Method of strengthening glass using plasma torches and/or arc jets, and articles made according to the same

• US 20130059087A1
• 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 9,604,877 B2
• Time in Patent Office: Days
• US Class Current: 427/446
• CPC Class Codes: C03C 21/007 in gaseous phase
• CPC Class Codes: C03C 23/0055 by ion implantation
• CPC Class Codes: C03C 23/006 by plasma or corona discharge
• CPC Class Codes: C03C 25/607 in the gaseous phase
• CPC Class Codes: C03C 25/6286 Ion implantation
• CPC Class Codes: C23C 14/48 Ion implantation
• CPC Class Codes: C23C 16/513 using plasma jets
• CPC Class Codes: H01J 2237/327 Arrangements for generating the plasma
• CPC Class Codes: H01J 37/32018 Glow 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:

disposing at least one plasma torch comprising at least first and second electrodes on at least a first major surface of a glass substrate; and

spraying a plasma comprising replacement ions through a nozzle of the plasma torch via an applied electric field between the two electrodes such that the plasma is sprayed proximate the first major surface of the glass substrate;

wherein the replacement ions are driven into the at least one major surface of the glass substrate so as to increase the strength of the glass substrate.

2. The method of claim 1, further comprising:

disposing a second plasma torch comprising third and fourth electrodes on a second major surface of a glass substrate; and

spraying a plasma comprising replacement ions through a nozzle of the second plasma torch via an applied electric field between the two electrodes such that the plasma is sprayed proximate the second major surface of the glass substrate,

wherein the replacement ions are driven into the first and second major surfaces of the glass substrate so as to increase the strength of the glass substrate.

3. The method of claim 1, wherein the replacement ions are divalent.

4. The method of claim 1, wherein the replacement ions are multivalent.

5. The method of claim 1, wherein the ions are driven into the first major surface of the glass substrate to a depth of at least about 100 micrometers.

6. The method of claim 5, wherein the ions are driven to said depth in about 10 minutes or less.

7. The method of claim 6, wherein the ions are driven to said depth in about 5 minutes or less.

8. The method of claim 1, wherein the glass substrate has a strength of at least about 400 MPa.

9. The method of claim 8, wherein said strength of the glass substrate is reached in about 10 minutes or less.

10. The method of claim 8, wherein the glass substrate has a strength of at least about 600 MPa.

11. The method of claim 1, wherein the glass substrate comprises soda lime silica glass.

12. A method for strengthening a soda lime silica glass substrate, the method comprising:

disposing first and second plasma torches or arc jets on opposing major surfaces of a glass substrate;

spraying a plasma comprising replacement ions onto the opposing major surfaces of the glass substrate via each plasma torch or arc jet;

driving the replacement ions into the first and second major surfaces of the glass substrate by virtue of electric fields between the first and second electrodes of each plasma torch or arc jet, so as to increase the strength of the glass substrate.

13. The method of claim 12, wherein the electric field has a magnitude of at least about 50 V/mm.

14. The method of claim 12, wherein the electric field has a magnitude of at least about 100 V/mm.

15. The method of claim 12, wherein the replacement ions comprise at least one of Li⁺, K⁺ and Mg²⁺.

16. The method of claim 12, wherein the replacement ions are driven at least 100 microns into surface regions of the glass substrate.

17. The method of claim 12, wherein at least some of the sodium ions between the surface of the glass substrate and a depth of 100 microns into the glass substrate are replaced with the replacement ions.

18. The method of claim 12, wherein the replacement ions are divalent and/or multivalent.

19. The method of claim 12, wherein the glass substrate has a strength of at least about 400 MPa in about 5 minutes or less.

20. A method of making a glass substrate, the method comprising:

exposing opposing major surfaces of a soda lime silica glass substrate to plasmas containing ions, the soda lime silica glass substrate at least initially including 10-20 wt. % Na₂O; and

selectively activating electrodes associated with the plasma to drive the ions, directly or indirectly, into surface regions of the glass substrate and force sodium ions out from the surface regions to reduce Na₂O content of the glass substrate to less than 10 wt. %.