Fictive temperature in damage-resistant glass having improved mechanical characteristics

Patent metadata

Field	Value
Publication number	US-9802853-B2
Application number	US-201514814293-A
Country	US
Kind code	B2
Filing date	Jul 30, 2015
Priority date	Jul 31, 2014
Publication date	Oct 31, 2017
Grant date	Oct 31, 2017

Abstract

A strengthened glass sheet product as well as process and an apparatus for making 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 first major surface of the sheet being flat to 100 μm total indicator run-out (TIR) along any 50 mm or less profile of the first major surface
the glass sheet comprising a glass having a softening temperature, expressed in units of ° C., of T soft and an annealing temperature, expressed in units of ° C., of T anneal , and a surface fictive temperature measured on the first major surface of the glass sheet represented by Tfs, when expressed in units of ° C.;
the glass sheet having a non-dimensional surface fictive temperature parameter θs given by (Tfs−T anneal )/(T soft −T anneal ),
wherein the parameter θs is in the range of from 0.50 to 0.9.

2. The glass sheet according to claim 1 wherein the parameter θs is in the range of from 0.51 to 0.9.

3. The glass sheet according to claim 1 wherein the parameter θs is in the range of from 0.52 to 0.9.

4. The glass sheet according to claim 1 wherein the parameter θs is in the range of from 0.60 to 0.9.

5. The glass sheet according to claim 1 , l and w each being at least 10 mm.

6. The glass sheet according to claim 5 , wherein the ratio l/t and the ratio w/t each are equal to 10/1 or more.

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

8. The glass sheet according to claim 6 wherein the first major surface has a roughness in the range of from 0.2 to 1.5 nm Ra over an area of 10×10μ.

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

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

11. The glass sheet according to claim 1 wherein t is 0.7 mm or less.

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

13. 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.

14. The glass sheet according to claim 1 , wherein the compressive stress of said first major surface is larger than 150 MPa.

15. The glass sheet according to claim 1 , wherein the central tension of the sheet is larger than 75 MPa.

16. The glass sheet according to claim 15 wherein the surface fictive temperature measured on the first surface of the sheet is at least 50° C. above a glass transition temperature of the glass.

17. The glass sheet according to claim 15 wherein the surface fictive temperature measured on the first surface of the sheet is at least 75° C. above a glass transition temperature of the glass.

18. The glass sheet according to claim 1 , l and w each being at least 40 mm.

19. The glass sheet according to claim 1 , wherein the ratio l/t and the ratio w/t each are equal to 20/1 or more.

20. The glass sheet according to claim 1 , wherein the ratio l/t and the ratio with each are equal to 100/1 or more.

21. The glass sheet according to claim 1 wherein t is 1 mm or less.

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

23. The glass sheet according to claim 1 wherein the sheet exhibits a 50% cracking threshold at 10 Newtons or greater after a 15 second Vickers Hardness Test.

24. The glass sheet according to claim 1 , wherein the compressive stress of said first major surface is larger than 80 MPa.

25. The glass sheet according to claim 1 , wherein the compressive stress of said first major surface is larger than 100 MPa.

26. The glass sheet according to claim 1 , wherein the central tension of the sheet is larger than 40 MPa.

27. The glass sheet according to claim 1 , wherein the central tension of the sheet is larger than 50 MPa.

28. 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 first major surface of the sheet being flat to 100 μm total indicator run-out (TIR) along any 50 mm or less profile of the first major surface
the glass sheet comprising a glass having a softening temperature, expressed in units of ° C., of T soft and an annealing temperature, expressed in units of ° C., of T anneal , and a surface fictive temperature measured on the first major surface of the glass sheet represented by Tfs, when expressed in units of ° C.;
the glass sheet having a non-dimensional surface fictive temperature parameter θs given by (Tfs−T anneal )/(T soft −T anneal ),
wherein the parameter θs is in the range of from 0.50 to 0.9; and
wherein the glass has 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, and a strain temperature, expressed in units of ° C., of T strain ;
the first major surface of the glass sheet having a thermally induced surface compressive stress of less than 600 MPa and greater than

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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

• C03B27/048

  on a gas cushion · CPC title

• Y10T428/315

  Surface modified glass [e.g., tempered, strengthened, etc.] · CPC title

• C03B27/052

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