GLASS WITH SURFACE AND CENTRAL REGIONS UNDER COMPRESSION

• US 20130236666A1
• Filed: 11/29/2011
• Published: 09/12/2013
• Est. Priority Date: 11/30/2010
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Bookbinder, Dana Craig, Gross, Timothy Michael
• Granted Patent: US 9,193,625 B2
• Time in Patent Office: Days
• US Class Current: 428/34.4
• CPC Class Codes: B32B 17/06 comprising glass as the main or only constituent of a layer, next to another layer of a specific material
• CPC Class Codes: B32B 17/10045 with at least one intermediate layer consisting of a glass sheet
• CPC Class Codes: B32B 17/10137 Chemical strengthening
• CPC Class Codes: C03B 23/203 Uniting glass sheets C03B23/24 takes precedence
• 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 428/131 Glass, ceramic, or sintered, fused, fired, or calcined metal oxide or metal carbide containing [e.g., porcelain, brick, cement, etc.]
• CPC Class Codes: Y10T 428/24992 Density or compression of components

Abstract

A glass article having an engineered stress profile. The central or core region of the glass is in compression and the surface or outer region of the glass is either under neutral stress or in compression. The outer surface region and the core region are separated by an intermediate region that is under tension. A flaw that penetrates the outer region in compression will propagate in the underlying tensile intermediate layer, but will not penetrate though the compressive core region of the glass. The compressive core region prevents flaws from penetrating through the thickness of the glass.

Claims

1. A glass article, the glass article comprising:

a. an outer region extending from the surface to a depth of layer, wherein the outer region is under neutral stress or a first compressive stress;

b. a core region under a second compressive stress; and

c. an intermediate region disposed between the surface and the core region, wherein the intermediate region is under a tensile stress.

3. The glass article of claim 1, wherein the outer region is under the first compressive stress.

4. The glass article of claim 3, wherein the depth of layer of the outer region is at least 5 μ

m.

5. The glass article of claim 3, wherein the first compressive stress is at least 500 MPa.

6. The glass article of claim 3, wherein the glass article has a laminate structure.

7. The glass article of claim 6, wherein:

a. the core region comprises a first glass having a first coefficient of thermal expansion;

b. the intermediate region comprises a second glass having a second coefficient of thermal expansion; and

c. the outer region comprises a third glass having a third coefficient of expansion, and wherein the first coefficient of expansion and third coefficient of thermal expansion are less than the second coefficient of thermal expansion.

8. The glass article of claim 6, wherein:

a. the core region comprises a core glass, the core glass comprising a first alkali metal ion;

b. the intermediate region comprises the core glass and a second alkali metal ion that is smaller than the first alkali metal ion; and

c. the outer region comprises a skin glass, the skin glass comprising a third alkali metal ion, wherein the third alkali metal ion is larger than the second alkali metal ion.

9. The glass article of claim 1, wherein the glass article has a Vickers crack initiation threshold of at least 5000 gf.

10. The glass article of claim 1, wherein the glass article is ion exchanged.

11. The glass article of claim 1, wherein the glass article comprises an alkali aluminosilicate glass or an alkali aluminoborosilicate glass.

12. The glass article of claim 11, where the alkali aluminosilicate glass comprises:

61-75 mol % SiO₂;

7-15 mol % Al₂O₃;

0-12 mol % B₂O₃;

9-21 mol % Na₂O;

0-4 mol % K₂O;

0-7 mol % MgO; and

0-3 mol % CaO.

13. The glass article of claim 11, where 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; and

wherein 12 mol %≦

Li₂O+Na₂O+K₂O≦

20 mol % and 0 mol %≦

MgO+CaO≦

10 mol %.

14. The glass article of claim 11, where the alkali aluminoborosilicate glass comprises:

greater than 50 mol % SiO₂, and wherein the ratio

15. The glass article of claim 1, wherein the glass article comprises SiO₂, Al₂O₃, P₂O₅, and at least one alkali metal oxide (R₂O), wherein 0.75≦

[(P₂O₅ (mol %)+R₂O (mol %))/M₂O₃ (mol %)]≦

1.2, where M₂O₃=Al₂O₃+B₂O₃.

16. The glass article of claim 1, wherein the glass article is a planar sheet.

17. The glass article of claim 16, wherein the planar sheet has a thickness of up to 1.2 mm.

18. The glass article of claim 1, wherein the core region deflects cracks propagating through the intermediate layer by at least 45°

.

19. The glass article of claim 1, wherein the glass article forms at least a portion of:

a touch screen;

a protective cover glass for a hand held electronic device;

an information-related terminal, or a touch sensor device;

a windshield;

an appliance enclosure;

or an architectural panel.

2. (canceled)

20-27. -27. (canceled)

28. A glass article, the glass article having a laminate structure, wherein the laminate structure comprises:

an outer region extending from a surface of the glass article to a depth of layer, wherein the outer region is under neutral stress or a first compressive stress;

a core region under a second compressive stress; and

an intermediate region disposed between the outer region and the core region, wherein the intermediate region is under a tensile stress.

45. A method of making a crack-resistant glass article, the method comprising the steps of:

a. providing a glass article, the glass article having a core region, a surface region, and an intermediate region disposed between the surface region and the core region; and

b. creating a compressive stress in the core region and a tensile stress in the intermediate region, wherein the compressive stress at least partially blocks propagation of cracks from the intermediate region through the core region.

47. The method of claim 45, wherein the steps of exchanging the alkali metal ion in the glass with the second alkali metal ion and the third alkali metal ion comprise exposing the glass article to an ion exchange medium, the ion exchange medium comprising the second alkali metal ion and the third alkali metal ion, wherein the second alkali metal is present in the ion exchange medium in a concentration ion that is greater than that of the third alkali metal ion.

49. The method of claim 47, wherein, the intermediate region comprises an intermediate glass, and wherein the core glass and the skin glass each have a coefficient of thermal expansion that is less than a coefficient of thermal expansion of the intermediate glass.

50. The method of claim 47, wherein the core glass comprises a first alkali metal ion and the skin glass comprises a third alkali metal ion, wherein the first alkali metal ion is larger than the second alkali metal ion, and wherein the step of creating a compressive stress in the core region and a tensile stress in the intermediate region comprises:

a. providing an ion exchange medium comprising a second alkali metal ion;

b. exchanging the second alkali ion in the ion exchange medium for the third alkali metal ion in the skin glass to create a compressive stress in the surface region; and

c. exchanging the second alkali metal ion in the ion exchange medium for the first alkali metal ion in a portion of the core glass adjacent to the surface region to form the intermediate region and to create a compressive stress in the core region and a tensile stress in the intermediate region.