Structural graphite Gr-S

spore: profile
id: graphite-structural
spore_version: 0.2
family: carbon-materials
name: Structural graphite
abbreviation: Gr-S
role: isostatic and extruded rigid graphite blocks, flexible graphite foil and highly oriented pyrolytic graphite (HOPG), used for heat spreading, seals, bearings, electrodes and high-temperature parts
category: carbon
type: Graphite
summary: |
  Structural graphite is synthetic carbon that has been graphitised above 2,100 °C and then formed into dense blocks or sheets. Isostatically pressed fine-grain grades such as SIGRAFINE R4340 print a bulk density of 1.72 g/cm3, a flexural strength of 45 MPa and a thermal conductivity of 105 W/(m.K) at 20 °C, while Olmec Y450 reaches 1.90 g/cm3 and 80 MPa. Flexible graphite foil (SPREADERSHIELD) spreads heat at 300 to 1500 W/mK in its plane. HOPG is the most ordered form, with a basal conductivity of 1800 W/(m.K) against 8 W/(m.K) across its planes. Pyrolytic graphite (pg) is a different, vapour-deposited form and is covered on its own page.
best_for: Dense, machinable graphite blocks for electrodes, seals, bearings and high-temperature parts, and thin foils that spread heat in one plane
weakest_at: 'Oxidation in air from about 700 °C, and strong anisotropy in foils and HOPG: heat and electricity cross the layers far less well than they travel along them'
identity:
  formula: C
  crystal_system: hexagonal
  space_group: P63/mmc (flat layers) or P63mc (buckled), as printed for graphite
  source: wiki-graphite
  where: Infobox (formula C, hexagonal, space group P63mc or P63/mmc); unit cell a = 2.461 and c = 6.708 Å printed in the same infobox
tags:
  environments: []
  stresses:
    - extreme-heat
  applications:
    - thermal-control
    - mechanisms
    - optics-and-cameras
properties:
  - benchmark: density
    value: 1.72
    unit: g/cm3
    scope: material
    conditions:
      grade: SIGRAFINE R4340, fine-grain, isostatically pressed (continuous casting grade)
      basis: typical average values of different rectangular and round block sizes
    method: Bulk density, DIN IEC 60413/204, as printed
    status: ground
    source: sgl-r4340
    where: Material data table, Bulk density row
  - benchmark: density
    value: 1.83
    unit: g/cm3
    scope: material
    conditions:
      grade: SIGRAFINE R4550, fine-grain, isostatically pressed
      basis: typical average values, as printed
    method: Bulk density, DIN IEC 60413/204
    status: ground
    source: sgl-r4550
    where: Material data table, Bulk density row
  - benchmark: density
    value: 1.9
    unit: g/cm3
    scope: material
    conditions:
      grade: Y450, isostatically moulded fine-grained graphite
      basis: typical values, subject to change without notice (datasheet footnote)
    method: Density column of the isostatic fine-grained graphites table
    status: ground
    source: olmec-fine
    where: Technical Data table, Y450 row, Density column (g/cm3)
  - benchmark: density
    value: 2.27
    unit: g/cm3
    scope: material
    conditions:
      form: HOPG (highly oriented pyrolytic graphite), SPI Supplies brand
      temperature: 300 K
    method: Physical properties table of the SPI technical note
    status: ground
    source: spi-hopg
    where: Table 3, Physical properties (at 300 K), Density row
  - benchmark: flexural_strength
    value: 45
    unit: MPa
    scope: material
    conditions:
      grade: SIGRAFINE R4340, fine-grain, isostatically pressed
      basis: typical average value; test standard DIN IEC 60413/501, temperature not stated
    method: Flexural strength, as printed
    status: ground
    source: sgl-r4340
    where: Material data table, Flexural strength row
  - benchmark: flexural_strength
    value: 60
    unit: MPa
    scope: material
    conditions:
      grade: SIGRAFINE R4550, fine-grain, isostatically pressed
      basis: typical average value; temperature not stated
    method: Flexural strength, as printed
    status: ground
    source: sgl-r4550
    where: Material data table, Flexural strength row
  - benchmark: flexural_strength
    value: 80
    unit: MPa
    scope: material
    conditions:
      grade: Y450, isostatically moulded fine-grained graphite
      basis: typical value; temperature not stated
    method: Flexural Strength column of the Technical Data table
    status: ground
    source: olmec-fine
    where: Technical Data table, Y450 row, Flexural Strength column (MPa)
  - benchmark: compressive_strength
    value: 90
    unit: MPa
    scope: material
    conditions:
      grade: SIGRAFINE R4340, fine-grain, isostatically pressed
      basis: typical average value; test standard DIN 51910
    method: Compressive strength, as printed
    status: ground
    source: sgl-r4340
    where: Material data table, Compressive strength row
  - benchmark: compressive_strength
    value: 160
    unit: MPa
    scope: material
    conditions:
      grade: Y450, isostatically moulded fine-grained graphite
      basis: typical value
    method: Compressive Strength column of the Technical Data table
    status: ground
    source: olmec-fine
    where: Technical Data table, Y450 row, Compressive Strength column (MPa)
  - benchmark: elastic_modulus
    value: 14
    unit: GPa
    scope: material
    conditions:
      grade: Y450, isostatically moulded fine-grained graphite
      basis: Young's modulus column, typical value
    method: Youngs Modulus column of the Technical Data table
    status: ground
    source: olmec-fine
    where: Technical Data table, Y450 row, Youngs Modulus column (GPa)
  - benchmark: thermal_conductivity
    value: 105
    unit: W m-1 K-1
    scope: material
    conditions:
      grade: SIGRAFINE R4340, fine-grain, isostatically pressed
      temperature: 20 °C
    method: DIN 51908, as printed
    status: ground
    source: sgl-r4340
    where: Material data table, Thermal conductivity (20 °C) row
  - benchmark: thermal_conductivity
    value: 125
    unit: W m-1 K-1
    scope: material
    conditions:
      grade: SIGRAFINE R4820, fine-grain, isostatically pressed
      temperature: 20 °C
    method: DIN 51908, as printed
    status: ground
    source: sgl-r4820
    where: Material data table, Thermal conductivity (20 °C) row
  - benchmark: thermal_conductivity
    value: 85
    unit: W/m.K
    scope: material
    conditions:
      grade: Y450, isostatically moulded fine-grained graphite
      temperature: not stated on the datasheet
    method: Thermal Conductivity column of the Technical Data table
    status: ground
    source: olmec-fine
    where: Technical Data table, Y450 row, Thermal Conductivity column (W/m.K)
  - benchmark: thermal_conductivity
    value: 1800
    unit: W/(m·K)
    scope: material
    conditions:
      form: HOPG, SPI Supplies brand
      direction: basal plane (in-plane)
      temperature: 300 K
    method: Physical properties table; the printed tolerance (plus or minus 200) wraps onto a second line in the PDF and is not carried here
    status: ground
    source: spi-hopg
    where: Table 3, Physical properties (at 300 K), Thermal conductivity along the basal plane row
  - benchmark: thermal_conductivity
    value: 8
    unit: W/(m·K)
    scope: material
    conditions:
      form: HOPG, SPI Supplies brand
      direction: perpendicular to the basal plane (through-plane)
      temperature: 300 K
    method: Physical properties table, printed as 8 plus or minus 2
    status: ground
    source: spi-hopg
    where: Table 3, Physical properties (at 300 K), Thermal conductivity perpendicular to the basal plane row
  - benchmark: thermal_conductivity
    value: 300
    value_high: 1500
    unit: W/mK
    scope: material
    conditions:
      product: SPREADERSHIELD flexible graphite heat spreader (NeoGraf)
      direction: in-plane
      basis: product brochure range, not a single grade
    method: Brochure bullet, printed as 300-1500 W/mK in-plane conductivity
    status: ground
    source: surseal-spreadershield
    where: Page 1 bullet list, In-plane conductivity
  - benchmark: electrical_resistivity
    value: 12
    unit: µΩm
    scope: material
    conditions:
      grade: SIGRAFINE R4340, fine-grain, isostatically pressed
      basis: typical average value; test standard DIN IEC 60413/402
    method: Resistivity, as printed
    status: ground
    source: sgl-r4340
    where: Material data table, Resistivity row
  - benchmark: electrical_resistivity
    value: 11
    unit: µΩm
    scope: material
    conditions:
      grade: SIGRAFINE R4820, fine-grain, isostatically pressed
      basis: typical average value; test standard DIN IEC 60413/402
    method: Resistivity, as printed
    status: ground
    source: sgl-r4820
    where: Material data table, Resistivity row
  - benchmark: cte
    value: 3.2
    unit: x10-6 K-1
    scope: material
    conditions:
      grade: SIGRAFINE R4340, fine-grain, isostatically pressed
      temperature: 20 to 200 °C
    method: Thermal expansion, DIN 51909, as printed
    status: ground
    source: sgl-r4340
    where: Material data table, Thermal expansion (20 to 200 °C) row
  - benchmark: cte
    value: 6
    unit: 10-6/ °C
    scope: material
    conditions:
      grade: Y450, isostatically moulded fine-grained graphite
      temperature: not stated on the datasheet
    method: Coefficient of Thermal Expansion column of the Technical Data table
    status: ground
    source: olmec-fine
    where: Technical Data table, Y450 row, Coefficient of Thermal Expansion column
  - benchmark: max_service_temp
    value: 3000
    unit: °C
    scope: material
    conditions:
      grade: isostatic fine-grained graphites (Olmec range)
      basis: datasheet text says the graphites can operate at temperatures approaching 3000 °C; atmosphere not stated
    method: Written statement in the datasheet introduction, not a tested limit
    status: ground
    source: olmec-fine
    where: Introduction text, paragraph beginning With an ability to operate in temperatures approaching 3000°C
  - benchmark: open_porosity
    value: 15
    unit: Vol. %
    scope: material
    conditions:
      grade: SIGRAFINE R4340, fine-grain, isostatically pressed
      basis: typical average value; test standard DIN 66133
    method: Open porosity, as printed
    status: ground
    source: sgl-r4340
    where: Material data table, Open porosity row
  - benchmark: mosaic_spread
    value: 0.4
    unit: degrees
    scope: material
    conditions:
      grade: ZYA (SPI-1), highest-ordered HOPG grade
      tolerance: plus or minus 0.1 degrees, as printed
    method: X-ray mosaic spread, Table 1 of the SPI technical note
    status: ground
    source: spi-hopg
    where: Table 1, Mosaic spread, ZYA and SPI-1 rows
  - benchmark: oxidation_onset_air
    value: 500
    unit: °C
    scope: material
    conditions:
      form: HOPG, SPI Supplies brand
      environment: air
    method: Starts-to-burn temperature in air, as printed in Table 2 of the SPI technical note
    status: ground
    source: spi-hopg
    where: Table 2, Starts to burn temperatures, Air row
  - benchmark: anisotropy_ratio
    value: 300
    unit: '-'
    scope: material
    conditions:
      product: SPREADERSHIELD flexible graphite heat spreader (NeoGraf)
      basis: maximum ratio printed in the brochure, in-plane to through-plane
    method: Brochure bullet, printed as anisotropic ratio up to 300:1
    status: ground
    source: surseal-spreadershield
    where: Page 1 bullet list, Anisotropic ratio
risks:
  hazards:
    - text: Wikipedia gives the OSHA limit for graphite as 15 million particles per cubic foot (1.5 mg/m3) over an 8-hour workday, and the NIOSH recommended limit as 2.5 mg/m3 respirable dust. The page does not separate natural from synthetic graphite.
      ghs: []
      source: wiki-graphite
      where: United States paragraph under occupational safety (Mining section)
    - text: Wikipedia says high dust levels may create a potential for explosion, and that graphite at 1250 mg/m3 is immediately dangerous to life and health.
      ghs: []
      source: wiki-graphite
      where: Occupational safety paragraphs (IDLH and dust explosion statements)
  failure_risks:
    - mode: Oxidation in air at high temperature
      trigger: Air at 700 °C and above (Wikipedia); HOPG starts to burn in air at 500 °C (SPI)
      consequence: Graphite oxidises to carbon dioxide and the surface recedes; the part loses section and strength
      severity: moderate
      source: wiki-graphite
      where: Properties section, statement on oxidation at 700 °C and above
    - mode: Heat trapped across the layers
      trigger: Heat must cross the thickness of a foil or HOPG plate instead of travelling along the plane
      consequence: HOPG conducts 1800 W/(m.K) along its planes but 8 W/(m.K) across them, so a hot spot does not spread through the thickness
      severity: moderate
      source: spi-hopg
      where: Table 3, Physical properties (basal and perpendicular thermal conductivity)
  side_effects:
    - text: 'Electrical conductivity is also strongly directional: conductivity perpendicular to the layers is about 1000 times lower than in the layers (Wikipedia, natural graphite crystal).'
      affects: Designers of electrodes, seals and conductive parts that carry current through the thickness
      source: wiki-graphite
      where: Structure paragraph on electrical conductivity perpendicular to the layers
  handling:
    - text: Keep dust below the NIOSH recommended limit of 2.5 mg/m3 respirable dust, with local exhaust where machining or grinding makes dust (values as printed on Wikipedia).
      source: wiki-graphite
      where: United States paragraph under occupational safety
  mitigations:
    - text: Use the in-plane direction for heat spreading. HOPG measures 1800 W/(m.K) in the basal plane against 8 W/(m.K) across it, so the plate should be oriented with the planes parallel to the heat path.
      source: spi-hopg
      where: Table 3, Physical properties
corrosion:
  - environment: Air at high temperature (oxygen-containing atmosphere)
    headline: Graphite oxidises in air from about 700 °C; HOPG has been reported to burn in air from 500 °C.
    effect: Wikipedia states that in oxygen-containing atmospheres graphite readily oxidises to carbon dioxide at 700 °C and above. The SPI note gives a lower starts-to-burn temperature for HOPG in air (500 °C), and a much higher one under vacuum (2500 °C) or inert gas (3500 °C).
    rating: moderate
    conditions:
      atmosphere: air (oxygen-containing)
      vacuum_or_inert: vacuum at 0.1 torr 2500 °C; nitrogen, argon or helium 3500 °C (HOPG, starts to burn)
    source: wiki-graphite
    where: Properties section, oxidation statement (700 °C and above); SPI Table 2 for the HOPG burn temperatures
  - environment: Oxygen plasma
    headline: HOPG disappears quickly in an oxygen plasma.
    effect: The SPI note states that, apart from some chemicals, the one environment where HOPG will disappear quickly is an oxygen plasma of the type used in its own plasma etcher.
    rating: severe
    conditions:
      environment: oxygen plasma (SPI Plasma Prep II type)
      material: HOPG
    source: spi-hopg
    where: Chemical inertness paragraph
  - environment: Most chemicals at room temperature
    headline: HOPG is chemically inert to almost everything it is tested against, including osmium tetroxide.
    effect: The SPI note reports high chemical inertness and names osmium tetroxide among the reagents it resists. The statement covers HOPG only; isostatic grades were not tested in the sources read.
    rating: low
    conditions:
      material: HOPG
      temperature: not stated
    source: spi-hopg
    where: Chemical inertness paragraph
supply:
  - subject: Synthetic and natural graphite (structural grades are synthetic; flake and lump are mined)
    abundance: The USGS states that the rest of the world's recoverable natural graphite resources exceed 800 million tons. Synthetic production is not quantified in the sources read.
    producers:
      - country: China
        share_percent: 77.8
        year: 2025
      - country: Madagascar
        share_percent: 4.4
        year: 2025
      - country: Brazil
        share_percent: 3.6
        year: 2025
      - country: Mozambique
        share_percent: 3.3
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (graphite listed, for lubricants, batteries and fuel cells)
        listed: true
    recycling: 'USGS: information on the quantity and value of recycled graphite was not available, and the abundance of graphite in the world market inhibits recycling efforts.'
    substitutes:
      - 'USGS: synthetic graphite powder, scrap from machined graphite shapes and calcined petroleum coke compete for iron and steel use; synthetic powder and secondary synthetic graphite from machining compete in battery applications.'
    source: usgs-mcs2026-graphite
    where: World Mine Production and Reserves table, 2025e (world total 1,800,000 t, rounded; shares calculated by Space Mushroom from China 1,400,000 t, Madagascar 80,000 t, Brazil 65,000 t and Mozambique 60,000 t; the USGS text gives China about 82 percent of world production on another basis); Recycling; Substitutes
media: []
documents:
  - title: 'USGS Mineral Commodity Summaries 2026: Graphite (natural)'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-graphite.pdf
    year: 2026
  - title: 'SGL Carbon datasheet: SIGRAFINE R4340 (TDS R4340.00)'
    type: datasheet
    url: https://www.sglgroup.com/data/pdf/SGL-Datasheet-SIGRAFINE-R4340-EN.pdf
    year: 2019
  - title: 'SGL Carbon datasheet: SIGRAFINE R4550'
    type: datasheet
    url: https://www.sglgroup.com/data/pdf/SGL-Datasheet-SIGRAFINE-R4550-EN.pdf
    year: 2019
  - title: 'SGL Carbon datasheet: SIGRAFINE R4820'
    type: datasheet
    url: https://www.sglgroup.com/data/pdf/SGL-Datasheet-SIGRAFINE-R4820-EN.pdf
    year: 2019
  - title: 'Olmec Advanced Materials: Isostatic Fine Grained Graphites technical data'
    type: datasheet
    url: https://www.olmec.co.uk/wp-content/uploads/2026/04/Fine-Grained-Graphites-Datasheet-2026.1V17.pdf
    year: 2026
  - title: 'SPI Supplies: HOPG technical note (revised 2015)'
    type: datasheet
    url: https://www.2spi.com/catalog/documents/TECHNICAL_NOTE_HOPG.pdf
    year: 2015
  - title: NeoGraf SPREADERSHIELD graphite heat spreaders brochure (distributor copy)
    type: datasheet
    url: https://www.sur-seal.com/wp-content/uploads/2022/10/SpreadershieldDataSheet8_Updated_web.pdf
    year: 2022
gaps:
  - No atomic oxygen, thermal-cycling or radiation result for isostatic, extruded or flexible graphite was found in this run. The NASA MISSE 2 report read for pyrolytic graphite (pg) has no row for structural grades.
  - 'CAS number not given: the OSHA chemical data page for graphite (synthetic) returned HTTP 403, and PubChem was not read.'
  - NIOSH Pocket Guide page for graphite returned an empty page; the NIOSH REL (2.5 mg/m3) and IDLH (1250 mg/m3) are taken from Wikipedia, which does not separate natural and synthetic grades.
  - No PubChem GHS classification read in this run, so ghs lists are empty.
  - 'Flexible graphite: only the NeoGraf SPREADERSHIELD brochure was read. Through-plane conductivity, density and the Grafoil (GrafTech) datasheet were not found in this run; the NeoGraf TDS 321 datasheet host did not resolve.'
  - 'Isostatic grades: only three SIGRAFINE grades and one Olmec grade (Y450) were read. Olmec electrical resistivity, porosity and ash were not given for Y450 in the sources read, and the other Olmec grades are not included.'
  - Extruded rigid graphite was not covered by any source read in this run.
  - 'Non-canonical property names used because no canonical name fits: compressive_strength, open_porosity, mosaic_spread, oxidation_onset_air and anisotropy_ratio.'
  - 'HOPG basal conductivity: the PDF prints the tolerance across a line break; only the value 1800 is carried, and the tolerance is noted in method.'
  - Supply shares are calculated from the USGS production table; the USGS text gives China about 82 percent on a different basis. The EU critical raw materials list was not checked for graphite.
  - Wikipedia gives the OSHA limit as 1.5 mg/m3 for graphite without separating natural and synthetic grades; the synthetic-graphite OSHA page (osha.gov/chemicaldata/533) was not readable here.
sources:
  usgs-mcs2026-graphite:
    title: 'USGS Mineral Commodity Summaries 2026: Graphite (natural)'
    id: USGS MCS 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-graphite.pdf
    year: 2026
    kind: report
    license: US government work (cited)
  usgs-critical-2025:
    title: Interior Department releases final 2025 List of Critical Minerals
    id: USGS science snippet
    url: https://www.usgs.gov/news/science-snippet/interior-department-releases-final-2025-list-critical-minerals
    year: 2025
    kind: web
    license: US government work (cited)
  wiki-graphite:
    title: 'Wikipedia: Graphite'
    id: en.wikipedia.org, Graphite
    url: https://en.wikipedia.org/wiki/Graphite
    year: 2026
    kind: web
    license: CC BY-SA 4.0 (cited)
  sgl-r4340:
    title: 'SGL Carbon TDS R4340.00: SIGRAFINE R4340 material data'
    id: TDS R4340.00, 04 2019
    url: https://www.sglgroup.com/data/pdf/SGL-Datasheet-SIGRAFINE-R4340-EN.pdf
    year: 2019
    kind: datasheet
    license: cited
  sgl-r4550:
    title: 'SGL Carbon datasheet: SIGRAFINE R4550 material data'
    id: SIGRAFINE R4550
    url: https://www.sglgroup.com/data/pdf/SGL-Datasheet-SIGRAFINE-R4550-EN.pdf
    year: 2019
    kind: datasheet
    license: cited
  sgl-r4820:
    title: 'SGL Carbon datasheet: SIGRAFINE R4820 material data'
    id: SIGRAFINE R4820
    url: https://www.sglgroup.com/data/pdf/SGL-Datasheet-SIGRAFINE-R4820-EN.pdf
    year: 2019
    kind: datasheet
    license: cited
  olmec-fine:
    title: 'Olmec Advanced Materials: Isostatic Fine Grained Graphites technical data'
    id: Olmec datasheet V17, Fine Grain
    url: https://www.olmec.co.uk/wp-content/uploads/2026/04/Fine-Grained-Graphites-Datasheet-2026.1V17.pdf
    year: 2026
    kind: datasheet
    license: cited
  spi-hopg:
    title: 'SPI Supplies: HOPG technical note'
    id: SPI Supplies technical note, revised 08/31/2015
    url: https://www.2spi.com/catalog/documents/TECHNICAL_NOTE_HOPG.pdf
    year: 2015
    kind: datasheet
    license: cited
  surseal-spreadershield:
    title: NeoGraf SPREADERSHIELD graphite heat spreaders brochure
    id: SPREADERSHIELD, distributor Sur-Seal copy
    url: https://www.sur-seal.com/wp-content/uploads/2022/10/SpreadershieldDataSheet8_Updated_web.pdf
    year: 2022
    kind: datasheet
    license: cited
review:
  status: draft
  method: assistant
  checked_values: 24
  note: Values read by an AI assistant from datasheet PDFs and pages fetched in this run. Structural grades differ from pg (vapour-deposited pyrolytic graphite) and from glassy-carbon (non-graphitising resin carbon) and graphite-anode (battery anode powder).
updated: '2026-10-26'
story:
  recipe:
    line: 'Structural graphite is synthetic carbon that has been graphitised: synthetic graphitisation runs in excess of 2,100 °C (Wikipedia), so the carbon arranges into the layered hexagonal form of graphite. Isostatic grades are pressed in all directions, which gives a homogeneous block that Olmec calls isotropic. HOPG is the most ordered form, with a mosaic spread of 0.4 degrees for its top grade (SPI).'
    parts:
      - name: Carbon
        symbol: C
        share: high purity, synthetic grade (Wikipedia)
        role: The only element. The stacked graphene-like layers give the material its anisotropic conduction, and the grade sets how well the layers line up and how dense the block is.
  risk_groups:
    - title: For people
      level: 0
      verdict: Dust is the main health concern
      lead: Graphite dust is the hazard in handling and machining. Wikipedia gives OSHA and NIOSH limits for graphite, and no GHS classification was read in this run.
      points:
        - label: Dust
          line: The NIOSH recommended limit is 2.5 mg/m3 respirable dust, so machining and grinding need local exhaust.
        - label: Dust explosion
          line: Wikipedia says high dust levels may create a potential for explosion.
    - title: In service
      level: 1
      verdict: Oxidises in air from about 700 °C
      lead: The main service limit is oxidation. Above about 700 °C in air graphite turns into carbon dioxide, and HOPG starts to burn near 500 °C in air.
      points:
        - label: Oxidation
          line: Graphite oxidises to carbon dioxide in oxygen-containing atmospheres at 700 °C and above (Wikipedia).
        - label: HOPG in air
          line: The SPI note gives a starts-to-burn temperature of 500 °C in air, against 2500 °C under vacuum at 0.1 torr.
  why: Structural graphite is a dense, stable carbon that conducts heat well along its planes and can be machined into blocks, electrodes, seals and bearings. SIGRAFINE R4340 prints a bulk density of 1.72 g/cm3 and a thermal conductivity of 105 W/(m.K) at 20 °C, and HOPG reaches 1800 W/(m.K) in its basal plane. Its weak point is oxidation in air above about 700 °C.
  uses:
    - where: Heat spreaders in electronics (flexible graphite foil)
      line: Wikipedia says graphite foil is made into heat sinks for laptop computers, keeping them cool while saving weight. NeoGraf sells SPREADERSHIELD foil with an in-plane conductivity of 300 to 1500 W/mK.
    - where: Air bearings and seals (isostatic fine-grained graphite)
      line: Olmec lists air bearings and seal applications among the industries that use its isostatic fine-grained graphites, and gives Y450 a flexural strength of 80 MPa.
    - where: X-ray monochromators (HOPG)
      line: The SPI note says its ZYA and SPI-1 grades diffract x-rays with higher efficiency than other materials, with intensities up to five times those of lithium fluoride crystals.
    - where: Continuous casting and electrodes (fine-grain isostatic graphite)
      line: SGL lists SIGRAFINE R4340 for continuous casting, and Wikipedia says graphite is widely used as electrodes in high-temperature material processing.
  can_do:
    - label: Heat spreading in the plane
      benchmark: thermal_conductivity
      value: '1800'
      line: HOPG conducts 1800 W/(m.K) along the basal plane, and SPREADERSHIELD foil 300 to 1500 W/mK in-plane.
    - label: Dense block
      benchmark: density
      value: '1.72'
      line: SIGRAFINE R4340 has a bulk density of 1.72 g/cm3, and Y450 reaches 1.90 g/cm3.
    - label: High-temperature operation
      benchmark: max_service_temp
      value: '3000'
      line: Olmec says its isostatic fine-grained graphites can operate at temperatures approaching 3000 °C; the datasheet does not name the atmosphere.
  compare: Structural graphite is a manufactured, dense carbon, unlike pyrolytic graphite (pg), which is vapour-deposited and very anisotropic. Glassy carbon (glassy-carbon) is a non-graphitising resin carbon with no layers, and graphite-anode (graphite-anode) is a powder used in lithium-ion battery anodes. The table compares density, thermal conductivity and resistivity across the grades.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Thermal conductivity
      benchmark: thermal_conductivity
    - label: Electrical resistivity
      benchmark: electrical_resistivity
  handling:
    - Keep graphite dust below the NIOSH limit of 2.5 mg/m3 respirable dust, with local exhaust in machining and grinding.
    - Keep parts below about 500 to 700 °C in air; HOPG starts to burn in air near 500 °C.
    - Orient plates and foils so the planes carry the heat; the through-plane path conducts far less.
  good_for:
    - Dense, machinable blocks for electrodes, seals, bearings and high-temperature parts that must not melt.
    - Thin flexible foil that spreads heat in its plane in electronics.
    - HOPG as an x-ray monochromator or an atomically flat surface.
  watch_out:
    - Oxidation in air from about 700 °C; plan a vacuum or inert atmosphere for hot parts.
    - 'Strong anisotropy: HOPG conducts 1800 W/(m.K) along its planes against 8 W/(m.K) across them.'
    - 'Dust: no atmospheric or orbital erosion result for these grades was found in this run.'
  verdict: Structural graphite is a dense, stable carbon for blocks and foils that spread heat in one plane. It fits electrodes, seals and thermal spreaders in air below about 700 °C, and it is the wrong choice where heat must cross the layers or where oxidation is unprotected.