Microwave-based glass laminate fabrication

• US 10,099,954 B2
• Filed: 06/18/2015
• Issued: 10/16/2018
• Est. Priority Date: 07/15/2011
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Godard, Hilary Tony, Peng, Gaozhu, Peterson, Irene Mona, Schulz, Rebecca Lynn, Squier, Gary Graham
• Primary Examiner(s): Abraham, Ibrahime A
• Assistant Examiner(s): Norton, John J
• Application Number:
  US14/743,415
• Publication Number:
  US 20150284282A1
• Time in Patent Office: 1,216 Days
• CPC Class Codes: C03B 13/10 Rolling multi-layer sheets , e.g. sheets having a coloured glass layer
• CPC Class Codes: C03B 17/02 Forming molten glass coated with coloured layers; Forming molten glass of different compositions or layers; Forming molten glass comprising reinforcements or inserts
• CPC Class Codes: C03B 17/064 by the overflow downdraw fusion process; Isopipes therefor
• CPC Class Codes: C03B 17/067 combined with thermal conditioning of the sheets
• CPC Class Codes: C03B 18/12 Making multilayer, coloured or armoured glass chemical aspects C03C
• CPC Class Codes: C03B 23/023 by bending
• CPC Class Codes: C03B 23/0235 involving applying local or additional heating, cooling or insulating means
• CPC Class Codes: C03B 27/012 by heat treatment, e.g. for crystallisation; Heat treatment of glass products before tempering by cooling C03B27/008, C03B27/016 take precedence
• CPC Class Codes: C03C 23/0065 by microwave radiation

Abstract

Methods of fabricating a glass laminate is provided. According to one embodiment, a glass laminate comprised of a microwave absorbing layer and a microwave transparent layer is formed. The microwave absorbing layer is characterized by a microwave loss tangent δ_H that is at least a half order of magnitude larger than a loss tangent δ_L of the microwave transparent layer. An area of the glass laminate is exposed to microwave radiation. The exposed area comprises a cross-laminate hot zone having a cross-laminate hot zone temperature profile. Substantially all microwave absorbing layer portions of the hot zone temperature profile and substantially all microwave transparent layer portions of the hot zone temperature profile reside above the glass transition temperature T_G of the various layers of the glass laminate prior to impingement by the microwave radiation. In accordance with another embodiment, a method of fabricating a glass laminate is provided where the exposed area of the glass laminate is characterized by a viscosity below approximately 1×10⁴ poise.

Claims

1. A method comprising:

contacting a molten microwave absorbing glass with a molten microwave transparent glass in a double isopipe fusion process to form a glass laminate;

exposing an area of the glass laminate to microwave radiation, wherein;

the exposed area of the glass laminate glass is near a bottom core isopipe root of the double isopipe fusion process;

the glass laminate comprises a microwave absorbing layer and a microwave transparent layer, and a microwave loss tangent δ

_H of the microwave absorbing layer is at least a half order of magnitude larger than a microwave loss tangent δ

_L of the microwave transparent layer, at least at one or more temperature points at which the glass laminate exhibits a viscosity of between approximately 1×

10² poise and approximately 1×

10¹³³ poise; and

in the exposed area of the glass laminate, each of the microwave absorbing layer and the microwave transparent layer is at a temperature above a glass transition temperature T_G of the respective layer prior to exposure to the microwave radiation.

2. The method of claim 1, wherein an intensity distribution of the microwave radiation upon impingement with the glass laminate is sufficient to increase a temperature of the microwave absorbing layer to a greater extent than a temperature of the microwave transparent layer.

3. The method of claim 1, wherein the exposed area of the glass laminate comprises a viscosity below approximately 1×

10⁵ poise prior to exposure to the microwave radiation.

4. The method of claim 1, wherein each of the microwave absorbing layer and the microwave transparent layer comprises a viscosity below approximately 1×

10⁵ poise at 1200°

C.

5. The method of claim 1, wherein:

the exposed area of the glass laminate comprises a cross-laminate hot zone having a cross-laminate hot zone temperature profile; and

an intensity distribution of the microwave radiation upon impingement with the glass laminate is sufficient to increase a temperature of the microwave absorbing layer portions of the hot zone temperature profile to a greater extent than a temperature of the microwave transparent layer portions of the hot zone temperature profile.

6. The method of claim 5, wherein the microwave absorbing layer portions of the hot zone temperature profile and the microwave transparent layer portions of the hot zone temperature profile reside above the glass transition temperature T_G of the various layers of the glass laminate.

7. The method of claim 1, wherein, in the exposed area of the glass laminate, each of the microwave absorbing layer and the microwave transparent layer is at a temperature above approximately 900°

C. prior to exposure to the microwave radiation.

8. The method of claim 1, wherein, in the exposed area of the glass laminate, each of the microwave absorbing layer and the microwave transparent layer is at a temperature above a liquidus temperature of the respective layer prior to exposure to the microwave radiation.

9. The method of claim 1, wherein the microwave radiation originates from one or more microwave sources collectively configured with respect to power and frequency for substantially complete cross-laminate penetration of the glass laminate.

10. The method of claim 1, wherein the microwave radiation originates from one or more microwave sources collectively configured with respect to power and frequency for penetration of at least approximately 0.5 mm into the glass laminate.

11. The method of claim 1, wherein the glass laminate comprises a microwave absorbing core layer sandwiched between microwave transparent outer layers or a microwave transparent core layer sandwiched between microwave absorbing outer layers.

12. The method of claim 1, wherein:

the microwave transparent layer comprises a pair of microwave transparent outer layers of the glass laminate; and

the microwave absorbing layer comprises a microwave absorbing core layer sandwiched between the microwave transparent outer layers of the glass laminate.

13. The method of claim 1, wherein:

the microwave transparent layer comprises a pair of microwave transparent outer layers; and

the microwave absorbing layer comprises a microwave absorbing core layer sandwiched between the pair of microwave transparent outer layers.

14. The method of claim 1, wherein:

the microwave absorbing layer is a microwave absorbing glass layer;

the microwave transparent layer is a microwave transparent glass layer; and

the glass laminate comprises the microwave absorbing layer fused to the microwave transparent layer.