Alkali-free glass
AssigneeAGC Inc.
InventorsYuya Hamada, Hirofumi Tokunaga
Life of this patent
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Abstract
The present invention relates to an alkali-free glass having a strain point of 700° C. or higher and 740° C. or lower, a density of 2.6 g/cm3 or lower, a Young's modulus of 90 GPa or higher and 100 GPa or lower, an average coefficient of thermal expansion at 50° C. to 350° C. of 30×10−7/K or higher and 39×10−7/K or lower, a temperature T2 at which a glass viscosity reaches 102 dPa·s of 1590° C. or higher and 1690° C. or lower, a temperature T4 at which the glass viscosity reaches 104 dPa·s of 1350° C. or lower, a glass surface devitrification temperature (Tc) of lower than (T4+80)° C., and a specific elastic modulus of 36 MN·m/kg or higher, and including a prescribed glass composition.
Claims14
An alkali-free glass having a strain point of 700° C. or higher and 740° C. or lower, a density of 2.6 g/cm3 or lower, a Young's modulus of 90 GPa or higher and 100 GPa or lower, an average coefficient of thermal expansion at 50° C. to 350° C. of 30×10−7/K or higher and 39×10−7/K or lower, a temperature T2 at which a glass viscosity reaches 102 dPa·s of 1590° C. or higher and 1690° C. or lower, a temperature T4 at which the glass viscosity reaches 104 dPa·s of 1350° C. or lower, a glass surface devitrification temperature (Tc) of lower than (T4+80)° C., and a specific elastic modulus of 36 MN·m/kg or higher, the alkali-free glass comprising:
- as represented by mol % based on oxides,
- SiO2:
- 55% or higher and 80% or lower;
- Al2O3:
- 12% or higher and 20% or lower;
- B2O3:
- 0.3% or higher and 5% or lower;
- MgO:
- 5% or higher and 18% or lower;
- CaO:
- 0.1% or higher and 12% or lower;
- SrO:
- 0.1% or higher and 8% or lower;
- and
- BaO:
- 0% or higher and 6% or lower;
- wherein
- MgO+CaO+SrO+BaO is 20% or lower,
- MgO/CaO is 1 or higher,
- MgO/(MgO+CaO+SrO+BaO) is 0.5 or higher,
- MgO+Al2O3 is 24% or higher and 38% or lower, and
- when Formula (I) is (−3.125×[SiO2]−2.394×[Al2O3]−3.511×[B2O3]−2.167×[MgO]−2.608×[CaO]−3.161×[SrO]−3.583×[BaO]+3.795×102), a value of Formula (T) is 90 or higher and 100 or lower.
Dependencies are inferred from the claim text.