Thin safety glass having improved mechanical characteristics

• US 10,077,204 B2
• Filed: 07/30/2015
• Issued: 09/18/2018
• Est. Priority Date: 07/31/2014
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Maschmeyer, Richard Orr, Thomas, John Christopher, Wasson, Kevin Lee
• Primary Examiner(s): Handville, Brian
• Application Number:
  US14/814,335
• Publication Number:
  US 20160031743A1
• Time in Patent Office: 1,146 Days
• Field of Search: 428141, 428220, 428410, 428426
• CPC Class Codes: B32B 17/10036 comprising two outer glass sheets
• CPC Class Codes: B60J 1/001 Double glazing for vehicles
• 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: C03B 27/016 by absorbing heat radiated from the glass product
• CPC Class Codes: C03B 27/04 using gas
• CPC Class Codes: C03B 27/0404 Nozzles, blow heads, blowing units or their arrangements, specially adapted for flat or bent glass sheets
• CPC Class Codes: C03B 27/0413 Stresses, e.g. patterns, values or formulae for flat or bent glass sheets
• CPC Class Codes: C03B 27/044 for flat or bent glass sheets being in a horizontal position
• CPC Class Codes: C03B 27/048 on a gas cushion
• CPC Class Codes: C03B 27/052 for flat or bent glass sheets being in a vertical position
• CPC Class Codes: C03B 27/0526 Stresses, e.g. patterns, values or formulae
• CPC Class Codes: C03B 29/12 being in a horizontal position on a fluid support, e.g. a gas or molten metal
• CPC Class Codes: C03B 29/16 Glass sheets
• CPC Class Codes: C03B 35/24 on a gas support bed
• CPC Class Codes: C03C 21/002 to perform ion-exchange between alkali ions C03C21/005 takes precedence
• CPC Class Codes: C03C 3/11 containing halogen or nitrogen
• CPC Class Codes: Y02P 40/57 Improving the yield, e-g- reduction of reject rates
• CPC Class Codes: Y10T 428/315 Surface modified glass [e.g., tempered, strengthened, etc.]

Abstract

A strengthened glass sheet product along with a process and an apparatus for strengthening a glass sheet are provided. 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.

Claims

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 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 glass sheet having a thermally induced central tension of less than 300 MPa and greater than

2. The glass sheet according to claim 1 wherein h_CT is greater than or equal to 0.022.

3. The glass sheet according to claim 1 wherein h_CT is greater than or equal to 0.024.

4. The glass sheet according to claim 1 wherein h_CT is greater than or equal to 0.026.

5. The glass sheet according to claim 1 wherein h_CT is greater than or equal to 0.028.

6. The glass sheet according to claim 1 wherein h_CT is greater than or equal to 0.030.

7. The glass sheet according to claim 1 wherein h_CT is greater than or equal to 0.0625.

8. The glass sheet according to claim 1 wherein h_CT is greater than or equal to 0.065.

9. The glass sheet according to claim 1 wherein the first surface of the sheet is flat to 50 μ

m total indicator run-out (TIR) along any 50 mm or less profile of the first major surface.

10. The glass sheet according to claim 1 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 μ

m×

10 μ

m.

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

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

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

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

15. The glass sheet according to claim 13, wherein the ratio l/t and the ratio w/t each are equal to 20/1 or more.

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

17. The glass sheet according to claim 1 wherein t is 6 mm or less.

18. The glass sheet according to claim 1 wherein t is 3 mm or less.

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

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

21. The glass sheet according to claim 15 wherein t is 0.7 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 t is 0.28 mm or less.

24. 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.

25. The glass sheet according to claim 21 wherein the sheet exhibits a 50% cracking threshold at 10 Newtons or greater after a 15 second Vickers Hardness Test.

26. A thermally strengthened glass sheet according to claim 1 wherein first major surface of the glass sheet having a thermally induced surface compressive stress of less than 600 MPa and greater than

27. The sheet according to claim 26 wherein h is greater than or equal to 0.026.

28. The glass sheet according to claim 1 wherein the glass has 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 θ

s given by (Tfs−

T_anneal)/(T_soft−

T_anneal),

wherein the parameter θ

s is in the range of from 0.20 to 0.9.

29. The glass sheet according to claim 28 wherein the parameter θ

s is in the range of from 0.50 to 0.9.

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

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

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

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

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

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

36. The glass sheet according to claim 1, 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.

37. The glass sheet according to claim 1, 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.