Non-iox glasses with high coefficient of thermal expansion and preferential fracture behavior for thermal tempering
AssigneeCorning Incorporated
InventorsTimothy Michael Gross, Peter Joseph Lezzi
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Abstract
The disclosure relates to glass compositions with high coefficients of thermal expansion and low fracture toughness designed for thermal tempering. These glasses are ideally suited to produce a “dicing” pattern when thermally tempered, even when thin (<3 mm). Disclosed glasses have high thermal expansions at low and high temperatures to produce increased temper stresses once quenched, coupled with low fracture toughness which promotes crack bifurcation and enhanced frangibility. Methods of making such glasses are also provided.
Claims20
A method of making a glass article, comprising:
- mixing and melting batch constituents comprising:
- from 75 to 90 mol % SiO2;
- from 7 to 20 mol % Al2O3;
- greater than 0 to 20 mol % of at least one alkaline earth oxide selected from the group consisting of MgO, CaO, BaO, or SrO;
- from 8 to 20 mol % K2O;
- greater than 0 to 10 mol % B2O3, and
- 0 mol % Na2O to form a melt of the glass,
- wherein a low temperature coefficient of thermal expansion from 25° C. to 300° C. of the glass is greater than 75×10−7 ppm/° C., and
- wherein a fracture toughness, KIC of the glass is less than 0.65 MP·m1/2.
A method of making a glass article, comprising:
- mixing and melting batch constituents comprising:
- from 75 to 90 mol % SiO2;
- from 7 to 20 mol % Al2O3;
- greater than 0 to 20 mol % of at least one alkaline earth oxide selected from the group consisting of MgO, CaO, BaO, or SrO;
- from 8 to 20 mol % K2O;
- and
- greater than 0 to 2.57 mol % B2O3 to form a melt of the glass,
- wherein the glass exhibits a 200 Poise temperature that is within a range of from 1684° C. to 1762° C.
Dependencies are inferred from the claim text.