Highly strengthened glass article

Patent metadata

Field	Value
Publication number	US-9776905-B2
Application number	US-201514814274-A
Country	US
Kind code	B2
Filing date	Jul 30, 2015
Priority date	Jul 31, 2014
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

A strengthened glass sheet product as well as process and an apparatus for producing the product. The process comprises cooling the glass sheet by non-contact thermal conduction for sufficiently long to fix a surface compression and central tension of the sheet. The process results in thermally strengthened glass sheets having improved breakage properties.

First claim

What is claimed is:

1. A thermally strengthened glass sheet:
the glass sheet having a thickness, expressed in millimeters, of t, a length, expressed in millimeters, of l, and a width, expressed in millimeters, of w, t being less than l and less than w;
the glass sheet having a first major surface and a second major surface separated by the thickness t;
the glass sheet comprising a glass having a low temperature linear CTE, expressed in 1/° C., of α S CTE , a high temperature linear CTE, expressed in 1/° C., of α L CTE , an elastic modulus, expressed in GPa, of E, a strain temperature, expressed in units of ° C., of T strain , and a softening temperature, expressed in units of ° C., of T soft ;
the first major surface of the glass sheet having a roughness in the range of from 0.2 to 0.7 nm Ra over an area of 10 μm×10 μm and a thermally induced surface compressive stress of less than 800 MPa and greater than

P
1

⁡

(
h
)

*
t

(

P
2

⁡

(
h
)

+
t

)

·
E
·

[

T
strain

·

α
CTE
s

+

α
CTE
L

·

(

T
soft

-

T
strain

)

]

;

in units of MPa;
wherein P 1 is given by

910.2
-

259.2
·

exp
⁡

(

-

h
0.143

)

;

P 2 is given by

2.53
+

23.65

(

1
+

(

h
0.00738

)

1.58

)

;

and h is a constant greater than or equal to 0.0625.

2. The glass sheet according to claim 1 wherein h is greater than or equal to 0.063.

3. The glass sheet according to claim 1 wherein h is greater than or equal to 0.065.

4. The glass sheet according to claim 1 wherein h is greater than or equal to 0.07.

5. The glass sheet according to claim 1 wherein h is greater than or equal to 0.075.

6. The glass sheet according to claim 1 wherein h is greater than or equal to 0.08.

7. The glass sheet according to claim 1 wherein h is greater than or equal to 0.10.

8. The glass sheet according to claim 1 wherein h is greater than or equal to 0.15.

9. The glass sheet according to claim 6 , l and w each being at least 10.

10. The glass sheet according to claim 9 , wherein the ratio l/t and the ratio w/t each are equal to 10/1 or more.

11. The glass sheet according to claim 1 wherein the first major surface of the sheet is flat to 100 μm total indicator run-out (TIR) along any 50 mm or less profile of the first major surface.

12. The glass sheet according to claim 1 wherein the first major surface has a roughness in the range of from 0.2 to 0.4 nm Ra over an area of 10 μm×10 μm.

13. The glass sheet according to claim 12 wherein the first major surface has a roughness in the range of from 0.2 to 0.3 nm Ra over an area of 10 μm×10 μm.

14. The glass sheet according to claim 1 wherein the first major surface has a coating.

15. The glass sheet according to claim 1 wherein t is less than 2.

16. The glass sheet according to claim 13 wherein t is 1 or less.

17. The glass sheet according to claim 1 wherein t is 0.5 or less.

18. The glass sheet according to claim 1 wherein t is 0.28 or less.

19. The glass sheet according to claim 1 wherein the sheet exhibits a 50% cracking threshold at 5 Newtons or greater after a 15 second Vickers Hardness Test.

20. A thermally strengthened glass sheet according to claim 1 wherein the sheet has a thermally induced central tension less than 400 MPa and greater than

P

1
⁢
CT

⁡

(

h
CT

)

*
t

2
⁢

(

P

Assignees

• Corning Inc

Inventors

• Maschmeyer Richard Orr
• Thomas John Christopher
• Wasson Kevin Lee

Classifications

• B60J1/001

  Double glazing for vehicles · CPC title

• B32B17/10036

  comprising two outer glass sheets · CPC title

• C03B27/012 Primary

  by heat treatment, e.g. for crystallisation; Heat treatment of glass products before tempering by cooling (C03B27/008, C03B27/016 take precedence) · CPC title

• C03B27/0526

  Stresses, e.g. patterns, values or formulae · CPC title

• C03B27/044

  for flat or bent glass sheets being in a horizontal position · CPC title