{
  "spore": "profile",
  "id": "reinforced-carbon-carbon",
  "spore_version": "0.2",
  "family": "carbon-carbon",
  "name": "Reinforced carbon-carbon (RCC)",
  "abbreviation": "RCC",
  "role": "Oxidation-protected carbon composite for the hottest leading edges and nose cap of the Space Shuttle orbiter",
  "category": "carbon",
  "type": "carbon-carbon",
  "summary": "Reinforced carbon-carbon (RCC) is a carbon-fibre composite in a carbon matrix, with a silicon carbide (SiC) outer coating that resists oxidation. NASA's oxidation study of the orbiter's RCC gives a multi-mission design maximum of 1811 K (2800 °F). In arc-jet tests the SiC coating showed negligible recession below 1967 K (3080 °F). Flown RCC kept a higher surface emittance than virgin RCC at 2040 to 2050 K, per NASA TP-3293.\n",
  "best_for": "Leading edges and nose caps that must reject re-entry heat at surface temperatures up to 1811 K (2800 °F), the NASA multi-mission design maximum",
  "weakest_at": "Oxidation of the carbon substrate once the SiC coating is breached; the substrate's strength loss sets the mission life (NASA TM-104792)",
  "identity": {
    "formula": "Carbon-fibre reinforcement in a carbon (graphite) matrix, with an outer SiC coating, TEOS-derived SiO2 impregnation and a sodium silicate / SiC surface sealant (Type A); no single chemical formula",
    "designations": [],
    "source": "nasa-tm104792",
    "where": "Introduction (three-step oxidation protection: SiC coating, TEOS impregnation, Type A sealant); composition of carbon fibre in a graphite matrix from wikipedia-rcc"
  },
  "tags": {
    "environments": [
      "re-entry"
    ],
    "stresses": [
      "extreme-heat",
      "thermal-cycling"
    ],
    "applications": [
      "heat-shields",
      "structures",
      "thermal-control"
    ]
  },
  "properties": [
    {
      "benchmark": "density",
      "label": "Density, RCC carbon substrate",
      "value": 1.362,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "part": "carbon-carbon substrate of RCC (TEOS-impregnated, before coating)",
        "unit_in_source": "gm/cm 3",
        "use": "substrate density used by the report in its recession analysis"
      },
      "method": "Value printed in the text of the oxidation study and in Table B 1 (Carbon Substrate); Table B 1 footnote 6 cites a personal communication from LTV Corp. (1987), not a measurement in the report",
      "status": "ground",
      "source": "nasa-tm104792",
      "where": "Oxidation Tests, Substrate recession paragraph; Appendix B, Table B 1 (Carbon Substrate)",
      "source_detail": {
        "title": "Analysis of the Shuttle Orbiter Reinforced Carbon-Carbon Oxidation Protection System (NASA TM-104792; S. D. Williams, D. M. Curry, D. Chao, V. T. Pham)",
        "id": "NASA TM-104792; NTRS 19940030739; N94-35245",
        "url": "https://ntrs.nasa.gov/api/citations/19940030739/downloads/19940030739.pdf",
        "year": 1994,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "density",
      "label": "Density, RCC silicon carbide coating",
      "value": 2.114,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "part": "SiC outer coating of RCC",
        "unit_in_source": "gm/cm 3"
      },
      "method": "Value printed in the text of the oxidation study and in Table B 1 (Silicon Carbide Coating); Table B 1 footnote 3 cites a personal communication",
      "status": "ground",
      "source": "nasa-tm104792",
      "where": "Oxidation Tests, Coating Recession paragraph; Appendix B, Table B 1 (Silicon Carbide Coating)",
      "source_detail": {
        "title": "Analysis of the Shuttle Orbiter Reinforced Carbon-Carbon Oxidation Protection System (NASA TM-104792; S. D. Williams, D. M. Curry, D. Chao, V. T. Pham)",
        "id": "NASA TM-104792; NTRS 19940030739; N94-35245",
        "url": "https://ntrs.nasa.gov/api/citations/19940030739/downloads/19940030739.pdf",
        "year": 1994,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "density",
      "label": "Density, RCC Type A surface sealant",
      "value": 1.73,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "part": "Type A surface sealant (sodium silicate and SiC mixture)",
        "unit_in_source": "gm/cm 3"
      },
      "method": "Value printed in the text of the oxidation study and in Table B 1 (Type A Sealant); Table B 1 footnote 3 cites a personal communication",
      "status": "ground",
      "source": "nasa-tm104792",
      "where": "Oxidation Tests, Sealant Loss paragraph; Appendix B, Table B 1 (Type A Sealant)",
      "source_detail": {
        "title": "Analysis of the Shuttle Orbiter Reinforced Carbon-Carbon Oxidation Protection System (NASA TM-104792; S. D. Williams, D. M. Curry, D. Chao, V. T. Pham)",
        "id": "NASA TM-104792; NTRS 19940030739; N94-35245",
        "url": "https://ntrs.nasa.gov/api/citations/19940030739/downloads/19940030739.pdf",
        "year": 1994,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "specific_heat",
      "label": "Specific heat, RCC carbon substrate at 1922 K",
      "value": 0.42,
      "bound": "exact",
      "unit": "cal/(g·K)",
      "scope": "material",
      "conditions": {
        "part": "carbon-carbon substrate",
        "temperature": "1922 K",
        "unit_in_source": "cal/gm-K"
      },
      "method": "Tabulated value printed in Appendix B, Table B 1 (Carbon Substrate); footnote 6 cites a personal communication",
      "status": "ground",
      "source": "nasa-tm104792",
      "where": "Appendix B, Table B 1, Carbon Substrate specific heat column, row 1922 K",
      "source_detail": {
        "title": "Analysis of the Shuttle Orbiter Reinforced Carbon-Carbon Oxidation Protection System (NASA TM-104792; S. D. Williams, D. M. Curry, D. Chao, V. T. Pham)",
        "id": "NASA TM-104792; NTRS 19940030739; N94-35245",
        "url": "https://ntrs.nasa.gov/api/citations/19940030739/downloads/19940030739.pdf",
        "year": 1994,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, RCC carbon substrate, normal column at 311 K",
      "value": 0.12815,
      "bound": "exact",
      "unit": "cal/(cm·s·K)",
      "scope": "material",
      "conditions": {
        "part": "carbon-carbon substrate",
        "temperature": "311 K",
        "direction": "normal column of the source table (direction as labelled there)",
        "unit_in_source": "cal/cm-sec-K"
      },
      "method": "Tabulated value printed in Appendix B, Table B 1 (Carbon Substrate); footnote 6 cites a personal communication",
      "status": "ground",
      "note": "Same table gives 0.19991 cal/(cm·s·K) in the parallel column at the same temperature.",
      "source": "nasa-tm104792",
      "where": "Appendix B, Table B 1, Carbon Substrate conductivity table, normal column, row 311 K",
      "source_detail": {
        "title": "Analysis of the Shuttle Orbiter Reinforced Carbon-Carbon Oxidation Protection System (NASA TM-104792; S. D. Williams, D. M. Curry, D. Chao, V. T. Pham)",
        "id": "NASA TM-104792; NTRS 19940030739; N94-35245",
        "url": "https://ntrs.nasa.gov/api/citations/19940030739/downloads/19940030739.pdf",
        "year": 1994,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, RCC carbon substrate, parallel column at 311 K",
      "value": 0.19991,
      "bound": "exact",
      "unit": "cal/(cm·s·K)",
      "scope": "material",
      "conditions": {
        "part": "carbon-carbon substrate",
        "temperature": "311 K",
        "direction": "parallel column of the source table (direction as labelled there)",
        "unit_in_source": "cal/cm-sec-K"
      },
      "method": "Tabulated value printed in Appendix B, Table B 1 (Carbon Substrate); footnote 6 cites a personal communication",
      "status": "ground",
      "note": "Same table gives 0.12815 cal/(cm·s·K) in the normal column at the same temperature.",
      "source": "nasa-tm104792",
      "where": "Appendix B, Table B 1, Carbon Substrate conductivity table, parallel column, row 311 K",
      "source_detail": {
        "title": "Analysis of the Shuttle Orbiter Reinforced Carbon-Carbon Oxidation Protection System (NASA TM-104792; S. D. Williams, D. M. Curry, D. Chao, V. T. Pham)",
        "id": "NASA TM-104792; NTRS 19940030739; N94-35245",
        "url": "https://ntrs.nasa.gov/api/citations/19940030739/downloads/19940030739.pdf",
        "year": 1994,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "max_service_temp",
      "label": "Original multi-mission maximum temperature of RCC",
      "value": 1811,
      "bound": "exact",
      "unit": "K",
      "scope": "material",
      "conditions": {
        "basis": "design value for nominal multi-mission capability",
        "unit_in_source": "1811 K (2800°F)"
      },
      "method": "Design maximum stated in the introduction of the oxidation study; not a measured failure temperature",
      "status": "ground",
      "note": "The report says extended abort and flight envelopes can give RCC surface temperatures above 2088 K (3300 °F), which causes recession.",
      "source": "nasa-tm104792",
      "where": "Introduction, paragraph 3",
      "source_detail": {
        "title": "Analysis of the Shuttle Orbiter Reinforced Carbon-Carbon Oxidation Protection System (NASA TM-104792; S. D. Williams, D. M. Curry, D. Chao, V. T. Pham)",
        "id": "NASA TM-104792; NTRS 19940030739; N94-35245",
        "url": "https://ntrs.nasa.gov/api/citations/19940030739/downloads/19940030739.pdf",
        "year": 1994,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "sic_recession_onset_temp",
      "label": "SiC coating recession below which recession is negligible (arc-jet)",
      "value": 1967,
      "bound": "upper",
      "unit": "K",
      "scope": "material",
      "conditions": {
        "test": "arc-jet over-temperature tests in air (23% O2 and 77% N2 by mass)",
        "unit_in_source": "1967 K (3080°F)"
      },
      "method": "Threshold read from the over-temperature test results; the report says recession is negligible below this temperature and rises steadily above it",
      "status": "ground",
      "source": "nasa-tm104792",
      "where": "Oxidation Tests, Over-Temperature Test Results; Coating Recession paragraph",
      "source_detail": {
        "title": "Analysis of the Shuttle Orbiter Reinforced Carbon-Carbon Oxidation Protection System (NASA TM-104792; S. D. Williams, D. M. Curry, D. Chao, V. T. Pham)",
        "id": "NASA TM-104792; NTRS 19940030739; N94-35245",
        "url": "https://ntrs.nasa.gov/api/citations/19940030739/downloads/19940030739.pdf",
        "year": 1994,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "sic_erosion_onset_temp",
      "label": "SiC coating erosion becomes diffusion-limited at a constant rate (arc-jet)",
      "value": 2136,
      "bound": "exact",
      "unit": "K",
      "scope": "material",
      "conditions": {
        "test": "arc-jet over-temperature tests in air",
        "unit_in_source": "2136 K (3385°F)"
      },
      "method": "Temperature at which the report observes a constant recession rate independent of surface temperature",
      "status": "ground",
      "source": "nasa-tm104792",
      "where": "Over-Temperature Test Results; Coating Recession paragraph",
      "source_detail": {
        "title": "Analysis of the Shuttle Orbiter Reinforced Carbon-Carbon Oxidation Protection System (NASA TM-104792; S. D. Williams, D. M. Curry, D. Chao, V. T. Pham)",
        "id": "NASA TM-104792; NTRS 19940030739; N94-35245",
        "url": "https://ntrs.nasa.gov/api/citations/19940030739/downloads/19940030739.pdf",
        "year": 1994,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "active_oxidation_onset_temp",
      "label": "Temperature at which SiO gas formation sharply increases (approximate, arc-jet)",
      "value": 2061,
      "bound": "exact",
      "unit": "K",
      "scope": "material",
      "conditions": {
        "test": "arc-jet over-temperature tests in air",
        "unit_in_source": "approximately 2061 K (3250°F)"
      },
      "method": "Read from the report's description of the oxidation mechanism; the report says bubbles erupt and the SiC coating is breached at this temperature",
      "status": "ground",
      "source": "nasa-tm104792",
      "where": "Over-Temperature Test Results, oxidation mechanisms paragraph",
      "source_detail": {
        "title": "Analysis of the Shuttle Orbiter Reinforced Carbon-Carbon Oxidation Protection System (NASA TM-104792; S. D. Williams, D. M. Curry, D. Chao, V. T. Pham)",
        "id": "NASA TM-104792; NTRS 19940030739; N94-35245",
        "url": "https://ntrs.nasa.gov/api/citations/19940030739/downloads/19940030739.pdf",
        "year": 1994,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "total_normal_emittance",
      "label": "Total normal emittance, virgin RCC with SiC coating, room temperature",
      "value": 0.847,
      "value_high": 0.858,
      "bound": "range",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "surface": "virgin RCC with SiC coating, samples 4 and 5 (0.847 and 0.858 respectively)",
        "temperature": "room temperature"
      },
      "method": "Total normal emittance integrated from spectral data at room temperature, as printed in the report",
      "status": "ground",
      "source": "nasa-tp3293",
      "where": "Test Results, Room Temperature Reflectance Data, total normal emittance paragraph",
      "source_detail": {
        "title": "Emittance Measurements of Space Shuttle Orbiter Reinforced Carbon-Carbon (NASA Technical Paper 3293; J. M. Caram, S. A. Bouslog, G. R. Cunnington Jr.)",
        "id": "NASA TP-3293; NTRS 19930006341",
        "url": "https://ntrs.nasa.gov/api/citations/19930006341/downloads/19930006341.pdf",
        "year": 1992,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "total_normal_emittance",
      "label": "Total normal emittance, virgin RCC with SiC coating at 1205 K",
      "value": 0.89,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "surface": "virgin RCC with SiC coating",
        "temperature": "1205.0 K"
      },
      "method": "Value printed in Table 11 (Composite Total Normal Emittance for RCC), virgin column",
      "status": "ground",
      "note": "The conclusions give 0.89 at 1200 K for the low end of the range, so the table temperature and the text temperature differ by 5 K.",
      "source": "nasa-tp3293",
      "where": "Table 11, Virgin column, row 1205.0 K",
      "source_detail": {
        "title": "Emittance Measurements of Space Shuttle Orbiter Reinforced Carbon-Carbon (NASA Technical Paper 3293; J. M. Caram, S. A. Bouslog, G. R. Cunnington Jr.)",
        "id": "NASA TP-3293; NTRS 19930006341",
        "url": "https://ntrs.nasa.gov/api/citations/19930006341/downloads/19930006341.pdf",
        "year": 1992,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "total_normal_emittance",
      "label": "Total normal emittance, virgin RCC with SiC coating at 2040 K",
      "value": 0.63,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "surface": "virgin RCC with SiC coating",
        "temperature": "2040.0 K"
      },
      "method": "Value printed in Table 11 (Composite Total Normal Emittance for RCC), virgin column",
      "status": "ground",
      "note": "The text gives 0.63 for virgin samples at 2050 K, so the table and the text temperatures differ by 10 K.",
      "source": "nasa-tp3293",
      "where": "Table 11, Virgin column, row 2040.0 K; High Temperature Total Normal and Total Hemispherical Emittance paragraph",
      "source_detail": {
        "title": "Emittance Measurements of Space Shuttle Orbiter Reinforced Carbon-Carbon (NASA Technical Paper 3293; J. M. Caram, S. A. Bouslog, G. R. Cunnington Jr.)",
        "id": "NASA TP-3293; NTRS 19930006341",
        "url": "https://ntrs.nasa.gov/api/citations/19930006341/downloads/19930006341.pdf",
        "year": 1992,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "total_normal_emittance",
      "label": "Total normal emittance, flown RCC inner surface, average over test range",
      "value": 0.76,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "surface": "inner surface of RCC flown on orbiter T-seal (sample 1 and 2)",
        "temperature": "about 1200 K to 2050 K (text says essentially independent of temperature)"
      },
      "method": "Average value printed in the high-temperature total emittance paragraph",
      "status": "flight",
      "source": "nasa-tp3293",
      "where": "High Temperature Total Normal and Total Hemispherical Emittance paragraph (inner surface)",
      "source_detail": {
        "title": "Emittance Measurements of Space Shuttle Orbiter Reinforced Carbon-Carbon (NASA Technical Paper 3293; J. M. Caram, S. A. Bouslog, G. R. Cunnington Jr.)",
        "id": "NASA TP-3293; NTRS 19930006341",
        "url": "https://ntrs.nasa.gov/api/citations/19930006341/downloads/19930006341.pdf",
        "year": 1992,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "total_normal_emittance",
      "label": "Total normal emittance, flown RCC outer surface at 2050 K",
      "value": 0.74,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "surface": "outer surface of RCC flown on orbiter T-seal",
        "temperature": "2050.0 K"
      },
      "method": "Value printed in Table 11, Flown Outer column; the text gives 0.75 at 2050 K",
      "status": "flight",
      "note": "Table 11 lists 0.740 at 2050.0 K and the text gives 0.75 at 2050 K for the same flown outer surface; both are printed in the source.",
      "source": "nasa-tp3293",
      "where": "Table 11, Flown Outer column, row 2050.0 K; High Temperature Total Normal paragraph (text value 0.75)",
      "source_detail": {
        "title": "Emittance Measurements of Space Shuttle Orbiter Reinforced Carbon-Carbon (NASA Technical Paper 3293; J. M. Caram, S. A. Bouslog, G. R. Cunnington Jr.)",
        "id": "NASA TP-3293; NTRS 19930006341",
        "url": "https://ntrs.nasa.gov/api/citations/19930006341/downloads/19930006341.pdf",
        "year": 1992,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "total_normal_emittance",
      "label": "Total normal emittance, flown RCC at room temperature",
      "value": 0.856,
      "value_high": 0.857,
      "bound": "range",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "surface": "outer and inner surfaces of flown RCC (0.856 and 0.857 respectively)",
        "temperature": "room temperature"
      },
      "method": "Total normal emittance integrated from room-temperature spectral data, as printed in the report",
      "status": "flight",
      "source": "nasa-tp3293",
      "where": "Test Results, Room Temperature Reflectance Data, total normal emittance paragraph (flown samples)",
      "source_detail": {
        "title": "Emittance Measurements of Space Shuttle Orbiter Reinforced Carbon-Carbon (NASA Technical Paper 3293; J. M. Caram, S. A. Bouslog, G. R. Cunnington Jr.)",
        "id": "NASA TP-3293; NTRS 19930006341",
        "url": "https://ntrs.nasa.gov/api/citations/19930006341/downloads/19930006341.pdf",
        "year": 1992,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "coating_thickness",
      "label": "Typical thickness of the SiC coating on RCC",
      "value": 0.051,
      "value_high": 0.1,
      "bound": "range",
      "unit": "cm",
      "scope": "material",
      "conditions": {
        "part": "SiC coating on RCC",
        "unit_in_source": "0.051cm and 0.1 cm"
      },
      "method": "Typical range printed in the text of the emittance report",
      "status": "ground",
      "source": "nasa-tp3293",
      "where": "High Temperature Total Normal and Total Hemispherical Emittance paragraph (inner surface of flown specimen)",
      "source_detail": {
        "title": "Emittance Measurements of Space Shuttle Orbiter Reinforced Carbon-Carbon (NASA Technical Paper 3293; J. M. Caram, S. A. Bouslog, G. R. Cunnington Jr.)",
        "id": "NASA TP-3293; NTRS 19930006341",
        "url": "https://ntrs.nasa.gov/api/citations/19930006341/downloads/19930006341.pdf",
        "year": 1992,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "mission_limit",
      "label": "Mission limit, hottest RCC leading-edge panels",
      "value": 50,
      "bound": "exact",
      "unit": "missions",
      "scope": "material",
      "conditions": {
        "component": "hottest leading-edge panels",
        "basis": "empirical correlation of calculated mass loss with strength reduction"
      },
      "method": "Operating limit stated by NASA Glenn; the feature says it was set from correlations, not a single test",
      "status": "calculated",
      "source": "nasa-glenn-2005",
      "where": "Paragraph beginning 'For safe operation'",
      "source_detail": {
        "title": "As-Fabricated Reinforced Carbon/Carbon Characterized (NASA Glenn; N. S. Jacobson, A. M. Calomino, N. Webster)",
        "id": "NTRS 20050217101",
        "url": "https://ntrs.nasa.gov/api/citations/20050217101/downloads/20050217101.pdf",
        "year": 2005,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "flight_exposure",
      "label": "Flight exposure of leading-edge RCC available for strength assessment",
      "value": 30,
      "bound": "exact",
      "unit": "missions",
      "scope": "material",
      "conditions": {
        "component": "leading-edge RCC panels",
        "basis": "actual flight exposure, not a test value"
      },
      "method": "Stated in the 2005 NASA Glenn feature as the exposure of material now available for testing",
      "status": "flight",
      "source": "nasa-glenn-2005",
      "where": "Paragraph beginning 'As part of the Return To Flight efforts'",
      "source_detail": {
        "title": "As-Fabricated Reinforced Carbon/Carbon Characterized (NASA Glenn; N. S. Jacobson, A. M. Calomino, N. Webster)",
        "id": "NTRS 20050217101",
        "url": "https://ntrs.nasa.gov/api/citations/20050217101/downloads/20050217101.pdf",
        "year": 2005,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "flight_exposure",
      "label": "Flight exposure of the T-seal samples used for emittance tests",
      "value": 9,
      "bound": "exact",
      "unit": "missions",
      "scope": "material",
      "conditions": {
        "component": "right-side wing panel 17 T-seal of orbiter Atlantis, stagnation region",
        "basis": "flight history of the sample source"
      },
      "method": "Stated in the test sample description of the emittance report",
      "status": "flight",
      "source": "nasa-tp3293",
      "where": "Test Samples section",
      "source_detail": {
        "title": "Emittance Measurements of Space Shuttle Orbiter Reinforced Carbon-Carbon (NASA Technical Paper 3293; J. M. Caram, S. A. Bouslog, G. R. Cunnington Jr.)",
        "id": "NASA TP-3293; NTRS 19930006341",
        "url": "https://ntrs.nasa.gov/api/citations/19930006341/downloads/19930006341.pdf",
        "year": 1992,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Arc-jet air at 1533 to 1811 K (2300 to 2800 °F) with stagnation pressures of 0.01 to 0.07 atm (Double Type A tests)",
      "headline": "Surface sealant is lost first; the study found no substrate oxidation under these conditions.",
      "effect": "Sealant loss followed an Arrhenius-type rate that depended on stagnation pressure, and the report gives fitted coefficients for it. Cross-sections of the double Type A specimens showed no substrate oxidation, so the measured mass loss was taken as sealant (Na2SiO3) loss only. The report also says RCC loses mass over an extended temperature range without apparent surface recession.",
      "rating": "moderate",
      "conditions": {
        "gas": "23% O2 and 77% N2 by mass",
        "specimens": "7.1 cm diameter 19-ply RCC discs with TEOS and double Type A sealant",
        "test": "constant surface temperature heating cycles"
      },
      "source": "nasa-tm104792",
      "where": "Double Type A Tests; Equation 1 and Table II; Introduction"
    },
    {
      "environment": "Arc-jet air at 1967 to 2136 K (3080 to 3385 °F) in over-temperature tests",
      "headline": "SiC coating recession starts above about 1967 K and becomes diffusion-limited at 2136 K.",
      "effect": "Recession is negligible below 1967 K (3080 °F), rises steadily from 1967 K to 2136 K, and is constant at 2136 K (3385 °F). Near 2061 K (3250 °F), SiO gas forms at the SiO2 to SiC interface, bubbles erupt and the coating breaches, exposing the carbon substrate to active oxidation.",
      "rating": "severe",
      "conditions": {
        "test": "arc-jet over-temperature tests, 1867 K to 2136 K surface temperature",
        "specimens": "SiC-coated, TEOS-impregnated RCC discs"
      },
      "source": "nasa-tm104792",
      "where": "Over-Temperature Test Results; Figures 5, 7 and 9"
    },
    {
      "environment": "Re-entry on the wing leading edge (panel 9): nominal and heavyweight entries, and an abort entry, predicted by correlation",
      "headline": "Sealant loss is predicted in flight; SiC recession is predicted to be minimal for routine entries.",
      "effect": "The correlations predict that about 2 mil of surface sealant is removed in about 9 heavyweight or 12 nominal entries. The report says Columbia showed local sealant loss after 12 flights, which agrees with the prediction. Predicted SiC recession is minimal, which the report links to a passive SiC oxidation state during entry. In a single-engine-out abort the sealant is ablated but recession is very small, and refurbishing is needed before the next flight.",
      "rating": "moderate",
      "conditions": {
        "basis": "correlation predictions for nominal, heavyweight and abort trajectories, with a post-flight check on Columbia"
      },
      "source": "nasa-tm104792",
      "where": "Flight Predictions; Table IV"
    },
    {
      "environment": "Orbiter service: hottest leading-edge panels after repeated flights",
      "headline": "The hottest leading-edge panels are limited to 50 missions because of carbon oxidation.",
      "effect": "NASA Glenn says the hottest leading-edge panels are limited to 50 missions because oxidation of the carbon composite substrate lowers its strength. The limit comes from correlations of calculated mass loss with strength reduction. Leading-edge material with actual exposures up to 30 missions is now available to measure the strength loss.",
      "rating": "moderate",
      "conditions": {
        "basis": "limit set by empirical correlation; aging team tests as-fabricated, flown and furnace-oxidized material"
      },
      "source": "nasa-glenn-2005",
      "where": "Second and third paragraphs"
    },
    {
      "environment": "Re-entry exposure on an orbiter T-seal (nine missions), stagnation region",
      "headline": "Flown RCC has a higher outer-surface emittance at high temperature than virgin RCC.",
      "effect": "At 2040 to 2050 K the flown outer surface had a total normal emittance of 0.740 (Table 11), against 0.630 for virgin samples. The authors say the change may come from repeated flight exposure, and they did not confirm it with more flown samples.",
      "rating": "low",
      "conditions": {
        "samples": "two flown T-seal samples (outer surface) and two virgin samples",
        "temperature": "1200 to 2050 K"
      },
      "source": "nasa-tp3293",
      "where": "High Temperature Total Normal and Total Hemispherical Emittance; Conclusions"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "Tetraethoxysilane (TEOS), the impregnant precursor in RCC: PubChem ECHA notifications with signal word Warning give H226 Flammable liquid and vapor, H319 Causes serious eye irritation, H332 Harmful if inhaled and H335 May cause respiratory irritation. Notifications with signal word Danger add H370 Causes damage to organs and H372 Causes damage to organs through prolonged or repeated exposure. PubChem notes that 1 of 1197 reports say the chemical does not meet GHS hazard criteria. These statements describe the chemical as supplied, not cured RCC.",
        "ghs": [
          "H226",
          "H319",
          "H332",
          "H335",
          "H370",
          "H372"
        ],
        "source": "pubchem-teos",
        "where": "Safety and Hazards, GHS Classification and ECHA C&L Notifications Summary (CID 6517)"
      },
      {
        "text": "Silicon carbide (the outer coating material): PubChem ECHA notifications with signal word Danger give H350i May cause cancer by inhalation, and some add H372 Causes damage to organs through prolonged or repeated exposure. PubChem notes that 740 of 1053 reports say the chemical does not meet GHS hazard criteria, so classification varies by notifier. These statements describe the chemical as supplied, not an installed coating.",
        "ghs": [
          "H350i",
          "H372"
        ],
        "source": "pubchem-sic",
        "where": "Safety and Hazards, GHS Classification and ECHA C&L Notifications Summary (CID 9863)"
      },
      {
        "text": "Sodium silicate, PubChem record CID 23266 (the record covers sodium silicate in general and may not match the sodium silicate and SiC sealant mix in RCC): ECHA notifications with signal word Danger give H314 Causes severe skin burns and eye damage and H335 May cause respiratory irritation. Other notifications add H290 May be corrosive to metals, H302 Harmful if swallowed, H318 Causes serious eye damage and H371 May cause damage to organs. PubChem notes that 290 of 4043 reports say it does not meet GHS hazard criteria.",
        "ghs": [
          "H290",
          "H302",
          "H314",
          "H318",
          "H335",
          "H371"
        ],
        "source": "pubchem-sodium-silicate",
        "where": "Safety and Hazards, GHS Classification and ECHA C&L Notifications Summary (CID 23266)"
      }
    ],
    "failure_risks": [
      {
        "mode": "Oxidation of the carbon substrate through the SiC coating",
        "trigger": "Oxygen reaches the substrate through cracks or breaches in the SiC coating and TEOS-sealed surface, at high temperature in air",
        "consequence": "Substrate mass loss lowers the strength of the carbon composite, which limits mission life because the RCC can no longer carry the flight loads (NASA TM-104792)",
        "severity": "moderate",
        "source": "nasa-tm104792",
        "where": "Introduction, paragraphs 2 and 3"
      },
      {
        "mode": "SiC coating recession and breach at high surface temperature",
        "trigger": "Surface temperature above about 1967 K (3080 °F), for example in extended flight envelopes or abort entries",
        "consequence": "The SiC coating recedes, and above about 2061 K (3250 °F) SiO gas forms and breaches the coating, exposing the carbon substrate to active oxidation (arc-jet tests)",
        "severity": "moderate",
        "source": "nasa-tm104792",
        "where": "Over-Temperature Test Results"
      },
      {
        "mode": "Damaged RCC on the wing leading edge",
        "trigger": "Damage to the RCC wing leading-edge panel; NASA Glenn does not describe the impact or its cause in the feature we read",
        "consequence": "NASA Glenn states that the Columbia accident was caused by damaged RCC on the wing leading edge, which could not protect the wing components",
        "severity": "critical",
        "source": "nasa-glenn-2005",
        "where": "Fourth paragraph (Columbia accident statement)"
      }
    ],
    "side_effects": [
      {
        "text": "Flown RCC outer surface emits more at high temperature than virgin RCC (0.740 against 0.630 near 2040 to 2050 K). The authors call the higher emittance beneficial, because it reduces the heat absorbed into the material.",
        "affects": "Heat balance and surface temperature of the wing leading edge during entry",
        "source": "nasa-tp3293",
        "where": "High Temperature Total Normal and Total Hemispherical Emittance; Table 11"
      }
    ],
    "handling": [
      {
        "text": "After a single-engine-out abort the surface sealant is ablated and the RCC needs refurbishing before the next flight, although little surface recession occurred.",
        "source": "nasa-tm104792",
        "where": "Flight Predictions"
      },
      {
        "text": "NASA's return-to-flight aging team examines RCC as-fabricated, flown and furnace-oxidized, using nondestructive evaluation, microstructural examination and mechanical testing.",
        "source": "nasa-glenn-2005",
        "where": "Paragraphs 2 and 3"
      }
    ],
    "mitigations": [
      {
        "text": "A second application of sodium silicate sealant (double Type A) was made to RCC on the orbiter Endeavour to decrease subsurface oxidation and increase mission life.",
        "source": "nasa-tm104792",
        "where": "Introduction, paragraph 5, and Double Type A Tests"
      },
      {
        "text": "Limit the hottest leading-edge panels to 50 missions.",
        "source": "nasa-glenn-2005",
        "where": "Second paragraph"
      }
    ]
  },
  "uses": [
    {
      "application": "heat-shields",
      "device": "Orbiter wing leading edges and nose cap",
      "example": "NASA Glenn states that RCC is used on the wing leading edge and the nose cap, where maximum temperatures are reached on re-entry, and that the leading-edge system is a single-plate RCC construction about 1/4 in thick.",
      "source": "nasa-glenn-2005",
      "where": "Opening paragraph"
    },
    {
      "application": "heat-shields",
      "device": "High-temperature regions of the orbiter, where reusable surface insulation could not safely be used",
      "example": "NASA TM-104792 says RCC was selected for high-temperature regions where reusable surface insulation could not safely be used, and has been reused in those regions since the first flight of Columbia in April 1981.",
      "source": "nasa-tm104792",
      "where": "Introduction, paragraph 1"
    },
    {
      "application": "structures",
      "device": "Load-carrying wing leading-edge structure",
      "example": "NASA TM-104792 states that strength loss from substrate oxidation restricts mission life because the RCC will be unable to sustain the imposed flight loads.",
      "source": "nasa-tm104792",
      "where": "Introduction, paragraph 2"
    },
    {
      "application": "thermal-control",
      "device": "Radiative surface of the leading edge",
      "example": "NASA TP-3293 states that the SiC coating has a high total hemispherical emittance at normal operating temperatures around 1800 K, which enhances radiative heat rejection from the surface.",
      "source": "nasa-tp3293",
      "where": "Introduction"
    }
  ],
  "supply": [
    {
      "subject": "Natural graphite (related carbon feedstock; RCC is not made from natural graphite flake, and the sources read name fibre precursors only indirectly)",
      "producers": [
        {
          "country": "China",
          "share_percent": 82,
          "year": 2025
        }
      ],
      "critical_lists": [],
      "recycling": "USGS says the abundance of graphite in the world market inhibits increased recycling efforts, and the quantity of recycled graphite is not reported.",
      "substitutes": [
        "USGS lists synthetic graphite powder and calcined petroleum coke as competitors in steelmaking and battery uses; the summary does not discuss RCC."
      ],
      "source": "usgs-mcs2026-graphite",
      "where": "Text on world production (China 'an estimated 82% of total world production'); World Mine Production and Reserves table (2025e world total 1,800,000 t; China 1,400,000 t, about 78% of that total by calculation); Recycling; Substitutes"
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "Analysis of the Shuttle Orbiter Reinforced Carbon-Carbon Oxidation Protection System, NASA TM-104792 (1994)",
      "type": "report",
      "url": "https://ntrs.nasa.gov/api/citations/19940030739/downloads/19940030739.pdf",
      "year": 1994
    },
    {
      "title": "Emittance Measurements of Space Shuttle Orbiter Reinforced Carbon-Carbon, NASA Technical Paper 3293 (1992)",
      "type": "report",
      "url": "https://ntrs.nasa.gov/api/citations/19930006341/downloads/19930006341.pdf",
      "year": 1992
    },
    {
      "title": "As-Fabricated Reinforced Carbon/Carbon Characterized, NASA Glenn (2005)",
      "type": "report",
      "url": "https://ntrs.nasa.gov/api/citations/20050217101/downloads/20050217101.pdf",
      "year": 2005
    },
    {
      "title": "Wikipedia: Reinforced carbon-carbon (composition and use only)",
      "type": "database",
      "url": "https://en.wikipedia.org/wiki/Reinforced_carbon-carbon"
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026: Graphite (Natural)",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-graphite.pdf",
      "year": 2026
    }
  ],
  "gaps": [
    "No flexural, tensile, compressive or fracture strength of RCC was found in the three NASA sources read; the strength values for this profile are missing, and the 1994 report only names strength loss from oxidation.",
    "No coefficient of thermal expansion for RCC was found; NASA TP-3293 says RCC has a low coefficient but prints no number.",
    "The brief's figure of about 1650 C is not printed in any page read. The pages print 1811 K (2800 °F) as the multi-mission design maximum and 2088 K (3300 °F) as predicted abort surface temperatures; Wikipedia says the material keeps its properties above 2000 °C without a service limit.",
    "No atomic-oxygen erosion yield, NASA outgassing (total mass loss) or radiation test result for RCC was found.",
    "No SDS or PubChem GHS record for the finished RCC part was found. The hazard entries cover its constituents (TEOS, silicon carbide and the PubChem sodium silicate record), and the sodium silicate record may not match the Na2SiO3 sealant mix exactly.",
    "Atomic weights of carbon, silicon, sodium and oxygen were not read in a fetched page, so the recipe parts carry no atomic weight.",
    "No producer shares were found for carbon fibre precursors (PAN or rayon) or for RCC manufacturers. NASA TM-104792 names AVTEX and ENKA RCC substrates, and NASA TP-3293 names LTV Corporation, but no production data are given. The graphite row is a related carbon feedstock only.",
    "Graphite critical-mineral status (USGS 2025 list and EU list) was not read in this run, so critical_lists is empty.",
    "The SiC coating conductivity in NASA TM-104792 Table B 1 (64.07441 cal/(cm·s·K)) is marked as undocumented calculations and is not recorded.",
    "The carbon substrate density, specific heat and conductivities come from Appendix B, which cites personal communications; they are not measured values from a test in the report.",
    "No designations (UNS, EN, ASTM, AMS or trade names) for RCC were printed in the sources read.",
    "The NASA emittance table gives 0.890 at 1205 K and 0.630 at 2040 K, while the text gives 0.89 at 1200 K and 0.63 at 2050 K; both are recorded and the difference is noted.",
    "Recession and emittance data come from one flight sample set (two T-seal samples from one orbiter) and a limited set of high-temperature points, as the authors state."
  ],
  "story": {
    "why": "Reinforced carbon-carbon (RCC) is the high-temperature leading-edge material of the Space Shuttle orbiter. NASA states that RCC was selected for the hottest orbiter regions where reusable surface insulation could not safely be used, and that it has flown on the orbiters since the first flight of Columbia in April 1981. The carbon composite is strong at high temperature but oxidises in air, so each RCC panel carries a three-layer oxidation barrier: a SiC coating, TEOS impregnation and a sodium silicate sealant. The design maximum for nominal multi-mission flights is 1811 K (2800 °F).",
    "uses": [
      {
        "where": "Orbiter wing leading edges and nose cap",
        "line": "NASA Glenn states that RCC is used on the wing leading edge and the nose cap, where maximum temperatures are reached on re-entry. The leading-edge wall is a single-plate RCC construction about 1/4 in thick."
      },
      {
        "where": "High-temperature orbiter regions",
        "line": "NASA TM-104792 says RCC was selected for high-temperature regions where reusable surface insulation could not safely be used, and has been reused there since the first flight of Columbia in April 1981."
      },
      {
        "where": "Wing leading-edge structure",
        "line": "NASA TM-104792 notes that RCC must carry the imposed flight loads, so strength lost to substrate oxidation is what limits the mission life."
      }
    ],
    "can_do": [
      {
        "label": "Heat tolerance",
        "line": "NASA TM-104792 gives 1811 K (2800 °F) as the original multi-mission maximum temperature for RCC. In arc-jet tests the SiC coating showed negligible recession below 1967 K (3080 °F).",
        "benchmark": "max_service_temp",
        "scope": "material",
        "value": "1811 K (2800 °F) design maximum"
      },
      {
        "label": "Radiating heat",
        "line": "Virgin RCC with its SiC coating has a total normal emittance of 0.847 and 0.858 at room temperature (NASA TP-3293). The emittance falls to 0.890 at 1205 K and 0.630 at 2040 K for virgin samples (Table 11).",
        "benchmark": "total_normal_emittance",
        "scope": "material",
        "value": "0.847 to 0.858 at room temperature"
      },
      {
        "label": "Conducting heat",
        "line": "The carbon substrate conducts 0.12815 cal/(cm·s·K) in the normal direction and 0.19991 cal/(cm·s·K) in the parallel direction at 311 K (NASA TM-104792, Table B 1; the table cites personal communications).",
        "benchmark": "thermal_conductivity",
        "scope": "material",
        "value": "0.12815 cal/(cm·s·K) normal at 311 K"
      },
      {
        "label": "Flight record",
        "line": "NASA Glenn says leading-edge RCC with exposures up to 30 missions is now available for strength testing, and sets a 50-mission limit on the hottest panels.",
        "benchmark": "flight_exposure",
        "scope": "material",
        "value": "Up to 30 missions of leading-edge exposure"
      }
    ],
    "compare": "The three RCC layers differ in density. The SiC coating is 2.114 g/cm3, the Type A sealant 1.73 g/cm3 and the carbon substrate 1.362 g/cm3 (NASA TM-104792, Table B 1). In radiative terms, the flown outer surface keeps a higher emittance at high temperature than the virgin surface: 0.740 at 2050 K against 0.630 near 2040 K (NASA TP-3293, Table 11). The sources give no strength or expansion values for RCC, so this profile can compare its layers and surfaces with each other but not its strength with other materials.",
    "compare_rows": [
      {
        "label": "Density of the carbon substrate",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Thermal conductivity of the carbon substrate",
        "benchmark": "thermal_conductivity",
        "scope": "material"
      },
      {
        "label": "Specific heat of the carbon substrate",
        "benchmark": "specific_heat",
        "scope": "material"
      }
    ],
    "handling": [
      "Expect the material to oxidise in air above about 1967 K (3080 °F), where the SiC coating starts to recede in arc-jet tests.",
      "Refurbish the sealant and coating after an abort entry before the next flight.",
      "Keep count of flights: the hottest leading-edge panels are limited to 50 missions."
    ],
    "good_for": [
      "Leading edges and nose caps that see re-entry heat up to 1811 K (2800 °F) (NASA design maximum).",
      "Radiating heat from a hot surface: virgin SiC-coated RCC has a total normal emittance of 0.847 to 0.858 at room temperature."
    ],
    "watch_out": [
      "Oxidation of the carbon substrate limits mission life once the coating is breached.",
      "Strength values are missing from this profile; no flexural or tensile value for RCC was found in the sources read.",
      "The Columbia accident was caused by damaged RCC on the wing leading edge (NASA Glenn, 2005)."
    ],
    "verdict": "RCC is the proven high-temperature leading-edge material of the Space Shuttle orbiter. Its SiC, TEOS and sealant layers resist oxidation up to about 1967 K (3080 °F), and flight use is limited to 50 missions on the hottest panels. This profile has no strength or expansion values, and its hazard entries cover its constituents, not the finished part.",
    "recipe": {
      "line": "Reinforced carbon-carbon is a carbon-fibre reinforced composite with a carbon matrix, laid up as a two-dimensional carbon structure (NASA Glenn, 2005; Wikipedia). The outer carbon is converted to silicon carbide by diffusion coating, the composite is impregnated with TEOS which cures to silicon dioxide, and a sodium silicate and SiC sealant (Type A) fills surface pores and microcracks (NASA TM-104792).",
      "parts": [
        {
          "name": "Carbon fibre",
          "symbol": "C",
          "role": "Reinforcement. Carbon fibres in a two-dimensional layup carry the load and give the composite its strength and stiffness."
        },
        {
          "name": "Carbon matrix",
          "symbol": "C",
          "role": "Graphite matrix formed by pyrolysis of the resin. NASA Glenn says pores form when resin shrinks during pyrolysis."
        },
        {
          "name": "Silicon carbide coating",
          "symbol": "SiC",
          "role": "Outer coating converted from the carbon surface. It has a density of 2.114 g/cm3 and is the first oxidation barrier."
        },
        {
          "name": "Tetraethyl orthosilicate (TEOS)",
          "symbol": "Si(OC2H5)4",
          "role": "Impregnant that cures to silicon dioxide (SiO2) throughout the coating and carbon substrate, adding a second oxidation barrier."
        },
        {
          "name": "Sodium silicate sealant",
          "symbol": "Na2SiO3",
          "role": "Type A surface sealant mixed with SiC particles. It fills porosity and microcracks at the surface and melts and flows at high temperature."
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "No safety data sheet or GHS record for the finished RCC part was found. PubChem GHS records exist for its three constituents: TEOS, silicon carbide and sodium silicate.",
        "points": [
          {
            "label": "The material",
            "line": "PubChem classifies the constituents as supplied, not the installed RCC. Check the manufacturer's data sheet before handling machined or broken RCC."
          },
          {
            "label": "Dust from machining",
            "line": "The sources do not discuss dust from RCC machining or repair. PubChem gives silicon carbide H350i (May cause cancer by inhalation), so limit breathing its dust until a data sheet says otherwise."
          }
        ],
        "level": 1,
        "verdict": "Constituent hazard data only; none for finished RCC"
      },
      {
        "title": "If it fails",
        "lead": "The failure routes below come from NASA's arc-jet tests, flight predictions and the Columbia accident. They are not from field incidents of the same kind.",
        "points": [
          {
            "label": "Oxidation",
            "line": "Oxygen that gets through the coating oxidises the carbon substrate, which lowers its strength and limits how many missions the panel can fly (NASA TM-104792)."
          },
          {
            "label": "Very high temperature",
            "line": "Above 1967 K (3080 °F) the SiC coating recedes in arc-jet tests. Near 2061 K (3250 °F) SiO gas forms, the coating breaches, and bare carbon oxidises actively."
          },
          {
            "label": "Columbia",
            "line": "NASA Glenn states that the Columbia accident was caused by damaged RCC on the wing leading edge, which could no longer protect the wing components."
          }
        ]
      },
      {
        "title": "Handling and inspection",
        "points": [
          {
            "label": "Refurbishing",
            "line": "After a single-engine-out abort, RCC refurbishing is required before the next flight (NASA TM-104792)."
          },
          {
            "label": "Limits",
            "line": "The hottest leading-edge panels are limited to 50 missions (NASA Glenn, 2005)."
          }
        ]
      }
    ]
  },
  "updated": "2026-11-02",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 20,
    "unreachable": 0,
    "caveats": 6,
    "note": "Values read by an AI assistant on 2026-11-01 from the three NASA PDFs (text extracted with pdftotext), the Wikipedia page and the USGS graphite summary. Caveats: no strength or thermal-expansion values for RCC were found; the carbon substrate values come from a table citing personal communications; the emittance table and text give slightly different temperatures for two values; the 1650 C figure in the brief is not printed in the sources; eight sources. Hazards added 2026-11-02 from PubChem GHS records for TEOS, silicon carbide and sodium silicate (constituents, not the finished part)."
  },
  "sources": {
    "nasa-tm104792": {
      "title": "Analysis of the Shuttle Orbiter Reinforced Carbon-Carbon Oxidation Protection System (NASA TM-104792; S. D. Williams, D. M. Curry, D. Chao, V. T. Pham)",
      "id": "NASA TM-104792; NTRS 19940030739; N94-35245",
      "url": "https://ntrs.nasa.gov/api/citations/19940030739/downloads/19940030739.pdf",
      "year": 1994,
      "kind": "report",
      "license": "public domain (NASA)"
    },
    "nasa-tp3293": {
      "title": "Emittance Measurements of Space Shuttle Orbiter Reinforced Carbon-Carbon (NASA Technical Paper 3293; J. M. Caram, S. A. Bouslog, G. R. Cunnington Jr.)",
      "id": "NASA TP-3293; NTRS 19930006341",
      "url": "https://ntrs.nasa.gov/api/citations/19930006341/downloads/19930006341.pdf",
      "year": 1992,
      "kind": "report",
      "license": "public domain (NASA)"
    },
    "nasa-glenn-2005": {
      "title": "As-Fabricated Reinforced Carbon/Carbon Characterized (NASA Glenn; N. S. Jacobson, A. M. Calomino, N. Webster)",
      "id": "NTRS 20050217101",
      "url": "https://ntrs.nasa.gov/api/citations/20050217101/downloads/20050217101.pdf",
      "year": 2005,
      "kind": "report",
      "license": "public domain (NASA)"
    },
    "wikipedia-rcc": {
      "title": "Reinforced carbon-carbon (Wikipedia)",
      "url": "https://en.wikipedia.org/wiki/Reinforced_carbon-carbon",
      "kind": "web",
      "license": "CC BY-SA 4.0 (cited, not reproduced)"
    },
    "usgs-mcs2026-graphite": {
      "title": "Mineral Commodity Summaries 2026, Graphite (Natural)",
      "id": "USGS MCS 2026, February 2026",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-graphite.pdf",
      "year": 2026,
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "pubchem-teos": {
      "title": "PubChem compound record, Tetraethoxysilane (tetraethyl orthosilicate, TEOS), GHS Classification",
      "id": "CID 6517",
      "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/6517/JSON?heading=GHS+Classification",
      "year": 2026,
      "kind": "database",
      "license": "public domain (NCBI)"
    },
    "pubchem-sic": {
      "title": "PubChem compound record, Silicon carbide, GHS Classification",
      "id": "CID 9863",
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