Aluminosilicate glass Aluminosilicate

spore: profile
id: aluminosilicate-glass
spore_version: 0.2
family: glass-and-composites
name: Aluminosilicate glass
abbreviation: Aluminosilicate
role: display and cover glass
category: glasses-optics
type: borosilicate
summary: |
  Aluminosilicate glass is a silica network with alumina and alkali or alkaline-earth oxides added. Corning's EAGLE XG, an alkaline-earth boro-aluminosilicate, has a density of 2.38 g/cc, a strain point of 669 C and a working point of 1293 C (Corning MIE 301, 2006). Corning's Gorilla Glass 2, an alkali aluminosilicate, has a compressive stress capability of 1000 MPa at a 40 um depth of layer after chemical strengthening (Corning product sheet, 2012). Chemical strengthening swaps sodium ions in the surface for potassium ions from a hot salt bath. NASA tested Corning Code 1723 aluminosilicate window glass for Apollo and found no refractive-index change at the third decimal after 30 days of space-equivalent irradiation (NASA, 1968).
best_for: Thin cover and display glass that is chemically strengthened, where hardness and a high softening point matter more than cost
weakest_at: 'Cost and processing: EAGLE XG has a working point of 1293 C, and strengthening needs a molten potassium salt bath (EAGLE XG data, Zeng et al. 2016)'
identity:
  formula: 'Silica-alumina network with alkali or alkaline-earth oxides (model alkali aluminosilicate: 0.25 Na2O, 0.08 Al2O3, 0.67 SiO2 in mole fraction; EAGLE XG is an alkaline-earth boro-aluminosilicate)'
  source: wikipedia-gorilla-glass
  where: 'Infobox, composition row (alkali-aluminosilicate: SiO2, Al2O3, Na2O, MgO). The model composition is from the Experimental section of Zeng et al. 2016.'
  designations:
    - system: Trade name
      code: EAGLE XG
      source: eagle-xg-mie301
      where: Title block, trademark note
    - system: Trade name
      code: Xensation
      source: schott-xensation
      where: Technical details page, Mechanical properties table header
tags:
  environments:
    - cislunar
  stresses: []
  applications:
    - electronics-and-chips
    - solar-arrays
    - habitats-and-suits
properties:
  - benchmark: density
    label: Density (EAGLE XG)
    value: 2.38
    unit: g/cc
    scope: material
    conditions:
      product: EAGLE XG
      temperature: 20 C
    method: Printed as 2.38 g/cc (20 C, 68 F) in the Density row of the mechanical table.
    status: ground
    source: eagle-xg-mie301
    where: Mechanical table, Density row
  - benchmark: elastic_modulus
    label: Young's modulus (EAGLE XG)
    value: 73.6
    unit: GPa
    scope: material
    conditions:
      product: EAGLE XG
    method: Printed as 73.6 GPa (10.7 x 10^6 psi) in the Young's Modulus row.
    status: ground
    source: eagle-xg-mie301
    where: Mechanical table, Young's Modulus row
  - benchmark: shear_modulus
    label: Shear modulus (EAGLE XG)
    value: 30.1
    unit: GPa
    scope: material
    conditions:
      product: EAGLE XG
    method: Printed as 30.1 GPa in the Shear Modulus row.
    status: ground
    source: eagle-xg-mie301
    where: Mechanical table, Shear Modulus row
  - benchmark: poissons_ratio
    label: Poisson's ratio (EAGLE XG)
    value: 0.23
    unit: '-'
    scope: material
    conditions:
      product: EAGLE XG
    method: Printed as 0.23 in the Poisson's Ratio row.
    status: ground
    source: eagle-xg-mie301
    where: Mechanical table, Poisson's Ratio row
  - benchmark: cte
    label: Linear thermal expansion, 0 to 300 C (EAGLE XG)
    value: 31.7
    unit: x10^-7/C
    scope: material
    conditions:
      product: EAGLE XG
      temperature_range: 0 to 300 C
    method: Printed as 31.7 x 10^-7/C (0 to 300 C) and 17.7 x 10^-7/F. The metric value is used, unconverted.
    status: ground
    source: eagle-xg-mie301
    where: Thermal Expansion row, 0 to 300 C
  - benchmark: cte
    label: Linear thermal expansion, room temperature to setting point (EAGLE XG)
    value: 35.5
    unit: x10^-7/C
    scope: material
    conditions:
      product: EAGLE XG
      temperature_range: 25 to 675 C
    method: Printed as 35.5 x 10^-7/C (25 to 675 C) in the Room Temperature To Setting Point row.
    status: ground
    source: eagle-xg-mie301
    where: Thermal Expansion, Room Temperature To Setting Point row
  - benchmark: annealing_point
    label: Annealing point, 10^13 poise (EAGLE XG)
    value: 722
    unit: C
    scope: material
    conditions:
      product: EAGLE XG
      viscosity: 10^13 poise
    method: Printed as 722 C at 1013 poises in the Viscosity block.
    status: ground
    source: eagle-xg-mie301
    where: Viscosity block, Annealing Point row
  - benchmark: strain_point
    label: Strain point, 10^14.5 poise (EAGLE XG)
    value: 669
    unit: C
    scope: material
    conditions:
      product: EAGLE XG
      viscosity: 10^14.5 poise
    method: Printed as 669 C at 1014.5 poises in the Viscosity block.
    status: ground
    source: eagle-xg-mie301
    where: Viscosity block, Strain Point row
  - benchmark: softening_point
    label: Softening point, 10^7.6 poise (EAGLE XG)
    value: 971
    unit: C
    scope: material
    conditions:
      product: EAGLE XG
      viscosity: 10^7.6 poise
    method: Printed as 971 C at 107.6 poises in the Viscosity block.
    status: ground
    source: eagle-xg-mie301
    where: Viscosity block, Softening Point row
  - benchmark: working_point
    label: Working point, 10^4 poise (EAGLE XG)
    value: 1293
    unit: C
    scope: material
    conditions:
      product: EAGLE XG
      viscosity: 10^4 poise
    method: Printed as 1293 C at 10^4 poises in the Viscosity block.
    status: ground
    source: eagle-xg-mie301
    where: Viscosity block, Working Point row
  - benchmark: dielectric_constant
    label: Dielectric constant (EAGLE XG)
    value: 5.27
    unit: '-'
    scope: material
    conditions:
      product: EAGLE XG
      frequency: 1 kHz
      temperature: 20 C
    method: Printed as 5.27 at 20 C, 1 kHz.
    status: ground
    source: eagle-xg-mie301
    where: Electrical table, Dielectric Constant row
  - benchmark: dissipation_factor
    label: Loss tangent (EAGLE XG)
    value: 0.3
    unit: '%'
    scope: material
    conditions:
      product: EAGLE XG
      frequency: 1 kHz
      temperature: 20 C
    method: Printed as Loss Tangent 0.30% at 20 C, 1 kHz. The printed percent is kept.
    status: ground
    source: eagle-xg-mie301
    where: Electrical table, Loss Tangent row
  - benchmark: refractive_index
    label: Refractive index (EAGLE XG)
    value: 1.5099
    unit: '-'
    scope: material
    conditions:
      product: EAGLE XG
      wavelength: 589.3 nm
    method: Printed as 1.5099 at 589.3 nm in the Optical table.
    status: ground
    source: eagle-xg-mie301
    where: Optical table, 589.3 nm row
  - benchmark: specific_heat
    label: Specific heat (EAGLE XG)
    value: 0.768
    unit: J/(g.K)
    scope: material
    conditions:
      product: EAGLE XG
      temperature: 23 C
    method: Printed as 0.768 J/(gm-K) at 23 C. The printed unit is kept.
    status: ground
    source: eagle-xg-mie301
    where: Thermal table, Specific Heat column, 23 C row
  - benchmark: thermal_conductivity
    label: Thermal conductivity, calculated (EAGLE XG)
    value: 0.0109
    unit: W/cm.K
    scope: material
    conditions:
      product: EAGLE XG
      temperature: 23 C
    method: MIE 301 states that thermal conductivity is calculated as diffusivity times specific heat times density. Printed as 0.0109 W/cm-K at 23 C; the printed unit is kept.
    status: calculated
    source: eagle-xg-mie301
    where: Thermal table, Thermal Conductivity column, 23 C row
  - benchmark: log10_volume_resistivity
    label: Log10 volume resistivity (EAGLE XG)
    value: 12.9
    unit: log10 ohm-cm
    scope: material
    conditions:
      product: EAGLE XG
      temperature: 250 C
    method: Printed as 12.9 log10 ohm-cm at 250 C (482 F). Not a canonical name.
    status: ground
    source: eagle-xg-mie301
    where: Electrical block, Log10 Volume Resistivity row, 250 C
  - benchmark: density
    label: Density (Gorilla Glass 2)
    value: 2.42
    unit: g/cm3
    scope: material
    conditions:
      product: Gorilla Glass 2
      basis: no temperature printed on the sheet
    method: Printed as 2.42 g/cm3 in the Density row of the Properties block.
    status: ground
    source: gorilla-glass-2
    where: Properties block, Density row
  - benchmark: elastic_modulus
    label: Young's modulus (Gorilla Glass 2)
    value: 71.5
    unit: GPa
    scope: material
    conditions:
      product: Gorilla Glass 2
    method: Printed as 71.5 GPa in the Young's Modulus row.
    status: ground
    source: gorilla-glass-2
    where: Properties block, Young's Modulus row
  - benchmark: shear_modulus
    label: Shear modulus (Gorilla Glass 2)
    value: 29.6
    unit: GPa
    scope: material
    conditions:
      product: Gorilla Glass 2
    method: Printed as 29.6 GPa in the Shear Modulus row.
    status: ground
    source: gorilla-glass-2
    where: Properties block, Shear Modulus row
  - benchmark: poissons_ratio
    label: Poisson's ratio (Gorilla Glass 2)
    value: 0.21
    unit: '-'
    scope: material
    conditions:
      product: Gorilla Glass 2
    method: Printed as 0.21 in the Poisson's Ratio row.
    status: ground
    source: gorilla-glass-2
    where: Properties block, Poisson's Ratio row
  - benchmark: cte
    label: Coefficient of expansion, 0 to 300 C (Gorilla Glass 2)
    value: 81.4
    unit: x10^-7/C
    scope: material
    conditions:
      product: Gorilla Glass 2
      temperature_range: 0 to 300 C
    method: Printed as 81.4 x 10^-7/C (0 to 300 C).
    status: ground
    source: gorilla-glass-2
    where: Properties block, Coefficient of Expansion row
  - benchmark: annealing_point
    label: Annealing point, 10^13 poise (Gorilla Glass 2)
    value: 653
    unit: C
    scope: material
    conditions:
      product: Gorilla Glass 2
      viscosity: 10^13.2 poise
    method: Printed as 653 C at 1013.2 poises in the Viscosity block.
    status: ground
    source: gorilla-glass-2
    where: Viscosity block, Annealing Point row
  - benchmark: strain_point
    label: Strain point, 10^14.7 poise (Gorilla Glass 2)
    value: 599
    unit: C
    scope: material
    conditions:
      product: Gorilla Glass 2
      viscosity: 10^14.7 poise
    method: Printed as 599 C at 1014.7 poises in the Viscosity block.
    status: ground
    source: gorilla-glass-2
    where: Viscosity block, Strain Point row
  - benchmark: softening_point
    label: Softening point, 10^7.6 poise (Gorilla Glass 2)
    value: 895
    unit: C
    scope: material
    conditions:
      product: Gorilla Glass 2
      viscosity: 10^7.6 poise
    method: Printed as 895 C at 107.6 poises in the Viscosity block.
    status: ground
    source: gorilla-glass-2
    where: Viscosity block, Softening Point row
  - benchmark: vickers_hardness
    label: Vickers hardness, unstrengthened (Gorilla Glass 2)
    value: 534
    unit: kgf/mm2
    scope: material
    conditions:
      product: Gorilla Glass 2
      state: unstrengthened
      load: 200 g
    method: Printed as 534 kgf/mm2 at 200 g load, unstrengthened.
    status: ground
    source: gorilla-glass-2
    where: Properties block, Vickers Hardness row, unstrengthened line
  - benchmark: vickers_hardness
    label: Vickers hardness, strengthened (Gorilla Glass 2)
    value: 649
    unit: kgf/mm2
    scope: material
    conditions:
      product: Gorilla Glass 2
      state: chemically strengthened
      load: 200 g
    method: Printed as 649 kgf/mm2 at 200 g load, strengthened.
    status: ground
    source: gorilla-glass-2
    where: Properties block, Vickers Hardness row, strengthened line
  - benchmark: fracture_toughness
    label: Fracture toughness (Gorilla Glass 2)
    value: 0.68
    unit: MPa m0.5
    scope: material
    conditions:
      product: Gorilla Glass 2
    method: Printed as 0.68 MPa m0.5 in the Fracture Toughness row. Not a canonical name.
    status: ground
    source: gorilla-glass-2
    where: Properties block, Fracture Toughness row
  - benchmark: refractive_index
    label: Refractive index, core glass (Gorilla Glass 2)
    value: 1.5
    unit: '-'
    scope: material
    conditions:
      product: Gorilla Glass 2
      wavelength: 590 nm
    method: Printed as 1.50 for the core glass at 590 nm. The compression layer is 1.51 on the same line.
    status: ground
    source: gorilla-glass-2
    where: Optical block, Refractive Index, Core Glass row
  - benchmark: dielectric_constant
    label: Dielectric constant (Gorilla Glass 2)
    value: 7.24
    unit: '-'
    scope: material
    conditions:
      product: Gorilla Glass 2
      frequency: 50 MHz
    method: Printed as 7.24 at 50 MHz in the Electrical table.
    status: ground
    source: gorilla-glass-2
    where: Electrical table, 50 MHz row
  - benchmark: dissipation_factor
    label: Loss tangent (Gorilla Glass 2)
    value: 0.03
    unit: '-'
    scope: material
    conditions:
      product: Gorilla Glass 2
      frequency: 50 MHz
      bound: printed as less than 0.03
    method: Printed as less than 0.03 at 50 MHz. The value is the printed upper bound.
    status: ground
    source: gorilla-glass-2
    where: Electrical table, Loss Tangent column, 50 MHz row
  - benchmark: compressive_stress_capability
    label: Compressive stress capability (Gorilla Glass 2)
    value: 1000
    unit: MPa
    scope: material
    conditions:
      product: Gorilla Glass 2
      depth_of_layer: 40 um
    method: Printed as 1000 MPa at 40 um DOL. The sheet also prints 950 MPa at 50 um DOL. Not a canonical name.
    status: ground
    source: gorilla-glass-2
    where: Chemical Strengthening block, Compressive Stress Capability row
  - benchmark: depth_of_layer
    label: Depth of layer capability (Gorilla Glass 2)
    value: 50
    unit: um
    scope: material
    conditions:
      product: Gorilla Glass 2
      basis: capability printed on the sheet
    method: Printed as 50 um in the Depth of Layer Capability row. Not a canonical name.
    status: ground
    source: gorilla-glass-2
    where: Chemical Strengthening block, Depth of Layer Capability row
  - benchmark: vickers_hardness
    label: Vickers hardness, untreated, 1 to 7 mol% P2O5 (model glass)
    value: 4.8
    value_high: 5.1
    unit: GPa
    scope: material
    conditions:
      product: Model glass xP2O5-(100-x)(0.25Na2O-0.08Al2O3-0.67SiO2)
      state: untreated
      load: 0.98 N, 10 s
    method: Text says the hardness of the untreated glasses decreases from about 5.1 to 4.8 GPa as P2O5 rises from 1 to 7 mol%. Read as a range.
    status: ground
    source: zeng-2016
    where: Results, Vickers hardness paragraph (page 4)
  - benchmark: vickers_hardness
    label: Vickers hardness after ion exchange, 400 C 6 h (model glass)
    value: 5.5
    value_high: 6.1
    unit: GPa
    scope: material
    conditions:
      product: Model glass xP2O5-(100-x)(0.25Na2O-0.08Al2O3-0.67SiO2)
      state: ion exchanged in molten KNO3 at 400 C for 6 h
      load: 0.98 N, 10 s
    method: Text says the hardness of the ion-exchanged glasses increases from 5.5 to 6.1 GPa with rising P2O5.
    status: ground
    source: zeng-2016
    where: Results, Vickers hardness paragraph (page 4)
  - benchmark: density
    label: Density (SCHOTT Xensation Core)
    value: 2.38
    unit: g/cm3
    scope: material
    conditions:
      variant: Xensation Core
      basis: typical measured values, unstrengthened glass
    method: Printed as 2.38 g/cm3 in the Density row, Core column.
    status: ground
    source: schott-xensation
    where: Mechanical properties table, Density row, Core column
  - benchmark: density
    label: Density (SCHOTT Xensation Up)
    value: 2.48
    unit: g/cm3
    scope: material
    conditions:
      variant: Xensation Up
      basis: typical measured values, unstrengthened glass
    method: Printed as 2.48 g/cm3 in the Density row, Up column.
    status: ground
    source: schott-xensation
    where: Mechanical properties table, Density row, Up column
  - benchmark: elastic_modulus
    label: Young's modulus (SCHOTT Xensation Core)
    value: 78
    unit: kN/mm2
    scope: material
    conditions:
      variant: Xensation Core
      basis: typical measured values, unstrengthened glass
    method: Printed as 78 kN/mm2 in the Young's modulus row, Core column. The printed unit is kept.
    status: ground
    source: schott-xensation
    where: Mechanical properties table, Young's modulus row, Core column
  - benchmark: shear_modulus
    label: Shear modulus (SCHOTT Xensation Core)
    value: 32
    unit: kN/mm2
    scope: material
    conditions:
      variant: Xensation Core
      basis: typical measured values, unstrengthened glass
    method: Printed as 32 kN/mm2 in the Shear modulus row, Core column.
    status: ground
    source: schott-xensation
    where: Mechanical properties table, Shear modulus row, Core column
  - benchmark: poissons_ratio
    label: Poisson's ratio (SCHOTT Xensation Core)
    value: 0.22
    unit: '-'
    scope: material
    conditions:
      variant: Xensation Core
    method: Printed as 0.22 in the Poisson's ratio row, Core column.
    status: ground
    source: schott-xensation
    where: Mechanical properties table, Poisson's ratio row, Core column
  - benchmark: vickers_hardness
    label: Vickers hardness, unstrengthened (SCHOTT Xensation Core)
    value: 610
    unit: HV
    scope: material
    conditions:
      variant: Xensation Core
      state: unstrengthened
    method: Printed as 610 HV, unstrengthened, Core column.
    status: ground
    source: schott-xensation
    where: Mechanical properties table, Vickers hardness row, unstrengthened line
  - benchmark: vickers_hardness
    label: Vickers hardness, strengthened (SCHOTT Xensation Core)
    value: 670
    unit: HV
    scope: material
    conditions:
      variant: Xensation Core
      state: typical after chemical strengthening
    method: Printed as 670 HV in the strengthened line, Core column. SCHOTT says the values are typical after chemical strengthening.
    status: ground
    source: schott-xensation
    where: Mechanical properties table, Vickers hardness row, strengthened line
  - benchmark: flexural_strength
    label: Four-point bending strength, chemically strengthened (SCHOTT Xensation Core)
    value: 800
    unit: MPa
    scope: material
    conditions:
      variant: Xensation Core
      bound: printed as greater than 800 MPa
      state: after chemical strengthening
    method: Printed as capable of greater than 800 MPa for Core. Only the lower bound is printed.
    status: ground
    source: schott-xensation
    where: Mechanical properties table, 4-point bending strength row, Core column
  - benchmark: cte
    label: Mean linear expansion, 20 to 300 C (SCHOTT Xensation Core)
    value: 5
    unit: x10^-6/K
    scope: material
    conditions:
      variant: Xensation Core
      temperature_range: 20 to 300 C
    method: Printed as 5.0 x 10^-6 K^-1 for Core. The printed unit is kept.
    status: ground
    source: schott-xensation
    where: Thermal properties table, mean linear expansion row, Core column
  - benchmark: cte
    label: Mean linear expansion, 20 to 300 C (SCHOTT Xensation Up)
    value: 8.3
    unit: x10^-6/K
    scope: material
    conditions:
      variant: Xensation Up
      temperature_range: 20 to 300 C
    method: Printed as 8.3 x 10^-6 K^-1 for Up. The printed unit is kept.
    status: ground
    source: schott-xensation
    where: Thermal properties table, mean linear expansion row, Up column
  - benchmark: transformation_temperature
    label: Transformation temperature (SCHOTT Xensation Core)
    value: 580
    unit: C
    scope: material
    conditions:
      variant: Xensation Core
    method: Printed as 580 C in the transformation temperature row, Core column. Not a canonical name.
    status: ground
    source: schott-xensation
    where: Thermal properties table, transformation temperature row, Core column
  - benchmark: annealing_point
    label: Annealing point, 10^13 dPas (SCHOTT Xensation Core)
    value: 590
    unit: C
    scope: material
    conditions:
      variant: Xensation Core
      viscosity: 10^13 dPas
    method: Printed as 590 C at 10^13 dPas in the viscosity rows, Core column.
    status: ground
    source: schott-xensation
    where: Thermal properties table, viscosity rows, annealing point, Core column
  - benchmark: softening_point
    label: Softening point, 10^7.6 dPas (SCHOTT Xensation Core)
    value: 820
    unit: C
    scope: material
    conditions:
      variant: Xensation Core
      viscosity: 10^7.6 dPas
    method: Printed as 820 C at 10^7.6 dPas, Core column.
    status: ground
    source: schott-xensation
    where: Thermal properties table, viscosity rows, softening point, Core column
  - benchmark: working_point
    label: Working point, 10^4 dPas (SCHOTT Xensation Core)
    value: 1190
    unit: C
    scope: material
    conditions:
      variant: Xensation Core
      viscosity: 10^4 dPas
    method: Printed as 1190 C at 10^4 dPas, Core column.
    status: ground
    source: schott-xensation
    where: Thermal properties table, viscosity rows, working point, Core column
  - benchmark: refractive_index
    label: Refractive index, core glass (SCHOTT Xensation Core)
    value: 1.511
    unit: '-'
    scope: material
    conditions:
      variant: Xensation Core
      wavelength: 595 nm
    method: Printed as 1.511 for the core glass at 595 nm, Core column.
    status: ground
    source: schott-xensation
    where: Optical properties table, refractive index row, Core column
  - benchmark: dielectric_constant
    label: Dielectric constant (SCHOTT Xensation Core)
    value: 6.1
    unit: '-'
    scope: material
    conditions:
      variant: Xensation Core
      frequency: 54 MHz
      basis: extrapolated
    method: Printed as 6.1 at 54 MHz in the electrical table, Core column. SCHOTT labels these values as extrapolated.
    status: ground
    source: schott-xensation
    where: Electrical properties table, 54 MHz row, Core column
  - benchmark: dissipation_factor
    label: Loss tangent (SCHOTT Xensation Core)
    value: 0.009
    unit: '-'
    scope: material
    conditions:
      variant: Xensation Core
      frequency: 54 MHz
      basis: extrapolated
    method: Printed as 0.009 at 54 MHz in the electrical table, Core column.
    status: ground
    source: schott-xensation
    where: Electrical properties table, 54 MHz row, Core column
  - benchmark: annealing_point
    label: Annealing point, Corning code 1723 (aluminosilicate window glass)
    value: 710
    unit: C
    scope: material
    conditions:
      product: Corning Code 1723 aluminosilicate glass
      note: stated as the annealing point of this glass
    method: Printed in the text as 710 C for this glass, in the results on refractive index. Read from OCR text, so verify with the page image if in doubt.
    status: ground
    source: nasa-1968-apollo-windows
    where: Results and conclusions, section 1 (refractive index), report page 69
corrosion:
  - environment: Weathering by atmospheric water and carbon dioxide (EAGLE XG)
    headline: EAGLE XG is rated weathering class 1, which almost never shows weathering effects
    effect: Corning defines weathering as corrosion by atmospheric gases and vapour such as water and carbon dioxide. Class 1 glasses will almost never show weathering effects, class 2 occasionally, and class 3 need careful consideration. No test duration is printed.
    rating: low
    conditions:
      product: EAGLE XG
      basis: Corning weathering class
    source: eagle-xg-mie301
    where: Chemical block, Weathering row
  - environment: Hydrofluoric acid 10 percent, 20 min, 20 C (EAGLE XG)
    headline: Hydrofluoric acid removes the most glass of the EAGLE XG reagents tested
    effect: Weight loss 5.18 mg/cm2 in the EAGLE XG durability table, the largest of the reagents listed. NH4F:HF 10 percent for the same time gives 0.84 mg/cm2.
    rating: unknown
    conditions:
      time: 20 min
      temperature: 20 C
      basis: Corning durability test; values depend strongly on test conditions
    source: eagle-xg-mie301
    where: Chemical block, Durability table, HF 10% row
  - environment: Sodium hydroxide 5 percent, 6 h, 95 C (EAGLE XG)
    headline: EAGLE XG weight loss in hot sodium hydroxide is 1.83 mg/cm2 over 6 h
    effect: Weight loss 1.83 mg/cm2 in the EAGLE XG durability table. Na2CO3 0.02N for 6 h at 95 C gives 0.16 mg/cm2.
    rating: unknown
    conditions:
      time: 6 h
      temperature: 95 C
    source: eagle-xg-mie301
    where: Chemical block, Durability table, NaOH 5% row
  - environment: Deionised water, 24 h, 95 C (EAGLE XG)
    headline: No measurable weight loss in hot deionised water
    effect: Weight loss printed as 0.00 mg/cm2 for 24 h at 95 C in the EAGLE XG durability table.
    rating: unknown
    conditions:
      time: 24 h
      temperature: 95 C
    source: eagle-xg-mie301
    where: Chemical block, Durability table, DI H2O row
  - environment: Hydrofluoric acid 10 percent, 20 min, 20 C (Gorilla Glass 2)
    headline: Gorilla Glass 2 loses more to hydrofluoric acid than EAGLE XG does
    effect: Weight loss 11.88 mg/cm2 in the Gorilla Glass 2 chemical durability table, against 5.18 mg/cm2 for EAGLE XG in the same reagent and time.
    rating: unknown
    conditions:
      time: 20 min
      temperature: 20 C
      product: Gorilla Glass 2
    source: gorilla-glass-2
    where: Chemical Durability table, HF 10% row
  - environment: Sodium hydroxide 5 percent, 6 h, 95 C (Gorilla Glass 2)
    headline: Gorilla Glass 2 weight loss in hot sodium hydroxide
    effect: Weight loss 1.42 mg/cm2 in the Gorilla Glass 2 chemical durability table.
    rating: unknown
    conditions:
      time: 6 h
      temperature: 95 C
      product: Gorilla Glass 2
    source: gorilla-glass-2
    where: Chemical Durability table, NaOH-5% row
  - environment: Alkaline solution, DIN ISO 695 (SCHOTT Xensation Core)
    headline: Core is alkali class A2 and loses 104 mg/dm2 in 3 h
    effect: SCHOTT prints alkali class A2 and surface weight loss 104 mg/dm2 after 3 h for Core. Alpha is A2 at 92 mg/dm2 and Up is A1 at 42 mg/dm2. Values are for unstrengthened glass.
    rating: unknown
    conditions:
      variant: Xensation Core
      test: DIN ISO 695
      time: 3 h
      basis: class letter printed by SCHOTT; no rating scale in the datasheet
    source: schott-xensation
    where: Chemical properties table, alkali resistance rows
  - environment: Acid, DIN 12 116, 6 h (SCHOTT Xensation Core)
    headline: Core is acid class S3 with 8.5 mg/dm2 half surface weight loss
    effect: SCHOTT prints acid class S3 and half surface weight loss 8.5 mg/dm2 after 6 h for Core. Alpha is S2 at 1.4 mg/dm2 and Up is S4 at 19 mg/dm2.
    rating: unknown
    conditions:
      variant: Xensation Core
      test: DIN 12 116
      time: 6 h
    source: schott-xensation
    where: Chemical properties table, acid resistance rows
  - environment: Water, DIN ISO 719 (SCHOTT Xensation Core)
    headline: Core is hydrolytic class HGB 1, with 21 ug/g Na2O released from grains
    effect: SCHOTT prints hydrolytic class HGB 1 and an equivalent of 21 ug/g Na2O per gram of glass grains for Core. Alpha is HGB1 at 32 ug/g and Up is HGB2 at 38 ug/g.
    rating: unknown
    conditions:
      variant: Xensation Core
      test: DIN ISO 719
    source: schott-xensation
    where: Chemical properties table, hydrolytic resistance rows
risks:
  hazards:
    - text: 'PubChem aggregated GHS for potassium nitrate, the salt used for the ion-exchange bath: H272 (may intensify fire; oxidizer, Danger) and H319 (causes serious eye irritation, Warning). These classes describe the salt, not the finished glass.'
      ghs:
        - H272
        - H303
        - H315
        - H319
        - H335
      source: pubchem-potassium-nitrate
      where: GHS Classification, Potassium Nitrate (CID 24434)
  failure_risks:
    - mode: Loss of the compressive layer if ion exchange runs too hot
      trigger: Ion exchange at or above the annealing range
      consequence: Zeng et al. ran the treatment below the annealing range so that the stress introduced is not removed by relaxation.
      severity: moderate
      source: zeng-2016
      where: Results, paragraph on compressive stress and depth of layer
    - mode: Strength limited by surface flaws
      trigger: Surface flaws from handling, scratching or impact
      consequence: Zeng et al. state that the practical strength of glasses is about two orders of magnitude lower than the theoretical value because of surface flaws. Gorilla Glass 2 has a fracture toughness of 0.68 MPa m0.5 (Corning sheet).
      severity: moderate
      source: zeng-2016
      where: Introduction, first two paragraphs
    - mode: Surface attack by hydrofluoric acid
      trigger: Contact with 10 percent hydrofluoric acid
      consequence: EAGLE XG loses 5.18 mg/cm2 in 20 min at 20 C (MIE 301). Gorilla Glass 2 loses 11.88 mg/cm2 under the same test (Corning sheet).
      severity: high
      source: eagle-xg-mie301
      where: Durability table, HF 10% row
    - mode: Surface attack in alkaline solution (Xensation Core)
      trigger: Contact with an alkaline solution in the DIN ISO 695 test
      consequence: Surface weight loss of 104 mg/dm2 after 3 h, alkali class A2 (SCHOTT typical value for unstrengthened Core glass).
      severity: moderate
      source: schott-xensation
      where: Chemical properties table, alkali resistance rows
  side_effects: []
  handling:
    - text: Handle the potassium nitrate bath as an oxidizer and an eye irritant (PubChem GHS H272 and H319).
      source: pubchem-potassium-nitrate
      where: GHS Classification
    - text: 'Hydrofluoric acid attacks the surface: 10 percent HF removes 5.18 mg/cm2 from EAGLE XG in 20 min at 20 C (Corning MIE 301).'
      source: eagle-xg-mie301
      where: Durability table
    - text: Keep the ion-exchange step below the annealing range and in the 390 to 430 C range used for the model glass (Zeng et al. used KNO3 at 390, 400, 410, 420 and 430 C for 2 to 10 h).
      source: zeng-2016
      where: Experimental section, ion exchange; Results
  mitigations: []
uses:
  - application: electronics-and-chips
    device: Touchscreen cover glass for phones and tablets
    example: Corning says Gorilla Glass 2 is an ideal protective cover for displays in smartphones, laptop and tablet screens, and touchscreen devices.
    source: gorilla-glass-2
    where: Applications list
  - application: electronics-and-chips
    device: Substrate for active-matrix flat-panel displays
    example: Corning's MIE 301 gives EAGLE XG's principal use as substrates for active-matrix flat-panel displays, in fusion-drawn sheet form.
    source: eagle-xg-mie301
    where: Glass type, forms and principal uses, page 1
  - application: solar-arrays
    device: Integral cover glass bonded to silicon solar cells
    example: NASA's 1971 final report on integral covers used Corning glass 1720, an aluminosilicate, as the cover in most evaporation tests, and called 1720 covers excellent candidates for lightweight array use after its electron-exposure test.
    source: nasa-1971-solar-covers
    where: Section 2.2, integral cover investigations; electron exposure results
  - application: habitats-and-suits
    device: Apollo spacecraft window
    example: A General Dynamics report for the Manned Spacecraft Center tested Corning Code 1723 aluminosilicate glass for Apollo windows. It found no refractive-index change to the third decimal after 30 days of space-equivalent irradiation, though the aluminosilicate sample showed charged-particle discharge tracks.
    source: nasa-1968-apollo-windows
    where: Results and conclusions, sections 1 and 2
supply:
  - subject: Potash (potassium, as K2O) for potassium salts used in the ion-exchange bath
    abundance: 'USGS: world potash mine production about 49,000 thousand t K2O equivalent in 2025 (estimated), and world reserves of more than 5.9 billion t K2O equivalent.'
    producers:
      - country: Canada
        production: 15,000 thousand t K2O equivalent (2025e)
        year: 2025
      - country: Russia
        production: 10,000 thousand t K2O equivalent (2025e)
        year: 2025
      - country: Belarus
        production: 6,000 thousand t K2O equivalent (2025e)
        year: 2025
      - country: China
        production: 6,300 thousand t K2O equivalent (2025e)
        year: 2025
    critical_lists: []
    recycling: 'USGS: no recycling is reported for potash.'
    substitutes: []
    source: usgs-potash-2026
    where: Mine production and reserves table; Recycling
  - subject: Potash, United States import sources
    abundance: 'USGS: potash import sources 2021 to 2024, as printed. Net import reliance was 92 percent of apparent US consumption in 2025 (estimated).'
    producers:
      - country: Canada
        share_percent: 79
        year: 2024
        basis: import sources 2021-24, as printed
      - country: Russia
        share_percent: 12
        year: 2024
        basis: import sources 2021-24, as printed
      - country: Israel
        share_percent: 3
        year: 2024
        basis: import sources 2021-24, as printed
      - country: Other
        share_percent: 6
        year: 2024
        basis: import sources 2021-24, as printed
    critical_lists: []
    recycling: 'USGS: none.'
    substitutes: []
    source: usgs-potash-2026
    where: Import Sources (2021-24); Salient statistics, net import reliance (2025e value 92 percent)
documents:
  - title: EAGLE XG AMLCD glass substrates, material information MIE 301 (Corning, January 2006; copy hosted by Valley Design)
    type: datasheet
    url: https://valleydesign.com/wp-content/uploads/2023/11/corning-eagle-xg-glass.pdf
    year: 2006
  - title: Corning Gorilla Glass 2 product information (copy hosted by Valley Design, Rev B, January 2012)
    type: datasheet
    url: https://valleydesign.com/wp-content/uploads/2023/11/corning-gorilla-glass.pdf
    year: 2012
  - title: Xensation technical details (SCHOTT)
    type: datasheet
    url: https://www.schott.com/en-gb/products/xensation/technical-details
  - title: Mechanical-structural investigation of chemical strengthening aluminosilicate glass through introducing phosphorus pentoxide (Zeng et al., Frontiers in Materials, open access)
    type: paper
    url: https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2016.00053/pdf
    year: 2016
  - title: Evaluation of the effects of space environment exposure on index of refraction and extinction coefficients of Apollo window materials (General Dynamics, NASA contract report, April 1968)
    type: report
    url: https://ntrs.nasa.gov/api/citations/19680010998/downloads/19680010998.pdf
    year: 1968
  - title: Development of integral covers on solar cells, final report June 1970 to June 1971 (NASA Goddard Space Flight Center contract)
    type: report
    url: https://ntrs.nasa.gov/api/citations/19720006385/downloads/19720006385.pdf
    year: 1971
  - title: 'Mineral Commodity Summaries 2026: Potash (USGS)'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-potash.pdf
    year: 2026
  - title: Potassium nitrate, PubChem CID 24434, GHS classification
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/24434/JSON
  - title: Gorilla Glass (Wikipedia)
    type: report
    url: https://en.wikipedia.org/wiki/Gorilla_Glass
gaps:
  - 'Non-canonical property names used because spores/property-canon.yaml has no entry for them: softening_point, annealing_point, strain_point, working_point, vickers_hardness, fracture_toughness, transformation_temperature, compressive_stress_capability, depth_of_layer, log10_volume_resistivity. The canon file needs them added before import.'
  - 'Corning current product sheets for EAGLE XG (2021 and 2023 editions) and Gorilla Glass 3, Victus and Victus 2 could not be fetched: corning.com returned Access Denied (HTTP 403) to automated download, and the valleydesign copies are the 2006 EAGLE XG and 2012 Gorilla Glass 2 sheets. Search snippets quoted newer figures (for example EAGLE XG 74 GPa and 32 x10^-7/C in a 2023 sheet), but these were not read as pages in this run and are not used.'
  - EAGLE XG composition is not printed in MIE 301 (it is described only as an alkaline-earth boro-aluminosilicate), so no recipe shares are given for EAGLE XG.
  - Vickers hardness of EAGLE XG (640 at 200 g, 25 s) is printed without a unit in MIE 301, so it is left out.
  - 'Potassium aluminosilicate: no fetched source gives a potassium-rich aluminosilicate composition or its properties. Potassium enters as the exchange ion in the KNO3 bath (Zeng et al.; Wikipedia).'
  - 'Alumina and bauxite supply: the USGS bauxite summary was not reachable as a PDF in this run, so alumina is not covered in the supply section. The USGS aluminum summary was read but gives aluminium metal smelter output, not alumina, so it is not used.'
  - Critical-mineral status of potassium and aluminium oxide was not checked in this run.
  - 'Humidity and water-fatigue ageing of alkali or alkaline-earth aluminosilicate glass: no open paper with numeric results was opened. The Liu et al. 2020 paper (Physical Review Materials) concerns caesium aluminoborate glass and is not used. The Striepe et al. 2013 alkaline-earth aluminosilicate paper was not reachable as a PDF.'
  - 'Space radiation: NASA 1971 reports transmission losses after 1 MeV electron exposure for glass 1720, but the percentages in the OCR text are not clean enough to use as values, so they appear only in narrative text. No UV or radiation table with numbers was read for Gorilla Glass or EAGLE XG.'
  - Chemical strengthening outputs (compressive stress and depth of layer) for the model glass are shown only as a figure in Zeng et al. (Figure 5), so no numeric CS or DOL is taken from that paper. The 30 to 75 um depth of layer quoted by Zeng et al. from earlier work is not used as a property.
  - Potassium nitrate GHS classes come from PubChem's aggregated notifications for the salt, not from an SDS for the glass or the bath. No SDS for the ion-exchange bath was read in this run.
  - SCHOTT's Xensation page describes sodium-ion exchange, while Corning, Zeng et al. and Wikipedia describe potassium exchange. The sources are reported as printed and the difference is not resolved.
  - The SCHOTT Xensation values are for the Core, Alpha and Up variants of the Xensation family. The page does not name which variant is sold as Xensation Cover, so the variant is stated for each value.
  - Dielectric constant and loss tangent are measured at different frequencies in each source (1 kHz for EAGLE XG, 50 MHz for Gorilla Glass 2, 54 MHz for Xensation). The values are not directly comparable.
  - Corning's durability weight losses are for the stated reagent and time only. Corning says values are highly dependent on test conditions, so the table is not a service-life measure.
sources:
  eagle-xg-mie301:
    title: Corning EAGLE XG AMLCD glass substrates, material information MIE 301
    id: Corning Display Technologies, MIE 301, issued January 2006 (copy hosted by Valley Design)
    url: https://valleydesign.com/wp-content/uploads/2023/11/corning-eagle-xg-glass.pdf
    kind: datasheet
    year: 2006
    license: manufacturer document, cited not reproduced
  gorilla-glass-2:
    title: Corning Gorilla Glass 2 product information sheet
    id: Corning Incorporated, Gorilla Glass 2 product information, Rev B, January 2012 (copy hosted by Valley Design)
    url: https://valleydesign.com/wp-content/uploads/2023/11/corning-gorilla-glass.pdf
    kind: datasheet
    year: 2012
    license: manufacturer document, cited not reproduced
  schott-xensation:
    title: Xensation technical details
    id: SCHOTT AG, Xensation technical details page
    url: https://www.schott.com/en-gb/products/xensation/technical-details
    kind: web
    license: manufacturer web page, cited not reproduced
  zeng-2016:
    title: Mechanical-structural investigation of chemical strengthening aluminosilicate glass through introducing phosphorus pentoxide
    id: Zeng H, Wang L, Ye F, Yang B, Chen J, Chen G, Sun L. Frontiers in Materials 3:53 (2016), doi 10.3389/fmats.2016.00053
    url: https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2016.00053/pdf
    kind: paper
    year: 2016
    license: open access, CC BY
  nasa-1968-apollo-windows:
    title: Evaluation of the effects of space environment exposure on index of refraction and extinction coefficients of Apollo window materials
    id: NASA contract report, General Dynamics Corporation, April 1968, NTRS 19680010998
    url: https://ntrs.nasa.gov/api/citations/19680010998/downloads/19680010998.pdf
    kind: report
    year: 1968
    license: US government work, public domain
  nasa-1971-solar-covers:
    title: Development of integral covers on solar cells
    id: NASA Goddard Space Flight Center contract report, final report June 1970 to June 1971, NTRS 19720006385
    url: https://ntrs.nasa.gov/api/citations/19720006385/downloads/19720006385.pdf
    kind: report
    year: 1971
    license: US government work, public domain
  usgs-potash-2026:
    title: 'Mineral Commodity Summaries 2026: Potash'
    id: USGS, MCS 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-potash.pdf
    kind: report
    year: 2026
    license: US government work, public domain
  pubchem-potassium-nitrate:
    title: Potassium nitrate, PubChem CID 24434
    id: PubChem, GHS classification of potassium nitrate
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/24434/JSON
    kind: database
    license: PubChem, public domain
  wikipedia-gorilla-glass:
    title: Gorilla Glass
    id: Wikipedia, Gorilla Glass
    url: https://en.wikipedia.org/wiki/Gorilla_Glass
    kind: web
    license: CC BY-SA 4.0
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 52
  unreachable: 4
  caveats: 6
  note: 'Written by an AI assistant on 2026-10-26 from sources read in this run: Corning MIE 301 (EAGLE XG, 2006) and Gorilla Glass 2 sheet (2012) as copies hosted by Valley Design, SCHOTT Xensation technical details, Zeng et al. 2016 (Frontiers, open access), NASA 1968 Apollo window report and NASA 1971 integral cover report, USGS potash 2026, PubChem potassium nitrate. Corning current sheets and the USGS bauxite summary could not be read. Numbers from search snippets are not used.'
story:
  recipe:
    line: Aluminosilicate glass is a silica network modified by alumina and alkali or alkaline-earth oxides. Alkali aluminosilicate glass (Gorilla type) is strengthened by immersing it in a hot potassium-salt bath, which swaps smaller sodium ions in the surface for larger potassium ions (Wikipedia; Zeng et al. 2016). The model glass in Zeng et al. is melted at high temperature, cast in a preheated brass mold and annealed to relieve internal stress. Corning does not publish the EAGLE XG or Gorilla batch recipe.
    parts:
      - name: Silica
        symbol: SiO2
        share: about 67 mol% of the base glass
        role: Network former. It forms the glass framework.
        share_percent: 67
      - name: Sodium oxide
        symbol: Na2O
        share: about 25 mol% of the base glass
        role: Network modifier. Its sodium ions are the ones that potassium replaces in the ion-exchange bath.
        share_percent: 25
      - name: Alumina
        symbol: Al2O3
        share: about 8 mol% of the base glass
        role: Intermediate oxide that gives the aluminosilicate network its name.
        share_percent: 8
      - name: Phosphorus pentoxide
        symbol: P2O5
        share: 1 to 7 mol% added to the base glass
        role: Added in Zeng et al. to raise compressive stress, depth of layer and hardness. It makes the silicate network less polymerised, which speeds ion exchange.
    source: zeng-2016
    where: Experimental section, glass preparation and compositions; Results on micro-Raman spectra. The Corning and SCHOTT compositions are not printed.
  risk_groups:
    - title: For people
      level: 0
      verdict: Potassium nitrate bath is an oxidizer and eye irritant
      lead: The finished glass has no hazard class in the sources read. The hazard data read are for the potassium nitrate used in the ion-exchange bath (PubChem GHS H272 and H319) and for the glass edges.
      points:
        - label: Sharp edges
          line: Broken aluminosilicate glass is sharp. Handle broken pieces with gloves and dispose of them in a sharps container.
        - label: Potassium nitrate bath
          line: PubChem's aggregated GHS for potassium nitrate is H272, may intensify fire (oxidizer, Danger), and H319, causes serious eye irritation (Warning). These describe the salt, not the glass.
        - label: Hydrofluoric acid
          line: 'Hydrofluoric acid etches the surface: EAGLE XG loses 5.18 mg/cm2 in 20 min at 20 C (Corning MIE 301).'
  why: 'Aluminosilicate glass is the choice when a thin glass must be hard and chemically strengthened. The datasheets read here give high strain and softening points (EAGLE XG strain point 669 C, softening point 971 C), and chemical strengthening adds a surface layer under compression. The trade-off is cost and processing: a high working temperature (EAGLE XG 1293 C) and a salt-bath step.'
  uses:
    - where: Phone and tablet covers
      line: Corning gives Gorilla Glass 2 as an ideal protective cover for smartphone, laptop and tablet screens, and touchscreen devices.
    - where: Flat-panel display substrates
      line: EAGLE XG is made as fusion-drawn sheet for active-matrix flat-panel display substrates (Corning MIE 301).
    - where: Solar-array covers
      line: NASA's 1971 integral cover work used Corning glass 1720, an aluminosilicate, as the cover in most evaporation tests, and called 1720 covers excellent candidates for lightweight arrays.
    - where: Apollo windows
      line: A 1968 General Dynamics report for the Manned Spacecraft Center tested Corning Code 1723 aluminosilicate for Apollo windows. After 30 days of space-equivalent irradiation, no refractive-index change showed to the third decimal.
  can_do:
    - label: Density
      benchmark: density
      value: 2.38 g/cc (EAGLE XG)
      line: Corning gives 2.38 g/cc at 20 C for EAGLE XG. Gorilla Glass 2 is 2.42 g/cm3 and SCHOTT Xensation Core is 2.38 g/cm3.
    - label: Working point
      benchmark: working_point
      value: 1293 C (EAGLE XG)
      line: Corning gives a working point of 1293 C at 10^4 poises for EAGLE XG.
    - label: Hardness after ion exchange
      benchmark: vickers_hardness
      value: 5.5 to 6.1 GPa (model glass)
      line: Zeng et al. report that ion exchange at 400 C for 6 h raises the Vickers hardness of the model glass from 5.5 to 6.1 GPa as P2O5 rises from 1 to 7 mol%.
    - label: Compressive stress capability
      benchmark: compressive_stress_capability
      value: 1000 MPa at 40 um depth of layer
      line: Corning prints 1000 MPa at 40 um depth of layer, and 950 MPa at 50 um, for Gorilla Glass 2.
  compare: Among the sources read here, EAGLE XG has a density of 2.38 g/cc, a strain point of 669 C and a working point of 1293 C. Gorilla Glass 2 is denser at 2.42 g/cm3 and has a lower strain point of 599 C, but it is the one with a stated chemical strengthening capability of 1000 MPa at 40 um depth of layer. SCHOTT's Xensation Core is 2.38 g/cm3 with a transformation temperature of 580 C, and its Up variant has a larger expansion of 8.3 x10^-6/K against 5.0 for Core.
  compare_rows:
    - scope: material
      label: Density
      benchmark: density
    - scope: material
      label: Linear thermal expansion
      benchmark: cte
    - scope: material
      label: Softening point
      benchmark: softening_point
  handling:
    - Keep hydrofluoric acid away from the glass surfaces. EAGLE XG loses 5.18 mg/cm2 in 20 min at 20 C in 10 percent HF (Corning MIE 301).
    - 'Use eye protection with the potassium nitrate bath: PubChem classes it as an oxidizer (H272) and eye irritant (H319).'
    - Run ion exchange below the annealing range, as Zeng et al. did, so that the stress is not lost to relaxation.
  good_for:
    - Thin cover glass for displays and touchscreens, where a chemically strengthened surface and hardness matter.
    - Flat-panel display substrates, where EAGLE XG's low alkali content and high strain point matter (Corning MIE 301 gives total alkali of about 0.1 wt percent).
    - Lightweight solar-array covers, as NASA's 1971 work suggested for glass 1720.
  watch_out:
    - 'Processing is hotter and costlier than soda-lime glass: EAGLE XG has a working point of 1293 C and the strengthened glass needs a salt bath.'
    - Corning's durability table shows the glass is strongly attacked by hydrofluoric acid. Keep HF away from the surface.
    - No humidity-ageing or radiation-ageing data for chemically strengthened aluminosilicate glass were read in this run. The 1968 Apollo test ran for 30 days of equivalent dose only.
  verdict: Aluminosilicate glass is the strong, thin choice for display and cover glass when the glass is chemically strengthened. The datasheets agree on density, strain point and hardness. The sources read here do not give ageing or flight-life data for chemically strengthened aluminosilicate, so flight use needs its own test.