Glasses having low softening temperatures and high toughness
Glasses having a low softening point and high toughness. The glasses are alkali aluminoborosilicate glasses having softening points of less than 900° C. and, in some embodiments, in a range from about 650° C. up to about 825° C., and an indenter damage threshold of at least 300 g for glasses that are not chemically strengthened. The glasses are free of alkaline earth metals, lead, arsenic, antimony, and, in some embodiments, lithium.
1. An alkali aluminoborosilicate glass, the glass having a softening point in a range from 650° C. up to 725° C. and an indenter damage threshold of at least 300 g, and wherein the glass has a B 2 O 3 /Al 2 O 3 molar ratio of greater than 1.2 and is free of alkaline earth metals, lead, arsenic, and antimony.
2. The alkali aluminoborosilicate glass of claim 1 , wherein the glass has a surface layer under compressive stress and an indenter damage threshold of at least 3000 g.
3. The alkali aluminoborosilicate glass of claim 2 , wherein the glass has an indenter threshold in a range from about 3000 g up to about 10,000 g.
4. The alkali aluminoborosilicate glass of claim 2 , wherein the surface layer is ion exchanged.
5. The alkali aluminoborosilicate glass of claim 2 , wherein the surface layer has a depth of layer of at least 20 pm and a compressive stress of at least 700 MPa.
6. The alkali aluminoborosilicate glass of claim 1 , wherein the glass comprises: 50-70 mol % SiO 2 ; 5-15 mol % Al 2 O 3 ; 5-20 mol % B 2 O 3 ; 0-15 mol % Li 2 O; 0-20 mol % Na 2 O; and 0-10 mol % K 2 O.
7. The alkali aluminoborosilicate glass of claim 6 , wherein the glass is free of lithium.
8. The alkali aluminoborosilicate glass of claim 6 , wherein the glass consists essentially of: 50-70 mol % SiO 2 ; 5-15 mol % Al 2 O 3 ; 5-20 mol % B 2 O 3 ; 0-15mol % Li 2 O; 0-20 mol % Na 2 O; and 0-10 mol % K 2 O.
9. The alkali aluminoborosilicate glass of claim 1 , wherein the glass is inert with respect to zircon at temperatures at which the viscosity of the glass is at least 5 KP.
10. The alkali aluminoborosilicate glass of claim 1 , wherein the glass has a liquidus viscosity of at least 135 KP.
11. The alkali aluminoborosilicate glass of claim 10 , wherein the glass has a liquidus viscosity of at least 1 MP.
12. The alkali aluminoborosilicate glass of claim 1 , wherein the glass is down-drawable.
13. The alkaline aluminoborosilicate glass of claim 1 , wherein the glass is formed into a glass article, wherein the glass article is one of a display window, a cover plate, a screen, and a structural feature for an electronic device.
14. The alkaline aluminoborosilicate glass of claim 1 , wherein the glass article is non-planar.
15. An alkali aluminoborosilicate glass, the glass having a surface layer under compressive stress, a softening point in a range from about 850° C. up to about_900° C. and an indenter damage threshold of at least 5 kg, and wherein the glass has a R′ 2 O 3 /R 2 O molar ratio in a range from 1.5 up to 1.7 and a molar ratio R 2 O/Al 2 O 3 in a range from 0.95 up to 1.10, where R′ 2 O 3 =Al 2 O 3 +B 2 O 3 and R 2 O =Li 2 O+Na 2 O+K 2 O, and is free of alkaline earth metals, lead, arsenic, and antimony.
16. The alkali aluminoborosilicate glass of claim 15 , wherein the glass comprises: 50-70 mol % SiO 2 ; 5-15 mol % Al 2 O 3 ; 5-20 mol % B 2 O 3 ; 0-15 mol % Li 2 O; 0-20 mol % Na 2 O; and 0-10 mol % K 2 O.
17. The alkali aluminoborosilicate glass of claim 15 , wherein the glass comprises: 50-70 mol % SiO 2 ; 5-15 mol % Al 2 O 3 ; 3-20 mol % B 2 O 3 ; and 10-20mol % Na 2 O.
18. The alkali aluminoborosilicate glass of claim 15 , wherein the glass is free of lithium.
19. The alkali aluminoborosilicate glass of claim 15 , wherein the indenter damage threshold is in a range from 5 kg up to 15 kg.
20. The alkali aluminoborosilicate glass of claim 15 , wherein the surface layer is ion exchanged.
21. The alkali aluminoborosilicate glass of claim 15 , wherein the glass has a liquidus viscosity of at least 1 MP.
22. The alkali aluminoborosilicate glass of claim 15 , wherein the glass is down-drawable.
23. The alkaline aluminoborosilicate glass of claim 15 , wherein the glass is formed into a glass article, wherein the glass article is one of a display window, a cover plate, a screen, and a structural feature for an electronic device.
24. The alkali aluminoborosilicate glass of claim 22 , wherein the glass article is non-planar.
25. The alkali aluminoborosilicate glass of claim 20 , wherein the glass has a damage threshold load of at least about 45 kg.