Glass with compressive surface for consumer applications

• US 8,561,429 B2
• Filed: 07/10/2009
• Issued: 10/22/2013
• Est. Priority Date: 07/11/2008
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Allan, Douglas Clippinger, Ellison, Adam James, Gomez, Sinue
• Primary Examiner(s): WIESE, NOAH S
• Application Number:
  US12/500,650
• Publication Number:
  US 20100009154A1
• Time in Patent Office: 1,565 Days
• Field of Search: 501/66, 501/68, 501/69, 501/70, 501/72, 654/00, 65/301.3, 65/301, 65/301.4
• US Class Current: 65/30.13
• CPC Class Codes: C03C 21/002 to perform ion-exchange between alkali ions C03C21/005 takes precedence
• CPC Class Codes: C03C 3/085 containing an oxide of a divalent metal
• CPC Class Codes: C03C 3/093 containing zinc or zirconium

Abstract

A strengthened glass that does not exhibit frangible behavior when subjected to impact or contact forces, and a method of strengthening a glass. The glass may be strengthened by subjecting it to multiple, successive, ion exchange treatments. The multiple ion exchange treatments provide a local compressive stress maximum at a depth of the strengthened layer and a second local maximum at or near (e.g., within 10 μm) the surface of the glass.

Claims

1. A method of strengthening a glass, the method comprising the steps of:

a. providing the glass, the glass having a surface; and

b. successively immersing at least a portion of the glass in a plurality of ion exchange baths, the ion exchange baths comprising a first ion exchange bath, the first ion exchange bath comprising a first metal, and a second ion exchange bath, the second ion exchange bath comprising a metal that is different from the first metal, to create a compressive stress in an outer region to strengthen the glass, the outer region extending from the surface to a depth of layer, wherein the compressive stress creates an integrated central tension of less than or equal to about 3.2 MPa·

cm in a central tensile region of the glass, wherein each of the plurality of ion exchange baths are at a temperature in a range from about 410°

C. to about 430°

C.

2. The method of claim 1, wherein the depth of layer is at least 50 μ

m.

3. The method of claim 1, wherein the compressive stress is at least about 200 MPa.

4. The method of claim 1, wherein the glass has a liquidus viscosity of at least 130 kilopoise.

5. The method of claim 1, wherein the glass is one of a planar sheet and a three-dimensional curved sheet.

6. The method of claim 5, wherein the glass is one of a cover plate and a display window in an electronic device.

7. The method of claim 1, wherein the successive ion exchange baths have compositions that are different from each other.

8. The method of claim 1, further comprising annealing the glass between successive immersions of the glass in the plurality of ion exchange baths.

9. The method of claim 1, wherein the first metal and second metal are alkali metals.

10. The method of claim 1, wherein each of the plurality of ion exchange baths comprises at least one alkali metal salt.

11. The method of claim 1, wherein the glass is an alkali aluminosilicate glass.

12. The method of claim 11, wherein the alkali aluminosilicate 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; and

less than 50 ppm Sb₂O₃;

wherein 12 mol %≦

Li₂O+Na₂O+K₂O≦

20 mol % and 0 mol %≦

MgO+CaO≦

10 mol %.

13. The method of claim 1, wherein the glass, when strengthened, is substantially free of frangible behavior.