TUFI (toughened unipiece fibrous insulation) surface TUFI
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
Also known as TUFI
TUFI (toughened uni-piece fibrous insulation) is a rigid ceramic tile with a glass-based surface.
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.
Surface composition
20 %
Impact
0.8 joule
Coating density and porosity
0.66 g/cc
Recipe, share of the weight
- 77.5%Reactive glass frit
- SiB4 2.5%Silicon tetraboride
- MoSi2 20%Molybdenum disilicide
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
Risk at a glance
- People No data. No hazard data recorded
- If it fails Moderate. Impact damage to the surface coating
- Corrosion No data. No corrosion data recorded
Quick facts: TUFI
| Property | Value | Basis |
|---|---|---|
| Density | 0.66 g/cm³ | 1 sourced value |
What is the density of TUFI surface?
TUFI surface has a density of 0.66 g/cm³. The source and test conditions are listed in the properties table on this page.
What is TUFI surface used for?
Uses recorded in the sources include Black TUFI tiles on the orbiter underside; White TUFI tiles on the upper body flap and main engine area.
Why it exists
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.
Where it's used
Underside of the Space Shuttle (black TUFI)
Wikipedia says the black TUFI versions were used on the orbiter underside because they gave sufficient heat insulation, though they weighed more.
Upper body flap and main engine area (white TUFI)
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.
Recipe
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
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.
| Ingredient | Share of the weight | What it does |
|---|---|---|
| Reactive glass frit | 77.5% | The glass matrix. Per TPSX it is 5.75% boron oxide and 94.25% silica. |
| Silicon tetraboride SiB4 | 2.5% | A fluxing agent that helps the glass fuse during sintering, per the patent. |
| Molybdenum disilicide MoSi2 | 20% | The emittance agent. The patent says about 20 weight percent is needed to assure surface compatibility. |
Weight shares are as printed in the sources.
What it can do
Surface composition
20 %
measured
TPSX lists 20% molybdenum disilicide in the surface composition. The patent says about 20 weight percent is needed to assure surface compatibility.
Impact
0.8 joule
measured
In the patent's impact test, the porous coating showed no penetration into the substrate at 0.8 joule.
Coating density and porosity
0.66 g/cc
measured
The patent gives the porous coating a density of about 0.66 g/cc and a porosity of about 70%.
How it compares
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.
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.
| Measurement | TUFI |
|---|---|
| Capacity and energy | |
| Impact energy with no penetration into the substrate | 0.8 joule10 |
| Impact energy with no visible damage | 0.01 joule11 |
| Physical and electrical | |
| Density of the porous surface coating | 0.66 g/cc6 |
| Thickness of the porous surface coating | 0.5 mm8 |
| Weight of the preferred surface layerPreferred value stated in the patent description | 0.14 g/cm² |
| Temperature behavior | |
| Optimum sintering temperature of the coating | 1220 °C9 |
| Other measurements | |
| Silicon tetraboride (SiB4) share of the surface composition | 2.5 %1 |
| Reactive glass frit share of the surface composition | 77.5 %2 |
| Boron oxide (B2O3) share of the reactive glass frit | 5.75 %3 |
| Silica (SiO2) share of the reactive glass frit | 94.25 %4 |
| Molybdenum disilicide (MoSi2) share of the surface composition | 20 %5 |
| Porosity of the porous surface coating | 70 %7 |
| Sintering time at the preferred temperaturePreferred value stated in the patent description | 90 minutes |
Why choose it, and why not
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 for
- 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.
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.
Technical details
For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.
Other names and standards
The same grade under other systems, as datasheets and standards print them. Each code was checked against the page it comes from.
| System | Codes |
|---|---|
| Trade name | TUFI (TPSX material name 'TUFI Composite Surface') |
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Silicon tetraboride (SiB4) share of the surface composition | Composition figure printed on the TPSX property page | basis share of the surface composition as printed by TPSX; the patent gives the same figure in weight percentcomposition TUFI surface | — |
| 2 | Reactive glass frit share of the surface composition | Composition figure printed on the TPSX property page | basis share of the surface composition as printed by TPSX; the patent gives the same figure in weight percentcomposition TUFI surface | — |
| 3 | Boron oxide (B2O3) share of the reactive glass frit | Composition figure printed on the TPSX property page | 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 | — |
| 4 | Silica (SiO2) share of the reactive glass frit | Composition figure printed on the TPSX property page | basis share of the frit, printed in parentheses after the 77.5% term | — |
| 5 | Molybdenum disilicide (MoSi2) share of the surface composition | Composition figure printed on the TPSX property page; the patent describes the same constituent as the emittance agent | basis share of the surface composition as printed by TPSX; the patent states about 20 weight percent molybdenum disilicidecomposition TUFI surface | — |
| 6 | Density of the porous surface coating | Approximate value stated in the patent description | layer porous surface coating 26 of the patent (the invention), not the earlier reactive glass coatingprinted as about 0.66g/cc | — |
| 7 | Porosity of the porous surface coating | Approximate value stated in the patent description | layer porous surface coating 26 of the patentprinted as about 70% | — |
| 8 | Thickness of the porous surface coating | Value stated in the patent description, where it is compared with the earlier coating | layer porous surface coating 26 of the patentprinted as 0.5mm | — |
| 9 | Optimum sintering temperature of the coating | Value stated in the patent as the optimum sintering temperature | process fusion of the coating slurry on the substrateprinted as 1220° C. | — |
| 10 | Impact energy with no penetration into the substrate | Impact test described in the patent (Example I); a laboratory test, not a flight result | coating porous surface coating 26 of the patenttest impact test with a hemispherically shaped head, as described in Example I of the patentobservation no penetration into the substrate | — |
| 11 | Impact energy with no visible damage | Impact test described in the patent (Example I); a laboratory test, not a flight result | coating porous surface coating 26 of the patenttest same impact test as the 0.8 joule row (Example I)observation no damage is visible | — |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
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.
- The tile
- The sources read describe composition, the coating and test results. They say nothing about hazards to people.
- Silica
- PubChem gives the primary hazards of silica as Not Classified.
On the vehicle
These are design limits and test results, not incident reports.
- Underside
- The black version gave sufficient heat insulation for the orbiter underside but weighed more, which restricted its use to specific areas (Wikipedia).
- Upper body flap
- The white version conducted more heat, which limited it to the upper body flap and main engine area (Wikipedia).
- Impact
- The patent reports no penetration into the substrate at 0.8 joule for the porous coating, and no visible damage at 0.01 joule.
Handling and storage
No handling or storage rule for TUFI was found in the sources read.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Impact damage to the surface coatingmoderate severity | Impact by a hemispherical head in the patent impact test (Example I)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. |
| Higher heat conduction in the white versionmoderate severity | Use on the orbiter's upper surfacesWikipedia says the white versions conducted more heat, which limited their use to the orbiter's upper body flap and main engine area. |
| Extra weight of the black versionlow severity | Use on the orbiter undersideWikipedia says the black versions had sufficient heat insulation for the underside but greater weight, which restricted their use to specific areas. |
Supply and geography
How common the raw materials are and where they come from.
Molybdenum (from MoSi2)
- Top producers (2025)
- China 37.3%, Chile 16.2%, United States 15.4%, Peru 15%, Mexico 6.5%
- Recycling
- USGS: molybdenum is recycled as a component of catalysts, ferrous scrap and superalloy scrap.
Silicon (silicon metal; silica as the raw feedstock)
USGS: the source of the silicon is silica in various natural forms, such as quartzite.
- Top producers (2025)
- China 87%, Brazil 3.9%, Norway 2.8%
- Critical mineral lists
- US: listed
- Recycling
- USGS: recycling of silicon is insignificant.
Boron (from B2O3 and SiB4)
- Top producers (2025)
- Turkey
- Critical mineral lists
- US: listed
- Recycling
- USGS: recycling of boron is insignificant.
Documents
Datasheets, safety data sheets, papers and standards you can open.
| Document | Type | Year |
|---|---|---|
| NASA Ames TPSX record: TUFI Composite Surface (Material id 8) | database | 2006 |
| NASA Ames TPSX record: TUFI/AETB-8 Diffusion Layer (Material id 9) | database | 2006 |
| US Patent 5,079,082: Toughened uni-piece fibrous insulation (NASA) | paper | 1992 |
| PubChem: Silica (silicon dioxide) compound record, GHS and hazards | database | 2026 |
| USGS Mineral Commodity Summaries 2026: Molybdenum | report | 2026 |
| USGS Mineral Commodity Summaries 2026: Silicon | report | 2026 |
| USGS Mineral Commodity Summaries 2026: Boron | report | 2026 |
Full record
The complete spore, as stored. Free to reuse under CC-BY-4.0. Images keep the licence shown with each one.
Show the full YAML
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)
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.
| # | Source | Type | Year | Used for |
|---|---|---|---|---|
| TUFI Composite Surface, NASA Ames Thermal Protection Materials database record (Material id 8) | database | 2006 | 6 values | |
| TUFI/AETB-8 Diffusion Layer, NASA Ames Thermal Protection Materials database record (Material id 9) | database | 2006 | 0 values | |
| Space Shuttle thermal protection system (Wikipedia article) | web | 2026 | 4 values | |
| Toughened uni-piece fibrous insulation, US Patent 5,079,082 (Leiser, Smith, Churchward, Katvala; assignee NASA) | web | 1992 | 9 values | |
| PubChem compound record, Silica (silicon dioxide) | database | 2026 | 1 value | |
| Mineral Commodity Summaries 2026, Molybdenum | report | 2026 | 1 value | |
| Mineral Commodity Summaries 2026, Silicon | report | 2026 | 1 value | |
| Mineral Commodity Summaries 2026, Boron | report | 2026 | 1 value |
Updated