Cubic boron nitride cBN

spore: profile
id: cubic-boron-nitride
spore_version: 0.2
family: carbide-nitride-boride-ceramics
name: Cubic boron nitride
abbreviation: cBN
role: superabrasive and heat-spreading ceramic
category: ceramics
type: nitrides
summary: |
  Cubic boron nitride (cBN, also written c-BN) is the cubic form of boron nitride, with a sphalerite lattice like diamond. Nanografi gives a Vickers hardness of 33 to 45 GPa for commercial polycrystalline cBN with micrometre grains. Wikipedia gives a density of 3.45 g/cm3 for c-BN. A chemical record for CAS 10043-11-5 says cBN oxidises in air above 1100 °C, while Nanografi says a protective B2O3 layer prevents further oxidation up to 1300 °C, so the two sources disagree on the oxidation limit.
best_for: Grinding and machining hardened steel with a superabrasive (Wikipedia and Superabrasives Powder), and heat spreading where the 3.45 g/cm3 density and 2.1 refractive index are design inputs
weakest_at: Oxidation in air above about 1100 °C, and a hardness that depends strongly on whether the material is pure polycrystalline cBN or a sintered compact with binder
identity:
  formula: BN, cubic boron nitride (one boron and one nitrogen atom per formula unit, in a cubic sphalerite lattice like diamond)
  cas: 10043-11-5
  crystal_system: cubic
  space_group: F43m
  source: wiki-cbn
  where: 'Infobox and structure section: space group F43m and sphalerite structure; the CAS number is listed for boron nitride in general (ChemicalBook record, Wikipedia infobox)'
  designations:
    - system: Trade name
      code: Borazon
      note: Trade name for cubic BN; the source attributes it to Diamond Innovations
      source: nanografi-cbn
      where: Closing paragraph on trade names
    - system: Trade name
      code: Cubonite
      note: Trade name for cubic BN, listed as from Russian vendors
      source: nanografi-cbn
      where: Closing paragraph on trade names
    - system: Trade name
      code: Elbor
      note: Trade name for cubic BN, listed as from Russian vendors
      source: nanografi-cbn
      where: Closing paragraph on trade names
tags:
  environments: []
  stresses:
    - extreme-heat
  applications:
    - mechanisms
    - electronics-and-chips
properties:
  - benchmark: vickers_hardness
    label: Vickers hardness, commercial polycrystalline cBN with micrometre grains
    value: 33
    value_high: 45
    unit: GPa
    scope: material
    conditions:
      form: polycrystalline cBN with micrometre grains (commercial)
      test: Vickers (HV), as printed
      temperature: not stated
      unit_in_source: GPa
    method: Range printed in a supplier article on cBN nanopowders; the load is not stated in the passage read
    status: ground
    source: nanografi-cbn
    where: Hardness paragraph, sentence giving 33-45 GPa Vickers hardness (HV)
  - benchmark: vickers_hardness
    label: Vickers microhardness, polycrystalline cBN layer in a sintered compact (first example)
    value: 3000
    value_high: 3200
    unit: kg/mm2
    scope: material
    conditions:
      form: polycrystalline cBN layer of a sintered compact with a cobalt-rich binder, not pure cBN
      test: Vickers, as printed
      unit_in_source: Kg/mm 2
    method: Micro hardness measurement printed in the first example of the patent description
    status: ground
    source: us-patent-5326380
    where: First example, sentence beginning Micro hardness on the polycrystalline cBN layer
  - benchmark: density
    label: Density, c-BN (cubic boron nitride)
    value: 3.45
    unit: g/cm3
    scope: material
    conditions:
      form: c-BN, cubic form
      unit_in_source: g/cm3
    method: Value printed in the Wikipedia infobox for boron nitride, where c-BN is given separately from h-BN
    status: ground
    source: wiki-cbn
    where: Infobox, density row, c-BN value
  - benchmark: density
    label: Density, beta-BN (cubic)
    value: 3480
    unit: kg/m3
    scope: material
    conditions:
      form: beta-BN (cubic)
      unit_in_source: kg.m-3
    method: Value printed in the density by polymorph entries of the chemical record for CAS 10043-11-5, which covers boron nitride in general
    status: ground
    source: chemicalbook-cas
    where: Physical properties, density by polymorph, beta-BN (cubic) entry
  - benchmark: melting_point
    label: Melting point, beta-BN (cubic)
    value: 3027
    unit: °C
    scope: material
    conditions:
      form: beta-BN (cubic)
      unit_in_source: °C
    method: Value printed in the melting point entries of the chemical record for CAS 10043-11-5, which covers boron nitride in general
    status: ground
    source: chemicalbook-cas
    where: Physical properties, melting point by polymorph, beta-BN entry, m.p. line
  - benchmark: melting_point
    label: Melting point of CBN, vendor page
    value: 3500
    unit: °C
    scope: material
    conditions:
      form: CBN, grade not stated
      unit_in_source: °C
    method: Value printed on a superabrasives vendor page; the page's comparison with diamond is internally inconsistent, so the value is kept as printed only
    status: ground
    source: superabrasives-performance
    where: Paragraph on the melting point of CBN compared with diamond
  - benchmark: sublimation_temperature
    label: Sublimation temperature of c-BN (Wikipedia infobox)
    value: 2973
    unit: °C
    scope: material
    conditions:
      form: c-BN
      pressure: not stated in the infobox
      unit_in_source: °C
    method: Value printed in the Wikipedia infobox beside the note sublimates (c-BN)
    status: ground
    source: wiki-cbn
    where: Infobox, melting or decomposition row, c-BN value
  - benchmark: refractive_index
    label: Refractive index, c-BN
    value: 2.1
    unit: '-'
    scope: material
    conditions:
      form: c-BN
      wavelength: not stated
    method: Value printed in the Wikipedia infobox, which gives a separate value for h-BN
    status: ground
    source: wiki-cbn
    where: Infobox, refractive index row, c-BN value
  - benchmark: oxidation_onset_temperature
    label: Oxidation in air, stated onset temperature (chemical record)
    value: 1100
    unit: °C
    scope: material
    conditions:
      atmosphere: air
      note: the record covers CAS 10043-11-5, which is boron nitride in general
      unit_in_source: °C
    method: Value in the stability and reactivity text of the chemical record, printed as oxidises in air above 1100 °C
    status: ground
    source: chemicalbook-cas
    where: Stability and reactivity section, oxidation sentence
  - benchmark: oxidation_protection_temperature
    label: Oxidation protection by a B2O3 layer, cBN
    value: 1300
    unit: °C
    scope: material
    conditions:
      atmosphere: oxygen or air
      mechanism: protective B2O3 layer
      unit_in_source: C
    method: Value printed in the thermal stability paragraph, which says further oxidation is prevented up to this temperature
    status: ground
    source: nanografi-cbn
    where: Thermal stability paragraph, sentence beginning Further oxidation to 1300 C is prevented
  - benchmark: thermal_stability_temperature
    label: Thermal stability of a cBN abrasive, vendor claim
    value: 1250
    value_high: 1350
    unit: °C
    scope: material
    conditions:
      form: cBN abrasive, grade not stated
      unit_in_source: degrees Celsius
    method: Range printed on a superabrasives vendor page under heat resistance; the page does not describe it as an oxidation test
    status: ground
    source: superabrasives-characteristics
    where: Heat resistance paragraph, sentence beginning can withstand temperatures of 1250-1350
  - benchmark: hbn_conversion_temperature
    label: Conversion of cBN to h-BN in nitrogen after 12 hours
    value: 1525
    unit: °C
    scope: material
    conditions:
      atmosphere: nitrogen
      time: 12 hours
      unit_in_source: °C
    method: Value printed in the thermal stability paragraph of the nanopowder article
    status: ground
    source: nanografi-cbn
    where: Thermal stability paragraph, sentence on conversion to h-BN in nitrogen after 12 hours
  - benchmark: lattice_constant
    label: Lattice constant a, cubic (fcc) BN
    value: 0.3615
    unit: nm
    scope: material
    conditions:
      structure: cubic (fcc), as printed
      unit_in_source: nm
    method: Value printed in the crystal structure entries of the chemical record for CAS 10043-11-5
    status: ground
    source: chemicalbook-cas
    where: Crystal structure entries, cubic (fcc) line
  - benchmark: synthesis_pressure
    label: Pressure for direct conversion of hexagonal BN to cBN
    value: 5
    value_high: 18
    unit: GPa
    scope: material
    conditions:
      starting_material: hexagonal BN
      process: direct conversion
      unit_in_source: GPa
    method: Range printed in the synthesis paragraph of the nanopowder article
    status: ground
    source: nanografi-cbn
    where: Synthesis paragraph, sentence on direct hBN to cBN conversion
  - benchmark: synthesis_temperature
    label: Temperature for direct conversion of hexagonal BN to cBN
    value: 1730
    value_high: 3230
    unit: °C
    scope: material
    conditions:
      starting_material: hexagonal BN
      process: direct conversion
      unit_in_source: C
    method: Range printed in the synthesis paragraph of the nanopowder article
    status: ground
    source: nanografi-cbn
    where: Synthesis paragraph, sentence on direct hBN to cBN conversion
  - benchmark: uv_emission_wavelength
    label: UV emission wavelength range of cBN with a voltage applied
    value: 215
    value_high: 250
    unit: nm
    scope: material
    conditions:
      excitation: voltage applied
      note: the source says the range applies to c-BN or h-BN
    method: Range printed in the optical paragraph of the nanopowder article
    status: ground
    source: nanografi-cbn
    where: Optical paragraph, sentence beginning UV light is emitted in 215-250 nm range
  - benchmark: chemical_resistance_temperature
    label: Temperature range of chemical resistance to ferrous metals
    value: 1500
    value_high: 1600
    unit: K
    scope: material
    conditions:
      counterpart: ferrous metals
      unit_in_source: K
    method: Range printed in the chemical stability sentence of the nanopowder article
    status: ground
    source: nanografi-cbn
    where: Chemical stability sentence, up to 1500-1600 K
  - benchmark: reducing_atmosphere_stability_temperature
    label: Stability in a reducing atmosphere, stated upper limit
    value: 1500
    unit: °C
    scope: material
    conditions:
      atmosphere: reducing
      note: the record covers CAS 10043-11-5, which is boron nitride in general
      unit_in_source: °C
    method: Value printed in the stability and reactivity text of the chemical record
    status: ground
    source: chemicalbook-cas
    where: Stability and reactivity section, sentence beginning stable in reducing atmospheres up to 1500
corrosion:
  - environment: Air at high temperature
    headline: 'Sources disagree on where cBN starts to oxidise in air: 1100 °C in a chemical record, and protection to 1300 °C in a vendor article.'
    effect: A chemical record for CAS 10043-11-5 says the material oxidises in air above 1100 °C. Nanografi says a protective B2O3 layer prevents further oxidation up to 1300 °C in oxygen or air. Neither source gives an oxidation rate or a test duration for cBN.
    rating: moderate
    conditions:
      atmosphere: air or oxygen
      exposure: not stated
    source: chemicalbook-cas
    where: Stability and reactivity section, oxidation sentence
  - environment: Nitrogen at high temperature
    headline: Heating cBN in nitrogen converts it to hexagonal BN.
    effect: Nanografi says conversion to h-BN is possible in nitrogen after 12 hours at 1525 °C. No conversion rate below that temperature was read.
    rating: moderate
    conditions:
      atmosphere: nitrogen
      time: 12 hours
    source: nanografi-cbn
    where: Thermal stability paragraph
  - environment: Ferrous metals at high temperature
    headline: cBN resists chemical attack from ferrous metals up to 1500 to 1600 K.
    effect: Nanografi says cBN is not chemically attacked by ferrous metals up to 1500-1600 K, which is why it is used for ferrous work. A vendor page says cBN does not easily react with iron-group elements, but gives no temperature for that statement.
    rating: low
    conditions:
      counterpart: ferrous metals
      temperature_range: 1500 to 1600 K
    source: nanografi-cbn
    where: Chemical stability sentence
  - environment: Water and humid air
    headline: The chemical record for CAS 10043-11-5 lists the material as hygroscopic and incompatible with water, but the record covers boron nitride in general.
    effect: ChemicalBook lists incompatibility with oxidising agents and water, and a hygroscopic note, for CAS 10043-11-5. No cBN-specific humidity or water test was read.
    rating: unknown
    conditions:
      record: CAS 10043-11-5, boron nitride in general
    source: chemicalbook-cas
    where: Stability and reactivity text
risks:
  hazards:
    - text: The chemical record for CAS 10043-11-5 prints the signal word Danger and several GHS pictograms. It lists skin irritation, serious eye damage and respiratory irritation among its hazard statements. The record covers boron nitride in general, so these are not cBN-only classifications.
      ghs:
        - H226
        - H315
        - H318
        - H335
      source: chemicalbook-cas
      where: Hazard and regulatory data section, hazard codes and signal word lines
    - text: A supplier safety data sheet for a cBN and cemented-carbide tool material prints the signal word Danger and lists cBN as a major constituent by mass. Its hazards come from the binder metals, so it is not a pure cBN classification.
      ghs: []
      source: osg-sds
      where: Section 2 signal word line, and the composition table in Section 3
  failure_risks:
    - mode: Oxidation in air at high temperature
      trigger: Sustained exposure in air above about 1100 °C
      consequence: Oxidation starts above 1100 °C according to the chemical record, or is prevented up to 1300 °C by a B2O3 layer according to Nanografi. The sources disagree, and no oxidation depth or strength loss for cBN was read.
      severity: moderate
      source: chemicalbook-cas
      where: Stability and reactivity text
    - mode: Conversion to hexagonal BN
      trigger: Heating in nitrogen
      consequence: Nanografi says cBN converts to h-BN in nitrogen after 12 hours at 1525 °C, so the cubic phase is lost at that condition.
      severity: moderate
      source: nanografi-cbn
      where: Thermal stability paragraph
    - mode: Hardness depends on the form
      trigger: Using a sintered compact with binder in place of pure polycrystalline cBN, or the reverse
      consequence: Commercial polycrystalline cBN is given 33 to 45 GPa Vickers hardness by Nanografi, while a sintered compact with a cobalt-rich binder reads 3000 to 3200 kg/mm2 in the patent example. The form must be named before a hardness value is used.
      severity: moderate
      source: nanografi-cbn
      where: Hardness paragraph
    - mode: Thermal-stability figures disagree
      trigger: Using a vendor thermal stability figure as a service limit
      consequence: A vendor article gives a thermal stability of 1250 to 1350 °C, while a chemical record gives 1100 °C as the oxidation onset. Neither is a component design allowable.
      severity: moderate
      source: superabrasives-characteristics
      where: Heat resistance paragraph
  side_effects: []
  handling:
    - text: Name the form (pure polycrystalline cBN, sintered compact or nanopowder) and the hardness test, because the sources give different values for each.
      source: nanografi-cbn
      where: Hardness paragraph and the first patent example
    - text: Keep cBN in air below the 1100 °C oxidation onset given by the chemical record, and avoid long holds in nitrogen near 1525 °C.
      source: chemicalbook-cas
      where: Stability and reactivity section
    - text: Limit dust. The chemical record lists respiratory irritation among the hazard statements for CAS 10043-11-5.
      source: chemicalbook-cas
      where: Hazard and regulatory data section
  mitigations: []
uses:
  - application: mechanisms
    device: Abrasive grains and polycrystalline cBN cutting-tool bits
    example: Wikipedia lists cBN as an abrasive, and polycrystalline cBN (PCBN) for machining steel, with cutting-tool bit material as a use.
    source: wiki-cbn
    where: Applications list
  - application: electronics-and-chips
    device: Heat spreaders
    example: Wikipedia lists heat spreaders among the uses of c-BN, next to X-ray membranes and sintered large parts. No thermal conductivity value for cBN is recorded in this profile, because the sources read give conflicting or unclear figures.
    source: wiki-cbn
    where: Applications list
  - application: electronics-and-chips
    device: Potential UV light emitters
    example: Nanografi says cBN emits UV light in the 215-250 nm range when a voltage is applied. The source does not name a finished device.
    source: nanografi-cbn
    where: Optical paragraph
supply:
  - subject: Boron feedstock (refined borates) for boron nitride
    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 figures are for refined borates, not for cBN or boron nitride powder.'
    critical_lists:
      - list: U.S. Final 2025 List of Critical Minerals (boron added in 2025)
        listed: true
    source: usgs-mcs2026-boron
    where: Critical minerals paragraph; World Production and Reserves table, row Turkey, refined borates
  - subject: cBN producers
    abundance: No readable source named a cBN producer or gave a cBN production figure. Superabrasives Powder and Nanografi are sales pages for cBN powder, not producers' production data.
    critical_lists: []
    source: nanografi-cbn
    where: Product description; no production data read
documents:
  - title: 'Wikipedia: Cubic boron nitride (structure, density, applications)'
    type: database
    url: https://en.wikipedia.org/wiki/Cubic_boron_nitride
  - title: 'ChemicalBook: boron nitride, CAS 10043-11-5, chemical properties and hazard record'
    type: database
    url: https://chemicalbook.com/CASEN_10043-11-5.htm
  - title: 'Nanografi: Cubic Boron Nitride Nanopowders, The New Diamond, Properties, and Applications'
    type: datasheet
    url: https://shop.nanografi.com/blog/cubic-boron-nitride-nanopowders-the-new-diamond-properties-and-applications/
  - title: 'Superabrasives Powder: Performance and applications of CBN abrasives'
    type: datasheet
    url: https://www.superabrasivespowder.com/performance-and-applications-of-cbn-abrasives.html
  - title: 'Superabrasives Powder: Characteristics of cubic boron nitride (CBN)'
    type: datasheet
    url: https://www.superabrasivespowder.com/news/characteristics-of-cubic-boron-nitride-cbn.html
  - title: 'US Patent 5,326,380: Synthesis of polycrystalline cubic boron nitride'
    type: paper
    url: https://patents.google.com/patent/US5326380
    year: 1994
  - title: 'USGS Mineral Commodity Summaries 2026: Boron'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-boron.pdf
    year: 2026
  - title: 'OSG safety data sheet: CBN/Cemented Carbide tool material'
    type: sds
    url: https://res.cloudinary.com/osg-usa-inc/image/upload/v1661778653/Literature/06%20-%20Other/MSDS/OSG_SDS_-_CBN_ozroe3.pdf
gaps:
  - Thermal conductivity of cBN is not recorded. The ChemicalBook and Wikipedia tables give cBN conductivity figures, but the table cells were read with uncertain column assignments, so neither is kept as a value.
  - 'A Rockwell C hardness range printed on a superabrasives vendor page is not recorded: the range does not fit the HRC scale the page names, and the page gives no load or method.'
  - A nanograined cBN hardness given in GPa on the Nanografi page is not recorded, because the hardness scale and test load are not stated in the passage read.
  - 'A cBN Vickers hardness given in VHN in a ChemicalBook table is not recorded: the test load is not printed and the table column is unclear.'
  - Band gap of c-BN is not recorded. Wikipedia lists a band gap in a table cell with an uncertain column, and ChemicalBook's band gap figure is for boron nitride in general.
  - 'Melting point is recorded from three sources that disagree: the chemical record gives 3027 °C for beta-BN, a vendor page gives 3500 °C, and Wikipedia gives 2973 °C as sublimation. Each is kept as printed; the sources do not agree on what the number measures.'
  - 'Crystal structure disagrees between sources: Wikipedia and Nanografi give sphalerite, and the ChemicalBook cubic entry gives wurtzite. The profile uses the sphalerite space group F43m from Wikipedia.'
  - 'Oxidation onset disagrees: a chemical record gives 1100 °C, Nanografi gives a 1300 °C protection limit, and a vendor page gives a thermal stability range of 1250 to 1350 °C. All three are recorded with their own conditions.'
  - The hazard codes are for CAS 10043-11-5, which covers boron nitride in general. No safety data sheet for a pure cubic BN powder was read. PubChem and ThomasSci could not be read in this run (a bot check and a refused request), and a Sigma-Aldrich sheet found in search covers a hexagonal BN ink, so it was not used.
  - Boron nitride producers and any cBN production figures were not found in a readable source. The USGS figures are for refined borates, not for cBN.
  - Element Six's cBN grade datasheets were not found in search results, so no Element Six grade value is recorded.
  - Wikipedia names Borazon with Hyperion Materials and Technologies as the vendor, while Nanografi names Diamond Innovations. Both are recorded as printed in their sources, and the profile does not choose one.
  - Atomic weights of boron and nitrogen were not read in this run, so the recipe lists atom counts only.
  - Fracture toughness, compressive strength, grain-size and grit data, dielectric values, outgassing, erosion, and radiation tolerance for cBN were not found in the sources read.
  - Properties with names outside the canonical file (vickers_hardness, sublimation_temperature, oxidation_onset_temperature, oxidation_protection_temperature, thermal_stability_temperature, hbn_conversion_temperature, lattice_constant, synthesis_pressure, synthesis_temperature, uv_emission_wavelength, chemical_resistance_temperature, reducing_atmosphere_stability_temperature) are used as printed. Check against property-canon.yaml before import.
  - The patent hardness values are for a sintered compact with a cobalt-rich binder, not for pure polycrystalline cBN. They are kept separate from the Nanografi value and not averaged.
sources:
  nanografi-cbn:
    title: 'Cubic Boron Nitride Nanopowders: The New Diamond, Properties, and Applications (Nanografi)'
    url: https://shop.nanografi.com/blog/cubic-boron-nitride-nanopowders-the-new-diamond-properties-and-applications/
    kind: web
    license: Vendor article, cited not reproduced
  superabrasives-performance:
    title: Performance and applications of CBN abrasives (Superabrasives Powder)
    url: https://www.superabrasivespowder.com/performance-and-applications-of-cbn-abrasives.html
    kind: web
    license: Vendor article, cited not reproduced
  superabrasives-characteristics:
    title: Characteristics of cubic boron nitride (CBN) (Superabrasives Powder)
    url: https://www.superabrasivespowder.com/news/characteristics-of-cubic-boron-nitride-cbn.html
    kind: web
    license: Vendor article, cited not reproduced
  chemicalbook-cas:
    title: 'ChemicalBook: boron nitride, CAS 10043-11-5, chemical properties and hazard record'
    url: https://chemicalbook.com/CASEN_10043-11-5.htm
    kind: database
    license: Chemical database record, cited not reproduced
  wiki-cbn:
    title: Cubic boron nitride, Wikipedia
    url: https://en.wikipedia.org/wiki/Cubic_boron_nitride
    kind: web
    license: CC BY-SA, cited not reproduced
  us-patent-5326380:
    title: 'US Patent 5,326,380: Synthesis of polycrystalline cubic boron nitride'
    url: https://patents.google.com/patent/US5326380
    year: 1994
    kind: report
    license: Patent document, cited not reproduced
  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)
  osg-sds:
    title: OSG safety data sheet, CBN/Cemented Carbide tool material
    url: https://res.cloudinary.com/osg-usa-inc/image/upload/v1661778653/Literature/06%20-%20Other/MSDS/OSG_SDS_-_CBN_ozroe3.pdf
    kind: datasheet
    license: Manufacturer safety data sheet, cited not reproduced
license: CC-BY-4.0
updated: '2026-11-02'
review:
  status: draft
  method: assistant
  checked_values: 18
  unreachable: 3
  caveats: 6
  note: 'Values were read by an AI assistant on 2026-11-02 from the web pages and PDFs named in each entry. Unreachable: PubChem (bot check), ThomasSci (refused), CityU cBN property page (blocked), and the MSF cBN review (refused). Caveats: the ChemicalBook and hazard records cover CAS 10043-11-5, which is boron nitride in general; the Wikipedia and ChemicalBook table cells were read with uncertain columns and are not recorded; the patent hardness is for a sintered compact with binder; vendor pages disagree on melting point, oxidation onset and crystal form; the USGS figures are for refined borates.'
story:
  recipe:
    line: 'Cubic boron nitride is the cubic form of BN, with boron and nitrogen atoms in a sphalerite lattice like diamond. It is made by converting hexagonal BN directly at high pressure and high temperature: Nanografi gives 5 to 18 GPa and 1730 to 3230 °C for the direct conversion. A patent describes a sintered polycrystalline compact made from cBN crystals, hBN powder and adjuvants, which is a different product from pure cBN.'
    parts:
      - name: Boron
        symbol: B
        role: One boron atom per formula unit, bonded to nitrogen in the cubic lattice
      - name: Nitrogen
        symbol: 'N'
        role: One nitrogen atom per formula unit, bonded to boron in the cubic lattice
  risk_groups:
    - title: For people
      lead: The classification depends on the record, and it covers boron nitride in general.
      level: 1
      verdict: Hazard codes are not cBN-only
      points:
        - label: Hazard record
          line: The chemical record for CAS 10043-11-5 prints the signal word Danger and lists skin irritation, serious eye damage and respiratory irritation.
        - label: Tool composite
          line: A tool safety data sheet that includes cBN lists it as a major constituent by mass, but its hazards come from the binder metals.
    - title: If it fails
      lead: These failures come from the sources read. The hardness and oxidation data come from different sources, so each figure is kept with its form and conditions.
      points:
        - label: Air
          line: Oxidation in air begins above 1100 °C according to the chemical record, or is prevented up to 1300 °C by a B2O3 layer according to Nanografi.
        - label: Nitrogen
          line: Nanografi says cBN converts to hexagonal BN in nitrogen after 12 hours at 1525 °C.
        - label: Form
          line: Commercial polycrystalline cBN is given 33 to 45 GPa Vickers hardness, while a sintered compact with binder reads 3000 to 3200 kg/mm2.
    - title: Handling and storage
      points:
        - label: Name the form
          line: Name the form, the hardness test and the supplier, because the sources give different values for each form.
        - label: Temperature
          line: Keep cBN below the 1100 °C oxidation onset in air, and avoid long holds in nitrogen near 1525 °C.
  why: 'Cubic boron nitride is a superabrasive ceramic. Nanografi gives a Vickers hardness of 33 to 45 GPa for commercial polycrystalline cBN, and Wikipedia gives a density of 3.45 g/cm3 for c-BN. These two values set the abrasive and heat-spreading case: hardness for grinding hardened steel, and density and oxidation limits for handling it hot.'
  uses:
    - where: Grinding and cutting tools
      line: Wikipedia lists cBN as an abrasive and polycrystalline cBN for machining steel, with cutting-tool bits as a use.
    - where: Heat spreaders
      line: Wikipedia lists heat spreaders among the uses of c-BN. No thermal conductivity value is recorded here.
    - where: UV emitters, potential
      line: Nanografi says cBN emits UV light in the 215-250 nm range when a voltage is applied. It names no finished device.
  can_do:
    - label: Machine steel as a superabrasive
      value: 33 to 45 GPa Vickers
      benchmark: vickers_hardness
      line: Wikipedia lists cBN as an abrasive and PCBN for machining steel. Nanografi gives 33 to 45 GPa Vickers hardness for commercial polycrystalline cBN.
    - label: Resist ferrous metals
      value: 1500 to 1600 K
      benchmark: chemical_resistance_temperature
      line: Nanografi says cBN resists chemical attack from ferrous metals up to 1500-1600 K.
    - label: Stay stable in reducing atmospheres
      value: 1500 °C
      benchmark: reducing_atmosphere_stability_temperature
      line: The chemical record for CAS 10043-11-5 says cBN is stable in reducing atmospheres up to 1500 °C, and the record covers boron nitride in general.
  compare: 'Density figures for cubic boron nitride differ by source: Wikipedia gives 3.45 g/cm3 for c-BN and the chemical record gives 3480 kg/m3 for beta-BN. The melting point is not settled: the chemical record gives 3027 °C, a vendor page gives 3500 °C, and Wikipedia gives 2973 °C for sublimation. The hardness depends on the form: 33 to 45 GPa Vickers for commercial polycrystalline cBN (Nanografi) and 3000 to 3200 kg/mm2 Vickers for a sintered compact with a cobalt-rich binder (patent). These numbers are reported side by side, not averaged.'
  compare_rows:
    - label: Density
      benchmark: density
    - label: Melting point
      benchmark: melting_point
    - label: Vickers hardness
      benchmark: vickers_hardness
  handling:
    - Name the form, the hardness test and the supplier, because the values differ with each.
    - Keep cBN below the 1100 °C oxidation onset in air. Nanografi puts protection to 1300 °C with a B2O3 layer, but this is not a design limit.
    - Limit dust. The hazard record lists respiratory irritation among its hazard statements.
  good_for:
    - Superabrasive grinding of hardened steel, with a Vickers hardness of 33 to 45 GPa for commercial polycrystalline grades (Nanografi).
    - Heat spreading in air up to about 1100 °C, with the oxidation limit taken from the chemical record.
    - UV emission studies at 215 to 250 nm with a voltage applied (Nanografi).
  watch_out:
    - 'Oxidation: the sources give 1100 °C and 1300 °C as the limit in air, so use the lower value unless the supplier confirms otherwise.'
    - 'Form: a sintered compact with binder reads 3000 to 3200 kg/mm2 Vickers, not the 33 to 45 GPa of commercial polycrystalline cBN.'
    - 'Nitrogen: cBN converts to hexagonal BN after 12 hours at 1525 °C.'
    - No thermal conductivity, erosion, outgassing or radiation value for cBN was recorded, so space durability is not established here.
  verdict: Cubic boron nitride is a superabrasive ceramic with a Vickers hardness of 33 to 45 GPa for commercial polycrystalline grades and a density of 3.45 g/cm3 for c-BN. Its air oxidation limit is disputed, 1100 °C in a chemical record against 1300 °C with a B2O3 layer in a vendor article, so the lower figure should be used. Hardness depends strongly on the form, so the form and test must be named with any value.