# US 11,079,309 B2 · Strengthened glass articles having improved survivability

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- Number: US 11,079,309 B2
- Document ID: US11079309B2
- Status: Granted
- Kind: B2
- Application number: 14/340,670
- Filed: 2014-07-25
- Published: 2015-01-29
- Granted: 2021-08-03
- Earliest claimed: 2013-07-26
- Assignees: Corning Incorporated
- Applicants: Corning Incorporated
- Inventors: Laurence Ralph Morey; Jonathan David Pesansky; Kevin Barry Reiman; Benjamin Allen Stevens; Brian Paul Strines
- Web page: https://patentgrep.com/patent/US11079309B2

## CPC

- G01N 3/30: by applying a single impulsive force, e.g. by falling weight
- C03C 3/091: containing aluminium
- C03C 3/093: containing zinc or zirconium
- C03C 3/097: containing phosphorus, niobium or tantalum
- C03C 21/002: {to perform ion-exchange between alkali ions (C03C21/005 takes precedence)}
- Y10T 428/315: Surface modified glass [e.g., tempered, strengthened, etc.]
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## 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 CSs (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 CSs/DOL ratio≥2.5 MPa/μm.

## Claims

### Claim 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 DOL is greater than or equal to 70 μm,
wherein the strengthened glass article is under a compressive stress at the surface CSs,
wherein the strengthened glass article is an alkali aluminosilicate glass article comprising 0 mol % Li2O, and at least 3 mol % Al2O3, and
wherein the strengthened glass article has a stress profile such that a compressive stress CSD at an intermediate critical depth of 50 μm below the surface of the strengthened glass article is at least 10% of CSs.

### Claim 2 (depends on 1)

The strengthened glass article of claim 1, wherein the CSs>300 MPa.

### Claim 3 (depends on 1)

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

### Claim 4 (depends on 1)

The strengthened glass article of claim 1, wherein the thickness t≤0.9 mm.

### Claim 5 (depends on 1)

The strengthened glass article of claim 1, wherein CSD is at least 50 MPa.

### Claim 6 (depends on 1)

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

### Claim 7 (depends on 1)

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

### Claim 8 (depends on 1)

The strengthened glass article of claim 1, wherein the CSs/DOL ratio is in a range from 8 MPa/μm to 10 MPa/μm.

### Claim 9 (depends on 1)

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

### Claim 10 (depends on 1)

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

### Claim 11 (depends on 1)

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

### Claim 12 (depends on 1)

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.

### Claim 13 (depends on 1)

The strengthened glass article of claim 1, wherein the CT is less than or equal to 150 MPa.

### Claim 14 (depends on 1)

The strengthened glass article of claim 1, wherein the CSs/DOL ratio is in a range from 3 MPa/μm to 12 MPa/μm.

### Claim 15 (depends on 14)

The strengthened glass article of claim 14, wherein the CSs/DOL ratio is in a range from 3 MPa/μm to 5 MPa/μm.

### Claim 16 (depends on 1)

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.

### Claim 17 (depends on 1)

The strengthened glass article of claim 1, wherein the CSs≥350 MPa.

### Claim 18 (depends on 1)

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 comprising 180 grip alumina sandpaper utilizing a uniform drop rate procedure, wherein the survival rate is based on testing at least 5 samples.

### Claim 19 (depends on 18)

The strengthened glass of claim 18, wherein the strengthened glass is incorporated into an electronic device.

### Claim 20 (depends on 1)

The strengthened glass article of claim 1, wherein CSs/DOL≥2.5 MPa/μm.

### Claim 21 (depends on 1)

A method of producing the strengthened glass article according to claim 1, 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 which is great than or equal 70 μm, 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 μm after the first ion exchange step; and
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 stress layer having DOL, wherein the strengthened glass article has a stress profile such that a compressive stress CSD at an intermediate critical depth of 50 μm below the surface of the strengthened glass article is at least 10% of a compressive stress at the surface CSs, and wherein the strengthened glass article comprises 0 mol % Li2O.

### Claim 22 (depends on 21)

The method of claim 21, wherein the first ion exchange step is conducted for a time of at least 8 hours.

### Claim 23 (depends on 21)

The method of claim 21, 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.

### Claim 24 (depends on 23)

The method of claim 23, wherein the first ion exchange bath comprises from about 30% to about 60% by weight of the sodium composition.

### Claim 25 (depends on 21)

The method of claim 21, wherein the temperature of the first ion exchange step is 435° C. or greater.

### Claim 26 (depends on 21)

The method of claim 21, wherein the strengthened glass article has a compressive stress of at least 150 MPa after the first ion exchange step.

### Claim 27 (depends on 26)

The method of claim 26, wherein the strengthened glass article has a compressive stress of about 200 to about 400 MPa after the first ion exchange step.

### Claim 28 (depends on 21)

The method of claim 21, wherein the second ion exchange step is conducted for a time of 75 minutes or less.

### Claim 29 (depends on 28)

The method of claim 28, wherein the second ion exchange step is conducted for a time of about 10 to about 20 minutes.

### Claim 30 (depends on 21)

The method of claim 21, 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.

### Claim 31 (depends on 30)

The method of claim 30, wherein the second ion exchange bath comprises from about 98% to about 99.5% by weight of the potassium composition.

### Claim 32 (depends on 30)

The method of claim 30, wherein the second ion exchange bath comprises 0-2% by weight of a sodium composition.

### Claim 33 (depends on 21)

The method of claim 21, wherein the temperature of the second ion exchange step is 360° C. or greater.

### Claim 34 (depends on 21)

The method of claim 21, wherein the strengthened glass article has a compressive stress of at least 700 MPa after the second ion exchange step.

### Claim 35 (depends on 34)

The method of claim 34, wherein the strengthened glass article has a compressive stress of 700 to about 1000 MPa after the second ion exchange step.

### Claim 36 (depends on 21)

The method of claim 21, wherein the compressive stress layer has a depth of 70 μm to 85 μm after the first ion exchange step.

### Claim 37 (depends on 21)

The method of claim 21, wherein the DOL is in a range from 70 μm to 100 μm after the second ion exchange step.

### Claim 38

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 DOL is greater than or equal to 70 μm,
wherein strengthened glass article is under a compressive stress at the surface CSs,
wherein the strengthened glass article is an alkali aluminosilicate glass article comprising 0mol % Li2O, at least 3 mol % Al2O3, and at least 5 mol % Na2O,
and
wherein the strengthened glass article has a stress profile such that a compressive stress CSD at an intermediate critical depth of 50 μm below the surface of the strengthened glass article is at least 10% of a compressive stress at the surface CSs, and the CT≤150 MPa.

### Claim 39 (depends on 38)

The strengthened glass article of claim 38, wherein the CSs>300 MPa.

### Claim 40 (depends on 38)

The strengthened glass article of claim 38, wherein the CSs/DOL ratio is in a range from 3 MPa/μm to 12 MPa/μm.

### Claim 41 (depends on 38)

The strengthened glass article of claim 38, wherein the CSs≥350 MPa.

### Claim 42 (depends on 38)

The strengthened glass article of claim 38, wherein the thickness t≤0.9 mm.

### Claim 43 (depends on 38)

The strengthened glass article of claim 38, wherein the DOL is in a range from 0.1t to 0.3t, where DOL is expressed in mm.

### Claim 44 (depends on 38)

The strengthened glass article of claim 38, 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 comprising 180 grit alumina sandpaper utilizing a uniform drop rate procedure, wherein the survival rate is based on testing at least 5 samples.

### Claim 45 (depends on 44)

The strengthened glass of claim 44, wherein the strengthened glass is incorporated into an electronic device.

### Claim 46 (depends on 45)

The strengthened glass article of claim 45, wherein CSD is at least 50 MPa.

### Claim 47

A strengthened glass, the strengthened glass comprising:
a thickness t≤1 mm,
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, p1 wherein the strengthened glass article has a stress profile such that a compressive stress CSD at an intermediate critical depth of 50 μm below the surface of the strengthened glass article is at least 10% of a compressive stress at the surface CSs,
wherein the strengthened glass comprises 0 mol % Li2O, and
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 comprising 180 grit alumina sandpaper utilizing a uniform drop rate procedure, wherein the survival rate is based on testing at least 5 samples.

### Claim 48 (depends on 47)

The strengthened glass of claim 47, wherein the strengthened glass is incorporated into an electronic device.

### Claim 49 (depends on 47)

The strengthened glass of claim 47, 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.

### Claim 50 (depends on 49)

The strengthened glass of claim 49, wherein the non-flat angle is 30° relative to the drop surface.