spore: profile
id: rhenium
spore_version: 0.2
family: refractory-metals
name: Rhenium
abbreviation: Re
role: high-temperature structural metal for thruster chambers and superalloys
category: metals
type: refractory-metals
summary: |
  Rhenium is the element Re, a pure refractory metal with a density of 21.02 g/cm3 and a melting point of 3186 °C. Its main use is as an alloying addition to nickel-base superalloys for jet-engine turbine parts (about 80 % of end use in 2025, per USGS). It is also the structural substrate of iridium-coated rhenium rocket thrust chambers that NASA-funded tests ran at about 2200 °C with a specific impulse of 310 s for a 22 N class thruster. Uncoated rhenium oxidises in air above about 300 °C, so the flight-tested chambers depend on an iridium coating.
best_for: 'Structures that must hold strength above 2000 °C: iridium-coated rhenium thrust chambers tested up to about 2200 °C'
weakest_at: Oxidation in air or oxygen-rich gas above about 300 °C, which makes uncoated rhenium unusable without a protective coating
identity:
  formula: Re (element, atomic number 75); commercial grade 99.99 % (4N) rhenium, Goodfellow
  cas: 7440-15-5
  source: pubchem-re
  where: 'PubChem compound record for rhenium (CID 23947), Names and Identifiers section: CAS 7440-15-5; EC number 231-124-5 in the same record.'
  designations: []
tags:
  environments: []
  stresses: []
  applications:
    - propulsion-and-tanks
properties:
  - benchmark: density
    label: Density at 20 °C
    value: 21.02
    unit: g/cm3
    scope: material
    conditions:
      form: pure rhenium metal
      temperature: 20 °C
    method: Value printed on a supplier product page
    status: ground
    source: goodfellow-re
    where: General properties table, row Density
  - benchmark: melting_point
    label: Melting point
    value: 3186
    unit: °C
    scope: material
    conditions:
      form: pure rhenium metal
      unit_in_source: 3,186 °C (3,459 K)
    method: Value printed on a supplier product page
    status: ground
    source: goodfellow-re
    where: General properties table, row Melting point
  - benchmark: melting_point
    label: Melting point (university database, kelvin as printed)
    value: 3459
    unit: K
    scope: material
    conditions:
      form: rhenium element
      unit_in_source: 3459 K (3186 °C, 5767 °F)
    method: Value printed in a university element database entry
    status: ground
    source: utu-re
    where: Numeric properties list, Melting point row
  - benchmark: boiling_point
    label: Boiling point
    value: 5596
    unit: °C
    scope: material
    conditions:
      form: pure rhenium metal
      unit_in_source: 5,596 °C (5,869 K)
    method: Value printed on a supplier product page
    status: ground
    source: goodfellow-re
    where: General properties table, row Boiling point
  - benchmark: thermal_conductivity
    label: Thermal conductivity at 25 °C
    value: 48
    unit: W/m·K
    scope: material
    conditions:
      form: pure rhenium metal
      temperature: 25 °C
    method: Value printed on a supplier product page
    status: ground
    source: goodfellow-re
    where: General properties table, row Thermal conductivity
  - benchmark: electrical_resistivity
    label: Electrical resistivity at 20 °C
    value: 196
    unit: nΩ·m
    scope: material
    conditions:
      form: pure rhenium metal
      temperature: 20 °C
    method: Value printed on a supplier product page
    status: ground
    source: goodfellow-re
    where: General properties table, row Electrical resistivity
  - benchmark: elastic_modulus
    label: Young's modulus
    value: 460
    unit: GPa
    scope: material
    conditions:
      form: rhenium metal
      note_in_source: some sources list 360 to 460 GPa depending on crystallographic orientation
    method: Value printed on a supplier product page
    status: ground
    source: goodfellow-re
    where: Mechanical properties table, row Young's modulus
  - benchmark: poissons_ratio
    label: Poisson's ratio
    value: 0.3
    unit: '-'
    scope: material
    conditions:
      form: rhenium metal
    method: Value printed on a supplier product page
    status: ground
    source: goodfellow-re
    where: Mechanical properties table, row Poisson's ratio
  - benchmark: vickers_hardness
    label: Vickers hardness, annealed (custom name, not in property canon)
    value: 2450
    unit: MPa
    scope: material
    conditions:
      form: annealed rhenium
      approximate_in_source: printed as about 2,450 MPa Vickers
    method: Value printed on a supplier product page; the page also gives Mohs hardness of about 7
    status: ground
    source: goodfellow-re
    where: Mechanical properties table, row Hardness
  - benchmark: yield_strength
    label: Yield strength, annealed to cold-worked
    value: 200
    value_high: 500
    bound: range
    unit: MPa
    scope: material
    conditions:
      form: rhenium metal
      temper: annealed to cold-worked
    method: Range printed on a supplier product page
    status: ground
    source: goodfellow-re
    where: Mechanical properties table, row Yield strength
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, annealed to cold-worked
    value: 400
    value_high: 700
    bound: range
    unit: MPa
    scope: material
    conditions:
      form: rhenium metal
      temper: annealed to cold-worked
    method: Range printed on a supplier product page
    status: ground
    source: goodfellow-re
    where: Mechanical properties table, row Tensile strength
  - benchmark: elongation
    label: Elongation at break, annealed
    value: 30
    value_high: 50
    bound: range
    unit: '%'
    scope: material
    conditions:
      form: rhenium metal
      temper: annealed
    method: Range printed on a supplier product page
    status: ground
    source: goodfellow-re
    where: Mechanical properties table, row Elongation at break
  - benchmark: ultimate_tensile_strength
    label: Tensile strength at 1000 °C (approximate)
    value: 300
    unit: MPa
    scope: material
    conditions:
      form: rhenium metal
      temperature: 1000 °C
      note_in_source: printed as about 300 MPa at 1,000 °C
    method: Approximate value printed in the tensile-at-temperature note on a supplier product page
    status: ground
    source: goodfellow-re
    where: Property notes, tensile strength at temperature (about 300 MPa at 1,000 °C)
  - benchmark: vapor_pressure
    label: Vapour pressure at 2000 °C (custom name, not in property canon)
    value: 1.e-7
    unit: Pa
    scope: material
    conditions:
      form: rhenium metal
      temperature: 2000 °C
      note_in_source: printed as about 10^-7 Pa
    method: Approximate value printed on a supplier product page
    status: ground
    source: goodfellow-re
    where: Property notes, vapour pressure at 2,000 °C
  - benchmark: max_service_temp
    label: Thrust chamber wall temperature with iridium-coated rhenium, NASA-funded thruster
    value: 2200
    unit: °C
    scope: material
    conditions:
      system: iridium-coated rhenium thrust chamber
      test: hot-fire and life tests, NTO/MMH and oxygen/hydrogen propellants
      unit_in_source: 2200° C
    method: Value stated as the operating temperature the material allows in a NASA technical memorandum abstract
    status: ground
    source: nasa-tm-105348
    where: Abstract, sentence beginning "This material increases the operating temperature of thrusters"
  - benchmark: specific_impulse
    label: Specific impulse of 22 N NTO/MMH thruster with iridium-lined rhenium chamber (custom name, not in property canon)
    value: 310
    unit: s
    scope: material
    conditions:
      system: 22 N (5 lbf) class bipropellant thruster, 150:1 area ratio nozzle
      propellant: NTO/MMH
      test: hot-fire test, ground
    method: Measured value printed in a NASA contract final report abstract
    status: ground
    source: nasa-cr-185233
    where: Abstract, sentence "A specific impulse of 310 seconds was measured"
  - benchmark: specific_impulse_gain
    label: Specific impulse gain over silicide-coated niobium chambers (custom name, not in property canon)
    value: 20
    value_high: 25
    bound: range
    unit: s
    scope: material
    conditions:
      system: 22 N class thrusters, iridium-coated rhenium against niobium chambers
      test: steady-state firing, ground
    method: Range printed in a NASA technical memorandum abstract
    status: ground
    source: nasa-tm-105348
    where: Abstract, sentence "Stationkeeping class 22 N engines ... 20 to 25 seconds higher than niobium"
corrosion:
  - environment: Air or oxygen-containing gas above about 300 °C
    headline: Uncoated rhenium oxidises to a volatile oxide above about 300 °C, so it needs a protective coating in hot oxygen.
    effect: Goodfellow says rhenium forms volatile Re2O7 above about 300 °C in air. This is why the NASA thrusters use an iridium coating.
    rating: severe
    conditions:
      form: pure rhenium metal
      temperature: above about 300 °C
      atmosphere: air
    source: goodfellow-re
    where: Chemical and oxidation property notes, high-temperature oxidation entry
  - environment: NTO/MMH rocket combustion gas at 2100 to 2200 °C
    headline: An iridium coating protects rhenium chambers from hot NTO/MMH combustion gas for at least 15 hours.
    effect: Ultramet's report states that iridium protects rhenium from NTO/MMH combustion gases at 2100 to 2200 °C (3800 to 4000 °F) for at least 15 hours. One iridium-lined rhenium nozzle survived over 4000 cycles and 15 hours of continuous operation with no measurable change in throat dimensions.
    rating: moderate
    conditions:
      coating: iridium on rhenium, CVD
      environment: NTO/MMH combustion gas, 22 N thrusters
      duration: at least 15 hours
    source: nasa-tm-101309
    where: Concluding remarks; text on the 22 N thruster hot-fire tests
  - environment: Iridium-coated rhenium at high temperature in vacuum or oxygen
    headline: Rhenium diffuses into the iridium coating, which will eventually lead to coating failure.
    effect: 'NASA contract report: diffusion of rhenium into iridium will eventually lead to coating failure and subsequent exposure. Above 20 atomic percent rhenium the iridium-rhenium alloy readily oxidised in every environment tested.'
    rating: moderate
    conditions:
      test: diffusion couples held at 4000 °F (2200 °C) in vacuum, and oxidation tests of Ir-Re alloys
      note: from the NASA Phase II study
    source: nasa-cr-185233
    where: Results text on Ir/Re diffusion couples and Ir-Re alloy oxidation (Figure 3 discussion)
risks:
  hazards:
    - text: 'PubChem, from the ECHA C&L Inventory: of 393 company reports, 137 said rhenium does not meet GHS criteria and 256 gave hazard codes. Where codes were given, H228 flammable solid was reported in 63.9 %. Signal word Danger. Precautionary codes printed: P210, P240, P241, P280, P370+P378.'
      ghs:
        - H228
      source: pubchem-re
      where: GHS Classification section, notifications summary and hazard codes
    - text: 'PubChem hazards summary: the powdered form is flammable. It also notes no reported toxicity in workers handling perrhenic acid or ammonium perrhenate, citing Hawley and Ullmann.'
      ghs: []
      source: pubchem-re
      where: Other Safety Information, Hazards Summary entry
    - text: The Goodfellow product page prints UN number UN3089 for the metal powder form of rhenium.
      ghs: []
      source: goodfellow-re
      where: Identifiers and designation codes section, UN number entry
  failure_risks:
    - mode: Oxidation of uncoated rhenium in hot air or oxygen
      trigger: Uncoated rhenium exposed to air above about 300 °C
      consequence: Volatile Re2O7 forms, so the metal is lost from the surface. Goodfellow gives no rate.
      severity: high
      source: goodfellow-re
      where: Chemical and oxidation property notes, high-temperature oxidation entry
    - mode: Interdiffusion of rhenium into an iridium coating
      trigger: Iridium-coated rhenium held at high temperature for a long time
      consequence: The NASA contract report says the diffusion will eventually lead to coating failure and exposure of the rhenium to combustion gas.
      severity: moderate
      source: nasa-cr-185233
      where: Results text on Ir/Re diffusion couples
    - mode: Oxidation of iridium-rhenium alloys with high rhenium content
      trigger: Rhenium above 20 atomic percent in an iridium-rhenium alloy
      consequence: The alloy readily oxidised in all environments tested, so the coating must stay near pure iridium.
      severity: moderate
      source: nasa-cr-185233
      where: Results text, Figure 3 discussion of Ir/Re oxidation rate
  side_effects:
    - text: The USGS gives a 2025 estimated average price of 2,600 US dollars per kilogram for rhenium metal at 99.99 % purity, a 90 % rise on 2024. Industry sources said recyclers need prices above 3,000 dollars per kilogram to offset processing costs.
      affects: Cost of components and of recycling superalloy scrap
      source: usgs-mcs2026-rhenium
      where: Salient Statistics, price row Metal, 99.99% pure; Events, Trends, and Issues
  handling:
    - text: Goodfellow says rhenium requires diamond or CBN grinding wheels for machining.
      source: goodfellow-re
      where: Hardness property note
    - text: The metal powder is flammable (H228 in PubChem). The safety codes are listed in the PubChem record. Handle as a flammable solid in powder form.
      source: pubchem-re
      where: GHS Classification section
  mitigations:
    - text: NASA thrusters use an iridium coating, applied by CVD over a rhenium substrate, to resist oxidation in the combustion gas.
      source: nasa-tm-101309
      where: Introduction, paragraph on what rhenium lacks and the iridium coating
uses:
  - application: propulsion-and-tanks
    device: Iridium-lined rhenium thrust chamber for a 22 N (5 lbf) bipropellant thruster
    example: A 22 N class NTO/MMH thruster with an iridium-lined rhenium chamber and a 150:1 nozzle reached 310 s specific impulse in a hot-fire test. NASA lists these 22 N chambers for orbit insertion, stationkeeping or attitude control.
    source: nasa-cr-185233
    where: Abstract (310 s); see nasa-tm-101309 Introduction for the list of spacecraft functions
  - application: propulsion-and-tanks
    device: Nickel-base superalloy parts for high-temperature turbine engine components
    example: USGS estimates superalloys took about 80 % of rhenium end use in 2025. Rhenium improves the high-temperature (above 1000 °C) strength of some nickel-base superalloys.
    source: usgs-mcs2026-rhenium
    where: Domestic Production and Use paragraph, first sentences
  - application: electronics-and-chips
    device: Electrical contacts, thermocouples and electron tubes
    example: USGS lists rhenium alloys among uses in electrical contacts, electron tubes and targets, thermocouples, semiconductors and vacuum tubes. Tungsten-rhenium thermocouples are not sourced here.
    source: usgs-mcs2026-rhenium
    where: Domestic Production and Use paragraph, list of other applications
supply:
  - subject: Rhenium (mine production, rhenium content, 2025)
    producers:
      - country: Chile
        share_percent: 37
        year: 2025
      - country: China
        share_percent: 24.7
        year: 2025
      - country: Poland
        share_percent: 12.3
        year: 2025
      - country: United States
        share_percent: 12.1
        year: 2025
      - country: Uzbekistan
        share_percent: 8.6
        year: 2025
    critical_lists:
      - list: U.S. Final 2025 List of Critical Minerals (rhenium added; USGS Mineral Commodity Summaries 2026)
        listed: true
    recycling: 'USGS: nickel-base superalloy scrap and scrapped turbine blades are recycled hydrometallurgically to make rhenium metal for new superalloy melts. Industry sources estimate global secondary production at 20,000 to 25,000 kg in 2025, excluding rhenium recovered in a closed loop from spent catalysts.'
    substitutes:
      - 'USGS: iridium and tin catalysts have been commercially successful in place of platinum-rhenium; cobalt and tungsten for coatings on copper X-ray targets; rhodium and rhodium-iridium for high-temperature thermocouples; tungsten and platinum-ruthenium for electrical contacts; tungsten and tantalum for electron emitters.'
    source: usgs-mcs2026-rhenium
    where: World Mine Production and Reserves table, 2025 column (world total 81,000 kg; shares calculated by Space Mushroom from Chile 30,000, China 20,000, Poland 10,000, United States 9,800, Uzbekistan 7,000 kg); Recycling; Substitutes; Events, Trends, and Issues
  - subject: Rhenium imports to the United States (rhenium metal, 2021 to 2024)
    producers:
      - country: Chile
        share_percent: 38
        year: 2024
      - country: Canada
        share_percent: 28
        year: 2024
      - country: Germany
        share_percent: 21
        year: 2024
      - country: Poland
        share_percent: 11
        year: 2024
    critical_lists: []
    recycling: 'USGS: United States imports for consumption of unwrought rhenium and powders were 23,000 kg in 2025e, against 12,600 kg in 2024. Net import reliance was 75 % of apparent consumption in 2025e.'
    substitutes: []
    source: usgs-mcs2026-rhenium
    where: Import Sources (2021-24) paragraph, rhenium metal list; Salient Statistics, Imports for consumption row
documents:
  - title: Goodfellow Metals, Rhenium (Re 99.99 %) product information page
    type: datasheet
    url: https://www.goodfellow.com/usa/material/metals/rhenium
  - title: University of Turku, Institute of Organic Chemistry and Element Database, Rhenium element page
    type: database
    url: https://imc.utu.fi/elements/rhenium.php
  - title: 'USGS Mineral Commodity Summaries 2026: Rhenium'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-rhenium.pdf
    year: 2026
  - title: PubChem compound record for rhenium (CID 23947), including ECHA C&L Inventory classification
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/Rhenium
  - title: 'Aerojet, Contract NAS 3-24643 Final Report: High-Temperature, Oxidation-Resistant Thruster Research, NASA CR 185233'
    type: report
    url: https://ntrs.nasa.gov/api/citations/19910006750/downloads/19910006750.pdf
    year: 1990
  - title: Schneider, High Temperature Thruster Technology for Spacecraft Propulsion, NASA TM 105348 (IAF-91-254)
    type: paper
    url: https://ntrs.nasa.gov/api/citations/19920005907/downloads/19920005907.pdf
    year: 1991
  - title: Harding and Kazaroff, Iridium-Coated Rhenium Thrusters by CVD, NASA TM 101309
    type: paper
    url: https://ntrs.nasa.gov/api/citations/19880020490/downloads/19880020490.pdf
    year: 1988
  - title: 'Wikipedia: Rhenium (composition, history and production method only)'
    type: database
    url: https://en.wikipedia.org/wiki/Rhenium
gaps:
  - 'Designations: no UNS, ASTM, AISI, EN, DIN, JIS or trade-name code for pure rhenium was printed in any source fetched in this run. MatWeb''s search returned no rhenium datasheet, the Rembar page returned 404, and the Plansee datasheet found covers only Mo-Re alloys. identity.designations is left empty.'
  - Coefficient of thermal expansion for pure rhenium was not found in a fetched page with a value; the Goodfellow page prints none and the Wikipedia figure was not used under the composition-only rule.
  - 'Specific heat, heat of fusion and heat of vaporisation: not found in a fetched source with a condition.'
  - 'Electrical conductivity in % IACS and a room-temperature resistivity from a second source: not found.'
  - Radiation effects, cold welding and atomic-oxygen erosion of rhenium were not looked up.
  - 'Corrosion rate in numbers (mass loss per hour in air or NTO/MMH gas): NASA reports give qualitative results and a 0.05 mil/h figure for pure iridium, not rhenium; no rhenium rate was recorded.'
  - The Plansee rhenium data sheet and the NIMS material data page were not reachable (404); the Rembar rhenium page was also not reachable (404).
  - Thruster and coating values come from NASA contract reports and technical memoranda of 1988 to 1991 (ground tests); no flight result for an iridium-coated rhenium chamber was found.
  - Tensile strength at 1000 °C, 1500 °C and 2500 °C is printed only as approximate values on the Goodfellow page; they are recorded at 1000 °C only.
  - Vickers hardness, vapour pressure, specific impulse and specific impulse gain use custom property names because no canonical name exists for them in spores/property-canon.yaml.
  - Supply shares are calculated by Space Mushroom from USGS tonnages (kg of rhenium content) and rounded to one decimal place.
  - USGS 2025 mine production for Chile is an estimate from roaster residues (footnote 9); the value is printed as 30,000 kg.
  - Rhenium ores and by-product recovery (roasting molybdenum concentrates) are described from the USGS text only; no smelting-process detail beyond the Wikipedia production method was read.
sources:
  goodfellow-re:
    title: Goodfellow Metals, Rhenium Re 99.99 % (4N), product information page
    url: https://www.goodfellow.com/usa/material/metals/rhenium
    kind: datasheet
    license: Supplier product page (cited, not reproduced)
  utu-re:
    title: University of Turku, element database entry for rhenium
    url: https://imc.utu.fi/elements/rhenium.php
    kind: database
    license: University web page (cited, not reproduced)
  usgs-mcs2026-rhenium:
    title: Mineral Commodity Summaries 2026, Rhenium (U.S. Geological Survey, February 2026)
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-rhenium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  pubchem-re:
    title: 'PubChem compound record: Rhenium (CID 23947), including ECHA C&L Inventory classification'
    id: CAS 7440-15-5, EC 231-124-5
    url: https://pubchem.ncbi.nlm.nih.gov/compound/Rhenium
    kind: database
    license: PubChem (NCBI), public domain; sections attributed to ECHA and others
  nasa-cr-185233:
    title: Aerojet, High-Temperature, Oxidation-Resistant Thruster Research, final report on NASA contract NAS 3-24643 (NASA CR 185233, February 1990)
    id: NTRS 19910006750
    url: https://ntrs.nasa.gov/api/citations/19910006750/downloads/19910006750.pdf
    year: 1990
    kind: report
    license: public domain (NASA)
  nasa-tm-105348:
    title: Schneider, High Temperature Thruster Technology for Spacecraft Propulsion (NASA TM 105348, IAF-91-254)
    id: NTRS 19920005907
    url: https://ntrs.nasa.gov/api/citations/19920005907/downloads/19920005907.pdf
    year: 1991
    kind: paper
    license: public domain (NASA)
  nasa-tm-101309:
    title: Harding and Kazaroff, Iridium-Coated Rhenium Thrusters by CVD (NASA TM 101309)
    id: NTRS 19880020490
    url: https://ntrs.nasa.gov/api/citations/19880020490/downloads/19880020490.pdf
    year: 1988
    kind: paper
    license: public domain (NASA)
  wikipedia-re:
    title: Rhenium (Wikipedia; composition, history and production method only)
    url: https://en.wikipedia.org/wiki/Rhenium
    kind: web
    license: CC BY-SA 4.0 (cited, not reproduced)
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 17
  unreachable: 2
  caveats: 6
  note: 'Values were read by an AI assistant on 2026-10-26 from the pages and PDFs named in each entry. Unreachable: NIMS and Rembar rhenium pages (HTTP 404). Caveats: the 2200 °C and 310 s values come from NASA ground-test reports; Young''s modulus has a published range; the tensile values are ranges across temper; the hardness and vapour pressure are approximate; supply shares are calculated.'
story:
  risk_groups:
    - title: For people
      lead: The opened sources do not describe health effects of rhenium metal. The hazard entries are about the powder and a notification record.
      level: 1
      verdict: Powder is flammable
      points:
        - label: Rhenium as a substance
          line: PubChem lists rhenium as a flammable solid (H228) with the signal word Danger in 63.9 % of the reports that gave codes. Of 393 reports, 137 said it does not meet GHS criteria.
        - label: Powder
          line: PubChem says the powdered form is flammable and that no toxicity has been reported in workers handling perrhenic acid or ammonium perrhenate.
    - title: If it fails
      lead: The failure routes come from NASA ground tests and from the handbook-style property notes, not from flight data.
      points:
        - label: Hot air
          line: Uncoated rhenium forms volatile Re2O7 above about 300 °C in air, so it must be coated for hot oxygen service.
        - label: Coating
          line: NASA reports that rhenium diffuses into the iridium coating, which will eventually cause coating failure.
    - title: Handling and storage
      points:
        - label: Machining
          line: Goodfellow says rhenium needs diamond or CBN grinding wheels. Keep powder away from ignition sources as the PubChem codes advise.
  why: 'Rhenium is a dense, very high-melting metal: 21.02 g/cm3 and 3186 °C. Its value comes from strength at high temperature. Alloyed into nickel-base superalloys it raises the strength of turbine parts above 1000 °C, and USGS puts that use at about 80 % of 2025 end use. It also forms the structural wall of thrust chambers that NASA-funded tests ran at about 2200 °C. Pure rhenium oxidises in air above about 300 °C, so the flight-candidate chambers carry an iridium coating.'
  uses:
    - where: Jet-engine superalloys
      line: Rhenium improves the high-temperature strength of some nickel-base superalloys used in turbine engine parts. USGS estimates superalloys took about 80 % of end use in 2025.
    - where: Thruster chambers
      line: A 22 N class NTO/MMH thruster with an iridium-lined rhenium chamber reached 310 s specific impulse in a hot-fire test. NASA lists these chambers for orbit insertion, stationkeeping and attitude control.
    - where: Electrical and thermal parts
      line: USGS lists rhenium alloys in electrical contacts, electron tubes, thermocouples and vacuum tubes. Platinum-rhenium catalysts are a further use, about 15 % of 2025 end use.
  can_do:
    - label: Stay strong when hot
      value: 300 MPa at 1000 °C
      benchmark: ultimate_tensile_strength
      line: Goodfellow gives an approximate tensile strength of 300 MPa at 1000 °C, about 150 MPa at 1500 °C and about 50 MPa at 2500 °C.
    - label: Run hot
      value: 2200 °C
      benchmark: max_service_temp
      line: NASA reports that the iridium-coated rhenium chamber allows thruster operation up to 2200 °C.
    - label: Heavy metal
      value: 21.02 g/cm3
      benchmark: density
      line: Density is 21.02 g/cm3 at 20 °C, and the metal is hard, with a Vickers hardness of about 2450 MPa when annealed (Goodfellow).
    - label: Melting
      value: 3186 °C
      benchmark: melting_point
      line: The melting point is 3186 °C (3459 K) in both the supplier page and the University of Turku database.
    - label: Thrust gain
      value: 20 to 25 s
      benchmark: specific_impulse_gain
      line: Steady-state firing of the iridium-coated rhenium 22 N engines gave 20 to 25 s higher specific impulse than niobium chambers.
  compare: 'Against silicide-coated niobium thrust chambers, the baseline in the NASA reports, iridium-coated rhenium is rated to 2200 °C and gives 20 to 25 s more specific impulse. Rhenium is also costly: USGS gives 2,600 US dollars per kilogram for 99.99 % metal in 2025.'
  compare_rows:
    - label: Density
      benchmark: density
    - label: Melting point
      benchmark: melting_point
    - label: Thrust chamber max temperature
      benchmark: max_service_temp
  handling:
    - Use diamond or CBN wheels to machine it, as Goodfellow advises.
    - Keep powder away from ignition sources, since the PubChem record gives it as a flammable solid.
    - Specify the coating for hot oxygen service; uncoated rhenium oxidises above about 300 °C.
  good_for:
    - Strength above 2000 °C in thrust chambers, tested to 2200 °C with an iridium coating.
    - Superalloy additions that raise high-temperature strength; superalloys took about 80 % of 2025 end use.
    - 'Recycling: superalloy scrap and spent catalysts are recovered in a closed loop.'
  watch_out:
    - 'Oxidation: uncoated rhenium loses material as volatile Re2O7 above about 300 °C in air.'
    - 'Coating life: rhenium diffuses into iridium and eventually causes coating failure, per NASA.'
    - 'Supply: the United States imported about 75 % of its apparent consumption in 2025e, and rhenium was added to the 2025 critical minerals list.'
    - 'Cost: 2,600 US dollars per kilogram for metal in 2025, up 90 % on 2024.'
    - No flight result for an iridium-coated rhenium chamber, no thermal expansion value and no radiation data were found for this profile.
  verdict: Rhenium is a dense, high-melting metal (21.02 g/cm3, 3186 °C) that keeps strength above 2000 °C, which is why it is used in superalloys and in iridium-coated rhenium thrust chambers tested to about 2200 °C. Uncoated, it oxidises above about 300 °C, the iridium coating wears by interdiffusion over time, and the metal is costly. The profile has no UNS designation and no thermal expansion value from a fetched source.
  recipe:
    line: Rhenium is a single-element metal (Re, atomic number 75) (PubChem; Wikipedia). It is mostly recovered as a by-product of roasting molybdenum concentrates from porphyry copper-molybdenum deposits (USGS). Wikipedia states that the metal is made by reducing ammonium perrhenate with hydrogen at high temperature.
    parts:
      - name: Rhenium
        symbol: Re
        atoms: 1
        atomic_weight: 186.207
        role: The whole material. PubChem prints the molecular weight of the element as 186.207.