Chemically strengthenable lithium aluminosilicate glasses with inherent damage resistance
A group of glass compositions in the Li 2 O—Al 2 O 3 —SiO 2 —B 2 O 3 family that can be chemically strengthened in single or multiple ion exchange baths containing at least one of NaNO 3 and KNO 3 for a short time (2-4 hours) to develop a deep depth of layer (DOL). In some instances, the DOL is at least 70 μm; in others, at least about 100 μm. The ion exchanged glasses have a high damage resistance (indentation fracture toughness ranging form greater than 10 kgf to greater than 50 kgf) that is better than or at least comparable to that of sodium aluminosilicate glasses.
1. A lithium aluminosilicate glass article, wherein the lithium aluminosilicate glass article is formed from a glass comprising:
from 55 mol % to 75 mol % SiO 2 ,
from 10 mol % to 18 mol % Al 2 O 3 ,
from 7 mol % to 14 mol % Li 2 O,
from 0.2 mol % to 5 mol % Na 2 O,
from 0 mol % to 1 mol % K 2 O,
from 3 mol % to 7 mol % B 2 O 3 , and
from 0 mol % to 1 mol % P 2 O 5 ,
wherein R 2 O (mol %)+R′O (mol %)−Al 2 O 3 (mol %)−B 2 O 3 (mol %)−P 2 O 5 (mol %) is in a range from −10.5 mol % to −0.11 mol %, where R 2 O=Li 2 O+Na 2 O+K 2 O+Rb 2 O+Cs 2 O and R′O=MgO+CaO+SrO+BaO.
2. The lithium aluminosilicate glass article of claim 1 , wherein the glass comprises:
from 57 mol % to 67 mol % SiO 2 .
3. The lithium aluminosilicate glass article of claim 1 , wherein the glass comprises:
from 12 mol % to 18 mol % Al 2 O 3 .
4. The lithium aluminosilicate glass article of claim 1 , wherein the glass comprises:
from 7 mol % to 12.6 mol % Li 2 O.
5. The lithium aluminosilicate glass article of claim 1 , wherein the glass comprises:
from 7 mol % to 10 mol % Li 2 O.
6. The lithium aluminosilicate glass article of claim 1 , wherein the glass comprises:
from 3.5 mol % to 7 mol % B 2 O 3 .
7. The lithium aluminosilicate glass article of claim 1 , wherein the glass from which the lithium aluminosilicate glass article is formed is characterized by R 2 O (mol %)−Al 2 O 3 (mol %) is in a range from −2 mol % to 5.6 mol %.
8. The lithium aluminosilicate glass article of claim 1 , wherein the glass from which the lithium aluminosilicate glass article is formed is characterized by (Al 2 O 3 (mol %)+B 2 O 3 (mol %))/R 2 O (mol %) is in a range from 0.9 to 1.9.
9. The lithium aluminosilicate glass article of claim 1 , wherein (Al 2 O 3 (mol %)+B 2 O 3 (mol %))/R 2 O (mol %) is in a range from 1.13 to 1.9.
10. The lithium aluminosilicate glass article of claim 1 , wherein the glass is characterized by
Al 2 O 3 (mol %)>B 2 O 3 (mol %).
11. The lithium aluminosilicate glass of claim 1 , wherein the glass comprises:
from 0 mol % to 1 mol % TiO 2 .
12. The lithium aluminosilicate glass of claim 1 , wherein the glass comprises:
from 0 mol % to 2 mol % ZnO.
13. The lithium aluminosilicate glass of claim 1 , wherein the glass is free of As 2 O 3 and Sb 2 O 3 .
14. The lithium aluminosilicate glass article of claim 1 , wherein the glass from which the lithium aluminosilicate glass article is formed has a liquidus viscosity of at least 10 kP.
15. The lithium aluminosilicate glass article of claim 1 , wherein the lithium aluminosilicate glass has a softening point of 840° C. or less.
16. The lithium aluminosilicate glass article of claim 1 , wherein the glass from which the lithium aluminosilicate glass article is formed has an annealing point of at least 510° C.
17. The lithium aluminosilicate glass article of claim 1 , wherein the glass from which the lithium aluminosilicate glass article is formed has an elastic modulus of at least 68 GPa.
18. The lithium aluminosilicate glass article of claim 1 , wherein the glass is ion exchanged and has a compressive stress layer with a maximum compressive stress of at least 600 MPa.
19. The lithium aluminosilicate glass article of claim 18 , wherein the glass exhibits:
a Vickers crack initiation threshold of at least 10 kgf;
a Knoop scratch threshold of at least 8 N; or
both.
20. A consumer electronic product, comprising:
a housing having a front surface, a back surface and side surfaces;
electrical components provided at least partially within the housing, the electrical components including at least a controller, a memory, and a display, the display being provided at or adjacent the front surface of the housing; and
a cover glass disposed over the display,
wherein at least one of a portion of the housing or the cover glass comprises the lithium aluminosilicate glass article of claim 1 .