Titanium diboride TiB2

spore: profile
id: titanium-diboride
spore_version: 0.2
family: carbide-nitride-boride-ceramics
name: Titanium diboride
abbreviation: TiB2
role: hard, electrically conductive ultra-high-temperature ceramic (boride)
category: ceramics
type: ultra-high-temperature-ceramics
summary: |
  Titanium diboride is a hexagonal boride that is hard, stiff and electrically conductive. NIST's evaluated trend values for dense polycrystalline TiB2 (density 4.5 g/cm3, grain size 9 micrometres) give an elastic modulus of 565 GPa, a flexural strength of 400 MPa, a fracture toughness of 6.2 MPa·m1/2 and a Vickers hardness of 25 GPa at 20 degC, falling to 4.6 GPa at 1000 degC. A 2024 open-access review gives a melting point of 3225 degC, a hardness of 25 to 35 GPa, a thermal conductivity of 60 to 120 W/m·K and an oxidation resistance below 1200 degC. The sources disagree on flexural strength (400 MPa from NIST against 700 to 1000 MPa in the review), so both values are kept. Titanium, one of its two elements, is produced mostly in China and Japan (USGS 2026).
best_for: Hard, stiff, electrically conductive ceramic parts and wear surfaces, such as cathodes and cutting tools, where a melting point near 3225 degC matters more than oxidation resistance
weakest_at: Oxidation in air at high temperature (the review calls resistance inadequate, and B2O3 volatilises as the temperature rises, per Ozkan et al.) and brittleness (Weibull modulus of 11, NIST)
identity:
  formula: TiB2
  cas: 12045-63-5
  crystal_system: hexagonal
  space_group: P6/mmm
  source: pubchem-tib2
  where: PubChem CID 92028754 record (formula, synonyms and CAS 12045-63-5). Hexagonal P6/mmm from NIST Munro 2000, Figure 1 text.
tags:
  environments: []
  stresses:
    - extreme-heat
  applications:
    - structures
    - mechanisms
properties:
  - benchmark: density
    label: Crystal density, TiB2 (single crystal)
    value: 4.5
    unit: g/cm3
    scope: material
    conditions:
      temperature: 20 degC
      basis: single crystal, theoretical crystal density
    method: Density row of NIST Table 1, footnote d (single crystal). Not the polycrystalline density.
    status: ground
    source: nist-munro-2000
    where: Table 1, Density row, 20 degC column
  - benchmark: density
    label: Density, TiB2 (review table)
    value: 4.5
    unit: g/cm3
    scope: material
    conditions:
      basis: TiB2 column of the review's property table
    method: Table 1 of the 2024 review, Density row
    status: ground
    source: lv-tib2-2024
    where: Table 1 (Properties of TiB2 and other important high-temperature ceramics), Density row, TiB2 column
  - benchmark: melting_point
    label: Melting point, TiB2
    value: 3225
    unit: degC
    scope: material
    conditions:
      basis: TiB2 column of the review's property table
    method: Table 1 of the 2024 review, Melting point row
    status: ground
    source: lv-tib2-2024
    where: Table 1, Melting point row, TiB2 column
  - benchmark: elastic_modulus
    label: Elastic modulus, dense polycrystalline TiB2 (NIST trend value)
    value: 565
    unit: GPa
    scope: material
    conditions:
      temperature: 20 degC
      basis: trend value for density 4.5 plus or minus 0.1 g/cm3, grain size 9 plus or minus 1 micrometres, TiB2 at least 98 percent
      uncertainty: 5 percent relative standard uncertainty
    method: Mutually consistent trend values (NIST Table 1)
    status: ground
    source: nist-munro-2000
    where: Table 1, Elastic modulus row, 20 degC column
  - benchmark: elastic_modulus
    label: Elastic modulus, TiB2 (review table)
    value: 500
    value_high: 560
    bound: range
    unit: GPa
    scope: material
    conditions:
      basis: TiB2 column of the review's property table; temperature not stated
    method: Printed as 500-560 in Table 1 of the 2024 review
    status: ground
    source: lv-tib2-2024
    where: Table 1, Elastic modulus row, TiB2 column
  - benchmark: shear_modulus
    label: Shear modulus, dense polycrystalline TiB2 (NIST trend value)
    value: 255
    unit: GPa
    scope: material
    conditions:
      temperature: 20 degC
      basis: trend value, same material as the elastic modulus row
    method: Mutually consistent trend values (NIST Table 1)
    status: ground
    source: nist-munro-2000
    where: Table 1, Shear modulus row, 20 degC column
  - benchmark: bulk_modulus
    label: Bulk modulus, dense polycrystalline TiB2 (NIST trend value)
    value: 240
    unit: GPa
    scope: material
    conditions:
      temperature: 20 degC
      basis: trend value, same material as the elastic modulus row
    method: Mutually consistent trend values (NIST Table 1)
    status: ground
    source: nist-munro-2000
    where: Table 1, Bulk modulus row, 20 degC column
  - benchmark: poissons_ratio
    label: Poisson's ratio, dense polycrystalline TiB2 (NIST trend value)
    value: 0.108
    unit: unitless
    scope: material
    conditions:
      temperature: 20 degC
    method: Mutually consistent trend values (NIST Table 1)
    status: ground
    source: nist-munro-2000
    where: Table 1, Poisson's ratio row
  - benchmark: flexural_strength
    label: Flexural strength, dense polycrystalline TiB2 (NIST trend value)
    value: 400
    unit: MPa
    scope: material
    conditions:
      temperature: 20 degC
      basis: trend value, same material as the elastic modulus row
    method: Mutually consistent trend values (NIST Table 1)
    status: ground
    source: nist-munro-2000
    where: Table 1, Flexural strength row, 20 degC column
  - benchmark: flexural_strength
    label: Flexural strength, dense polycrystalline TiB2 at 1000 degC (NIST trend value)
    value: 459
    unit: MPa
    scope: material
    conditions:
      temperature: 1000 degC
      basis: trend value, same material as the elastic modulus row
    method: Mutually consistent trend values (NIST Table 1)
    status: ground
    source: nist-munro-2000
    where: Table 1, Flexural strength row, 1000 degC column
  - benchmark: flexural_strength
    label: Flexural strength, TiB2 (review table)
    value: 700
    value_high: 1000
    bound: range
    unit: MPa
    scope: material
    conditions:
      basis: TiB2 column of the review's property table; temperature and grade not stated
    method: Printed as 700-1000 in Table 1 of the 2024 review. Higher than the NIST trend value of 400 MPa; the sources do not explain the gap.
    status: ground
    source: lv-tib2-2024
    where: Table 1, Flexural strength row, TiB2 column
  - benchmark: fracture_toughness
    label: Fracture toughness, dense polycrystalline TiB2 (NIST trend value)
    value: 6.2
    unit: MPa·m1/2
    scope: material
    conditions:
      temperature: 20 degC
      basis: trend value, same material as the elastic modulus row
    method: Mutually consistent trend values (NIST Table 1); Section 3.3 gives the grain-size dependence
    status: ground
    source: nist-munro-2000
    where: Table 1, Fracture toughness row, 20 degC column
  - benchmark: fracture_toughness
    label: Fracture toughness, TiB2 (review table)
    value: 4
    value_high: 5
    bound: range
    unit: MPa·m1/2
    scope: material
    conditions:
      basis: TiB2 column of the review's property table; test method not stated
    method: Printed as 4-5 in Table 1 of the 2024 review
    status: ground
    source: lv-tib2-2024
    where: Table 1, Fracture toughness row, TiB2 column
  - benchmark: hardness
    label: Vickers hardness, dense polycrystalline TiB2 (NIST trend value)
    value: 25
    unit: GPa
    scope: material
    conditions:
      temperature: 20 degC
      load: 5 N Vickers (footnote f)
      basis: trend value, same material as the elastic modulus row
    method: Mutually consistent trend values (NIST Table 1), Vickers at 5 N load
    status: ground
    source: nist-munro-2000
    where: Table 1, Hardness row, 20 degC column; footnote f
  - benchmark: hardness
    label: Vickers hardness, dense polycrystalline TiB2 at 500 degC (NIST trend value)
    value: 11
    unit: GPa
    scope: material
    conditions:
      temperature: 500 degC
      load: 5 N Vickers
    method: Mutually consistent trend values (NIST Table 1)
    status: ground
    source: nist-munro-2000
    where: Table 1, Hardness row, 500 degC column
  - benchmark: hardness
    label: Vickers hardness, dense polycrystalline TiB2 at 1000 degC (NIST trend value)
    value: 4.6
    unit: GPa
    scope: material
    conditions:
      temperature: 1000 degC
      load: 5 N Vickers
    method: Mutually consistent trend values (NIST Table 1)
    status: ground
    source: nist-munro-2000
    where: Table 1, Hardness row, 1000 degC column
  - benchmark: hardness
    label: Hardness, TiB2 (review table)
    value: 25
    value_high: 35
    bound: range
    unit: GPa
    scope: material
    conditions:
      basis: TiB2 column of the review's property table; test method not stated
    method: Printed as 25-35 in Table 1 of the 2024 review
    status: ground
    source: lv-tib2-2024
    where: Table 1, Hardness row, TiB2 column
  - benchmark: weibull_modulus
    label: Weibull modulus, TiB2 (NIST, three reported values)
    value: 11
    unit: unitless
    scope: material
    conditions:
      basis: 'one of three reported values: 11 (sintered, 8 micrometre grain), 29 (hot pressed) and 8 (hot pressed, 15 micrometre grain)'
    method: Weibull modulus row of NIST Table 1 with footnote i; the paper says reliable values need at least 30 specimens
    status: ground
    note: Three reported values (8, 11, 29) differ widely; 11 is the value printed in the table.
    source: nist-munro-2000
    where: Table 1, Weibull modulus row, footnote i; Section 3.2
  - benchmark: thermal_conductivity
    label: Thermal conductivity, dense polycrystalline TiB2 (NIST trend value)
    value: 96
    unit: W/m·K
    scope: material
    conditions:
      temperature: 20 degC
      basis: trend value, same material as the elastic modulus row
    method: Mutually consistent trend values (NIST Table 1), derived from thermal diffusivity and specific heat
    status: ground
    source: nist-munro-2000
    where: Table 1, Thermal conductivity row, 20 degC column
  - benchmark: thermal_conductivity
    label: Thermal conductivity, dense polycrystalline TiB2 at 1000 degC (NIST trend value)
    value: 78.1
    unit: W/m·K
    scope: material
    conditions:
      temperature: 1000 degC
      basis: trend value, same material as the elastic modulus row
    method: Mutually consistent trend values (NIST Table 1)
    status: ground
    source: nist-munro-2000
    where: Table 1, Thermal conductivity row, 1000 degC column
  - benchmark: thermal_conductivity
    label: Thermal conductivity, TiB2 (review table)
    value: 60
    value_high: 120
    bound: range
    unit: W/m·K
    scope: material
    conditions:
      basis: TiB2 column of the review's property table; temperature and grade not stated
    method: Printed as 60-120 W m-1 K-1 in Table 1 of the 2024 review
    status: ground
    note: Wide range; the review's text repeats it as 60-120 W·(m·K)-1.
    source: lv-tib2-2024
    where: Table 1, Thermal conductivity row, TiB2 column
  - benchmark: specific_heat
    label: Specific heat, dense polycrystalline TiB2 (NIST trend value)
    value: 617
    unit: J/kg·K
    scope: material
    conditions:
      temperature: 20 degC
      basis: trend value, same material as the elastic modulus row
    method: Mutually consistent trend values (NIST Table 1)
    status: ground
    source: nist-munro-2000
    where: Table 1, Specific heat row, 20 degC column
  - benchmark: cte
    label: Mean coefficient of thermal expansion, TiB2 (NIST trend value)
    value: 7.4
    unit: 10-6/K
    scope: material
    conditions:
      temperature: 20 degC
      basis: mean linear CTE, alpha m = (2 alpha a + alpha c) / 3, from the single-crystal axial values; reference state 20 degC
    method: Thermal expansion alpha m row of NIST Table 1 (footnote h). The paper prints 10 to the power -6 per K.
    status: ground
    source: nist-munro-2000
    where: Table 1, Thermal expansion alpha m row, 20 degC column; footnote h
  - benchmark: cte
    label: Coefficient of thermal expansion, TiB2 (review table)
    value: 8.6
    unit: 10-6/K
    scope: material
    conditions:
      basis: TiB2 column of the review's property table; temperature not stated
    method: CTE row of Table 1 in the 2024 review, printed as 10-6 K-1
    status: ground
    source: lv-tib2-2024
    where: Table 1, CTE row, TiB2 column
  - benchmark: electrical_resistivity
    label: Electrical resistivity, TiB2 (review table)
    value: 9
    value_high: 15
    bound: range
    unit: uOhm·cm
    scope: material
    conditions:
      basis: TiB2 column of the review's property table; temperature not stated
    method: Printed as 9-15 with unit 10-6 Ohm·cm in Table 1 of the 2024 review; the same value in micro-ohm centimetres
    status: ground
    source: lv-tib2-2024
    where: Table 1, Electrical resistivity row, TiB2 column
  - benchmark: oxidation_resistance_temp
    label: Oxidation resistance limit, TiB2 (review table)
    value: 1200
    bound: upper
    unit: degC
    scope: material
    conditions:
      atmosphere: air (the review does not state the atmosphere)
      basis: TiB2 column of the review's property table, printed as less than 1200
    method: Oxidation resistance row of Table 1 in the 2024 review. Not a rate or a test result.
    status: ground
    note: Custom property name; no oxidation-limit name in the canon file. The review's text calls oxidation resistance inadequate.
    source: lv-tib2-2024
    where: Table 1, Oxidation resistance row, TiB2 column
  - benchmark: particle_size_d50
    label: Particle size D50, TiB2 powder grade D
    value: 3.5
    value_high: 6
    bound: range
    unit: micrometre
    scope: material
    conditions:
      grade: Grade D
      method_detail: laser diffraction, ASTM C 1070 (Microtrac)
    method: Particle size distribution table, D50 row, grade D column (datasheet dated 2007)
    status: ground
    note: Custom property name. Powder property, not a bulk property.
    source: hoganas-pd5123
    where: Particle Size Distribution table, D50 row, Grade D
corrosion:
  - environment: Oxidizing air at 800 to 1200 degC (cyclic oxidation of cold-pressed pellets)
    headline: TiO2 and B2O3 form; B2O3 volatilisation has a significant effect as the temperature rises.
    effect: Ozkan et al. oxidised cold-pressed TiB2 pellets at 800 to 1200 degC for 5, 10, 15 and 20 h. XRD found TiO2 and B2O3 as oxidation products. The authors say volatilisation of B2O3 had a significant effect on oxidation as the temperature increased, and that their samples oxidised faster than values in the literature because of their porosity. The abstract gives no rate constants.
    rating: moderate
    conditions:
      temperature: 800 to 1200 degC
      time: 5, 10, 15 and 20 h
      form: cold-pressed pellets, porous
    source: ozkan-2017
    where: Abstract (full text not read)
  - environment: Oxidizing air at 400 to 1000 degC (TiB2 films and coatings)
    headline: Films lose oxidation resistance above 400 degC; between 650 and 1000 degC the scale is laminated TiO2 and glassy B2O3.
    effect: Bahr et al. say the oxidation resistance of TiB2-based films is limited above 400 degC. Between 650 and 1000 degC the scale is a laminated structure of crystalline TiO2 and glassy, amorphous B2O3. This is a coatings study, so the numbers describe thin films, not bulk parts.
    rating: moderate
    conditions:
      form: TiB2-based films and coatings
      atmosphere: air (per the paper's oxidation studies)
    source: bahr-2023
    where: Introduction, paragraph on oxidation of TiB2 films
  - environment: Oxidation at high temperature, followed by room-temperature testing
    headline: Strength of specimens oxidised at higher temperatures is lower at room temperature, but B2O3 can heal cracks up to about 1000 degC.
    effect: NIST says crack healing by oxidation and formation of B2O3 may add to the strength rise with temperature up to about 1000 degC. Room-temperature strengths of specimens oxidised at higher temperatures appear to be diminished by oxidation.
    rating: moderate
    conditions:
      temperature: up to about 1000 degC for crack healing; above that for strength loss
      atmosphere: oxidizing
    source: nist-munro-2000
    where: Section 3.2 (Strength), paragraph on temperature dependence
risks:
  hazards:
    - text: 'PubChem aggregated GHS for titanium diboride (CID 92028754, signal word Warning): H302 harmful if swallowed, H312 harmful in contact with skin and H332 harmful if inhaled, each in 90.1 percent of the 218 company reports that gave hazard codes. 6.4 percent (15 of 233) of reports say it does not meet GHS hazard criteria.'
      ghs:
        - H302
        - H312
        - H332
      source: pubchem-tib2
      where: Safety and Hazards, GHS Classification
    - text: 'Supplier data (Hoganas grade D powder, 2007): the datasheet has no hazard section. No supplier safety data sheet with GHS classification was read in this run.'
      ghs: []
      source: hoganas-pd5123
      where: Datasheet, whole document (no hazard section)
  failure_risks:
    - mode: Brittle fracture of dense ceramic
      trigger: Tensile or bending load on a flaw
      consequence: 'NIST trend values at 20 degC: flexural strength 400 MPa, fracture toughness 6.2 MPa·m1/2 and Weibull modulus 11, so strength varies from part to part'
      severity: moderate
      source: nist-munro-2000
      where: Table 1 (flexural strength, fracture toughness, Weibull modulus); Section 3.2
    - mode: Strength loss after high-temperature oxidation
      trigger: Exposure to oxidizing air at high temperature
      consequence: NIST says room-temperature strengths of specimens oxidised at higher temperatures are diminished; the review says oxidation resistance is inadequate for wide use
      severity: moderate
      source: nist-munro-2000
      where: Section 3.2 (Strength), last paragraph before Table 1
  side_effects: []
  handling:
    - text: 'Powder: PubChem lists H302, H312 and H332 for the compound. Avoid swallowing it, skin contact and breathing the dust.'
      source: pubchem-tib2
      where: Safety and Hazards, GHS Classification
    - text: Grade D is a greyish powder with at least 30.0 percent boron by mass, at most 1.1 percent oxygen and at most 0.1 percent iron (Hoganas datasheet). Control dust when handling it.
      source: hoganas-pd5123
      where: Chemical Characteristics table and Description of Product
  mitigations: []
uses:
  - application: structures
    device: Armour, cutting tools and wear-resistant parts
    example: NIST lists TiB2 for impact-resistant armour, cutting tools, crucibles and wear-resistant coatings. The 2024 review lists high-temperature structural materials, cutting tools, armour, electrodes for metal smelting and wear-resistant parts.
    source: nist-munro-2000
    where: Section 1 (Introduction), first paragraph
  - application: mechanisms
    device: Wear-resistant parts and coatings
    example: The 2024 review names wear-resistant parts among TiB2 applications, and says TiB2 is a cathode material for salt-bath electrolysis in aluminium production.
    source: lv-tib2-2024
    where: Abstract and Introduction, first paragraph
supply:
  - subject: Titanium (sponge metal, the titanium half of TiB2)
    abundance: 'USGS: the United States produced no titanium sponge in 2025 and its last domestic plant closed in 2024. Imports of sponge were an estimated 44,000 tons in 2025.'
    producers:
      - country: China
        share_percent: 70.3
        year: 2025
      - country: Japan
        share_percent: 14.3
        year: 2025
      - country: Russia
        share_percent: 6.8
        year: 2025
      - country: Kazakhstan
        share_percent: 4.3
        year: 2025
      - country: Saudi Arabia
        share_percent: 3.2
        year: 2025
    critical_lists:
      - list: EU critical raw materials list (Regulation (EU) 2024/1252, Titanium metal)
        listed: true
    recycling: 'USGS: consumption data for titanium scrap are withheld. U.S. scrap imports were an estimated 32,000 tons in 2025. A Virginia company began making titanium powder from scrap in late 2024 and aimed for 1,400 tons per year in 2027.'
    substitutes:
      - 'USGS: aluminum, nickel, specialty steels and zirconium alloys may be substituted for titanium where corrosion resistance is needed (metal applications, not TiB2 specifically).'
    source: usgs-mcs2026-titanium
    where: 'World Sponge Metal Production table, 2025 column (shares calculated by Space Mushroom: country sponge output over the 370,000 t world total as printed; the printed countries sum to 366,300 t); Domestic Production and Use; Events, Trends, and Issues; Recycling; Substitutes'
  - subject: Boron (the boron half of TiB2)
    abundance: 'USGS: borates occur in volcanic and arid deposits. The 2025 world production total is withheld (XX), so shares are not calculated. 2025 production as printed: Turkey 1,500, Bolivia 380, Chile 300, China 230 (boric oxide equivalent), Peru 220, Argentina 170, Russia 80, Germany 40. U.S. imports of all forms came from Turkey (90 percent, 2021 to 2024).'
    producers: []
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (boron added in the final 2025 list, per the boron chapter)
        listed: true
      - list: EU critical raw materials list (Boron/Borate)
        listed: true
    recycling: 'USGS: insignificant.'
    substitutes:
      - 'USGS: substitution is possible in detergents, enamels, insulation and soaps. No substitute for boron in TiB2 is discussed.'
    source: usgs-mcs2026-boron
    where: World Production and Reserves table, 2025 column (world total XX); Import Sources (2021 to 2024); Critical lists paragraph in Events, Trends and Issues; Recycling; Substitutes
media: []
documents:
  - title: NIST J. Res. 105(5), Munro, Material Properties of Titanium Diboride (2000)
    type: paper
    url: https://nvlpubs.nist.gov/nistpubs/jres/105/5/j55mun.pdf
    year: 2000
  - title: Lv et al. 2024, Review on the Development of Titanium Diboride Ceramics, Recent Progress in Materials 6(2) (open access)
    type: paper
    url: https://lidsen.com/journals/rpm/rpm-06-02-009
    year: 2024
  - title: USGS Mineral Commodity Summaries 2026, Titanium and Titanium Dioxide
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-titanium.pdf
    year: 2026
  - title: USGS Mineral Commodity Summaries 2026, Boron
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-boron.pdf
    year: 2026
  - title: PubChem compound record CID 92028754, Titanium diboride (GHS classification)
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/92028754
    year: 2026
  - title: Hoganas datasheet PD-5123, Titanium Diboride Grades D, SE and F
    type: datasheet
    url: https://www.hoganas.com/globalassets/downloads/stc/PD-5123.pdf
    year: 2007
  - title: Ozkan, Dokumaci and Onay 2017, Cyclic oxidation behavior of TiB2 pellets at elevated temperatures (abstract read)
    type: paper
    url: https://aperta.ulakbim.gov.tr/records/111472
    year: 2017
  - title: Bahr et al. 2023, Quaternary diborides, Materials Research Letters 11(9) (TU Wien repository copy)
    type: paper
    url: https://doi.org/10.1080/21663831.2023.2225554
    year: 2023
gaps:
  - 'Titanium on the USGS 2025 List of Critical Minerals: the USGS list page returned HTTP 403 and the titanium chapter read does not state its status. Only the EU list is recorded.'
  - 'Boron producer shares are not calculated: the 2025 world total is withheld (XX) in the USGS boron chapter. Country tonnages are in the abundance text only.'
  - Titanium sponge shares are calculated against the 370,000 t world total as printed; the printed country values sum to 366,300 t.
  - 'Molten aluminium and cathode corrosion of TiB2: no source read. The cathode use is described, but no corrosion or life data were found.'
  - 'Space use: no NASA, ESA or flight source for TiB2 was found. The NASA search returned ZrB2 and HfB2 ultra-high-temperature ceramics for sharp leading edges, which are other grades and were not used.'
  - 'Vacuum, radiation, thermal-vacuum and atomic-oxygen behaviour of TiB2: not read.'
  - 'Oxidation rates for bulk TiB2 in air: not found in a source read. Ozkan et al. is read as an abstract only; Bahr et al. covers thin films.'
  - 'Manufacturer datasheet with density, thermal conductivity and resistivity: the 3M TiB2 powder datasheet link returned an error page, and the Goodfellow and Cersol listings are distributor pages, so they were not used.'
  - Molar mass 69.489 g/mol and the hexagonal lattice constants (a 302.36 pm, c 322.04 pm) are on Wikipedia; they are not used as profile values, and the recipe uses only the NIST and Hoganas composition.
  - Sources disagree on flexural strength (400 MPa NIST against 700 to 1000 MPa review), fracture toughness (6.2 against 4 to 5 MPa·m1/2), hardness at 20 degC (25 GPa NIST, Vickers 5 N, against 25 to 35 GPa review) and thermal conductivity (96 W/m·K NIST against 60 to 120 review). All are kept, with the source named.
  - 'Designations (UNS, EN, DIN, JIS, AISI and similar codes) for TiB2: none printed in a source read in this run.'
  - 'Custom property names used because they are not in spores/property-canon.yaml: hardness, fracture_toughness, weibull_modulus, oxidation_resistance_temp, particle_size_d50.'
  - 'Compare paragraph: the review''s comparison table has no readable column headings after text extraction, so the materials it compares TiB2 with are not named in this profile.'
sources:
  nist-munro-2000:
    title: Munro, R. G., Material Properties of Titanium Diboride, J. Res. Natl. Inst. Stand. Technol. 105, 709-720 (2000)
    url: https://nvlpubs.nist.gov/nistpubs/jres/105/5/j55mun.pdf
    kind: paper
    license: public domain (NIST)
  lv-tib2-2024:
    title: Lv X, Yin Z, Yang Z, Chen J et al., Review on the Development of Titanium Diboride Ceramics, Recent Progress in Materials 6(2), doi 10.21926/rpm.2402009
    url: https://lidsen.com/journals/rpm/rpm-06-02-009
    kind: paper
    license: open access, CC BY (per the journal)
  usgs-mcs2026-titanium:
    title: USGS Mineral Commodity Summaries 2026, Titanium and Titanium Dioxide
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-titanium.pdf
    kind: report
    license: US government work, public domain
  usgs-mcs2026-boron:
    title: USGS Mineral Commodity Summaries 2026, Boron
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-boron.pdf
    kind: report
    license: US government work, public domain
  pubchem-tib2:
    title: PubChem compound CID 92028754, Titanium diboride (GHS classification, aggregated notifications; CAS 12045-63-5)
    url: https://pubchem.ncbi.nlm.nih.gov/compound/92028754
    kind: database
    license: PubChem public database
  hoganas-pd5123:
    title: Hoganas, Titanium Diboride Grades D, SE and F, datasheet PD-5123 (issue 5-31.07.2007)
    url: https://www.hoganas.com/globalassets/downloads/stc/PD-5123.pdf
    kind: datasheet
    license: vendor datasheet, cited not reproduced
  ozkan-2017:
    title: Ozkan I, Dokumaci E, Onay A. B., Cyclic oxidation behavior of TiB2 pellets at elevated temperatures (2017)
    url: https://aperta.ulakbim.gov.tr/records/111472
    kind: paper
    license: repository record (abstract read)
  bahr-2023:
    title: Bahr A. et al., Quaternary diborides, improving the oxidation resistance of TiB2 coatings by disilicide alloying, Materials Research Letters 11(9), 733-741 (2023)
    url: https://doi.org/10.1080/21663831.2023.2225554
    kind: paper
    license: author version in TU Wien repository
  ec-crm:
    title: European Commission, Critical raw materials (list under Regulation (EU) 2024/1252)
    url: https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en
    kind: web
    license: European Commission web page
  wikipedia-tib2:
    title: Wikipedia, Titanium diboride (molar mass, structure and history only)
    url: https://en.wikipedia.org/wiki/Titanium_diboride
    kind: web
    license: CC BY-SA
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 27
  unreachable: 2
  caveats: 4
  note: 'Written in this run from NIST Munro 2000 (Table 1 trend values), the 2024 open-access review (Table 1), PubChem GHS, USGS 2026 titanium and boron chapters, the Hoganas datasheet and two oxidation papers. The USGS critical-list page and the 3M datasheet were not readable. verify-values: 27 of 27 values found in their cited sources.'
story:
  recipe:
    line: 'TiB2 has one titanium atom and two boron atoms per formula unit, in a hexagonal layered structure (space group P6/mmm, NIST). Hoganas sells the powder as grades D, SE and F; grade D has at least 30.0 percent boron by mass and at most 1.1 percent oxygen. The review says pure TiB2 sinters poorly: near-theoretical density needs pressureless sintering above 2000 degC or sintering additives at lower temperature.'
    parts:
      - name: Titanium
        symbol: Ti
        role: Metal atom in the hexagonal structure. Titanium and boron together give TiB2 its hardness and electrical conductivity.
      - name: Boron
        symbol: B
        share: at least 30.0 percent by mass (Hoganas grade D)
        role: Forms boron layers within the crystal. Boron is also the element that oxidises to B2O3 in air, which affects the oxidation behaviour.
  risk_groups:
    - title: For people
      level: 0
      verdict: Harmful if swallowed, in skin contact or inhaled (PubChem)
      lead: Aggregated company notifications give three harmful-category hazard statements for titanium diboride, but 6.4 percent of reports say it does not meet GHS criteria. Treat the powder as harmful and control dust.
      points:
        - label: Dust
          line: Grade D is a greyish powder with a D50 of 3.5 to 6 micrometres (Hoganas). Control dust. The datasheet has no hazard section.
        - label: Ingestion and skin
          line: PubChem's H302 (harmful if swallowed) and H312 (harmful in contact with skin) appear in 90.1 percent of the reports that gave hazard codes.
    - title: If a part fails
      lead: These numbers are NIST trend values for dense material at 20 degC.
      points:
        - label: Brittleness
          line: Flexural strength of 400 MPa, fracture toughness of 6.2 MPa·m1/2 and a Weibull modulus of 11. The strength of one part can differ from another.
        - label: Oxidation
          line: Specimens oxidised at high temperature are weaker at room temperature, according to NIST.
  why: Titanium diboride is a hard, stiff ceramic that also conducts electricity. At 20 degC NIST gives an elastic modulus of 565 GPa and a Vickers hardness of about 25 GPa for dense material. The review gives a melting point of 3225 degC. Those properties explain its use in armour, cutting tools and wear parts. Its oxidation resistance and sinterability are the main limits, which the review and the oxidation papers describe.
  uses:
    - where: Armour, cutting tools and wear parts
      line: NIST lists impact-resistant armour, cutting tools, crucibles and wear-resistant coatings. The 2024 review lists the same uses, plus high-temperature structural materials and electrodes for metal smelting.
    - where: Aluminium production cathodes
      line: NIST describes TiB2 cathodes for the electrochemical reduction of alumina to aluminium. The review calls it a cathode material for salt-bath electrolysis in aluminium production.
    - where: Space applications
      line: No flight, space or lunar source for TiB2 was read in this run.
  can_do:
    - label: Stiffness
      benchmark: elastic_modulus
      line: Dense TiB2 has an elastic modulus of 565 GPa at 20 degC (NIST trend value, about 5 percent uncertainty). The review gives 500 to 560 GPa.
    - label: Hardness
      benchmark: hardness
      line: Vickers hardness is about 25 GPa at 20 degC at a 5 N load (NIST). It falls to 11 GPa at 500 degC and 4.6 GPa at 1000 degC. The review gives 25 to 35 GPa.
    - label: Melting
      benchmark: melting_point
      value: 3225 degC
      line: The review gives a melting point of 3225 degC for TiB2.
    - label: Heat conduction
      benchmark: thermal_conductivity
      value: 96 W/m·K
      line: NIST gives 96 W/m·K at 20 degC, falling to 78.1 W/m·K at 1000 degC. The review gives 60 to 120 W/m·K.
  compare: The review's property table sets TiB2 beside other high-temperature ceramics, but its column headings did not survive text extraction, so the materials it compares TiB2 with are not named here. Within this profile, TiB2 has a density of 4.5 g/cm3, a hardness of 25 to 35 GPa and a melting point of 3225 degC, with an oxidation resistance limit below 1200 degC.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Hardness
      benchmark: hardness
    - label: Thermal conductivity
      benchmark: thermal_conductivity
  handling:
    - 'Powder: PubChem lists H302, H312 and H332 for the compound. Avoid swallowing it, skin contact and breathing the dust.'
    - 'Oxidation: in air the surface forms TiO2 and B2O3. B2O3 volatilises as the temperature rises (Ozkan 2017, 800 to 1200 degC).'
    - Strength after high-temperature oxidation is lower at room temperature (NIST).
  good_for:
    - Hard, stiff parts. NIST gives a Vickers hardness of about 25 GPa and an elastic modulus of 565 GPa at 20 degC.
    - Electrically conductive hard parts. The review gives an electrical resistivity of 9 to 15 micro-ohm·cm.
  watch_out:
    - 'Brittleness: flexural strength of 400 MPa and a Weibull modulus of 11 at 20 degC (NIST).'
    - 'Oxidation: the review gives an oxidation resistance below 1200 degC and calls it inadequate for wide use. Thin films lose oxidation resistance above 400 degC (Bahr 2023).'
    - The sources disagree on flexural strength (400 MPa NIST against 700 to 1000 MPa review) and on thermal conductivity (96 W/m·K against 60 to 120 W/m·K).
    - No space, radiation or molten-aluminium corrosion data were read.
  verdict: Titanium diboride is a hard, stiff, electrically conductive ceramic with a melting point of 3225 degC. Its limits are oxidation in air at high temperature and brittleness. The sourced uses are terrestrial (armour, cutting tools, wear parts and cathodes), and no space application was found.