Tantalum carbide TaC

spore: profile
id: tantalum-carbide
spore_version: 0.2
family: carbide-nitride-boride-ceramics
name: Tantalum carbide
abbreviation: TaC
role: ultra-high-temperature ceramic (carbide), a candidate for hypersonic flight structures and a hard coating for hot tools
category: ceramics
type: carbides
summary: |
  Tantalum carbide is a very hard, very high melting point ceramic carbide. A supplier safety data sheet gives a melting point of 3880 degC and a density of 13.9 g/cm3 at 20 degC. PubChem gives 14.5 g/cm3 at 25 degC. A CVD coating specification gives a hardness of 1790 kg/mm2, a thermal expansion coefficient of 6.3 (10-6/degC) and a thermal conductivity of 22 W/mK for TaC coatings, with an oxidation temperature of 700 degC. A 2013 study found that dense TaC held at about 3000 degC in oxygen forms a molten oxide that gives temporary protection but also attacks the ceramic. Tantalum is mined mostly in Congo (Kinshasa) and Rwanda (USGS 2026).
best_for: Very hard, very high melting point ceramic parts and coatings where a protective layer handles oxidation, such as coatings for steel moulds and a candidate for hypersonic structures
weakest_at: Oxidation in air from about 700 degC for coatings (CVD specification), and a flammable powder (H228 in the supplier SDS)
identity:
  formula: TaC
  cas: 12070-06-3
  source: pubchem-tac
  where: CAS section of the PubChem record (CID 159432); the same CAS number is printed in Section 1 of the Stanford Advanced Materials SDS
tags:
  environments: []
  stresses:
    - extreme-heat
  applications:
    - heat-shields
    - structures
    - propulsion-and-tanks
properties:
  - benchmark: density
    label: Density, TaC (PubChem experimental)
    value: 14.5
    unit: g/cm3
    scope: material
    conditions:
      temperature: 25 degC
    method: Experimental Properties, Density section, printed as 14.5 @25 degC
    status: ground
    source: pubchem-tac
    where: Experimental Properties, Density section
  - benchmark: density
    label: Density, TaC powder (supplier SDS)
    value: 13.9
    unit: g/cm3
    scope: material
    conditions:
      temperature: 20 degC
      form: powder, as sold
    method: Section 9, Density row, printed as 13.9 g/cm3 at 20 degC
    status: ground
    note: A powder supplier figure. It is not a measured value for dense TaC.
    source: sam-tac-sds
    where: Section 9 (Physical and chemical properties), Density row
  - benchmark: density
    label: Density, TaC CVD coating (supplier specification)
    value: 15
    unit: g/cm3
    scope: material
    conditions:
      form: CVD coating, standard thickness 10 to 20 micrometre (as printed)
    method: Properties table, Density row, TaC column
    status: ground
    note: A coating value, not bulk density. The CVD specification prints 15.0 for TaC.
    source: cvd-tac-spec
    where: Properties table, Density row, TaC column
  - benchmark: melting_point
    label: Melting point, TaC powder (supplier SDS)
    value: 3880
    unit: degC
    scope: material
    conditions:
      form: powder, as sold
    method: Section 9, Melting point/Melting range row, printed as 3880 degC (7016 degF)
    status: ground
    source: sam-tac-sds
    where: Section 9, Melting point/Melting range row
  - benchmark: boiling_point
    label: Boiling point, TaC powder (supplier SDS)
    value: 5500
    unit: degC
    scope: material
    conditions:
      form: powder, as sold
    method: Section 9, Boiling point/Boiling range row, printed as 5500 degC (9932 degF)
    status: ground
    source: sam-tac-sds
    where: Section 9, Boiling point/Boiling range row
  - benchmark: hardness
    label: Hardness, TaC CVD coating (supplier specification)
    value: 1790
    unit: kg/mm2
    scope: material
    conditions:
      form: CVD coating
      test: not stated in the specification
    method: Properties table, Hardness row, TaC column (printed as 1790)
    status: ground
    note: A coating value, not bulk hardness. The same specification gives 2400 for NbC, so the hardness figure is only for TaC coatings. Custom property name, as in the zirconium carbide profile.
    source: cvd-tac-spec
    where: Properties table, Hardness row, TaC column
  - benchmark: cte
    label: Coefficient of thermal expansion, TaC CVD coating
    value: 6.3
    unit: 10-6/degC
    scope: material
    conditions:
      form: CVD coating
      temperature: not stated in the specification
    method: Properties table, Thermal Expansion Coefficient row, TaC column (printed as 6.3, unit 10-6/degC)
    status: ground
    note: A coating value with no temperature range printed.
    source: cvd-tac-spec
    where: Properties table, Thermal Expansion Coefficient row, TaC column
  - benchmark: thermal_conductivity
    label: Thermal conductivity, TaC CVD coating
    value: 22
    unit: W/mK
    scope: material
    conditions:
      form: CVD coating
      temperature: not stated in the specification
    method: Properties table, Thermal Conductivity row, TaC column (printed as 22 W/mK)
    status: ground
    note: A coating value. Bulk TaC conductivity was not found in a source read in this run.
    source: cvd-tac-spec
    where: Properties table, Thermal Conductivity row, TaC column
  - benchmark: flexural_strength
    label: Flexural strength, TaC CVD coating (range)
    value: 96
    value_high: 291
    bound: range
    unit: MPa
    scope: material
    conditions:
      form: CVD coating
      test: not stated in the specification
    method: Properties table, Flexural Strength row, TaC column (printed as 96-291 MPa)
    status: ground
    note: A coating range printed by the supplier. The spread is wide and no test method is given.
    source: cvd-tac-spec
    where: Properties table, Flexural Strength row, TaC column
  - benchmark: oxidation_resistance_temp
    label: Oxidation temperature, TaC CVD coating
    value: 700
    unit: degC
    scope: material
    conditions:
      form: CVD coating
      atmosphere: air (not stated in the specification)
    method: Properties table, Oxidation Temperature row, TaC column (printed as 700 degC)
    status: ground
    note: Custom property name, as in the zirconium carbide profile. A single printed figure for a coating, not a rate or a test result.
    source: cvd-tac-spec
    where: Properties table, Oxidation Temperature row, TaC column
corrosion:
  - environment: Oxidizing air, TaC CVD coating
    headline: The CVD coating specification lists an oxidation temperature of 700 degC for TaC.
    effect: The specification prints 700 degC for TaC, against 500 degC for Ta and 850 degC for Nb, for coatings 10 to 20 micrometre thick. It is one listed figure, not a rate or a test description.
    rating: moderate
    conditions:
      temperature: 700 degC (printed as oxidation temperature)
      atmosphere: air
      form: CVD coating
    source: cvd-tac-spec
    where: Properties table, Oxidation Temperature row
  - environment: Oxygen at about 3000 degC, dense TaC (2013 study)
    headline: At about 3000 degC in oxygen, the molten oxide slows oxidation for a time but also attacks the dense ceramic.
    effect: The abstract says the molten oxide may give temporary resistance to rapid oxidation and may repair thermal shock cracks, but the liquid is seen to attack the dense ceramic both chemically and mechanically. The authors suggest TaC dissolves in the oxide melt, and the dissolved carbon is then oxidised to gas.
    rating: severe
    conditions:
      temperature: 3000 degC
      atmosphere: oxygen
      form: dense TaC
    source: lashtabeg-2013
    where: Abstract
  - environment: Water
    headline: TaC is insoluble in water according to the supplier safety data sheet.
    effect: The SDS lists TaC as insoluble in water. No corrosion test of TaC in water was read.
    rating: none
    conditions:
      medium: water
    source: sam-tac-sds
    where: Section 9, Solubility in / Miscibility with Water
risks:
  hazards:
    - text: Stanford Advanced Materials SDS for TaC powder (CAS 12070-06-3) classifies it as Flam. Sol. 2, H228 Flammable solid, with the GHS02 flame pictogram and signal word Warning. Precautionary statements include P210, keep away from heat, sparks and open flames.
      ghs:
        - H228
      source: sam-tac-sds
      where: Section 2 (Hazards identification)
    - text: 'PubChem aggregates company reports: 36 of 42 say TaC does not meet GHS hazard criteria, and 6 of 42 give hazard codes. The fetched page does not print those codes.'
      ghs: []
      source: pubchem-tac
      where: GHS Classification, ECHA C&L Notifications Summary
  failure_risks:
    - mode: Oxide melt attack at very high temperature
      trigger: Dense TaC held at about 3000 degC in oxygen
      consequence: The molten oxide that gives temporary protection also dissolves TaC and attacks it chemically and mechanically, so the protective layer is not stable on its own.
      severity: high
      source: lashtabeg-2013
      where: Abstract
    - mode: Oxidation of a coating in air
      trigger: Oxidizing air above about 700 degC
      consequence: The CVD specification lists 700 degC as the oxidation temperature for a TaC coating. The figure is 150 degC lower than the 850 degC it gives for Nb.
      severity: moderate
      source: cvd-tac-spec
      where: Properties table, Oxidation Temperature row
    - mode: Ignition of the powder
      trigger: Heat, sparks, or electrostatic charge near the powder
      consequence: The SDS classes the powder as a flammable solid (H228) and advises protection against electrostatic charges.
      severity: moderate
      source: sam-tac-sds
      where: Section 2 and Section 7 (protection against electrostatic charges)
  side_effects: []
  handling:
    - text: Keep away from heat, sparks and open flames, and protect against electrostatic charges (SDS P210 and Section 7).
      source: sam-tac-sds
      where: Section 2 (precautionary statements); Section 7
    - text: Store in a cool, dry place in tightly closed containers, away from oxidizing agents (SDS Section 7).
      source: sam-tac-sds
      where: Section 7, Storage
    - text: The powder reacts with strong oxidizing agents. In a fire it gives carbon monoxide, carbon dioxide and metal oxide fume (SDS Sections 10 and 5).
      source: sam-tac-sds
      where: Section 10 (reactivity, incompatible materials, hazardous decomposition)
  mitigations:
    - text: The 2013 study notes that the molten oxide layer gives temporary resistance to rapid oxidation and may repair thermal shock cracks, but that the liquid also attacks the ceramic, so the layer is not a complete protection.
      source: lashtabeg-2013
      where: Abstract
uses:
  - application: heat-shields
    device: Hypersonic flight structures (candidate, not flown)
    example: The 2013 study describes dense TaC as one of the candidate ultra-high temperature ceramics for hypersonic flight, and tests it at 3000 degC in oxygen. The study is a laboratory test, not a flight record.
    source: lashtabeg-2013
    where: Abstract (first sentences)
  - application: structures
    device: Cutting tools, cemented carbide tools and abrasives
    example: PubChem lists TaC as used in cutting tools, cemented carbide tools and as an abrasive. Wikipedia says tantalum carbides are used commercially in tool bits for cutting and are added to tungsten carbide alloys.
    source: pubchem-tac
    where: Uses, Sources/Uses (HSDB)
  - application: structures
    device: Coatings on steel moulds, sharp instruments and graphite furniture for LED production
    example: The CVD coating specification says TaC is used to coat steel moulds and sharp instruments for high wear resistance, and to coat graphite furniture used in LED production.
    source: cvd-tac-spec
    where: Applications, TaC line
supply:
  - subject: Tantalum (the metal half, from tantalum ores and concentrates)
    abundance: 'USGS: world mine production in 2025 (estimated) was 2,500 tons, as printed, with identified world resources most of which are in Australia, Brazil, Canada and China. No crustal abundance figure for tantalum was read in this run.'
    producers:
      - country: Congo (Kinshasa)
        share_percent: 52
        year: 2025
      - country: Rwanda
        share_percent: 16
        year: 2025
      - country: Nigeria
        share_percent: 15.6
        year: 2025
      - country: China
        share_percent: 3.2
        year: 2025
      - country: Australia
        share_percent: 2
        year: 2025
    critical_lists:
      - list: EU critical raw materials list (Regulation (EU) 2024/1252, as shown on the European Commission page)
        listed: true
    recycling: 'USGS: tantalum was recycled mostly from new scrap from electronic components and from cemented carbide and superalloy scrap. The recycled amount is not available, but it may be as much as 30% of consumption by domestic primary processors.'
    substitutes:
      - 'USGS: niobium and tungsten can substitute for tantalum in carbides, with performance loss or higher cost.'
    source: usgs-mcs2026-tantalum
    where: World Mine Production and Reserves table, 2025e column (shares calculated by Space Mushroom against the printed world total of 2,500; the Brazil and Mozambique rows are not used because the table layout is garbled); Recycling; Substitutes; EU list on the European Commission page
  - subject: Tantalum metal and powder (the feedstock form used to make carbide)
    abundance: 'USGS, U.S. import sources 2021 to 2024 for tantalum metal and powder: China 47 percent, Germany 25 percent, Kazakhstan 16 percent, Thailand 4 percent and other 8 percent. These are import shares, not production shares.'
    producers: []
    critical_lists: []
    recycling: 'USGS: recycling is covered under the tantalum entry above.'
    substitutes: []
    source: usgs-mcs2026-tantalum
    where: Import Sources (2021 to 2024), tantalum metal and powder
media: []
documents:
  - title: Stanford Advanced Materials, Safety Data Sheet, Tantalum Carbide Powder (CAS 12070-06-3, revised 29/11/2022)
    type: sds
    url: https://powder.samaterials.com/tds/sc/1734506246-Tantalum%20Carbide%20Powder.pdf
    year: 2022
  - title: CVD coatings technical specification, Group 5b, Metals and Carbides (Ta, Nb, TaC, NbC)
    type: report
    url: https://www.cvd.co.uk/_files/ugd/4b1e48_266286c199c74eff81656bc1a2e4b312.pdf
  - title: PubChem compound record CID 159432, Tantalum carbide (GHS classification, uses, experimental melting point and density)
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/159432
    year: 2026
  - title: Lashtabeg, Smart, Riley, Gillen and Drennan, The effect of extreme temperature in an oxidising atmosphere on dense tantalum carbide (TaC), Journal of Materials Science (2013), doi 10.1007/s10853-012-6740-4
    type: paper
    url: https://apo.ansto.gov.au/items/aeb3b687-b6a9-76a5-e053-150a9d89ded9/full
    year: 2013
  - title: USGS Mineral Commodity Summaries 2026, Tantalum
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tantalum.pdf
    year: 2026
gaps:
  - No elastic modulus for TaC was found in a source read in this run. Wikipedia gives a value, but Wikipedia is used here for composition and history only, so it is not recorded.
  - The Wikipedia melting point of 3768 degC (after newer tests) conflicts with the SDS (3880 degC). It is recorded in the notes and not used as a value.
  - Hardness, thermal expansion, thermal conductivity, electrical resistivity, flexural strength and density (15.0) are coating values from the CVD specification. No bulk TaC value for these was read in this run.
  - The 1967 NASA report (NTRS 19670028948) was read for the sign of the Hall coefficient only. Its resistivity figures were not found in the text and were not used. The CVD coating resistivity (printed 3.0x10-5 ohm cm) was left out because its exponent form could not be checked as a plain number.
  - 'Crystal structure: Wikipedia gives a cubic rock-salt structure for TaCx with x from 0.7 to 1.0, but Wikipedia is used here for composition only, so crystal_system is left out. No other structure source was read.'
  - Crustal abundance of tantalum was not found in a source read in this run.
  - The USGS 2025 critical minerals page fetched in this run did not contain the word tantalum, so the USGS critical-mineral status is not recorded. The EU list entry comes from the European Commission page.
  - Mine production for Brazil and Mozambique could not be read reliably because the USGS table layout is garbled, so those shares are left out.
  - The PubChem ECHA summary says 6 of 42 reports give hazard codes, but the fetched text does not print the codes. The SDS H228 classification is used instead.
  - The SDS states both H228 Flammable solid (Regulation EC 1272/2008) and the older 'Highly flammable' wording. The H228 entry is used.
  - The American Elements TaC SDS and the Birmingham TaC oxyacetylene paper could not be opened (blocked or landing page only). The MDPI TaC-HfC thermal paper also returned no content.
  - Only the abstract of the 2013 oxidation study was read. The full text, oxidation rate constants and test details are not recorded.
  - No space use, NASA or ESA flight record for TaC was found. The hypersonic use is a candidate statement from a laboratory study.
  - No UNS, EN, DIN, JIS, AISI or ASTM designation for TaC was printed in a source read in this run. Only the CAS number is recorded.
  - 'Custom property names used because they are not in spores/property-canon.yaml: hardness, oxidation_resistance_temp.'
sources:
  pubchem-tac:
    title: PubChem compound record CID 159432, Tantalum carbide (GHS classification, uses, experimental melting point and density, CAS 12070-06-3)
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/159432/JSON
    kind: database
    license: PubChem public database
  sam-tac-sds:
    title: Stanford Advanced Materials, Safety Data Sheet, Tantalum Carbide Powder (CAS 12070-06-3, revised 29/11/2022)
    url: https://powder.samaterials.com/tds/sc/1734506246-Tantalum%20Carbide%20Powder.pdf
    kind: datasheet
    license: supplier document, cited not reproduced
  cvd-tac-spec:
    title: CVD coatings technical specification, Group 5b, Metals and Carbides (Ta, Nb, TaC, NbC)
    url: https://www.cvd.co.uk/_files/ugd/4b1e48_266286c199c74eff81656bc1a2e4b312.pdf
    kind: datasheet
    license: supplier document, cited not reproduced
  lashtabeg-2013:
    title: Lashtabeg A, Smart M, Riley D, Gillen AL, Drennan J, The effect of extreme temperature in an oxidising atmosphere on dense tantalum carbide (TaC), Journal of Materials Science (2013), doi 10.1007/s10853-012-6740-4
    url: https://apo.ansto.gov.au/items/aeb3b687-b6a9-76a5-e053-150a9d89ded9/full
    kind: paper
    license: ANSTO repository record
  usgs-mcs2026-tantalum:
    title: Mineral Commodity Summaries 2026, Tantalum
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tantalum.pdf
    kind: report
    license: public domain (USGS)
  ec-crm:
    title: Critical raw materials (European Commission, list under Regulation (EU) 2024/1252)
    url: https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en
    kind: web
    license: European Commission web page
  wikipedia-tac:
    title: Wikipedia, Tantalum carbide (composition, preparation and history only)
    url: https://en.wikipedia.org/wiki/Tantalum_carbide
    kind: web
    license: CC BY-SA 4.0
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 10
  unreachable: 3
  caveats: 6
  note: Written in this run from the Stanford Advanced Materials SDS (revised 2022), a CVD coating specification, PubChem (CID 159432), a 2013 oxidation study (abstract), the USGS MCS 2026 tantalum chapter, the EU critical raw materials page, the 1967 NASA Hall-coefficient report (sign only) and Wikipedia (composition and history only). The American Elements SDS, the Birmingham PDF and the MDPI TaC paper were not readable.
story:
  recipe:
    line: Tantalum carbide is a compound of tantalum and carbon, written as TaCx in the literature, where the carbon content x can vary (Wikipedia). Its crystal form is cubic rock-salt for the carbon-rich compositions (Wikipedia). Powders are made by heating tantalum and graphite in vacuum or argon (Wikipedia).
    parts:
      - name: Tantalum
        symbol: Ta
        role: The metal atom in the rock-salt lattice. Its strong bonds with carbon give TaC its high melting point and hardness.
      - name: Carbon
        symbol: C
        role: The non-metal atom in the lattice. Carbon content (x in TaCx) sets the stoichiometry.
  risk_groups:
    - title: For people
      level: 0
      verdict: Flammable solid (H228) per supplier SDS
      lead: The supplier SDS classifies the powder only as a flammable solid. PubChem's company reports mostly say it is not classified.
      points:
        - label: The powder
          line: The SDS gives H228 Flammable solid, signal word Warning, and advises keeping the powder away from heat, sparks and open flames.
        - label: Electrostatic charge
          line: The SDS advises protection against electrostatic charges, because the powder is a flammable solid.
        - label: In a fire
          line: The SDS lists carbon monoxide, carbon dioxide and metal oxide fume as decomposition products.
    - title: If a part fails
      lead: These figures come from laboratory tests and coating specifications, not from field incidents.
      points:
        - label: Oxide melt
          line: At about 3000 degC in oxygen, the molten oxide layer attacks dense TaC chemically and mechanically (2013 study).
        - label: Coating limit
          line: The CVD specification gives an oxidation temperature of 700 degC for a TaC coating.
  why: 'Tantalum carbide is a very hard, very high melting point ceramic carbide. The supplier SDS gives a melting point of 3880 degC. The sources emphasise its hardness and very high melting point, and the 2013 study tests it as an ultra-high temperature ceramic for hypersonic flight. Oxidation is the main limit: the protective oxide melt is not stable on its own, and the coating specification gives 700 degC as the oxidation temperature.'
  uses:
    - where: Hypersonic flight structures (candidate)
      line: The 2013 study describes dense TaC as one of the candidate ultra-high temperature ceramics for hypersonic flight. It is a laboratory result, not a flight record.
    - where: Cutting tools and abrasives
      line: PubChem and Wikipedia both say TaC is used in cutting tools, cemented carbide tools and abrasives, and is added to tungsten carbide alloys.
    - where: Coatings for moulds and LED furnace parts
      line: The CVD specification says TaC is used to coat steel moulds and sharp instruments, and graphite furniture used in LED production.
  can_do:
    - label: Melting
      benchmark: melting_point
      value: 3880 degC
      line: The SDS gives 3880 degC. Wikipedia reports a newer figure of 3768 degC, which conflicts with it.
    - label: Density
      benchmark: density
      value: 13.9 g/cm3
      line: The SDS gives 13.9 g/cm3 at 20 degC for the powder. The CVD coating specification gives 15.0 g/cm3 for a coating.
    - label: Hardness
      benchmark: hardness
      value: 1790 kg/mm2
      line: The CVD coating specification gives 1790 kg/mm2 for a TaC coating. No bulk hardness was read in this run.
    - label: Heat conduction
      benchmark: thermal_conductivity
      value: 22 W/mK
      line: The CVD coating specification gives 22 W/mK for a TaC coating. No bulk value was read in this run.
  compare: 'Tantalum carbide is a very high melting point ceramic with a high density. Its limit in air is oxidation: the CVD specification gives 700 degC for TaC, and it gives 850 degC for niobium metal. The sources read here do not give a bulk elastic modulus.'
  compare_rows:
    - label: Density
      benchmark: density
    - label: Hardness
      benchmark: hardness
    - label: Thermal conductivity
      benchmark: thermal_conductivity
  handling:
    - Keep the powder away from heat, sparks and open flames, and protect it from electrostatic charges (SDS P210 and Section 7).
    - Store it in a cool, dry place in tightly closed containers, away from oxidizing agents (SDS Section 7).
  good_for:
    - Very high melting point. The SDS gives 3880 degC.
    - Hard wear surfaces. The CVD specification gives 1790 kg/mm2 for a TaC coating, and TaC is used to coat steel moulds and sharp instruments.
  watch_out:
    - 'Oxidation in air: the CVD specification gives 700 degC as the oxidation temperature for a TaC coating.'
    - 'Sources disagree on the melting point: 3880 degC (SDS) and 3768 degC (Wikipedia, citing newer tests).'
    - Coating values (hardness, thermal conductivity, resistivity, expansion) are not bulk values. No bulk values for those were read in this run.
    - The powder is a flammable solid (H228) in the supplier SDS.
  verdict: Tantalum carbide is a very hard, very high melting point ceramic. The sourced uses are cutting tools and coatings, and hypersonic flight is a laboratory candidate, not a flight record. Its limits are oxidation in air above about 700 degC for coatings, the instability of the protective oxide melt at about 3000 degC, and a flammable powder.