Continuous methods of forming glass ribbon using a gyrotron microwave heating device

Patent metadata

Field	Value
Publication number	US-11739018-B2
Application number	US-202017018231-A
Country	US
Kind code	B2
Filing date	Sep 11, 2020
Priority date	Sep 13, 2019
Publication date	Aug 29, 2023
Grant date	Aug 29, 2023

Abstract

A method of forming a glass ribbon includes flowing a molten glass into a caster having a width (Wcast) and a thickness (Tcast) to form a cast glass, cooling the cast glass in the caster to a viscosity of 108 Poise or more, conveying the cast glass from the caster, volumetrically heating the cast glass to an average viscosity of 106 Poise or less using a gyrotron microwave heating device, and drawing the cast glass into a glass ribbon having a width (Wgr) that is less than or equal to the width (Wcast) of the caster and a thickness (Tgr) that is less than the thickness (Tcast) of the caster.

First claim

What is claimed is:

1. A method of forming a glass ribbon, the method comprising:
flowing a molten glass into a caster having a width (W cast ) and a thickness (T cast ) to form a cast glass;
cooling the cast glass in the caster to a viscosity of 10 8 Poise or more;
conveying the cast glass from the caster;
volumetrically heating the cast glass to an average viscosity of 10 6 Poise or less using a gyrotron microwave heating device; and
drawing the cast glass into a glass ribbon having a width (W gr ) that is less than or equal to the width (W cast ) of the caster and a thickness (T gr ) that is less than the thickness (T cast ) of the caster.

2. The method of claim 1 , wherein, during volumetric heating, the temperature of the cast glass increases at a heating rate of 15° C./second or greater.

3. The method of claim 1 , wherein volumetrically heating the cast glass occurs for a heating period of 0.5 seconds to 10 seconds.

4. The method of claim 1 , wherein, during volumetric heating, the gyrotron microwave heating device generates a microwave beam comprising a power intensity of 1×10 6 W/m 2 or greater.

5. The method of claim 1 , wherein, during volumetric heating, the gyrotron microwave heating device generates a microwave beam comprising a frequency of 10 GHz to 300 GHz.

6. The method of claim 1 , wherein:
the cast glass comprises a first major surface, a second major surface opposite the first major surface, and a glass body extending from the first major surface to the second major surface and comprising a central region disposed equidistant from the first major surface and the second major surface; and
during volumetric heating of the cast glass, a temperature of the central region of the glass body of the cast glass is equal to or greater than a temperature of the first major surface of the cast glass and a temperature of the second major surface of the cast glass.

7. The method of claim 6 , wherein, during volumetric heating, the central region of the cast glass reaches a temperature of 750° C. or greater.

8. The method of claim 1 , wherein during volumetric heating, the gyrotron microwave heating device generates a microwave beam and a cross section of the microwave beam comprises a width that is greater than the width (W cast ) of the caster.

9. The method of claim 1 , wherein the width (W cast ) of the caster is from 100 mm to 1 m and the thickness (T cast ) of the caster is from 10 mm to 50 mm.

10. The method of claim 1 , wherein, when conveyed from the caster, the cast glass comprises a thickness (T cg ) of 12 mm or greater.

11. The method of claim 1 , wherein the cast glass is cooled in the caster to a temperature of 700° C. or less and no lower than 50° C.

12. The method of claim 1 , wherein a maximum crystal growth rate of any crystalline phase of the cast glass is from 0.01 μm/min to 10 μm/min.

13. The method of claim 1 , wherein the molten glass flowing into the caster comprises a borosilicate glass, an aluminoborosilicate glass, an aluminosilicate glass, a fluorosilicate glass, a phosphosilicate glass, a fluorophosphate glass, a sulfophosphate glass, a germanate glass, a vanadate glass, a borate glass, or a phosphate glass.

14. The method of claim 1 , wherein the molten glass flowing into the caster comprises a viscosity of 5×10 4 Poise or less and a temperature of 1000° C. or greater.

15. The method of claim 1 , wherein:
the thickness (T gr ) of the glass ribbon is from 0.3 mm to 1 mm;
the glass ribbon comprises a refractive index of from 1.6 to 1.9; and
the glass ribbon comprises a thickness variation from 0.01 μm to 50 μm and a warp from 0.01 μm to 100 μm.

Assignees

• Corning Inc

Inventors

• Hoque Aziz
• Yu Chao

Classifications

• C03B17/067 Primary

  combined with thermal conditioning of the sheets · CPC title

• C03B17/064

  by the overflow downdraw fusion process; Isopipes therefor · CPC title

• C03B19/02 Primary

  by casting {molten glass, e.g. injection moulding} · CPC title

• C03B17/06 Primary

  Forming glass sheets · CPC title

• C03B15/02

  Drawing glass sheets · CPC title