spore: profile
id: carbon-fibre
spore_version: 0.2
family: carbon-materials
name: Carbon fibre (PAN-based, pitch-based) and carbon/carbon
abbreviation: CF
role: reinforcing fibre
category: composites
type: carbon-fiber-reinforced
summary: |
  Carbon fibre is a filament of mostly carbon, made by carbonising a precursor fibre. The PAN-based grades read here are Teijin Tenax HTA40 and UMS40 and Toray Torayca T700S. Tenax UMS40 is rated at 4700 MPa and 390 GPa along the fibre, and T700S at 4900 MPa and 230 GPa. Mitsubishi's pitch-based K63712 is stiffer, at 92 Msi, but breaks at only 0.4 %. Carbon/carbon, a carbon-fibre composite with a carbon matrix, was used for the Space Shuttle wing leading edge and nose cap, but unprotected material loses weight quickly in air above about 500 C.
best_for: 'Stiffness and strength per unit mass along the fibre: 390 GPa at 1.79 g/cm3 for Tenax UMS40 (datasheet values)'
weakest_at: Oxidation in air above about 500 C when uncoated (NASA), and very low strain to failure in the pitch-based K63712 (0.4 %)
identity:
  formula: Carbon filament, over 99 % carbon for the pitch-based K63712 grade; PAN-based grades are carbonised polyacrylonitrile
  cas: 7782-42-5
  source: toray-t700s
  where: Introduction and Fiber Properties table of the Torayca T700S data sheet (grade and density); CAS number is printed on the Rave high-purity carbon fibre SDS (generic carbon CAS, not a grade-specific number)
  filament_diameter: Tenax HTA40 7.0 um, Torayca T700S 7.0 um, Tenax UMS40 4.9 um, K63712 11 um (datasheet values)
tags:
  environments:
    - re-entry
  stresses:
    - extreme-heat
  applications:
    - structures
    - heat-shields
    - propulsion-and-tanks
properties:
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, Tenax HTA40 E13 3K 200tex fibre
    value: 4100
    unit: MPa
    scope: material
    conditions:
      fibre: Tenax HTA40 E13 3K 200tex (PAN-based), bare filament
      basis: typical value in the product overview
    method: Typical value printed in the Teijin product overview, MPa column (590 ksi printed alongside)
    status: ground
    source: teijin-overview
    where: Product overview table, row HTA40 E13 3K 200tex 15Z, tensile strength columns
  - benchmark: elastic_modulus
    label: Tensile modulus, Tenax HTA40 E13 3K 200tex fibre
    value: 240
    unit: GPa
    scope: material
    conditions:
      fibre: Tenax HTA40 E13 3K 200tex (PAN-based), bare filament
      basis: first printed modulus pair (240 GPa, 35 Msi); a second test method in the same row prints 230 GPa (33 Msi)
    method: Typical value printed in the Teijin product overview; the German product sheet gives 240 GPa for the same grade
    status: ground
    source: teijin-overview
    where: Product overview table, row HTA40 E13 3K 200tex 15Z, modulus columns
  - benchmark: elongation
    label: Elongation at break, Tenax HTA40 E13 3K 200tex fibre
    value: 1.7
    unit: '%'
    scope: material
    conditions:
      fibre: Tenax HTA40 E13 3K 200tex, bare filament
    method: Typical value printed in the Teijin product overview
    status: ground
    source: teijin-overview
    where: Product overview table, row HTA40 E13 3K 200tex 15Z, elongation column
  - benchmark: density
    label: Density, Tenax HTA40 E13 3K 200tex fibre
    value: 1.77
    unit: g/cm3
    scope: material
    conditions:
      fibre: Tenax HTA40 E13 3K 200tex, bare filament
    method: Typical value printed in the Teijin product overview
    status: ground
    source: teijin-overview
    where: Product overview table, row HTA40 E13 3K 200tex 15Z, density column
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, Tenax UMS40 F23 24K 800tex fibre
    value: 4700
    unit: MPa
    scope: material
    conditions:
      fibre: Tenax UMS40 F23 24K 800tex (PAN-based, ultra-high modulus), bare filament
      sizing: S (PU, 1.0 %)
    method: Typical value printed in the Teijin product overview, MPa column (680 ksi printed alongside)
    status: ground
    source: teijin-overview
    where: Product overview table, row UMS40 F23 24K 800tex S, tensile strength columns
  - benchmark: elastic_modulus
    label: Tensile modulus, Tenax UMS40 F23 24K 800tex fibre
    value: 390
    unit: GPa
    scope: material
    conditions:
      fibre: Tenax UMS40 F23 24K 800tex, bare filament
      basis: first printed modulus pair (390 GPa, 57 Msi); the second test method in the same row prints 375 GPa (54 Msi)
    method: Typical value printed in the Teijin product overview; the German product sheet also gives 390 GPa
    status: ground
    source: teijin-overview
    where: Product overview table, row UMS40 F23 24K 800tex S, modulus columns
  - benchmark: elongation
    label: Elongation at break, Tenax UMS40 F23 24K 800tex fibre
    value: 1.2
    unit: '%'
    scope: material
    conditions:
      fibre: Tenax UMS40 F23 24K 800tex, bare filament
    method: Typical value printed in the Teijin product overview
    status: ground
    source: teijin-overview
    where: Product overview table, row UMS40 F23 24K 800tex S, elongation column
  - benchmark: density
    label: Density, Tenax UMS40 F23 24K 800tex fibre
    value: 1.79
    unit: g/cm3
    scope: material
    conditions:
      fibre: Tenax UMS40 F23 24K 800tex, bare filament
    method: Typical value printed in the Teijin product overview
    status: ground
    source: teijin-overview
    where: Product overview table, row UMS40 F23 24K 800tex S, density column
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, Torayca T700S carbon fibre (single fibre)
    value: 4900
    unit: MPa
    scope: material
    conditions:
      fibre: Torayca T700S (PAN-based), 12k and 24k tows, standard modulus
      unit_in_source: 500 kgf/mm2 (printed as 4900 (500) MPa (kgf/mm2))
    method: Nominal value printed in the Toray fibre properties table (test method TY-QA-002)
    status: ground
    source: toray-t700s
    where: Fiber properties table, row Tensile Strength, nominal value
  - benchmark: elastic_modulus
    label: Tensile modulus, Torayca T700S carbon fibre
    value: 230
    unit: GPa
    scope: material
    conditions:
      fibre: Torayca T700S (PAN-based)
      unit_in_source: 23.5 (103 kgf/mm2)
    method: Nominal value printed in the Toray fibre properties table (test method TY-QA-002)
    status: ground
    source: toray-t700s
    where: Fiber properties table, row Tensile Modulus, nominal value
  - benchmark: elongation
    label: Elongation at break, Torayca T700S carbon fibre
    value: 2.1
    unit: '%'
    scope: material
    conditions:
      fibre: Torayca T700S (PAN-based)
    method: Nominal value printed in the Toray fibre properties table (test method TY-QA-002)
    status: ground
    source: toray-t700s
    where: Fiber properties table, row Elongation, nominal value
  - benchmark: density
    label: Density, Torayca T700S carbon fibre
    value: 1.8
    unit: g/cm3
    scope: material
    conditions:
      fibre: Torayca T700S (PAN-based)
    method: Nominal value printed in the Toray fibre properties table (test method TY-QA-003)
    status: ground
    source: toray-t700s
    where: Fiber properties table, row Density, nominal value
  - benchmark: cte
    label: Coefficient of thermal expansion, Torayca T700S carbon fibre
    value: -0.38
    unit: ppm/K
    scope: material
    conditions:
      fibre: Torayca T700S (PAN-based), fibre axis
      unit_in_source: alpha 10-6/C (printed as CTE alpha10-6/C, value -0.38)
    method: Nominal value printed in the Toray functional properties table; 10-6/C equals ppm/K
    status: ground
    source: toray-t700s
    where: Functional properties table, row CTE
  - benchmark: specific_heat
    label: Specific heat, Torayca T700S carbon fibre
    value: 0.18
    unit: Cal/g.°C
    scope: material
    conditions:
      fibre: Torayca T700S (PAN-based)
      unit_in_source: 0.18 Cal/g.C
    method: Printed value in Cal/g.C, converted to J/(kg K) on import (1 cal/(g K) = 4184 J/(kg K))
    status: ground
    source: toray-t700s
    where: Functional properties table, row Specific Heat, nominal value
  - benchmark: thermal_conductivity
    label: Thermal conductivity, Torayca T700S carbon fibre
    value: 9.37
    unit: W/(m·K)
    scope: material
    conditions:
      fibre: Torayca T700S (PAN-based)
      unit_in_source: 0.0224 Cal/cm.S.C
    method: 'Converted by Space Mushroom: 0.0224 cal/(cm s K) times 418.4 gives 9.37 W/(m K); the printed value is 0.0224 Cal/cm.S.C'
    status: ground
    source: toray-t700s
    where: Functional properties table, row Thermal Conductivity, nominal value
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, Torayca T700S in a Toray 2500 epoxy composite
    value: 2550
    unit: MPa
    scope: material
    conditions:
      fibre: Torayca T700S, Toray 2500 resin (120 C cure), normalised to 60 % fibre volume
      temperature: room temperature
      layup: not stated in the datasheet
      unit_in_source: 260 kgf/mm2 (printed as 2550 (260) MPa)
    method: Nominal value printed in the Toray composite properties table; a composite value, not a fibre value
    status: ground
    source: toray-t700s
    where: Composite properties table, row Tensile Strength, footnote on Toray 2500 and 60 % fibre volume
  - benchmark: elastic_modulus
    label: Tensile modulus, Torayca T700S in a Toray 2500 epoxy composite
    value: 135
    unit: GPa
    scope: material
    conditions:
      fibre: Torayca T700S, Toray 2500 resin (120 C cure), normalised to 60 % fibre volume
      temperature: room temperature
    method: Nominal value printed in the Toray composite properties table; a composite value, not a fibre value
    status: ground
    source: toray-t700s
    where: Composite properties table, row Tensile Modulus, footnote as above
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, Mitsubishi K63712 pitch-based fibre
    value: 380
    unit: ksi
    scope: material
    conditions:
      fibre: K63712, coal tar pitch-based carbon fibre, 12k, untwisted
      unit_in_source: 380 ksi
    method: Printed value in ksi, converted to MPa on import (1 ksi = 6.894757 MPa)
    status: ground
    source: mitsubishi-k63712
    where: Typical Properties table, row Tensile Strength
  - benchmark: elastic_modulus
    label: Tensile modulus, Mitsubishi K63712 pitch-based fibre
    value: 92
    unit: Msi
    scope: material
    conditions:
      fibre: K63712, coal tar pitch-based carbon fibre, 12k, untwisted
      unit_in_source: 92 Msi
    method: Printed value in Msi, converted to GPa on import (1 Msi = 6.894757 GPa)
    status: ground
    source: mitsubishi-k63712
    where: Typical Properties table, row Tensile Modulus
  - benchmark: elongation
    label: Ultimate elongation, Mitsubishi K63712 pitch-based fibre
    value: 0.4
    unit: '%'
    scope: material
    conditions:
      fibre: K63712, coal tar pitch-based carbon fibre
    method: Typical value printed in the Mitsubishi Chemical America data sheet
    status: ground
    source: mitsubishi-k63712
    where: Typical Properties table, row Ult Elongation
  - benchmark: density
    label: Density, Mitsubishi K63712 pitch-based fibre
    value: 2.12
    unit: g/cm3
    scope: material
    conditions:
      fibre: K63712, coal tar pitch-based carbon fibre
    method: Typical value printed in the Mitsubishi Chemical America data sheet
    status: ground
    source: mitsubishi-k63712
    where: Typical Properties table, row Density
  - benchmark: thermal_conductivity
    label: Thermal conductivity, Mitsubishi K63712 pitch-based fibre
    value: 140
    unit: W/(m·K)
    scope: material
    conditions:
      fibre: K63712, coal tar pitch-based carbon fibre
    method: Typical value printed in the Mitsubishi Chemical America data sheet
    status: ground
    source: mitsubishi-k63712
    where: Typical Properties table, row Thermal Conductivity
  - benchmark: oxidation_weight_change
    label: Weight change after 0.5 h in air at 500 C, unprotected reinforced carbon/carbon
    value: -2.2
    unit: '%'
    scope: material
    conditions:
      material: RCC-P3 reinforced carbon/carbon, uncoated, small cubes
      atmosphere: 5 torr air
      time: 0.5 h
    method: Weight change printed in NASA oxidation study, Table 2
    status: ground
    source: nasa-rcc-2006
    where: Section 3.1, Table 2, row 500
  - benchmark: oxidation_weight_change
    label: Weight change after 0.5 h in air at 800 C, unprotected reinforced carbon/carbon
    value: -27
    unit: '%'
    scope: material
    conditions:
      material: RCC-P3 reinforced carbon/carbon, uncoated, small cubes
      atmosphere: 5 torr air
      time: 0.5 h
    method: Weight change printed in NASA oxidation study, Table 2
    status: ground
    source: nasa-rcc-2006
    where: Section 3.1, Table 2, row 800
  - benchmark: oxidation_weight_change
    label: Weight change after 0.5 h in air at 1100 C, unprotected reinforced carbon/carbon
    value: -68.6
    unit: '%'
    scope: material
    conditions:
      material: RCC-P3 reinforced carbon/carbon, uncoated, small cubes
      atmosphere: 5 torr air
      time: 0.5 h
    method: Weight change printed in NASA oxidation study, Table 2
    status: ground
    source: nasa-rcc-2006
    where: Section 3.1, Table 2, row 1100
  - benchmark: oxidation_weight_change
    label: Weight change after 1 h in air at 1500 C, SiC-coated reinforced carbon/carbon
    value: -3.34
    unit: '%'
    scope: material
    conditions:
      material: RCC-P3/SiC, SiC conversion coating on all faces, 1.9 cm buttons
      atmosphere: 667 Pa slowly flowing air
      time: 1 h
      uncertainty: plus or minus 0.57 % as printed
    method: Weight change printed in NASA oxidation study, Table 3 (coated specimens at 500 to 1500 C, two per condition)
    status: ground
    source: nasa-rcc-2006
    where: Section 3.2, Table 3, row 1500
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, Tenax UMS45 F22 12K 385tex fibre
    value: 4600
    unit: MPa
    scope: material
    conditions:
      fibre: Tenax UMS45 F22 12K 385tex (PAN-based, ultra-high modulus), bare filament
      sizing: PU, 0.9 %
    method: Typical value printed in the Teijin German product data sheet TSG01de, Zugfestigkeit column (MPa)
    status: ground
    source: teijin-tsg01
    where: Produktdatenblatt table, row UMS45 F22 12K 385tex
  - benchmark: elastic_modulus
    label: Tensile modulus, Tenax UMS45 F22 12K 385tex fibre
    value: 425
    unit: GPa
    scope: material
    conditions:
      fibre: Tenax UMS45 F22 12K 385tex, bare filament
    method: Typical value printed in the Teijin German product data sheet TSG01de, Zug-E-Modul column (GPa); the English overview prints the same 425 GPa
    status: ground
    source: teijin-tsg01
    where: Produktdatenblatt table, row UMS45 F22 12K 385tex
corrosion:
  - environment: Unprotected carbon/carbon in air at 500 to 1100 C (5 torr, 0.5 h)
    headline: Uncoated carbon/carbon loses weight fast in air above 500 C, and most above 800 C.
    effect: Weight change was -2.2 % at 500 C, -27.0 % at 800 C and -68.6 % at 1100 C. The NASA authors describe preferential attack along the fibre edges, and say oxidation begins to be significant above about 500 C.
    rating: severe
    conditions:
      material: RCC-P3 reinforced carbon/carbon, uncoated
      atmosphere: 5 torr air, 0.5 h
    source: nasa-rcc-2006
    where: Abstract; Introduction; Section 3.1, Table 2
  - environment: SiC-coated carbon/carbon in 667 Pa air for 1 h, 500 to 1500 C
    headline: A SiC conversion coating limits weight change, but thermal-expansion cracks let oxygen in.
    effect: Weight change was -0.16 % at 500 C, -0.19 % at 700 C, -0.22 % at 900 C and -3.34 % at 1500 C, with no clear oxidation damage at 500 and 700 C. Carbon and SiC expand at different rates, so through-thickness cracks formed in the coating, and cavities formed under cracks at 1100 and 1300 C.
    rating: moderate
    conditions:
      material: RCC-P3/SiC, coated on all faces
      atmosphere: 667 Pa slowly flowing air, 1 h
    source: nasa-rcc-2006
    where: Section 3.2, Table 3; Introduction on coating cracks
  - environment: Strong oxidisers and peroxides (high-purity carbon fibre thread)
    headline: The SDS warns of violent reactions with strong oxidisers and peroxides.
    effect: The Rave SDS lists strong oxidisers and peroxides as incompatible and says violent reactions may occur. It gives no rating or rate.
    rating: unknown
    conditions:
      product: High purity carbon fibres in carbon fibre threads (SDS product, not a Tenax or Torayca grade)
    source: rave-cf-sds
    where: Sections 10.3 and 10.5
risks:
  hazards:
    - text: PubChem reports that the acrylonitrile monomer used to make PAN fibre is classified as May cause cancer (H350, 99.8 % of reports), Highly flammable (H225, 99.8 %), Toxic in contact with skin (H311, 97.2 %) and Toxic if inhaled (H331, 97.1 %). This describes the precursor monomer, not the finished fibre.
      ghs:
        - 'H350: May cause cancer'
        - 'H225: Highly flammable liquid and vapour'
        - 'H311: Toxic in contact with skin'
        - 'H331: Toxic if inhaled'
      source: pubchem-acrylonitrile
      where: GHS Classification, aggregated reports for CID 7855
    - text: The Rave high-purity carbon fibre SDS says the product is not classified for inhalation, skin, eye, sensitisation, mutagenicity or carcinogenicity. It says inhaling dust may irritate the respiratory system and dust can cause eye irritation.
      ghs: []
      source: rave-cf-sds
      where: Section 11 (toxicological information and symptoms)
  failure_risks:
    - mode: Oxidation of unprotected carbon/carbon in air
      trigger: Heating in air at 800 C for 0.5 h (5 torr)
      consequence: Weight loss of 27.0 % at 800 C and 68.6 % at 1100 C; oxidation attacks the fibres along their edges
      severity: high
      source: nasa-rcc-2006
      where: Section 3.1, Table 2; Abstract
    - mode: Cracking of the SiC oxidation barrier on carbon/carbon
      trigger: Carbon and SiC expand at different rates, so through-thickness cracks form in the coating
      consequence: Oxidation-induced cavities form under cracks at 1100 C and 1300 C; weight change at 1500 C was -3.34 %
      severity: moderate
      source: nasa-rcc-2006
      where: Section 3.2, Table 3; Introduction
    - mode: Violent reaction with strong oxidisers
      trigger: Contact with strong oxidisers or peroxides
      consequence: Violent reactions, according to the SDS
      severity: high
      source: rave-cf-sds
      where: Sections 10.3 and 10.5
  side_effects:
    - text: The Rave SDS says the product is combustible but will not ignite readily. In a fire it releases carbon monoxide and carbon dioxide.
      affects: Fire crew and the enclosure
      source: rave-cf-sds
      where: Sections 5.2 and 9.1 (flammability)
  mitigations:
    - text: A SiC conversion coating held weight change to -0.16 % at 500 C, -0.19 % at 700 C and -0.22 % at 900 C in 1 h at 667 Pa air, with no clear oxidation damage at 500 and 700 C.
      source: nasa-rcc-2006
      where: Section 3.2, Table 3
  handling:
    - text: Store in a cool dry place, away from strong oxidisers and peroxides.
      source: rave-cf-sds
      where: Sections 7.2 and 10.5
    - text: Avoid creating or accumulating dust. Use breathing protection at high dust concentrations, and safety goggles with side protection.
      source: rave-cf-sds
      where: Sections 7 and 8 (control procedures and eye protection)
    - text: Torayca T700S shelf life is 24 months from the month of manufacture if stored under ambient conditions.
      source: toray-t700s
      where: Requirements section
uses:
  - application: heat-shields
    device: Space Shuttle Orbiter wing leading edge and nose cap (reinforced carbon/carbon)
    example: NASA describes reinforced carbon/carbon as the thermal protection of the wing leading edge and nose cap of the Space Shuttle Orbiter.
    source: nasa-rcc-2006
    where: Introduction, first paragraph
  - application: propulsion-and-tanks
    device: Compressed gas storage tanks (natural gas, hydrogen)
    example: Toray says the T700S suits large-scale production, including compressed gas storage tanks for natural gas and hydrogen.
    source: toray-t700s
    where: Introduction paragraph of the data sheet
  - application: structures
    device: Automotive, marine, sports and civil engineering parts
    example: Toray names the T700S as the benchmark for automotive, marine, sports and leisure and civil engineering uses.
    source: toray-t700s
    where: Introduction paragraph of the data sheet
supply:
  - subject: PAN and pitch precursors (carbon fibre feedstock)
    abundance: 'Not applicable: synthetic fibre made from a polymer or pitch precursor; no crustal abundance applies'
    producers: []
    manufacture: Torayca T700S is manufactured in France, Japan, the USA and Korea, according to the Toray data sheet. No production shares by country were read in a fetched source.
    source: toray-t700s
    where: Introduction paragraph of the Torayca T700S data sheet
media: []
documents:
  - title: Torayca T700S Carbon Fiber Data Sheet (Toray Carbon Fibers Europe)
    type: datasheet
    url: https://toray-cfe.com/wp-content/uploads/2025/02/Torayca-T700S-Technical-Data-Sheet.pdf
    year: 2024
  - title: Tenax filament yarn product overview (Teijin Carbon)
    type: datasheet
    url: https://www.teijincarbon.com/fileadmin/user_upload/Datenbl%C3%A4tter/Filament_Yarn/EU_Filament_overview.pdf
    year: 2026
  - title: 'Mitsubishi Chemical America: K63712 coal tar pitch-based carbon fibers, typical properties (hosted by Rockwest Composites)'
    type: datasheet
    url: https://www.rockwestcomposites.com/media/wysiwyg/PD_K63712.pdf
  - title: Oxidation Microstructure Studies of Reinforced Carbon/Carbon (NASA Glenn and Johnson Space Center)
    type: report
    url: https://ntrs.nasa.gov/api/citations/20060005054/downloads/20060005054.pdf
  - title: 'Safety data sheet: High purity carbon fibers in carbon fiber threads, SDS00170CC1016 v4.0 (Rave Scientific)'
    type: sds
    url: https://ravescientific.com/images/pdf/SDS00170CC1016-01_Carbon_Fibre.pdf
    year: 2022
  - title: 'PubChem: Acrylonitrile (CID 7855), GHS classification summary'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/Acrylonitrile
gaps:
  - 'Country production shares for PAN-based and pitch-based carbon fibre: no readable source found, so none are given.'
  - 'Critical-mineral status of acrylonitrile (PAN precursor) and of pitch feedstock: not read.'
  - 'Tenax UMS2526 and Mitsubishi K13C2U (about 900 GPa in trade press): only distributor or trade-press figures found, not a datasheet, so not used.'
  - Tenax HTA40 and UMS40 values come from the Teijin product overview. Its HTA40 row prints a second modulus of 230 GPa for a different test method; this profile uses the first pair (240 GPa).
  - 'Atomic oxygen erosion, UV ageing and thermal-cycling numbers for carbon fibre: not read.'
  - 'Density, thermal conductivity and CTE of carbon/carbon (as a composite): not read. Only weight-change figures from the NASA oxidation study are used.'
  - Filament diameter is not in the property canon, so it is written in identity only. Weight change under oxidation uses the snake_case name oxidation_weight_change, which is not in the canon either.
  - The Rave SDS is for a high-purity carbon fibre thread product (CAS 7782-42-5), not for the Tenax or Torayca production grades. No SDS for a production grade was read.
  - Laminate and composite values for Tenax grades were not read. The Toray 2500 composite rows are for T700S only and are normalised to 60 % fibre volume.
  - Galvanic coupling of carbon fibre with aluminium is covered in the CFRP profile and is not repeated here.
  - 'No media: no image with a checked licence was fetched.'
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 28
  unreachable: 2
  caveats: 4
  note: 'Written by an AI assistant on 2026-10-26 from fetched sources. Unreachable: Teijin standalone HTA40 and UMS fibre data sheets (only the product overview and German sheet were readable); a Mitsubishi K13C2U data sheet. Caveats: UMS40 and HTA40 modulus have two printed test methods; K63712 values converted from ksi and Msi; T700S composite values are composite, not fibre; carbon/carbon values are weight change, not material properties.'
story:
  recipe:
    line: Carbon fibre is made by spinning a precursor into filament, stabilising it and carbonising it to drive off non-carbon elements. For PAN fibre the spun filament is heated to about 300 C in air to oxidise it, then heated in an inert gas to graphitise it (Wikipedia). Pitch-based grades start from coal-tar pitch; K63712 is over 99 % carbon by the Mitsubishi data sheet.
    parts:
      - name: Carbon (element)
        share: over 99 % in the pitch-based K63712 grade (Mitsubishi data sheet); not stated for the PAN-based grades in the sources read
        role: Forms the graphitic filament. The graphitic layers are aligned along the fibre axis, which gives the strength and stiffness per unit mass.
      - name: Polyacrylonitrile (PAN) precursor
        share: the PAN-based grades' precursor share is not stated in the sources read
        role: Spun into filament, oxidised in air at about 300 C, then carbonised. Its oxidation time, temperature and tension set the final properties.
      - name: Coal-tar pitch precursor
        share: the K63712 precursor share is not stated in the sources read
        role: Starting material for the pitch-based high-modulus fibre (Mitsubishi calls K63712 coal tar pitch-based).
  risk_groups:
    - title: For people
      level: 1
      verdict: Dust irritates; acrylonitrile precursor is carcinogenic
      lead: The carbon fibre itself is not classified as hazardous in the SDS read here. Its precursor monomer, acrylonitrile, carries cancer and flammability hazards in PubChem.
      points:
        - label: Dust
          line: Inhaling dust may irritate the respiratory system and dust can cause eye irritation (Rave SDS, section 11). Use goggles and avoid creating dust.
        - label: Precursor monomer
          line: PubChem reports that acrylonitrile is classified as May cause cancer (H350) and Highly flammable (H225) in most reports. The finished fibre is not the monomer.
    - title: If it fails
      lead: The failure modes read here are oxidation in air at high temperature, and violent reactions with strong oxidisers.
      points:
        - label: Air above 500 C
          line: Unprotected carbon/carbon lost 27.0 % of its weight in 0.5 h at 800 C and 68.6 % at 1100 C, in 5 torr air (NASA).
        - label: Coating cracks
          line: A SiC coating limited weight change to -0.22 % at 900 C in 1 h, but cracks from thermal-expansion mismatch let oxygen reach the carbon.
        - label: Oxidisers
          line: The SDS lists violent reactions with strong oxidisers and peroxides.
    - title: Handling and storage
      points:
        - label: Keep it dry and closed
          line: Store in a cool dry place. Torayca T700S shelf life is 24 months from manufacture under ambient conditions.
        - label: Dust
          line: Avoid creating or accumulating dust. Use breathing protection at high dust concentrations.
  why: Carbon fibre combines high stiffness and strength with low density. The PAN-based Tenax UMS40 is rated at 4700 MPa and 390 GPa along the fibre, and the Torayca T700S at 4900 MPa and 230 GPa, both at a density of about 1.8 g/cm3. Mitsubishi's pitch-based K63712 is stiffer still, at 92 Msi, but breaks at only 0.4 % elongation and has a higher density of 2.12 g/cm3. The fibre values are bare-filament datasheet values, not laminate values. In air, the carbon itself is the weak point above about 500 C, which is why carbon/carbon for the Space Shuttle leading edges was used with a SiC coating.
  uses:
    - where: Launcher heat shields
      line: NASA describes reinforced carbon/carbon as the thermal protection of the wing leading edge and nose cap of the Space Shuttle Orbiter. Those parts were exposed to high-temperature air during re-entry.
    - where: Compressed gas tanks
      line: Toray says the T700S suits large-scale production, including compressed gas storage tanks for natural gas and hydrogen.
    - where: Structures
      line: Toray names the T700S as the benchmark for automotive, marine, sports and leisure and civil engineering uses.
  can_do:
    - label: Strength and stiffness
      benchmark: ultimate_tensile_strength
      line: Tenax UMS40 is rated at 4700 MPa in tension along the fibre, and T700S at 4900 MPa. Both are bare-fibre typical or nominal values from the datasheets.
    - label: Thermal conduction
      value: 140 W/(m·K)
      line: The pitch-based K63712 conducts heat at 140 W/(m·K), against 9.37 W/(m·K) for T700S along the fibre (converted from the printed 0.0224 cal/(cm s K)).
    - label: Heat tolerance in carbon/carbon
      value: Oxidises above about 500 C
      line: Unprotected carbon/carbon is limited by air oxidation. The SiC coating in the NASA study held weight change to -0.22 % at 900 C in 1 h at 667 Pa air.
  compare: Along the fibre, the PAN-based grades read here reach 4100 to 4900 MPa and 230 to 390 GPa, with elongation between 1.2 and 2.1 %. The pitch-based K63712 is stiffer (92 Msi) and denser (2.12 g/cm3), and it breaks at only 0.4 %. Carbon/carbon adds heat tolerance but oxidises in air above about 500 C unless it is coated. The table compares the three benchmarks across the PAN and pitch fibres.
  compare_rows:
    - label: Strength along the fibres
      benchmark: ultimate_tensile_strength
    - label: Stiffness along the fibres
      benchmark: elastic_modulus
    - label: Density
      benchmark: density
  handling:
    - Keep it dry and closed, away from strong oxidisers and peroxides.
    - Avoid creating dust. Use goggles and breathing protection at high dust concentrations.
    - Check the safety data sheet of the grade you handle, since the SDS read here is for a thread product.
    - Torayca T700S shelf life is 24 months from manufacture if stored at ambient conditions.
  good_for:
    - 'Stiffness per unit mass along known load paths: Tenax UMS40 reaches 390 GPa at 1.79 g/cm3 (Teijin).'
    - 'High-temperature heat shields, where the carbon is protected from oxygen: carbon/carbon was used for Space Shuttle leading edges (NASA).'
    - 'Compressed gas tanks at high volume: the T700S is produced for that market (Toray).'
  watch_out:
    - Oxidation in air above about 500 C when uncoated (NASA).
    - Very low strain to failure in the pitch-based K63712 (0.4 %).
    - Fibre values are bare-filament values. Laminate strength is lower, so use the CFRP profile for structures.
  verdict: Very stiff and strong along the fibre, and light for what it carries. The fibre is not the limit in air. Oxidation above about 500 C is.
sources:
  toray-t700s:
    title: Torayca T700S Carbon Fiber Data Sheet
    id: Toray Carbon Fibers Europe, commercial documentation AQ. 866-6, July 2024; test methods TY-QA-002, TY-QA-003
    url: https://toray-cfe.com/wp-content/uploads/2025/02/Torayca-T700S-Technical-Data-Sheet.pdf
    year: 2024
    kind: datasheet
    license: manufacturer datasheet, values quoted for reference
  teijin-overview:
    title: 'Product overview: Tenax and Tenax Next filament yarn (Teijin Carbon)'
    id: Teijin Carbon, PDS dated 2026-04-15
    url: https://www.teijincarbon.com/fileadmin/user_upload/Datenbl%C3%A4tter/Filament_Yarn/EU_Filament_overview.pdf
    year: 2026
    kind: datasheet
    license: manufacturer datasheet, values quoted for reference
  teijin-tsg01:
    title: 'Produktdatenblatt: Tenax filament yarn, EU filament (Teijin Carbon Europe)'
    id: Teijin Carbon Europe, product data sheet TSG01de, dated 2025-02-15
    url: https://www.teijincarbon.com/fileadmin/user_upload/Datenbl%C3%A4tter/Filament_Yarn/Product_Data_Sheet_TSG01de__EU_Filament__de____DE_.pdf
    year: 2025
    kind: datasheet
    license: manufacturer datasheet, values quoted for reference
  mitsubishi-k63712:
    title: 'K63712: Coal tar pitch-based carbon fibers, typical properties (Mitsubishi Chemical America)'
    id: Mitsubishi Chemical America data sheet, undated; hosted by Rockwest Composites
    url: https://www.rockwestcomposites.com/media/wysiwyg/PD_K63712.pdf
    kind: datasheet
    license: manufacturer datasheet, values quoted for reference
  nasa-rcc-2006:
    title: Oxidation Microstructure Studies of Reinforced Carbon/Carbon
    id: NASA NTRS 20060005054; N. S. Jacobson (NASA Glenn), D. M. Curry (NASA Johnson Space Center)
    url: https://ntrs.nasa.gov/api/citations/20060005054/downloads/20060005054.pdf
    kind: report
    license: NASA NTRS public document
  rave-cf-sds:
    title: 'Safety data sheet: High purity carbon fibers in carbon fiber threads, SDS00170CC1016 v4.0'
    id: Rave Scientific, Regulation (EC) No 1907/2006 Art. 31, dated October 5th 2022
    url: https://ravescientific.com/images/pdf/SDS00170CC1016-01_Carbon_Fibre.pdf
    year: 2022
    kind: datasheet
    license: supplier safety data sheet, quoted for reference
  pubchem-acrylonitrile:
    title: 'PubChem compound record: Acrylonitrile (CID 7855), GHS classification summary'
    id: CID 7855, National Center for Biotechnology Information
    url: https://pubchem.ncbi.nlm.nih.gov/compound/Acrylonitrile
    kind: database
    license: PubChem public data
  wiki-carbon-fibre:
    title: 'Carbon fibers (Wikipedia article): composition, history and PAN process only'
    id: Wikipedia, article Carbon fibers
    url: https://en.wikipedia.org/wiki/Carbon_fibers
    kind: web
    license: CC BY-SA 4.0