Ion exchangeable soft glasses for three-dimensional shapes
Ion exchangeable alkali aluminosilicate glasses and glass articles having softening points and high temperature coefficients of thermal expansion that permit the glass to be formed into three-dimensional shapes by the vacuum sagging process are provided. These glasses contain significant amounts of at least one of MgO and ZnO and comprise B 2 O 3 and less than 1 mol % Li 2 O.
1. An alkali aluminosilicate glass, the alkali aluminosilicate glass comprising from 62 mol % to about 70 mol % SiO 2 , from 0.75 mol % to 4 mol % B 2 O 3 , greater than 5 mol % Al 2 O 3 , MgO, and from about 1 mol % to about 7 mol % ZnO, wherein the alkali aluminosilicate glass is substantially free of Li 2 O, wherein the alkali aluminosilicate glass has a softening point of 790° C. or less and a high temperature coefficient of thermal expansion of about 35×10 −6 /K or less, and wherein the alkali aluminosilicate glass is formable into a three-dimensional non-planar shape, and is chemically strengthened and has a compressive layer extending to a depth of layer of at least about 40 μm from at least one surface of the alkali aluminosilicate glass into the alkali aluminosilicate glass.
2. The alkali aluminosilicate glass of claim 1 , wherein the compressive layer has a maximum compressive stress of at least about 600 MPa.
3. The alkali aluminosilicate glass of claim 2 , wherein the depth of layer is at least about 50 μm.
4. The alkali aluminosilicate glass of claim 2 , wherein the maximum compressive stress is at least about 750 MPa.
5. The alkali aluminosilicate glass of claim 2 , wherein the alkali aluminosilicate glass is ion exchanged for ten hours or less in a single ion exchange bath.
6. The alkali aluminosilicate glass of claim 2 , wherein the alkali aluminosilicate glass comprises at least a portion of a cover glass or a housing of a consumer electronic product.
7. The alkali aluminosilicate glass of claim 6 , wherein at least one of the cover glass and the housing has a thickness from about 0.25 mm to about 2.0 mm.
8. The alkali aluminosilicate glass of claim 1 , wherein the alkali aluminosilicate glass comprises: from 62 mol % to about 70 mol % SiO 2 ; from greater than 5 mol % to about 11 mol % Al 2 O 3 ; from 0.75 mol % to 4 mol % B 2 O 3 ; less than 1 mol % Li 2 O; from about 13 mol % to about 19 mol % Na 2 O; from about 0.3 mol % to about 4 mol % K 2 O; from greater than 0 mol % to about 6 mol % MgO; and from about 1 mol % to about 7 mol % ZnO.
9. The alkali aluminosilicate glass of claim 8 , wherein the alkali aluminosilicate glass comprises: from about 64 mol % to about 67 mol % SiO 2 ; from greater than 5 mol % to about 10 mol % Al 2 O 3 ; 0 mol % Li 2 O; from about 13 mol % to about 17 mol % Na 2 O; and from about 1 mol % to about 4 mol % K 2 O.
10. The alkali aluminosilicate glass of claim 9 , wherein the alkali aluminosilicate glass comprises from about 4 mol % to about 7 mol % ZnO.
11. The alkali aluminosilicate glass of claim 8 , wherein the alkali aluminosilicate glass comprises from 0.75 mol % to 2.5 mol % B 2 O 3 and from about 15 mol % to about 19 mol % Na 2 O.
12. The alkali aluminosilicate glass of claim 8 , comprising at least one of from 0 mol % to about 3 mol % P 2 O 5 and from 0 mol % to about 4 mol % ZrO 2 .
13. The alkali aluminosilicate glass of claim 8 , wherein the alkali aluminosilicate glass comprises up to about 0.5 mol % of at least one of SnO 2 and Sb 2 O 3 .
14. The alkali aluminosilicate glass of claim 1 , wherein R 2 O (mol %)/Al 2 O 3 (mol %)≥1.5, where R 2 O=(Li 2 O+Na 2 O+K 2 O+Rb 2 O+Cs 2 O).
15. The alkali aluminosilicate glass of claim 1 , wherein the alkali aluminosilicate glass has a 200 poise temperature T 200 of 1620° C. or less.
16. The alkali aluminosilicate glass of claim 1 , wherein the alkali aluminosilicate glass has a liquidus viscosity of at least 150 kP.
17. The alkali aluminosilicate glass of claim 1 , wherein the alkali aluminosilicate glass has a zircon breakdown viscosity of less than 30 kP.
18. An alkali aluminosilicate glass, the alkali aluminosilicate glass comprising: from 62 mol % to about 70 mol % SiO 2 ; from greater than 5 mol % to about 11 mol % Al 2 O 3 ; from 0.75 mol % to 4 mol % B 2 O 3 ; from about 13 mol % to about 19 mol % Na 2 O; from about 0.3 mol % to about 4 mol % K 2 O; from greater than 0 mol % to about 6 mol % MgO; and from about 1 mol % to about 7 mol % ZnO, wherein the alkali aluminosilicate glass is substantially free of Li 2 O, the alkali aluminosilicate glass having a softening point of 790° C. or less and a high temperature coefficient of thermal expansion of about 35×10 −6 /K or less, and the alkali aluminosilicate glass is chemically strengthened and has a compressive layer extending to a depth of layer of at least about 40 μm from at least one surface of the alkali aluminosilicate glass into the alkali aluminosilicate glass.
19. The alkali aluminosilicate glass of claim 18 , wherein the alkali aluminosilicate glass comprises: from about 64 mol % to about 67 mol % SiO 2 ; from greater than 5 mol % to about 10 mol % Al 2 O 3 ; 0 mol % Li 2 O; from about 13 mol % to about 17 mol % Na 2 O; and from about 1 mol % to about 4 mol % K 2 O.
20. The alkali aluminosilicate glass of claim 18 , wherein the alkali aluminosilicate glass comprises from about 4 mol % to about 7 mol % ZnO.
21. The alkali aluminosilicate glass of claim 18 , wherein the alkali aluminosilicate glass comprises from 0.75 mol % to 2.5 mol % B 2 O 3 and from about 15 mol % to about 19 mol % Na 2 O.
22. The alkali aluminosilicate glass of claim 18 , comprising at least one of from 0 mol % to about 3 mol % P 2 O 5 and from 0 mol % to about 4 mol % ZrO 2 .
23. The alkali aluminosilicate glass of claim 18 , wherein the alkali aluminosilicate glass comprises up to about 0.5 mol % of at least one of SnO 2 and Sb 2 O 3 .
24. The alkali aluminosilicate glass of claim 18 , wherein R 2 O (mol %)/Al 2 O 3 (mol %)≥1.5, where R 2 O=(Li 2 O+Na 2 O+K 2 O+Rb 2 O+Cs 2 O).
25. The alkali aluminosilicate glass of claim 18 , wherein the compressive layer has a maximum compressive stress of at least about 600 MPa.
26. The alkali aluminosilicate glass of claim 25 , wherein the depth of layer is at least about 50 μm.
27. The alkali aluminosilicate glass of claim 25 , wherein the maximum compressive stress is at least about 750 MPa.
28. The alkali aluminosilicate glass of claim 25 , wherein the alkali aluminosilicate glass is ion exchanged for ten hours or less in a single ion exchange bath.
29. The alkali aluminosilicate glass of claim 25 , wherein the alkali aluminosilicate glass comprises at least a portion of a cover glass or a housing of consumer electronic product.
30. The alkali aluminosilicate glass of claim 25 , wherein at least one of the cover glass and the housing has a thickness from about 0.25 mm to about 1.0 mm.
31. The alkali aluminosilicate glass of claim 18 , wherein the alkali aluminosilicate glass has a 200 poise temperature T 200 of 1620° C. or less.
32. The alkali aluminosilicate glass of claim 18 , wherein the alkali aluminosilicate glass has a liquidus viscosity of at least 150 kP.
33. The alkali aluminosilicate glass of claim 18 , wherein the alkali aluminosilicate glass has a zircon breakdown viscosity of less than 30 kP.
34. The alkali aluminosilicate glass of claim 18 , wherein the alkali aluminosilicate glass is formable into a three-dimensional non-planar shape.