Aluminium carbide

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Aluminium carbide
Unit cell ball and stick model of aluminium carbide
Names
Preferred IUPAC name
Aluminium carbide
Other names
Tetraaluminium tricarbide
Identifiers
3D model (
JSmol
)
ChemSpider
ECHA InfoCard
 100.013.706 Edit this at Wikidata
EC Number
  • 215-076-2
MeSH Aluminum+carbide
UN number 1394
  • InChI=1S/3C.4Al/q3*-4;4*+3 checkY
    Key: TWHBEKGYWPPYQL-UHFFFAOYSA-N checkY
  • InChI=1/3C.4Al/q3*-4;4*+3
    Key: TWHBEKGYWPPYQL-UHFFFAOYAR
  • [Al+3].[Al+3].[Al+3].[Al+3].[C-4].[C-4].[C-4]
Properties
Al4C3
Molar mass 143.95853 g/mol
Appearance colorless (when pure) hexagonal crystals[1]
Odor odorless
Density 2.36 g/cm3[1]
Melting point 2,100 °C (3,810 °F; 2,370 K)
Boiling point decomposes at 1400 °C[2]
reacts to make natural gas
Structure
Rhombohedral, hR21, space group[2]
R3m（No. 166）
a = 0.3335 nm, b = 0.3335 nm, c = 0.85422 nm
α = 78.743°, β = 78.743°, γ = 60°
Thermochemistry
116.8 J/mol K
88.95 J/mol K
Std enthalpy of
formation
(ΔfH⦵298)
 -209 kJ/mol
-196 kJ/mol
Hazards
GHS labelling:
GHS02: FlammableGHS07: Exclamation mark
Warning
H261, H315, H319, H335
P231+P232, P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P370+P378, P402+P404, P403+P233, P405, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 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 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazard W: Reacts with water in an unusual or dangerous manner. E.g. sodium, sulfuric acid
2
2
2
W
Safety data sheet (SDS) Fisher Scientific
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Aluminium carbide, chemical formula Al4C3, is a carbide of aluminium. It has the appearance of pale yellow to brown crystals. It is stable up to 1400 °C. It decomposes in water with the production of methane.

Structure

Aluminium carbide has an unusual crystal structure that consists of alternating layers of Al2C and Al2C2. Each aluminium atom is coordinated to 4 carbon atoms to give a tetrahedral arrangement. Carbon atoms exist in 2 different binding environments; one is a deformed octahedron of 6 Al atoms at a distance of 217 pm. The other is a distorted trigonal bipyramidal structure of 4 Al atoms at 190–194 pm and a fifth Al atom at 221 pm.[3][4] Other carbides (

methides
) also exhibit complex structures.

Reactions

Aluminium carbide hydrolyses with evolution of methane. The reaction proceeds at room temperature but is rapidly accelerated by heating.[5]

Al4C3 + 12 H2O → 4 Al(OH)3 + 3 CH4

Similar reactions occur with other protic reagents:[1]

Al4C3 + 12 HCl → 4 AlCl3 + 3 CH4

Reactive hot isostatic pressing (hipping) at ≈40 MPa of the appropriate mixtures of Ti, Al4C3 graphite, for 15 hours at 1300 °C yields predominantly single-phase samples of Ti2AlC0.5N0.5, 30 hours at 1300 °C yields predominantly single-phase samples of Ti2AlC (Titanium aluminium carbide).[6]

Preparation

Aluminium carbide is prepared by direct reaction of aluminium and carbon in an electric arc furnace.[3]

4 Al + 3 C → Al4C3

An alternative reaction begins with alumina, but it is less favorable because of generation of carbon monoxide.

2 Al2O3 + 9 C → Al4C3 + 6 CO

Silicon carbide also reacts with aluminium to yield Al4C3. This conversion limits the mechanical applications of SiC, because Al4C3 is more brittle than SiC.[7]

4 Al + 3 SiC → Al4C3 + 3 Si

In aluminium-matrix composites reinforced with silicon carbide, the chemical reactions between silicon carbide and molten aluminium generate a layer of aluminium carbide on the silicon carbide particles, which decreases the strength of the material, although it increases the wettability of the SiC particles.

silica coating, or using a layer of sacrificial metal.[9]

An aluminium-aluminium carbide composite material can be made by mechanical alloying, by mixing aluminium powder with graphite particles.

Occurrence

Small amounts of aluminium carbide are a common impurity of technical calcium carbide. In electrolytic manufacturing of aluminium, aluminium carbide forms as a corrosion product of the graphite electrodes.[10]

In

titanium boride.[citation needed
]

Applications

Aluminium carbide particles finely dispersed in aluminium matrix lower the tendency of the material to creep, especially in combination with silicon carbide particles.[11]

Aluminium carbide can be used as an

cutting tools.[12] It has approximately the same hardness as topaz.[13]

See also

References

  1. ^
    ISBN 978-3-11-011451-5
    .
  2. ^ a b Gesing, T. M.; Jeitschko, W. (1995). "The Crystal Structure and Chemical Properties of U2Al3C4 and Structure Refinement of Al4C3". 50. Zeitschrift für Naturforschung B, A journal of chemical sciences: 196–200. {{cite journal}}: Cite journal requires |journal= (help)
  3. ^
    ISBN 978-0-08-037941-8
    .
  4. ISSN 0038-1098
    .
  5. ^ qualitative inorganic analysis. CUP Archive. 1954. p. 102.
  6. S2CID 138590417
    .
  7. ISBN 978-1-84882-830-8
    .
  8. S2CID 24683423
    .
  9. ^ Guillermo Requena. "A359/SiC/xxp: A359 Al alloy reinforced with irregularly shaped SiC particles". MMC-ASSESS Metal Matrix Composites. Archived from the original on 2007-08-15. Retrieved 2007-10-07.
  10. ISBN 978-3-87017-270-1
    .
  11. ^ S.J. Zhu; L.M. Peng; Q. Zhou; Z.Y. Ma; K. Kucharova; J. Cadek (1998). "Creep behaviour of aluminum strengthened by fine aluminum carbide particles and reinforced by silicon carbide particulates DS Al-SiC/Al4C3composites". Acta Technica CSAV (5): 435–455. Archived from the original (abstract) on 2005-02-22.
  12. ^ Jonathan James Saveker et al. "High speed cutting tool" U.S. patent 6,033,789, Issue date: Mar 7, 2000
  13. ^ E. Pietsch, ed.: "Gmelins Hanbuch der anorganischen Chemie: Aluminum, Teil A", Verlag Chemie, Berlin, 1934–1935.
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