Tantalum carbide

Tantalum carbide
γ-tantalum carbide in cubic phase
Powder of tantalum carbide
Names
IUPAC name
Tantalum carbide
Other names
Tantalum(IV) carbide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.031.914 Edit this at Wikidata
EC Number
  • (TaC): 235-118-3
  • (TaC0.5): 235-119-9
UNII
  • (TaC): InChI=1S/C.Ta/q-1;+1
    Key: DUMHRFXBHXIRTD-UHFFFAOYSA-N
  • (TaC0.5): InChI=1S/C.2Ta
    Key: VDBAWDHDCVOEAA-UHFFFAOYSA-N
  • (TaC): [Ta+]#[C-]
  • (TaC0.5): [C].[Ta].[Ta]
Properties
TaC
Molar mass 192.96 g/mol
Appearance Brown-gray powder
Odor Odorless
Density 14.3–14.65 g/cm3 (TaC)
15.1 g/cm3 (TaC0.5)[1]
Melting point 3,768 °C (6,814 °F; 4,041 K)
(TaC)[3]
3,327 °C (6,021 °F; 3,600 K)
(TaC0.5)[1]
Boiling point 4,780–5,470 °C (8,640–9,880 °F; 5,050–5,740 K)
(TaC)[1][2]
Insoluble
Solubility Soluble in HF-HNO3 mixture[1]
Thermal conductivity 21 W/m·K[2]
Thermochemistry
36.71 J/mol·K[4]
42.29 J/mol·K
−144.1 kJ/mol
Related compounds
Related refractory ceramic materials
 Zirconium nitride
Niobium carbide
Zirconium carbide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Tantalum carbides (TaC) form a family of binary chemical compounds of tantalum and carbon with the empirical formula TaCx, where x usually varies between 0.4 and 1. They are extremely hard, brittle, refractory ceramic materials with metallic electrical conductivity. They appear as brown-gray powders, which are usually processed by sintering.

Being important cermet materials, tantalum carbides are commercially used in tool bits for cutting applications and are sometimes added to tungsten carbide alloys.[5]

The melting points of tantalum carbides was previously estimated to be about 3,880 °C (4,150 K; 7,020 °F) depending on the purity and measurement conditions; this value is among the highest for binary compounds.[6][7] And only tantalum hafnium carbide was estimated to have a higher melting point of 3,942 °C (4,215 K; 7,128 °F).[8] However new tests have conclusively proven that TaC actually has a melting point of 3,768 °C and both tantalum hafnium carbide and hafnium carbide have higher melting points.[9]

  1. ^ a b c d Lide, David R., ed. (2009). CRC Handbook of Chemistry and Physics (90th ed.). Boca Raton, Florida: CRC Press. ISBN 978-1-4200-9084-0.
  2. ^ a b US 5196273, Tsantrizos, Peter; Mavropoulos, Lakis T. & Shanker, Kartik et al., "Tantalum carbide composite materials", published 1993-03-23, assigned to Noranda Inc. 
  3. ^ Cedillos-Barraza, Omar; Manara, Dario; Boboridis, K.; Watkins, Tyson; Grasso, Salvatore; Jayaseelan, Daniel D.; Konings, Rudy J. M.; Reece, Michael J.; Lee, William E. (2016). "Investigating the highest melting temperature materials: A laser melting study of the TaC-HFC system". Scientific Reports. 6: 37962. Bibcode:2016NatSR...637962C. doi:10.1038/srep37962. PMC 5131352. PMID 27905481.
  4. ^ Tantalum carbide in Linstrom, Peter J.; Mallard, William G. (eds.); NIST Chemistry WebBook, NIST Standard Reference Database Number 69, National Institute of Standards and Technology, Gaithersburg (MD) (retrieved 2014-07-02)
  5. ^ Emsley, John (11 August 2003). Nature's building blocks: an A-Z guide to the elements. Oxford University Press. pp. 421–. ISBN 978-0-19-850340-8. Retrieved 2 May 2011.
  6. ^ The claim of melting point of 4,000 °C (4,270 K; 7,230 °F) in TaC0.89 is based not on actual measurement but on an extrapolation of the phase diagram, using an analogy with NbC, see Emeléus
  7. ^ Emeléus, Harry (1968). Advances in Inorganic Chemistry and Radiochemistry. Academic Press. pp. 174–176. ISBN 978-0-12-023611-4. Retrieved 3 May 2011.
  8. ^ Agte, C.; Alterthum, H. (1930). "Researches on Systems with Carbides at High Melting Point and Contributions to the Problem of Carbon Fusion". Zeitschrift für technische Physik. 11: 182–191. ISSN 0373-0093.
  9. ^ "New record set for world's most heat resistant material".