cubic body centered	128			Cr₂₃C₆, Cr₃C, Cr₇C₃, Cr₃C₂
molybdenum	cubic body centered	139	hexagonal	h/2	Mo₃C₂
tungsten	cubic body centered	139	hexagonal	h/2

For a long time, the non-stoichiometric phases were believed to be disordered, with a random filling of the interstices. However, short and longer range ordering has been detected.^[3]

Intermediate transition metal carbides

In these carbides, 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 of these 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 are all hydrolyzed by dilute acids and sometimes by water, to give a mixture of hydrogen and hydrocarbons. These compounds share features with both the inert interstitials and the more reactive, salt-like carbides.

Some carbides and their uses

Calcium carbide (CaC₂): It is used for the production of acetylene and calcium cyanamide (CaCN₂), which is used in fertilizers. It is also important for the desulfurization of iron.
Silicon carbide (SiC), or carborundum: It is used as an abrasive and in ceramics.
Tungsten carbide (often called simply carbide): Being extremely hard, it is useful for the manufacture of cutting tools, abrasives, and bearings.
Cementite (iron carbide; Fe₃C): It is an important constituent of steel.
Boron carbide: It is used in cutting tools, dies, and anti-ballistic armor plating. It is an effective absorbent of neutron radiation in nuclear power plants.
Tantalum carbide: It is an extremely hard, refractory, ceramic material, used in tool bits for cutting tools.
Titanium carbide: Similar to tantalum carbide, it is an extremely hard, refractory, ceramic material.

Notes

↑ Some binary carbon compounds are not called carbides. They include: (a) graphite intercalation compounds; (b) alkali metal fullerides; (c) endohedral fullerenes, where the metal atom is encapsulated within a fullerene molecule; and (d) metallacarbohedrenes (met-cars), which are cluster compounds containing C₂ units.
↑ Fjellvag H. and Pavel K. Crystal Structure of Magnesium Sesquicarbide. Chem. 1992, 31, 3260.
↑ de Novion, C.H., and J.P. Landesman. 1985. "Order and disorder in transition metal carbides and nitrides: experimental and theoretical aspects," Pure & Appl. Chem. 57 (10): 1391.

References
ISBN links support NWE through referral fees

Brown Jr., Theodore L., H. Eugene LeMay, Bruce Edward Bursten, and Julia R. Burdge. 2002. Chemistry: The Central Science. 9th ed. Upper Saddle River, NJ: Prentice Hall.
Chang, Raymond. 2006. Chemistry. 9th ed. New York, NY: McGraw-Hill Science/Engineering/Math.
Cotton, F. Albert, and Geoffrey Wilkinson. 1980. Advanced Inorganic Chemistry. 4th ed. New York, NY: Wiley. ISBN 0-471-02775-8.
Ettmayer, Peter, and Walter Lengauer. 1994. Carbides: transition metal solid state chemistry. In Encyclopedia of Inorganic Chemistry. Editor in chief R. Bruce King. Chichester, UK: Wiley. ISBN 0-471-93620-0.
Greenwood, N.N., and A. Earnshaw. 1998. Chemistry of the Elements. 2nd ed. Oxford, U.K.; Burlington, MA: Butterworth-Heinemann, Elsevier Science. ISBN 0750633654. Online version available here Retrieved January 4, 2008.

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[1] Some binary carbon compounds are not called carbides. They include: (a) graphite intercalation compounds; (b) alkali metal fullerides; (c) endohedral fullerenes, where the metal atom is encapsulated within a fullerene molecule; and (d) metallacarbohedrenes (met-cars), which are cluster compounds containing C₂ units.

[2] Fjellvag H. and Pavel K. Crystal Structure of Magnesium Sesquicarbide. Chem. 1992, 31, 3260.

[3] Novion, C.H., and J.P. Landesman. 1985. "Order and disorder in transition metal carbides and nitrides: experimental and theoretical aspects," Pure & Appl. Chem. 57 (10): 1391.

[1]

[2]

[3]

@@ Line 1: / Line 1: @@
-{{Claimed}}
+{{Copyedited}}{{Images OK}}{{Submitted}}{{Approved}}{{Paid}}
-[[Image:Carbid.jpg|200px|thumb|Calcium carbide.]]
+[[Image:Carbid.jpg|200px|thumb|Calcium carbide]]
+In [[chemistry]], a '''carbide''' is a compound of [[carbon]] with a less [[electronegativity|electronegative]] element.<ref>Some binary carbon compounds are not called carbides. They include: (a) [[graphite intercalation compound]]s; (b) alkali metal fullerides; (c) [[endohedral fullerenes]], where the metal atom is encapsulated within a fullerene molecule; and (d) metallacarbohedrenes (met-cars), which are cluster compounds containing C<sub>2</sub> units.</ref> Many carbides are important industrially; for example, [[calcium carbide]] (CaC<sub>2</sub>) is a feedstock for the chemical industry and iron carbide (Fe<sub>3</sub>C, [[cementite]]) is formed in steels to improve their properties.
-In [[chemistry]], '''Carbide''' is a compound of [[carbon]] with a less [[electronegativity|electronegative]] element. Carbides are important industrially; for example [[calcium carbide]] is a feedstock for the chemical industry and iron carbide, Fe<sub>3</sub>C ([[cementite]]), is formed in steels to improve their properties.
+In general, carbides are classified according to the chemical bonding in the compounds, as follows:
-<br />
+* salt-like ionic carbides;
-Many carbides can be generally classified by chemical bonding type as follows:
+* covalent carbides;
+* interstitial carbides;
+* "intermediate" transition metal carbides. (In bonding terms, they sit between the salt-like and interstitial carbides.)
-* salt-like ionic compounds
+==Ionic carbides==
-* 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.
-*[[graphite intercalation compound]]s
-*alkali metal fullerides
-*[[endohedral fullerenes]], where the metal atom is encapsulated inside a fullerene molecule
-*metallacarbohedrenes(met-cars) which are cluster compounds containing C<sub>2</sub> units.
-==Examples==
+Salt-like, ionic carbides are formed by the following metals:
+*group one metals (the [[alkali metal]]s);
+*group two metals (the [[alkaline earth]]s);
+*group three metals ([[scandium]], [[yttrium]], and [[lanthanum]]);
+*group 11 metals ([[copper]], [[silver]], and [[gold]]);
+*group 12 metals ([[zinc]], [[cadmium]], and [[mercury (element)|mercury]]);
+*only [[aluminum]] from group 13, ([[gallium]], [[indium]] and [[thallium]] do not appear to form carbides);
+*[[lanthanide]]s, when forming MC<sub>2</sub> and M<sub>2</sub>C<sub>3</sub> carbides (where M is the metal);
+*[[actinide]]s, when forming MC<sub>2</sub> and M<sub>2</sub>C<sub>3</sub> carbides.
-* [[Calcium carbide]] (CaC<sub>2</sub>) important industrially and an ionic salt
+Most commonly, they are salts of C<sub>2</sub><sup>2<nowiki>&minus;</nowiki></sup> and are called acetylides, ethynides, acetylenediides, or (rarely) percarbides. <br />
-* [[Silicon carbide]] (SiC), carborundum, a covalent compound
+Some ionic carbides contain other anionic species, such as:
-* [[Tungsten carbide]] (often called simply ''carbide'') widely used for cutting tools and an interstitial compound
+*C<sup>4<nowiki>&minus;</nowiki></sup>, sometimes called methanides (or methides) because they hydrolyze to give [[methane]] gas;
-* [[Cementite]] (iron carbide; Fe<sub>3</sub>C) an important constituent of steel
+*C<sub>3</sub><sup>4<nowiki>&minus;</nowiki></sup> ion, sometimes called sesquicarbides, which hydrolyze to give [[methylacetylene]].
-* [[Boron carbide]]
-* [[Tantalum carbide]]
-* [[Titanium carbide]]
-See [[:Category:Carbides]] for a bigger list.
+The naming of ionic carbides is not consistent and can be quite confusing.
+===Acetylides===
+Acetylides contain the polyatomic [[ion]] C<sub>2</sub><sup>2<nowiki>&minus;</nowiki></sup>, in which there is a [[covalent bond|triple bond]] between the two carbon atoms (similar to [[acetylene]]). Examples are carbides of the alkali metals (such as Na<sub>2</sub>C<sub>2</sub>), some alkaline earths (such as [[calcium carbide|CaC<sub>2</sub>]]) and lanthanoids (such as [[lanthanum carbide|LaC<sub>2</sub>]]).
+The C-C bond distance ranges from 109.2 picometers (pm) in CaC<sub>2</sub> (similar to acetylene), to 130.3 pm in LaC<sub>2</sub> and 134pm in [[uranium carbide|UC<sub>2</sub>]].
-==Types of carbides==
+===Methanides===
-===Ionic salts===
-Salt like carbides are formed by the metals of
+Methanides contain the monatomic [[ion]] C<sup>4<nowiki>&minus;</nowiki></sup>. Examples of methanides are Be<sub>2</sub>C and [[aluminum carbide|Al<sub>4</sub>C<sub>3</sub>]].
-*group 1 (the [[alkali metal]]s )
-*group 2 (the [[alkaline earth]]s )
+The C<sup>4<nowiki>&minus;</nowiki></sup> ion is a very strong base and will combine with four [[proton]]s to form [[methane]]. The reaction may be written as follows:
-*group 3 ([[scandium]], [[yttrium]] and [[lanthanum]])
+:C<sup>4<nowiki>&minus;</nowiki></sup> + 4H<sup>+</sup> → CH<sub>4</sub><br/>
-*group 11([[copper(I) acetylide|copper]], [[silver acetylide|silver]] and [[gold]])
-*group 12 ([[zinc]] ,[[cadmium]] and [[mercury (element)|mercury]])
+Methanides commonly react with water to form methane, but reactions with other substances are also common.
-*only [[aluminium carbide|aluminium]] from group 13, ([[gallium]], [[indium]] and [[thallium]] do not appear to form carbides).
-*[[lanthanides]] when forming MC<sub>2</sub> and M<sub>2</sub>C<sub>3</sub> carbides
+===Sesquicarbides===
-*[[actinides]] when forming MC<sub>2</sub> and M<sub>2</sub>C<sub>3</sub> carbides
-Most commonly they are salts of C<sub>2</sub><sup>2<nowiki>&minus;</nowiki></sup> and are called acetylides, ethynides, acetylenediides or very rarely, percarbides. <br />
-Some compounds contain other anionic species:
-*C<sup>4<nowiki>&minus;</nowiki></sup>, sometimes called methanides (or methides) because they hydrolyse to give [[methane]] gas.
-*C<sub>3</sub><sup>4<nowiki>&minus;</nowiki></sup> ion, sometimes called sesquicarbides. these hydrolyse to give [[methylacetylene]].
-The naming of ionic carbides is not consistent and can be quite confusing.
-====Acetylides====
-The [[polyatomic ion]] C<sub>2</sub><sup>2<nowiki>&minus;</nowiki></sup> contains a [[covalent bond|triple bond]] between the two carbon atoms. Examples are the carbides of the alkali metals e.g. Na<sub>2</sub>C<sub>2</sub>, some alkaline earths, e.g. [[calcium carbide|CaC<sub>2</sub>]] and lanthanoids e.g. [[lanthanum carbide|LaC<sub>2</sub>]]. The C-C bond distance ranges from 109.2pm in CaC<sub>2</sub> (similar to ethyne), to 130.3 pm in LaC<sub>2</sub> and 134pm in [[uranium carbide|UC<sub>2</sub>]]. The bonding in LaC<sub>2</sub> has been described in terms of La<sup>III</sup> with the extra electron delocalised into the antibonding orbital on C<sub>2</sub><sup>2<nowiki>&minus</nowiki>;</sup>, explaining the metallic conduction.
-====Methanides====
+The polyatomic ion C<sub>3</sub><sup>4<nowiki>&minus;</nowiki></sup> is found in, for instance, [[lithium carbide|Li<sub>4</sub>C<sub>3</sub>]] and Mg<sub>2</sub>C<sub>3</sub>. The ion is linear and isoelectronic with CO<sub>2</sub>. The C-C distance in Mg<sub>2</sub>C<sub>3</sub> is 133.2 pm.<ref> Fjellvag H. and Pavel K. ''Crystal Structure of Magnesium Sesquicarbide''. Chem. 1992, 31, 3260.</ref> Hydrolysis of Mg<sub>2</sub>C<sub>3</sub> yields [[methylacetylene]] (CH<sub>3</sub>CCH), which was the first indication that it may contain C<sub>3</sub><sup>4<nowiki>&minus;</nowiki></sup>.
-The [[monatomic ion]] C<sup>4<nowiki>&minus;</nowiki></sup> is a very strong base, and will combine with four [[proton]]s to form [[methane]]. Methanides commonly react with water to form methane, however reactions with other substances are common.
-<br />
-C<sup>4<nowiki>&minus;</nowiki></sup> + 4H<sup>+</sup> → CH<sub>4</sub><br/>
-Examples of compounds that contain C<sup>4<nowiki>&minus;</nowiki></sup> are Be<sub>2</sub>C and [[aluminium carbide|Al<sub>4</sub>C<sub>3</sub>]].
-====Sesquicarbides====
+== Covalent carbides==
-The [[polyatomic ion]] C<sub>3</sub><sup>4<nowiki>&minus;</nowiki></sup> is found in e.g. [[lithium carbide|Li<sub>4</sub>C<sub>3</sub>]], Mg<sub>2</sub>C<sub>3</sub>. The ion is linear and is isoelectronic with CO<sub>2</sub>. The C-C distance in Mg<sub>2</sub>C<sub>3</sub> is 133.2 pm.<ref>''Crystal Structure of Magnesium Sesquicarbide'' Fjellvag H. and Pavel K. Inorg. Chem. 1992, 31, 3260</ref> Mg<sub>2</sub>C<sub>3</sub> yields [[methylacetylene]], CH<sub>3</sub>CCH, on hydrolysis which was the first indication that it may contain C<sub>3</sub><sup>4<nowiki>&minus;</nowiki></sup>.
-=== Covalent carbides===
+[[Silicon]] and [[boron]] form covalent carbides. [[Silicon carbide]] (SiC, or carborundum) has two similar crystalline forms, both of which are related to the structure of [[diamond]]. [[Boron carbide]] (B<sub>4</sub>C), on the other hand, has an unusual structure, which includes icosahedral boron units linked by carbon atoms. In this respect, boron carbide is similar to the boron-rich [[boride]]s. Both silicon carbide and boron carbide are very hard, [[refractory]] (heat-resistant) materials. Both are important industrially. Boron also forms other covalent carbides, such as B<sub>25</sub>C.
-Silicon and boron form covalent carbides. [[Silicon carbide]] has two similar crystalline forms, which are both related to the diamond structure. [[Boron carbide]], B<sub>4</sub>C, on the other hand has an unusual structure which includes icosahedral boron units linked by carbon atoms. In this respect boron carbide is similar to the boron rich [[boride]]s.  Both silicon carbide, SiC, (carborundum) and boron carbide, B<sub>4</sub>C are very hard materials and [[refractory]]. Both materials are important industrally. Boron also forms other covalent carbides, e.g. B<sub>25</sub>C.
-===Interstitial carbides===
+==Interstitial carbides==
 ===Properties===
-The carbides of the group 4, 5 and 6 transition metals (with the exception of chromium) are often described as [[interstitial compound]]s. These carbides are chemically quite inert, have metallic properties and are [[refractory]]. Some exhibit a range of stoichiometries, e.g. [[titanium carbide]], TiC. Titanium carbide and [[tungsten carbide]] are important industrially and are used to coat metals in cutting tools.
+The carbides of transition metals of groups four, five, and six (with the exception of [[chromium]]) are often described as [[interstitial compound]]s. They are chemically quite inert, have metallic properties, and are [[refractory]]. Some exhibit a range of stoichiometries (that is, the metal and carbon atoms can be combined in different proportions). Titanium carbide and [[tungsten carbide]] are important industrially and are used to coat metals in cutting tools.
 ===Structure===
-The longheld view is that the carbon atoms fit into octahedral interstices in the metal lattice when the metal atom radius is the greater than 135 pm. If the metal atoms are [[close-packing|cubic close packed]], (face centred cubic), then eventually all the interstices could be filled to give a 1:1 stoichiometry, with the rock salt structure, e.g. [[tungsten carbide]]. When the metal atoms are hexagonal close packed then only half of the interstices are filled, giving a stoichiometry of 2:1, e.g. divanadium carbide, V<sub>2</sub>C. The following table shows actual structures of the metals and their carbides, the notation "h/2" refers to the V<sub>2</sub>C type structure described above, which is an approximate description of the actual structures. The simple view that the lattice of the pure metal "absorbs" carbon atoms is only true for the monocarbides of vanadium, [[vanadium carbide|VC]] and niobium, [[niobium carbide|NbC]].
+The carbon atoms are thought to fit into octahedral interstices in the metal lattice, when the metal atom radius is greater than 135 pm. If the metal atoms are [[close-packing|cubic close packed]] (face-centered cubic), then eventually all the interstices could be filled to give a 1:1 stoichiometry, with the rock salt structure, as in the case of [[tungsten carbide]] (WC). When the metal atoms are hexagonal close packed, then only half the interstices are filled, giving a stoichiometry of 2:1, as in the case of divanadium carbide (V<sub>2</sub>C).
+The following table shows actual structures of metals and their carbides. The notation "h/2" refers to the V<sub>2</sub>C-type structure mentioned above, which is an approximate description of the actual structures. The simple view that the lattice of the pure metal "absorbs" carbon atoms is true only for the monocarbides of vanadium ([[vanadium carbide|VC]]) and niobium ([[niobium carbide|NbC]]).
 {| class="wikitable"
@@ Line 87: / Line 82: @@
 | 160
 | rock salt
 |
 |
 |-
@@ Line 141: / Line 136: @@
 |}
-For a long time the non stoichiometric phases were believed to be disordered with a random filling of the interstices, however short and longer range ordering has been detected<ref> ''Order and disorder in transition metal carbides and nitrides: experimental and theoretical aspects'' C.H. de Novion and J.P. Landesman Pure & Appl. Chem., 57, 10,(1985)1391</ref>.
+For a long time, the non-stoichiometric phases were believed to be disordered, with a random filling of the interstices. However, short and longer range ordering has been detected.<ref>de Novion, C.H., and J.P. Landesman. 1985. "Order and disorder in transition metal carbides and nitrides: experimental and theoretical aspects," ''Pure & Appl. Chem.'' 57 (10): 1391.</ref>
+==Intermediate transition metal carbides==
+In these carbides, 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: Fe<sub>3</sub>C, Fe<sub>7</sub>C<sub>3</sub>, and Fe<sub>2</sub>C. The best-known of these is [[cementite]] (Fe<sub>3</sub>C), 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 are all hydrolyzed by dilute acids and sometimes by water, to give a mixture of [[hydrogen]] and [[hydrocarbon]]s. These compounds share features with both the inert interstitials and the more reactive, salt-like carbides.
+== Some carbides and their uses ==
-===Intermediate transition metal carbides===
+* [[Calcium carbide]] (CaC<sub>2</sub>): It is used for the production of [[acetylene]] and calcium cyanamide (CaCN<sub>2</sub>), which is used in [[fertilizer]]s. It is also important for the desulfurization of [[iron]].
-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, Fe<sub>3</sub>C,  Fe<sub>7</sub>C<sub>3</sub> and Fe<sub>2</sub>C. The best known is [[cementite]], Fe<sub>3</sub>C, which is present in steels.
+* [[Silicon carbide]] (SiC), or carborundum: It is used as an [[abrasive]] and in [[ceramics]].
-These carbides are more reactive than the interstitial carbides, for example the carbides of Cr, Mn, Fe, Co and Ni all are  hydrolyzed by dilute acids and sometimes by water, to give a mixture of hydrogen and hydrocarbons. These compounds share features with both the inert interstitials and the more reactive salt-like carbides.
+* [[Tungsten carbide]] (often called simply ''carbide''): Being extremely hard, it is useful for the manufacture of [[cutting]] [[tool]]s, [[abrasive]]s, and [[Bearing (mechanical)|bearing]]s.
+* [[Cementite]] (iron carbide; Fe<sub>3</sub>C): It is an important constituent of steel.
+* [[Boron carbide]]: It is used in cutting tools, dies, and anti-ballistic [[armor plating]]. It is an effective absorbent of [[neutron]] radiation in nuclear power plants.
+* [[Tantalum carbide]]: It is an extremely [[hardness|hard]], [[refraction (metallurgy)|refractory]], [[ceramic]] material, used in [[tool bit]]s for cutting tools.
+* [[Titanium carbide]]: Similar to tantalum carbide, it is an extremely hard, refractory, ceramic material.
 == See also ==
@@ Line 157: / Line 164: @@
 ==References==
-* Brown Jr., Theodore L., H. Eugene LeMay, Bruce Edward Bursten, and Julia R. Burdge. 2002. ''Chemistry: The Central Science''. 9th ed. Upper Saddle River, NJ: Prentice Hall. ISBN 0130669970.
+* Brown Jr., Theodore L., H. Eugene LeMay, Bruce Edward Bursten, and Julia R. Burdge. 2002. ''Chemistry: The Central Science''. 9th ed. Upper Saddle River, NJ: Prentice Hall.
+* Chang, Raymond. 2006. ''Chemistry''. 9th ed. New York, NY: McGraw-Hill Science/Engineering/Math.
-* Chang, Raymond. 2006. ''Chemistry''. 9th ed. New York, NY: McGraw-Hill Science/Engineering/Math. ISBN 0073221031.
 * Cotton, F. Albert, and Geoffrey Wilkinson. 1980. ''Advanced Inorganic Chemistry''. 4th ed. New York, NY: Wiley. ISBN 0-471-02775-8.
+* Ettmayer, Peter, and Walter Lengauer. 1994. Carbides: transition metal solid state chemistry. In ''Encyclopedia of Inorganic Chemistry''. Editor in chief R. Bruce King. Chichester, UK: Wiley. ISBN 0-471-93620-0.
-* Ettmayer, Peter, and Walter Lengauer. 1994. Carbides: transition metal solid state chemistry. In ''Encyclopedia of Inorganic Chemistry''. Editor in chief  R. Bruce King Pub 1994 John Wiley & Sons ISBN 0-471-93620-0.
+* Greenwood, N.N., and A. Earnshaw. 1998. ''Chemistry of the Elements''. 2nd ed. Oxford, U.K.; Burlington, MA: Butterworth-Heinemann, Elsevier Science. ISBN 0750633654. Online version available [http://www.knovel.com/knovel2/Toc.jsp?BookID=402&VerticalID=0 here] Retrieved January 4, 2008.
-* Greenwood, N.N., and A. Earnshaw. 1998. ''Chemistry of the Elements''. 2nd ed. Oxford, U.K.; Burlington, MA: Butterworth-Heinemann, Elsevier Science. ISBN 0750633654. Online version available [http://www.knovel.com/knovel2/Toc.jsp?BookID=402&VerticalID=0 here]. Retrieved August 11, 2007.
 {{Inorganic compounds of carbon}}