Silver-tungsten W-Ag

spore: profile
id: silver-tungsten
spore_version: 0.2
family: refractory-metals
name: Silver-tungsten
abbreviation: W-Ag
role: electrical contact and electrode composite
category: metals
type: refractory-metals
summary: |
  Silver-tungsten (W-Ag, also written AgW) is a pseudo-alloy, not a true alloy. Goodfellow describes it as tungsten particles in a silver matrix, and it is made by powder metallurgy (Goodfellow; a 2006 powder metallurgy congress paper). One supplier data sheet for ASTM B631 rod lists grades from AgW30, with 70 % silver, to AgW80, with 20 % silver, with conductivity of 37 to 75 % and bending strength of 657 to 726 MPa. Goodfellow lists its W90/Ag10 composite for switchgear contacts, relays and circuit breakers. Silver tarnishes in air that contains sulfur compounds.
best_for: Electrical contacts for switchgear, relays and circuit breakers (uses listed by Goodfellow)
weakest_at: 'Tarnish in sulfur-containing air, and few sourced numbers: no thermal, flight or vacuum data for the composite was found in a readable source'
identity:
  formula: 'Tungsten-silver composite: tungsten (W) particles in a silver (Ag) matrix, 20 to 70 % Ag in the grades of one supplier (AgW80 to AgW30), tungsten the balance'
  source: sam-wag-tds
  where: Chemical Composition table, Ag % and W % columns, rows AgW30 to AgW80
  designations:
    - system: ASTM
      code: B631
      note: rod, ASTM B631 silver-tungsten composite
      source: sam-wag-tds
      where: Specification table, Standard row
    - system: Trade name
      code: AgW50
      note: one supplier grade with 50 % Ag, tungsten the balance
      source: sam-wag-tds
      where: Chemical Composition table, row AgW50
    - system: Trade name
      code: W90/Ag10
      note: composite named by one other supplier, 10 % Ag
      source: goodfellow-wag
      where: Page title and Material Overview
tags:
  applications:
    - electronics-and-chips
    - mechanisms
properties:
  - benchmark: density
    label: Density, AgW30 to AgW80 (data sheet range)
    value: 11.75
    value_high: 16.1
    bound: range
    unit: g/cm3
    scope: material
    conditions:
      grade: AgW30 to AgW80 (70 % to 20 % Ag)
      temperature: not printed on the page
    method: Range printed in a supplier technical data sheet for ASTM B631 rod; the page does not say which grade gives which value
    status: ground
    source: sam-wag-tds
    where: Properties table, row Density, unit g/cm3
  - benchmark: electrical_resistivity
    label: Electrical resistivity, AgW30 to AgW80 (data sheet range)
    value: 2.3
    value_high: 4.6
    bound: range
    unit: µΩ·cm
    scope: material
    conditions:
      grade: AgW30 to AgW80 (70 % to 20 % Ag)
      temperature: not printed on the page
    method: Range printed in a supplier technical data sheet
    status: ground
    source: sam-wag-tds
    where: Properties table, row Resistivity, unit µΩ·cm
  - benchmark: electrical_conductivity
    label: Electrical conductivity, AgW30 to AgW80 (data sheet range)
    value: 37
    value_high: 75
    bound: range
    unit: '%'
    scope: material
    conditions:
      grade: AgW30 to AgW80 (70 % to 20 % Ag)
      temperature: not printed on the page
    method: Range printed in a supplier technical data sheet; the page gives % only, not %IACS, so the basis is not known
    status: ground
    note: The IACS basis is not stated, so the range is not compared with copper or aluminium percentages.
    source: sam-wag-tds
    where: Properties table, row Conductivity, unit %
  - benchmark: flexural_strength
    label: Bending strength, AgW30 to AgW80 (data sheet range)
    value: 657
    value_high: 726
    bound: range
    unit: MPa
    scope: material
    conditions:
      grade: AgW30 to AgW80 (70 % to 20 % Ag)
      temperature: not printed on the page
    method: Range printed in a supplier technical data sheet
    status: ground
    source: sam-wag-tds
    where: Properties table, row Bending Strength, unit Mpa
  - benchmark: hardness
    label: Hardness, AgW30 to AgW80 (data sheet range)
    value: 75
    value_high: 180
    bound: range
    unit: '-'
    scope: material
    conditions:
      grade: AgW30 to AgW80 (70 % to 20 % Ag)
      temperature: not printed on the page
    method: Range printed in a supplier technical data sheet; the unit column shows a dash, so the hardness scale is not stated
    status: ground
    note: No scale is printed, so this value is not compared with Brinell or Vickers figures.
    source: sam-wag-tds
    where: Properties table, row Hardness, unit column shows -
  - benchmark: hardness
    label: Hardness, as-sintered W+30 wt % Ag (2006 study)
    value: 130
    unit: HB
    scope: material
    conditions:
      composition: W+30 wt % Ag
      process: double-pressed and double-sintered at 1100 °C for one hour in hydrogen (as-sintered)
      temperature: not printed on the page
    method: Value printed in Table 2 of a 2006 powder metallurgy congress paper, as-sintered rows
    status: ground
    source: koreascience-wag
    where: Table 2, As-sintered composites, row W+30%Ag, column Hardness [HB]
  - benchmark: flexural_strength
    label: Bending strength, as-sintered W+30 wt % Ag (2006 study)
    value: 260
    unit: MPa
    scope: material
    conditions:
      composition: W+30 wt % Ag
      process: double-pressed and double-sintered at 1100 °C for one hour in hydrogen (as-sintered)
      temperature: not printed on the page
    method: Value printed in Table 2 of a 2006 powder metallurgy congress paper, as-sintered rows
    status: ground
    source: koreascience-wag
    where: Table 2, As-sintered composites, row W+30%Ag, column Bending Strength [Mpa]
corrosion:
  - environment: Air containing sulfur compounds
    headline: Silver tarnishes in air to form black silver sulfide, the film that forms on silver exposed to sulfur.
    effect: The Wikipedia silver article says silver does not react with air even at red heat, but in the presence of sulfur compounds it tarnishes in air to form black silver sulfide. The article gives no rate, and no contact-resistance figure is recorded here.
    rating: moderate
    conditions:
      basis: qualitative statement, no rate or concentration given
      product: silver phase of the composite
    source: wikipedia-silver
    where: Article text, statements on air and tarnishing
  - environment: Air at red heat
    headline: Tungsten reacts with oxygen when red-hot to form the trioxide WO3.
    effect: The Wikipedia tungsten article says tungsten does not react with oxygen or air at room temperature, but at elevated temperatures (red-hot) it reacts with oxygen to form WO3. No oxidation rate is given.
    rating: moderate
    conditions:
      basis: qualitative statement, no temperature or rate given
      product: tungsten phase of the composite
    source: wikipedia-tungsten
    where: Article text, statements on reaction with oxygen
risks:
  hazards:
    - text: PubChem's aggregated GHS notifications for silver metal list very toxic to aquatic life (H400, 70.4 % of notifications) and very toxic with long-lasting effects (H410, 69.3 %). These are for silver metal, not for the composite.
      ghs:
        - H400
        - H410
      source: pubchem-silver
      where: Safety and Hazards, GHS Classification, aggregated statements
    - text: Finely divided tungsten is pyrophoric, so the powder form needs its own hazard review.
      ghs: []
      source: wikipedia-tungsten
      where: Article text, pyrophoric statement
  failure_risks:
    - mode: Tarnish of the silver phase
      trigger: Exposure to air that contains sulfur compounds
      consequence: A black silver sulfide film forms on the silver. The source gives no rate and no effect on contact resistance.
      severity: moderate
      source: wikipedia-silver
      where: Article text, tarnishing statement
    - mode: Oxidation of the tungsten phase in hot air
      trigger: Air at red heat
      consequence: Tungsten reacts with oxygen to form WO3. The source gives no oxidation rate.
      severity: moderate
      source: wikipedia-tungsten
      where: Article text, reaction with oxygen statement
  side_effects: []
  handling:
    - text: Treat finely divided tungsten powder as pyrophoric, and plan for fire when it is handled.
      source: wikipedia-tungsten
      where: Article text, pyrophoric statement
    - text: Silver tarnishes in sulfur-containing air, so keep contacts in clean, sulfur-free packaging until they are fitted. This is a precaution drawn from the tarnish statement, not a tested storage condition.
      source: wikipedia-silver
      where: Article text, tarnishing statement
    - text: Specify the grade, because silver content changes density, conductivity and strength across the data sheet range.
      source: sam-wag-tds
      where: Chemical Composition table; Properties table
  mitigations: []
uses:
  - application: electronics-and-chips
    device: Switchgear contacts, relays and circuit breakers
    example: Goodfellow lists its W90/Ag10 composite for switchgear contacts, relays and circuit breakers. It also presents the material as a lower-cost option to palladium-silver alloys in sulfur-bearing environments.
    source: goodfellow-wag
    where: Applications and Advantages section
  - application: mechanisms
    device: Aerospace actuators and connectors
    example: Goodfellow lists aerospace connectors and actuators among the applications of its W-Ag composite. No flight record was found in this run.
    source: goodfellow-wag
    where: Applications and Advantages section
supply:
  - subject: Tungsten (world mine production, the tungsten content of W-Ag)
    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 quantity of secondary tungsten produced in 2025 is withheld to avoid disclosing company proprietary data.'
    substitutes:
      - 'USGS: depleted uranium or lead for tungsten or tungsten alloys in applications requiring high density or the ability to shield radiation.'
    source: usgs-mcs2026-tungsten
    where: 'World Mine Production and Reserves table, 2025 column: China 67,000; Vietnam 3,000; Kazakhstan 2,400; Russia 2,000; world total 85,000 t, tungsten content. Shares calculated here (67,000 / 85,000 = 78.8 %). Recycling and Substitutes sections.'
  - subject: Silver (world mine production)
    producers:
      - country: Mexico
        share_percent: 24.2
        year: 2025
      - country: Peru
        share_percent: 13.8
        year: 2025
      - country: China
        share_percent: 13.1
        year: 2025
      - country: Bolivia
        share_percent: 5.8
        year: 2025
    critical_lists:
      - list: USGS 2025 Final List of Critical Minerals (silver added in 2025)
        listed: true
    recycling: 'USGS: about 1,000 tons of silver was recovered from new and old scrap in 2025, about 11 % of apparent consumption.'
    substitutes: []
    source: usgs-mcs2026-silver
    where: 'World Mine Production and Reserves table, mine production 2025e, silver content in metric tons: Mexico 6,300; Peru 3,600; China 3,400; Bolivia 1,500; world total 26,000. Shares calculated here. Critical minerals and Recycling text.'
documents:
  - title: Stanford Advanced Materials, Technical Data Sheet, Tungsten Silver Composite, catalog SV0138 (ASTM B631)
    type: datasheet
    url: https://samaterials.com/tds/1718617741-SV0138.pdf
  - title: Goodfellow, Tungsten/Silver W90/Ag10 material information
    type: datasheet
    url: https://www.goodfellow.com/usa/resources/tungsten-silver-w90-ag10-material-information/
  - title: Leżański and Madej, The Influence of Production Process Parameters on Properties of W-Ag, Mo-Ag Composites (2006 Powder Metallurgy World Congress, PC11-W-02)
    type: paper
    url: https://koreascience.kr/article/CFKO200617317791372.pdf
    year: 2006
  - title: 'USGS Mineral Commodity Summaries 2026: Silver'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silver.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Tungsten'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tungsten.pdf
    year: 2026
  - title: PubChem compound record, Silver (CID 23954), GHS classification
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/23954
    year: 2026
  - title: 'Wikipedia: Silver'
    type: database
    url: https://en.wikipedia.org/wiki/Silver
  - title: 'Wikipedia: Tungsten'
    type: database
    url: https://en.wikipedia.org/wiki/Tungsten
gaps:
  - Only seven values are recorded. No thermal conductivity, thermal expansion, melting point or %IACS value for the composite was found in a readable source in this run, so the profile is below the 12-property target.
  - The hardness scale is not printed on the supplier data sheet (unit column shows a dash). The range is recorded with unit - and no scale is inferred.
  - The supplier conductivity is printed as % with no IACS basis.
  - The 2006 paper's as-infiltrated rows (251 HB, 650 MPa) are labelled W+30%Ag, but its infiltration text describes W+5 wt % Ag compacts infiltrated with Ag-1 wt % Ni. Those rows are not recorded because the composition is unclear.
  - The 2006 paper's relative density values (87,5 % and 97,2 %) are printed with a decimal comma and are not recorded.
  - Goodfellow's page gives 19.3 g/cm3 and 3422 °C, which are tungsten values, and 63 × 10⁶ S/m, which is silver. None is recorded as a property of the composite.
  - EDM electrode use is not confirmed. Supplier EDM grade pages (Hogen Durakut H20S, Ampco) returned HTTP 403 or did not list silver-tungsten, so no EDM grade or EDM data is recorded.
  - No UNS, EN, DIN, JIS or W.Nr. number for silver-tungsten was found on a page read in this run.
  - 'Critical-mineral status for tungsten: the USGS 2026 tungsten text read here does not print a critical-minerals entry, so critical_lists is empty. The EU critical raw materials list was not checked for silver or tungsten.'
  - The USGS silver text names no substitute for silver in electrical contacts, so substitutes is empty.
  - No outgassing, mass loss, atomic-oxygen or cold-welding result for W-Ag in vacuum or low Earth orbit was found in a readable source. No spacecraft flight use was found.
  - Silver tarnish rates and contact-resistance effects are not quantified. The DTIC report on silver sulfide and the IEEE article were not readable in this run (DTIC returned an HTML page).
  - No W-Ag safety data sheet was read. Hazards come from the PubChem silver notifications and the Wikipedia tungsten pyrophoric statement.
  - Atomic weights were not recorded, so the recipe gives shares only.
  - No media were added, because no image was fetched and licence-checked in this run.
sources:
  sam-wag-tds:
    title: Stanford Advanced Materials, Technical Data Sheet, Tungsten Silver Composite, catalog SV0138, standard ASTM B631
    url: https://samaterials.com/tds/1718617741-SV0138.pdf
    kind: datasheet
    license: supplier data sheet, linked not reproduced
  goodfellow-wag:
    title: Goodfellow, Tungsten/Silver W90/Ag10 material information
    url: https://www.goodfellow.com/usa/resources/tungsten-silver-w90-ag10-material-information/
    kind: web
    license: supplier web page, linked not reproduced
  koreascience-wag:
    title: Leżański and Madej, The Influence of Production Process Parameters on Properties W-Ag, Mo-Ag Composites, 2006 Powder Metallurgy World Congress
    url: https://koreascience.kr/article/CFKO200617317791372.pdf
    kind: paper
    license: conference paper, linked not reproduced
  usgs-mcs2026-silver:
    title: Mineral Commodity Summaries 2026, Silver
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silver.pdf
    kind: report
    license: public domain (USGS)
  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
    kind: report
    license: public domain (USGS)
  pubchem-silver:
    title: PubChem compound record, Silver (CID 23954)
    id: CID 23954
    url: https://pubchem.ncbi.nlm.nih.gov/compound/23954
    kind: database
    license: public domain (NCBI)
  wikipedia-silver:
    title: Wikipedia, Silver
    url: https://en.wikipedia.org/wiki/Silver
    kind: web
    license: CC BY-SA 4.0, linked not reproduced
  wikipedia-tungsten:
    title: Wikipedia, Tungsten
    url: https://en.wikipedia.org/wiki/Tungsten
    kind: web
    license: CC BY-SA 4.0, linked not reproduced
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 7
  unreachable: 4
  caveats: 3
  note: 'Values were read by an AI assistant on 2026-10-26 from the pages named in each entry. Unreachable in this run: the Hogen and Prospector EDM grade page (HTTP 403), the GlobalSpec EDM page (HTTP 403), the tungsten.com silver-tungsten page (HTTP 404), and the DTIC silver sulfide report (HTML page, not a PDF). Caveats: the supplier data sheet gives ranges across grades and does not say which grade gives which value; its conductivity has no IACS basis; the hardness has no scale.'
story:
  recipe:
    line: Silver-tungsten is a composite of tungsten particles in a silver matrix, not a true alloy (Goodfellow). In a 2006 study, W+30 wt % Ag was made by mixing the powders, pressing at 600 MPa in a rigid die, and sintering twice at 1100 °C for one hour in hydrogen (Korean paper). The same paper also describes infiltration, in which a porous tungsten skeleton is sintered in hydrogen and then infiltrated with liquid silver alloy (Korean paper).
    parts:
      - name: Tungsten
        symbol: W
        share: 30 to 80 % (basis not stated on the data sheet)
        role: Refractory particle phase embedded in the silver matrix (Goodfellow).
      - name: Silver
        symbol: Ag
        share: 20 to 70 % (basis not stated on the data sheet)
        role: Matrix phase in which the tungsten particles sit (Goodfellow).
  risk_groups:
    - title: For people
      level: 1
      verdict: No composite classification found
      lead: The sources read here give no hazard classification for the composite. The hazards found are for silver metal and for powdered tungsten.
      points:
        - label: Powder
          line: Finely divided tungsten is pyrophoric (Wikipedia). Treat the powder form as a fire hazard.
        - label: Silver
          line: PubChem's aggregated GHS notifications for silver metal list H400 and H410, very toxic to aquatic life. These are not specific to the composite.
    - title: If it fails
      lead: 'The sources name two failure routes: tarnish on the silver phase, and oxidation of the tungsten phase in hot air. No flight or vacuum test was found.'
      points:
        - label: Tarnish
          line: Silver tarnishes in air that contains sulfur compounds, forming black silver sulfide. No rate or contact-resistance figure was found.
        - label: Hot air
          line: Tungsten reacts with oxygen when red-hot to form WO3. No oxidation rate was found.
    - title: Handling and storage
      points:
        - label: Grade
          line: Specify the silver content. The supplier grades run from 20 to 70 % silver.
        - label: Storage
          line: Keep contacts in clean, sulfur-free packaging. This is a precaution, not a tested storage condition.
  why: Silver-tungsten pairs a refractory tungsten phase with a silver phase that carries current. The supplier range for conductivity is 37 to 75 %, and the bending strength range is 657 to 726 MPa. Because the two metals are combined by powder metallurgy rather than melted into one alloy, the material is a composite whose properties depend on the silver content. Goodfellow lists it for switchgear contacts, relays and circuit breakers, which explains its use in electrical contacts.
  uses:
    - where: Switchgear, relays and circuit breakers
      line: Goodfellow lists its W90/Ag10 composite for switchgear contacts, relays and circuit breakers.
    - where: Aerospace connectors and actuators
      line: Goodfellow lists aerospace connectors and actuators among the applications. No flight record was found.
  can_do:
    - label: Conductivity
      value: 37 to 75 %
      benchmark: electrical_conductivity
      line: The supplier range for ASTM B631 rod grades from AgW80 to AgW30 is 37 to 75 %. The data sheet does not state the IACS basis.
    - label: Bending strength
      value: 657 to 726 MPa
      benchmark: flexural_strength
      line: The supplier range for the same grades is 657 to 726 MPa.
    - label: Hardness
      value: 75 to 180
      benchmark: hardness
      line: The data sheet hardness range is 75 to 180. No scale is printed, so the figure cannot be read against Brinell or Vickers values.
  compare: 'Within the supplier range, silver content sets the balance: the data sheet lists 20 to 70 % silver across the AgW grades, and the conductivity and bending strength ranges are each wide. The 2006 study adds one as-sintered point at W+30 wt % Ag (130 HB, 260 MPa). No number here is compared with copper-tungsten or other contact materials, because no comparable value was read in this run.'
  compare_rows:
    - label: Density
      benchmark: density
    - label: Electrical conductivity
      benchmark: electrical_conductivity
    - label: Bending strength
      benchmark: flexural_strength
  handling:
    - Specify the grade, because silver content changes density, conductivity and strength across the data sheet range.
    - Keep finely divided tungsten powder under a fire plan, since it is pyrophoric.
    - Keep silver contacts in clean, sulfur-free packaging to limit tarnish.
  good_for:
    - Electrical contacts for switchgear, relays and circuit breakers, per Goodfellow's listed uses.
    - 'Grade choice where conductivity matters: the data sheet gives 37 to 75 % across grades, so specify the grade.'
  watch_out:
    - Silver tarnish in sulfur-containing air (Wikipedia).
    - 'Hot air above red heat: tungsten reacts with oxygen to form WO3 (Wikipedia).'
    - 'Broad supplier ranges: density 11.75 to 16.1 g/cm3 and conductivity 37 to 75 % across the grades.'
    - No thermal conductivity, thermal expansion or vacuum data for this composite was found in a readable source.
  verdict: 'Silver-tungsten is a composite for electrical contacts. The supplier range is wide: conductivity from 37 to 75 % and bending strength from 657 to 726 MPa across the grades. Its limits are tarnish in sulfur-containing air and oxidation of the tungsten phase in hot air. This profile has seven sourced values and no flight or vacuum data.'