Alkali-free glass
AssigneeAGC Inc.
InventorsHirofumi Tokunaga, Kazutaka Ono, Motoyuki Hirose
Life of this patent
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Abstract
An alkali-free glass having a strain point of 650° C. or more, an average coefficient of thermal expansion at 50 to 350° C. of from 30×10−7 to 45×10−7/° C., and a temperature T2 at which a glass viscosity reaches 102 dPa·s of from 1,500 to 1,800° C. The alkali-free glass contains, as represented by mol % based on oxides, SiO2: from 62 to 70%, Al2O3: from 9 to 16% B2O3: from 0 to 12%, MgO: from 3 to 10%, CaO: from 4 to 12%, SrO: from 0 to 6%, and Fe2O3: from 0.001 to 0.04%, provided that MgO+CaO+SrO+BaO is from 12 to 25%. The alkali-free glass has a β-OH value of from 0.35 to 0.85/mm.
Claims9
An alkali-free glass having a strain point of 650° C. or more, an average coefficient of thermal expansion at 50 to 350° C. of from 30×10−7 to 45×10−7/° C., and a temperature T2 at which a glass viscosity reaches 102 dPa·s of from 1,500 to 1,800° C., comprising, as represented by mol % based on oxides,
- SiO2:
- from 62 to 70%,
- Al2O3:
- from 9 to 16%
- B2O3:
- from 0.5 to 12%,
- MgO:
- from 5.6 to 10%,
- CaO:
- from 4 to 10%,
- SrO:
- from 0.1 to 6%, and
- Fe2O3:
- from 0.001 to 0.04%,
- provided that MgO+CaO+SrO+BaO is from 15.6 to 20.5%,
- wherein a value represented by the following formula A is from 10 to 20:
- (
- 3.119
- ×
- 10
- -
- 4
-
- T
- 2
- 2
- -
- 0.2014
- T
- 2
- -
- 17.38
- )
- [
- Fe
- 2
-
- O
- 3
- ]
- +
- (
- 6.434
- ×
- 10
- -
- 7
-
- T
- 2
- 2
- +
- 0.0144
- T
- 2
- -
- 7.842
- )
- [
- β
- -
- OH
- ]
- ,
- Formula
-
- A
- wherein [Fe2O3] is a numerical value represented by mol % of a total iron in terms of Fe2O3, and
- [β-OH] is a numerical value represented by a unit/mm.
Dependencies are inferred from the claim text.