ION EXCHANGED, FAST COOLED GLASSES

• US 20090220761A1
• Filed: 02/26/2009
• Published: 09/03/2009
• Est. Priority Date: 02/29/2008
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Ellison, Adam James, Dejneka, Matthew John, Gomez, Sinue
• Granted Patent: US 8,232,218 B2
• Time in Patent Office: Days
• US Class Current: 428/220
• CPC Class Codes: C03B 17/067 combined with thermal conditioning of the sheets
• CPC Class Codes: C03B 27/04 using gas
• CPC Class Codes: C03C 21/002 to perform ion-exchange between alkali ions C03C21/005 takes precedence
• CPC Class Codes: C03C 3/083 containing aluminium oxide or an iron compound
• CPC Class Codes: Y10T 428/315 Surface modified glass [e.g., tempered, strengthened, etc.]

Abstract

A glass that is ion exchangeable to a depth of at least 20 μm (microns) and has a internal region having a tension of less than or equal to 100 MPa. The glass is quenched or fast cooled from a first temperature above the anneal point of the glass to a second temperature that is below the strain point of the glass. In one embodiment, the glass is a silicate glass, such as an alkali silicate glass, an alkali aluminosilicate glass, an aluminosilicate glass, a borosilicate glass, an alkali aluminogermanate glass, an alkali germanate glass, an alkali gallogermanate glass, and combinations thereof.

Claims

1. A glass article, the glass article having an anneal point and a strain point, wherein the glass article is quenched from a first temperature that is greater than the anneal point of the glass article to a second temperature, wherein the second temperature is less than the strain point of the glass article, wherein the glass article is ion exchangeable, and wherein the glass article, when ion exchanged, has an ion exchanged surface region having a depth of at least 20 μ

m.

2. The glass article according to claim 1, wherein the glass article, when ion exchanged, has a central tension of less than about 100 MPa.

3. The glass according to claim 1, wherein the glass article is quenched from the first temperature to the second temperature at a rate of at least 4°

C./s.

4. The glass article according to claim 1, wherein the glass article is one of a silicate glass article, an alkali aluminosilicate glass article, an aluminosilicate glass article, a borosilicate glass article, an alkali aluminogermanate glass article, an alkali germanate glass article, an alkali gallogermanate glass article, and combinations thereof.

5. The glass article according to claim 4, wherein the glass comprises:

60-70 mol % SiO₂;

6-14 mol % Al₂O₃;

0-15 mol % B₂O₃;

0-15 mol % Li₂O;

0-20 mol % Na₂O;

0-10 mol % K₂O;

0-8 mol % MgO;

0-10 mol % CaO;

0-5 mol % ZrO₂;

0-1 mol % SnO₂;

0-1 mol % CeO₂;

less than 50 ppm As₂O₃;

less than 50 ppm Sb₂O₃;

wherein 12 mol %≦

Li₂O+Na₂O+K₂O≦

20 mol % and 0 mol %≦

MgO+CaO≦

10 mol %.

6. The glass article according to claim 5, wherein the glass is substantially free of lithium.

7. The glass article according to claim 5, wherein the glass is substantially free of at least one of antimony, barium, and arsenic.

8. The glass article according to claim 1, wherein the wherein the glass article is a glass sheet having a thickness ranging from about 0.1 mm up to about 3 mm.

9. The glass article according to claim 5, wherein the glass sheet is down-drawn.

10. The glass article according to claim 1, wherein the glass sheet is a cover plate for a portable electronic device.

11. The glass article according to claim 1, wherein the glass article is ion exchanged.

12. The glass article according to claim 12, wherein the ion exchanged surface region has a surface compressive stress of at least about 200 MPa.

13. A silicate glass, the silicate glass having an ion exchanged surface region and an internal region, the internal region having a central tension of less than about 100 MPa, and the ion exchanged region having a depth of at least about 20 μ

m.

14. The silicate glass according to claim 13, wherein the ion exchange surface region has a compressive stress of at least about 200 MPa.

15. The silicate glass according to claim 13, wherein the silicate glass is one of an alkali silicate glass, an alkali aluminosilicate glass, an aluminosilicate glass, a borosilicate glass, an alkali aluminogermanate glass, an alkali germanate glass, an alkali gallogermanate glass, and combinations thereof.

16. The silicate glass according to claim 15, wherein the silicate glass comprises:

60-70 mol % SiO₂;

6-14 mol % Al₂O₃;

0-15 mol % B₂O₃;

0-15 mol % Li₂O;

0-20 mol % Na₂O;

0-10 mol % K₂O;

0-8 mol % MgO;

0-10 mol % CaO;

0-5 mol % ZrO₂;

0-1 mol % SnO₂;

0-1 mol % CeO₂;

less than 50 ppm As₂O₃;

less than 50 ppm Sb₂O₃;

wherein 12 mol %≦

Li₂O+Na₂O+K₂O≦

20 mol % and 0 mol %≦

MgO+CaO≦

10 mol %.

17. The silicate glass according to claim 13, wherein the silicate glass is down-drawn.

18. A method of making a silicate glass article, the glass article having an anneal point and a strain point, wherein the glass article has an ion exchanged surface region having a depth of at least 20 μ

m, the method comprising the steps of;

a. providing a glass article;

b. heating the glass article up to a first temperature that is greater than the anneal point of the glass article;

c. quenching the glass article from the first temperature to a second temperature, wherein the second temperature is less than the strain point of the glass article; and

d. forming an ion exchanged surface layer having a depth of at least 20 μ

m in the glass article.

19. The method according to claim 18, wherein the step of quenching the glass article from the first temperature to the second temperature comprises quenching the glass article at a rate of at least 4°

C./s from the first temperature to a second temperature.

20. The method according to claim 18, wherein the step of providing a glass article comprises providing a glass melt.

21. The method according to claim 20, wherein the step of quenching the glass article from the first temperature to the second temperature comprises down-drawing the glass melt to form a sheet of glass.

22. The method according to claim 18, wherein the silicate glass is one of an alkali silicate glass, an alkali aluminosilicate glass, an aluminosilicate glass, a borosilicate glass, an alkali aluminogermanate glass, an alkali germanate glass, an alkali gallogermanate glass, and combinations thereof.

24. The method according to claim 19, wherein the first alkali metal and the second alkali metal are alkali metals other than lithium ions.

23. A method of strengthening a alkali silicate glass without inducing frangibility of the glass article, the method comprising the steps of:

a. providing a glass article, wherein the glass article has an anneal point and a strain point;

b. heating the glass article to a first temperature above the anneal point of the glass, wherein heating the glass article above the anneal point increases the volume of the glass;

c. quenching the glass article from the first temperature to a second temperature below the strain point of the glass article at a predetermined rate and

d. exchanging a plurality of ions of a first alkali metal in the glass article with a plurality of ions second of a second alkali metal, wherein each of the plurality of ions of the second alkali metal has an ionic radius greater than that of each of the plurality of ions of the first alkali metal to create a surface compressive stress profile in the glass article.

25. The method according to claim 23, wherein the glass article is quenched from the first temperature to the second temperature at a rate of at least 4°

C./s.