# US 12,006,248 B2 · White glass-ceramic substrates and articles including tetragonal zirconia crystalline phase, and method of manufacturing the same

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- Number: US 12,006,248 B2
- Document ID: US12006248B2
- Status: Granted
- Kind: B2
- Application number: 18/211,702
- Filed: 2023-06-20
- Published: 2023-11-02
- Granted: 2024-06-11
- Earliest claimed: 2020-06-30
- Assignees: Corning Incorporated
- Applicants: Corning Incorporated
- Inventors: Carol Ann Click; Qiang Fu; Mathieu Gerard Jacques Hubert; Charlene Marie Smith; Alana Marie Whittier
- Web page: https://patentgrep.com/patent/US12006248B2

## CPC

- C03C 3/097: containing phosphorus, niobium or tantalum
- C03C 10/0027: {containing SiO2, Al2O3, Li2O as main constituents}
- C03C 4/02: for coloured glass
- C03C 10/0036: {containing SiO2, Al2O3 and a divalent metal oxide as main constituents}
- C03C 10/0054: {containing PbO, SnO2, B2O3}
- C03C 21/002: {to perform ion-exchange between alkali ions (C03C21/005 takes precedence)}
- C03C 21/005: {to introduce in the glass such metals or metallic ions as Ag, Cu}
- C03C 2204/04: Opaque glass, glaze or enamel
- 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

## Abstract

A glass-ceramic article comprises: a center-volume composition comprising (on an oxide basis): 55-75 mol % SiO2; 0.2-10 mol % Al2O3; 0-5 mol % B2O3; 15-30 mol % Li2O; 0-2 mol % Na2O; 0-2 mol % K2O; 0-5 mol % MgO; 0-2 mol % ZnO; 0.2-3.0 mol % P2O5; 0.1-10 mol % ZrO2; 0-4 mol % TiO2; and 0-1.0 mol % SnO2. Lithium disilicate and either β-spodumene or β-quartz are the two predominant crystalline phases (by weight) of the glass-ceramic article. The glass-ceramic article further comprises tetragonal ZrO2 as a crystalline phase. The composition of the glass-ceramic article from a primary surface into a thickness of the glass-ceramic article can comprise over 10 mol % Na2O (on an oxide basis), with the mole percentage of Na2O decreasing from the primary surface towards the center-volume. The glass-ceramic article exhibits a ring-on-ring load-to-failure of at least 120 kgf, when the thickness of the glass-ceramic article is 0.3 mm to 2.0 mm.

## Claims

### Claim 1

A method of manufacturing a glass-ceramic article comprising:
(a) maintaining a precursor glass in an environment for a first time period of 1.75 to 4.25 hours while the environment has a first temperature of 590° C. to 820° C., the precursor glass having a composition comprising, on an oxide basis:
55-75 mol % SiO2;
0.2-10 mol % Al2O3;
0-5 mol % B2O3;
15-30 mol % Li2O;
0-2 mol % Na2O;
0-2 mol % K2O;
0-5 mol % MgO;
0-2 mol % ZnO;
0.2-3.0 mol % P2O5;
0.1-10 mol % ZrO2;
0-4 mol % TiO2; and
0-1.0 mol % SnO2;
(b) maintaining the precursor glass in the environment for a second time period of 0.75 hour to 4.25 hours while the environment has a second temperature of 850° C. to 925° C., forming a glass-ceramic substrate, wherein (i) lithium disilicate and (ii) either β-spodumene or β-quartz are the two predominant crystalline phases by weight percentage of the glass-ceramic substrate, and wherein tetragonal ZrO2 is a crystalline phase of the glass-ceramic substrate; and
(c) subjecting the glass-ceramic substrate to an ion-exchange treatment in a molten salt bath that comprises a salt of one or more of ionic Na, K, and Ag, forming a glass-ceramic article.

### Claim 2 (depends on 1)

The method of claim 1, wherein:
the precursor glass was characterized by Na2O+K2O≤0.5 mol %, but sodium ions are present throughout the entire thickness of the glass-ceramic article.

### Claim 3 (depends on 1)

The method of claim 1, wherein:
the composition of a portion of the glass-ceramic article from the primary surface into the thickness comprises over 10 mol % Na2O, on an oxide basis.

### Claim 4 (depends on 1)

The method of claim 1, wherein:
the bath of the ion-exchange treatment comprises greater than 98 percent by weight NaNO3 and 0.01 to 1 percent by weight LiNO3; and the mole percentage of Na2O within the glass-ceramic article decreases as a function of depth into the thickness of the glass-ceramic article from the primary surface, with the maximum mole percentage of Na2O at any depth being 7 mol % Na2O, and sodium ions are present within the glass-ceramic article to a depth of at least 15 percent of the thickness from the primary surface.

### Claim 5 (depends on 1)

The method of claim 1, wherein:
the ion-exchange treatment comprises the first ion-exchange treatment in which the first bath comprises at least 98 percent by weight NaNO3 and the second ion-exchange step in which the second bath comprises ions of potassium or silver; and (i) the first portion of the thickness of the glass-ceramic article comprises a mole percentage of either K2O or Ag2O that is greater than the mole percentage of Na2O and (ii) the second portion of the thickness of the glass-ceramic article comprises a mole percentage of Na2O that is greater than the mole percentage of either K2O or Ag2O.

### Claim 6 (depends on 1)

The method of claim 1, wherein:
the precursor glass was substantially free of Na2O.

### Claim 7 (depends on 1)

The method of claim 1, wherein:
the first temperature is in the range of 590° C. to 770° C.

### Claim 8 (depends on 1)

The method of claim 1, wherein:
the glass-ceramic substrate has a fracture toughness of 1.0 to 3.0 MPa·m1/2.

### Claim 9 (depends on 1)

The method of claim 1, wherein:
the thickness of the glass-ceramic article is 0.3 mm to 2.0 mm.

### Claim 10 (depends on 9)

The method of claim 9, wherein:
the glass-ceramic article exhibits a ring-on-ring load-to-failure of at least 120 kgf.

### Claim 11 (depends on 9)

The method of claim 9, wherein:
after being abraded with SiC particles at an abrasion pressure of 45 psi, the glass-ceramic article exhibits a ring-on-ring load-to-failure of at least 80 kgf.

### Claim 12 (depends on 1)

The method of claim 1, wherein:
the glass-ceramic substrate exhibits a color, under an F02 illuminant, presented in CIELAB color space coordinates:
L*=88 to 98;
a*=−1.0 to 1; and
b*=−4.0 to 4.0.

### Claim 13 (depends on 1)

The method of claim 1, wherein:
the composition of the precursor glass comprises, on an oxide basis:
68.6-71.5 mol % SiO2;
1.0-4.5 mol % Al2O3;
21.5-22.2 mol % Li2O;
0.7-1.2 mol % P2O5;
1.5-5.0 mol % ZrO2; and
0-1.0 mol % SnO2, wherein the precursor glass is substantially free of B2O3; Na2O; K2O; MgO; ZnO; and TiO2.

### Claim 14 (depends on 1)

The method of claim 1, wherein:
the composition of the precursor glass comprises, on an oxide basis:
68.6-70.9 mol % SiO2;
1.0-4.3 mol % Al2O3;
21.5-22.2 mol % Li2O;
0.9-1.2 mol % P2O5;
2.0-5.0 mol % ZrO2; and
0-1.0 mol % SnO2, wherein the precursor glass is substantially free of B2O3; Na2O; K2O; MgO; ZnO; and TiO2.

### Claim 15 (depends on 1)

The method of claim 1, wherein:
the glass-ceramic substrate has a fracture toughness of 1.4 to 2.4 MPa·m1/2.

### Claim 16 (depends on 1)

The method of claim 1, wherein:
the glass-ceramic substrate exhibits a color, under an F02 illuminant, presented in CIELAB color space coordinates:
L*=93 to 97;
a*=−1.0 to 0; and
b*=−1.0 to 3.0.

### Claim 17 (depends on 1)

The method of claim 1, wherein:
the glass-ceramic substrate has an average opacity of 79 to 96 percent throughout the wavelength range of 400 nm to 700 nm for a thickness of 0.8 mm.

### Claim 18 (depends on 1)

The method of claim 1, wherein:
the precursor glass comprises 3.4 mol % to 4.3 mol % Al2O3; and
lithium disilicate and β-spodumene are the two predominant crystalline phases by weight of the glass-ceramic article.

### Claim 19 (depends on 1)

The method of claim 1, wherein:
the precursor glass comprises, on an oxide basis:
70.0-70.6 mol % SiO2;
4.85-4.95 mol % Al2O3;
19.2-19.4 mol % Li2O;
0.195-0.205 mol % Na2O;
0.9-1.1 mol % P2O5;
1.8-2.6 mol % ZrO2;
1.9-2.1 mol % TiO2; and
0.09-0.11 mol % SnO2, wherein the precursor glass is substantially free of B2O3; K2O; MgO; and ZnO; and
β-spodumene and lithium disilicate are the two predominant crystalline phases by weight of the glass-ceramic article.

### Claim 20 (depends on 19)

The method of claim 19, wherein:
the glass-ceramic article further comprises rutile as a crystalline phase.