Tungsten-copper W-Cu

spore: profile
id: tungsten-copper
spore_version: 0.2
family: refractory-metals
name: Tungsten-copper
abbreviation: W-Cu
role: heat sink and electrical contact composite
category: metals
type: refractory-metals
summary: |
  Tungsten-copper (W-Cu, also written CuW or WCu) is a metal matrix composite, not an alloy: a sintered tungsten skeleton is infiltrated with molten copper, and common grades hold 10 to 40 wt % copper. The grade W80Cu20 (Plansee grade WCu20) has a density of 15.15 g/cm3 and an electrical conductivity of 34 %IACS in a supplier table. The Plansee typical thermal conductivity of WCu20 is 235 W/(m·K) at 20 °C, with a thermal expansion of 8.3 ppm/K. The copper phase melts at 1083 °C, and tungsten oxidises strongly in air from about 400 °C.
best_for: 'Heat sinks and electrical contacts: a thermal conductivity of 235 W/(m·K) at 20 °C with a low thermal expansion of 8.3 ppm/K in the Plansee WCu20 grade'
weakest_at: 'Heavy, and it oxidises in hot air: density 15.15 g/cm3 for W80Cu20, and strong oxidation in air beginning around 400 °C'
identity:
  formula: 'W-Cu composite: a tungsten (W) skeleton with copper (Cu) infiltrated, 10 to 40 wt % Cu (Plansee SDS, Section 3)'
  cas: 7440-33-7 (W); 7440-50-8 (Cu)
  source: plansee-wcu-sds
  where: 'Section 3 Composition, row Summary: tungsten and copper 10-40 % mass fraction, with CAS numbers for tungsten and copper'
  designations:
    - system: Trade name
      code: WCu20
      note: Plansee grade name for 80 % W, remainder Cu
      source: plansee-materials
      where: Materials table, row WCu20, column Chemical composition W 80, remainder Cu (Ni)
    - system: ASTM
      code: B702
      note: Class D, about 75 % W and 25 % Cu (W75Cu25)
      source: samaterials-cuw75
      where: Product title and specification line, ASTM B702, Grade Class D
tags:
  applications:
    - thermal-control
    - electronics-and-chips
    - propulsion-and-tanks
properties:
  - benchmark: density
    label: Density, W80Cu20 (tungsten.com composition table)
    value: 15.15
    unit: g/cm3
    scope: material
    conditions:
      grade: W80Cu20 (80 % W, 20 % Cu)
      temperature: not printed on the page
      unit_in_source: gr/cc
    method: Value printed in a supplier composition table
    status: ground
    source: tungsten-com
    where: Composition table, row W80 Cu20, column Density gr/cc
  - benchmark: density
    label: Density, W75Cu25 (tungsten.com composition table)
    value: 14.5
    unit: g/cm3
    scope: material
    conditions:
      grade: W75Cu25 (75 % W, 25 % Cu)
      temperature: not printed on the page
      unit_in_source: gr/cc
    method: Value printed in a supplier composition table
    status: ground
    source: tungsten-com
    where: Composition table, row W75 Cu25, column Density gr/cc
  - benchmark: density
    label: Density, WCu20 (Plansee typical, 80 % W)
    value: 15.5
    unit: g/cm3
    scope: material
    conditions:
      grade: WCu20 (80 % W, remainder Cu)
      temperature: 20 °C
    method: Typical value printed in a manufacturer properties table, stated as typical properties at 20 °C
    status: ground
    source: plansee-properties
    where: Typical properties of our WCu materials at 20 °C table, row WCu20, column Density [g/cm³]
  - benchmark: thermal_conductivity
    label: Thermal conductivity, WCu20 (Plansee typical, 80 % W)
    value: 235
    unit: W/(m·K)
    scope: material
    conditions:
      grade: WCu20 (80 % W, remainder Cu)
      temperature: 20 °C
    method: Typical value printed in a manufacturer properties table, stated as typical properties at 20 °C
    status: ground
    note: The same table gives 195 W/(m·K) for WCu10 and 215 W/(m·K) for WCu15, so conductivity rises as copper content rises.
    source: plansee-properties
    where: Typical properties of our WCu materials at 20 °C table, row WCu20, column TC [W/mK]
  - benchmark: thermal_conductivity
    label: Thermal conductivity, W80/20 (SVS)
    value: 180
    unit: W/(m·K)
    scope: material
    conditions:
      grade: WCu 80/20 (80 % W)
      temperature: 25 °C
      unit_in_source: W/(m·K)
    method: Value printed in a supplier property table; the page does not say whether the value is typical or minimum
    status: ground
    note: A second supplier prints 235 W/(m·K) for a W80 grade at 20 °C, so the sources differ by about 55 W/(m·K).
    source: svs-wcu
    where: Physical and Mechanical Properties table, row Thermal conductivity at 25 °C, column WCu 80/20
  - benchmark: cte
    label: Coefficient of thermal expansion, WCu20 (Plansee typical)
    value: 8.3
    unit: ppm/K
    scope: material
    conditions:
      grade: WCu20 (80 % W, remainder Cu)
      temperature: 20 °C
    method: Typical value printed in a manufacturer properties table
    status: ground
    source: plansee-properties
    where: Typical properties of our WCu materials at 20 °C table, row WCu20, column CTE [ppm/K]
  - benchmark: cte
    label: Coefficient of thermal expansion, W80/20 (SVS)
    value: 8.8
    unit: ppm/K
    scope: material
    conditions:
      grade: WCu 80/20 (80 % W)
      temperature: 20 °C to 300 °C
      unit_in_source: × 10⁻⁶/K⁻¹
    method: Value printed in a supplier property table; the page gives no test standard
    status: ground
    source: svs-wcu
    where: Physical and Mechanical Properties table, row Linear expansion coefficient (20 °C–300 °C), column WCu 80/20
  - benchmark: electrical_conductivity
    label: Electrical conductivity, W80Cu20 (tungsten.com)
    value: 34
    unit: '%IACS'
    scope: material
    conditions:
      grade: W80Cu20 (80 % W, 20 % Cu)
      temperature: not printed on the page
    method: Value printed in a supplier composition table, given as % IACS
    status: ground
    source: tungsten-com
    where: Composition table, row W80 Cu20, column IACS %
  - benchmark: electrical_conductivity
    label: Electrical conductivity, W75Cu25 (tungsten.com)
    value: 38
    unit: '%IACS'
    scope: material
    conditions:
      grade: W75Cu25 (75 % W, 25 % Cu)
      temperature: not printed on the page
    method: Value printed in a supplier composition table, given as % IACS
    status: ground
    source: tungsten-com
    where: Composition table, row W75 Cu25, column IACS %
  - benchmark: electrical_conductivity
    label: Electrical conductivity, W80/20 (SVS range)
    value: 38
    value_high: 45
    bound: range
    unit: '%IACS'
    scope: material
    conditions:
      grade: WCu 80/20 (80 % W)
      temperature: not printed on the page
    method: Range printed in a supplier property table; the page does not say whether it is minimum, typical or tolerance
    status: ground
    source: svs-wcu
    where: Physical and Mechanical Properties table, row Electrical conductivity % IACS, column WCu 80/20
  - benchmark: electrical_resistivity
    label: Electrical resistivity, W80/Cu20 (Torrey Hills)
    value: 5
    unit: µΩ·cm
    scope: material
    conditions:
      grade: W80/Cu20 (80 % W, 20 % Cu)
      temperature: not printed on the page
      unit_in_source: µΩ.cm
    method: Value printed in a supplier property table
    status: ground
    source: torrey-cuw
    where: Copper tungsten property table, row W80/Cu20, column Resistivity (µΩ.cm)
  - benchmark: hardness
    label: Hardness, W80Cu20 (tungsten.com)
    value: 220
    unit: HB Kgf/mm2
    scope: material
    conditions:
      grade: W80Cu20 (80 % W, 20 % Cu)
      temperature: not printed on the page
      unit_in_source: HB Kgf/mm2
    method: Value printed in a supplier composition table
    status: ground
    note: Torrey Hills prints the same 220 for W80/Cu20 in its table, so the hardness is the same in both supplier tables.
    source: tungsten-com
    where: Composition table, row W80 Cu20, column Hardness HB Kgf/mm2
  - benchmark: flexural_strength
    label: Bending strength, W80Cu20 (tungsten.com)
    value: 736
    unit: MPa
    scope: material
    conditions:
      grade: W80Cu20 (80 % W, 20 % Cu)
      temperature: not printed on the page
    method: Value printed in a supplier composition table
    status: ground
    note: Torrey Hills prints 980 MPa for the same grade in its own table, so suppliers differ by about 240 MPa on bending strength.
    source: tungsten-com
    where: Composition table, row W80 Cu20, column Bend Strength MPa
  - benchmark: flexural_strength
    label: Bending strength, W80/Cu20 (Torrey Hills)
    value: 980
    unit: MPa
    scope: material
    conditions:
      grade: W80/Cu20 (80 % W, 20 % Cu)
      temperature: not printed on the page
    method: Value printed in a supplier property table
    status: ground
    note: Tungsten.com prints 736 MPa for W80 Cu20 in its own table.
    source: torrey-cuw
    where: Copper tungsten property table, row W80/Cu20, column Bending Strength (Mpa)
  - benchmark: ultimate_tensile_strength
    label: Tensile strength Rm, W80/20 (SVS)
    value: 620
    value_high: 689
    bound: range
    unit: MPa
    scope: material
    conditions:
      grade: WCu 80/20 (80 % W)
      temperature: not printed on the page
      form: not stated
    method: Range printed in a supplier property table; the page does not say whether the figures are minimum, typical or tolerance
    status: ground
    source: svs-wcu
    where: Physical and Mechanical Properties table, row Tensile strength (Rm), column WCu 80/20
  - benchmark: elongation
    label: Elongation at 20 °C, W80/20 (SVS)
    value: 8.3
    unit: '%'
    scope: material
    conditions:
      grade: WCu 80/20 (80 % W)
      temperature: 20 °C
    method: Value printed in a supplier property table
    status: ground
    source: svs-wcu
    where: Physical and Mechanical Properties table, row Elongation at 20 °C, column WCu 80/20
  - benchmark: elastic_modulus
    label: E-module, W80/20 (SVS)
    value: 280
    unit: GPa
    scope: material
    conditions:
      grade: WCu 80/20 (80 % W)
      temperature: not printed on the page
    method: Value printed in a supplier property table
    status: ground
    source: svs-wcu
    where: Physical and Mechanical Properties table, row E-module, column WCu 80/20
corrosion:
  - environment: Air at high temperature
    headline: Tungsten oxidises strongly in air from about 400 °C, and its oxide WO3 sublimes from about 850 °C.
    effect: 'The Plansee SDS lists high temperatures in air as the condition to avoid: strong oxidation beginning around 400 °C, and sublimation of WO3 beginning around 850 °C. The SDS gives no oxidation rate.'
    rating: moderate
    conditions:
      basis: product data sheet statement, no test condition or rate given
      product: W-Cu composite
    source: plansee-wcu-sds
    where: Section 10 Stability and reactivity, conditions to be avoided
  - environment: Water, acids and bases
    headline: W-Cu is insoluble in water, acids and bases, and dissolves only in hydrofluoric acid or in a base with a strong oxidising agent.
    effect: The Plansee SDS prints these solubility statements for the composite. No corrosion rate is given.
    rating: low
    conditions:
      basis: product data sheet statement, no test condition given
    source: plansee-wcu-sds
    where: Section 9 Physical and chemical properties, row Solubility
risks:
  hazards:
    - text: Plansee's REACH product data sheet classes the material as not hazardous under Regulation (EC) No 1272/2008, and calls it a compact metal or alloy with no risk to human health or the environment.
      ghs: []
      source: plansee-wcu-sds
      where: Section 2 Hazards identification
    - text: Dust formation gives an increased fire hazard, and breathing protection is needed in the presence of dust. The product itself is not flammable.
      ghs: []
      source: plansee-wcu-sds
      where: Section 5 Fire-fighting measures
    - text: 'Workplace exposure thresholds printed in the SDS, under Austrian legal regulations: tungsten 5 mg/m3 inhalable fraction (mean daily value) and copper 1 mg/m3.'
      ghs: []
      source: plansee-wcu-sds
      where: Section 8 Exposure controls, Exposure thresholds, and Section 15 Regulatory information
  failure_risks:
    - mode: Oxidation in hot air
      trigger: Use in air at high temperature, from about 400 °C
      consequence: Strong oxidation of the tungsten begins around 400 °C, and WO3 sublimes from about 850 °C, so the surface is consumed in hot air. The source gives no rate.
      severity: moderate
      source: plansee-wcu-sds
      where: Section 10 Stability and reactivity
    - mode: Copper phase melts
      trigger: Temperature at or above the melting point of copper, 1083 °C (SDS) or about 1080 °C (US patent 5705283)
      consequence: The copper constituent is molten at this temperature, which is well below the tungsten melting point of 3410 °C. The sources give no measured effect on the composite.
      severity: moderate
      source: plansee-wcu-sds
      where: Section 9 Melting point row; US patent 5705283, background text
  side_effects:
    - text: Dust from machining or sublimate at high temperature is a workplace exposure, and suction cleaning is advised when processing at high temperatures.
      affects: Operators and workshop air
      source: plansee-wcu-sds
      where: Section 7 Handling and storage; Section 8 Workplace exposure
  handling:
    - text: Dust should be suction cleaned directly at source, and at least one FFP2 respirator is advised when working with dust.
      source: plansee-wcu-sds
      where: Section 6 Accidental release measures; Section 8 Workplace exposure
    - text: Avoid dust formation. Use suction cleaning if dust is unavoidable, and when processing at high temperatures because sublimate forms.
      source: plansee-wcu-sds
      where: Section 7 Handling and storage
  mitigations: []
uses:
  - application: thermal-control
    device: Heat sinks
    example: Plansee lists heat sinks, arcing contacts and electrodes among the products made from its WCu composite. The Plansee WCu20 grade has a thermal conductivity of 235 W/(m·K) at 20 °C.
    source: plansee-wcu-sds
    where: Section 1 Identification, Use of the substance; Plansee properties table, row WCu20
  - application: electronics-and-chips
    device: Chip carriers and substrates for power semiconductors
    example: Wikipedia says CuW75 is used as chip carriers and substrates for power semiconductors, with a thermal expansion matched to silicon and gallium arsenide.
    source: wikipedia-cuw
    where: Applications section
  - application: electronics-and-chips
    device: Arcing and electrical contacts
    example: Plansee lists arcing contacts among its W-Cu products, and Wikipedia lists electrical contacts and vacuum contacts among the uses of copper-tungsten.
    source: wikipedia-cuw
    where: Applications section; Plansee SDS Section 1 for arcing contacts
  - application: propulsion-and-tanks
    device: Rocket combustion chamber and nozzle walls, and throat inserts
    example: US patent 5705283 proposes that part or all of the combustion chamber and expansion nozzle be made of a tungsten-copper composite. A supplier page calls tungsten-copper the preferred material for modern rocket throat linings.
    source: us-patent-5705283
    where: Background section; refractorymetal-rocket article, first paragraphs
supply:
  - subject: Tungsten (world mine production, the tungsten content of W-Cu)
    producers:
      - country: China
        share_percent: 78.8
        year: 2025
      - country: Vietnam
        share_percent: 3.5
        year: 2025
      - country: Kazakhstan
        share_percent: 2.8
        year: 2025
      - country: Russia
        share_percent: 2.4
        year: 2025
    critical_lists: []
    recycling: 'USGS: the estimated quantity of secondary tungsten produced in 2025 is withheld to avoid disclosing company proprietary data. Net import reliance is more than 50 % of apparent consumption in 2021 to 2025e.'
    substitutes:
      - 'USGS: molybdenum for certain tungsten mill products, and depleted uranium or lead for tungsten or tungsten alloys in applications requiring high density or radiation shielding.'
    source: usgs-mcs2026-tungsten
    where: 'World Mine Production and Reserves table, mine production 2025: China 67,000; Vietnam 3,000; Kazakhstan 2,400; Russia 2,000; world total 85,000 t, tungsten content. Shares calculated by Space Mushroom from these values (67,000 / 85,000 = 78.8 %). Recycling, Substitutes and Salient Statistics sections.'
documents:
  - title: 'Plansee, Tungsten composites: typical properties of WCu materials at 20 °C'
    type: datasheet
    url: https://www.plansee.com/en/materials/tungsten-composites/properties.html
    year: 2026
  - title: 'Plansee, Tungsten composites: materials and grades (WCu10, WCu15, WCu20)'
    type: datasheet
    url: https://www.plansee.com/en/materials/tungsten-composites/materials.html
    year: 2026
  - title: Plansee, Product data sheet PDS-041, WCu-composite material (REACH), valid from 12 July 2022
    type: sds
    url: https://www.plansee.com/download/?DOKNR=PSE-030-PDS-041&DOKAR=QM1&DOKTL=100
    year: 2022
  - title: Torrey Hills Technologies, Properties of Copper Tungsten
    type: datasheet
    url: https://www.torreyhillstech.com/cuwdata.html
  - title: Tungsten.com, Tungsten Copper Alloy (W-Cu) material information
    type: datasheet
    url: https://www.tungsten.com/material-info/tungsten-copper-alloy-w-cu
  - title: SVS Schweisstechnik, Tungsten-Copper (WCu), refractory alloys
    type: datasheet
    url: https://www.svs-schweisstechnik.de/en/knowledge-hub/refractory-alloys/tungsten-copper-wcu/
  - title: SA Materials, Tungsten Copper Composite (W-Cu composite) CuW75, catalog WM7700
    type: datasheet
    url: https://www.samaterials.com/item/wm7700-tungsten-copper-composite-w-cu-composite-cuw75.html
  - title: 'Wikipedia: Copper-tungsten (CuW, WCu)'
    type: database
    url: https://en.wikipedia.org/wiki/Copper%E2%80%93tungsten
  - title: 'USGS Mineral Commodity Summaries 2026: Tungsten'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tungsten.pdf
    year: 2026
  - title: US Patent 5,705,283, Tungsten-copper composite material with rhenium protective layer, and its preparation
    type: report
    url: https://patents.google.com/patent/US5705283A/en
  - title: Refractory Metal, Tungsten Copper Alloy for Rocket Throat Lining
    type: datasheet
    url: https://www.refractorymetal.org/tungsten-copper-alloy-for-rocket-throat-lining.html
gaps:
  - 'Critical-mineral status: the USGS 2026 tungsten summary read here does not print a critical-minerals list entry, so critical_lists is empty.'
  - ASTM B702 class for W80Cu20 (grade E in one distributor listing) was not read on a fetched page, so only the W75Cu25 class (Class D, SA Materials) is recorded as a designation.
  - No UNS, EN, DIN, JIS or W.Nr. number for copper-tungsten was found on a page read in this run. The Plansee and SVS pages print only their own grade labels.
  - The Plansee SDS gives a density range of 13 to 18.3 g/cm3 for the whole composite family; it is not a grade value and is not recorded.
  - The 400 °C and 850 °C oxidation figures are printed as approximate ('beginning around'), and no oxidation rate or mass loss in air was found.
  - No outgassing, total mass loss, atomic-oxygen erosion or cold-welding result for W-Cu in vacuum or low Earth orbit was found in a readable source.
  - No spacecraft-specific flight use of W-Cu was found. The rocket evidence is for combustion chamber and nozzle parts (US patent 5705283, supplier article). The patent's link to small station-keeping thrusters is an inference and is not recorded.
  - Electrical resistivity and IACS for W75Cu25 were not recorded as separate values from a second supplier; tungsten.com and Torrey Hills both print them for W75Cu25 but were not included to keep one value per grade.
  - Tensile and elongation values from SVS have no temper or form stated, and the page does not say whether they are minimum, typical or tolerance values.
  - Process steps are from Wikipedia (pressing, sintering, infiltration) and the patent (sintering at about 1600 to 2100 °C). Copper content per grade in the infiltration step was not read from a primary process source.
  - Radiation effects, thermal cycling and the Plansee WCu10 and WCu15 rows are not recorded beyond the typical values listed in the properties table.
sources:
  plansee-properties:
    title: 'Plansee Tungsten composites: properties, typical properties of WCu materials at 20 °C'
    url: https://www.plansee.com/en/materials/tungsten-composites/properties.html
    year: 2026
    kind: datasheet
    license: manufacturer web page, linked not reproduced
  plansee-materials:
    title: 'Plansee Tungsten composites: materials, WCu grades and nominal densities'
    url: https://www.plansee.com/en/materials/tungsten-composites/materials.html
    year: 2026
    kind: datasheet
    license: manufacturer web page, linked not reproduced
  plansee-wcu-sds:
    title: Plansee PDS-041, Product data sheet pursuant to REACH, WCu-composite material (valid from 12 July 2022)
    id: PSE-030-PDS-041, Version 00, Elmet and Plansee sites
    url: https://www.plansee.com/download/?DOKNR=PSE-030-PDS-041&DOKAR=QM1&DOKTL=100
    year: 2022
    kind: datasheet
    license: manufacturer safety data sheet, linked not reproduced
  tungsten-com:
    title: Tungsten.com, Tungsten Copper Alloy (W-Cu) material information, composition table
    url: https://www.tungsten.com/material-info/tungsten-copper-alloy-w-cu
    kind: datasheet
    license: supplier web page, linked not reproduced
  torrey-cuw:
    title: Torrey Hills Technologies, Properties of Copper Tungsten
    url: https://www.torreyhillstech.com/cuwdata.html
    kind: datasheet
    license: supplier web page, linked not reproduced
  svs-wcu:
    title: SVS Schweisstechnik, Tungsten-Copper (WCu), Physical and Mechanical Properties table
    url: https://www.svs-schweisstechnik.de/en/knowledge-hub/refractory-alloys/tungsten-copper-wcu/
    kind: datasheet
    license: supplier web page, linked not reproduced
  samaterials-cuw75:
    title: SA Materials, Tungsten Copper Composite CuW75, catalog WM7700
    url: https://www.samaterials.com/item/wm7700-tungsten-copper-composite-w-cu-composite-cuw75.html
    kind: datasheet
    license: supplier web page, linked not reproduced
  wikipedia-cuw:
    title: Copper-tungsten (CuW, WCu), Wikipedia
    url: https://en.wikipedia.org/wiki/Copper%E2%80%93tungsten
    kind: web
    license: CC BY-SA 4.0, linked not reproduced
  usgs-mcs2026-tungsten:
    title: Mineral Commodity Summaries 2026, Tungsten
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tungsten.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  us-patent-5705283:
    title: US Patent 5,705,283, Tungsten-copper composite material with rhenium protective layer, and its preparation
    url: https://patents.google.com/patent/US5705283A/en
    kind: report
    license: public domain (US patent)
  refractorymetal-rocket:
    title: Refractory Metal, Tungsten Copper Alloy for Rocket Throat Lining
    url: https://www.refractorymetal.org/tungsten-copper-alloy-for-rocket-throat-lining.html
    kind: web
    license: supplier web page, linked not reproduced
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 17
  unreachable: 1
  caveats: 5
  note: 'Values were read by an AI assistant on 2026-10-26 from the pages named in each entry. Unreachable: the ScienceDirect hybrid-rocket paper (HTTP 403, not cited in the file). The three Plansee pages return Access Denied to scripted fetches, so verify-values cannot read them; their values were read with WebFetch in this run. Caveats: supplier values for one grade disagree (bending strength 736 and 980 MPa; thermal conductivity 180 and 235 W/(m·K)); the Plansee table gives typical values, the SVS table minimum, typical or tolerance values without saying which; the oxidation temperatures are printed as approximate; the spacecraft evidence is limited to rocket nozzle parts.'
story:
  risk_groups:
    - title: For people
      lead: Plansee classifies its W-Cu composite as not hazardous under EU rules, but the dust it makes is a workplace exposure.
      level: 1
      verdict: Not classified, dust controlled
      points:
        - label: Classification
          line: The Plansee REACH data sheet prints no classification under Regulation (EC) No 1272/2008, and calls the material a compact metal or alloy with no risk to human health or the environment.
        - label: Dust
          line: Grinding or machining makes dust, which is a fire hazard and an inhalation exposure. The SDS asks for suction cleaning at source and at least one FFP2 respirator.
    - title: If it fails
      lead: The failure routes in these sources are oxidation in hot air and melting of the copper phase. None of them is a measured flight result.
      points:
        - label: Hot air
          line: Tungsten oxidises strongly in air from about 400 °C, and WO3 sublimes from about 850 °C, according to the Plansee SDS.
        - label: Copper melt
          line: Copper melts at 1083 °C (SDS) or about 1080 °C (patent), far below the tungsten melting point of 3410 °C.
    - title: Handling and storage
      points:
        - label: Dust
          line: Avoid dust formation, use suction cleaning, and wear an FFP2 respirator when dust is unavoidable.
        - label: Storage
          line: The SDS calls for no special storage measures.
  why: Tungsten-copper combines the heat resistance of tungsten with the conductivity of copper. The Plansee WCu20 grade, 80 % tungsten, has a thermal conductivity of 235 W/(m·K) at 20 °C and a thermal expansion of 8.3 ppm/K. A tungsten.com table gives W80Cu20 a density of 15.15 g/cm3 and an electrical conductivity of 34 %IACS. Those two properties are why the material is used as a heat sink and as an electrical contact.
  uses:
    - where: Heat sinks and contacts
      line: Plansee lists heat sinks, arcing contacts and electrodes among the products made from its W-Cu composite (Plansee SDS, Section 1).
    - where: Chip carriers
      line: Wikipedia says CuW75 is used as chip carriers and substrates for power semiconductors, with a thermal expansion matched to silicon and gallium arsenide.
    - where: Rocket nozzles
      line: US patent 5705283 proposes W-Cu for part or all of a rocket combustion chamber and expansion nozzle, and a supplier article calls it the preferred material for modern throat linings.
  can_do:
    - label: Carry heat
      value: 235 W/(m·K)
      benchmark: thermal_conductivity
      line: The Plansee WCu20 grade conducts heat at 235 W/(m·K) at 20 °C. A second supplier prints 180 W/(m·K) for a W80 grade at 25 °C.
    - label: Match thermal expansion
      value: 8.3 ppm/K
      benchmark: cte
      line: The coefficient of thermal expansion is 8.3 ppm/K at 20 °C for WCu20, and 8.8 ppm/K over 20 to 300 °C in the SVS W80/20 grade.
    - label: Carry current
      value: 34 %IACS
      line: W80Cu20 has an electrical conductivity of 34 %IACS in the tungsten.com table, against 38 to 45 %IACS in the SVS table for the same grade.
    - label: Hardness
      value: 220 HB Kgf/mm2
      line: W80Cu20 has a hardness of 220 HB Kgf/mm2 in the tungsten.com table, the same as in the Torrey Hills table.
  compare: 'Heavier grades carry more tungsten: the density is 14.5 g/cm3 for W75Cu25 and 15.15 g/cm3 for W80Cu20 in the tungsten.com table, while the electrical conductivity falls from 38 to 34 %IACS. These values come from different suppliers and grades, so read the table rows as examples, not as a ranking against copper or aluminium.'
  compare_rows:
    - label: Density
      benchmark: density
    - label: Thermal conductivity
      benchmark: thermal_conductivity
    - label: Thermal expansion
      benchmark: cte
  handling:
    - Specify the grade, because copper content changes density, conductivity and thermal expansion.
    - Keep dust down with suction cleaning and an FFP2 respirator.
    - Do not expose the composite to hot air above about 400 °C without protection.
  good_for:
    - 'Heat sinks: 235 W/(m·K) at 20 °C and 8.3 ppm/K in the Plansee WCu20 grade.'
    - 'Electrical contacts: 34 %IACS for W80Cu20 in the tungsten.com table.'
    - 'Rocket nozzle parts: the composite is proposed for combustion chamber and nozzle walls in US patent 5705283.'
  watch_out:
    - 'Hot air: strong oxidation begins around 400 °C, and WO3 sublimes from about 850 °C.'
    - 'Suppliers disagree: bending strength for W80Cu20 is 736 MPa in one table and 980 MPa in another, and thermal conductivity for a W80 grade is 180 or 235 W/(m·K) depending on the supplier.'
    - 'Weight: density 15.15 g/cm3 for W80Cu20 in the tungsten.com table.'
    - No outgassing or orbital erosion test for W-Cu was found in a readable source.
  verdict: Tungsten-copper is the standard heat sink and contact composite where tungsten's heat resistance and copper's conductivity are both needed. The Plansee WCu20 grade conducts heat at 235 W/(m·K) at 20 °C and expands at 8.3 ppm/K. It is heavy, oxidises in hot air from about 400 °C, and this profile has no flight or orbital test data for the material.
  recipe:
    line: Tungsten-copper is a metal matrix composite made by pressing and sintering tungsten powder into a porous skeleton, then infiltrating molten copper into it (Wikipedia). The sintering temperature is typically about 1600 to 2100 °C (US patent 5705283). Grades are named by their composition, so W80Cu20 has 80 wt % tungsten and 20 wt % copper, and Plansee names it WCu20.
    parts:
      - name: Tungsten
        symbol: W
        share: 80 wt % in W80Cu20 (75 wt % in W75Cu25)
        role: Sintered skeleton, which provides elevated-temperature strength (US patent 5705283).
      - name: Copper
        symbol: Cu
        share: 20 wt % in W80Cu20 (25 wt % in W75Cu25)
        role: Infiltrated phase, which adds ductility, toughness and thermal and electrical conductivity (US patent 5705283).