{
  "spore": "profile",
  "id": "boron-nitride",
  "spore_version": "0.2",
  "family": "carbide-nitride-boride-ceramics",
  "name": "Hexagonal boron nitride",
  "abbreviation": "h-BN",
  "role": "electrical insulator and thermal ceramic",
  "category": "ceramics",
  "type": "nitrides",
  "summary": "Hexagonal boron nitride (h-BN) is a graphite-like layered form of BN. Hot-pressed ceramic grades are electrically insulating and resist thermal shock. Precision Ceramics Grade A has a bending strength of 94 MPa parallel to the pressing direction and 65 MPa perpendicular to it, a dielectric strength of 88 kV/mm, and is rated to 850 °C in air. Its thermal conductivity is only 30 to 34 W/(m·K), far below the 600 W/(m·K) quoted for the basal planes of the h-BN material, and NASA measured bending strength falling from 39.7 MPa to 9.8 MPa at 600 °C in one hot-pressed grade.\n",
  "best_for": "Electrical insulation and microwave or high-temperature insulating parts, where the 88 kV/mm dielectric strength and the 850 °C air limit of Grade A matter",
  "weakest_at": "Strength across or at high temperature: HP bending strength parallel to pressing falls from 39.7 MPa at 25 °C to 9.8 MPa at 600 °C, and oxidation in ambient air begins near 900 °C",
  "identity": {
    "formula": "BN, hexagonal boron nitride (one boron and one nitrogen atom per formula unit, bonded in graphite-like layers). Hot-pressed grades contain a binder: calcium borate in NASA's HP grade, B2O3 in the SAM BN-BO Grade A",
    "cas": "10043-11-5",
    "designations": [
      {
        "system": "Trade name",
        "code": "Grade A",
        "note": "Precision Ceramics name for its hot-pressed h-BN grade, Mean and typical values",
        "source": "pc-uk-grade-a",
        "where": "Title line of the material datasheet"
      },
      {
        "system": "Trade name",
        "code": "HP",
        "note": "Saint-Gobain hot-pressed h-BN grade with calcium borate binder",
        "source": "nasa-2020-bn",
        "where": "Materials of Interest table, Grade column"
      },
      {
        "system": "Trade name",
        "code": "AX05",
        "note": "h-BN above 99.5 %, self-bonded, as listed by Stanford Advanced Materials",
        "source": "sam-bn-hp",
        "where": "Hot Pressed Boron Nitride Crucible specification table, column BN99 (Grade AX05)"
      },
      {
        "system": "Trade name",
        "code": "PT110",
        "note": "Momentive powder used as the h-BN starting material for hot-pressed composites, not a dense ceramic",
        "source": "nasa-2017-hbn",
        "where": "Experimental section, paragraph on the h-BN material"
      }
    ],
    "source": "pubchem-bn",
    "where": "Molecular Formula BN and the CAS number 10043-11-5 in the Identifiers section, CID 66227"
  },
  "tags": {
    "environments": [],
    "stresses": [
      "extreme-heat"
    ],
    "applications": [
      "propulsion-and-tanks",
      "electronics-and-chips",
      "mechanisms"
    ]
  },
  "properties": [
    {
      "benchmark": "density",
      "label": "Density, hot-pressed boron nitride Grade A",
      "value": 2,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "grade": "Grade A (Precision Ceramics UK)",
        "form": "hot-pressed",
        "temperature": "not stated",
        "unit_in_source": "g/cm3"
      },
      "method": "Mean and typical value printed in a manufacturer material datasheet, with the datasheet disclaimer that values are indicative",
      "status": "ground",
      "source": "pc-uk-grade-a",
      "where": "Material datasheet, Mechanical block, row Density",
      "source_detail": {
        "title": "Precision Ceramics UK, Material Datasheet: Boron Nitride (BN) Grade A",
        "url": "https://precision-ceramics.com/wp-content/uploads/2018/07/Boron-Nitride-Grade-A-Technical-Data-Sheet-en.pdf",
        "year": 2018,
        "kind": "datasheet",
        "license": "Manufacturer datasheet, cited not reproduced"
      }
    },
    {
      "benchmark": "flexural_strength",
      "label": "Flexural strength at 25 °C, Grade A, parallel to pressing",
      "value": 94,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "Grade A (Precision Ceramics UK)",
        "temperature": "25 °C",
        "direction": "parallel to hot-press direction",
        "form": "hot-pressed"
      },
      "method": "Mean and typical value printed in a manufacturer material datasheet",
      "status": "ground",
      "source": "pc-uk-grade-a",
      "where": "Material datasheet, Mechanical block, row Flexural Strength at 25 °C, column 94 parallel",
      "source_detail": {
        "title": "Precision Ceramics UK, Material Datasheet: Boron Nitride (BN) Grade A",
        "url": "https://precision-ceramics.com/wp-content/uploads/2018/07/Boron-Nitride-Grade-A-Technical-Data-Sheet-en.pdf",
        "year": 2018,
        "kind": "datasheet",
        "license": "Manufacturer datasheet, cited not reproduced"
      }
    },
    {
      "benchmark": "flexural_strength",
      "label": "Flexural strength at 25 °C, Grade A, perpendicular to pressing",
      "value": 65,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "Grade A (Precision Ceramics UK)",
        "temperature": "25 °C",
        "direction": "perpendicular to hot-press direction",
        "form": "hot-pressed"
      },
      "method": "Mean and typical value printed in a manufacturer material datasheet",
      "status": "ground",
      "source": "pc-uk-grade-a",
      "where": "Material datasheet, Mechanical block, row Flexural Strength at 25 °C, column 65 perpendicular",
      "source_detail": {
        "title": "Precision Ceramics UK, Material Datasheet: Boron Nitride (BN) Grade A",
        "url": "https://precision-ceramics.com/wp-content/uploads/2018/07/Boron-Nitride-Grade-A-Technical-Data-Sheet-en.pdf",
        "year": 2018,
        "kind": "datasheet",
        "license": "Manufacturer datasheet, cited not reproduced"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Young's modulus, Grade A, parallel to pressing",
      "value": 47,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "grade": "Grade A (Precision Ceramics UK)",
        "direction": "parallel to hot-press direction",
        "temperature": "not stated"
      },
      "method": "Value printed in a manufacturer material datasheet",
      "status": "ground",
      "source": "pc-uk-grade-a",
      "where": "Material datasheet, Mechanical block, row Young's Modulus",
      "source_detail": {
        "title": "Precision Ceramics UK, Material Datasheet: Boron Nitride (BN) Grade A",
        "url": "https://precision-ceramics.com/wp-content/uploads/2018/07/Boron-Nitride-Grade-A-Technical-Data-Sheet-en.pdf",
        "year": 2018,
        "kind": "datasheet",
        "license": "Manufacturer datasheet, cited not reproduced"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Young's modulus, Grade A, perpendicular to pressing",
      "value": 74,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "grade": "Grade A (Precision Ceramics UK)",
        "direction": "perpendicular to hot-press direction",
        "temperature": "not stated"
      },
      "method": "Value printed in a manufacturer material datasheet",
      "status": "ground",
      "source": "pc-uk-grade-a",
      "where": "Material datasheet, Mechanical block, row Young's Modulus",
      "source_detail": {
        "title": "Precision Ceramics UK, Material Datasheet: Boron Nitride (BN) Grade A",
        "url": "https://precision-ceramics.com/wp-content/uploads/2018/07/Boron-Nitride-Grade-A-Technical-Data-Sheet-en.pdf",
        "year": 2018,
        "kind": "datasheet",
        "license": "Manufacturer datasheet, cited not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, Grade A, parallel to pressing",
      "value": 30,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "grade": "Grade A (Precision Ceramics UK)",
        "direction": "parallel to hot-press direction",
        "temperature": "not stated",
        "unit_in_source": "W/mK"
      },
      "method": "Value printed in a manufacturer material datasheet",
      "status": "ground",
      "source": "pc-uk-grade-a",
      "where": "Material datasheet, Thermal block, row Thermal Conductivity, column 30 parallel",
      "source_detail": {
        "title": "Precision Ceramics UK, Material Datasheet: Boron Nitride (BN) Grade A",
        "url": "https://precision-ceramics.com/wp-content/uploads/2018/07/Boron-Nitride-Grade-A-Technical-Data-Sheet-en.pdf",
        "year": 2018,
        "kind": "datasheet",
        "license": "Manufacturer datasheet, cited not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, Grade A, perpendicular to pressing",
      "value": 34,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "grade": "Grade A (Precision Ceramics UK)",
        "direction": "perpendicular to hot-press direction",
        "temperature": "not stated",
        "unit_in_source": "W/mK"
      },
      "method": "Value printed in a manufacturer material datasheet",
      "status": "ground",
      "source": "pc-uk-grade-a",
      "where": "Material datasheet, Thermal block, row Thermal Conductivity, column 34 perpendicular",
      "source_detail": {
        "title": "Precision Ceramics UK, Material Datasheet: Boron Nitride (BN) Grade A",
        "url": "https://precision-ceramics.com/wp-content/uploads/2018/07/Boron-Nitride-Grade-A-Technical-Data-Sheet-en.pdf",
        "year": 2018,
        "kind": "datasheet",
        "license": "Manufacturer datasheet, cited not reproduced"
      }
    },
    {
      "benchmark": "cte",
      "label": "Coefficient of thermal expansion 25 to 400 °C, Grade A, parallel to pressing",
      "value": 3,
      "bound": "exact",
      "unit": "ppm/K",
      "scope": "material",
      "conditions": {
        "grade": "Grade A (Precision Ceramics UK)",
        "temperature_range": "25 to 400 °C",
        "direction": "parallel to hot-press direction",
        "unit_in_source": "10^-6/K"
      },
      "method": "Value printed in a manufacturer material datasheet",
      "status": "ground",
      "source": "pc-uk-grade-a",
      "where": "Material datasheet, Thermal block, row CTE at 25 to 400 °C",
      "source_detail": {
        "title": "Precision Ceramics UK, Material Datasheet: Boron Nitride (BN) Grade A",
        "url": "https://precision-ceramics.com/wp-content/uploads/2018/07/Boron-Nitride-Grade-A-Technical-Data-Sheet-en.pdf",
        "year": 2018,
        "kind": "datasheet",
        "license": "Manufacturer datasheet, cited not reproduced"
      }
    },
    {
      "benchmark": "cte",
      "label": "Coefficient of thermal expansion 25 to 400 °C, Grade A, perpendicular to pressing",
      "value": 3,
      "bound": "exact",
      "unit": "ppm/K",
      "scope": "material",
      "conditions": {
        "grade": "Grade A (Precision Ceramics UK)",
        "temperature_range": "25 to 400 °C",
        "direction": "perpendicular to hot-press direction",
        "unit_in_source": "10^-6/K"
      },
      "method": "Value printed in a manufacturer material datasheet",
      "status": "ground",
      "source": "pc-uk-grade-a",
      "where": "Material datasheet, Thermal block, row CTE at 25 to 400 °C",
      "source_detail": {
        "title": "Precision Ceramics UK, Material Datasheet: Boron Nitride (BN) Grade A",
        "url": "https://precision-ceramics.com/wp-content/uploads/2018/07/Boron-Nitride-Grade-A-Technical-Data-Sheet-en.pdf",
        "year": 2018,
        "kind": "datasheet",
        "license": "Manufacturer datasheet, cited not reproduced"
      }
    },
    {
      "benchmark": "cte",
      "label": "Coefficient of thermal expansion 400 to 800 °C, Grade A, parallel to pressing",
      "value": 2,
      "bound": "exact",
      "unit": "ppm/K",
      "scope": "material",
      "conditions": {
        "grade": "Grade A (Precision Ceramics UK)",
        "temperature_range": "400 to 800 °C",
        "direction": "parallel to hot-press direction",
        "unit_in_source": "10^-6/K"
      },
      "method": "Value printed in a manufacturer material datasheet",
      "status": "ground",
      "source": "pc-uk-grade-a",
      "where": "Material datasheet, Thermal block, row CTE at 400 to 800 °C",
      "source_detail": {
        "title": "Precision Ceramics UK, Material Datasheet: Boron Nitride (BN) Grade A",
        "url": "https://precision-ceramics.com/wp-content/uploads/2018/07/Boron-Nitride-Grade-A-Technical-Data-Sheet-en.pdf",
        "year": 2018,
        "kind": "datasheet",
        "license": "Manufacturer datasheet, cited not reproduced"
      }
    },
    {
      "benchmark": "cte",
      "label": "Coefficient of thermal expansion 400 to 800 °C, Grade A, perpendicular to pressing",
      "value": 1.4,
      "bound": "exact",
      "unit": "ppm/K",
      "scope": "material",
      "conditions": {
        "grade": "Grade A (Precision Ceramics UK)",
        "temperature_range": "400 to 800 °C",
        "direction": "perpendicular to hot-press direction",
        "unit_in_source": "10^-6/K"
      },
      "method": "Value printed in a manufacturer material datasheet",
      "status": "ground",
      "source": "pc-uk-grade-a",
      "where": "Material datasheet, Thermal block, row CTE at 400 to 800 °C",
      "source_detail": {
        "title": "Precision Ceramics UK, Material Datasheet: Boron Nitride (BN) Grade A",
        "url": "https://precision-ceramics.com/wp-content/uploads/2018/07/Boron-Nitride-Grade-A-Technical-Data-Sheet-en.pdf",
        "year": 2018,
        "kind": "datasheet",
        "license": "Manufacturer datasheet, cited not reproduced"
      }
    },
    {
      "benchmark": "max_service_temp",
      "label": "Maximum temperature in air, Grade A",
      "value": 850,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "grade": "Grade A (Precision Ceramics UK)",
        "atmosphere": "air"
      },
      "method": "Maximum temperature printed in a manufacturer material datasheet; not a component design allowable",
      "status": "ground",
      "source": "pc-uk-grade-a",
      "where": "Material datasheet, Thermal block, row Maximum Temperature (Air)",
      "source_detail": {
        "title": "Precision Ceramics UK, Material Datasheet: Boron Nitride (BN) Grade A",
        "url": "https://precision-ceramics.com/wp-content/uploads/2018/07/Boron-Nitride-Grade-A-Technical-Data-Sheet-en.pdf",
        "year": 2018,
        "kind": "datasheet",
        "license": "Manufacturer datasheet, cited not reproduced"
      }
    },
    {
      "benchmark": "max_service_temp",
      "label": "Maximum temperature in inert atmosphere, Grade A",
      "value": 1200,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "grade": "Grade A (Precision Ceramics UK)",
        "atmosphere": "inert"
      },
      "method": "Maximum temperature printed in a manufacturer material datasheet; not a component design allowable",
      "status": "ground",
      "source": "pc-uk-grade-a",
      "where": "Material datasheet, Thermal block, row Maximum Temperature (Inert)",
      "source_detail": {
        "title": "Precision Ceramics UK, Material Datasheet: Boron Nitride (BN) Grade A",
        "url": "https://precision-ceramics.com/wp-content/uploads/2018/07/Boron-Nitride-Grade-A-Technical-Data-Sheet-en.pdf",
        "year": 2018,
        "kind": "datasheet",
        "license": "Manufacturer datasheet, cited not reproduced"
      }
    },
    {
      "benchmark": "dielectric_constant",
      "label": "Dielectric constant at 1 MHz, Grade A, parallel to pressing",
      "value": 4.6,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "grade": "Grade A (Precision Ceramics UK)",
        "frequency": "1 MHz",
        "direction": "parallel to hot-press direction"
      },
      "method": "Value printed in a manufacturer material datasheet",
      "status": "ground",
      "source": "pc-uk-grade-a",
      "where": "Material datasheet, Electrical block, row Dielectric Constant at 1 MHz, column 4.6 parallel",
      "source_detail": {
        "title": "Precision Ceramics UK, Material Datasheet: Boron Nitride (BN) Grade A",
        "url": "https://precision-ceramics.com/wp-content/uploads/2018/07/Boron-Nitride-Grade-A-Technical-Data-Sheet-en.pdf",
        "year": 2018,
        "kind": "datasheet",
        "license": "Manufacturer datasheet, cited not reproduced"
      }
    },
    {
      "benchmark": "dielectric_constant",
      "label": "Dielectric constant at 1 MHz, Grade A, perpendicular to pressing",
      "value": 4.2,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "grade": "Grade A (Precision Ceramics UK)",
        "frequency": "1 MHz",
        "direction": "perpendicular to hot-press direction"
      },
      "method": "Value printed in a manufacturer material datasheet",
      "status": "ground",
      "source": "pc-uk-grade-a",
      "where": "Material datasheet, Electrical block, row Dielectric Constant at 1 MHz, column 4.2 perpendicular",
      "source_detail": {
        "title": "Precision Ceramics UK, Material Datasheet: Boron Nitride (BN) Grade A",
        "url": "https://precision-ceramics.com/wp-content/uploads/2018/07/Boron-Nitride-Grade-A-Technical-Data-Sheet-en.pdf",
        "year": 2018,
        "kind": "datasheet",
        "license": "Manufacturer datasheet, cited not reproduced"
      }
    },
    {
      "benchmark": "dielectric_strength",
      "label": "Dielectric strength DC, Grade A",
      "value": 88,
      "bound": "exact",
      "unit": "kV/mm",
      "scope": "material",
      "conditions": {
        "grade": "Grade A (Precision Ceramics UK)",
        "direction": "not stated",
        "current": "DC"
      },
      "method": "Value printed in a manufacturer material datasheet",
      "status": "ground",
      "source": "pc-uk-grade-a",
      "where": "Material datasheet, Electrical block, row Dielectric Strength DC",
      "source_detail": {
        "title": "Precision Ceramics UK, Material Datasheet: Boron Nitride (BN) Grade A",
        "url": "https://precision-ceramics.com/wp-content/uploads/2018/07/Boron-Nitride-Grade-A-Technical-Data-Sheet-en.pdf",
        "year": 2018,
        "kind": "datasheet",
        "license": "Manufacturer datasheet, cited not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity parallel to pressing, hot-pressed HP grade, lot 1",
      "value": 33,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "grade": "HP (Saint-Gobain BN with calcium borate binder)",
        "direction": "parallel to hot-press direction",
        "method_in_source": "ASTM E1461",
        "temperature": "not stated in the table",
        "unit_in_source": "W/m-K"
      },
      "method": "Measured at NASA Glenn Research Center on a sample set of the HP grade and printed in a table",
      "status": "ground",
      "source": "nasa-2020-bn",
      "where": "General Properties Overview (cont.), table Property trends in BN/SiO2 content, row Thermal Conductivity, column HP parallel",
      "source_detail": {
        "title": "Lot-to-lot Variability of BN Grades for Space Electric Propulsion Applications (Mackey, Salem, Stanford, Kamhawi, McEnerney, Hofer)",
        "id": "NTRS 20200000860, 2020",
        "url": "https://ntrs.nasa.gov/citations/20200000860",
        "year": 2020,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity perpendicular to pressing, hot-pressed HP grade, lot 1",
      "value": 31,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "grade": "HP (Saint-Gobain BN with calcium borate binder)",
        "direction": "perpendicular to hot-press direction",
        "method_in_source": "ASTM E1461",
        "temperature": "not stated in the table",
        "unit_in_source": "W/m-K"
      },
      "method": "Measured at NASA Glenn Research Center and printed in a table",
      "status": "ground",
      "source": "nasa-2020-bn",
      "where": "General Properties Overview (cont.), table Property trends in BN/SiO2 content, row Thermal Conductivity, column HP perpendicular",
      "source_detail": {
        "title": "Lot-to-lot Variability of BN Grades for Space Electric Propulsion Applications (Mackey, Salem, Stanford, Kamhawi, McEnerney, Hofer)",
        "id": "NTRS 20200000860, 2020",
        "url": "https://ntrs.nasa.gov/citations/20200000860",
        "year": 2020,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "cte",
      "label": "Coefficient of thermal expansion, hot-pressed HP grade, parallel to pressing",
      "value": 3.1,
      "bound": "exact",
      "unit": "ppm/K",
      "scope": "material",
      "conditions": {
        "grade": "HP (Saint-Gobain BN with calcium borate binder)",
        "direction": "parallel to hot-press direction",
        "method_in_source": "dilatometry",
        "temperature": "not stated in the table",
        "unit_in_source": "μm/m-K"
      },
      "method": "Measured by dilatometry at NASA Glenn Research Center and printed in a table",
      "status": "ground",
      "source": "nasa-2020-bn",
      "where": "General Properties Overview (cont.), table Property trends in BN/SiO2 content, row CTE, column HP parallel",
      "source_detail": {
        "title": "Lot-to-lot Variability of BN Grades for Space Electric Propulsion Applications (Mackey, Salem, Stanford, Kamhawi, McEnerney, Hofer)",
        "id": "NTRS 20200000860, 2020",
        "url": "https://ntrs.nasa.gov/citations/20200000860",
        "year": 2020,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "cte",
      "label": "Coefficient of thermal expansion, hot-pressed HP grade, perpendicular to pressing",
      "value": 0.4,
      "bound": "exact",
      "unit": "ppm/K",
      "scope": "material",
      "conditions": {
        "grade": "HP (Saint-Gobain BN with calcium borate binder)",
        "direction": "perpendicular to hot-press direction",
        "method_in_source": "dilatometry",
        "temperature": "not stated in the table",
        "unit_in_source": "μm/m-K"
      },
      "method": "Measured by dilatometry at NASA Glenn Research Center and printed in a table",
      "status": "ground",
      "source": "nasa-2020-bn",
      "where": "General Properties Overview (cont.), table Property trends in BN/SiO2 content, row CTE, column HP perpendicular",
      "source_detail": {
        "title": "Lot-to-lot Variability of BN Grades for Space Electric Propulsion Applications (Mackey, Salem, Stanford, Kamhawi, McEnerney, Hofer)",
        "id": "NTRS 20200000860, 2020",
        "url": "https://ntrs.nasa.gov/citations/20200000860",
        "year": 2020,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Elastic modulus, hot-pressed HP grade, parallel to pressing",
      "value": 80,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "grade": "HP (Saint-Gobain BN with calcium borate binder)",
        "direction": "parallel to hot-press direction",
        "method_in_source": "ASTM C1259",
        "temperature": "not stated in the table"
      },
      "method": "Measured at NASA Glenn Research Center and printed in a table",
      "status": "ground",
      "source": "nasa-2020-bn",
      "where": "General Properties Overview (cont.), table Property trends in BN/SiO2 content, row Elastic Modulus, column HP parallel",
      "source_detail": {
        "title": "Lot-to-lot Variability of BN Grades for Space Electric Propulsion Applications (Mackey, Salem, Stanford, Kamhawi, McEnerney, Hofer)",
        "id": "NTRS 20200000860, 2020",
        "url": "https://ntrs.nasa.gov/citations/20200000860",
        "year": 2020,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Elastic modulus, hot-pressed HP grade, perpendicular to pressing",
      "value": 79,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "grade": "HP (Saint-Gobain BN with calcium borate binder)",
        "direction": "perpendicular to hot-press direction",
        "method_in_source": "ASTM C1259",
        "temperature": "not stated in the table"
      },
      "method": "Measured at NASA Glenn Research Center and printed in a table",
      "status": "ground",
      "source": "nasa-2020-bn",
      "where": "General Properties Overview (cont.), table Property trends in BN/SiO2 content, row Elastic Modulus, column HP perpendicular",
      "source_detail": {
        "title": "Lot-to-lot Variability of BN Grades for Space Electric Propulsion Applications (Mackey, Salem, Stanford, Kamhawi, McEnerney, Hofer)",
        "id": "NTRS 20200000860, 2020",
        "url": "https://ntrs.nasa.gov/citations/20200000860",
        "year": 2020,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "dielectric_constant",
      "label": "Dielectric constant, hot-pressed HP grade, parallel to pressing",
      "value": 4.7,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "grade": "HP (Saint-Gobain BN with calcium borate binder)",
        "direction": "parallel to hot-press direction",
        "method_in_source": "impedance spectroscopy",
        "temperature": "not stated in the table"
      },
      "method": "Measured at NASA Glenn Research Center and printed in a table",
      "status": "ground",
      "source": "nasa-2020-bn",
      "where": "General Properties Overview (cont.), table Property trends in BN/SiO2 content, row Dielectric Constant, column HP parallel",
      "source_detail": {
        "title": "Lot-to-lot Variability of BN Grades for Space Electric Propulsion Applications (Mackey, Salem, Stanford, Kamhawi, McEnerney, Hofer)",
        "id": "NTRS 20200000860, 2020",
        "url": "https://ntrs.nasa.gov/citations/20200000860",
        "year": 2020,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "flexural_strength",
      "label": "Flexural strength at 25 °C, hot-pressed HP grade, parallel to pressing",
      "value": 39.7,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "HP (Saint-Gobain BN with calcium borate binder)",
        "temperature": "25 °C",
        "direction": "parallel to hot-press direction",
        "test": "4-point bend",
        "measure": "average of 26 or more samples",
        "sample_state": "the slide lists as-machined and dry or humidity-chamber samples but the table does not separate them",
        "lot": "not printed on this slide; the first lot characterised"
      },
      "method": "Average printed in a 4-point bend table at NASA Glenn Research Center",
      "status": "ground",
      "source": "nasa-2020-bn",
      "where": "Flexural Testing (cont.) table, row HP parallel, column Average at room temperature",
      "source_detail": {
        "title": "Lot-to-lot Variability of BN Grades for Space Electric Propulsion Applications (Mackey, Salem, Stanford, Kamhawi, McEnerney, Hofer)",
        "id": "NTRS 20200000860, 2020",
        "url": "https://ntrs.nasa.gov/citations/20200000860",
        "year": 2020,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "flexural_strength",
      "label": "Flexural strength at 25 °C, hot-pressed HP grade, perpendicular to pressing",
      "value": 70.5,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "HP (Saint-Gobain BN with calcium borate binder)",
        "temperature": "25 °C",
        "direction": "perpendicular to hot-press direction",
        "test": "4-point bend",
        "sample_state": "the table does not separate as-machined, dry or humidity-chamber samples",
        "lot": "not printed on this slide; the first lot characterised"
      },
      "method": "Average printed in a 4-point bend table at NASA Glenn Research Center",
      "status": "ground",
      "source": "nasa-2020-bn",
      "where": "Flexural Testing (cont.) table, row HP perpendicular, column Average at room temperature",
      "source_detail": {
        "title": "Lot-to-lot Variability of BN Grades for Space Electric Propulsion Applications (Mackey, Salem, Stanford, Kamhawi, McEnerney, Hofer)",
        "id": "NTRS 20200000860, 2020",
        "url": "https://ntrs.nasa.gov/citations/20200000860",
        "year": 2020,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "flexural_strength",
      "label": "Flexural strength at 600 °C, hot-pressed HP grade, parallel to pressing",
      "value": 9.8,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "HP (Saint-Gobain BN with calcium borate binder)",
        "temperature": "600 °C",
        "direction": "parallel to hot-press direction",
        "test": "4-point bend",
        "lot": "not printed on this slide; the first lot characterised"
      },
      "method": "Average printed in a 4-point bend table at NASA Glenn Research Center",
      "status": "ground",
      "source": "nasa-2020-bn",
      "where": "Flexural Testing (cont.) table, row HP parallel, column Average at 600 C",
      "source_detail": {
        "title": "Lot-to-lot Variability of BN Grades for Space Electric Propulsion Applications (Mackey, Salem, Stanford, Kamhawi, McEnerney, Hofer)",
        "id": "NTRS 20200000860, 2020",
        "url": "https://ntrs.nasa.gov/citations/20200000860",
        "year": 2020,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "flexural_strength",
      "label": "Flexural strength at 600 °C, hot-pressed HP grade, perpendicular to pressing",
      "value": 70.1,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "HP (Saint-Gobain BN with calcium borate binder)",
        "temperature": "600 °C",
        "direction": "perpendicular to hot-press direction",
        "test": "4-point bend",
        "lot": "not printed on this slide; the first lot characterised"
      },
      "method": "Average printed in a 4-point bend table at NASA Glenn Research Center",
      "status": "ground",
      "source": "nasa-2020-bn",
      "where": "Flexural Testing (cont.) table, row HP perpendicular, column Average at 600 C",
      "source_detail": {
        "title": "Lot-to-lot Variability of BN Grades for Space Electric Propulsion Applications (Mackey, Salem, Stanford, Kamhawi, McEnerney, Hofer)",
        "id": "NTRS 20200000860, 2020",
        "url": "https://ntrs.nasa.gov/citations/20200000860",
        "year": 2020,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "weibull_modulus",
      "label": "Weibull modulus of flexural strength at 25 °C, hot-pressed HP grade, parallel to pressing",
      "value": 19.3,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "grade": "HP (Saint-Gobain BN with calcium borate binder)",
        "temperature": "25 °C",
        "direction": "parallel to hot-press direction"
      },
      "method": "Printed Weibull modulus from a 4-point bend table at NASA Glenn Research Center; name not in the canonical property file",
      "status": "ground",
      "source": "nasa-2020-bn",
      "where": "Flexural Testing (cont.) table, row HP parallel, column Weibull Modulus at room temperature",
      "source_detail": {
        "title": "Lot-to-lot Variability of BN Grades for Space Electric Propulsion Applications (Mackey, Salem, Stanford, Kamhawi, McEnerney, Hofer)",
        "id": "NTRS 20200000860, 2020",
        "url": "https://ntrs.nasa.gov/citations/20200000860",
        "year": 2020,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "weibull_modulus",
      "label": "Weibull modulus of flexural strength at 25 °C, hot-pressed HP grade, perpendicular to pressing",
      "value": 22.3,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "grade": "HP (Saint-Gobain BN with calcium borate binder)",
        "temperature": "25 °C",
        "direction": "perpendicular to hot-press direction"
      },
      "method": "Printed Weibull modulus from a 4-point bend table at NASA Glenn Research Center; name not in the canonical property file",
      "status": "ground",
      "source": "nasa-2020-bn",
      "where": "Flexural Testing (cont.) table, row HP perpendicular, column Weibull Modulus at room temperature",
      "source_detail": {
        "title": "Lot-to-lot Variability of BN Grades for Space Electric Propulsion Applications (Mackey, Salem, Stanford, Kamhawi, McEnerney, Hofer)",
        "id": "NTRS 20200000860, 2020",
        "url": "https://ntrs.nasa.gov/citations/20200000860",
        "year": 2020,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "porosity",
      "label": "Porosity, hot-pressed HP grade",
      "value": 14,
      "bound": "upper",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "grade": "HP (Saint-Gobain BN with calcium borate binder)",
        "printed_value": "<14",
        "method_in_source": "ASTM C830"
      },
      "method": "Upper bound printed in a table at NASA Glenn Research Center; name not in the canonical property file",
      "status": "ground",
      "source": "nasa-2020-bn",
      "where": "General Properties Overview (cont.), table Property trends in BN/SiO2 content, row Porosity, column HP",
      "source_detail": {
        "title": "Lot-to-lot Variability of BN Grades for Space Electric Propulsion Applications (Mackey, Salem, Stanford, Kamhawi, McEnerney, Hofer)",
        "id": "NTRS 20200000860, 2020",
        "url": "https://ntrs.nasa.gov/citations/20200000860",
        "year": 2020,
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "density",
      "label": "Density, h-BN material (not a grade)",
      "value": 2.1,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "form": "hexagonal BN, material-level value, not a grade",
        "temperature": "not stated",
        "unit_in_source": "2.1 g/cm3 (h-BN)"
      },
      "method": "Value in the Properties infobox of the Wikipedia article on boron nitride",
      "status": "ground",
      "source": "wiki-bn",
      "where": "Infobox, Properties, Density row, h-BN value",
      "source_detail": {
        "title": "Boron nitride, Wikipedia",
        "url": "https://en.wikipedia.org/wiki/Boron_nitride",
        "kind": "web",
        "license": "CC BY-SA, cited not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity parallel to basal planes, h-BN material (not a grade)",
      "value": 600,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "form": "hexagonal BN, material-level value, parallel to the basal planes",
        "temperature": "not stated"
      },
      "method": "Value printed in the Physical properties table of the Wikipedia article on boron nitride, in the h-BN row",
      "status": "ground",
      "source": "wiki-bn",
      "where": "Properties, Physical, thermal conductivity table, h-BN row, parallel value",
      "source_detail": {
        "title": "Boron nitride, Wikipedia",
        "url": "https://en.wikipedia.org/wiki/Boron_nitride",
        "kind": "web",
        "license": "CC BY-SA, cited not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity perpendicular to basal planes, h-BN material (not a grade)",
      "value": 30,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "form": "hexagonal BN, material-level value, perpendicular to the basal planes",
        "temperature": "not stated"
      },
      "method": "Value printed in the Physical properties table of the Wikipedia article on boron nitride, in the h-BN row",
      "status": "ground",
      "source": "wiki-bn",
      "where": "Properties, Physical, thermal conductivity table, h-BN row, perpendicular value",
      "source_detail": {
        "title": "Boron nitride, Wikipedia",
        "url": "https://en.wikipedia.org/wiki/Boron_nitride",
        "kind": "web",
        "license": "CC BY-SA, cited not reproduced"
      }
    },
    {
      "benchmark": "first_oxidation_temperature",
      "label": "Temperature of first oxidation in ambient air, 20 min, h-BN single crystal",
      "value": 900,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "form": "(0001) h-BN single crystal, not a hot-pressed grade",
        "atmosphere": "ambient air",
        "exposure": "20 minutes",
        "detection": "AFM and SEM/EDS"
      },
      "method": "Abstract of an AFM and SEM/EDS study; name not in the canonical property file. The value is a first sign of oxidation, not a service limit",
      "status": "ground",
      "source": "khan2019-hbn-oxidation",
      "where": "Abstract, first sentence on oxidation at 900 C for 20 minutes",
      "source_detail": {
        "title": "Hexagonal Boron Nitride Single Crystal Thermal Oxidation and Etching in Air: An Atomic Force Microscopy Study (Khan, Nour, Mondoux, Liu, Edgar, Berta)",
        "id": "DOI 10.1557/adv.2018.667, MRS Advances 4(10), 601-608",
        "url": "https://www.cambridge.org/core/journals/mrs-advances/article/abs/hexagonal-boron-nitride-single-crystal-thermal-oxidation-and-etching-in-air-an-atomic-force-microscopy-study/A25F5711618A9A69FBDD989C3BDBBFC8",
        "year": 2019,
        "kind": "paper",
        "license": "Materials Research Society, abstract read, cited not reproduced"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Ambient air at high temperature",
      "headline": "Oxidation of h-BN in air first shows at about 900 °C after 20 minutes, as shallow pits.",
      "effect": "On (0001) single crystals in ambient air, the first evidence of oxidation was shallow hexagonal pits under 100 nm across and several nanometres deep at 900 °C for 20 minutes. At 1100 °C for 20 minutes the pits reached 1.0 to 2.0 µm, and the surface formed boron and oxygen particles.",
      "rating": "moderate",
      "conditions": {
        "form": "(0001) h-BN single crystal, not a hot-pressed grade",
        "atmosphere": "ambient air",
        "exposure": "20 minutes at each temperature"
      },
      "source": "khan2019-hbn-oxidation",
      "where": "Abstract"
    },
    {
      "environment": "Water vapour and humidity",
      "headline": "Strength and elastic modulus of hot-pressed h-BN are moisture sensitive, and the sensitivity differs between lots.",
      "effect": "NASA lists flexural strength and elastic modulus among the properties with significant lot-to-lot variation, and says Lot 2 is more moisture sensitive. The moisture absorption and density show minimal lot-to-lot variation. The moisture-soak strength numbers are in the slides but are not used as values in this profile.",
      "rating": "moderate",
      "conditions": {
        "grades": "HP, M26, M (Saint-Gobain)",
        "test": "soak in a humidity chamber and submerged in water at 25 °C, then 4-point bend"
      },
      "source": "nasa-2020-bn",
      "where": "Moisture Sensitivity slides and Summary slide"
    },
    {
      "environment": "Electric propulsion plasma and back-sputtered deposition",
      "headline": "Plasma erosion and back-sputtered deposition are the tested failure modes for electric propulsion; no erosion rate was found.",
      "effect": "NASA lists plasma erosion, high temperature, low temperature, vacuum and back-sputtered deposition as harsh conditions that electric propulsion ceramics may face. The sources read give no erosion rate or secondary electron yield value for hot-pressed h-BN.",
      "rating": "unknown",
      "conditions": {
        "environment": "electric propulsion, plasma",
        "erosion_rate": "not found in the sources read"
      },
      "source": "nasa-2020-bn",
      "where": "Introduction, Electric Propulsion slide and Factors of Interest slide"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "PubChem aggregates ECHA C&L notifications for boron nitride. Of 480 company reports, 422 (87.9 %) say the substance does not meet GHS criteria. Of the reports that give codes, 11.7 % list H319 (causes serious eye irritation) and 10.8 % list H335 (may cause respiratory irritation). Signal word Warning. The record notes that the classification varies with impurities and additives.",
        "ghs": [
          "H319",
          "H335"
        ],
        "source": "pubchem-bn",
        "where": "9.1.1 GHS Classification, ECHA C&L Notifications Summary"
      },
      {
        "text": "PubChem summarises the cosmetic review of boron nitride (CIR, 2015) as safe in the present practices of use and concentration. This is a cosmetic use conclusion, not a workplace limit.",
        "ghs": [],
        "source": "pubchem-bn",
        "where": "10.1.1 Toxicity Summary, Cosmetic Ingredient Review Finding"
      }
    ],
    "failure_risks": [
      {
        "mode": "Bending failure at high temperature, parallel to pressing",
        "trigger": "Load applied parallel to the hot-press direction of the HP grade at 600 °C",
        "consequence": "Average bending strength falls from 39.7 MPa at 25 °C to 9.8 MPa at 600 °C. NASA also notes significant deflection of HP at 600 °C, and suggests a CaF2 or calcium borate related mechanism.",
        "severity": "high",
        "source": "nasa-2020-bn",
        "where": "Flexural Testing slides, HP parallel row"
      },
      {
        "mode": "Strength depends on hot-press orientation",
        "trigger": "Part orientation relative to the hot-press axis is not controlled",
        "consequence": "HP bending strength is 39.7 MPa parallel and 70.5 MPa perpendicular at 25 °C, while Grade A gives 94 MPa parallel and 65 MPa perpendicular. The grades reverse the trend, so one orientation rule cannot be assumed.",
        "severity": "moderate",
        "source": "pc-uk-grade-a",
        "where": "Material datasheet, Mechanical block, Flexural Strength row"
      },
      {
        "mode": "Brittle failure at room temperature",
        "trigger": "Loading of any tested grade at room temperature",
        "consequence": "NASA reports that all grades tested, HP, M and M26, failed in a brittle manner at 25 °C, so no yield or plastic warning should be assumed.",
        "severity": "moderate",
        "source": "nasa-2020-bn",
        "where": "Flexural Testing slide"
      },
      {
        "mode": "Oxidation pitting in air",
        "trigger": "Sustained exposure in ambient air near or above 900 °C",
        "consequence": "Shallow pits form first; at 1100 °C for 20 minutes they are 1 to 2 µm across. The effect on strength is not measured in the sources read.",
        "severity": "moderate",
        "source": "khan2019-hbn-oxidation",
        "where": "Abstract"
      },
      {
        "mode": "Lot-to-lot variation",
        "trigger": "Change of production lot",
        "consequence": "NASA finds significant lot-to-lot variation in flexural strength and elastic modulus, and says only two lots have been characterised so far.",
        "severity": "moderate",
        "source": "nasa-2020-bn",
        "where": "Summary slide"
      }
    ],
    "side_effects": [],
    "handling": [
      {
        "text": "Specify the grade, the hot-press direction and the lot number, because strength and modulus change with direction and lot.",
        "source": "nasa-2020-bn",
        "where": "General Properties Overview, Hot Press Direction slide, and Summary slide"
      },
      {
        "text": "Keep the part below 850 °C in air for Grade A; the 1200 °C figure is for an inert atmosphere only.",
        "source": "pc-uk-grade-a",
        "where": "Material datasheet, Thermal block, Maximum Temperature rows"
      },
      {
        "text": "Limit dust. PubChem lists precautionary codes P261 (avoid breathing dust), P271 (use outdoors or in a well-ventilated area) and P280 (wear protective equipment) among the codes reported for boron nitride.",
        "source": "pubchem-bn",
        "where": "9.1.1 GHS Classification, Precautionary Statement Codes"
      }
    ],
    "mitigations": []
  },
  "uses": [
    {
      "application": "propulsion-and-tanks",
      "device": "Insulators and components in space electric propulsion",
      "example": "NASA Glenn and JPL tested commercially available hot-pressed h-BN grades for space electric propulsion, where components must provide electrical isolation, thermal isolation or limited structural support. The report tests grades for lot-to-lot consistency; it does not state which grade flew.",
      "source": "nasa-2020-bn",
      "where": "Title, Introduction and Materials of Interest slides"
    },
    {
      "application": "electronics-and-chips",
      "device": "High-voltage electrical insulator with high thermal conductivity",
      "example": "NASA Glenn describes an exfoliated h-BN and alumina ceramic composite of about 60 wt % h-BN as potentially a high thermal conductivity electrical insulator. The composite is a related material, not the grades listed in properties.",
      "source": "nasa-2017-hbn",
      "where": "Summary and Introduction"
    },
    {
      "application": "electronics-and-chips",
      "device": "Microwave components and high-temperature electrical insulators",
      "example": "Precision Ceramics lists microwave components, high-temperature electrical insulators, radar components, setter plates, crucibles and metal spraying nozzles as applications of its hot-pressed Grade A.",
      "source": "pc-uk-grade-a",
      "where": "Overview and Applications block"
    },
    {
      "application": "mechanisms",
      "device": "Solid lubricant",
      "example": "Wikipedia says h-BN is a good lubricant at low and high temperatures, usable up to 900 °C including in oxidizing atmospheres, and that its lubricity does not depend on trapped water or gas, so it can be used in vacuum, including space applications.",
      "source": "wiki-bn",
      "where": "Applications, Hexagonal BN paragraph"
    }
  ],
  "supply": [
    {
      "subject": "Boron feedstock for h-BN (borates)",
      "abundance": "USGS 2026: Turkey produced 1,500 thousand metric tons of refined borates in 2025 (1,800 in 2024) and holds reserves of 950,000 thousand metric tons, the largest in the table. The United States reports reserves of 48,000 thousand metric tons. Turkey supplied 90 % of U.S. boron imports in 2021 to 2024.",
      "producers": [],
      "critical_lists": [
        {
          "list": "U.S. Final 2025 List of Critical Minerals (boron added in 2025)",
          "listed": true
        }
      ],
      "substitutes": [],
      "source": "usgs-mcs2026-boron",
      "where": "Salient Statistics, Import Sources, World Production and Reserves table, Critical minerals paragraph"
    },
    {
      "subject": "Producers named for hot-pressed h-BN grades in the sources read",
      "abundance": "NASA 2020 lists Saint-Gobain (HP, M26, M), Kennametal (BN-XX) and Tokuyama or Precision Ceramics (Hi-M). Precision Ceramics UK sells Grade A. NASA 2017 used Momentive PT110 powder as the h-BN starting material. Stanford Advanced Materials is a distributor of hot-pressed BN.",
      "producers": [],
      "critical_lists": [],
      "substitutes": [],
      "source": "nasa-2020-bn",
      "where": "Materials of Interest table, Vendor column; the Momentive note is in nasa-2017-hbn, Experimental section"
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "Wikipedia: Boron nitride (structure, physical properties, applications)",
      "type": "database",
      "url": "https://en.wikipedia.org/wiki/Boron_nitride"
    },
    {
      "title": "PubChem compound record CID 66227: Boron nitride, GHS classification and identifiers",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Boron-nitride"
    },
    {
      "title": "Lot-to-lot Variability of BN Grades for Space Electric Propulsion Applications (Mackey et al., NASA Glenn and JPL, 2020, NTRS 20200000860)",
      "type": "report",
      "url": "https://ntrs.nasa.gov/citations/20200000860",
      "year": 2020
    },
    {
      "title": "Synthesis and Thermal Conductivity of Exfoliated Hexagonal Boron Nitride/Alumina Ceramic Composite (NASA/TM-2017-219472)",
      "type": "report",
      "url": "https://ntrs.nasa.gov/api/citations/20170003135/downloads/20170003135.pdf",
      "year": 2017
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026: Boron",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-boron.pdf",
      "year": 2026
    },
    {
      "title": "Khan et al., Hexagonal Boron Nitride Single Crystal Thermal Oxidation and Etching in Air: An AFM Study, MRS Advances 4(10), 2019",
      "type": "paper",
      "url": "https://www.cambridge.org/core/journals/mrs-advances/article/abs/hexagonal-boron-nitride-single-crystal-thermal-oxidation-and-etching-in-air-an-atomic-force-microscopy-study/A25F5711618A9A69FBDD989C3BDBBFC8",
      "year": 2019
    },
    {
      "title": "Precision Ceramics UK material datasheet: Boron Nitride (BN) Grade A",
      "type": "datasheet",
      "url": "https://precision-ceramics.com/wp-content/uploads/2018/07/Boron-Nitride-Grade-A-Technical-Data-Sheet-en.pdf"
    },
    {
      "title": "Stanford Advanced Materials: Hot Pressed Boron Nitride Crucible specification table (BN99 AX05, BN-BO Grade A, BNCB Grade HP)",
      "type": "datasheet",
      "url": "https://samaterials.com/boron-nitride/1659-boron-nitride-crucible.html"
    }
  ],
  "gaps": [
    "Momentive PT110 powder datasheet and the Saint-Gobain boron nitride technical pages returned HTTP 403 and were not read. No Saint-Gobain or Momentive value is recorded for any grade.",
    "The NASA 2020 density table is ambiguous in the extracted PDF text (geometric, Archimedes and porosimetry columns are not separable), so no HP density is recorded. Grade A density is used instead.",
    "The NASA Lot 1 thermal block also gives HP conductivity at 700 °C (26 W/m-K) and specific heat at 100 °C (1000 and 988 J/kg-K), and an emissivity table, but the extracted text mixes Lot 1 and Lot 2 blocks, so these are left out.",
    "Thermal conductivity of Grade A and HP at elevated temperature was not recorded: the datasheet gives no temperature for its conductivity row.",
    "Flexural strength of the HP grade on the NASA slide: sample condition (as-machined, dry oven or humidity chamber) and lot are not separated in the table. The moisture-soak strength values were not recorded.",
    "Production route of h-BN powder and hot-pressed blanks was not found in a readable source. The Wikipedia page was read for structure, applications and reference titles only; its synthesis text was not reachable in the fetched excerpt.",
    "Fracture toughness, compressive strength of the HP and M grades, and any h-BN-specific hardness value were not found in the sources read.",
    "Erosion rate, secondary electron emission yield and outgassing (total mass loss) for hot-pressed h-BN in space were not found; the NASA 2020 report lists these as factors of interest but the numbers were not in the text read.",
    "Weibull modulus, porosity, emissivity and first-oxidation temperature are not in the canonical property file. The first two names are used as printed; the first-oxidation name is first_oxidation_temperature. Check against property-canon.yaml before import.",
    "Density and thermal conductivity from Wikipedia are material-level values for h-BN and not for any hot-pressed grade; they are labelled as such.",
    "The SAM density and compressive strength values for hot-pressed grades are labelled by SAM as theoretical values and were not recorded.",
    "The NASA 2017 hBN/alumina composite values (86 and 18 W/mK at room temperature, density 2.45 g/cm3) are for a composite of about 60 wt % h-BN and 40 wt % alumina and are not recorded as h-BN properties.",
    "Tags: no tags.environments entry, because no fetched source ties hot-pressed h-BN to a named orbital or planetary environment.",
    "Designations: no AISI, UNS, EN, DIN, JIS or AFNOR code exists for hexagonal BN in the sources read. Trade-name designations only, and PT110 is a powder feedstock, not a dense ceramic.",
    "Atomic weights of boron and nitrogen were not read in this run, so the recipe lists atom counts only. PubChem prints a molecular weight of 24.82 g/mol for BN.",
    "Grade A dissipation factor at 1 MHz (printed as 1.2E-3 parallel and 3.4E-3 perpendicular) was removed because the printed scientific notation did not match the value check; the datasheet value is not recorded."
  ],
  "story": {
    "why": "h-BN is an electrical insulator that also conducts heat well for an insulator. In Precision Ceramics Grade A, a hot-pressed grade, the dielectric strength is 88 kV/mm and the thermal conductivity is 30 W/(m·K) parallel and 34 W/(m·K) perpendicular to pressing. Its air limit is 850 °C. These properties suit microwave parts and high-temperature insulators. NASA tested hot-pressed h-BN grades for space electric propulsion, where parts must insulate electrically and thermally.",
    "uses": [
      {
        "where": "Electric propulsion",
        "line": "NASA Glenn and JPL tested several commercial hot-pressed h-BN grades for space electric propulsion, where parts must insulate electrically and thermally."
      },
      {
        "where": "Microwave and high-temperature insulators",
        "line": "Precision Ceramics lists microwave components, radar components and high-temperature electrical insulators among the uses of Grade A."
      },
      {
        "where": "Solid lubricant",
        "line": "Wikipedia says h-BN is a good lubricant up to 900 °C, including in oxidizing atmospheres and in vacuum."
      }
    ],
    "can_do": [
      {
        "label": "Insulate electrically",
        "line": "Grade A has a DC dielectric strength of 88 kV/mm, and a dielectric constant of 4.6 parallel and 4.2 perpendicular at 1 MHz.",
        "benchmark": "dielectric_strength",
        "scope": "material",
        "value": "88 kV/mm"
      },
      {
        "label": "Carry heat",
        "line": "Grade A conducts heat at 30 W/(m·K) parallel and 34 W/(m·K) perpendicular to pressing. The NASA HP grade gives 33 and 31 W/(m·K).",
        "benchmark": "thermal_conductivity",
        "scope": "material",
        "value": "30 to 34 W/(m·K)"
      },
      {
        "label": "Work hot",
        "line": "Grade A is rated to 850 °C in air and 1200 °C in an inert atmosphere, per the datasheet. These are manufacturer figures, not component allowables.",
        "benchmark": "max_service_temp",
        "scope": "material",
        "value": "850 °C in air"
      }
    ],
    "compare": "In this profile the in-plane thermal conductivity of hot-pressed grades, 30 to 34 W/(m·K) for Grade A and 33 for HP, is about one-twentieth of the 600 W/(m·K) that Wikipedia gives for h-BN along the basal planes. Pressing and binder content set how much of that ideal conductivity a grade keeps. The strength also changes most with direction: Grade A reaches 94 MPa parallel and 65 MPa perpendicular, while the HP grade reverses that order at 39.7 and 70.5 MPa.",
    "compare_rows": [
      {
        "label": "Density",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Thermal conductivity",
        "benchmark": "thermal_conductivity",
        "scope": "material"
      },
      {
        "label": "Flexural strength",
        "benchmark": "flexural_strength",
        "scope": "material"
      }
    ],
    "handling": [
      "Name the grade, the hot-press direction and the lot, because strength and conductivity change with each.",
      "Keep Grade A below 850 °C in air. Above about 900 °C in air, single crystals oxidise.",
      "Limit dust. PubChem lists precautionary codes for dust and eye protection."
    ],
    "good_for": [
      "Electrical insulation at high temperature: 88 kV/mm dielectric strength in Grade A.",
      "Heat conduction in an insulator: 30 to 34 W/(m·K) in Grade A, and 600 W/(m·K) along the basal planes of h-BN.",
      "Lubrication up to 900 °C, including in vacuum."
    ],
    "watch_out": [
      "Hot strength: HP bending strength parallel to pressing is 9.8 MPa at 600 °C, against 39.7 MPa at 25 °C.",
      "Direction and lot: strength changes with pressing direction and between lots, and the trend reverses between grades.",
      "Oxidation: single crystals show pits in air from 900 °C after 20 minutes.",
      "Moisture: NASA reports moisture sensitivity of flexural strength and modulus, most in one lot.",
      "No erosion yield, outgassing or radiation value for hot-pressed h-BN was found in the sources read, so space-environment durability is not established here."
    ],
    "verdict": "Hot-pressed h-BN is an insulator that resists thermal shock, with 88 kV/mm dielectric strength and an 850 °C air limit for Grade A. Its strength depends strongly on pressing direction, lot and temperature, and it oxidises in air from about 900 °C. NASA has tested grades for electric propulsion, but no space-environment erosion or outgassing number is in this profile.",
    "recipe": {
      "line": "h-BN is the hexagonal form of boron nitride, with boron and nitrogen bonded in layers and van der Waals forces between layers. Its density is 2.1 g/cm3 (Wikipedia). BN has a molar mass of 24.82 g/mol (PubChem). Hot-pressed ceramic grades are made by hot pressing h-BN powder with a binder: NASA's HP grade contains a calcium borate binder and a BN phase of 98 wt % by Rietveld refinement, and Stanford Advanced Materials lists the Grade A binder as B2O3 (SAM).",
      "parts": [
        {
          "name": "Boron",
          "symbol": "B",
          "role": "One boron atom per formula unit, bonded to nitrogen within each layer"
        },
        {
          "name": "Nitrogen",
          "symbol": "N",
          "role": "One nitrogen atom per formula unit, bonded to boron within each layer"
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "The classification depends on who notified it, and the sources do not give exposure limits.",
        "points": [
          {
            "label": "Boron nitride as a substance",
            "line": "Of 480 company reports to the European chemicals agency, 422 say it does not meet GHS criteria. Among those that gave codes, H319 (serious eye irritation, 11.7 %) and H335 (respiratory irritation, 10.8 %) are the most common."
          },
          {
            "label": "Cosmetic use",
            "line": "The cosmetic review summarised by PubChem finds it safe in present practices of use and concentration."
          }
        ],
        "level": 1,
        "verdict": "Mixed notifications"
      },
      {
        "title": "If it fails",
        "lead": "These failures are from the sources read. The bending data are measured at NASA, the oxidation data are from a single crystal study.",
        "points": [
          {
            "label": "Hot strength",
            "line": "HP bending strength parallel to pressing falls from 39.7 MPa at 25 °C to 9.8 MPa at 600 °C."
          },
          {
            "label": "Air",
            "line": "In ambient air, single h-BN crystals first show oxidation pits at 900 °C after 20 minutes."
          },
          {
            "label": "Lot change",
            "line": "NASA finds that flexural strength and elastic modulus vary significantly between lots, so a grade name alone does not fix the strength."
          }
        ]
      },
      {
        "title": "Handling and storage",
        "points": [
          {
            "label": "Specify direction and lot",
            "line": "Strength differs parallel and perpendicular to pressing, and between lots. Name the grade, the pressing direction and the lot."
          },
          {
            "label": "Temperature",
            "line": "Grade A is rated to 850 °C in air and 1200 °C in inert atmosphere."
          }
        ]
      }
    ]
  },
  "updated": "2026-10-26",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 34,
    "unreachable": 2,
    "caveats": 5,
    "note": "Values were read by an AI assistant on 2026-10-26 from the datasheet PDF, NASA report PDF and the web pages named in each entry. Unreachable: Momentive PT110 datasheet and Saint-Gobain boron nitride pages (HTTP 403). Caveats: Grade A datasheet values are mean and typical values, not guarantees; NASA HP values are from one lot with lot ambiguity on some slides; Wikipedia values are material-level and not grade-level; the first-oxidation value is from a single crystal, not a hot-pressed grade; the 1,500 thousand t Turkey figure is USGS production of refined borates, not h-BN production."
  },
  "sources": {
    "wiki-bn": {
      "title": "Boron nitride, Wikipedia",
      "url": "https://en.wikipedia.org/wiki/Boron_nitride",
      "kind": "web",
      "license": "CC BY-SA, cited not reproduced"
    },
    "pubchem-bn": {
      "title": "PubChem compound record: Boron Nitride, CID 66227 (ECHA C&L Inventory classification, identifiers and uses)",
      "id": "CAS 10043-11-5, EC 233-136-6",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Boron-nitride",
      "kind": "database",
      "license": "PubChem (NCBI), public domain; sections attributed to ECHA, CIR and others"
    },
    "nasa-2020-bn": {
      "title": "Lot-to-lot Variability of BN Grades for Space Electric Propulsion Applications (Mackey, Salem, Stanford, Kamhawi, McEnerney, Hofer)",
      "id": "NTRS 20200000860, 2020",
      "url": "https://ntrs.nasa.gov/citations/20200000860",
      "year": 2020,
      "kind": "report",
      "license": "public domain (NASA)"
    },
    "nasa-2017-hbn": {
      "title": "Synthesis and Thermal Conductivity of Exfoliated Hexagonal Boron Nitride/Alumina Ceramic Composite (Hung, Hurst, Santiago, Lizcano, Kelly)",
      "id": "NASA/TM-2017-219472, NTRS 20170003135",
      "url": "https://ntrs.nasa.gov/api/citations/20170003135/downloads/20170003135.pdf",
      "year": 2017,
      "kind": "report",
      "license": "public domain (NASA)"
    },
    "usgs-mcs2026-boron": {
      "title": "Mineral Commodity Summaries 2026, Boron",
      "id": "USGS MCS 2026",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-boron.pdf",
      "year": 2026,
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "khan2019-hbn-oxidation": {
      "title": "Hexagonal Boron Nitride Single Crystal Thermal Oxidation and Etching in Air: An Atomic Force Microscopy Study (Khan, Nour, Mondoux, Liu, Edgar, Berta)",
      "id": "DOI 10.1557/adv.2018.667, MRS Advances 4(10), 601-608",
      "url": "https://www.cambridge.org/core/journals/mrs-advances/article/abs/hexagonal-boron-nitride-single-crystal-thermal-oxidation-and-etching-in-air-an-atomic-force-microscopy-study/A25F5711618A9A69FBDD989C3BDBBFC8",
      "year": 2019,
      "kind": "paper",
      "license": "Materials Research Society, abstract read, cited not reproduced"
    },
    "pc-uk-grade-a": {
      "title": "Precision Ceramics UK, Material Datasheet: Boron Nitride (BN) Grade A",
      "url": "https://precision-ceramics.com/wp-content/uploads/2018/07/Boron-Nitride-Grade-A-Technical-Data-Sheet-en.pdf",
      "year": 2018,
      "kind": "datasheet",
      "license": "Manufacturer datasheet, cited not reproduced"
    },
    "sam-bn-hp": {
      "title": "Stanford Advanced Materials, Hot Pressed Boron Nitride Crucible, specification table (BN99 AX05, BN-BO Grade A, BNCB Grade HP)",
      "url": "https://samaterials.com/boron-nitride/1659-boron-nitride-crucible.html",
      "kind": "web",
      "license": "Supplier web page, cited not reproduced"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/boron-nitride/"
}