Pyrolytic boron nitride (pBN) pBN
BN, boron nitride as a CVD deposit of layered, c-axis oriented plates · CAS 10043-11-5
Also known as PBN0922, PBN0923, PBN1343
Pyrolytic boron nitride (pBN) is a dense form of boron nitride deposited from gas by chemical vapour deposition (CVD).
Evidence level
2 of 5
Lab-measured
- 0Predicted only. No one has made it, or no measurement exists.
- 1Calculated. Only calculated or predicted values from sources.
- 2Lab-measured. Measured properties with their conditions stated.
- 3Space-relevant tests. Measured in conditions relevant to space, such as vacuum or atomic oxygen.
- 4Ground-qualified. Qualified for an application on the ground.
- 5Flown or field-proven. Flight or field results exist.
Density
2 to 2.19 g/cm³
Heat tolerance
2200 °C
Strength
243.6 MPa
Electrical insulation
56 kV/mm
Thermal conduction
43 to 60 W/(m·K)
Recipe, share of the weight
- B not statedBoron
- N not statedNitrogen
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)
Risk at a glance
- People None found. Not hazardous per Momentive; no pBN SDS found
- If it fails Moderate. Strength loss after air oxidation
- Corrosion Moderate. Good oxidation resistance in air up to 800°C for a thin PBN coating; properties degrade after air oxidation at 1000°C.
Quick facts: pBN
| Property | Value | Basis |
|---|---|---|
| Density | 1.76 to 2.19 g/cm³ | 3 sourced values across conditions |
| Tensile strength | 154 MPa | 1 sourced value |
| Young's modulus | 18 GPa | 1 sourced value |
| Thermal conductivity | 43 to 60 W/(m·K) | 1 sourced value |
| Maximum service temperature | 2,200 to 2,400 °C | 2 sourced values across conditions |
What is the density of Pyrolytic boron nitride (pBN)?
Pyrolytic boron nitride (pBN) has a density of 1.76 to 2.19 g/cm³. The range covers 3 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the thermal conductivity of Pyrolytic boron nitride (pBN)?
Pyrolytic boron nitride (pBN) has a thermal conductivity of 43 to 60 W/(m·K). The source and test conditions are listed in the properties table on this page.
What is the tensile strength of Pyrolytic boron nitride (pBN)?
Pyrolytic boron nitride (pBN) has a tensile strength of 154 MPa. The source and test conditions are listed in the properties table on this page.
What is the Young's modulus of Pyrolytic boron nitride (pBN)?
Pyrolytic boron nitride (pBN) has a Young's modulus of 18 GPa. The source and test conditions are listed in the properties table on this page.
What is the maximum service temperature of Pyrolytic boron nitride (pBN)?
Pyrolytic boron nitride (pBN) has a maximum service temperature of 2,200 to 2,400 °C. The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What are the other names and codes for Pyrolytic boron nitride (pBN)?
Pyrolytic boron nitride (pBN) is also written as PBN0922, PBN0923, PBN1343. Each code is printed in the source listed beside it in the designations table.
What is Pyrolytic boron nitride (pBN) used for?
Uses recorded in the sources include Crucibles and containers for compound-semiconductor crystal growth and for MBE and MOCVD equipment; Insulating and heat-spreading parts for LEDs and laser diodes; Insulating parts in microwave and RF amplifiers.
Why it exists
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.
Where it's used
Crystal growth and MBE equipment
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.
LEDs and laser diodes
Stanford Advanced Materials says PBN sheets provide insulation and heat dissipation for high-performance semiconductor devices, including LEDs and laser diodes.
Microwave and RF amplifiers
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.
Recipe
BN, boron nitride as a CVD deposit of layered, c-axis oriented plates
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.
| Ingredient | Share of the weight | What it does |
|---|---|---|
| Boron B | not stated | Supplied from boron trichloride in the gas phase. Forms the boron atom in each BN unit. |
| Nitrogen N | not stated | Supplied from ammonia. Forms the nitrogen atom in each BN unit; during oxidation it leaves as N2. |
Weight shares are as printed in the sources.
What it can do
Density
2 to 2.19 g/cm³
measured
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.
Heat tolerance
2200 °C
measured
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.
Strength
243.6 MPa
measured
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.
Electrical insulation
56 kV/mm
measured
The tube data sheet prints a dielectric strength of 56 kV/mm at room temperature.
Thermal conduction
43 to 60 W/(m·K)
measured
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.
How it compares
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.
The same measurements for each material, so you can compare them. Each row names the key condition under the value; the full conditions and methods are in the numbered notes under Technical details. Other materials are shown beside it; each was measured under its own conditions, so open its page before comparing closely. Compare every grade in the family.
| Measurement | pBN | AlN | h-BN | CrN | AlN-BN | Si3N4 | TiN | ZrN |
|---|---|---|---|---|---|---|---|---|
| Thermal behavior and safety | ||||||||
| Thermal conductivity, pBN crucible grade | 43 to 60 W/(m·K)10 | 140 to 180 W/m•°K | 30 W/(m·K) | no data | 92 W/mK | 24 W/mK | 26.96 W/(m·K) | no data |
| Physical and electrical | ||||||||
| Bulk density, pBN crucible grade | 2 to 2.19 g/cm³1 | 3.26 gm/cc | 2 g/cm³ | 5.9 g/cm³ | 2.88 g/cm³ | 3.18 to 3.3 g/cm³ | no data | 7090 kg m-3 |
| Density, high-density CVD BN (measured) | 2.12 to 2.19 g/cm³2 | 3.26 gm/cc | 2 g/cm³ | 5.9 g/cm³ | 2.88 g/cm³ | 3.18 to 3.3 g/cm³ | no data | 7090 kg m-3 |
| Density, low-density CVD BN (measured) | 1.76 g/cm³3 | 3.26 gm/cc | 2 g/cm³ | 5.9 g/cm³ | 2.88 g/cm³ | 3.18 to 3.3 g/cm³ | no data | 7090 kg m-3 |
| Theoretical density of BN, as printed in the NASA study | 2.27 g/cm³4 | 3.26 gm/cc | 2 g/cm³ | 5.9 g/cm³ | 2.88 g/cm³ | 3.18 to 3.3 g/cm³ | no data | 7090 kg m-3 |
| Temperature behavior | ||||||||
| CVD deposition temperature range, pyrolytic BN | 1400 to 1900 °C17 | no data | no data | 200 to 450 °C | no data | no data | no data | no data |
| CVD coating temperature, PBN on Nicalon yarn | 1080 °C18 | no data | no data | 200 to 450 °C | no data | no data | no data | no data |
| Other measurements | ||||||||
| Flexural strength, pBN crucible grade | 243.6 MPa5 | 320 MPa | 94 MPa | no data | 300 MPa | 670 MPa | no data | no data |
| Bending strength, pBN sheet grade (theoretical) | 197 to 244 MPa6 | 320 MPa | 94 MPa | no data | 300 MPa | 670 MPa | no data | no data |
| Tensile strength, pBN tube grade, parallel direction | 153.9 MPa7 | no data | no data | no data | no data | no data | no data | no data |
| Tensile strength, pBN sheet grade (theoretical) | 80 MPa8 | no data | no data | no data | no data | no data | no data | no data |
| Elastic modulus, pBN sheet grade (theoretical) | 18 GPa9 | 330 GPa | 47 GPa | 200 GPa | 176 GPa | 290 GPa | 500 GPa | no data |
| Dielectric strength at room temperature, pBN tube grade | 56 kV/mm11 | 17 ac-kv/mm | 88 kV/mm | no data | 65 kV/mm | no data | no data | no data |
| Dielectric strength at room temperature, pBN sheet grade (theoretical) | 56 kV/mm12 | 17 ac-kv/mm | 88 kV/mm | no data | 65 kV/mm | no data | no data | no data |
| Maximum working temperature, pBN crucible grade | 2200 °C13 | no data | 850 °C | 700 °C | 1000 °C | 1200 °C | no data | no data |
| Maximum working temperature, pBN tube grade | 2400 °C14 | no data | 850 °C | 700 °C | 1000 °C | 1200 °C | no data | no data |
| Maximum operating temperature, pBN sheet grade (theoretical) | 1700 °C15 | no data | 850 °C | 700 °C | 1000 °C | 1200 °C | no data | no data |
| Purity, pBN crucible grade | 99.9 %16 | no data | no data | no data | no data | no data | no data | no data |
Why choose it, and why not
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 for
- 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.
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.
Technical details
For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.
Other names and standards
The same grade under other systems, as datasheets and standards print them. Each code was checked against the page it comes from.
| System | Codes |
|---|---|
| Trade name | PBN0922, PBN0923, PBN1343 |
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Bulk density, pBN crucible grade | Bulk density printed as 2.0-2.19g/cm3 in the supplier technical data sheet | form pyrolytic BN crucible, catalog PBN0922unit in source g/cm3note datasheet does not say whether the figure is measured or theoretical | — |
| 2 | Density, high-density CVD BN (measured) | 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 | form high-density CVD BN plate, pyrolytic BN from BCl3 and NH3unit in source gm/ccbasis measured densities of each BN type studied (Table I caption) | — |
| 3 | Density, low-density CVD BN (measured) | Measured density printed in Table I of the NASA oxidation study | form low-density CVD BN plateunit in source gm/ccbasis measured densities of each BN type studied (Table I caption) | — |
| 4 | Theoretical density of BN, as printed in the NASA study | Row labelled Theoretical in Table I of the NASA oxidation study | basis theoretical value printed in Table I; not a measured valueunit in source gm/cc | — |
| 5 | Flexural strength, pBN crucible grade | Value printed in the Flexural Strength (Mpa) row of the supplier technical data sheet | form pyrolytic BN crucible, catalog PBN0922temperature not stateddirection not statedunit in source Mpa | — |
| 6 | Bending strength, pBN sheet grade (theoretical) | Bending Strength printed as 197-244 N/mm2 on the supplier sheet page, under a note that the values are theoretical | form pyrolytic BN sheet, catalog PBN1343unit in source N/mm2basis the page states that its values are based on theoretical values | — |
| 7 | Tensile strength, pBN tube grade, parallel direction | Value printed as 153.86 (parallel) in the Tensile Strength row of the supplier technical data sheet | form pyrolytic BN tube, catalog PBN0923direction parallel (direction as printed; not defined on the datasheet)unit in source N/mm2 | — |
| 8 | Tensile strength, pBN sheet grade (theoretical) | Tensile Strength printed as 80 N/mm2 on the supplier sheet page; it disagrees with the tube data sheet value above | form pyrolytic BN sheet, catalog PBN1343unit in source N/mm2basis the page states that its values are based on theoretical values | — |
| 9 | Elastic modulus, pBN sheet grade (theoretical) | Elastic Modulus printed as 18 GPa on the supplier sheet page | form pyrolytic BN sheet, catalog PBN1343basis the page states that its values are based on theoretical values | — |
| 10 | Thermal conductivity, pBN crucible grade | Range printed as 43-60 in the Thermal Conductivity row of the supplier technical data sheet | form pyrolytic BN crucible, catalog PBN0922direction not statedtemperature not statedunit in source W/M·k | — |
| 11 | Dielectric strength at room temperature, pBN tube grade | Value printed in the Dielectric Strength (RT) row of the supplier technical data sheet | form pyrolytic BN tube, catalog PBN0923temperature room temperature (RT, as printed)unit in source KV/mm | — |
| 12 | Dielectric strength at room temperature, pBN sheet grade (theoretical) | Dielectric Strength (RT) printed as 56 KV/mm on the supplier sheet page | form pyrolytic BN sheet, catalog PBN1343temperature room temperature (RT, as printed)basis the page states that its values are based on theoretical values | — |
| 13 | Maximum working temperature, pBN crucible grade | Max. Working Temperature printed as 2200℃ in the supplier technical data sheet | form pyrolytic BN crucible, catalog PBN0922atmosphere not statedunit in source ℃ | — |
| 14 | Maximum working temperature, pBN tube grade | Max. Working Temperature printed as 2400℃ in the supplier technical data sheet | form pyrolytic BN tube, catalog PBN0923atmosphere not statedunit in source ℃ | — |
| 15 | Maximum operating temperature, pBN sheet grade (theoretical) | Max. Operating Temp. printed as 1700 ℃ in the supplier sheet specification table, under the theoretical-values note | form pyrolytic BN sheet, catalog PBN1343atmosphere not statedbasis the page states that its values are based on theoretical valuesunit in source ℃ | — |
| 16 | Purity, pBN crucible grade | Purity printed as 99.9% in the supplier technical data sheet header | form pyrolytic BN crucible, catalog PBN0922 | — |
| 17 | CVD deposition temperature range, pyrolytic BN | Deposition temperatures printed as about 1900°C down to about 1400°C in the Starting Materials section of the NASA oxidation study | process CVD of pyrolytic BN from BCl3 and NH3note the lower limit is printed with OCR garbling in the copy read; 1400°C also appears in another line of the same paper | — |
| 18 | CVD coating temperature, PBN on Nicalon yarn | Printed as around 1080°C in the Introduction section of the NASA final report (thin coating on fibre, not bulk pBN) | process PBN coating from BCl3 and ammonia on Nicalon NL 202 yarnnote most coatings made at this temperature to limit thermal damage to the yarn | — |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Air at high temperature, thin PBN coating on Nicalon fibre | moderate | Good oxidation resistance in air up to 800°C for a thin PBN coating; properties degrade after air oxidation at 1000°C.1 |
| Oxygen at high temperature, dense and low-density CVD BN (thermogravimetric tests) | moderate | Dense, well-ordered CVD BN oxidizes slowly; lower-density CVD BN oxidizes much faster.2 |
| Trace water vapour in the oxygen stream | moderate | Trace water vapour makes oxidation of dense CVD BN paralinear.3 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Air at high temperature, thin PBN coating on Nicalon fibre | 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. | form PBN coating 0.1-0.7 microns on Nicalon NL 202 yarntest air oxidation at the stated temperatures |
| 2 | Oxygen at high temperature, dense and low-density CVD BN (thermogravimetric tests) | 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.” | atmosphere 100% oxygen, thermogravimetric tests (rate constants not recorded: printed with exponents) |
| 3 | Trace water vapour in the oxygen stream | 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.” | water vapour about 20 ppm, as printed |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
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.
- The material
- 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.
- Toxicology
- The same hexagonal BN SDS states that its toxicological properties have not been thoroughly investigated.
- Dust
- Machining makes dust. The hexagonal BN SDS advises a particulate mask only where nuisance dust is a concern.
If it oxidizes in air
The oxidation tests in these sources were run in air or oxygen at high temperature. They are laboratory results, not field incidents.
- Products
- 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.
- Dense material
- The NASA study describes high-density CVD BN as oxidizing slowly, according to a parabolic rate law.
- Thin coating
- 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.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Strength loss after air oxidationmoderate severity | Heating in air at 1000°C (thin PBN coating on Nicalon yarn)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. |
| Fast oxidation of low-density CVD BNmoderate severity | Heating in oxygen at high temperatureThe NASA study reports rapid linear growth for lower-density CVD BN, which is recorded here at 1.76 g/cm3 (Table I). |
Side effects on surrounding parts
| Affects | Effect |
|---|---|
| Off-gas from a hot zone that contains air or oxygen | Oxidation releases nitrogen, and the paper notes that “N2(g) may also further oxidize to NOx(g).” |
Handling and storage
- Momentive says pBN can be deposited and then machined into 2D or 3D shapes.
- Machining makes dust. The hexagonal BN powder SDS advises a particulate mask only where nuisance dust is a concern.
Supply and geography
How common the raw materials are and where they come from.
Boron
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).
- Top producers (2025)
- Turkey, Bolivia, Peru, Chile, China, Argentina, Russia, Germany
- Critical mineral lists
- US: listed
- 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.
Documents
Datasheets, safety data sheets, papers and standards you can open.
Full record
The complete spore, as stored. Free to reuse under CC-BY-4.0. Images keep the licence shown with each one.
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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.
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.