Pyrolytic graphite PG
C · CAS 7440-44-0 · hexagonal, P63mc (buckled) or P63/mmc (flat)
Pyrolytic graphite is a dense, layered carbon made by heating a hydrocarbon gas until it decomposes and the carbon deposits as graphite.
Evidence level
5 of 5
Flown or field-proven
- 0Predicted only. No one has made it, or no measurement exists.
- 1Calculated. Only calculated or predicted values from sources.
- 2Lab-measured. Measured properties with their conditions stated.
- 3Space-relevant tests. Measured in conditions relevant to space, such as vacuum or atomic oxygen.
- 4Ground-qualified. Qualified for an application on the ground.
- 5Flown or field-proven. Flight or field results exist.
Thermal conduction
80
Density
2.25
Orbital survival
4.15e-25
Recipe, share of the weight
- C 100.0%Carbon
Best for
Heat spreading in one direction, where a thin, light carbon layer must carry heat away along its plane
Weakest at
Strong anisotropy: heat conducts poorly across the layers, and the material is costly to make at high temperature
Risk at a glance
- People None found. Dust is the main concern
- If it fails Low. Atomic oxygen erosion in low Earth orbit
- Corrosion Low. In low Earth orbit the erosion yield was 4.15e-25 cm3/atom after an atomic oxygen fluence of 8.43e21 atoms/cm2.
Quick facts: PG
| Property | Value | Basis |
|---|---|---|
| Density | 2.25 g/cm³ | 1 sourced value |
| Young's modulus | 4.8 GPa | 1 sourced value |
| Thermal conductivity | 10 to 1,700 W/(m·K) | 2 sourced values across conditions |
| Thermal expansion (CTE) | 0.6 to 4.3 ppm/K | 1 sourced value |
| Melting point | 3,650 °C | 1 sourced value |
| Specific heat | 712 J/(kg·K) | 1 sourced value |
| Electrical resistivity | 0.000014 Ω·m | 1 sourced value |
What is the density of Pyrolytic graphite (PG)?
Pyrolytic graphite (PG) has a density of 2.25 g/cm³. The source and test conditions are listed in the properties table on this page.
What is the thermal conductivity of Pyrolytic graphite (PG)?
Pyrolytic graphite (PG) has a thermal conductivity of 10 to 1,700 W/(m·K). The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the coefficient of thermal expansion of Pyrolytic graphite (PG)?
Pyrolytic graphite (PG) has a coefficient of thermal expansion of 0.6 to 4.3 ppm/K. The source and test conditions are listed in the properties table on this page.
What is the melting point of Pyrolytic graphite (PG)?
Pyrolytic graphite (PG) has a melting point of 3,650 °C. The source and test conditions are listed in the properties table on this page.
What is the Young's modulus of Pyrolytic graphite (PG)?
Pyrolytic graphite (PG) has a Young's modulus of 4.8 GPa. The source and test conditions are listed in the properties table on this page.
Why it exists
Pyrolytic graphite is a layered carbon whose heat conduction is far higher along its planes than across them. It combines a density of 2.25 g/cm3 with a specific heat of 712 J K-1 kg-1 at room temperature, so it stores and spreads heat efficiently in one direction. Its atomic oxygen erosion in low Earth orbit was measured on NASA's MISSE 2 tray.
Where it's used
Heat spreading in electronics
A secondary article describes pyrolytic graphite as having a basal-plane conductivity up to 1700 W/mK. The same article says it has found use in high-performance, niche aerospace applications.
Thermal link in cryogenic systems
A 2017 study of pyrolytic graphite sheet measured its low-temperature transport properties and describes it as a light, highly conducting thermal link over a wide temperature range.
Atomic-oxygen exposure in low Earth orbit
NASA flew pyrolytic graphite on the MISSE 2 tray outside the ISS airlock, with an erosion yield of 4.15e-25 cm3/atom.
Recipe
C
Pyrolytic graphite is pure carbon. It is made by heating a hydrocarbon gas nearly to its decomposition temperature so that the carbon deposits as graphite, the layered hexagonal form of carbon.
| Ingredient | Atoms per unit | Share of the weight | What it does |
|---|---|---|---|
| Carbon C | 1 | 100.0% | The only element in the material. Carbon atoms form flat hexagonal sheets, and the sheets stack into the layered structure that makes conduction strongly directional. |
Weight shares are calculated from standard atomic weights.
What it can do
Thermal conduction
80
measured
A datasheet quotes thermal conductivity of 80 to 240 W m-1 K-1 at 0 to 100 °C for a commercial pyrolytic graphite disc. A secondary source quotes up to 1700 W/mK in the basal plane and 10 W/mK across it.
Density
2.25
measured
The datasheet density is 2.25 g/cm3 at 20 °C.
Orbital survival
4.15e-25
measured
On MISSE 2 it recorded 4.15e-25 cm3/atom after about 4 years in low Earth orbit, and the NASA predictive tool estimated 3.73e-25 cm3/atom.
How it compares
Pyrolytic graphite is a dense, thermally anisotropic carbon. Its in-plane conductivity is far higher than most materials in this collection, but across the layers it is much lower, so it suits in-plane heat spreading. The table compares it with other materials on conductivity, density and the orbital erosion measurement.
The same measurements for each material, so you can compare them. Each row names the key condition under the value; the full conditions and methods are in the numbered notes under Technical details. Other materials are shown beside it; each was measured under its own conditions, so open its page before comparing closely. Compare every grade in the family.
| Measurement | PG | Gr-S | GC |
|---|---|---|---|
| Thermal behavior and safety | |||
| Thermal conductivity | 80 W m-1 K-14 | 105 W m-1 K-1 | 4.6 W/(K.m) |
| Thermal conductivity | 1700 W/mK5 | 105 W m-1 K-1 | 4.6 W/(K.m) |
| Thermal conductivity | 10 W/mK6 | 105 W m-1 K-1 | 4.6 W/(K.m) |
| specific heatDatasheet value | 712 J K-1 kg-1 | no data | no data |
| melting pointDatasheet value | 3650 °C | no data | no data |
| Physical and electrical | |||
| Density | 2.25 g cm-33 | 1.72 g/cm³ | 1.54 g/cm³ |
| electrical resistivityDatasheet value | 1375 µOhm cm | 12 µΩm | 50 ohm µm |
| Other measurements | |||
| Atomic oxygen erosion | 4.15×10^-25 cm³/atom1 | no data | no data |
| Atomic oxygen erosion | 3.73×10^-25 cm³/atom2 | no data | no data |
| Thermal expansion (CTE) | 0.6 x10-6 K-17 | 3.2 x10-6 K-1 | 2.5 x10-6 K-1 |
| elastic modulusDatasheet value, as printed | 4.8 GPa | 14 GPa | 35 kN/mm2 |
| osha pel respirable | 5 mg/m38 | no data | no data |
Why choose it, and why not
Good for
- In-plane heat spreading, where a light, thin carbon layer carries heat along its plane.
- Carbon flown on NASA's MISSE 2 tray, with a documented erosion yield for low Earth orbit.
Watch out for
- Strong anisotropy: 1700 W/mK in the basal plane against 10 W/mK across it, so it is a poor through-thickness conductor.
- Costly to make, because the deposition needs very high temperatures; a secondary article says so without giving a process value.
Pyrolytic graphite is a directional heat spreader with a measured orbital erosion yield. It is the right choice when heat must travel in one plane, and the wrong choice when it must cross the layers.
Technical details
For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Atomic oxygen erosion | Measured mass loss from the flown sample, reported as erosion yield by NASA | exposure MISSE 2 PEACE tray outside the ISS Quest airlock, 2001 to 2005atomic oxygen fluence 8.43e21 atoms/cm2environment low Earth orbit | — |
| 2 | Atomic oxygen erosion | Value from the NASA predictive tool, shown next to the flown result for comparison | exposure predicted for the same MISSE 2 exposureatomic oxygen fluence 8.43e21 atoms/cm2 | — |
| 3 | Density | Datasheet value for a commercial pyrolytic graphite disc | temperature 20 °Cgrade pyrolytic graphite disc, 99.99% purity, as rolled | — |
| 4 | Thermal conductivity | Datasheet range printed as 80-240 W m-1 K-1 at 0-100 °C | temperature 0 to 100 °Cgrade commercial pyrolytic graphite disc (direction not stated on the page) | — |
| 5 | Thermal conductivity | Upper value quoted for in-plane conductivity in a secondary article; not a measured result in this profile | direction basal plane (in-plane)form pyrolytic graphite, formed from the gas phase | — |
| 6 | Thermal conductivity | Value quoted in the same secondary article as the basal-plane figure | direction perpendicular to the basal plane (through-plane)form pyrolytic graphite | — |
| 7 | Thermal expansion (CTE) | Datasheet range, printed as 0.6-4.3 x10-6 K-1 at 0-100 °C | temperature 0 to 100 °Cgrade pyrolytic graphite disc | — |
| 8 | osha pel respirable | Regulatory limit as printed on the OSHA chemical data page | basis OSHA permissible exposure limit, time-weighted average, respirable fraction, for graphite (synthetic) CAS 7440-44-0 | — |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Atomic oxygen in low Earth orbit (MISSE 2 PEACE tray, ISS) | low | In low Earth orbit the erosion yield was 4.15e-25 cm3/atom after an atomic oxygen fluence of 8.43e21 atoms/cm2.1 |
| Thermal cycling in the MISSE 2 tray | low | The flight tray was not reported to have failed under thermal cycling, but the report gives no separate result for pyrolytic graphite.2 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Atomic oxygen in low Earth orbit (MISSE 2 PEACE tray, ISS) | NASA flew pyrolytic graphite on the MISSE 2 PEACE tray and measured its erosion yield. The predictive tool, which fits the MISSE 2 data, estimated 3.73e-25 cm3/atom, so the flown and predicted values agree to within about 11%. The report also lists atomic oxygen fluence as the controlling exposure. | exposure outside the Quest airlock of the ISS, 2001 to 2005fluence 8.43e21 atoms/cm2duration about 3.95 years (MISSE 2 PEACE exposure) |
| 2 | Thermal cycling in the MISSE 2 tray | No separate thermal-cycling result for pyrolytic graphite was found in the source. The nominal base-plate range was -30 to 40 °C; this is a condition of the exposure, not a measured effect on PG. | range nominal base-plate range, -30 to 40 °Cmaterial pyrolytic graphite on the MISSE 2 PEACE tray |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
Pyrolytic graphite is a carbon material with OSHA exposure limits for graphite dust. No hazard classification was read in this run.
- Dust
- OSHA sets a limit of 15 mg/m3 for total dust and 5 mg/m3 for respirable dust for synthetic graphite, so machining and grinding need dust control.
- Natural graphite
- For natural graphite, NIOSH sets a respirable REL of 2.5 mg/m3 and an IDLH of 1250 mg/m3.
In orbit
The orbital data concern the surface, not the health of people.
- Atomic oxygen
- On the MISSE 2 tray the erosion yield was 4.15e-25 cm3/atom, with an atomic oxygen fluence of 8.43e21 atoms/cm2.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Atomic oxygen erosion in low Earth orbitlow severity | Exposure to atomic oxygen, at a fluence of 8.43e21 atoms/cm2 over about 4 years on MISSE 2Surface recession of 4.15e-25 cm3/atom erosion yield (the flown value), which the predictive tool estimated at 3.73e-25 cm3/atom. |
Side effects on surrounding parts
| Affects | Effect |
|---|---|
| Designers who assume isotropic conduction | The thermal conductivity is anisotropic, about 1700 W/mK in the basal plane against 10 W/mK across it, so a pyrolytic graphite part works as a heat spreader in its plane, not as a through-thickness conductor. |
Handling and storage
- Dust control: the OSHA limits for graphite are 15 mg/m3 total dust and 5 mg/m3 respirable fraction (synthetic), so use local exhaust where machining or grinding makes dust.
Mitigations
- Use the in-plane direction for heat spreading and do not rely on through-plane conduction; the NASA erosion test shows that the flown sample survived atomic oxygen with a yield of 4.15e-25 cm3/atom.
Supply and geography
How common the raw materials are and where they come from.
Natural graphite (mine feedstock; pyrolytic graphite itself is made from a hydrocarbon gas)
Not quantified for pyrolytic graphite. The USGS world resources of graphite are described as exceeding 800 million tons of recoverable graphite outside the United States.
- Top producers (2025)
- China 77.8%, Madagascar 4.4%, Brazil 3.6%, Mozambique 3.3%
- Critical mineral lists
- US: listed, EU: not listed
- 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 and secondary synthetic graphite from machined shapes compete for battery applications.
Documents
Datasheets, safety data sheets, papers and standards you can open.
Full record
The complete spore, as stored. Free to reuse under CC-BY-4.0. Images keep the licence shown with each one.
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spore: profile
id: pg
spore_version: 0.2
family: carbon-materials
name: Pyrolytic graphite
abbreviation: PG
role: thermally anisotropic carbon, deposited from hydrocarbon gas and used for heat spreading and atomic-oxygen tests in orbit
category: carbon
type: Graphite
summary: |
Pyrolytic graphite is a dense, layered carbon made by heating a hydrocarbon gas until it decomposes and the carbon deposits as graphite. Its heat conduction is strongly directional: a datasheet quotes thermal conductivity of 80 to 240 W/m K at 0 to 100 °C, while a secondary source quotes up to 1700 W/mK in the basal plane and 10 W/mK across it. In low Earth orbit on NASA's MISSE 2 tray, its atomic oxygen erosion yield was 4.15e-25 cm3/atom, a value that the predictive tool estimated at 3.73e-25 cm3/atom.
best_for: Heat spreading in one direction, where a thin, light carbon layer must carry heat away along its plane
weakest_at: 'Strong anisotropy: heat conducts poorly across the layers, and the material is costly to make at high temperature'
identity:
formula: C
cas: 7440-44-0
crystal_system: hexagonal
space_group: P63mc (buckled) or P63/mmc (flat)
source: wiki-graphite
where: Infobox (formula C, hexagonal or rhombohedral, space group P63mc or P63/mmc); CAS 7440-44-0 from the OSHA chemical data page for graphite (synthetic)
tags:
environments:
- low-earth-orbit
stresses:
- atomic-oxygen
applications:
- thermal-control
properties:
- benchmark: atomic_oxygen_erosion_yield
value: 4.15e-25
unit: cm3/atom
scope: material
conditions:
exposure: MISSE 2 PEACE tray outside the ISS Quest airlock, 2001 to 2005
atomic_oxygen_fluence: 8.43e21 atoms/cm2
environment: low Earth orbit
method: Measured mass loss from the flown sample, reported as erosion yield by NASA
status: flight
source: nasa-ao-2008
where: Table I, MISSE 2 PEACE polymers erosion yield data (pyrolytic graphite row); repeated in the measured table, MISSE 2 column
- benchmark: atomic_oxygen_erosion_yield
value: 3.73e-25
unit: cm3/atom
scope: material
conditions:
exposure: predicted for the same MISSE 2 exposure
atomic_oxygen_fluence: 8.43e21 atoms/cm2
method: Value from the NASA predictive tool, shown next to the flown result for comparison
status: calculated
source: nasa-ao-2008
where: Measured atomic oxygen erosion yields table, Predicted column (pyrolytic graphite row)
- benchmark: density
value: 2.25
unit: g cm-3
scope: material
conditions:
temperature: 20 °C
grade: pyrolytic graphite disc, 99.99% purity, as rolled
method: Datasheet value for a commercial pyrolytic graphite disc
status: ground
source: goodfellow-pg
where: Physical properties, Density (product page for pyrolitic graphite disc)
- benchmark: thermal_conductivity
value: 80
value_high: 240
unit: W m-1 K-1
scope: material
conditions:
temperature: 0 to 100 °C
grade: commercial pyrolytic graphite disc (direction not stated on the page)
method: Datasheet range printed as 80-240 W m-1 K-1 at 0-100 °C
status: ground
source: goodfellow-pg
where: Thermal properties, Thermal conductivity (pyrolitic graphite disc)
- benchmark: thermal_conductivity
value: 1700
unit: W/mK
scope: material
conditions:
direction: basal plane (in-plane)
form: pyrolytic graphite, formed from the gas phase
method: Upper value quoted for in-plane conductivity in a secondary article; not a measured result in this profile
status: ground
source: electronics-cooling
where: Article text on pyrolytic graphite, basal-plane thermal conductivity
- benchmark: thermal_conductivity
value: 10
unit: W/mK
scope: material
conditions:
direction: perpendicular to the basal plane (through-plane)
form: pyrolytic graphite
method: Value quoted in the same secondary article as the basal-plane figure
status: ground
source: electronics-cooling
where: Article text on pyrolytic graphite, perpendicular conductivity
- benchmark: specific_heat
value: 712
unit: J K-1 kg-1
scope: material
conditions:
temperature: 25 °C
grade: pyrolytic graphite disc
method: Datasheet value
status: ground
source: goodfellow-pg
where: Thermal properties, Specific heat (pyrolitic graphite disc)
- benchmark: cte
value: 0.6
value_high: 4.3
unit: x10-6 K-1
scope: material
conditions:
temperature: 0 to 100 °C
grade: pyrolytic graphite disc
method: Datasheet range, printed as 0.6-4.3 x10-6 K-1 at 0-100 °C
status: ground
source: goodfellow-pg
where: Thermal properties, Coefficient of thermal expansion
- benchmark: melting_point
value: 3650
unit: °C
scope: material
conditions:
grade: pyrolytic graphite disc
method: Datasheet value
status: ground
source: goodfellow-pg
where: Thermal properties, Melting point
- benchmark: electrical_resistivity
value: 1375
unit: µOhm cm
scope: material
conditions:
temperature: 0 °C
grade: pyrolytic graphite disc
method: Datasheet value
status: ground
source: goodfellow-pg
where: Electrical properties, Electrical resistivity
- benchmark: elastic_modulus
value: 4.8
unit: GPa
scope: material
conditions:
basis: tensile modulus; the datasheet states no test condition
grade: pyrolytic graphite disc
method: Datasheet value, as printed
status: ground
source: goodfellow-pg
where: Mechanical properties, Tensile modulus
- benchmark: osha_pel_respirable
value: 5
unit: mg/m3
scope: material
conditions:
basis: OSHA permissible exposure limit, time-weighted average, respirable fraction, for graphite (synthetic) CAS 7440-44-0
method: Regulatory limit as printed on the OSHA chemical data page
status: ground
source: osha-synthetic
where: Exposure limits, OSHA PEL-TWA (15 mg/m3 total dust, 5 mg/m3 respirable fraction)
risks:
hazards:
- text: Dust is the hazard listed for graphite. OSHA sets a PEL-TWA of 15 mg/m3 total dust and 5 mg/m3 respirable fraction for graphite (synthetic); the NIOSH REL is not given there.
ghs: []
source: osha-synthetic
where: Exposure limits
- text: For natural graphite, OSHA lists a PEL of 15 mppcf, NIOSH a REL of 2.5 mg/m3 (respirable) and an IDLH of 1250 mg/m3. Pyrolytic graphite is not the natural mineral, so these limits are a guide for handling dust.
ghs: []
source: osha-natural
where: Exposure limits (CAS 7782-42-5)
failure_risks:
- mode: Atomic oxygen erosion in low Earth orbit
trigger: Exposure to atomic oxygen, at a fluence of 8.43e21 atoms/cm2 over about 4 years on MISSE 2
consequence: Surface recession of 4.15e-25 cm3/atom erosion yield (the flown value), which the predictive tool estimated at 3.73e-25 cm3/atom.
severity: low
source: nasa-ao-2008
where: Table I and measured table, MISSE 2 PEACE
side_effects:
- text: The thermal conductivity is anisotropic, about 1700 W/mK in the basal plane against 10 W/mK across it, so a pyrolytic graphite part works as a heat spreader in its plane, not as a through-thickness conductor.
affects: Designers who assume isotropic conduction
source: electronics-cooling
where: Article text on basal-plane and perpendicular conductivity
handling:
- text: 'Dust control: the OSHA limits for graphite are 15 mg/m3 total dust and 5 mg/m3 respirable fraction (synthetic), so use local exhaust where machining or grinding makes dust.'
source: osha-synthetic
where: Exposure limits
mitigations:
- text: Use the in-plane direction for heat spreading and do not rely on through-plane conduction; the NASA erosion test shows that the flown sample survived atomic oxygen with a yield of 4.15e-25 cm3/atom.
source: nasa-ao-2008
where: Table I
corrosion:
- environment: Atomic oxygen in low Earth orbit (MISSE 2 PEACE tray, ISS)
headline: In low Earth orbit the erosion yield was 4.15e-25 cm3/atom after an atomic oxygen fluence of 8.43e21 atoms/cm2.
effect: NASA flew pyrolytic graphite on the MISSE 2 PEACE tray and measured its erosion yield. The predictive tool, which fits the MISSE 2 data, estimated 3.73e-25 cm3/atom, so the flown and predicted values agree to within about 11%. The report also lists atomic oxygen fluence as the controlling exposure.
rating: low
conditions:
exposure: outside the Quest airlock of the ISS, 2001 to 2005
fluence: 8.43e21 atoms/cm2
duration: about 3.95 years (MISSE 2 PEACE exposure)
source: nasa-ao-2008
where: Table I; Measured atomic oxygen erosion yields table; section 2.1 exposure details
- environment: Thermal cycling in the MISSE 2 tray
headline: The flight tray was not reported to have failed under thermal cycling, but the report gives no separate result for pyrolytic graphite.
effect: No separate thermal-cycling result for pyrolytic graphite was found in the source. The nominal base-plate range was -30 to 40 °C; this is a condition of the exposure, not a measured effect on PG.
rating: low
conditions:
range: nominal base-plate range, -30 to 40 °C
material: pyrolytic graphite on the MISSE 2 PEACE tray
source: nasa-ao-2008
where: Section 2.1 exposure details
supply:
- subject: Natural graphite (mine feedstock; pyrolytic graphite itself is made from a hydrocarbon gas)
abundance: Not quantified for pyrolytic graphite. The USGS world resources of graphite are described as exceeding 800 million tons of recoverable graphite outside the United States.
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 (final, published 6 November 2025)
listed: true
- list: EU critical raw materials list
listed: false
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 and secondary synthetic graphite from machined shapes compete for battery applications.'
source: usgs-mcs2026-graphite
where: 'World Mine Production and Reserves table, 2025e (1,800,000 t world total, rounded; shares calculated by Space Mushroom from the printed production figures: China 1,400,000 t, Madagascar 80,000 t, Brazil 65,000 t, Mozambique 60,000 t); Recycling; Substitutes; critical list from usgs-critical-2025'
media: []
documents:
- title: 'NASA/TM-2008-215490: Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit'
type: report
url: https://ntrs.nasa.gov/citations/20090011780
year: 2008
- title: 'USGS Mineral Commodity Summaries 2026: Graphite (natural)'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-graphite.pdf
year: 2026
- title: 'Goodfellow: Pyrolytic Graphite Carbon Disk (product and datasheet page)'
type: datasheet
url: https://www.goodfellow.com/usa/pyrolytic-graphite-disc-group
year: 2026
- title: Low temperature transport properties of pyrolytic graphite sheet (arXiv:1704.03204)
type: paper
url: https://arxiv.org/pdf/1704.03204
year: 2017
- title: 'OSHA chemical data: Graphite (synthetic), CAS 7440-44-0'
type: standard
url: https://www.osha.gov/chemicaldata/533
year: 2021
- title: 'OSHA chemical data: Graphite (natural), respirable fraction, CAS 7782-42-5'
type: standard
url: https://www.osha.gov/chemicaldata/665
year: 2021
gaps:
- No flight result for pyrolytic graphite beyond MISSE 2 erosion yield; no thermal-vacuum, radiation or UV exposure result found for pyrolytic graphite.
- The atomic oxygen erosion yield is not a canonical property name, so it is written as atomic_oxygen_erosion_yield.
- PubChem GHS classification could not be read in this run (the page returned a browser check), so no GHS entry is given.
- NIOSH Pocket Guide entry for graphite (natural) was not reached; the limits come from the OSHA chemical data pages.
- The 1700 W/mK and 10 W/mK values come from a secondary article, not from a manufacturer datasheet; the MINTEQ Pyroid datasheet returned HTTP 403.
- The pyrolytic graphite sheet arXiv paper gives thickness and temperature ranges but no thermal conductivity or density values for pyrolytic graphite, so it is cited for the thermal-link use only.
- Pyrolytic-graphite-specific supply is not quantified; the supply shares are for natural graphite, the mine feedstock, not for pyrolytic deposition.
- The Wikipedia Pyrolytic carbon article gives no density or thermal conductivity number and no deposition temperature for manufacture.
sources:
nasa-ao-2008:
title: Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit
id: NASA/TM-2008-215490 (Banks, Backus and de Groh, December 2008)
url: https://ntrs.nasa.gov/citations/20090011780
year: 2008
kind: report
license: NASA public domain (cited)
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, 14 November 2025
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)
goodfellow-pg:
title: 'Goodfellow: Pyrolytic Graphite Carbon Disk, 99.99% purity, product datasheet'
id: Goodfellow Metals, grade Pyrolitic Graphite, SKU 1000037214-group
url: https://www.goodfellow.com/usa/pyrolytic-graphite-disc-group
year: 2026
kind: datasheet
license: Goodfellow terms (cited)
electronics-cooling:
title: 'Electronics Cooling: thermal management article on pyrolytic graphite sheet'
id: electronics-cooling.com, article p=218
url: https://www.electronics-cooling.com/?p=218
year: 2026
kind: web
license: cited
arxiv-pgs-2017:
title: Low temperature transport properties of pyrolytic graphite sheet
id: arXiv:1704.03204 (Nakamura, Miyafuji, Fujii, Matsui, Fukuyama)
url: https://arxiv.org/pdf/1704.03204
year: 2017
kind: paper
license: arXiv (cited)
wiki-pyrolytic-carbon:
title: 'Wikipedia: Pyrolytic carbon'
id: en.wikipedia.org, Pyrolytic_carbon
url: https://en.wikipedia.org/wiki/Pyrolytic_carbon
year: 2026
kind: web
license: CC BY-SA 4.0 (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)
wiki-carbon:
title: 'Wikipedia: Carbon'
id: en.wikipedia.org, Carbon (standard atomic weight from CIAAW 2021)
url: https://en.wikipedia.org/wiki/Carbon
year: 2026
kind: web
license: CC BY-SA 4.0 (cited)
osha-synthetic:
title: 'OSHA chemical data: Graphite (synthetic)'
id: CAS 7440-44-0, OSHA chemical sampling data
url: https://www.osha.gov/chemicaldata/533
year: 2021
kind: standard
license: US government work (cited)
osha-natural:
title: 'OSHA chemical data: Graphite (natural), respirable fraction'
id: CAS 7782-42-5, OSHA chemical sampling data
url: https://www.osha.gov/chemicaldata/665
year: 2021
kind: standard
license: US government work (cited)
review:
status: draft
method: assistant
checked_values: 12
note: Values read by an AI assistant from pages fetched in this run; the MISSE 2 flight record and the Goodfellow datasheet are the primary values.
story:
recipe:
line: Pyrolytic graphite is pure carbon. It is made by heating a hydrocarbon gas nearly to its decomposition temperature so that the carbon deposits as graphite, the layered hexagonal form of carbon.
parts:
- name: Carbon
symbol: C
atoms: 1
atomic_weight: 12.011
role: The only element in the material. Carbon atoms form flat hexagonal sheets, and the sheets stack into the layered structure that makes conduction strongly directional.
risk_groups:
- title: For people
level: 0
verdict: Dust is the main concern
lead: Pyrolytic graphite is a carbon material with OSHA exposure limits for graphite dust. No hazard classification was read in this run.
points:
- label: Dust
line: OSHA sets a limit of 15 mg/m3 for total dust and 5 mg/m3 for respirable dust for synthetic graphite, so machining and grinding need dust control.
- label: Natural graphite
line: For natural graphite, NIOSH sets a respirable REL of 2.5 mg/m3 and an IDLH of 1250 mg/m3.
- title: In orbit
lead: The orbital data concern the surface, not the health of people.
points:
- label: Atomic oxygen
line: On the MISSE 2 tray the erosion yield was 4.15e-25 cm3/atom, with an atomic oxygen fluence of 8.43e21 atoms/cm2.
why: Pyrolytic graphite is a layered carbon whose heat conduction is far higher along its planes than across them. It combines a density of 2.25 g/cm3 with a specific heat of 712 J K-1 kg-1 at room temperature, so it stores and spreads heat efficiently in one direction. Its atomic oxygen erosion in low Earth orbit was measured on NASA's MISSE 2 tray.
uses:
- where: Heat spreading in electronics
line: A secondary article describes pyrolytic graphite as having a basal-plane conductivity up to 1700 W/mK. The same article says it has found use in high-performance, niche aerospace applications.
- where: Thermal link in cryogenic systems
line: A 2017 study of pyrolytic graphite sheet measured its low-temperature transport properties and describes it as a light, highly conducting thermal link over a wide temperature range.
- where: Atomic-oxygen exposure in low Earth orbit
line: NASA flew pyrolytic graphite on the MISSE 2 tray outside the ISS airlock, with an erosion yield of 4.15e-25 cm3/atom.
can_do:
- label: Thermal conduction
benchmark: thermal_conductivity
value: '80'
line: A datasheet quotes thermal conductivity of 80 to 240 W m-1 K-1 at 0 to 100 °C for a commercial pyrolytic graphite disc. A secondary source quotes up to 1700 W/mK in the basal plane and 10 W/mK across it.
- label: Density
benchmark: density
value: '2.25'
line: The datasheet density is 2.25 g/cm3 at 20 °C.
- label: Orbital survival
benchmark: atomic_oxygen_erosion_yield
value: '4.15e-25'
line: On MISSE 2 it recorded 4.15e-25 cm3/atom after about 4 years in low Earth orbit, and the NASA predictive tool estimated 3.73e-25 cm3/atom.
compare: Pyrolytic graphite is a dense, thermally anisotropic carbon. Its in-plane conductivity is far higher than most materials in this collection, but across the layers it is much lower, so it suits in-plane heat spreading. The table compares it with other materials on conductivity, density and the orbital erosion measurement.
compare_rows:
- label: Thermal conductivity
benchmark: thermal_conductivity
- label: Density
benchmark: density
- label: Atomic oxygen erosion yield
benchmark: atomic_oxygen_erosion_yield
handling:
- 'Dust is the hazard for graphite: keep dust below the OSHA limits with local exhaust in machining and grinding.'
- Use the material in its plane for heat spreading; it conducts far less across the layers.
- In low Earth orbit the surface recedes by atomic oxygen erosion, at 4.15e-25 cm3/atom on MISSE 2.
good_for:
- In-plane heat spreading, where a light, thin carbon layer carries heat along its plane.
- Carbon flown on NASA's MISSE 2 tray, with a documented erosion yield for low Earth orbit.
watch_out:
- 'Strong anisotropy: 1700 W/mK in the basal plane against 10 W/mK across it, so it is a poor through-thickness conductor.'
- Costly to make, because the deposition needs very high temperatures; a secondary article says so without giving a process value.
verdict: Pyrolytic graphite is a directional heat spreader with a measured orbital erosion yield. It is the right choice when heat must travel in one plane, and the wrong choice when it must cross the layers.
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.
| # | Source | Type | Year | Used for |
|---|---|---|---|---|
| Atomic Oxygen Erosion Yield Predictive Tool for Spacecraft Polymers in Low Earth Orbit | report | 2008 | 6 values | |
| USGS Mineral Commodity Summaries 2026: Graphite (natural) | report | 2026 | 1 value | |
| Interior Department releases final 2025 List of Critical Minerals | web | 2025 | 0 values | |
| Goodfellow: Pyrolytic Graphite Carbon Disk, 99.99% purity, product datasheet | datasheet | 2026 | 7 values | |
| Electronics Cooling: thermal management article on pyrolytic graphite sheet | web | 2026 | 3 values | |
| Low temperature transport properties of pyrolytic graphite sheet | paper | 2017 | 0 values | |
| Wikipedia: Pyrolytic carbon | web | 2026 | 0 values | |
| Wikipedia: Graphite | web | 2026 | 1 value | |
| Wikipedia: Carbon | web | 2026 | 0 values | |
| OSHA chemical data: Graphite (synthetic) | standard | 2021 | 3 values | |
| OSHA chemical data: Graphite (natural), respirable fraction | standard | 2021 | 1 value |