Tantalum hafnium carbide

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Tantalum hafnium carbide
Identifiers
3D model (
JSmol
)
ECHA InfoCard
 100.068.426 Edit this at Wikidata
EC Number
  • 275-291-2
  • InChI=1S/5C.Hf.4Ta
    Key: SWQWZVPEXQVZCJ-UHFFFAOYSA-N
  • [C].[C].[C].[C].[C].[Hf].[Ta].[Ta].[Ta].[Ta]
Properties
Ta4HfC5
Melting point 3,905 °C; 7,061 °F; 4,178 K
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 hafnium carbide is a refractory chemical compound with a general formula TaxHfyCx+y, which can be considered as a solid solution of tantalum carbide and hafnium carbide. It was originally thought to have the highest melting of any known substance but new research has proven that hafnium carbonitride has a higher melting point.

Properties

Individually, tantalum and hafnium carbide have the highest

binary compounds, 4,041 K (3,768 °C; 6,814 °F) and 4,232 K (3,959 °C; 7,158 °F), respectively,[1] and their "alloy" with a composition Ta4HfC5 has a melting point of 4,178 K (3,905 °C; 7,061 °F).[2]

Very few measurements of melting point in tantalum hafnium carbide have been reported, because of the obvious experimental difficulties at extreme temperatures. A 1965 study of the TaC-HfC solid solutions at temperatures 2,225–2,275 °C found a minimum in the vaporization rate and thus maximum in the thermal stability for Ta4HfC5. This rate was comparable to that of

µm powder[4] at a price of $9,540/kg (99.0% purity).[5]

In 2015, atomistic simulations predicted that hafnium carbonitride could have a melting point exceeding Ta4Hf1C5 by 200 K.[6] This was later verified by experimental evidence in 2020.[7]

Structure

Individual tantalum and hafnium carbides have a

X-ray diffraction data is 13.6 g/cm3 for Ta0.5Hf0.5C.[9][10] Hexagonal NiAs-type structure (space group P63/mmc, No. 194, Pearson symbol hP4) with a density of 14.76 g/cm3 was reported for Ta0.9Hf0.1C0.5.[9]

See also

References

  1. PMID 27905481
    .
  2. ^ "New record set for world's most heat resistant material".
  3. doi:10.1111/j.1151-2916.1965.tb14760.x. Archived from the original
    on 27 March 2012.
  4. ^ Goodfellow catalogue, February 2009, p. 102
  5. ^ NIAC 7600-039 FINAL REPORT, NASA Institute for Advanced Concepts – A Realistic Interstellar Explorer, 14 October 2003, p. 55
  6. ISSN 1098-0121
    .
  7. ^ "Scientists Create World's Most Heat Resistant Material with Potential Use for Spaceplanes". Forbes.
  8. doi:10.1016/j.jallcom.2007.08.018
    .
  9. ^
    doi:10.1007/BF00903490
    .
  10. doi:10.1007/BF00903181
    .
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