Method of strengthening glass by plasma induced ion exchanges, and articles made according to the same

• US 20130059160A1
• Filed: 09/02/2011
• Published: 03/07/2013
• Est. Priority Date: 09/02/2011
• Status: Active Grant

• Current Assignee: Guardian Glass LLC (KOCH Industries Incorporated)
• Original Assignee: Guardian Industries Corporation (KOCH Industries Incorporated)
• Inventors: Veerasamy, Vijayen S., Hu, Xuequn, Cerny, Glenn A.
• Granted Patent: US 9,051,214 B2
• Time in Patent Office: Days
• US Class Current: 428/428
• CPC Class Codes: C03C 21/007 in gaseous phase
• CPC Class Codes: C03C 23/006 by plasma or corona discharge

Abstract

Certain example embodiments relate to an improved method of strengthening glass substrates (e.g., soda lime silica glass substrates). In certain examples, a glass substrate may be chemically strengthened by creating an electric field within the glass. In certain cases, the chemical tempering may be performed by surrounding the substrate by a plasma including certain ions, such as Li⁺, K⁺, Mg²⁺, and/or the like. In some cases, these ions may be forced into the glass substrate due to the half-cycles of the electric field generated by the electrodes that formed the plasma. This may advantageously chemically strengthen a glass substrate on a substantially reduced time scale. In other example embodiments, an electric field may be set in a float bath such that sodium ions are driven from the molten glass ribbon into the tin bath, which may advantageously result in a stronger glass substrate with reduced sodium content.

Claims

1. A method for increasing the strength of a glass substrate, the method comprising:

striking a plasma using at least one plasma source and first and second electrodes disposed on opposing major surfaces of a glass substrate, wherein the plasma comprises replacement ions;

driving the replacement ions into the opposing major surfaces of the glass substrate so as to increase the strength of the glass substrate.

2. The method of claim 1, wherein the replacement ions comprise at least one of Li+, K+ and Mg2+.

3. The method of claim 1, wherein the replacement ions replace at least some sodium ions in the glass substrate.

4. The method of claim 1, wherein the glass substrate has a strength of from about 200 to 800 MPa.

5. The method of claim 4, wherein the glass substrate reaches said strength in about 1 to 20 minutes.

6. The method of claim 1, wherein the electrodes directly contact the respective major surfaces of the glass substrate.

7. The method of claim 1, wherein the electrodes are spaced apart from the respective major surfaces of the glass substrate.

8. The method of claim 1, wherein the replacement ions penetrate the surfaces of the glass substrate to a depth of at least about 7 microns.

9. The method of claim 1, wherein the replacement ions penetrate the surfaces of the glass substrate to a depth of at least about 15 microns.

10. The method of claim 1, wherein the replacement ions penetrate the surfaces of the glass substrate to a depth of at least about 50 microns.

11. The method of claim 4, wherein the glass substrate reaches said strength in about 1 to 10 minutes.

12. The method of claim 1, wherein the replacement ions substantially, replace sodium ions proximate the surface(s) of the glass substrate.

13. The method of claim 1, wherein the glass substrate at least initially comprises soda lime silica glass.

14. A method of using plasma to strengthen a glass substrate comprising sodium ions, the method comprising:

striking a plasma using at least one plasma source and first and second electrodes disposed on opposing major surfaces of a glass substrate, wherein the plasma comprises positive ions;

using an electric field to drive the positive ions into the at least one major surface of the glass substrate so as to replace at least some of the sodium ions and increase the strength of the glass substrate.

15. The method of claim 14, wherein the positive ions comprise an alkali metal.

16. The method of claim 14, wherein the positive ions comprise at least one of potassium, lithium and magnesium.

17. The method of claim 14, wherein the electric field is at least about 50 V/mm.

18. The method of claim 14, wherein the electric field is at least about 100 V/mm.

19. The method of claim 14, further comprising scanning the electrodes over the surfaces of the substrate in x and/or y directions.

20. The method of claim 14, wherein the glass substrate reaches a strength of at least about 400 MPa in about 1 to 10 minutes.

21. The method of claim 20, wherein the glass substrate reaches said strength in about 5 minutes or less.

22. The method of claim 14, wherein the electric field is set up in the glass substrate.

23. A chemically-strengthened glass article comprising soda lime silica glass, the article comprising:

at least one of potassium, lithium and magnesium plasma-implanted replacement ions in a surface region of the glass article, wherein the surface region extends from a major surface of the glass article to a depth of at least about 50 microns;

wherein at least some of the replacement ions have replaced sodium ions such that the glass article has fewer sodium ions than a glass article that has not been chemically strengthened; and

wherein the glass article has a strength of at least about 400 MPa.