Strengthened glass with deep depth of compression

Patent metadata

Field	Value
Publication number	US-9487434-B2
Application number	US-201615158167-A
Country	US
Kind code	B2
Filing date	May 18, 2016
Priority date	Feb 24, 2014
Publication date	Nov 8, 2016
Grant date	Nov 8, 2016

Abstract

Chemically strengthened glass articles having at least one deep compressive layer extending from a surface of the article to a depth of at least about 45 μm within the article are provided. In one embodiment, the compressive stress profile includes a single linear segment extending from the surface to the depth of compression DOC. Alternatively, the compressive stress profile includes two linear portions: the first portion extending from the surface to a relatively shallow depth and having a steep slope; and a second portion extending from the shallow depth to the depth of compression. The strengthened glass has a 60% survival rate when dropped from a height of 80 cm in an inverted ball drop test and an equibiaxial flexural strength of at least 10 kgf as determined by abraded ring-on-ring testing. Methods of achieving such stress profiles are also described.

First claim

The invention claimed is:

1. A glass article having a thickness t, the glass article comprising:
a compressive layer having a compressive stress CS in a range from about 500 MPa up to about 1200 MPa at a surface of the glass article, wherein:
a. the compressive layer extends from the surface to a depth of compression DOC, wherein DOC≧0.1·t when t<0.5 mm and DOC≧50 μm when t≧0.5 mm, and wherein the compressive layer has a compressive stress profile; and
b. the compressive stress profile comprises:
i. a first portion b extending from the surface to a depth d b and having an average slope m b , wherein 3 μm≦d b ≦15 μm and −40 MPa/μm≧m b ≧−200 MPa/μm;
ii. a second portion c extending from a depth d c to the DOC and having an average slope m c , wherein −2 MPa/μm≧m c ≧−8 MPa/μm; and
iii. a transition region extending from d b to d c having a slope that transitions from slope m b to slope m c .

2. The glass article of claim 1 , wherein −40 MPa/μm≧m b ≧−120 MPa/μm.

3. The glass article of claim 1 , wherein thickness t is in a range from about 0.15 mm up to about 2.0 mm.

4. The glass article of claim 1 , wherein the glass article comprises an alkali aluminosilicate glass.

5. The glass article of claim 4 , wherein the alkali aluminosilicate glass further comprises up to about 10 mol % Li 2 O.

6. The glass article of claim 1 , wherein the glass is lithium-free.

7. A glass article having a thickness t, the glass article comprising:
a compressive layer having a compressive stress CS in a range from about 500 MPa up to about 1200 MPa at a surface of the glass article, wherein:
a. the compressive layer extends from the surface to a depth of compression DOC, wherein DOC≧0.1·t when t<0.5 mm and DOC≧50 μm when t≧0.5 mm, and wherein the compressive layer has a compressive stress profile; and
b. the compressive stress profile comprises:
i. a first portion b extending from the surface to a depth d b and having a an average slope m b , wherein 3 μm≦d b ≦15 μm and −40 MPa/μm≧m b ≧−200 MPa/μm
ii. a second portion c extending from a depth d c to the DOC and having an average slope m c , and
iii. a transition region extending from d b to d c having a slope that transitions from slope m b to slope m c .

8. The glass article of claim 7 , wherein −40 MPa/μm≧m b ≧−120 MPa/μm.

9. The glass article of claim 7 , wherein thickness t is in a range from about 0.15 mm up to about 2.0 mm.

10. The glass article of claim 7 , wherein the glass article comprises an alkali aluminosilicate glass.

11. The glass article of claim 10 , wherein the alkali aluminosilicate glass further comprises up to about 10 mol % Li 2 O.

12. The glass article of claim 7 , wherein the glass is lithium-free.

13. The glass article of claim 7 , wherein the first portion b is linear such that



σ
″

⁡

(
x
)



<



2
⁢

σ
′

⁡

(
x
)

d
b



where σ″(x) is the second derivative of the stress profile in the first portion b with respect to depth x and σ′(x) is the first derivative of the stress profile in the first portion b with respect to depth x.

14. The glass article of claim 13 , wherein the first portion b is linear such that



σ
″

⁡

(
x
)



<



σ
′

⁡

(
x
)

d
b



.

15. A glass article having a thickness t, the glass article comprising:
a compressive layer having a compressive stress CS in a range from about 500 MPa up to about 1200 MPa at a surface of the glass article, wherein:
a. the compressive layer extends from the surface to a depth of compression DOC, wherein DOC≧0.1·t when t<0.5 mm and DOC≧50 μm when t≧0.5 mm, and wherein the compressive layer has a compressive stress profile; and
b. the compressive stress profile comprises:
i. a first portion b extending from the surface to a depth d b and having an average slope m b , wherein 3 μm≦d b ≦15 μm;
ii. a second portion c extending from a depth d c to the DOC and having an average slope m c , wherein −2 MPa/μm≧m c ≧−8 MPa/μm; and
iii. a transition region extending from d b to d c having a slope that transitions from slope m b to slope m c .

16. The glass article of claim 15 , wherein thickness t is in a range from about 0.15 mm up to about 2.0 mm.

17. The glass article of claim 15 , wherein the glass article comprises an alkali aluminosilicate glass.

18. The glass article of claim 17 , wherein the alkali aluminosilicate glass further comprises up to about 10 mol % Li 2 O.

19. The glass article of claim 15 , wherein the glass is lithium-free.

20. The glass article of claim 15 , wherein the second portion c is linear such that



σ
″

⁡

(
x
)



<



2
⁢

σ
′

⁡

(
x
)

d
c



where σ″(x) is the second derivati

Assignees

• Corning Inc

Inventors

• Amin Jaymin
• Egboiyi Benedict Osobomen
• Pesansky Jonathan David
• Reiman Kevin Barry
• Roussev Rostislav Vatchev
• Strines Brian Paul

Classifications

• C03C3/091

  containing aluminium · CPC title

• C03C3/093

  containing zinc or zirconium · CPC title

• G06F2200/1634

  Integrated protective display lid, e.g. for touch-sensitive display in handheld computer · CPC title

• C03C3/097 Primary

  containing phosphorus, niobium or tantalum · CPC title

• C03C3/087

  containing calcium oxide, e.g. common sheet or container glass · CPC title