Damage resistant glass with high coefficient of thermal expansion

Patent metadata

Field	Value
Publication number	US-9969644-B2
Application number	US-201414465888-A
Country	US
Kind code	B2
Filing date	Aug 22, 2014
Priority date	Aug 27, 2013
Publication date	May 15, 2018
Grant date	May 15, 2018

Abstract

Ion exchangeable glasses having coefficients of thermal expansion (CTE) at least about 90×10 −7 ° C. −1 . The glasses undergo rapid ion exchange, for example, in a molten KNO 3 salt bath to a depth of layer of greater than 30 microns in less than 2 hours at temperatures of 370° C. to 390° C. When ion-exchanged to a depth of layer between 30 to 50 microns, the glasses exhibit a Vickers median/radial crack initiation threshold exceeding 30 kilograms force (kgf). The glasses are fusion formable and, in some embodiments, compatible with zircon.

First claim

The invention claimed is:

1. A glass, the glass comprising SiO 2 , from 6 mol % to 17 mol % Al 2 O 3 , greater than 5 mol % P 2 O 5 , and greater than 1 mol % K 2 O, wherein
R 2 O+R′O is greater than 18 mol %, where R is at least one alkali metal and R′ is at least one alkaline earth oxide,
the glass is substantially free of B 2 O 3 , and
the glass has a coefficient of thermal expansion of greater than 95×10 −7 ° C. −1 .

2. The glass of claim 1 , wherein the glass is ion exchanged and has a Vickers crack initiation threshold in a range from greater than 20 kgf to 50 kgf.

3. The glass of claim 2 , wherein the Vickers crack initiation threshold is in a range from 30 kgf up to 50 kgf.

4. The glass of claim 2 , wherein the glass has a compressive layer extending from a surface of the glass to a depth of layer of at least 30 μm.

5. The glass of claim 4 , wherein the depth of layer is in a range from 30 μm up to 50 μm.

6. The glass of claim 4 , wherein the compressive layer has a compressive stress of at least 800 MPa.

7. The glass of claim 4 , wherein the glass has been ion exchanged in an ion exchange bath comprising KNO 3 at a temperature in a range from 370° C. to 390° C. for up to two hours.

8. The glass of claim 1 , wherein the glass has a liquidus temperature T L , a 160 kP temperature T 160kP , a 35 kP temperature T 35kP , and a zircon breakdown temperature T breakdown , wherein T L <T 160kP and T breakdown >T 35kP .

9. The glass of claim 1 , wherein the glass comprises from 57 mol % to 75 mol % SiO 2 ; from 6 mol % to 17 mol % Al 2 O 3 ; from greater than 5 mol % to 7 mol % P 2 O 5 ; from 14 mol % to 17 mol % Na 2 O; and from greater than 1 mol % to 5 mol % K 2 O.

10. The glass of claim 9 , comprising from 0 mol % to 2 mol % MgO.

11. The glass of claim 9 , wherein the glass comprises from 57 mol % to 59 mol % SiO 2 ; from greater than 13 mol % to 17 mol % Al 2 O 3 ; from greater than 5 mol % to 7 mol % P 2 O 5 ; from 16 mol % to 17 mol % Na 2 O; and from 1 mol % to 5 mol % K 2 O.

12. The glass of claim 1 , wherein the glass comprises at least 13 mol % Al 2 O 3 .

13. The glass of claim 1 , wherein the glass is substantially free of MgO.

14. The glass of claim 1 , wherein the glass, when ion exchanged for one hour at 390° C. in a KNO 3 bath, has a Vickers crack initiation threshold of greater than 20 kgf.

15. An appliance, comprising the glass of claim 1 .

16. The appliance of claim 15 , further comprising a display.

17. An ion exchanged glass, the ion exchanged glass comprising SiO 2 , from 6 mol % to 17 mol % Al 2 O 3 , greater than 5 mol % P 2 O 5 , greater than 1 mol % K 2 O, wherein R 2 O+R′O is greater than 18 mol %, where R is at least one alkali metal and R′ is at least one alkaline earth oxide, and the glass is substantially free of B 2 O 3 , and wherein the glass has a coefficient of thermal expansion of greater than 95×10 −7 ° C. −1 and has a Vickers crack initiation threshold in a range from greater than 20 kgf to 50 kgf.

18. The ion exchanged glass of claim 17 , wherein the Vickers crack initiation threshold is in a range from 30 kgf up to 50 kgf.

19. The ion exchanged glass of claim 17 , wherein the glass has a compressive layer extending from a surface of the glass to a depth of layer of at least 30 μm.

20. The ion exchanged glass of claim 19 , wherein the depth of layer is in a range from 30 μm up to 50 μm.

21. The ion exchanged glass of claim 19 , wherein the compressive layer has a compressive stress of at least 800 MPa.

22. The ion exchanged glass of claim 19 , wherein the ion exchanged glass has been ion exchanged in an ion exchange bath comprising KNO 3 at a temperature in a range from 370° C. to 390° C. for up to two hours.

23. The ion exchanged glass of claim 17 , wherein the ion exchanged glass has a liquidus temperature T L , a 160 kP temperature T 160kP , a 35 kP temperature T 35kP , and a zircon breakdown temperature T breakdown , wherein T L <T 160P and T breakdown >T 35kP .

24. The ion exchanged glass of claim 17 , wherein the ion exchanged glass comprises from 57 mol % to 59 mol % SiO 2 ; from greater than 13 mol % to 17 mol % Al 2 O 3 ; from greater than 5 mol % to 7 mol % P 2 O 5 ; from 16 mol % to 17 mol % Na 2 O; and from greater than 1 mol % to 5 mol % K 2 O.

25. The ion exchanged glass of claim 24 , further comprising up to 2 mol % MgO.

26. The ion exchanged glass of claim 17 , wherein the ion exchanged glass comprises at least 13 mol % Al 2 O 3 .

27. The ion exchanged glass of claim 17 , wherein the ion exchanged glass is substantially free of MgO.

28. An appliance, comprising the ion exchanged glass of claim 17 .

29. The appliance of claim 28 , further comprising a display.

30. A method of ion exchanging a glass, the method comprising:
a. providing a glass, the glass comprising SiO 2 , from 6 mol % to 17 mol % Al 2 O 3 , greater than 5 mol % P 2 O 5 , and greater than 1% K 2 O, wherein R 2 O+R′O is greater than 18 mol %, where R is at least one alkali metal and R′ is at least one alkaline earth oxide, the glass being substantially free of B 2 O 3 and having a coefficient of thermal expansion of greater than 95×10 −7 ° C. −1 ;
b. providing an ion exchange bath, wherein the ion exchange bath comprises KNO 3 and is at a temperature in a range from 370° C. to 390° C.; and
c. ion exchanging the glass in the ion exchange bath for a time period of up to two hours, wherein the ion exchanged glass has a layer under a compressive stress, the layer extending from a surface of the glass to a depth of layer of at least 30 μm.

31. The method of claim 30 , wherein the ion exchanged glass has a Vickers crack initiation threshold of at least 4-5 in a range from 20 kgf to 50 kgf.

32. The method of claim 31 , wherein the Vickers crack initiation threshold is in a range from 30 kgf up to 50 kgf.

33. The method of claim 30 , wherein the depth of layer is in a range from 30 μm up to 50 μm.

34. The method of claim 30 , wherein the compressive stress is at least 800 MPa.

35. The method of claim 30 , wherein the ion exchanged glass comprises from 57 mol % to 59 mol % SiO 2 ; from greater than 13 mol % to 17 mol % Al 2 O 3 ; greater than 5 mol % to 7 mol % P 2 O 5 ; from 16 mol % to 17 mol % Na 2 O; and greater than 1 mol % to 5 mol % K 2 O.

36. The method of claim 35 , further comprising up to 2 mol % MgO.

37. The method of claim 30 , wherein the ion exchanged glass comprises at least 13 mol % Al 2 O 3 .

Assignees

• Corning Inc

Inventors

• Gross Timothy Michael
• Guo Xiaoju

Classifications

• C03C2204/00

  Glasses, glazes or enamels with special properties · CPC title

• C03C3/097 Primary

  containing phosphorus, niobium or tantalum · CPC title

• C03C21/002

  to perform ion-exchange between alkali ions (C03C21/005 takes precedence) · CPC title

• C03C4/18

  for ion-sensitive glass · CPC title

• Y10T428/315

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