spore: profile id: tufi-tile-surface spore_version: 0.2 family: silica name: TUFI (toughened unipiece fibrous insulation) surface abbreviation: TUFI role: Reusable rigid ceramic tile surface on the Space Shuttle orbiter (black version on the underside, white version on the upper body flap) category: thermal-protection type: reusable-tiles summary: | TUFI (toughened uni-piece fibrous insulation) is a rigid ceramic tile with a glass-based surface. NASA's TPSX record lists its surface composition as 77.5% reactive glass frit, 2.5% SiB4 and 20% MoSi2. A NASA patent with the same title describes a porous surface coating of about 0.66g/cc density and about 70% porosity, which showed no penetration into the substrate at 0.8 joule of impact. best_for: Impact-tolerant reusable insulation where higher heat conduction is acceptable (Wikipedia says the white version was limited to the upper body flap and main engine area) weakest_at: Heat conduction in the white version, which limited its use, and no strength or thermal test values for TUFI in the sources read identity: formula: 'Silica-glass composite per TPSX: 77.5% reactive glass frit (containing 5.75% boron oxide and 94.25% silica), 2.5% silicon tetraboride and 20% molybdenum disilicide' designations: - system: Trade name code: TUFI note: TPSX material name 'TUFI Composite Surface' source: tpsx-tufi where: Material name field source: tpsx-tufi where: Material name, Composition and Category fields (TPSX Material id 8) tags: applications: - heat-shields - thermal-control properties: - benchmark: silicon_tetraboride_content label: Silicon tetraboride (SiB4) share of the surface composition value: 2.5 unit: '%' scope: material conditions: basis: share of the surface composition as printed by TPSX; the patent gives the same figure in weight percent composition: TUFI surface method: Composition figure printed on the TPSX property page status: ground source: tpsx-tufi where: Composition field, third term - benchmark: reactive_glass_frit_content label: Reactive glass frit share of the surface composition value: 77.5 unit: '%' scope: material conditions: basis: share of the surface composition as printed by TPSX; the patent gives the same figure in weight percent composition: TUFI surface method: Composition figure printed on the TPSX property page status: ground source: tpsx-tufi where: Composition field, first term - benchmark: boron_oxide_in_frit_content label: Boron oxide (B2O3) share of the reactive glass frit value: 5.75 unit: '%' scope: material conditions: basis: share of the frit, printed in parentheses after the 77.5% term; the patent also gives 5.75 weight percent boron oxide in the preferred frit method: Composition figure printed on the TPSX property page status: ground source: tpsx-tufi where: Composition field, parentheses after the frit term - benchmark: silica_in_frit_content label: Silica (SiO2) share of the reactive glass frit value: 94.25 unit: '%' scope: material conditions: basis: share of the frit, printed in parentheses after the 77.5% term method: Composition figure printed on the TPSX property page status: ground source: tpsx-tufi where: Composition field, parentheses after the frit term - benchmark: molybdenum_disilicide_content label: Molybdenum disilicide (MoSi2) share of the surface composition value: 20 unit: '%' scope: material conditions: basis: share of the surface composition as printed by TPSX; the patent states about 20 weight percent molybdenum disilicide composition: TUFI surface method: Composition figure printed on the TPSX property page; the patent describes the same constituent as the emittance agent status: ground source: tpsx-tufi where: Composition field, last term - benchmark: density label: Density of the porous surface coating value: 0.66 unit: g/cc scope: material conditions: layer: porous surface coating 26 of the patent (the invention), not the earlier reactive glass coating printed_as: about 0.66g/cc method: Approximate value stated in the patent description status: ground source: us-patent-5079082 where: Description, paragraph comparing coating 26 with coating 14 - benchmark: porosity label: Porosity of the porous surface coating value: 70 unit: '%' scope: material conditions: layer: porous surface coating 26 of the patent printed_as: about 70% method: Approximate value stated in the patent description status: ground source: us-patent-5079082 where: Description, sentence on the porosity of coating 26 - benchmark: coating_thickness label: Thickness of the porous surface coating value: 0.5 unit: mm scope: material conditions: layer: porous surface coating 26 of the patent printed_as: 0.5mm method: Value stated in the patent description, where it is compared with the earlier coating status: ground source: us-patent-5079082 where: Description, sentence comparing coating 26 with coating 14 - benchmark: areal_density label: Weight of the preferred surface layer value: 0.14 unit: g/cm2 scope: material conditions: layer: preferred surface layer 26 of the patent printed_as: 0.14g/cm2 method: Preferred value stated in the patent description status: ground source: us-patent-5079082 where: Description, preferred weight of the surface layer - benchmark: sintering_temperature label: Optimum sintering temperature of the coating value: 1220 unit: °C scope: material conditions: process: fusion of the coating slurry on the substrate printed_as: 1220° C. method: Value stated in the patent as the optimum sintering temperature status: ground source: us-patent-5079082 where: Description, sintering paragraph - benchmark: sintering_time label: Sintering time at the preferred temperature value: 90 unit: minutes scope: material conditions: temperature: preferred sintering temperature of 1220 degrees C printed_as: 90 minutes method: Preferred value stated in the patent description status: ground source: us-patent-5079082 where: Description, sintering paragraph - benchmark: impact_energy label: Impact energy with no penetration into the substrate value: 0.8 unit: joule scope: material conditions: coating: porous surface coating 26 of the patent test: impact test with a hemispherically shaped head, as described in Example I of the patent observation: no penetration into the substrate method: Impact test described in the patent (Example I); a laboratory test, not a flight result status: ground source: us-patent-5079082 where: Example I (impact testing) - benchmark: impact_energy label: Impact energy with no visible damage value: 0.01 unit: joule scope: material conditions: coating: porous surface coating 26 of the patent test: same impact test as the 0.8 joule row (Example I) observation: no damage is visible method: Impact test described in the patent (Example I); a laboratory test, not a flight result status: ground source: us-patent-5079082 where: Example I (impact observation) corrosion: [] risks: hazards: - text: PubChem's record for silica (silicon dioxide) gives its primary hazards as Not Classified. The record covers silica in general, not the TUFI tile or its coating, and no safety data sheet for TUFI was found. ghs: [] source: pubchem-silica where: Safety and Hazards, Primary Hazards field of the compound record failure_risks: - mode: Impact damage to the surface coating trigger: Impact by a hemispherical head in the patent impact test (Example I) consequence: The patent reports no penetration into the substrate at 0.8 joule and no visible damage at 0.01 joule for the porous coating. It gives no energy at which the coating itself fails. severity: moderate source: us-patent-5079082 where: Example I (impact testing) - mode: Higher heat conduction in the white version trigger: Use on the orbiter's upper surfaces consequence: Wikipedia says the white versions conducted more heat, which limited their use to the orbiter's upper body flap and main engine area. severity: moderate source: wiki-tps where: Tile types section - mode: Extra weight of the black version trigger: Use on the orbiter underside consequence: Wikipedia says the black versions had sufficient heat insulation for the underside but greater weight, which restricted their use to specific areas. severity: low source: wiki-tps where: Tile types section side_effects: [] handling: [] mitigations: [] uses: - application: heat-shields device: Black TUFI tiles on the orbiter underside example: Wikipedia says the black TUFI versions were used on the orbiter underside, where their heat insulation was sufficient, though they weighed more. source: wiki-tps where: Tile types section - application: thermal-control device: White TUFI tiles on the upper body flap and main engine area example: Wikipedia says the white TUFI versions were more impact resistant than other tiles but conducted more heat, which limited them to the upper body flap and main engine area. source: wiki-tps where: Tile types section supply: - subject: Molybdenum (from MoSi2) producers: - country: China share_percent: 37.3 year: 2025 - country: Chile share_percent: 16.2 year: 2025 - country: United States share_percent: 15.4 year: 2025 - country: Peru share_percent: 15 year: 2025 - country: Mexico share_percent: 6.5 year: 2025 critical_lists: [] recycling: 'USGS: molybdenum is recycled as a component of catalysts, ferrous scrap and superalloy scrap.' substitutes: [] source: usgs-mcs2026-molybdenum where: World Mine Production and Reserves table, mine production 2025e. Shares are calculated by Space Mushroom against the 260,000 t world total. The USGS text says China, Chile, the United States, Peru and Mexico accounted for 90% of global production in 2025. - subject: Silicon (silicon metal; silica as the raw feedstock) abundance: 'USGS: the source of the silicon is silica in various natural forms, such as quartzite.' producers: - country: China share_percent: 87 year: 2025 - country: Brazil share_percent: 3.9 year: 2025 - country: Norway share_percent: 2.8 year: 2025 critical_lists: - list: USGS 2025 Final List of Critical Minerals (silicon added, per the Mineral Commodity Summary) listed: true recycling: 'USGS: recycling of silicon is insignificant.' substitutes: [] source: usgs-mcs2026-silicon where: World Mine Production table, silicon metal, 2025 (world total 4,600 thousand t, rounded; shares calculated by Space Mushroom). Critical list status from the Mineral Commodity Summary introduction. - subject: Boron (from B2O3 and SiB4) producers: - country: Turkey year: 2025 critical_lists: - list: USGS 2025 Final List of Critical Minerals (boron added, per the Mineral Commodity Summary) listed: true recycling: 'USGS: recycling of boron is insignificant.' substitutes: [] source: usgs-mcs2026-boron where: 'Import Sources, all forms, 2021 to 2024: Turkey 90%. World Production table, 2025e: Turkey refined borates 1,500 thousand t. The world total is printed as XX, so no share is calculated.' documents: - title: 'NASA Ames TPSX record: TUFI Composite Surface (Material id 8)' type: database url: https://tpsx.arc.nasa.gov/Material?id=8 year: 2006 - title: 'NASA Ames TPSX record: TUFI/AETB-8 Diffusion Layer (Material id 9)' type: database url: https://tpsx.arc.nasa.gov/Material?id=9 year: 2006 - title: 'US Patent 5,079,082: Toughened uni-piece fibrous insulation (NASA)' type: paper url: https://patents.google.com/patent/US5079082A/en year: 1992 - title: 'PubChem: Silica (silicon dioxide) compound record, GHS and hazards' type: database url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/24261/JSON year: 2026 - title: 'USGS Mineral Commodity Summaries 2026: Molybdenum' type: report url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf year: 2026 - title: 'USGS Mineral Commodity Summaries 2026: Silicon' type: report url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silicon.pdf year: 2026 - title: 'USGS Mineral Commodity Summaries 2026: Boron' type: report url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-boron.pdf year: 2026 gaps: - TPSX prints density, thermal conductivity, specific heat, emissivity, use-temperature limits, recombination coefficients and their uncertainties in exponent form. Those values cannot be matched to the page text, so they are left out. The standard TUFI rows for density, conductivity, emissivity and temperature limit are therefore missing. - 'Strength: no tensile, flexural or modulus value for TUFI was found in the sources read, and the patent gives no strength values.' - 'Thermal conductivity and emissivity: the patent gives thermal conductivity only as graphs and emissivity only as a description, so no numeric value was read.' - 'Hazards: no safety data sheet or GHS classification for TUFI, molybdenum disilicide or silicon tetraboride was read. The silica record covers silica in general.' - 'Ageing and corrosion: no oxidation, ageing or cycle data for TUFI were found in the sources read.' - 'Handling and storage: no handling or storage rule for TUFI was found in the sources read.' - 'Flight history: the sources give no failure record or flight count for TUFI.' - 'Tile counts: the Wikipedia counts of tiles are for other tile types, so no TUFI tile count is stated.' - 'Manufacturer: TPSX names Boeing and United Space Alliance, while the patent names NASA as assignee. The conflict is not resolved.' - 'Link between patent and flight tile: the patent describes a porous surface coating on a substrate of a related tile type. The match to flight TUFI rests on the shared title and the matching composition in TPSX. The patent''s substrate examples are not used as TUFI values.' - 'Critical-mineral status for molybdenum: the USGS chapter read does not state a critical-list status, so none is recorded.' - Atomic weights for the recipe parts were not printed by any source read in this run, so they are left out. - Supply shares are calculated from the USGS tables (see the where fields), not printed by USGS. No boron share is calculated because the world total is not printed. - Benchmark names for the composition shares, coating thickness, areal density, sintering time and impact energy are not in the canonical property list, so short snake_case names are used. - 'Media: no image files were fetched, so the media section is left out.' - 'Grant date: the patent date is taken from the Google Patents page; no second source was checked.' license: CC-BY-4.0 updated: '2026-11-01' review: status: draft method: assistant checked_values: 13 unreachable: 0 caveats: 2 note: Read by an AI assistant on 2026-11-01 from TPSX Material ids 8 and 9, the Wikipedia Space Shuttle TPS article, the Google Patents page for US 5,079,082, and the USGS Mineral Commodity Summaries 2026 for molybdenum, silicon and boron. TPSX values in exponent form are left out. story: recipe: line: 'TUFI is a silica-glass tile. Its surface is built from three ingredients by weight: 77.5% reactive glass frit, 2.5% silicon tetraboride and 20% molybdenum disilicide (TPSX). The frit itself is 5.75% boron oxide and 94.25% silica. The patent describes the coating as a slurry applied in several passes and sintered at 1220 °C for 90 minutes.' parts: - name: Reactive glass frit share_percent: 77.5 role: The glass matrix. Per TPSX it is 5.75% boron oxide and 94.25% silica. source: tpsx-tufi where: Composition field - name: Silicon tetraboride symbol: SiB4 share_percent: 2.5 role: A fluxing agent that helps the glass fuse during sintering, per the patent. source: tpsx-tufi where: Composition field - name: Molybdenum disilicide symbol: MoSi2 share_percent: 20 role: The emittance agent. The patent says about 20 weight percent is needed to assure surface compatibility. source: tpsx-tufi where: Composition field risk_groups: - title: For people verdict: No hazard classification for TUFI lead: No safety data sheet for TUFI was found. PubChem's silica record gives its primary hazards as Not Classified, but that record covers silica in general. points: - label: The tile line: The sources read describe composition, the coating and test results. They say nothing about hazards to people. - label: Silica line: PubChem gives the primary hazards of silica as Not Classified. - title: On the vehicle lead: These are design limits and test results, not incident reports. points: - label: Underside line: The black version gave sufficient heat insulation for the orbiter underside but weighed more, which restricted its use to specific areas (Wikipedia). - label: Upper body flap line: The white version conducted more heat, which limited it to the upper body flap and main engine area (Wikipedia). - label: Impact line: The patent reports no penetration into the substrate at 0.8 joule for the porous coating, and no visible damage at 0.01 joule. - title: Handling and storage lead: No handling or storage rule for TUFI was found in the sources read. points: [] why: 'TUFI (toughened unipiece fibrous insulation) is a rigid ceramic tile for reusable thermal protection. Wikipedia describes it as a stronger, tougher tile introduced later in the Shuttle programme, and says it was more impact resistant than other tiles. The trade is heat insulation for impact tolerance: the white versions resisted impact better but conducted more heat. TPSX lists the surface as 77.5% reactive glass frit, 2.5% silicon tetraboride and 20% molybdenum disilicide. The NASA patent with the same title describes the coating''s density, porosity and impact results.' uses: - where: Underside of the Space Shuttle (black TUFI) line: Wikipedia says the black TUFI versions were used on the orbiter underside because they gave sufficient heat insulation, though they weighed more. - where: Upper body flap and main engine area (white TUFI) line: The white version was more impact resistant but conducted more heat, which limited its use to the upper body flap and main engine area, according to Wikipedia. can_do: - label: Surface composition benchmark: molybdenum_disilicide_content line: TPSX lists 20% molybdenum disilicide in the surface composition. The patent says about 20 weight percent is needed to assure surface compatibility. - label: Impact benchmark: impact_energy line: In the patent's impact test, the porous coating showed no penetration into the substrate at 0.8 joule. - label: Coating density and porosity benchmark: density line: The patent gives the porous coating a density of about 0.66 g/cc and a porosity of about 70%. compare: Within the sources read, TUFI is compared with the earlier reactive glass coating only in the patent. The patent says the porous coating is thicker and lower in density than that earlier coating, and that the porous coating is more resistant to impact than the earlier coating. No strength or thermal-conductivity value for TUFI is recorded here, so a full comparison with other tiles is not possible. The table below lists the three TUFI values the sources support for a side-by-side view. compare_rows: - label: Coating density benchmark: density - label: Porosity benchmark: porosity - label: Molybdenum disilicide share benchmark: molybdenum_disilicide_content handling: - No handling or storage rule for TUFI was found in the sources read. - Plan for impact. The patent test shows no penetration at 0.8 joule, but it does not give a damage threshold for the tile in service. good_for: - Impact tolerance. Wikipedia says the white TUFI versions were more impact resistant than other tiles. - Surface emittance. TPSX includes 20% molybdenum disilicide in the surface, which the patent describes as the emittance agent. watch_out: - Heat conduction. The white version conducted more heat, which limited its use (Wikipedia). - No strength, thermal conductivity or use-temperature value for TUFI is in this profile, because the TPSX values are in exponent form and were left out. - The patent describes a coating and lab impact tests, not flight hardware. verdict: TUFI trades heat conduction for impact tolerance, as the white versions show. The sources read support its composition and coating figures, but not the strength or thermal values needed for a full design comparison. sources: tpsx-tufi: title: TUFI Composite Surface, NASA Ames Thermal Protection Materials database record (Material id 8) id: TPSX Material id=8; last modified 2001-10-01 per the page url: https://tpsx.arc.nasa.gov/Material?id=8 year: 2006 kind: database license: public domain (NASA) tpsx-tufi-diffusion: title: TUFI/AETB-8 Diffusion Layer, NASA Ames Thermal Protection Materials database record (Material id 9) id: TPSX Material id=9; last modified 2001-10-01 per the page url: https://tpsx.arc.nasa.gov/Material?id=9 year: 2006 kind: database license: public domain (NASA) wiki-tps: title: Space Shuttle thermal protection system (Wikipedia article) id: Wikipedia article, accessed 2026-11-01 url: https://en.wikipedia.org/wiki/Space_Shuttle_thermal_protection_system year: 2026 kind: web license: CC BY-SA 4.0 (Wikipedia text, cited not reproduced) us-patent-5079082: title: Toughened uni-piece fibrous insulation, US Patent 5,079,082 (Leiser, Smith, Churchward, Katvala; assignee NASA) id: US 5,079,082 A url: https://patents.google.com/patent/US5079082A/en year: 1992 kind: web license: public domain (US patent text) pubchem-silica: title: PubChem compound record, Silica (silicon dioxide) id: CID 24261 url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/24261/JSON year: 2026 kind: database license: public domain (NCBI) usgs-mcs2026-molybdenum: title: Mineral Commodity Summaries 2026, Molybdenum id: USGS MCS 2026, February 2026 url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf year: 2026 kind: report license: public domain (USGS) usgs-mcs2026-silicon: title: Mineral Commodity Summaries 2026, Silicon id: USGS MCS 2026, February 2026 url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silicon.pdf year: 2026 kind: report license: public domain (USGS) 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)