GLASS SHEET

• US 20130183512A1
• Filed: 09/12/2011
• Published: 07/18/2013
• Est. Priority Date: 09/13/2010
• Status: Active Grant

• Current Assignee: Saint-Gobain Glass France (Compagnie De Saint-Gobain)
• Original Assignee: Saint-Gobain Glass France (Compagnie De Saint-Gobain)
• Inventors: Sellier, Julien, Gy, Ren, Obame, Hugues
• Granted Patent: US 9,604,876 B2
• Time in Patent Office: Days
• US Class Current: 428/220
• CPC Class Codes: C03C 21/002 to perform ion-exchange between alkali ions C03C21/005 takes precedence
• CPC Class Codes: G01N 2203/0098 Tests specified by its name, e.g. Charpy, Brinnel, Mullen
• CPC Class Codes: G01N 3/20 by applying steady bending forces G01N3/26, G01N3/28 take precedence
• CPC Class Codes: G01N 3/42 by performing impressions under a steady load by indentors, e.g. sphere, pyramid G01N3/54 takes precedence
• CPC Class Codes: Y10T 428/315 Surface modified glass [e.g., tempered, strengthened, etc.]

Abstract

A glass sheet, the thickness of which is at most 2 mm, including a surface zone under compression and a central zone under tension, such that the depth at which the transition between compression and tension occurs is at least 100 micrometers, the ratio between the depth and the thickness being at least 0.1, the sheet additionally being such that the flexural stress at break in a “ring-on-tripod” test is at least 70 MPa, after Vickers indentation under a load of 60 N.

Claims

1. A glass sheet, the thickness of which is at most 2 mm, comprising a surface zone under compression and a central zone under tension, such that a depth at which the transition between compression and tension occurs is at least 100 micrometers, a ratio between said depth and said thickness being at least 0.1, said sheet additionally being such that a flexural stress at break in a “

ring-on-tripod”

test is at least 70 MPa, after Vickers indentation under a load of 60 N.

2. The glass sheet as claimed in claim 1, wherein the surface zone under compression has been obtained by ion exchange.

3. The glass sheet as claimed in claim 1, the thickness of which is at most 1.1 mm and at least 0.25 mm.

4. The glass sheet as claimed in claim 1, wherein the depth at which the transition between compression and tension occurs is at least 200 micrometers and at most 500 micrometers.

5. The glass sheet as claimed in claim 1, wherein a profile of the stresses in the thickness of the glass sheet is such that the maximum compressive stress is at least 70 MPa, a zone subjected to the maximum compressive stress being located at a non-zero distance from the surface of the glass sheet.

6. The glass sheet as claimed in claim 1, wherein a profile of the stresses in the thickness of the glass sheet is such that in a central zone occupying the third of the thickness of the glass, the relative variation of the intensity of the tensile stress is at least 10%.

7. The glass sheet as claimed in claim 5, wherein the ratio between the depth at which the transition between compression and tension occurs and the thickness is at least 0.2 and at most 0.4.

8. The glass sheet as claimed in claim 1, wherein the parameter K is at most 1.4 MPa·

m^1/2, K being the square root of the integral in the central zone under tension of the square of the stress.

9. The glass sheet as claimed in claim 1, wherein the glass is of lithium or sodium aluminosilicate type.

10. The glass sheet as claimed in claim 9, wherein a chemical composition of said glass sheet comprises the following oxides in the ranges of weight contents defined below:

11. The glass sheet as claimed in claim 9, wherein the chemical composition of said glass sheet comprises the following oxides in the ranges of weight contents defined below:

12. An electronic device comprising at least one glass sheet as claimed in claim 1, as protective glass, viewing window, screen or decorative element.

13. A solar, thermal or photovoltaic sensor, comprising at least one glass sheet as claimed in claim 1.

14. A process for obtaining a glass sheet as claimed in claim 1, comprising glass melting, forming, cutting and ion exchange steps.

15. The process as claimed in claim 14, comprising carrying out at least one ion exchange using a molten potassium and/or sodium salt chosen from nitrates, sulfates, chlorides or any mixture thereof.

16. The process as claimed in claim 15, wherein an exchange temperature is at least 450°

C.

17. The glass sheet as claimed in claim 8, wherein the parameter K is at most 1.3 MPa·

m^1/2.

18. The glass sheet as claimed in claim 10, wherein said chemical composition comprises the following oxides in the ranges of weight contents defined below:

19. The glass sheet as claimed in claim 11, wherein the chemical composition comprises the following oxides in the ranges of weight contents defined below:

20. The electronic device as claimed in claim 12, wherein said electronic device is a pocket or portable device.

21. The electronic device as claimed in claim 20, wherein the pocket or portable device is a smartphone, a personal digital assistant, a digital camera, a multimedia player, a computer, a tablet, or a television.

22. The electronic device as claimed in claim 16, wherein the exchange temperature is at least 480°

C.