STRENGTHENED GLASS ARTICLES HAVING IMPROVED SURVIVABILITY

• US 20150030834A1
• Filed: 07/25/2014
• Published: 01/29/2015
• Est. Priority Date: 07/26/2013
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Pesansky, Jonathan David, Reiman, Kevin Barry, Stevens, Benjamin Allen, Morey, Laurence Ralph, Strines, Brina Paul
• Granted Patent: US 11,079,309 B2
• Time in Patent Office: Days
• US Class Current: 428/220
• CPC Class Codes: C03C 21/002 to perform ion-exchange between alkali ions C03C21/005 takes precedence
• CPC Class Codes: C03C 3/091 containing aluminium
• CPC Class Codes: C03C 3/093 containing zinc or zirconium
• CPC Class Codes: C03C 3/097 containing phosphorus, niobium or tantalum
• CPC Class Codes: G01N 3/30 by applying a single impulsive force, e.g. by falling weight
• CPC Class Codes: Y10T 428/315 Surface modified glass [e.g., tempered, strengthened, etc.]

Abstract

Embodiments are directed to strengthened glass articles comprising a thickness t≦1 mm (1000 μm), an inner region under a central tension CT (in MPa), and at least one compressive stress layer adjacent the inner region and extending within the strengthened glass article from a surface of the strengthened glass article to a depth of layer DOL (in μm), wherein the strengthened glass article is under a compressive stress at the surface CS_s (in MPa), wherein the strengthened glass article is an alkali aluminosilicate glass article comprising 0-5 mol % Li₂O, and at least 3 mol % Al₂O₃, and wherein the DOL≧70 μm, and a CS_s/DOL ratio≧2.5 MPa/μm.

Claims

1. A strengthened glass article comprising:

a thickness t≦

1 mm, an inner region under a central tension CT, and at least one compressive stress layer adjacent the inner region and extending within the strengthened glass article from a surface of the strengthened glass article to a depth of layer DOL, wherein the strengthened glass article is under a compressive stress at the surface CS_s,

wherein the strengthened glass article is an alkali aluminosilicate glass article comprising 0-5 mol % Li₂O, and at least 3 mol % Al₂O₃, and

wherein the DOL≧

70 μ

m, and a CS_s/DOL ratio≧

2.5 MPa/μ

m.

2. The strengthened glass article of claim 1, wherein the CS_s>

300 MPa.

3. The strengthened glass article of claim 1, wherein the strengthened glass article comprises 0-5 mol % K₂O.

4. The strengthened glass article of claim 1, wherein the thickness t≦

0.9 mm.

5. The strengthened glass article of claim 1, wherein the strengthened glass article has a stress profile such that a compressive stress CS_D at an intermediate critical depth of 50 μ

m below the surface of the strengthened glass article is at least 10% of CS_s,

6. The strengthened glass article of claim 5, wherein CS_D is at least 50 MPa.

7. The strengthened glass article of claim 1, wherein the strengthened glass article comprises from 5 mol % to 20 mol % Na₂O.

8. The strengthened glass article of claim 1, wherein the strengthened glass article comprises from 0 mol % to 10 mol % MgO.

9. The strengthened glass article of claim 1, wherein the CS_s/DOL ratio is in a range from 8 MPa/μ

m to 10 MPa/μ

m.

10. The strengthened glass article of claim 1, wherein the DOL is in a range from 0.2t to 0.1t.

11. The strengthened glass article of claim 1, wherein the DOL is in a range from 70 to 120 μ

m.

12. The strengthened glass article of claim 1, wherein the CS_s is in a range from 700 to 1200 MPa.

13. The strengthened glass article of claim 1, wherein the thickness t is in a range from about 0.4 mm to about 0.8 mm.

14. The strengthened glass article of claim 1, wherein the CT≧

150 MPa.

15. The strengthened glass article of claim 1, wherein the CS_s/DOL ratio is in a range from 3 MPa/μ

m to 12 MPa/μ

m.

16. The strengthened glass article of claim 15, wherein the CS_s/DOL ratio is in a range from 3 MPa/μ

m to 5 MPa/μ

m.

17. The strengthened glass article of claim 1, wherein the strengthened glass article has a stress profile defined by a first compressive stress zone which extends from the surface of the strengthened glass article to a distance x below the surface, and a second compressive stress zone extending from the distance x to the DOL, and

wherein the first compressive stress zone defines a rate r₁ of decrease of compressive stress from the surface to the distance x below the surface, the second compressive stress zone defines a rate r₂ of decrease of compressive stress from the distance x to the DOL, and wherein r₁≧

2r₂.

18. The strengthened glass article of claim 1, wherein the CS_s≧

350 MPa.

19. The strengthened glass article of claim 1, wherein the strengthened glass has at least a 60% survival rate when dropped in a drop test from a height of at least 100 cm onto a drop surface utilizing a uniform drop rate procedure.

20. The strengthened glass of claim 19, wherein the strengthened glass is incorporated into an electronic device.

21. A strengthened glass article comprising:

a thickness t≦

1 mm, an inner region under a central tension CT, and at least one compressive stress layer adjacent the inner region and extending within the strengthened glass article from a surface of the strengthened glass article to a depth of layer DOL, wherein the strengthened glass article is under a compressive stress at the surface CS_s,

wherein the strengthened glass article is an alkali aluminosilicate glass article comprising 0-5 mol % Li₂O, at least 3 mol % Al₂O₃, and at least 5 mol % Na₂O, and

wherein the DOL≧

70 μ

m, a CS_s/DOL ratio 2.5 MPa/μ

m, and wherein the strengthened glass article, when subjected to a point impact sufficient to break the strengthened glass article, has a frangibility index of less than 3.

22. The strengthened glass article of claim 21, wherein the CS_s>

300 MPa.

23. The strengthened glass article of claim 21, wherein the CS_s/DOL ratio is in a range from 3 MPa/μ

m to 12 MPa/μ

m.

24. The strengthened glass article of claim 21, wherein the CS_s≧

350 MPa.

25. The strengthened glass article of claim 21, wherein the thickness t≦

0.9 mm.

26. The strengthened glass article of claim 21, wherein the thickness t is in a range from about 0.4 mm to about 0.8 mm.

27. The strengthened glass article of claim 21, wherein the DOL is in a range from 0.2t to 0.1t, where DOL is expressed in millimeters.

28. A strengthened glass article comprising:

a thickness t≦

1 mm, an inner region under a central tension CT, and at least one compressive stress layer adjacent the inner region and extending within the strengthened glass article from a surface of the strengthened glass article to a depth of layer DOL, wherein the strengthened glass article is under a compressive stress at the surface CS_s,

wherein the strengthened glass article is an alkali aluminosilicate glass article comprising 0-5 mol % Li₂O, at least 3 mol % Al₂O₃, and at least 5 mol % Na₂O, and

wherein the DOL≧

70 μ

m, a CS_s/DOL ratio≧

3.0 MPa/μ

m, and the CT≦

150 MPa.

29. The strengthened glass article of claim 28, wherein the CS_s>

300 MPa.

30. The strengthened glass article of claim 28, wherein the CS_s/DOL ratio is in a range from 3 MPa/μ

m to 12 MPa/μ

m.

31. The strengthened glass article of claim 28, wherein the CS_s≧

350 MPa.

32. The strengthened glass article of claim 28, wherein the thickness t≦

0.9 mm.

33. The strengthened glass article of claim 28, wherein the DOL is in a range from 0.3 to 0.1t, where DOL is expressed in mm.

34. The strengthened glass article of claim 28, wherein the strengthened glass has at least a 60% survival rate when dropped in a drop test from a height of at least 100 cm onto a drop surface in a uniform test procedure.

35. The strengthened glass of claim 34, wherein the strengthened glass is incorporated into an electronic device.

36. The strengthened glass article of claim 28, wherein the strengthened glass article has a stress profile such that a compressive stress CS_D at an intermediate critical depth of 50 μ

m below the surface of the strengthened glass article is at least 10% of CS_s,

37. The strengthened glass article of claim 35, wherein CS_D is at least 50 MPa.

38. A strengthened glass, the strengthened glass having an inner region under a central tension CT, and at least one compressive stress layer under a compressive stress CS, the compressive stress layer extending from a surface of the glass to a depth of compression and being adjacent to the inner region, wherein the strengthened glass has at least a 60% survival rate when dropped in a drop test from a height of at least 100 cm onto a drop surface utilizing a uniform drop testing procedure.

39. The strengthened glass of claim 38, wherein the strengthened glass is incorporated into an electronic device.

40. The strengthened glass of claim 38, wherein the strengthened glass a 60% probability of withstanding fracture when the strengthened glass contacts the drop surface at a flat angle, at a non-flat angle, or both.

41. The strengthened glass of claim 38, wherein the non-flat angle is 30°

relative to the drop surface.

42. The strengthened glass of claim 38, wherein the drop surface is an abrasive sandpaper having a grit value in a range from about 150 to about 200 and an average grit particle size in a range from about 70 μ

m to about 90 μ

m.

43. A method of producing a strengthened glass article having a thickness t≦

1 mm and at least one compressive stress layer extending from a surface of the strengthened glass article to a depth of layer DOL≧

70 μ

m, the method comprising;

conducting a first ion exchange step by immersing an alkali aluminosilicate glass article in a first ion exchange bath at a temperature of greater than 400°

C. for a time sufficient such that the compressive stress layer has a depth of at least 70 μ

m after the first ion exchange step; and

optionally conducting a second ion exchange step by immersing the alkali aluminosilicate glass article in a second ion exchange bath different from the first ion exchange bath at a temperature of at least 350°

C. for a time sufficient to produce the compressive layer having DOL≧

90 μ

m.

44. The method of claim 43, wherein the first ion exchange step is conducted for a time of at least 8 hours.

45. The method of claim 43, wherein the first ion exchange bath comprises at least about 30% by weight of a sodium composition that delivers sodium ions to the alkali aluminosilicate glass article.

46. The method of claim 45, wherein the first ion exchange bath comprises from about 30% to about 60% by weight of the sodium composition.

47. The method of claim 43, wherein the temperature of the first ion exchange step is 435°

C. or greater.

48. The method of claim 43, wherein the strengthened glass article has a compressive stress of at least 150 MPa after the first ion exchange step.

49. The method of claim 48, wherein the strengthened glass article has a CS of about 200 to about 400 MPa after the first ion exchange step.

50. The method of claim 43, wherein the second ion exchange step is conducted for a time of 75 minutes or less.

51. The method of claim 50, wherein the second ion exchange step is conducted for a time of about 10 to about 20 minutes.

52. The method of claim 43, wherein the second ion exchange bath comprises at least about 95% by weight of a potassium composition that delivers potassium ions to the alkali aluminosilicate glass article.

53. The method of claim 52, wherein the second ion exchange bath comprises from about 98% to about 99.5% by weight of the potassium composition.

54. The method of claim 52, wherein the second ion exchange bath comprises 0-2% by weight of a sodium composition.

55. The method of claim 43, wherein the temperature of the second ion exchange step is 360°

C. or greater.

56. The method of claim 43, wherein the strengthened glass article has a compressive stress of at least 700 MPa after the second ion exchange step.

57. The method of claim 56, wherein the strengthened glass article has a compressive stress of about 700 to about 1000 MPa after the second ion exchange step.

58. The method of claim 43, wherein the compressive stress layer has a depth of 70 μ

m to 85 μ

m after the first ion exchange step.

59. The method of claim 43, wherein the DOL is in a range from 70 μ

m to 100 μ

m after the second ion exchange step.

60. A method of performing a glass drop test on a glass product, the method comprising:

providing a drop surface having an abrasive sandpaper upper surface, the abrasive sandpaper upper surface having a grit of at least 150;

dropping the glass product number of times (n) from a drop height, d_n=d₁+(n−

1)*k, onto the drop surface, wherein d₁ is an initial drop height, n refers to the number of repetitions of the glass drop within the glass drop test, and k is an increment for increasing drop heights for successive glass drop repetitions, and wherein the drop surface has an abrasive sandpaper upper surface, the abrasive sandpaper upper surface having a grit of at least 150;

determining if there is fracture in the strengthened glass product after each drop; and

ending the glass drop test upon detecting a fracture in the glass product or when the glass product is not fractured when dropped from a maximum drop height.

61. The method of claim 60, wherein dropping the glass product from the drop height onto the drop surface comprises dropping the glass product onto the drop surface such that the glass product contacts the drop surface at a flat angle relative to the drop surface.

62. The method of claim 61, wherein dropping the glass product from the drop height onto the drop surface comprises dropping the glass product onto the drop surface such that the glass product contacts the drop surface at a non-flat angle relative to the drop surface.

63. The method of claim 62, wherein the non-flat angle is 30°

.

64. The method of claim 60, wherein the drop surface is an abrasive sandpaper having a grit value in a range from about 150 to about 200 and an average grit particle size in a range from about 70 μ

m to about 90 μ

m.