{ "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.\n", "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", "designations": [], "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, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "density", "value": 1.83, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "density", "value": 1.9, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "density", "value": 2.27, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "flexural_strength", "value": 45, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "flexural_strength", "value": 60, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "flexural_strength", "value": 80, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "compressive_strength", "value": 90, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "compressive_strength", "value": 160, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "elastic_modulus", "value": 14, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "thermal_conductivity", "value": 105, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "thermal_conductivity", "value": 125, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "thermal_conductivity", "value": 85, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "thermal_conductivity", "value": 1800, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "thermal_conductivity", "value": 8, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "thermal_conductivity", "value": 300, "value_high": 1500, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "electrical_resistivity", "value": 12, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "electrical_resistivity", "value": 11, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "cte", "value": 3.2, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "cte", "value": 6, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "max_service_temp", "value": 3000, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "open_porosity", "value": 15, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "mosaic_spread", "value": 0.4, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "oxidation_onset_air", "value": 500, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "anisotropy_ratio", "value": 300, "bound": "exact", "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", "source_detail": { "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" } } ], "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" } ], "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" } ] }, "uses": [], "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." ], "story": { "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", "line": "HOPG conducts 1800 W/(m.K) along the basal plane, and SPREADERSHIELD foil 300 to 1500 W/mK in-plane.", "benchmark": "thermal_conductivity", "scope": "material", "value": "1800" }, { "label": "Dense block", "line": "SIGRAFINE R4340 has a bulk density of 1.72 g/cm3, and Y450 reaches 1.90 g/cm3.", "benchmark": "density", "scope": "material", "value": "1.72" }, { "label": "High-temperature operation", "line": "Olmec says its isostatic fine-grained graphites can operate at temperatures approaching 3000 °C; the datasheet does not name the atmosphere.", "benchmark": "max_service_temp", "scope": "material", "value": "3000" } ], "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", "scope": "material" }, { "label": "Thermal conductivity", "benchmark": "thermal_conductivity", "scope": "material" }, { "label": "Electrical resistivity", "benchmark": "electrical_resistivity", "scope": "material" } ], "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.", "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", "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", "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." } ], "level": 0, "verdict": "Dust is the main health concern" }, { "title": "In service", "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." } ], "level": 1, "verdict": "Oxidises in air from about 700 °C" } ] }, "updated": "2026-10-26", "review": { "status": "draft", "method": "assistant", "checked_values": 24, "unreachable": 0, "caveats": 0, "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)." }, "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" } }, "license": "CC-BY-4.0", "url": "https://spacemushroom.com/profiles/graphite-structural/" }