Silicon carbide SiC

spore: profile
id: silicon-carbide
spore_version: 0.2
family: carbide-nitride-boride-ceramics
name: Silicon carbide
abbreviation: SiC
role: "structural ceramic and power semiconductor (4H polytype)"
category: ceramics
type: carbides
summary: >
  Silicon carbide is a covalent carbide used both as a hard structural ceramic and as a wide-bandgap semiconductor. As a sintered
  ceramic, NIST's structural ceramics database gives a density of 3.08 g/cm3, an elastic modulus of 395 GPa, a four-point flexural
  strength of 346 MPa and a Vickers hardness of 23.9 GPa at 22 degC. As a semiconductor, a Toshiba reference table gives a band gap of
  3.26 eV for 4H-SiC, a breakdown field of 2.8 x 10^6 V/cm and a thermal conductivity of 4.9 W/cm·K, against 1.12 eV, 3 x 10^5 V/cm
  and 1.5 W/cm·K for silicon. Sources differ on some values, so the ranges are kept.
best_for: "Hard, stiff ceramic parts and high-voltage semiconductor devices where a wide band gap and high breakdown field matter (Toshiba's 4H-SiC table versus silicon)"
weakest_at: "Brittleness as a ceramic: flexural strength of 346 MPa and fracture toughness near 2.8 MPa·m½ for sintered material, and a Weibull modulus of 11.0 (NIST)"
identity:
  formula: "SiC, a compound of silicon and carbon (4H polytype in the semiconductor table)"
  source: toshiba-sic
  where: "Table comparing Si and 4H-SiC; the material is named 4H-SiC in the table"
tags:
  environments: []
  stresses: [extreme-heat]
  applications: [structures, electronics-and-chips]
properties:
  - benchmark: density
    label: Density, sintered SiC
    value: 3.08
    unit: g/cm3
    scope: material
    conditions: {material: "sintered alpha-SiC, 95.9 percent relative density, porosity 4.1 percent", uncertainty: "plus or minus 0.03 g/cm3"}
    method: "Archimedes' method, averaged (NIST)"
    status: ground
    source: nist-scd-z00021
    where: "Density (mass) section of the NIST Structural Ceramics Database entry Z00021"
  - benchmark: elastic_modulus
    label: Elastic modulus, sintered SiC
    value: 395
    unit: GPa
    scope: material
    conditions: {material: "sintered alpha-SiC", uncertainty: "plus or minus 10 GPa"}
    method: "Ultrasonic method (NIST)"
    status: ground
    source: nist-scd-z00021
    where: "Elastic Modulus section of NIST entry Z00021"
  - benchmark: flexural_strength
    label: Flexural strength, sintered SiC
    value: 346
    unit: MPa
    scope: material
    conditions: {temperature: "22 degC", uncertainty: "plus or minus 34 MPa", sample: "sintered alpha-SiC"}
    method: "Four-point bend test (NIST)"
    status: ground
    source: nist-scd-z00021
    where: "Flexural Strength section of NIST entry Z00021"
  - benchmark: hardness
    label: Vickers hardness, sintered SiC
    value: 23.9
    unit: GPa
    scope: material
    conditions: {temperature: "22 degC", uncertainty: "plus or minus 0.4 GPa"}
    method: "Vickers indentation (NIST)"
    status: ground
    source: nist-scd-z00021
    where: "Hardness section of NIST entry Z00021"
  - benchmark: fracture_toughness
    label: Fracture toughness, sintered SiC
    value: 2.78
    value_high: 2.82
    bound: range
    unit: MPa·m1/2
    scope: material
    conditions: {temperature: "22 degC", loads: "19.5, 29.4 and 34.3 N"}
    method: "Vickers indentation; three loads gave 2.82, 2.81 and 2.78 (NIST)"
    status: ground
    source: nist-scd-z00021
    where: "Fracture Toughness section of NIST entry Z00021"
  - benchmark: weibull_modulus
    label: Weibull modulus, sintered SiC
    value: 11.0
    unit: unitless
    scope: material
    conditions: {temperature: "22 degC"}
    method: "Four-point bend test (NIST)"
    status: ground
    source: nist-scd-z00021
    where: "Weibull Modulus section of NIST entry Z00021"
  - benchmark: density
    label: Density, polycrystalline SiC (NIST entry Z00009)
    value: 3.165
    unit: g/cm3
    scope: material
    conditions: {material: "polycrystalline SiC"}
    method: "Density (mass) section (NIST). NIST marks this value as unevaluated."
    status: ground
    source: nist-scd-z00009
    where: "Density (mass) section of NIST entry Z00009"
  - benchmark: elastic_modulus
    label: Elastic modulus, polycrystalline SiC (NIST entry Z00009)
    value: 421
    unit: GPa
    scope: material
    conditions: {temperature: "23 degC", uncertainty: "plus or minus 10 GPa"}
    method: "Elastic Modulus section (NIST), evaluated by acceptance criteria"
    status: ground
    source: nist-scd-z00009
    where: "Elastic Modulus section of NIST entry Z00009"
  - benchmark: tensile_strength
    label: Tensile strength, polycrystalline SiC (NIST entry Z00009)
    value: 160
    unit: MPa
    scope: material
    conditions: {temperature: "23 degC"}
    method: "Tensile Strength section (NIST), evaluated by acceptance criteria"
    status: ground
    source: nist-scd-z00009
    where: "Tensile Strength section of NIST entry Z00009"
  - benchmark: band_gap
    label: Band gap, 4H-SiC
    value: 3.26
    unit: eV
    scope: material
    conditions: {polytype: "4H-SiC", comparison: "silicon 1.12 eV in the same table"}
    method: "Vendor comparison table (Toshiba)"
    status: ground
    source: toshiba-sic
    where: "Table comparing Si and 4H-SiC, Band gap row"
  - benchmark: breakdown_field
    label: Electric breakdown field, 4H-SiC
    value: 2800000
    unit: V/cm
    scope: material
    conditions: {polytype: "4H-SiC", comparison: "silicon 3.0 x 10^5 V/cm in the same table"}
    method: "Vendor comparison table (Toshiba)"
    status: ground
    source: toshiba-sic
    where: "Table comparing Si and 4H-SiC, Electric breakdown field row"
  - benchmark: breakdown_field
    label: Breakdown field, 4H-SiC (general overview)
    value: 2.2
    unit: MV/cm
    scope: material
    conditions: {polytype: "not stated"}
    method: "General overview; quoted as roughly 2.2 MV/cm before breakdown"
    status: ground
    note: "Differs from the vendor table value of 2.8 x 10^6 V/cm; the sources do not say why."
    source: ieee-sic
    where: "Overview text on breakdown field"
  - benchmark: electron_mobility
    label: Electron mobility, 4H-SiC
    value: 1000
    value_high: 1200
    bound: range
    unit: cm2/Vs
    scope: material
    conditions: {polytype: "4H-SiC", comparison: "silicon 1400 cm2/Vs in the same table"}
    method: "Vendor comparison table (Toshiba), printed as 1000/1200"
    status: ground
    source: toshiba-sic
    where: "Table comparing Si and 4H-SiC, Electron mobility row"
  - benchmark: electron_mobility
    label: Electron mobility, bulk 4H-SiC (general overview)
    value: 900
    unit: cm2/Vs
    scope: material
    conditions: {polytype: "4H polytype, bulk"}
    method: "General overview text"
    status: ground
    source: ieee-sic
    where: "Overview text on electron mobility"
  - benchmark: saturated_drift_velocity
    label: Saturated electron drift velocity, 4H-SiC
    value: 2.2e7
    unit: cm/s
    scope: material
    conditions: {polytype: "4H-SiC", comparison: "silicon 1.0 x 10^7 cm/s in the same table"}
    method: "Vendor comparison table (Toshiba)"
    status: ground
    source: toshiba-sic
    where: "Table comparing Si and 4H-SiC, Saturated electron drift velocity row"
  - benchmark: thermal_conductivity
    label: Thermal conductivity, 4H-SiC
    value: 4.9
    unit: W/cmK
    scope: material
    conditions: {polytype: "4H-SiC", comparison: "silicon 1.5 W/cmK in the same table"}
    method: "Vendor comparison table (Toshiba), printed as W/cmK"
    status: ground
    source: toshiba-sic
    where: "Table comparing Si and 4H-SiC, Thermal conductivity row"
  - benchmark: thermal_conductivity
    label: Thermal conductivity, SiC (general overview)
    value: 3.7
    unit: W/cmK
    scope: material
    conditions: {basis: "stated to exceed copper"}
    method: "General overview text"
    status: ground
    note: "Differs from the vendor table value of 4.9 W/cmK; the sources do not explain the gap."
    source: ieee-sic
    where: "Overview text on thermal conductivity"
  - benchmark: dielectric_constant
    label: Relative dielectric constant, 4H-SiC
    value: 9.7
    value_high: 10.2
    bound: range
    unit: unitless
    scope: material
    conditions: {polytype: "4H-SiC", comparison: "silicon 11.8 in the same table"}
    method: "Vendor comparison table (Toshiba), printed as 9.7/10.2 without a unit"
    status: ground
    source: toshiba-sic
    where: "Table comparing Si and 4H-SiC, Relative dielectric constant row"
  - benchmark: density
    label: Density, reaction-bonded SiC
    value: 3.0
    unit: g/cm3
    scope: material
    conditions: {material: "reaction-bonded SiC, generic entry"}
    method: "Generic material property page; the page names no source for its values"
    status: ground
    note: "Unattributed reference page; treat as indicative only."
    source: makeitfrom-rbsc
    where: "Material properties table on the reaction-bonded SiC page"
  - benchmark: flexural_strength
    label: Flexural strength, reaction-bonded SiC
    value: 410
    unit: MPa
    scope: material
    conditions: {material: "reaction-bonded SiC, generic entry"}
    method: "Generic material property page; no source named"
    status: ground
    note: "Unattributed reference page; the NIST sintered value above is 346 MPa."
    source: makeitfrom-rbsc
    where: "Material properties table on the reaction-bonded SiC page"
  - benchmark: fracture_toughness
    label: Fracture toughness, reaction-bonded SiC
    value: 4.0
    unit: MPa·m1/2
    scope: material
    conditions: {material: "reaction-bonded SiC, generic entry"}
    method: "Generic material property page; no source named"
    status: ground
    note: "Unattributed reference page."
    source: makeitfrom-rbsc
    where: "Material properties table on the reaction-bonded SiC page"
  - benchmark: elastic_modulus
    label: Elastic modulus, reaction-bonded SiC
    value: 370
    unit: GPa
    scope: material
    conditions: {material: "reaction-bonded SiC, generic entry"}
    method: "Generic material property page; no source named"
    status: ground
    note: "Unattributed reference page; the NIST sintered value above is 395 GPa."
    source: makeitfrom-rbsc
    where: "Material properties table on the reaction-bonded SiC page"
  - benchmark: thermal_conductivity
    label: Thermal conductivity, reaction-bonded SiC
    value: 140
    unit: W/m·K
    scope: material
    conditions: {material: "reaction-bonded SiC, generic entry"}
    method: "Generic material property page; no source named"
    status: ground
    note: "Unattributed reference page."
    source: makeitfrom-rbsc
    where: "Material properties table on the reaction-bonded SiC page"
  - benchmark: max_service_temperature
    label: Maximum temperature, mechanical, reaction-bonded SiC
    value: 1160
    unit: degC
    scope: material
    conditions: {material: "reaction-bonded SiC, generic entry"}
    method: "Generic material property page; no source named"
    status: ground
    note: "Unattributed reference page."
    source: makeitfrom-rbsc
    where: "Material properties table on the reaction-bonded SiC page"
  - benchmark: flexural_strength
    label: Flexural strength, UltraSiC direct sintered SiC (CoorsTek)
    value: 480
    unit: MPa
    scope: material
    conditions: {temperature: "20 °C", grade: "UltraSiC, direct sintered"}
    method: "Flexural strength (MOR) row of CoorsTek datasheet"
    status: ground
    source: coors-sic-datasheet
    where: "Silicon Carbides datasheet, Flexural Strength (MOR) row, UltraSiC column"
  - benchmark: elastic_modulus
    label: Elastic modulus, UltraSiC direct sintered SiC (CoorsTek)
    value: 410
    unit: GPa
    scope: material
    conditions: {temperature: "20 °C", grade: "UltraSiC, direct sintered"}
    method: "Elastic Modulus row of CoorsTek datasheet"
    status: ground
    source: coors-sic-datasheet
    where: "Silicon Carbides datasheet, Elastic Modulus row, UltraSiC column"
  - benchmark: hardness
    label: Knoop hardness, UltraSiC direct sintered SiC (CoorsTek)
    value: 26
    unit: GPa
    scope: material
    conditions: {load: "Knoop 100 g", grade: "UltraSiC, direct sintered"}
    method: "Hardness, Knoop 100 g row. Knoop, not Vickers, so not comparable with the NIST 23.9 GPa value."
    status: ground
    source: coors-sic-datasheet
    where: "Silicon Carbides datasheet, Hardness Knoop 100 g row, UltraSiC column"
  - benchmark: fracture_toughness
    label: Fracture toughness (notched beam), UltraSiC (CoorsTek)
    value: 3.5
    unit: MPa·m1/2
    scope: material
    conditions: {method_detail: "notched beam, Klc", grade: "UltraSiC, direct sintered"}
    method: "Fracture Toughness Klc, notched beam row of CoorsTek datasheet"
    status: ground
    source: coors-sic-datasheet
    where: "Silicon Carbides datasheet, Fracture Toughness Klc row, UltraSiC column"
  - benchmark: thermal_conductivity
    label: Thermal conductivity, UltraSiC direct sintered SiC (CoorsTek)
    value: 150
    unit: W/m K
    scope: material
    conditions: {temperature: "20 °C", grade: "UltraSiC, direct sintered"}
    method: "Thermal Conductivity row of CoorsTek datasheet, printed in W/m K"
    status: ground
    source: coors-sic-datasheet
    where: "Silicon Carbides datasheet, Thermal Conductivity row, UltraSiC column"
  - benchmark: density
    label: Density, reaction-bonded SiC (CoorsTek SC-RB)
    value: 3.10
    unit: g/cm3
    scope: material
    conditions: {material: "reaction bonded, retains about 10 percent metallic silicon (datasheet text)"}
    method: "Density row of CoorsTek datasheet"
    status: ground
    source: coors-sic-datasheet
    where: "Silicon Carbides datasheet, Density row, SC-RB column"
  - benchmark: cte
    label: Coefficient of thermal expansion, UltraSiC (CoorsTek)
    value: 4.4
    unit: 10-6/°C
    scope: material
    conditions: {temperature_range: "25 to 1000 °C", grade: "UltraSiC, direct sintered"}
    method: "CTE row of CoorsTek datasheet, printed as 1 X 10-6/ °C"
    status: ground
    source: coors-sic-datasheet
    where: "Silicon Carbides datasheet, CTE row, UltraSiC column"
  - benchmark: specific_heat
    label: Specific heat, UltraSiC (CoorsTek)
    value: 800
    unit: J/kg-K
    scope: material
    conditions: {temperature: "100 °C", grade: "UltraSiC, direct sintered"}
    method: "Specific Heat row of CoorsTek datasheet"
    status: ground
    source: coors-sic-datasheet
    where: "Silicon Carbides datasheet, Specific Heat row, UltraSiC column"
corrosion:
  - environment: "Dry oxygen at high temperature (passive oxidation)"
    headline: "A protective SiO2 layer forms, but the scale is porous from 500 to 800 °C and seals the surface from 1200 to 1400 °C."
    effect: "Passive oxidation is SiC (s) + 3/2 O2 (g) to SiO2 (s) + CO (g). Biscay et al. say the silica layer can act as a protective barrier. Between 500 and 800 °C the scale is porous and loses mechanical properties. Between 1200 and 1400 °C the silica forms rapidly and seals the surface porosity."
    rating: unknown
    conditions: {temperature: "500 to 1400 °C, as the article gives it", atmosphere: "oxygen, high partial pressure favours passive oxidation"}
    source: biscay-2021
    where: "Section on dry oxidation of SiC (PMC full text)"
  - environment: "Low oxygen pressure at high temperature, or a cracked protective layer (active oxidation)"
    headline: "Active oxidation gives volatile SiO and CO; oxygen reaches the bulk through cracks or after the protective layer fails."
    effect: "The article gives active oxidation as SiC (s) + O2 to SiO (g) + CO (g), and says it occurs at the opposite conditions from passive oxidation. Oxygen reaches the bulk through cracks or after the protective layer fails. The article gives no numeric boundary between the two regimes."
    rating: unknown
    conditions: {atmosphere: "low oxygen partial pressure, elevated temperature"}
    source: biscay-2021
    where: "Section on dry oxidation of SiC (PMC full text)"
  - environment: "Hydrothermal and supercritical water"
    headline: "Hydrothermal conditions attack SiC by wet oxidation, supercritical water oxidation and hydrolysis."
    effect: "Biscay et al. say hydrothermal conditions cause chemical corrosion through three possible reactions (wet oxidation, supercritical water oxidation, hydrolysis) and that tribochemical corrosion also occurs under these conditions. No rates are given in the text read."
    rating: unknown
    conditions: {medium: "hydrothermal and supercritical water"}
    source: biscay-2021
    where: "Hydrothermal conditions section (PMC full text)"
risks:
  hazards:
    - text: "PubChem aggregated GHS for silicon carbide (CID 9863, signal word Danger): H350i, May cause cancer by inhalation. 70.3 percent of 1,053 company reports say the substance does not meet GHS hazard criteria. In a notification with H350i, H372 (16.1 percent of reports) adds: causes damage to organs through prolonged or repeated exposure."
      ghs:
        - H350i
        - H372
      source: pubchem-sic
      where: "Safety and Hazards, GHS Classification"
  failure_risks:
    - mode: "Brittle fracture of sintered ceramic"
      trigger: "Mechanical load on a flaw; Weibull modulus of 11.0 in the NIST test set"
      consequence: "Flexural strength of 346 MPa and fracture toughness of 2.78 to 2.82 MPa·m1/2 at 22 degC for sintered SiC"
      severity: moderate
      source: nist-scd-z00021
      where: "Flexural Strength, Fracture Toughness and Weibull Modulus sections of NIST entry Z00021"
    - mode: "Strength loss from oxidation in air at 500 to 800 °C"
      trigger: "Porous silica scale in dry oxygen, or cracks that let oxygen reach the bulk"
      consequence: "Biscay et al. say the porous scale loses mechanical properties in that range, and active oxidation starts once the protective layer cracks or fails"
      severity: moderate
      source: biscay-2021
      where: "Dry oxidation section (PMC full text)"
  side_effects: []
  handling:
    - text: "Dust: PubChem gives H350i (inhalation cancer) for silicon carbide. Control dust when machining or grinding. No supplier safety data sheet was read in this run."
      source: pubchem-sic
      where: "Safety and Hazards, GHS Classification"
  mitigations: []
uses:
  - application: optics-and-cameras
    device: "Lightweight CVD silicon carbide mirrors for LIDAR and space telescopes"
    example: "MI-CVD made three research mirrors for NASA Langley under a LIDAR contract, delivered in 1990. The article says the CVD process gives high purity and polishability, and that mirrors can be made from a few centimetres to 1.5 metres across."
    source: ntrs-20020083265
    where: "Mirror Technology article, pages on CVD silicon carbide and LIDAR mirrors"
  - application: structures
    device: "Sintered and reaction-bonded SiC wear and high-temperature parts"
    example: "CoorsTek lists direct sintered SiC in sizes up to 36 by 75 inches, reaction-bonded SiC for wear parts, and PureSiC CVD SiC up to 20 inches."
    source: coors-sic-datasheet
    where: "Silicon Carbides datasheet, product section text"
  - application: electronics-and-chips
    device: "SiC Schottky barrier diodes (power semiconductor)"
    example: "Toshiba's technical FAQ on SiC Schottky barrier diodes compares 4H-SiC with silicon for band gap, breakdown field, mobility and thermal conductivity, the properties that make it useful for power devices."
    source: toshiba-sic
    where: "Vendor FAQ page on SiC Schottky barrier diodes, comparison table"
supply:
  - subject: Silicon carbide (manufactured abrasive)
    abundance: "USGS: domestic resources are more than adequate for silicon carbide production. US net import reliance was 74 percent in 2025e. China supplied 88 percent of total US silicon carbide imports in 2021 to 2024."
    producers:
      - {country: China, share_percent: 45.0, year: 2025}
      - {country: Norway, share_percent: 8.0, year: 2025}
      - {country: Japan, share_percent: 6.0, year: 2025}
      - {country: Brazil, share_percent: 4.0, year: 2025}
    critical_lists: []
    recycling: "USGS: about 5 percent of silicon carbide is recycled."
    substitutes: ["USGS: natural and manufactured abrasives such as emery, garnet, metallic abrasives or staurolite can be substituted for silicon carbide in various applications."]
    source: usgs-mcs2026-abrasives
    where: "World Production Capacity table, 2025 (shares calculated by Space Mushroom: country capacity over the 1,000,000 t world total); Domestic Production and Use; Import Sources; Recycling; Substitutes"
  - subject: Silicon (feedstock for SiC's silicon half, and for ferrosilicon and polysilicon)
    abundance: "USGS: silicon materials are produced at about 80 percent China in 2025 (estimated)."
    producers:
      - {country: China, share_percent: 80, year: 2025}
    critical_lists:
      - {list: "USGS 2025 List of Critical Minerals (silicon added in the 2025 list)", listed: true}
    recycling: "Not stated in the USGS silicon chapter read."
    substitutes: []
    source: usgs-mcs2026-silicon
    where: "Events, Trends, and Issues (China almost 80 percent of global estimated silicon materials, 2025); Critical Minerals paragraph. The 80 percent is the USGS figure as printed, not a calculated share."
media: []
documents:
  - {title: "CoorsTek Silicon Carbides datasheet (PureSiC, SC-RB, UltraSiC grades)", type: datasheet, url: "https://www.coorstek.com/media/4249/silicon-carbides.pdf"}
  - {title: "NASA Mirror Technology article on MI-CVD silicon carbide mirrors", type: report, url: "https://ntrs.nasa.gov/api/citations/20020083265/downloads/20020083265.pdf"}
  - {title: "USGS Mineral Commodity Summaries 2026, silicon", type: report, url: "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silicon.pdf"}
  - {title: "USGS Mineral Commodity Summaries 2026, abrasives (manufactured)", type: report, url: "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-abrasives.pdf"}
  - {title: "PubChem compound record CID 9863, silicon carbide", type: database, url: "https://pubchem.ncbi.nlm.nih.gov/compound/9863"}
  - {title: "Biscay et al. 2021, Behavior of Silicon Carbide Materials under Dry to Hydrothermal Conditions, Nanomaterials 11(5):1351", type: paper, url: "https://pmc.ncbi.nlm.nih.gov/articles/PMC8161094"}
  - {title: "Toshiba semiconductor knowledge base: SiC SBD FAQ, Si and 4H-SiC property table", type: datasheet, url: "https://toshiba.semicon-storage.com/ap-en/semiconductor/knowledge/faq/diode_sic-sbd/sic-sbd001.html"}
  - {title: "NIST Structural Ceramics Database, entry Z00021 (sintered SiC)", type: database, url: "https://srdata.nist.gov/CeramicDataPortal/Scd/Z00021"}
  - {title: "NIST Structural Ceramics Database, entry Z00009 (polycrystalline SiC)", type: database, url: "https://srdata.nist.gov/CeramicDataPortal/Scd/Z00009"}
gaps:
  - "Wolfspeed: the datasheet page returned no content (34 bytes), so no Wolfspeed value is used."
  - "Saint-Gobain and Morgan silicon carbide datasheets were not read in this run."
  - "Molten salt corrosion of SiC: no source read."
  - "Acheson process and the 3C and 6H polytypes: not read. The recipe names only 4H and the CVD and sintering routes."
  - "Composition by weight (Si and C shares) is not computed: no atomic weight table was read in this run."
  - "Herschel and Gaia SiC mirror use: a search returned no document naming them, and no ESA source was read."
  - "Brake disc and armour uses: not sourced in this run."
  - "Crystalline silica dust hazard: no source read. PubChem gives H350i only and no supplier SDS was read."
  - "Oxidation rates and oxide thickness: the Biscay 2021 review gives mechanism and qualitative temperature ranges only, with no numbers for rates."
  - "The NIST, Toshiba and CoorsTek values use different methods (Knoop vs Vickers, notched beam vs indentation); they are kept separate and not compared as one scale."
sources:
  coors-sic-datasheet:
    title: "CoorsTek, Silicon Carbides datasheet (PureSiC CVD, SC-RB, UltraSiC grades)"
    url: "https://www.coorstek.com/media/4249/silicon-carbides.pdf"
    kind: datasheet
    license: "vendor datasheet, cited not reproduced"
  ntrs-20020083265:
    title: "NASA Industrial Productivity and Manufacturing Technology, Mirror Technology (MI-CVD silicon carbide mirrors)"
    url: "https://ntrs.nasa.gov/api/citations/20020083265/downloads/20020083265.pdf"
    kind: report
    license: "NASA public document"
  usgs-mcs2026-silicon:
    title: "USGS Mineral Commodity Summaries 2026, Silicon"
    url: "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silicon.pdf"
    kind: report
    license: "US government work, public domain"
  usgs-mcs2026-abrasives:
    title: "USGS Mineral Commodity Summaries 2026, Abrasives (Manufactured)"
    url: "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-abrasives.pdf"
    kind: report
    license: "US government work, public domain"
  pubchem-sic:
    title: "PubChem compound CID 9863, Silicon carbide (GHS classification, aggregated notifications)"
    url: "https://pubchem.ncbi.nlm.nih.gov/compound/9863"
    kind: database
    license: "PubChem public database"
  biscay-2021:
    title: "Biscay et al., Behavior of Silicon Carbide Materials under Dry to Hydrothermal Conditions, Nanomaterials 2021, 11(5):1351"
    url: "https://pmc.ncbi.nlm.nih.gov/articles/PMC8161094"
    kind: paper
    license: "open access review (CC-BY per PMC)"
  toshiba-sic:
    title: "Toshiba semiconductor knowledge base: SiC Schottky barrier diodes FAQ, table comparing Si and 4H-SiC"
    url: "https://toshiba.semicon-storage.com/ap-en/semiconductor/knowledge/faq/diode_sic-sbd/sic-sbd001.html"
    kind: web
    license: "vendor web page, cited not reproduced"
  nist-scd-z00021:
    title: "NIST Structural Ceramics Database, entry Z00021 (sintered SiC)"
    url: "https://srdata.nist.gov/CeramicDataPortal/Scd/Z00021"
    kind: database
    license: "public domain (NIST)"
  nist-scd-z00009:
    title: "NIST Structural Ceramics Database, entry Z00009 (polycrystalline SiC)"
    url: "https://srdata.nist.gov/CeramicDataPortal/Scd/Z00009"
    kind: database
    license: "public domain (NIST)"
  ieee-sic:
    title: "IEEE Technology Navigator, silicon carbide topic page"
    url: "https://technav.ieee.org/topic/silicon-carbide/"
    kind: web
    license: "IEEE web page, cited not reproduced"
  makeitfrom-rbsc:
    title: "MakeItFrom.com, Reaction Bonded Silicon Carbide material properties (no source named)"
    url: "https://www.makeitfrom.com/material-properties/Reaction-Bonded-Silicon-Carbide"
    kind: web
    license: "web page, cited not reproduced"
license: CC-BY-4.0

updated: "2026-10-19"
review:
  status: draft
  method: assistant
  checked_values: 32
  unreachable: 4
  caveats: 4
  note: "Deepened in this run: CoorsTek datasheet, USGS silicon and abrasives, PubChem GHS, NASA mirror article and Biscay 2021 review were read. Wolfspeed and Saint-Gobain were not readable; molten salt and Acheson process remain unsourced."

story:
  recipe:
    line: "Silicon carbide is a compound of one silicon atom and one carbon atom in a tetrahedral crystal. The 4H polytype is a stacking arrangement of those layers that is used in power semiconductors. CoorsTek makes bulk SiC three ways, by CVD (PureSiC), by direct sintering (UltraSiC) or by reaction bonding, which keeps about 10 percent metallic silicon (CoorsTek datasheet). MI-CVD grew bulk SiC by chemical vapor deposition for NASA mirrors (NASA article)."
    parts:
      - {name: Silicon, symbol: Si, atoms: 1, role: "Forms tetrahedral bonds with carbon. The hard, stiff network it makes is the source of the material's strength and hardness."}
      - {name: Carbon, symbol: C, atoms: 1, role: "The second half of the covalent network. Carbon in SiC gives the wide band gap that separates it from silicon."}
  risk_groups:
    - title: "For people"
      level: 0
      verdict: "PubChem lists a cancer hazard by inhalation (H350i)"
      lead: "PubChem's aggregated GHS entry for silicon carbide carries the H350i statement, with a Danger signal word. Most company reports say it does not meet GHS criteria, so treat this as a precaution."
      points:
        - label: "Dust"
          line: "Machining or grinding SiC ceramic can make fine dust. Check the supplier's safety data sheet before handling powder or machining parts."
        - label: "Inhalation"
          line: "H350i (may cause cancer by inhalation) and H372 (organ damage from prolonged exposure) appear in PubChem's notifications. 70.3 percent of 1,053 reports say it does not meet GHS criteria."
    - title: "If a part fails"
      lead: "These numbers are from the mechanical test entries in NIST's database."
      points:
        - label: "Brittleness"
          line: "Sintered SiC has a flexural strength of 346 MPa and a fracture toughness of 2.78 to 2.82 MPa·m1/2 at 22 degC, so it breaks rather than bends. Its Weibull modulus is 11.0, which means strength varies from part to part."
  why: >-
    Silicon carbide is used for two different reasons. As a ceramic it is hard and stiff, with an elastic modulus of 395 GPa and
    a Vickers hardness of 23.9 GPa for sintered material. As a semiconductor, its 4H polytype has a band gap of 3.26 eV, which
    is about three times that of silicon, and a breakdown field of 2.8 x 10^6 V/cm, which is about nine times that of silicon.
    Those two facts are why it appears in power devices.
  uses:
    - where: "Mirrors for LIDAR and space optics"
      line: >-
        MI-CVD made three research SiC mirrors for NASA Langley, delivered in 1990. The article says CVD SiC polishes well and can be made from a few centimetres up to 1.5 metres.
    - where: "Power semiconductors"
      line: >-
        Toshiba's FAQ on SiC Schottky barrier diodes compares 4H-SiC with silicon on band gap, breakdown field, mobility and
        thermal conductivity. Those figures are the reason the material is considered for power devices.
  can_do:
    - label: "Stiffness"
      benchmark: elastic_modulus
      line: >-
        Sintered SiC has an elastic modulus of 395 GPa, plus or minus 10 GPa, from NIST's ultrasonic measurement.
    - label: "Hardness"
      benchmark: hardness
      line: >-
        The Vickers hardness of sintered SiC is 23.9 GPa at 22 degC, measured by indentation.
    - label: "Band gap"
      benchmark: band_gap
      value: 3.26 eV
      line: >-
        The 4H polytype has a band gap of 3.26 eV, against 1.12 eV for silicon in the same Toshiba table.
    - label: "Thermal conduction"
      benchmark: thermal_conductivity
      value: 4.9 W/cmK
      line: >-
        Toshiba gives 4.9 W/cmK for 4H-SiC. The general overview gives 3.7 W/cmK. The sources do not agree.
  compare: >-
    Compared with silicon, 4H-SiC has a band gap of 3.26 eV against 1.12 eV, a breakdown field of 2.8 x 10^6 V/cm against 3.0 x
    10^5 V/cm, and a thermal conductivity of 4.9 W/cmK against 1.5 W/cmK, all from one Toshiba table. Its electron mobility is
    lower, at 1000 to 1200 cm2/Vs against 1400 cm2/Vs for silicon. The table compares SiC with silicon, not with other ceramics.
  compare_rows:
    - {label: "Band gap", benchmark: band_gap}
    - {label: "Breakdown field", benchmark: breakdown_field}
    - {label: "Thermal conductivity", benchmark: thermal_conductivity}
  handling:
    - "Sintered SiC is brittle. Design for tension and bending loads with a safety margin."
    - "Machining SiC ceramic makes dust. PubChem lists H350i (cancer by inhalation), so control dust and check the supplier's safety data sheet."
    - "Oxidation: in dry oxygen at 500 to 800 C the silica scale is porous and loses strength (Biscay 2021)."
  good_for:
    - "Hard, stiff parts. NIST's sintered SiC has a Vickers hardness of 23.9 GPa and an elastic modulus of 395 GPa."
    - "High-voltage power devices. The 4H polytype's band gap of 3.26 eV and breakdown field of 2.8 x 10^6 V/cm are well above silicon's in the Toshiba table."
  watch_out:
    - "Brittleness. The flexural strength of sintered SiC is 346 MPa and its Weibull modulus is 11.0."
    - "The sources disagree. The breakdown field is 2.8 x 10^6 V/cm in the Toshiba table and about 2.2 MV/cm in the IEEE overview."
    - "Brake disc, armour, Herschel and Gaia uses, and molten-salt corrosion, were not sourced in this run."
  verdict: "Silicon carbide is a stiff, hard ceramic and a wide-band-gap semiconductor. Sourced numbers now cover both roles, the supply chain (USGS) and oxidation (Biscay 2021). Armour, brake disc and molten-salt uses remain unsourced."