Boron nitride nanotubes BNNT
BN, one boron and one nitrogen atom per formula unit, arranged as nanotubes · CAS 10043-11-5
Boron nitride nanotubes (BNNTs) are hollow tubes built from boron and nitrogen atoms.
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.
Stiffness
760 to 960 GPa
Heat in air
900 °C onset
Density
0.27 to 0.3 g/cm3 (mat and disc forms)
Neutron capture
3835 barn
Recipe, share of the weight
- B 43.6%Boron
- N 56.4%Nitrogen
Best for
Lightweight, electrically insulating filler studied for radiation shielding and heat-resistant parts, where the evidence so far is modelling, single-tube tests and ground tests rather than flight
Weakest at
Few measured values for BNNT itself: the NASA comparison values are theoretical, its thermal conductivity and shielding performance were not measured in the sources read, and the sources disagree on several values
Risk at a glance
- People Moderate. Irritant dust; long-term toxicity unknown
- If it fails Moderate. Oxidation of single tubes in hot air
- Corrosion Moderate. Single BNNTs survived 850 °C in air for 10 minutes and began to oxidise at 900 °C.
Quick facts: BNNT
| Property | Value | Basis |
|---|---|---|
| Density | 0.27 to 0.3 g/cm³ | 2 sourced values across conditions |
| Tensile strength | 14,000 to 38,000 MPa | 1 sourced value |
| Young's modulus | 760 to 1,800 GPa | 3 sourced values across conditions |
| Thermal conductivity | 300 to 3,000 W/(m·K) | 1 sourced value |
| Thermal expansion (CTE) | -1 ppm/K | 1 sourced value |
| Melting point | 2,973 °C | 1 sourced value |
What is the density of Boron nitride nanotubes (BNNT)?
Boron nitride nanotubes (BNNT) has a density of 0.27 to 0.3 g/cm³. 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 is the thermal conductivity of Boron nitride nanotubes (BNNT)?
Boron nitride nanotubes (BNNT) has a thermal conductivity of 300 to 3,000 W/(m·K). The source and test conditions are listed in the properties table on this page.
What is the coefficient of thermal expansion of Boron nitride nanotubes (BNNT)?
Boron nitride nanotubes (BNNT) has a coefficient of thermal expansion of -1 ppm/K. The source and test conditions are listed in the properties table on this page.
What is the melting point of Boron nitride nanotubes (BNNT)?
Boron nitride nanotubes (BNNT) has a melting point of 2,973 °C. The source and test conditions are listed in the properties table on this page.
What is the tensile strength of Boron nitride nanotubes (BNNT)?
Boron nitride nanotubes (BNNT) has a tensile strength of 14,000 to 38,000 MPa. The source and test conditions are listed in the properties table on this page.
What is Boron nitride nanotubes (BNNT) used for?
Uses recorded in the sources include Hydrogen-containing BNNT as a shield (modelled); Choice of shielding material (literature review); BNNT and BNNT polymer composites in a neutron exposure lab (ground).
Why it exists
Boron nitride nanotubes (BNNTs) are being studied by NASA Langley as a multifunctional material: stiff, heat-resistant tubes that also insulate electrically. NASA's overview lists neutron shielding from their boron content, and a high service temperature above 800 °C, as benefits. NASA's Phase I study tested by modelling whether hydrogen-containing BNNT could shield cosmic rays better than polyethylene at the same thickness.
Where it's used
Radiation shielding (modelled)
NASA's Phase I modelling found that BN with 5% hydrogen could shield galactic cosmic rays better than polyethylene of the same wall thickness. This is a calculated result, not a measurement.
Heat test sample (ground)
NASA exposed an as-grown BNNT mat to a surface temperature of 1315 °C for 1 minute in an arc-jet test. The text we read gives no pass or fail number.
Neutron shielding composites (ground)
NASA's overview reports excellent neutron shielding for BNNT and BNNT polymer composites in lab tests, but the slides we read give no numeric result.
Recipe
BN, one boron and one nitrogen atom per formula unit, arranged as nanotubes
Boron nitride nanotubes are made of boron and nitrogen in a one-to-one atom ratio. NASA's high-temperature, high-pressure method vaporises boron feedstock with a laser in nitrogen gas, with no catalyst, so boron and nitrogen are the only reactants.
| Ingredient | Atoms per unit | Share of the weight | What it does |
|---|---|---|---|
| Boron B | 1 | 43.6% | Forms the tube wall with nitrogen. Its boron-10 isotope has a large thermal-neutron absorption cross section, which is why boron is used in neutron shielding. |
| Nitrogen N | 1 | 56.4% | Forms the tube wall with boron. Nitrogen has a larger neutron absorption cross section than carbon (NIAC report). |
Weight shares are calculated from standard atomic weights.
What it can do
Stiffness
760 to 960 GPa
measured
Individual high-temperature, high-pressure tubes measured in NASA's in-situ SEM tests have an elastic modulus of 760 to 960 GPa. NASA's theoretical table gives 1.18 TPa as a theoretical nanotube value.
Heat in air
900 °C onset
measured
Single tubes survived 10 minutes in air at 850 °C with no change, and the first oxidation appeared at 900 °C (Chen et al. 2017).
Density
0.27 to 0.3 g/cm3 (mat and disc forms)
measured
As-grown mats and target discs of BNNT have densities of about 0.3 g/cm3 and 0.27 g/cm3. A NASA report gives 1.3 to 1.4 g/cm3 for the solid tube, without a cited test.
Neutron capture
3835 barn
worked out from the formula
Boron-10 has a thermal-neutron absorption cross section of 3835 barns, as quoted in the NIAC report. That figure is for the isotope, not a measured BNNT shield.
How it compares
Relative to carbon nanotubes, NASA's theoretical table gives BNNTs a much higher oxidation resistance in air, stable to over 900 °C against 300 to 400 °C for carbon nanotubes, and a wide electrical band gap, where carbon nanotubes are metallic or semiconducting. The same table gives BNNTs a lower theoretical Young's modulus and thermal conductivity than carbon nanotubes. Measured values for single tubes are below the theoretical table values, so the table should not be read as a measured result.
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. Compare every grade in the family.
| Measurement | BNNT |
|---|---|
| Thermal behavior and safety | |
| Thermal conductivity, theoretical nanotube value | 300 to 3000 W/mK2 |
| Oxidation onset in air, single BNNT, 10 minutes | 900 °C13 |
| Melting point, BNNT product in a supplier SDS | 2973 °C18 |
| Physical and electrical | |
| Bulk density, as-grown nonwoven BNNT mat | 0.3 g/cm³15 |
| Average density, BNNT target discs for radioisotope production | 0.27 g/cm³16 |
| Density of the solid BNNT tube, stated in a NASA report | 1.3 to 1.4 g/cm³17 |
| Temperature behavior | |
| Thermal oxidation resistance in air, theoretical nanotube value | > 900 °C4 |
| Oxidation resistance in air quoted as about 900 °C in a review | 900 °C11 |
| Temperature single BNNTs survived in air for 10 minutes | 850 °C12 |
| Air survival temperature quoted in a review | 800 °C14 |
| Stability in air, BNNT product in a supplier SDS | > 850 °C19 |
| Other measurements | |
| Young's modulus, theoretical nanotube value | 1.18 TPa1 |
| Coefficient of thermal expansion, theoretical nanotube value | -1 ppm/K3 |
| Band gap, theoretical nanotube value | 6 eV5 |
| Thermal-neutron absorption cross section, boron-10 isotope | 3835 barn6 |
| Young's modulus of individual HTP-BNNTs, in-situ SEM tensile test | 760 to 960 GPa7 |
| Breaking strength of individual HTP-BNNTs, in-situ SEM tensile test | 14 to 38 GPa8 |
| Young's modulus quoted as up to 1.3 TPa in a review | < 1.3 TPa9 |
| Young's modulus of 1.8 TPa quoted in a review | 1.8 TPa10 |
| Median outer diameter, HTP-BNNT, as reported by Chen et al. | 2.9 nm20 |
| Outer diameter range and wall count, HTP-BNNTStatement in the introduction of the paper | 1 to 6 nm |
| Typical outer diameter quoted for CVD and thermal-annealing BNNTs | 50 to 80 nm21 |
Why choose it, and why not
Good for
- Radiation shielding research. Hydrogen-containing BNNT was modelled to beat polyethylene at the same thickness (calculated, not measured).
- Heat-resistant insulating parts. Single tubes survived 850 °C in air for 10 minutes with no change.
Watch out for
- Most property values are theoretical, from one tube at a time, or from a single lab test. The sources disagree on several values, such as 800 °C against 850 °C for survival in air, and 1.3 TPa against 1.8 TPa for modulus.
- The SDS classes the powder as an irritant and says the nanotube toxicity is not known.
- The shielding figures are modelled. No measured BNNT shielding number was found in the sources read.
BNNT looks promising for heat-resistant, insulating and radiation-shielding parts, but the evidence is mostly theory, single-tube tests and modelling, so it is not yet a qualified material for spacecraft use.
Technical details
For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Young's modulus, theoretical nanotube value | Theoretical value printed in a NASA Langley overview table | basis theoretical nanotube value from the NASA comparison tabletable note table caption says nanotube values are theoretical | — |
| 2 | Thermal conductivity, theoretical nanotube value | Theoretical value printed in a NASA Langley overview table | basis theoretical nanotube value, printed as about 300 to 3000 W/mKtemperature not stated | — |
| 3 | Coefficient of thermal expansion, theoretical nanotube value | Theoretical value printed in a NASA Langley overview table | basis theoretical nanotube valueunit in source x10-6 K-1 | — |
| 4 | Thermal oxidation resistance in air, theoretical nanotube value | Theoretical value printed in a NASA Langley overview table; Chen et al. measured oxidation onset at 900 °C on single tubes | atmosphere airbasis printed as stable to over 900 °C in air in the theoretical table | The same table gives carbon nanotubes as stable up to 300 to 400 °C in air, for comparison. |
| 5 | Band gap, theoretical nanotube value | Theoretical value printed in a NASA Langley overview table | basis theoretical value printed as about 6.0 eVcharacter wide band gap, electrically insulating | — |
| 6 | Thermal-neutron absorption cross section, boron-10 isotope | Nuclear data value quoted in a NASA Langley Phase I report | isotope boron-10basis isotope value quoted in the NIAC report, not a measurement on BNNT | — |
| 7 | Young's modulus of individual HTP-BNNTs, in-situ SEM tensile test | Measured on individual tubes by in-situ SEM nanomechanical tensile testing, per the NASA Langley overview | form individual HTP-BNNT tube, tested one tube at a timediameter median 2.5 nm by AFMtest in-situ SEM tensile test | — |
| 8 | Breaking strength of individual HTP-BNNTs, in-situ SEM tensile test | Measured on individual tubes by in-situ SEM nanomechanical tensile testing, per the NASA Langley overview | form individual HTP-BNNT tube, tested one tube at a timediameter median 2.5 nm by AFMnote single-tube breaking strength, not a bulk material value | — |
| 9 | Young's modulus quoted as up to 1.3 TPa in a review | Second-hand figure stated in the introduction of an open-access review | basis stated as up to 1.3 TPa with no test condition; the review cites a 1998 paper on multi-wall BNNTs | Second-hand figure. It differs from the 1.8 TPa in the same review and from the NASA single-tube values; all are reported side by side. |
| 10 | Young's modulus of 1.8 TPa quoted in a review | Statement in the introduction of an open-access review, citing a 2013 study | basis multi-wall BNNT value from a cited bending study; the review does not separate Young's modulus from bending modulus | Uncertainty: ± 0.3 TPaSecond-hand figure. It differs from the 760 to 960 GPa measured on individual HTP tubes by NASA. |
| 11 | Oxidation resistance in air quoted as about 900 °C in a review | Statement in Section 2.5 of an open-access review, without its own citation | atmosphere airbasis printed as resistive to oxidation up to about 900 °C; no test conditions given | Approximate figure, printed with a tilde in the source. |
| 12 | Temperature single BNNTs survived in air for 10 minutes | AFM of single tubes after 10 minutes at each temperature in air | atmosphere airtime 10 minutessample single tube, AFMoutcome no morphology change | — |
| 13 | Oxidation onset in air, single BNNT, 10 minutes | AFM of single tubes after 10 minutes at 900 °C in air | atmosphere airtime 10 minutessample single tube, AFMoutcome broken segment about 30 nm long | — |
| 14 | Air survival temperature quoted in a review | Statement in the introduction of an open-access review | atmosphere airbasis stated as stable up to 800 °C in air; no test conditions or citation in that sentence | Disagrees with the 850 °C survival and 900 °C onset that Chen et al. measured on single tubes. The same review also gives about 900 °C in Section 2.5. |
| 15 | Bulk density, as-grown nonwoven BNNT mat | Density printed for a test sample on a NASA Langley hypersonic arc-jet test slide | form as-grown nonwoven mat, vacuum-filtered, 2 mm thickvalue note printed as about 0.3 g/cm3 | — |
| 16 | Average density, BNNT target discs for radioisotope production | Average density printed on a NASA Langley slide for BNNT target media | form multi-stack of natural-enrichment BNNT target discsbasis average density printed on the slide | — |
| 17 | Density of the solid BNNT tube, stated in a NASA report | Literature value stated in the text of a NASA Langley Phase I report | form solid nanotube, not a matbasis sentence in the NIAC report with no test or citation | Not measured in the report and not sourced in the sentence. The 0.27 and 0.3 g/cm3 values above are for mat and disc forms, not solid tubes. |
| 18 | Melting point, BNNT product in a supplier SDS | Listed in a supplier safety data sheet, section 9 | material BNNT product as described in the SDS, about 60% BNNT and about 10% hexagonal boron nitride by SDS composition | Supplier figure for a mixed product, not a measurement on pure nanotubes. |
| 19 | Stability in air, BNNT product in a supplier SDS | Listed as stability in air in a supplier safety data sheet, section 9 | atmosphere airmaterial BNNT product as described in the SDS | Supplier figure printed as more than 850 °C; the SDS gives no test time. |
| 20 | Median outer diameter, HTP-BNNT, as reported by Chen et al. | Reported median value stated in the Raman section of the paper | basis median diameter given as reported for HTP-BNNTs in the paper's Raman section | Differs from the 2.5 nm median used in NASA's tensile table. Both are reported. |
| 21 | Typical outer diameter quoted for CVD and thermal-annealing BNNTs | Statement in Section 2.1 of an open-access review, without its own citation | synthesis CVD and thermal annealing methodsbasis printed as the typical diameter of tubes from those methods | A different synthesis route from the HTP tubes (2.5 to 2.9 nm). Recorded as printed for comparison, not as an HTP value. |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Air at high temperature (oxidation) | moderate | Single BNNTs survived 850 °C in air for 10 minutes and began to oxidise at 900 °C.1 |
| Vacuum and outgassing, and fire | moderate | NASA's NIAC report says BNNT has outgassing and flammability issues and should be encapsulated.2 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Air at high temperature (oxidation) | In AFM tests of single tubes heated for 10 minutes in air, there was no morphology change at 850 °C, a broken segment about 30 nm long at 900 °C, severe length loss and breaks at 925 °C, and severe burnout at 950 °C. In in-situ optical tests of microfibrils, the edges changed at 1000 °C and the material was largely burned out at 1200 °C. | atmosphere airexposure 10 minutes per temperature for single-tube AFM tests |
| 2 | Vacuum and outgassing, and fire | The NIAC Phase I report states that BNNT has some outgassing and flammability issues and should be encapsulated for many applications. | — |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
The supplier safety data sheet classes BNNT powder as an irritant. The toxicity of the nanotube form is not known.
- The powder
- The safety data sheet classes the BNNT product as an irritant for eyes, skin and airways, and gives no GHS classification. Its oral LD50 in rats is above 50 g/kg.
- Dust
- Avoid breathing the dust. The SDS says frequent inhalation over a long period increases the risk of lung disease.
- Unknowns
- The SDS says the acute and chronic toxicity of the nanotube component is not known and may differ with the number of walls.
If a part overheats
These results come from heating tests on single tubes and microfibrils in air, not from field use.
- Air at 850 °C
- Individual tubes showed no morphology change after 10 minutes in air at 850 °C.
- Air at 900 °C
- After 10 minutes at 900 °C a broken segment about 30 nm long appeared, which marks oxidation onset.
- Outgassing
- NASA's NIAC report notes outgassing and flammability issues and recommends encapsulation.
Handling and storage
- Dust
- Avoid dust formation. Use good ventilation or local exhaust, and clean spills with a HEPA-filter vacuum.
- Storage
- Keep the container tightly closed in a cool, well-ventilated area.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Oxidation of single tubes in hot airmoderate severity | Heating in air at 900 °C for 10 minutes (single tube, AFM)A broken segment about 30 nm long appears at 900 °C; severe length loss and breaks follow at 925 °C. |
| Outgassing and flammabilitymoderate severity | Not stated in the NIAC Phase I reportThe report says BNNT should be encapsulated for many applications because of these issues. |
| Dust release during handlingmoderate severity | Handling dry BNNT powder or mat without exhaust ventilationDust can irritate the eyes, skin and airways. The SDS gives no OSHA exposure limit (no data available). |
Side effects on surrounding parts
| Affects | Effect |
|---|---|
| People who handle the powder | The SDS warns that the BNNT powder may cause skin sensitization and skin or eye irritation. |
Handling and storage
- Avoid dust formation and keep the container tightly closed in a cool, well-ventilated area (SDS sections 7 and 10).
- Work with good ventilation, under a fume hood or with local exhaust where dust forms, and avoid skin and eye contact (SDS sections 7 and 8).
- Clean up spills with a HEPA-filter vacuum and keep spilt material away from drains (SDS sections 6 and 12).
Mitigations
- Use the respirator class the SDS lists for the expected dust exposure (P95 or P1 for low exposure, P99 or P2 for high), with safety glasses and protective gloves (SDS section 8).
Supply and geography
How common the raw materials are and where they come from.
Boron (feedstock for BNNT)
Crustal abundance not found in the sources read.
- Top producers (2025)
- Turkey, Chile, Bolivia, Peru, China, Russia, Argentina, Germany, United States
- Critical mineral lists
- US: listed, EU: listed
- Recycling
- USGS: boron recycling is insignificant.
- Substitutes
- USGS: other materials can substitute for boron in detergents, enamels, insulation and soaps. No substitute for BNNT was found in the sources read.
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: boron-nitride-nanotubes
spore_version: 0.2
family: carbide-nitride-boride-ceramics
name: Boron nitride nanotubes
abbreviation: BNNT
role: Multifunctional nanotube material for radiation shielding, heat-resistant parts and electrically insulating composites
category: shielding
type: boron-nitride-nanotubes
summary: Boron nitride nanotubes (BNNTs) are hollow tubes built from boron and nitrogen atoms. In NASA Langley's in-situ scanning electron microscope tensile tests, individual high-temperature, high-pressure (HTP) BNNTs with a median diameter of 2.5 nm had an elastic modulus of 760 to 960 GPa and a breaking strength of 14 to 38 GPa. Single tubes survived 850 °C in air for 10 minutes and showed oxidation onset at 900 °C, while the radiation-shielding case rests so far on modelling and ground tests.
best_for: Lightweight, electrically insulating filler studied for radiation shielding and heat-resistant parts, where the evidence so far is modelling, single-tube tests and ground tests rather than flight
weakest_at: 'Few measured values for BNNT itself: the NASA comparison values are theoretical, its thermal conductivity and shielding performance were not measured in the sources read, and the sources disagree on several values'
identity:
formula: BN, one boron and one nitrogen atom per formula unit, arranged as nanotubes
cas: 10043-11-5
source: wiki-bnnt
where: 'Structure: carbon atoms alternately substituted by nitrogen and boron (Wikipedia, lead section). CAS 10043-11-5 is the number the supplier SDS (section 3) prints for the boron nitride ingredient of the BNNT product.'
tags:
environments:
- deep-space
stresses:
- total-radiation-dose
- extreme-heat
- vacuum-and-outgassing
applications:
- radiation-shielding
- heat-shields
- structures
properties:
- benchmark: elastic_modulus
label: Young's modulus, theoretical nanotube value
value: 1.18
unit: TPa
scope: material
conditions:
basis: theoretical nanotube value from the NASA comparison table
table_note: table caption says nanotube values are theoretical
method: Theoretical value printed in a NASA Langley overview table
status: calculated
source: nasa-overview
where: Nanotube Comparison (Theoretical) table, row Mechanical Properties (Young's Modulus), BNNT column
- benchmark: thermal_conductivity
label: Thermal conductivity, theoretical nanotube value
value: 300
value_high: 3000
bound: range
unit: W/mK
scope: material
conditions:
basis: theoretical nanotube value, printed as about 300 to 3000 W/mK
temperature: not stated
method: Theoretical value printed in a NASA Langley overview table
status: calculated
source: nasa-overview
where: Nanotube Comparison (Theoretical) table, row Thermal Conductivity, BNNT column
- benchmark: cte
label: Coefficient of thermal expansion, theoretical nanotube value
value: -1
unit: ppm/K
scope: material
conditions:
basis: theoretical nanotube value
unit_in_source: x10-6 K-1
method: Theoretical value printed in a NASA Langley overview table
status: calculated
source: nasa-overview
where: Nanotube Comparison (Theoretical) table, row Coefficient of Thermal Expansion
- benchmark: oxidation_resistance_temperature
label: Thermal oxidation resistance in air, theoretical nanotube value
value: 900
bound: lower
unit: °C
scope: material
conditions:
atmosphere: air
basis: printed as stable to over 900 °C in air in the theoretical table
method: Theoretical value printed in a NASA Langley overview table; Chen et al. measured oxidation onset at 900 °C on single tubes
status: calculated
source: nasa-overview
where: Nanotube Comparison (Theoretical) table, row Thermal Oxidation Resistance, BNNT column
note: The same table gives carbon nanotubes as stable up to 300 to 400 °C in air, for comparison.
- benchmark: band_gap
label: Band gap, theoretical nanotube value
value: 6
unit: eV
scope: material
conditions:
basis: theoretical value printed as about 6.0 eV
character: wide band gap, electrically insulating
method: Theoretical value printed in a NASA Langley overview table
status: calculated
source: nasa-overview
where: Nanotube Comparison (Theoretical) table, row Electric Properties, BNNT column
- benchmark: neutron_capture_cross_section
label: Thermal-neutron absorption cross section, boron-10 isotope
value: 3835
unit: barn
scope: material
conditions:
isotope: boron-10
basis: isotope value quoted in the NIAC report, not a measurement on BNNT
method: Nuclear data value quoted in a NASA Langley Phase I report
status: calculated
source: nasa-niac-2012
where: Introduction, text on neutron absorption by boron and nitrogen
- benchmark: elastic_modulus
label: Young's modulus of individual HTP-BNNTs, in-situ SEM tensile test
value: 760
value_high: 960
bound: range
unit: GPa
scope: material
conditions:
form: individual HTP-BNNT tube, tested one tube at a time
diameter: median 2.5 nm by AFM
test: in-situ SEM tensile test
method: Measured on individual tubes by in-situ SEM nanomechanical tensile testing, per the NASA Langley overview
status: ground
source: nasa-overview
where: BNNT Tensile Test Results table, row D = 2.5 nm, column Elastic modulus
- benchmark: ultimate_tensile_strength
label: Breaking strength of individual HTP-BNNTs, in-situ SEM tensile test
value: 14
value_high: 38
bound: range
unit: GPa
scope: material
conditions:
form: individual HTP-BNNT tube, tested one tube at a time
diameter: median 2.5 nm by AFM
note: single-tube breaking strength, not a bulk material value
method: Measured on individual tubes by in-situ SEM nanomechanical tensile testing, per the NASA Langley overview
status: ground
source: nasa-overview
where: BNNT Tensile Test Results table, row D = 2.5 nm, column Breaking Strength
- benchmark: elastic_modulus
label: Young's modulus quoted as up to 1.3 TPa in a review
value: 1.3
bound: upper
unit: TPa
scope: material
conditions:
basis: stated as up to 1.3 TPa with no test condition; the review cites a 1998 paper on multi-wall BNNTs
method: Second-hand figure stated in the introduction of an open-access review
status: ground
note: Second-hand figure. It differs from the 1.8 TPa in the same review and from the NASA single-tube values; all are reported side by side.
source: molecules2016
where: Section 1 (Introduction)
- benchmark: elastic_modulus
label: Young's modulus of 1.8 TPa quoted in a review
value: 1.8
uncertainty: ± 0.3 TPa
unit: TPa
scope: material
conditions:
basis: multi-wall BNNT value from a cited bending study; the review does not separate Young's modulus from bending modulus
method: Statement in the introduction of an open-access review, citing a 2013 study
status: ground
note: Second-hand figure. It differs from the 760 to 960 GPa measured on individual HTP tubes by NASA.
source: molecules2016
where: Section 1 (Introduction)
- benchmark: oxidation_resistance_temperature
label: Oxidation resistance in air quoted as about 900 °C in a review
value: 900
unit: °C
scope: material
conditions:
atmosphere: air
basis: printed as resistive to oxidation up to about 900 °C; no test conditions given
method: Statement in Section 2.5 of an open-access review, without its own citation
status: ground
note: Approximate figure, printed with a tilde in the source.
source: molecules2016
where: Section 2.5
- benchmark: air_survival_temperature
label: Temperature single BNNTs survived in air for 10 minutes
value: 850
unit: °C
scope: material
conditions:
atmosphere: air
time: 10 minutes
sample: single tube, AFM
outcome: no morphology change
method: AFM of single tubes after 10 minutes at each temperature in air
status: ground
source: chen2017
where: Results, temperature table, single-tube AFM row at 850 °C
- benchmark: oxidation_onset_temperature
label: Oxidation onset in air, single BNNT, 10 minutes
value: 900
unit: °C
scope: material
conditions:
atmosphere: air
time: 10 minutes
sample: single tube, AFM
outcome: broken segment about 30 nm long
method: AFM of single tubes after 10 minutes at 900 °C in air
status: ground
source: chen2017
where: Results, temperature table, single-tube AFM row at 900 °C
- benchmark: air_survival_temperature
label: Air survival temperature quoted in a review
value: 800
unit: °C
scope: material
conditions:
atmosphere: air
basis: stated as stable up to 800 °C in air; no test conditions or citation in that sentence
method: Statement in the introduction of an open-access review
status: ground
note: Disagrees with the 850 °C survival and 900 °C onset that Chen et al. measured on single tubes. The same review also gives about 900 °C in Section 2.5.
source: molecules2016
where: Section 1 (Introduction)
- benchmark: density
label: Bulk density, as-grown nonwoven BNNT mat
value: 0.3
unit: g/cm3
scope: material
conditions:
form: as-grown nonwoven mat, vacuum-filtered, 2 mm thick
value_note: printed as about 0.3 g/cm3
method: Density printed for a test sample on a NASA Langley hypersonic arc-jet test slide
status: ground
source: nasa-overview
where: Hypersonic Materials Environmental Test System slide, sample description, Density
- benchmark: density
label: Average density, BNNT target discs for radioisotope production
value: 0.27
unit: g/cm3
scope: material
conditions:
form: multi-stack of natural-enrichment BNNT target discs
basis: average density printed on the slide
method: Average density printed on a NASA Langley slide for BNNT target media
status: ground
source: nasa-overview
where: Target media slide, Density (average) label
- benchmark: density
label: Density of the solid BNNT tube, stated in a NASA report
value: 1.3
value_high: 1.4
bound: range
unit: g/cm3
scope: material
conditions:
form: solid nanotube, not a mat
basis: sentence in the NIAC report with no test or citation
method: Literature value stated in the text of a NASA Langley Phase I report
status: calculated
note: Not measured in the report and not sourced in the sentence. The 0.27 and 0.3 g/cm3 values above are for mat and disc forms, not solid tubes.
source: nasa-niac-2012
where: Introduction, paragraph on BNNT as a structural material (molecular nanotube structure)
- benchmark: melting_point
label: Melting point, BNNT product in a supplier SDS
value: 2973
unit: °C
scope: material
conditions:
material: BNNT product as described in the SDS, about 60% BNNT and about 10% hexagonal boron nitride by SDS composition
method: Listed in a supplier safety data sheet, section 9
status: ground
note: Supplier figure for a mixed product, not a measurement on pure nanotubes.
source: sds-bnnt
where: Section 9, Other information, Melting point
- benchmark: stability_in_air_temperature
label: Stability in air, BNNT product in a supplier SDS
value: 850
bound: lower
unit: °C
scope: material
conditions:
atmosphere: air
material: BNNT product as described in the SDS
method: Listed as stability in air in a supplier safety data sheet, section 9
status: ground
note: Supplier figure printed as more than 850 °C; the SDS gives no test time.
source: sds-bnnt
where: Section 9, Physical and chemical properties, Stability in air
- benchmark: median_outer_diameter
label: Median outer diameter, HTP-BNNT, as reported by Chen et al.
value: 2.9
unit: nm
scope: material
conditions:
basis: median diameter given as reported for HTP-BNNTs in the paper's Raman section
method: Reported median value stated in the Raman section of the paper
status: ground
note: Differs from the 2.5 nm median used in NASA's tensile table. Both are reported.
source: chen2017
where: Results, Raman spectroscopy section
- benchmark: outer_diameter_range
label: Outer diameter range and wall count, HTP-BNNT
value: 1
value_high: 6
bound: range
unit: nm
scope: material
conditions:
fraction: '>97% of HTP-BNNTs'
walls: one to four walls
method: Statement in the introduction of the paper
status: ground
source: chen2017
where: Introduction
- benchmark: typical_outer_diameter
label: Typical outer diameter quoted for CVD and thermal-annealing BNNTs
value: 50
value_high: 80
bound: range
unit: nm
scope: material
conditions:
synthesis: CVD and thermal annealing methods
basis: printed as the typical diameter of tubes from those methods
method: Statement in Section 2.1 of an open-access review, without its own citation
status: ground
note: A different synthesis route from the HTP tubes (2.5 to 2.9 nm). Recorded as printed for comparison, not as an HTP value.
source: molecules2016
where: Section 2.1
corrosion:
- environment: Air at high temperature (oxidation)
headline: Single BNNTs survived 850 °C in air for 10 minutes and began to oxidise at 900 °C.
effect: In AFM tests of single tubes heated for 10 minutes in air, there was no morphology change at 850 °C, a broken segment about 30 nm long at 900 °C, severe length loss and breaks at 925 °C, and severe burnout at 950 °C. In in-situ optical tests of microfibrils, the edges changed at 1000 °C and the material was largely burned out at 1200 °C.
rating: moderate
conditions:
atmosphere: air
exposure: 10 minutes per temperature for single-tube AFM tests
source: chen2017
where: Results, temperature table (single-tube and microfibril rows)
- environment: Vacuum and outgassing, and fire
headline: NASA's NIAC report says BNNT has outgassing and flammability issues and should be encapsulated.
effect: The NIAC Phase I report states that BNNT has some outgassing and flammability issues and should be encapsulated for many applications.
rating: moderate
source: nasa-niac-2012
where: Introduction, paragraph on BNNT as a structural material
risks:
hazards:
- text: 'Supplier safety data sheet for BNNT (Raymor Industries Inc., print date 14 December 2021) gives GHS classification as not available, signal word Warning, and an irritant classification (Xi, risk phrase R36/37/38: irritating to eyes, respiratory system and skin).'
ghs: []
source: sds-bnnt
where: Section 2, Hazards identification; Section 15, EU regulations
- text: The same SDS gives an oral LD50 in rats above 50 g/kg for the BNNT product. It states that the acute and chronic toxicity of the BNNT component is not known and may differ with wall number.
ghs: []
source: sds-bnnt
where: Section 11, Toxicological information
- text: The SDS says inhalation of dust irritates the airways and that frequent inhalation of dust over a long period increases the risk of lung disease.
ghs: []
source: sds-bnnt
where: Sections 4 and 11
failure_risks:
- mode: Oxidation of single tubes in hot air
trigger: Heating in air at 900 °C for 10 minutes (single tube, AFM)
consequence: A broken segment about 30 nm long appears at 900 °C; severe length loss and breaks follow at 925 °C.
severity: moderate
source: chen2017
where: Results, temperature table
- mode: Outgassing and flammability
trigger: Not stated in the NIAC Phase I report
consequence: The report says BNNT should be encapsulated for many applications because of these issues.
severity: moderate
source: nasa-niac-2012
where: Introduction, paragraph on BNNT as a structural material
- mode: Dust release during handling
trigger: Handling dry BNNT powder or mat without exhaust ventilation
consequence: Dust can irritate the eyes, skin and airways. The SDS gives no OSHA exposure limit (no data available).
severity: moderate
source: sds-bnnt
where: Sections 4 and 8
side_effects:
- text: The SDS warns that the BNNT powder may cause skin sensitization and skin or eye irritation.
affects: People who handle the powder
source: sds-bnnt
where: Section 11, Respiratory or skin sensitization, and Irritant effects
handling:
- text: Avoid dust formation and keep the container tightly closed in a cool, well-ventilated area (SDS sections 7 and 10).
source: sds-bnnt
where: Sections 7 and 10
- text: Work with good ventilation, under a fume hood or with local exhaust where dust forms, and avoid skin and eye contact (SDS sections 7 and 8).
source: sds-bnnt
where: Sections 7 and 8
- text: Clean up spills with a HEPA-filter vacuum and keep spilt material away from drains (SDS sections 6 and 12).
source: sds-bnnt
where: Sections 6 and 12
mitigations:
- text: Use the respirator class the SDS lists for the expected dust exposure (P95 or P1 for low exposure, P99 or P2 for high), with safety glasses and protective gloves (SDS section 8).
source: sds-bnnt
where: Section 8, Exposure controls
uses:
- application: radiation-shielding
device: Hydrogen-containing BNNT as a shield (modelled)
example: NASA Langley's Phase I modelling (OLTARIS, calculated, not measured) found that BN with 5% hydrogen gave better galactic cosmic ray protection than polyethylene in a 30 cm wall of the same thickness. The report also says BNNT alone does not beat the best current shields, except for secondary neutrons.
source: nasa-niac-2012
where: Summary, and Figure 1 caption
- application: radiation-shielding
device: Choice of shielding material (literature review)
example: A NASA Langley literature review slide lists boron, lithium and gadolinium as high thermal-neutron absorbers, and hydrogen as the best shield against galactic cosmic rays.
source: nasa-nifs-2020
where: Literature Review slide
- application: radiation-shielding
device: BNNT and BNNT polymer composites in a neutron exposure lab (ground)
example: NASA's overview summary reports excellent neutron radiation shielding effectiveness for BNNT. The slides we read give no numeric shielding result for BNNT.
source: nasa-overview
where: Summary slide; Neutron Radiation Shielding Study slides
- application: heat-shields
device: As-grown BNNT mat in an arc-jet test (ground)
example: NASA exposed a 25 mm diameter, 2 mm thick as-grown BNNT mat to a surface temperature of 1315 °C for 1 minute in its HYMETS arc-jet facility. The text we read gives FT-IR spectra before and after the test but no numeric pass or fail result.
source: nasa-overview
where: Hypersonic Materials Environmental Test System slides, sample and test conditions
supply:
- subject: Boron (feedstock for BNNT)
abundance: Crustal abundance not found in the sources read.
producers:
- country: Turkey
year: 2025
- country: Chile
year: 2025
- country: Bolivia
year: 2025
- country: Peru
year: 2025
- country: China
year: 2025
- country: Russia
year: 2025
- country: Argentina
year: 2025
- country: Germany
year: 2025
- country: United States
year: 2025
critical_lists:
- list: USGS 2025 List of Critical Minerals (boron added in the final list)
listed: true
- list: EU critical raw materials list (Regulation (EU) 2024/1252, as shown on the European Commission page)
listed: true
recycling: 'USGS: boron recycling is insignificant.'
substitutes:
- 'USGS: other materials can substitute for boron in detergents, enamels, insulation and soaps. No substitute for BNNT was found in the sources read.'
source: usgs-boron
where: 'World Production and Reserves table, 2025e, units as printed (Turkey, refined borates 1,500; Bolivia, ulexite 380; Chile, ulexite 300; United States withheld; world total not calculable per USGS). Import sources 2021 to 2024: Turkey 90%. EU list: the European Commission page lists Boron/Borate and says Turkey provides 99% of EU boron supply (ec-crm).'
media: []
documents:
- title: 'NASA Langley overview: Boron Nitride Nanotube (BNNT) and BNNT Composites'
type: report
url: https://ntrs.nasa.gov/api/citations/20200003735/downloads/20200003735.pdf
year: 2020
- title: 'NASA NIAC Phase I final report: Radiation Shielding Materials Containing Hydrogen, Boron, and Nitrogen'
type: report
url: https://ntrs.nasa.gov/api/citations/20160010096/downloads/20160010096.pdf
year: 2012
- title: 'Chen et al. 2017: Quantitative Characterization of Structural and Mechanical Properties of Boron Nitride Nanotubes in High Temperature Environments'
type: paper
url: https://pmc.ncbi.nlm.nih.gov/articles/PMC5595806/
year: 2017
- title: 'Review: Boron Nitride Nanotubes: Recent Advances in Their Synthesis, Functionalization, and Applications (Molecules)'
type: paper
url: https://pmc.ncbi.nlm.nih.gov/articles/PMC6272975/
year: 2016
- title: 'Safety data sheet: Boron Nitride Nanotubes (BNNT), supplier Raymor Industries Inc., print date 14 December 2021'
type: sds
url: https://nanointegris.com/wp-content/uploads/2022/01/5_SDS-BNNT_CANUTEC.pdf
year: 2021
- title: 'USGS Mineral Commodity Summaries 2026: Boron'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-boron.pdf
year: 2026
- title: 'NASA Langley 2020 Spring NIFS Symposium presentation: Radiation Study of Boron Nitride Nanotube (BNNT) and BNNT Composites'
type: report
url: https://ntrs.nasa.gov/api/citations/20205001454/downloads/Final%20Draft%20-%20Spring%202020%20NIFS%20Symposium%20Final%20Presentation%20Calista%20Lum%20sm%20revised.pdf
year: 2020
gaps:
- No measured thermal conductivity of BNNT, bulk or single tube, was found in the sources read. The only values are theoretical (NASA table, about 300 to 3000 W/mK).
- No flight, vacuum-exposure, thermal-cycling or radiation-exposure result on BNNT itself was found. The space evidence is modelling and ground testing.
- No measured neutron or galactic cosmic ray shielding number for BNNT was found in the sources read. The NIFS 2020 presentation reports indium-foil tests on boron carbide and aluminium 6061, not on BNNT.
- Humidity, UV and atomic-oxygen ageing of BNNT were not found in any source read.
- Crustal abundance of boron was not found in a source we could open.
- No BNNT producers, output or market shares were found. NASA's overview names BNNT LLC beside a cotton-like HTP-BNNT image and gives a 2014 plasma synthesis rate of 35 g per hour, which is a research figure, not a market figure.
- No nitrogen supply source was opened, so nitrogen is not covered under supply.
- No standard designations (UNS, EN, ASTM or trade names) for BNNT were found in a source we could open. The CAS number 10043-11-5 is the one the SDS prints for its boron nitride ingredient.
- The Australian assessment of BNNT (CA09938, June 2025), which treats BNNT as hazardous by analogy with carbon nanotubes, could not be opened because the server connection failed. It is not used.
- The PubChem record for boron nitride (CID 66227) was blocked by a browser check, so PubChem GHS data are not used.
- The Thibeault et al. 2015 MRS Bulletin review on nanomaterials for radiation shielding was not readable in full. Only the abstract and reference list were visible.
- 'Property names not in property-canon are used: band_gap, oxidation_resistance_temperature, oxidation_onset_temperature, air_survival_temperature, stability_in_air_temperature, neutron_capture_cross_section, median_outer_diameter, outer_diameter_range and typical_outer_diameter.'
- 'Sources disagree on several values and both are kept: 800 °C survival in the review against 850 °C (Chen et al.), 1.3 TPa and 1.8 TPa moduli, 2.5 nm and 2.9 nm median diameters, and 50 to 80 nm diameters for CVD tubes.'
- No image was licensed and fetched in this run, so media is empty.
sources:
nasa-overview:
title: 'Boron Nitride Nanotube (BNNT) and BNNT Composites: Overview'
id: NTRS 20200003735 (Park, Chu and Fay, NASA Langley)
url: https://ntrs.nasa.gov/api/citations/20200003735/downloads/20200003735.pdf
year: 2020
kind: report
nasa-nifs-2020:
title: Radiation Study of Boron Nitride Nanotube (BNNT) and BNNT Composites, 2020 Spring NIFS Symposium presentation
id: NTRS 20205001454 (Calista Lum)
url: https://ntrs.nasa.gov/api/citations/20205001454/downloads/Final%20Draft%20-%20Spring%202020%20NIFS%20Symposium%20Final%20Presentation%20Calista%20Lum%20sm%20revised.pdf
year: 2020
kind: report
nasa-niac-2012:
title: 'Radiation Shielding Materials Containing Hydrogen, Boron, and Nitrogen: NIAC Phase I final report'
id: NTRS 20160010096 (report dated 30 September 2012)
url: https://ntrs.nasa.gov/api/citations/20160010096/downloads/20160010096.pdf
year: 2012
kind: report
chen2017:
title: Quantitative Characterization of Structural and Mechanical Properties of Boron Nitride Nanotubes in High Temperature Environments
id: doi:10.1038/s41598-017-11795-9 (Scientific Reports 7, 1138)
url: https://pmc.ncbi.nlm.nih.gov/articles/PMC5595806/
year: 2017
kind: paper
molecules2016:
title: 'Boron Nitride Nanotubes: Recent Advances in Their Synthesis, Functionalization, and Applications'
id: Molecules 2016, 21(7), 922 (PMC6272975)
url: https://pmc.ncbi.nlm.nih.gov/articles/PMC6272975/
year: 2016
kind: paper
sds-bnnt:
title: 'Safety Data Sheet: Boron Nitride Nanotubes (BNNT), supplier Raymor Industries Inc.'
id: print date 14 December 2021, version 1 (hosted by NanoIntegris)
url: https://nanointegris.com/wp-content/uploads/2022/01/5_SDS-BNNT_CANUTEC.pdf
year: 2021
kind: datasheet
usgs-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
ec-crm:
title: Critical raw materials (European Commission page, Regulation (EU) 2024/1252)
url: https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en
year: 2024
kind: web
wiki-bnnt:
title: Boron nitride nanotube (Wikipedia, used for composition only)
url: https://en.wikipedia.org/wiki/Boron_nitride_nanotube
kind: web
nist-b:
title: 'NIST Atomic Weights and Isotopic Compositions: boron (Z = 5), standard atomic weight'
url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=B&all=all&ascii=html
kind: database
nist-n:
title: 'NIST Atomic Weights and Isotopic Compositions: nitrogen (Z = 7), standard atomic weight'
url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=N&all=all&ascii=html
kind: database
license: CC-BY-4.0
updated: '2026-11-01'
review:
status: draft
method: assistant
checked_values: 22
unreachable: 0
caveats: 10
note: Values read on 2026-11-01. NASA overview and NIAC report read as PDF text; SDS and USGS boron read as PDF text; the EU page read as HTML. The Chen et al. and Molecules review values were read through a summarising fetch of the HTML article, not the raw text.
story:
recipe:
line: Boron nitride nanotubes are made of boron and nitrogen in a one-to-one atom ratio. NASA's high-temperature, high-pressure method vaporises boron feedstock with a laser in nitrogen gas, with no catalyst, so boron and nitrogen are the only reactants.
parts:
- name: Boron
symbol: B
atoms: 1
atomic_weight: 10.806
role: Forms the tube wall with nitrogen. Its boron-10 isotope has a large thermal-neutron absorption cross section, which is why boron is used in neutron shielding.
source: nist-b
where: Standard atomic weight printed as an interval by NIST; the lower bound is entered
- name: Nitrogen
symbol: 'N'
atoms: 1
atomic_weight: 14.00643
role: Forms the tube wall with boron. Nitrogen has a larger neutron absorption cross section than carbon (NIAC report).
source: nist-n
where: Standard atomic weight printed as an interval by NIST; the lower bound is entered
risk_groups:
- title: For people
level: 2
verdict: Irritant dust; long-term toxicity unknown
lead: The supplier safety data sheet classes BNNT powder as an irritant. The toxicity of the nanotube form is not known.
points:
- label: The powder
line: The safety data sheet classes the BNNT product as an irritant for eyes, skin and airways, and gives no GHS classification. Its oral LD50 in rats is above 50 g/kg.
- label: Dust
line: Avoid breathing the dust. The SDS says frequent inhalation over a long period increases the risk of lung disease.
- label: Unknowns
line: The SDS says the acute and chronic toxicity of the nanotube component is not known and may differ with the number of walls.
- title: If a part overheats
level: 2
verdict: Oxidises above 900 °C in air
lead: These results come from heating tests on single tubes and microfibrils in air, not from field use.
points:
- label: Air at 850 °C
line: Individual tubes showed no morphology change after 10 minutes in air at 850 °C.
- label: Air at 900 °C
line: After 10 minutes at 900 °C a broken segment about 30 nm long appeared, which marks oxidation onset.
- label: Outgassing
line: NASA's NIAC report notes outgassing and flammability issues and recommends encapsulation.
- title: Handling and storage
points:
- label: Dust
line: Avoid dust formation. Use good ventilation or local exhaust, and clean spills with a HEPA-filter vacuum.
- label: Storage
line: Keep the container tightly closed in a cool, well-ventilated area.
why: 'Boron nitride nanotubes (BNNTs) are being studied by NASA Langley as a multifunctional material: stiff, heat-resistant tubes that also insulate electrically. NASA''s overview lists neutron shielding from their boron content, and a high service temperature above 800 °C, as benefits. NASA''s Phase I study tested by modelling whether hydrogen-containing BNNT could shield cosmic rays better than polyethylene at the same thickness.'
uses:
- where: Radiation shielding (modelled)
line: NASA's Phase I modelling found that BN with 5% hydrogen could shield galactic cosmic rays better than polyethylene of the same wall thickness. This is a calculated result, not a measurement.
- where: Heat test sample (ground)
line: NASA exposed an as-grown BNNT mat to a surface temperature of 1315 °C for 1 minute in an arc-jet test. The text we read gives no pass or fail number.
- where: Neutron shielding composites (ground)
line: NASA's overview reports excellent neutron shielding for BNNT and BNNT polymer composites in lab tests, but the slides we read give no numeric result.
can_do:
- label: Stiffness
benchmark: elastic_modulus
value: 760 to 960 GPa
line: Individual high-temperature, high-pressure tubes measured in NASA's in-situ SEM tests have an elastic modulus of 760 to 960 GPa. NASA's theoretical table gives 1.18 TPa as a theoretical nanotube value.
- label: Heat in air
benchmark: oxidation_onset_temperature
value: 900 °C onset
line: Single tubes survived 10 minutes in air at 850 °C with no change, and the first oxidation appeared at 900 °C (Chen et al. 2017).
- label: Density
benchmark: density
value: 0.27 to 0.3 g/cm3 (mat and disc forms)
line: As-grown mats and target discs of BNNT have densities of about 0.3 g/cm3 and 0.27 g/cm3. A NASA report gives 1.3 to 1.4 g/cm3 for the solid tube, without a cited test.
- label: Neutron capture
benchmark: neutron_capture_cross_section
value: 3835 barn
line: Boron-10 has a thermal-neutron absorption cross section of 3835 barns, as quoted in the NIAC report. That figure is for the isotope, not a measured BNNT shield.
compare: Relative to carbon nanotubes, NASA's theoretical table gives BNNTs a much higher oxidation resistance in air, stable to over 900 °C against 300 to 400 °C for carbon nanotubes, and a wide electrical band gap, where carbon nanotubes are metallic or semiconducting. The same table gives BNNTs a lower theoretical Young's modulus and thermal conductivity than carbon nanotubes. Measured values for single tubes are below the theoretical table values, so the table should not be read as a measured result.
compare_rows:
- label: Young's modulus, individual tube (measured)
benchmark: elastic_modulus
- label: Oxidation onset in air (measured, single tube)
benchmark: oxidation_onset_temperature
- label: Thermal conductivity (theoretical, nanotube)
benchmark: thermal_conductivity
handling:
- Treat the powder as an irritant. Avoid dust, use good ventilation or exhaust, and wear eye and skin protection.
- Keep containers closed in a cool, well-ventilated place. Clean spills with a HEPA-filter vacuum.
- In air, single tubes began to oxidise at 900 °C. Each temperature was held for 10 minutes, so these results do not cover longer exposure below that temperature.
good_for:
- Radiation shielding research. Hydrogen-containing BNNT was modelled to beat polyethylene at the same thickness (calculated, not measured).
- Heat-resistant insulating parts. Single tubes survived 850 °C in air for 10 minutes with no change.
watch_out:
- Most property values are theoretical, from one tube at a time, or from a single lab test. The sources disagree on several values, such as 800 °C against 850 °C for survival in air, and 1.3 TPa against 1.8 TPa for modulus.
- The SDS classes the powder as an irritant and says the nanotube toxicity is not known.
- The shielding figures are modelled. No measured BNNT shielding number was found in the sources read.
verdict: BNNT looks promising for heat-resistant, insulating and radiation-shielding parts, but the evidence is mostly theory, single-tube tests and modelling, so it is not yet a qualified material for spacecraft use.
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.
Updated