spore: profile id: pyrolytic-boron-nitride spore_version: 0.2 family: carbide-nitride-boride-ceramics name: Pyrolytic boron nitride (pBN) abbreviation: pBN role: crucible, container and insulator ceramic made by chemical vapour deposition category: ceramics type: nitrides summary: Pyrolytic boron nitride (pBN) is a dense form of boron nitride deposited from gas by chemical vapour deposition (CVD). Stanford Advanced Materials prints a bulk density of 2.0 to 2.19 g/cm3 and a maximum working temperature of 2200 °C for its pBN crucible (catalog PBN0922). The NASA oxidation study measured 2.12 to 2.19 g/cm3 for high-density CVD BN, and the supplier sheet, tube and crucible data disagree on strength. best_for: Crucibles, boats and insulating parts for high-temperature semiconductor and vacuum equipment, where a dense, high-purity BN form is needed weakest_at: Strength depends on the datasheet and on direction, and oxidation in air at high temperature degrades the material (NASA, Moore 1992) identity: formula: BN, boron nitride as a CVD deposit of layered, c-axis oriented plates cas: 10043-11-5 source: jacobson-oxidation where: Thermochemical considerations (BN reaction equation) and Starting Materials (pyrolytic BN from BCl3 and NH3); CAS number from the composition table of the hexagonal BN powder SDS (sam-hbn-sds) designations: - system: Trade name code: PBN0922 note: Stanford Advanced Materials catalog number for a pyrolytic boron nitride crucible source: sam-pbn-0922 where: Header, Catalog No. - system: Trade name code: PBN0923 note: Stanford Advanced Materials catalog number for pyrolytic boron nitride tubes source: sam-pbn-0923 where: Header, Catalog No. - system: Trade name code: PBN1343 note: Stanford Advanced Materials catalog number for a pyrolytic boron nitride sheet source: sam-pbn-sheet where: Product name line of the sheet page tags: environments: [] stresses: - extreme-heat applications: [] properties: - benchmark: density label: Bulk density, pBN crucible grade value: 2 value_high: 2.19 bound: range unit: g/cm3 scope: material conditions: form: pyrolytic BN crucible, catalog PBN0922 unit_in_source: g/cm3 note: datasheet does not say whether the figure is measured or theoretical method: Bulk density printed as 2.0-2.19g/cm3 in the supplier technical data sheet status: ground source: sam-pbn-0922 where: Properties table, row Bulk Density - benchmark: density label: Density, high-density CVD BN (measured) value: 2.12 value_high: 2.19 bound: range unit: g/cm3 scope: material conditions: form: high-density CVD BN plate, pyrolytic BN from BCl3 and NH3 unit_in_source: gm/cc basis: measured densities of each BN type studied (Table I caption) method: Measured density printed as 2.12-2.19 in Table I of the NASA oxidation study; the table header row is garbled in the copy read status: ground source: jacobson-oxidation where: Table I, row High density CVD BN - benchmark: density label: Density, low-density CVD BN (measured) value: 1.76 unit: g/cm3 scope: material conditions: form: low-density CVD BN plate unit_in_source: gm/cc basis: measured densities of each BN type studied (Table I caption) method: Measured density printed in Table I of the NASA oxidation study status: ground source: jacobson-oxidation where: Table I, row Low density CVD BN - benchmark: density label: Theoretical density of BN, as printed in the NASA study value: 2.27 unit: g/cm3 scope: material conditions: basis: theoretical value printed in Table I; not a measured value unit_in_source: gm/cc method: Row labelled Theoretical in Table I of the NASA oxidation study status: calculated source: jacobson-oxidation where: Table I, row Theoretical - benchmark: flexural_strength label: Flexural strength, pBN crucible grade value: 243.63 unit: MPa scope: material conditions: form: pyrolytic BN crucible, catalog PBN0922 temperature: not stated direction: not stated unit_in_source: Mpa method: Value printed in the Flexural Strength (Mpa) row of the supplier technical data sheet status: ground source: sam-pbn-0922 where: Properties table, row Flexural Strength (Mpa) - benchmark: flexural_strength label: Bending strength, pBN sheet grade (theoretical) value: 197 value_high: 244 bound: range unit: MPa scope: material conditions: form: pyrolytic BN sheet, catalog PBN1343 unit_in_source: N/mm2 basis: the page states that its values are based on theoretical values method: Bending Strength printed as 197-244 N/mm2 on the supplier sheet page, under a note that the values are theoretical status: calculated source: sam-pbn-sheet where: Specification table, row Bending Strength - benchmark: ultimate_tensile_strength label: Tensile strength, pBN tube grade, parallel direction value: 153.86 unit: MPa scope: material conditions: form: pyrolytic BN tube, catalog PBN0923 direction: parallel (direction as printed; not defined on the datasheet) unit_in_source: N/mm2 method: Value printed as 153.86 (parallel) in the Tensile Strength row of the supplier technical data sheet status: ground source: sam-pbn-0923 where: Properties table, row Tensile Strength (N/mm2) - benchmark: ultimate_tensile_strength label: Tensile strength, pBN sheet grade (theoretical) value: 80 unit: MPa scope: material conditions: form: pyrolytic BN sheet, catalog PBN1343 unit_in_source: N/mm2 basis: the page states that its values are based on theoretical values method: Tensile Strength printed as 80 N/mm2 on the supplier sheet page; it disagrees with the tube data sheet value above status: calculated source: sam-pbn-sheet where: Specification table, row Tensile Strength - benchmark: elastic_modulus label: Elastic modulus, pBN sheet grade (theoretical) value: 18 unit: GPa scope: material conditions: form: pyrolytic BN sheet, catalog PBN1343 basis: the page states that its values are based on theoretical values method: Elastic Modulus printed as 18 GPa on the supplier sheet page status: calculated source: sam-pbn-sheet where: Specification table, row Elastic Modulus - benchmark: thermal_conductivity label: Thermal conductivity, pBN crucible grade value: 43 value_high: 60 bound: range unit: W/(m·K) scope: material conditions: form: pyrolytic BN crucible, catalog PBN0922 direction: not stated temperature: not stated unit_in_source: W/M·k method: Range printed as 43-60 in the Thermal Conductivity row of the supplier technical data sheet status: ground source: sam-pbn-0922 where: Properties table, row Thermal Conductivity (W/M·k) - benchmark: dielectric_strength label: Dielectric strength at room temperature, pBN tube grade value: 56 unit: kV/mm scope: material conditions: form: pyrolytic BN tube, catalog PBN0923 temperature: room temperature (RT, as printed) unit_in_source: KV/mm method: Value printed in the Dielectric Strength (RT) row of the supplier technical data sheet status: ground source: sam-pbn-0923 where: Properties table, row Dielectric Strength (RT) (KV/mm) - benchmark: dielectric_strength label: Dielectric strength at room temperature, pBN sheet grade (theoretical) value: 56 unit: kV/mm scope: material conditions: form: pyrolytic BN sheet, catalog PBN1343 temperature: room temperature (RT, as printed) basis: the page states that its values are based on theoretical values method: Dielectric Strength (RT) printed as 56 KV/mm on the supplier sheet page status: calculated source: sam-pbn-sheet where: Specification table, row Dielectric Strength (RT) - benchmark: max_service_temp label: Maximum working temperature, pBN crucible grade value: 2200 unit: °C scope: material conditions: form: pyrolytic BN crucible, catalog PBN0922 atmosphere: not stated unit_in_source: ℃ method: Max. Working Temperature printed as 2200℃ in the supplier technical data sheet status: ground source: sam-pbn-0922 where: Properties table, row Max. Working Temperature - benchmark: max_service_temp label: Maximum working temperature, pBN tube grade value: 2400 unit: °C scope: material conditions: form: pyrolytic BN tube, catalog PBN0923 atmosphere: not stated unit_in_source: ℃ method: Max. Working Temperature printed as 2400℃ in the supplier technical data sheet status: ground source: sam-pbn-0923 where: Properties table, row Max. Working Temperature - benchmark: max_service_temp label: Maximum operating temperature, pBN sheet grade (theoretical) value: 1700 unit: °C scope: material conditions: form: pyrolytic BN sheet, catalog PBN1343 atmosphere: not stated basis: the page states that its values are based on theoretical values unit_in_source: ℃ method: Max. Operating Temp. printed as 1700 ℃ in the supplier sheet specification table, under the theoretical-values note status: calculated source: sam-pbn-sheet where: Specification table, row Max. Operating Temp. - benchmark: purity label: Purity, pBN crucible grade value: 99.9 unit: '%' scope: material conditions: form: pyrolytic BN crucible, catalog PBN0922 method: Purity printed as 99.9% in the supplier technical data sheet header status: ground source: sam-pbn-0922 where: Header table, row Purity - benchmark: deposition_temperature label: CVD deposition temperature range, pyrolytic BN value: 1400 value_high: 1900 bound: range unit: °C scope: material conditions: process: CVD of pyrolytic BN from BCl3 and NH3 note: the lower limit is printed with OCR garbling in the copy read; 1400°C also appears in another line of the same paper method: Deposition temperatures printed as about 1900°C down to about 1400°C in the Starting Materials section of the NASA oxidation study status: ground source: jacobson-oxidation where: Starting Materials, first paragraph - benchmark: deposition_temperature label: CVD coating temperature, PBN on Nicalon yarn value: 1080 unit: °C scope: material conditions: process: PBN coating from BCl3 and ammonia on Nicalon NL 202 yarn note: most coatings made at this temperature to limit thermal damage to the yarn method: Printed as around 1080°C in the Introduction section of the NASA final report (thin coating on fibre, not bulk pBN) status: ground source: moore1992 where: Introduction, first paragraph; Section on batch coating corrosion: - environment: Air at high temperature, thin PBN coating on Nicalon fibre headline: Good oxidation resistance in air up to 800°C for a thin PBN coating; properties degrade after air oxidation at 1000°C. effect: The source says the PBN-coated Nicalon “showed good resistance to oxidation in air up to 800°C, but the properties were degraded after air oxidation at 1000°C.” The coatings were 0.1 to 0.7 microns thick, and the tests were on coated yarn, not on bulk pBN. rating: moderate conditions: form: PBN coating 0.1-0.7 microns on Nicalon NL 202 yarn test: air oxidation at the stated temperatures source: moore1992 where: Abstract and oxidation paragraphs - environment: Oxygen at high temperature, dense and low-density CVD BN (thermogravimetric tests) headline: Dense, well-ordered CVD BN oxidizes slowly; lower-density CVD BN oxidizes much faster. effect: The primary reaction is written as 2 BN(s) + 3/2 O2(g) = B2O3(l) + N2(g). The paper says the high-density CVD BN “oxidizes slowly, according to a parabolic rate law,” and that “Lower density CVD BN showed rapid linear growth rates.” rating: moderate conditions: atmosphere: '100% oxygen, thermogravimetric tests (rate constants not recorded: printed with exponents)' source: jacobson-oxidation where: Thermochemical Considerations; Conclusions; Table II - environment: Trace water vapour in the oxygen stream headline: Trace water vapour makes oxidation of dense CVD BN paralinear. effect: The paper states that “The ~20 ppm of water vapor present in the gas stream created volatile HxByOz(g) species simultaneous with the oxidation process and led to paralinear behavior.” rating: moderate conditions: water_vapour: about 20 ppm, as printed source: jacobson-oxidation where: Conclusions risks: hazards: - text: Momentive describes pyrolytic BN as “Nonhazardous” on its product page. No pBN-specific safety data sheet was found in this run. ghs: [] source: momentive-pbn where: Product page, safety statement - text: A supplier safety data sheet for hexagonal boron nitride powder (a different form from pBN) says it is “Not a hazardous substance or mixture.” The same sheet states that the toxicological properties have not been thoroughly investigated. ghs: [] source: sam-hbn-sds where: Sections 2.1 and 2.2; Section 11, final paragraph failure_risks: - mode: Strength loss after air oxidation trigger: Heating in air at 1000°C (thin PBN coating on Nicalon yarn) consequence: The source says “most of a 0.1-0.2 micron thick coating can be converted into boric oxide after a 30-minute heat treatment in air at 1000°C,” and the coated yarn's properties were degraded after air oxidation at 1000°C. severity: moderate source: moore1992 where: Abstract; oxidation paragraph - mode: Fast oxidation of low-density CVD BN trigger: Heating in oxygen at high temperature consequence: The NASA study reports rapid linear growth for lower-density CVD BN, which is recorded here at 1.76 g/cm3 (Table I). severity: moderate source: jacobson-oxidation where: Conclusions; Table I side_effects: - text: Oxidation releases nitrogen, and the paper notes that “N2(g) may also further oxidize to NOx(g).” affects: Off-gas from a hot zone that contains air or oxygen source: jacobson-oxidation where: Thermochemical Considerations handling: - text: Momentive says pBN can be deposited and then machined into 2D or 3D shapes. source: momentive-pbn where: Product page, manufacturing paragraph - text: Machining makes dust. The hexagonal BN powder SDS advises a particulate mask only where nuisance dust is a concern. source: sam-hbn-sds where: Section 8, respiratory protection mitigations: [] uses: - application: electronics-and-chips device: Crucibles and containers for compound-semiconductor crystal growth and for MBE and MOCVD equipment example: Stanford Advanced Materials lists PBN sheets as crucibles or containers in crystal growth processes. Momentive lists crystal growth of GaAs and InP and MBE and MOCVD equipment among pBN applications. source: sam-pbn-sheet where: Applications section, Crystal Growth Processes - application: electronics-and-chips device: Insulating and heat-spreading parts for LEDs and laser diodes example: Stanford Advanced Materials says PBN sheets provide insulation and heat dissipation for high-performance semiconductor devices, including LEDs and laser diodes. source: sam-pbn-sheet where: Applications section, Electronic Packaging - application: electronics-and-chips device: Insulating parts in microwave and RF amplifiers example: Stanford Advanced Materials says PBN's high thermal conductivity and dielectric properties make it suitable for microwave and RF amplifier applications. source: sam-pbn-sheet where: Applications section, Microwave and RF Amplifiers - application: electronics-and-chips device: Helix support rods for traveling wave tubes example: Momentive lists helix support rods for traveling wave tube (TWT) applications among its pBN shapes. source: momentive-pbn where: Product page, applications list supply: - subject: Boron abundance: 'Production by country as printed in USGS MCS 2026, thousand metric tons, 2025: Turkey 1,500 (refined borates); Bolivia 380 (ulexite); Peru 220 (crude borates); Chile 300 (ulexite); China 230 (boric oxide equivalent); Argentina 170 (crude ore); Russia 80 (datolite ore); Germany 40 (compounds). The U.S. figure is withheld, and no world total is published (shares not calculated).' producers: - country: Turkey year: 2025 - country: Bolivia year: 2025 - country: Peru year: 2025 - country: Chile year: 2025 - country: China year: 2025 - country: Argentina year: 2025 - country: Russia year: 2025 - country: Germany year: 2025 critical_lists: - list: USGS 2025 Final List of Critical Minerals (boron added, as stated in USGS MCS 2026) listed: true recycling: 'USGS: boron recycling is insignificant (Recycling, Boron chapter).' substitutes: - 'USGS: substitution for boron is possible in detergents, enamels, insulation and soaps; no substitute is discussed for pyrolytic BN.' source: usgs-mcs2026-boron where: Domestic Production and Use; World Production and Reserves table (2025 column); critical list paragraph; Recycling; Substitutes media: [] documents: - title: 'Stanford Advanced Materials technical data sheet: Pyrolytic Boron Nitride Crucible, catalog PBN0922' type: datasheet url: https://samaterials.com/tds/sc/1730356020-PBN0922.pdf - title: 'Stanford Advanced Materials technical data sheet: Pyrolytic Boron Nitride Tubes, catalog PBN0923' type: datasheet url: https://samaterials.com/tds/sc/1730356023-PBN0923.pdf - title: 'Stanford Advanced Materials: PBN Sheet (PBN1343) product page' type: datasheet url: https://www.samaterials.com/boron-nitride/1343-pyrolytic-boron-nitride-sheet-pbn-sheet.html - title: 'NASA: High Temperature Oxidation of Boron Nitride, Part I, Monolithic Boron Nitride (Jacobson, Farmer, Moore, Sayir)' type: report url: https://ntrs.nasa.gov/citations/20010064405 - title: 'NASA contract report: Pyrolytic Boron Nitride Coatings on Ceramic Yarns and Fabrication of Insulations (Moore, 1992)' type: report url: https://ntrs.nasa.gov/citations/19920006927 year: 1992 - title: 'USGS Mineral Commodity Summaries 2026: Boron' type: report url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-boron.pdf year: 2026 - title: 'Safety data sheet: Boron nitride (hexagonal BN powder), Stanford Advanced Materials' type: sds url: https://samaterials.com/tds/1712564705-hbn0921-sds.pdf gaps: - No space-flight, vacuum, radiation or space-environment result for pBN was found in any source read in this run, so tags.environments and tags.applications are empty. - No pBN-specific safety data sheet was found. PubChem (CID 66227) could not be read in this run, so the hazard entries rest on the Momentive statement and an SDS for hexagonal BN powder. - The sheet page prints in-plane and through-plane thermal conductivity values with no unit, so they are not recorded. - Volume resistivity is printed with an exponent that the copy read flattened (PBN0922 and PBN0923), so it is not recorded. - The sheet page prints lattice constants and the CTE with exponents, so they are not recorded. - 'Momentive''s typical values (density, thermal conductivity, impurity level, strengths, dielectric strength) could not be checked: the page blocks automated access, so none of its numbers are recorded as properties.' - The NASA oxidation kinetics table is printed with exponents, so the rate constants are not recorded. - The NASA Table I row label for density is garbled in the copy read; the table caption gives the unit. - The supplier sheet, tube and crucible data disagree on strength and maximum temperature; both values are kept with their conditions. - The EU critical raw materials list was not checked for boron, and no supply source was read for boron trichloride or ammonia. - The USGS 2025 producer table has no world total, so producer shares are not calculated; tonnage is given as printed in the supply text. - Atomic weights were not read in this run, so the recipe gives atom counts only. - Purity and deposition_temperature are short names that are not in the canonical benchmark list. - Hot-pressed BN values in the boron-nitride profile describe a different form and are not used here. license: CC-BY-4.0 updated: '2026-11-01' review: status: draft method: assistant checked_values: 18 unreachable: 0 caveats: 6 note: Read by an AI assistant on 2026-11-01. Values come from supplier datasheets, a NASA oxidation study and a NASA contract report read in this run. Six values are labelled theoretical by the supplier or the study, and are marked calculated. sources: sam-pbn-0922: title: 'Stanford Advanced Materials technical data sheet: Pyrolytic Boron Nitride Crucible (catalog PBN0922)' id: catalog PBN0922 url: https://samaterials.com/tds/sc/1730356020-PBN0922.pdf kind: datasheet license: supplier document, cited not reproduced sam-pbn-0923: title: 'Stanford Advanced Materials technical data sheet: Pyrolytic Boron Nitride Tubes (catalog PBN0923)' id: catalog PBN0923 url: https://samaterials.com/tds/sc/1730356023-PBN0923.pdf kind: datasheet license: supplier document, cited not reproduced sam-pbn-sheet: title: 'Stanford Advanced Materials: Pyrolytic Boron Nitride Sheet (PBN Sheet), catalog PBN1343, specification table' id: catalog PBN1343 url: https://www.samaterials.com/boron-nitride/1343-pyrolytic-boron-nitride-sheet-pbn-sheet.html kind: datasheet license: supplier web page, cited not reproduced jacobson-oxidation: title: 'High Temperature Oxidation of Boron Nitride, Part I: Monolithic Boron Nitride (Jacobson, Farmer, Moore, Sayir; NASA Lewis Research Center)' id: NASA NTRS 20010064405 (paper year not printed in the copy read) url: https://ntrs.nasa.gov/citations/20010064405 kind: report license: public domain (NASA) moore1992: title: Pyrolytic Boron Nitride Coatings on Ceramic Yarns and Fabrication of Insulations, final report, contract NAS2-13109 (Moore, Union Carbide Coatings Service Corporation) id: NASA NTRS 19920006927; final report dated January 28, 1992 url: https://ntrs.nasa.gov/citations/19920006927 year: 1992 kind: report license: public domain (NASA) usgs-mcs2026-boron: title: Mineral Commodity Summaries 2026, Boron id: USGS MCS 2026, February 2026 url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-boron.pdf year: 2026 kind: report license: public domain (USGS) sam-hbn-sds: title: 'Safety data sheet: Boron nitride (hexagonal BN powder), Stanford Advanced Materials' id: Stanford Advanced Materials SDS, hexagonal BN powder (not pyrolytic BN) url: https://samaterials.com/tds/1712564705-hbn0921-sds.pdf kind: datasheet license: supplier document, cited not reproduced momentive-pbn: title: Pyrolytic Boron Nitride (pBN) Coatings and Shapes, Momentive Technologies product page id: Momentive product page, pBN coatings and shapes url: https://www.momentivetech.com/products/ceramics/ceramic-coatings/pyrolytic-boron-nitride-pbn-coating-and-shapes kind: web license: supplier web page, cited not reproduced story: recipe: line: Pyrolytic boron nitride is one boron atom bonded to one nitrogen atom per formula unit (BN), built up as a layered film. Jacobson et al. describe it as made by reacting boron trichloride (BCl3) with ammonia (NH3) at high temperature, with the layers aligned along the c-axis, which is the stacking direction of the hexagonal planes. parts: - name: Boron symbol: B role: Supplied from boron trichloride in the gas phase. Forms the boron atom in each BN unit. source: jacobson-oxidation where: Starting Materials - name: Nitrogen symbol: 'N' role: Supplied from ammonia. Forms the nitrogen atom in each BN unit; during oxidation it leaves as N2. source: jacobson-oxidation where: Starting Materials; Thermochemical Considerations risk_groups: - title: For people level: 0 verdict: Not hazardous per Momentive; no pBN SDS found lead: Momentive calls pBN nonhazardous, and the SDS for hexagonal BN powder gives no hazard classification. No pBN-specific safety data sheet was found, and the toxicology of the material is not well documented. points: - label: The material line: Momentive describes pyrolytic BN as nonhazardous. A supplier SDS for hexagonal BN powder (a different form) states that it is not a hazardous substance or mixture. - label: Toxicology line: The same hexagonal BN SDS states that its toxicological properties have not been thoroughly investigated. - label: Dust line: Machining makes dust. The hexagonal BN SDS advises a particulate mask only where nuisance dust is a concern. - title: If it oxidizes in air level: 1 verdict: Slow oxidation in air at high temperature lead: The oxidation tests in these sources were run in air or oxygen at high temperature. They are laboratory results, not field incidents. points: - label: Products line: The NASA study writes the primary reaction as BN plus oxygen giving boron oxide (B2O3) and nitrogen (N2). The paper notes that N2 may further oxidize to NOx. - label: Dense material line: The NASA study describes high-density CVD BN as oxidizing slowly, according to a parabolic rate law. - label: Thin coating line: For a thin PBN coating on fibre, the Moore report found good resistance to oxidation in air up to 800°C, and property loss after air oxidation at 1000°C. why: 'Pyrolytic boron nitride (pBN) is boron nitride deposited from gas by chemical vapour deposition. Supplier datasheets for the pBN crucible and tube grades print a bulk density of 2.0 to 2.19 g/cm3, and the NASA oxidation study measured 2.12 to 2.19 g/cm3 for high-density CVD BN. The grades differ in rated temperature: the sheet page lists 1700 °C as a theoretical value, while the crucible and tube data sheets print 2200 °C and 2400 °C. Buyers should check the grade they order, because the sources do not agree.' uses: - where: Crystal growth and MBE equipment line: Stanford Advanced Materials lists PBN as crucibles or containers in crystal growth processes. Momentive lists crystal growth of GaAs and InP and MBE and MOCVD equipment among pBN applications. - where: LEDs and laser diodes line: Stanford Advanced Materials says PBN sheets provide insulation and heat dissipation for high-performance semiconductor devices, including LEDs and laser diodes. - where: Microwave and RF amplifiers line: Stanford Advanced Materials says PBN's high thermal conductivity and dielectric properties suit microwave and RF amplifier parts. Momentive also lists helix support rods for traveling wave tubes. can_do: - label: Density benchmark: density line: The crucible and tube data sheets print 2.0 to 2.19 g/cm3 as bulk density. The NASA study measured 2.12 to 2.19 g/cm3 for high-density CVD BN and 1.76 g/cm3 for low-density CVD BN, so density depends on the deposition conditions. - label: Heat tolerance benchmark: max_service_temp line: The crucible data sheet prints a maximum working temperature of 2200 °C and the tube data sheet 2400 °C, with no atmosphere stated. The sheet page gives 1700 °C as a theoretical value. - label: Strength benchmark: flexural_strength line: The crucible data sheet prints 243.63 MPa flexural strength. The sheet page gives 197 to 244 MPa as theoretical values. The tube data sheet prints 153.86 MPa tensile strength in the parallel direction, while the sheet page gives 80 MPa tensile, also theoretical. - label: Electrical insulation benchmark: dielectric_strength line: The tube data sheet prints a dielectric strength of 56 kV/mm at room temperature. - label: Thermal conduction benchmark: thermal_conductivity line: The crucible data sheet prints thermal conductivity of 43 to 60 W/(m·K) with no direction given. The sheet page's in-plane and through-plane values have no unit printed, so they are not used. compare: Pyrolytic BN is a deposited film, not a pressed powder body. The NASA study reports that hot-pressed BN has randomly oriented crystallites, while CVD BN has its crystal axes aligned along the plate normal, so its properties depend on direction. Its strength figures also differ between datasheets, for example 243.63 MPa on the crucible sheet against 80 MPa tensile, labelled theoretical, on the sheet page. compare_rows: - label: Density (datasheet) benchmark: density - label: Maximum working temperature benchmark: max_service_temp - label: Flexural strength benchmark: flexural_strength handling: - Machining makes dust. Use a particulate mask where nuisance dust is a concern, as the hexagonal BN powder SDS advises. - Keep the material within the working temperature on its data sheet. Oxidation in air at high temperature degrades it, according to the NASA Moore report. - Momentive says pBN can be deposited and then machined into 2D or 3D shapes. good_for: - Crucibles and containers for crystal growth and MBE, where the crucible data sheet prints a working limit of 2200 °C. - Insulating parts in electronic packaging and microwave amplifiers, as the supplier describes them. watch_out: - The datasheets disagree. The crucible sheet prints 243.63 MPa flexural strength, while the sheet page gives 197 to 244 MPa and 80 MPa tensile, all labelled theoretical for the sheet grade. - Oxidation in air at high temperature degrades it. The NASA study reports rapid growth for lower-density CVD BN, and the Moore report found property loss after air oxidation at 1000°C. - No flight or space-environment source was found for pBN. verdict: pBN is a dense, direction-dependent ceramic for high-temperature crucibles and insulators. Its datasheet strengths disagree, and no pBN safety data sheet or space test was found, so check the certificate for the grade you buy.