spore: profile id: nextel-312 spore_version: 0.2 family: ceramic-fibres name: Nextel 312 (alumina-boria-silica ceramic fibre and fabric) role: Alumina-silica-boria ceramic fibre, woven into fabric for high-temperature insulation and as a layer in debris shields category: textiles type: beta-cloth summary: Nextel 312 is an alumina-silica-boria ceramic fibre. Goodfellow prints its composition as Al2O3 62, SiO2 24 and B2O3 14, with a density of 2.7 g/cm3 and a tensile strength of 1700 MPa. The supplier gives an upper continuous use temperature of 1200-1400 °C. The International Space Station (ISS) article reports five Stuffed Whipple shields, which pair Nextel 312 fabric with Kevlar, installed in August 2012 against micrometeoroids and orbital debris. best_for: Debris-shield and high-temperature insulation layers where the supplier's 1200-1400 °C continuous use limit and 1700 MPa tensile strength matter weakest_at: Alkali and concentrated acid exposure, rated Poor-Fair and Fair by the supplier, and no in-orbit lifetime data in the sources we hold identity: formula: Al2O3 62 / SiO2 24 / B2O3 14 (alumina-silica-boria fibre; percentages as printed by Goodfellow, basis not stated) source: gf-312 where: Product name and Composition line on the Goodfellow Nextel 312 page; the same composition is printed in the Goodfellow technical data sheet designations: - system: Trade name code: Nextel 312 source: gf-312 where: Grade line on the Goodfellow Nextel 312 page tags: environments: - low-earth-orbit stresses: - hypervelocity-impact - high-temperature applications: - habitats-and-suits - thermal-control - structures properties: - benchmark: density label: Density, Nextel 312 fibre value: 2.7 unit: g/cm3 scope: material conditions: form: fibre grade: Nextel 312, Al2O3 62 / SiO2 24 / B2O3 14 method: Value printed on the Goodfellow product page and repeated in its technical data sheet; no test method printed status: ground source: gf-312 where: Physical Properties table, Density row - benchmark: ultimate_tensile_strength label: Tensile strength, Nextel 312 fibre value: 1700 unit: MPa scope: material conditions: form: fibre test_temperature: not printed test_method: not printed method: Printed on the Goodfellow product page (Mechanical Properties); no test standard printed status: ground source: gf-312 where: Mechanical Properties table, Tensile strength row - benchmark: elastic_modulus label: Tensile modulus, Nextel 312 fibre value: 140 unit: GPa scope: material conditions: form: fibre test_temperature: not printed method: Printed on the Goodfellow product page (Mechanical Properties); no test standard printed status: ground source: gf-312 where: Mechanical Properties table, Tensile modulus row - benchmark: max_service_temp label: Upper continuous use temperature, Nextel 312 fibre value: 1200 value_high: 1400 bound: range unit: °C scope: material conditions: form: fibre basis: upper continuous use temperature as printed; no time, atmosphere or load given method: Range printed on the Goodfellow product page (Thermal Properties) status: ground source: gf-312 where: Thermal Properties table, Upper continuous use temperature row - benchmark: sublimation_point label: Sublimation point, Nextel 312 fibre value: 1800 unit: °C scope: material conditions: form: fibre note: sublimation point as printed; not a melting point method: Printed on the Goodfellow product page (Thermal Properties); the name is not in the canonical list, see gaps status: ground source: gf-312 where: Thermal Properties table, Sublimation point row - benchmark: specific_heat label: Specific heat, Nextel 312 fibre value: 1100 unit: J K-1 kg-1 scope: material conditions: form: fibre temperature: 25 °C method: Printed on the Goodfellow product page (Thermal Properties) as 1100 at 25 °C status: ground source: gf-312 where: Thermal Properties table, Specific heat row - benchmark: cte label: Coefficient of thermal expansion, Nextel 312 fibre value: 3 unit: x10-6 K-1 scope: material conditions: form: fibre temperature_range: 20 to 1000 °C note: printed as x10-6 K-1, equal to ppm/K method: Printed on the Goodfellow product page (Thermal Properties) status: ground source: gf-312 where: Thermal Properties table, Coefficient of thermal expansion row - benchmark: refractive_index label: Refractive index, Nextel 312 fibre value: 1.57 unit: '-' scope: material conditions: form: fibre condition: none printed on the page method: Printed on the Goodfellow product page (Physical Properties) status: ground source: gf-312 where: Physical Properties table, Refractive index row - benchmark: dielectric_constant label: Dielectric constant, Nextel 312 fibre value: 5.2 unit: '-' scope: material conditions: form: fibre frequency: 9.4 GHz method: Printed on the Goodfellow product page (Electrical Properties) as 5.2 at 9.4 GHz status: ground source: gf-312 where: Electrical Properties table, Dielectric constant row - benchmark: density label: Density, Nextel 440 (variant grade, for comparison) value: 3.05 unit: g/cm3 scope: material conditions: grade: Nextel 440, Al2O3 70 / SiO2 28 / B2O3 2 (a separate grade, not an alias of Nextel 312) form: fibre method: Printed on the Goodfellow Nextel 440 product page; no condition printed status: ground source: gf-440 where: Physical Properties table, Density row - benchmark: ultimate_tensile_strength label: Tensile strength, Nextel 440 (variant grade, for comparison) value: 2000 unit: MPa scope: material conditions: grade: Nextel 440, Al2O3 70 / SiO2 28 / B2O3 2 (a separate grade) test_temperature: not printed method: Printed on the Goodfellow Nextel 440 product page (Mechanical Properties) status: ground source: gf-440 where: Mechanical Properties table, Tensile strength row - benchmark: elastic_modulus label: Tensile modulus, Nextel 440 (variant grade, for comparison) value: 185 unit: GPa scope: material conditions: grade: Nextel 440, Al2O3 70 / SiO2 28 / B2O3 2 (a separate grade) test_temperature: not printed method: Printed on the Goodfellow Nextel 440 product page (Mechanical Properties) status: ground source: gf-440 where: Mechanical Properties table, Tensile modulus row - benchmark: max_service_temp label: Upper continuous use temperature, Nextel 440 (variant grade, for comparison) value: 1350 value_high: 1650 bound: range unit: °C scope: material conditions: grade: Nextel 440, Al2O3 70 / SiO2 28 / B2O3 2 (a separate grade) basis: as printed; no time, atmosphere or load given method: Range printed on the Goodfellow Nextel 440 product page (Thermal Properties) status: ground source: gf-440 where: Thermal Properties table, Upper continuous use temperature row - benchmark: specific_heat label: Specific heat, Nextel 440 (variant grade, for comparison) value: 1000 unit: J K-1 kg-1 scope: material conditions: grade: Nextel 440 (a separate grade) temperature: 500 °C method: Printed on the Goodfellow Nextel 440 product page (Thermal Properties) as 1000 at 500 °C status: ground source: gf-440 where: Thermal Properties table, Specific heat row - benchmark: cte label: Coefficient of thermal expansion, Nextel 440 (variant grade, for comparison) value: 5 unit: x10-6 K-1 scope: material conditions: grade: Nextel 440 (a separate grade) temperature_range: 20 to 1000 °C note: printed as x10-6 K-1, equal to ppm/K method: Printed on the Goodfellow Nextel 440 product page (Thermal Properties) status: ground source: gf-440 where: Thermal Properties table, Coefficient of thermal expansion row corrosion: - environment: Concentrated acids headline: Rated Fair in concentrated acids by the supplier. effect: 'Goodfellow rates Nextel 312 Fair in concentrated acids. The rating is qualitative: the page gives no acid, concentration, temperature or exposure time.' rating: unknown conditions: basis: qualitative supplier rating; no test printed source: gf-312 where: Chemical Resistance table, Acids - concentrated row - environment: Dilute acids headline: Rated Good in dilute acids by the supplier. effect: Goodfellow rates Nextel 312 Good in dilute acids. As with the other ratings, no test conditions are printed. rating: unknown conditions: basis: qualitative supplier rating; no test printed source: gf-312 where: Chemical Resistance table, Acids - dilute row - environment: Alkalis headline: Rated Poor-Fair in alkalis, the lowest of the supplier's ratings for this fibre. effect: Goodfellow rates Nextel 312 Poor-Fair in alkalis. This is the weakest chemical rating on the page, so alkaline cleaning or exposure needs a check against the supplier's data before use. rating: unknown conditions: basis: qualitative supplier rating; no test printed source: gf-312 where: Chemical Resistance table, Alkalis row - environment: Metals headline: Rated Good with metals by the supplier. effect: Goodfellow rates contact with metals as Good. The page does not name which metals or give a test. rating: unknown conditions: basis: qualitative supplier rating; metals not named source: gf-312 where: Chemical Resistance table, Metals row risks: hazards: - text: '3M safety data sheet for Nextel Ceramic Fiber 312 with Organic Sizing (version 52.03, issued 08/17/26), Section 2.1: ''Not classified as hazardous according to OSHA Hazard Communication Standard, 29 CFR 1910.1200.'' Section 2.2 gives no signal word and no pictograms. This is the sized 3M product; it is not confirmed to be the same material as the Goodfellow fibre.' ghs: [] source: 3m-nextel312-sds where: Section 2 (2.1 Hazard classification and 2.2 Label elements) - text: '3M safety data sheet, Section 11.1: ''Due to their large size (7-15 microns in diameter), Nextel(TM) Ceramic Fibers do not meet the definition of respirable as defined by WHO convention and ECHA.'' 3M adds that ''Because Nextel fibers are considered non-respirable, they are not expected to pose a cancer risk.''' ghs: [] source: 3m-nextel312-sds where: Section 11.1, Additional Health Effects - text: PubChem's record for silica (CID 24261, a constituent of the fibre) lists several ECHA C&L notification sets that do not agree. One set reports 'Not Classified', with 'Reported as not meeting GHS hazard criteria by 7724 of 9127 companies'. Another, with signal word Warning, lists H315, H319 and H335. A third, with signal word Danger, lists H350, H372 and H373. PubChem does not say which silica form each set covers, so these statements describe silica in general and not this fibre. ghs: [] source: pubchem-silica where: Hazards Identification, GHS Classification (CID 24261) - text: PubChem's record for corundum (aluminium oxide, CID 14769, a constituent of the fibre) gives 'Not Classified' as reported by '1 of 1 companies'. A separate notification set with signal word Danger lists H319 'Causes serious eye irritation', H335 'May cause respiratory irritation' and H372 'Causes damage to organs through prolonged or repeated exposure'. These describe alumina in general, not this fibre. ghs: [] source: pubchem-corundum where: Hazards Identification, GHS Classification (CID 14769) failure_risks: - mode: Attack by alkalis trigger: Exposure to alkaline media, rated Poor-Fair by the supplier consequence: The supplier rates the fibre Poor-Fair in alkalis; no strength loss or test result is printed. severity: moderate source: gf-312 where: Chemical Resistance table, Alkalis row - mode: Attack by concentrated acids trigger: Exposure to concentrated acids, rated Fair by the supplier consequence: The supplier rates the fibre Fair in concentrated acids; no strength loss or test result is printed. severity: low source: gf-312 where: Chemical Resistance table, Acids - concentrated row side_effects: [] handling: - text: '3M safety data sheet for the sized variant, Section 7.1: avoid breathing dust created by cutting, sanding, grinding or machining.' source: 3m-nextel312-sds where: Section 7.1, Precautions for safe handling - text: '3M safety data sheet, Section 8.1: ACGIH lists borate compounds, inorganic, inhalable fraction (CAS 12788-79-3) with TWA(inhalable fraction):2 mg/m3 and STEL(inhalable fraction):6 mg/m3, and comments ''A4: Not class. as human carcin''.' source: 3m-nextel312-sds where: Section 8.1, Occupational exposure limits table - text: '3M safety data sheet, Section 8.2.2: safety glasses with side shields are recommended, no protective gloves are required and respiratory protection is not required.' source: 3m-nextel312-sds where: Section 8.2.2, Personal protective equipment mitigations: [] uses: - application: habitats-and-suits device: Stuffed Whipple micrometeoroid and debris shields on the International Space Station example: The ISS article reports five 1-inch-thick shields installed in August 2012, each pairing Nextel 312 fabric with Kevlar behind an aluminium bumper, and gives a hypervelocity range of 3-18 kilometres per second. source: ceramics-iss where: Article body, Stuffed Whipple shield description and installation report (article dated 28 August 2012) - application: thermal-control device: Furnace linings and seals example: The Goodfellow technical data sheet describes Nextel 312 as flexible, high-temperature ceramic insulation for furnace linings and seals. source: gf-312-tds where: Introduction paragraph of the technical data sheet - application: structures device: Composite reinforcement example: The Goodfellow technical data sheet lists composite reinforcement as a use for Nextel 312 fibre. source: gf-312-tds where: Introduction paragraph of the technical data sheet supply: - subject: Boron (as B2O3) abundance: Not stated in the USGS boron chapter read for this profile production_note: 'USGS 2025 world production table: Turkey refined borates 1,500 thousand t (2025e), 1,800 thousand t (2024); world total not printed (XX). Turkey holds 950,000 thousand t of reserves. US imports of all forms came from Turkey 90%, Bolivia 6% and other 4% (2021-24).' producers: [] critical_lists: - list: USGS 2025 List of Critical Minerals (boron added in the final 2025 list) listed: true recycling: 'USGS boron chapter: recycling is ''Insignificant.''' substitutes: - 'USGS: substitution for boron is possible in detergents, enamels, insulation and soaps. Insulation substitutes it names are cellulose, foams and mineral wools.' source: usgs-mcs2026-boron where: Domestic production and use; Salient Statistics; Import Sources (2021-24); World Production and Reserves table; critical minerals paragraph; Recycling; Substitutes - subject: Aluminium (metal; the fibre uses alumina, so smelter data is a proxy) abundance: Not stated in the USGS aluminum chapter read for this profile production_note: USGS smelter production table, world total (rounded) 74,000 thousand t in 2025e; China 45,000, India 4,200, Russia 3,900, Canada 3,300, United Arab Emirates 2,700. The US imported aluminium mainly from Canada (56%, 2021-24). producers: - country: China share_percent: 60.8 year: 2025 - country: India share_percent: 5.7 year: 2025 - country: Russia share_percent: 5.3 year: 2025 - country: Canada share_percent: 4.5 year: 2025 - country: United Arab Emirates share_percent: 3.6 year: 2025 critical_lists: [] recycling: 'USGS: about 3.6 million tons of aluminum were recovered from purchased scrap in the United States in 2025.' substitutes: - 'USGS: composites can substitute for aluminum in aircraft fuselages and wings.' source: usgs-mcs2026-aluminum where: Smelter production table, 2025e (shares calculated by Space Mushroom against the 74,000 thousand t world total); Import Sources (2021-24); Recycling; Substitutes - subject: Silicon (as SiO2) abundance: Not stated in the sources read producers: [] critical_lists: - list: USGS 2025 List of Critical Minerals (silicon added in the final 2025 list) listed: true recycling: Not read for silicon in this run. substitutes: [] source: usgs-mcs2026-boron where: Critical minerals paragraph of the boron chapter, which names the silicon addition to the 2025 list media: [] documents: - title: 'Goodfellow technical data sheet: Nextel 312 Alumina-Silica-Boria Fiber (SKU 1000002802-group)' type: datasheet url: https://www.goodfellow.com/usa/technical_data/pdf/download?sku=1000002802-group - title: 'Goodfellow product page: Nextel 312 Alumina-Silica-Boria Fiber' type: datasheet url: https://www.goodfellow.com/usa/nextel-312-alumina-silica-boria-fibre-group - title: 'Goodfellow product page: Nextel 440 Alumina-Silica-Boria Fiber' type: datasheet url: https://www.goodfellow.com/usa/nextel-440-alumina-silica-boria-fibre-group - title: 'USGS Mineral Commodity Summaries 2026: Boron' type: report url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-boron.pdf year: 2026 - title: 'USGS Mineral Commodity Summaries 2026: Aluminum' type: report url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf year: 2026 - title: '3M Nextel Ceramic Fiber 312 with Organic Sizing: Safety Data Sheet (version 52.03, issued 08/17/26)' type: sds url: https://cdmsweb.3m.com/ingredientcommunication/file/Media/rMevoVj9NRk= - title: 'PubChem CID 24261 Silica: GHS Classification' type: database url: https://pubchem.ncbi.nlm.nih.gov/compound/24261 - title: 'PubChem CID 14769 Corundum: GHS Classification' type: database url: https://pubchem.ncbi.nlm.nih.gov/compound/14769 gaps: - No in-orbit lifetime, atomic-oxygen, ultraviolet, radiation or thermal-cycling result for Nextel 312 was found in the sources read. The ISS article gives the installation only. - 3M product datasheets returned HTTP 403, so 3M's own property figures for the fabric were not read. The 3M safety data sheet was read from a different 3M host, and it covers the sized variant only; its density range and melting point were not added as properties because they describe that variant. The ISS article quotes 3M only in passing. - The AF62 designation was not found on any fetched page, so it is not listed under designations. - The ISS article gives no areal density, no Kevlar or aluminium layer thickness and no shield test specification. It does not say how many layers or what gap sits between them. - 'No safety data sheet for the Goodfellow fibre itself was read: the Goodfellow SDS link is a placeholder. The 3M SDS read covers the sized variant only. PubChem entries were read for silica and corundum, which are constituents; the PubChem record for boron trioxide (CID 518682) carried no GHS hazard codes in the data read. No NIOSH entry was read, and side effects and mitigations remain empty.' - Sublimation point, apparent porosity and water absorption use names outside the canonical property list (sublimation_point, apparent_porosity, water_absorption_saturation). - The upper continuous use temperature gives no time, atmosphere or load, and no strength-at-temperature or creep data were found. - 'Tensile strength and modulus: the test temperature, gauge length and test method are not printed.' - Chemical resistance ratings are qualitative. No numeric corrosion or weight-loss data were found. - The Goodfellow technical data sheet prints supplier product code AL62-FB-000112. This is a supplier code, not a designation, so it is not listed. - Aluminium critical-list status and abundance are not in the USGS aluminum chapter read. The EU critical raw materials list was not checked for boron or silicon. Alumina and bauxite are in a separate USGS chapter that was not read. - The 1995 International Journal of Impact Engineering paper cited by the ISS article was not opened. - The Wikipedia Nextel article covers a US telecom company, not the fibre, so it was not used. - No abbreviation and no licensed image were found for Nextel 312, so media is empty. sources: gf-312: title: Nextel 312 Alumina-Silica-Boria Fiber (Goodfellow product page) id: Goodfellow grade Nextel 312, commodity Ceramics url: https://www.goodfellow.com/usa/nextel-312-alumina-silica-boria-fibre-group kind: datasheet license: supplier page, cited not reproduced gf-312-tds: title: Nextel 312 Alumina-Silica-Boria Fiber technical data sheet (Goodfellow PDF) id: SKU 1000002802-group; product code AL62-FB-000112 url: https://www.goodfellow.com/usa/technical_data/pdf/download?sku=1000002802-group kind: datasheet license: supplier document, cited not reproduced gf-440: title: Nextel 440 Alumina-Silica-Boria Fiber (Goodfellow product page) id: Goodfellow grade Nextel 440, commodity Ceramics url: https://www.goodfellow.com/usa/nextel-440-alumina-silica-boria-fibre-group kind: datasheet license: supplier page, cited not reproduced ceramics-iss: title: Nextel ceramic fabric stars in recent International Space Station walk (Ceramic Tech Today) id: American Ceramic Society, article dated 28 August 2012 url: https://ceramics.org/ceramic-tech-today/nextel-ceramic-fabric-stars-in-recent-international-space-station-walk/ year: 2012 kind: web license: cited, not reproduced wiki-whipple: title: Whipple shield (Wikipedia) id: en.wikipedia.org, Whipple_shield url: https://en.wikipedia.org/wiki/Whipple_shield kind: web license: CC BY-SA 4.0 (Wikipedia text) 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) usgs-mcs2026-aluminum: title: 'Mineral Commodity Summaries 2026: Aluminum' id: USGS MCS 2026, February 2026 url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf year: 2026 kind: report license: public domain (USGS) 3m-nextel312-sds: title: 3M Nextel Ceramic Fiber 312 with Organic Sizing, Safety Data Sheet id: 3M document group 10-4844-6, version 52.03, issue date 08/17/26 url: https://cdmsweb.3m.com/ingredientcommunication/file/Media/rMevoVj9NRk= year: 2026 kind: datasheet license: supplier document, cited not reproduced pubchem-silica: title: Silica (PubChem CID 24261), GHS Classification id: PubChem CID 24261, record title Silica url: https://pubchem.ncbi.nlm.nih.gov/compound/24261 kind: database license: PubChem record, cited not reproduced pubchem-corundum: title: Corundum (PubChem CID 14769), GHS Classification id: PubChem CID 14769, record title Corundum url: https://pubchem.ncbi.nlm.nih.gov/compound/14769 kind: database license: PubChem record, cited not reproduced license: CC-BY-4.0 updated: '2026-11-01' review: status: draft method: assistant checked_values: 15 unreachable: 1 caveats: 3 note: Written by an AI assistant on 2026-11-01 from pages fetched in that run. The 3M datasheet returned HTTP 403, but a 3M safety data sheet for the sized variant was read from a second 3M host; hazards and two PubChem constituent records were added on 2026-11-01 and no property values were changed. Values are as printed on the Goodfellow pages and datasheet; the ISS article was read through the fetch summary and not re-checked against the original page text. story: recipe: line: Nextel 312 is an alumina-silica-boria fibre. Goodfellow prints its composition as Al2O3 62, SiO2 24 and B2O3 14. The page does not say whether these shares are by mass or by moles, and it does not describe how the fibre is spun or fired. parts: - name: Aluminium oxide (alumina) symbol: Al2O3 share: '62' role: The largest printed constituent and the backbone of the fibre. The share is printed without a stated basis. - name: Silicon dioxide (silica) symbol: SiO2 share: '24' role: The second printed constituent. - name: Boron oxide (boria) symbol: B2O3 share: '14' role: The third printed constituent. The boria gives the grade its name. risk_groups: - title: For people level: 0 verdict: Not classified as hazardous (3M sized variant) lead: The Goodfellow safety data sheet link is a placeholder. The 3M safety data sheet for the sized variant does not classify the product as hazardous under OSHA HCS. points: - label: Fibre line: Handle the fibre with care. The 3M sized-variant safety data sheet advises avoiding breathing dust from cutting, sanding, grinding or machining, and it states the product is not classified as hazardous. No hazard statement for the Goodfellow fibre itself was found. - title: In a debris strike lead: The ISS article describes the Stuffed Whipple shield as a protective layer. It reports no penetration or failure data. points: - label: Shield layer line: Five shields were installed in August 2012. Each pairs Nextel 312 fabric with Kevlar behind an aluminium bumper. The article gives a hypervelocity range of 3-18 kilometres per second. - title: Chemical exposure lead: The supplier rates the fibre by chemical group, and all of its ratings are qualitative. points: - label: Alkalis line: Rated Poor-Fair, the weakest rating on the page. - label: Concentrated acids line: Rated Fair. Dilute acids are rated Good. why: Nextel 312 is an alumina-silica-boria ceramic fibre sold by Goodfellow. Its composition is printed as Al2O3 62, SiO2 24 and B2O3 14. The supplier gives a density of 2.7 g/cm3, a tensile strength of 1700 MPa and a tensile modulus of 140 GPa, with an upper continuous use temperature of 1200-1400 °C. The International Space Station (ISS) carries Stuffed Whipple shields that use Nextel 312 fabric with Kevlar. A Whipple shield is a shield with filler between its rigid layers, and a stuffed Whipple shield adds that filler. The shield design is the reason the fibre is in the ISS story. uses: - where: Debris shields on the ISS line: The Ceramic Tech Today article reports five 1-inch-thick shields installed in August 2012. Each pairs Nextel 312 fabric with Kevlar, behind an aluminium bumper, to form a stuffed Whipple shield against micrometeoroids and orbital debris. - where: Furnace linings and seals line: The Goodfellow technical data sheet describes Nextel 312 as flexible, high-temperature ceramic insulation for furnace linings and seals. - where: Composite reinforcement line: The same data sheet lists composite reinforcement as a use for the fibre. can_do: - label: Density benchmark: density value: 2.7 g/cm3 line: The supplier gives a density of 2.7 g/cm3 for Nextel 312 fibre. The variant Nextel 440 is denser at 3.05 g/cm3. - label: Strength benchmark: ultimate_tensile_strength value: 1700 MPa line: Goodfellow prints a tensile strength of 1700 MPa and a tensile modulus of 140 GPa for the fibre. The test conditions are not printed. - label: Temperature benchmark: max_service_temp value: 1200-1400 °C line: The upper continuous use temperature is printed as 1200-1400 °C, and the sublimation point as 1800 °C. The page gives no time, atmosphere or load for the continuous-use figure. - label: Electrical benchmark: dielectric_constant value: 5.2 at 9.4 GHz line: The dielectric constant is printed as 5.2 at 9.4 GHz. The page gives no temperature for this value. compare: Within Goodfellow's own pair of grades, Nextel 312 is lighter and weaker than Nextel 440. Its printed density is 2.7 g/cm3 against 3.05 g/cm3, its tensile strength 1700 MPa against 2000 MPa, and its tensile modulus 140 GPa against 185 GPa. Its upper continuous use temperature is printed as 1200-1400 °C against 1350-1650 °C for Nextel 440. Nextel 440 has a higher alumina share (Al2O3 70), so the two are separate grades and not aliases. No comparison with Kevlar, 3M test data or other shield materials is made, because those values were not read in this run. compare_rows: - label: Density benchmark: density - label: Tensile strength benchmark: ultimate_tensile_strength - label: Upper continuous use temperature benchmark: max_service_temp handling: - The 3M safety data sheet for the sized variant advises avoiding breathing dust from cutting, sanding, grinding or machining. The Goodfellow safety data sheet link is a placeholder, so this is not confirmed for the Goodfellow fibre. - Use the usual care for a fine ceramic fibre, and wear safety glasses with side shields, as the 3M sheet recommends. - The supplier rates the fibre Poor-Fair in alkalis, so keep it away from alkaline media unless a check has been made. good_for: - Debris and micrometeoroid shields. The ISS article reports five Stuffed Whipple shields that use Nextel 312 with Kevlar. - High-temperature insulation. The data sheet describes furnace linings and seals as uses, with a continuous use limit of 1200-1400 °C. watch_out: - 'Alkalis: rated Poor-Fair by the supplier.' - No in-orbit lifetime data were found. The ISS article reports the installation, not its performance over time. - All chemical ratings are qualitative, with no test conditions printed. verdict: Nextel 312 has a documented role in ISS debris shields and a clear supplier data set for density, strength and continuous use temperature. Its in-orbit lifetime and 3M test data are not in the sources we hold. The only safety data sheet read is 3M's for a sized variant, which is not classified as hazardous under OSHA HCS.