Alkali-free glass
AssigneeAGC Inc.
InventorsHirofumi Tokunaga, Kazutaka Ono
Life of this patent
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Abstract
An alkali free glass has an average coefficient of thermal expansion at 50 to 350° C. of 30×10−7 to 43×10−7/° C., a Young's modulus of 88 GPa or more, a strain point of 650 to 725° C., a temperature T4 at which a viscosity reaches 104 dPa·s of 1,290° C. or lower, a glass surface devitrification temperature (Tc) of T4+20° C. or lower, and a temperature T2 at which the viscosity reaches 102 dPa·s of 1,680° C. or lower. The alkali free glass contains, as represented by mol % based on oxides, 62 to 67% of SiO2, 12.5 to 16.5% of Al2O3, 0 to 3% of B2O3, 8 to 13% of MgO, 6 to 12% of CaO, 0.5 to 4% of SrO, and 0 to 0.5% of BaO. MgO+CaO+SrO+BaO is 18 to 22%, and MgO/CaO is 0.8 to 1.33.
Claims18
An alkali free glass
- comprising SiO2 as a main component, Al2O3, and B2O3,
- wherein the alkali free glass comprises, as represented by mol % based on oxides:
- 62 to 67% of SiO2,
- 9 to 13% of MgO,
- 6 to 12% of CaO,
- 0.5 to 2.5% of SrO, and
- 0 to 0.5% of BaO,
- wherein MgO/CaO is 1.1 or more,
- wherein the alkali free glass has a value expressed by the following Expression (I) of 4.6 or less:
- (7.87[Al2O3]−8.5[B2O3]+11.35[MgO]+7.09[CaO]+5.52[SrO]−1.45[BaO])/[SiO2] Expression (I)
- wherein the alkali free glass has a value expressed by the following Expression (II) of 1.06 to 1.32:
- (−1.02[Al2O3]+10.79[B2O3]+2.84[MgO]+4.12[CaO]+5.19[SrO]+3.16[BaO])/[SiO2] Expression (II)
- wherein the alkali free glass has a value expressed by the following Expression (III) of 4.09 to 4.8:
- (8.9[Al2O3]+4.26[B2O3]+11.3[MgO]+4.54[CaO]+0.1[SrO]−9.98[BaO])×{1+([MgO]/[CaO]−1)2}/[SiO2] Expression (III).
Dependencies are inferred from the claim text.