阅读说明：本技术 具有改进的应力分布的玻璃陶瓷制品 (Glass-ceramic article with improved stress distribution ) 是由 D·L·J·达菲 C·L·菲埃诺 J·M·霍尔 金宇辉 V·M·施奈德 于 2019-08-14 设计创作，主要内容包括：通过离子交换过程制造了玻璃陶瓷制品,导致基于玻璃的制品具有改进的应力分布。拐点可位于3微米或更深的深度处。在表面处的压缩应力可以是200MPa或更大,在拐点处可以是20MPa或更大。非钠氧化物可以具有从第一表面到一定深度变化的非零浓度,压缩深度(DOC)可以位于0.10t或者甚至0.17t或更深的地方。例如二步骤离子交换(DIOX)包括：第一处理中的钾浴从而形成应力分布的尖峰区域中的尖峰；之后是第二处理,其包括例如钾钠混合浴,从而维持尖峰并形成应力分布的尾部区域。因此,玻璃陶瓷制品可以避免建立起玻璃质表面层,这有助于波导模式的可重现且可靠的测量,以及表面中的压缩应力(CS)和尖峰深度的确定。(Glass-ceramic articles are produced by ion exchange processes resulting in glass-based articles having improved stress profiles. The inflection point may be located at a depth of 3 microns or more. The compressive stress at the surface may be 200MPa or more and at the inflection point may be 20MPa or more. The non-sodium oxide may have a non-zero concentration that varies from the first surface to a depth, and the depth of compression (DOC) may be at 0.10t or even 0.17t or more. For example, two-step ion exchange (DIOX) includes: a potassium bath in the first treatment thereby forming a spike in the spike region of the stress distribution; this is followed by a second treatment comprising, for example, a potassium-sodium mixed bath, in order to maintain the spikes and form a tail region of the stress distribution. Thus, the glass-ceramic article may avoid the establishment of a glassy surface layer, which facilitates reproducible and reliable measurement of the waveguide mode, and determination of the Compressive Stress (CS) and the spike depth in the surface.)

1. A glass-ceramic article, comprising:

a glass-ceramic substrate having opposing first and second surfaces defining a substrate thickness (t);

a core composition at the center of the glass-ceramic article comprising an alkali metal and a crystalline phase, wherein the crystalline phase occupies 20 wt% or more of the core composition; and one or more of the following:

(a) a stress profile including an inflection point at a depth of 3 microns or more;

(b) a stress profile, comprising: a first compressive stress at the first surface of 200MPa or greater; and a second compressive stress at the inflection point of 20MPa or greater; or

(c) A non-sodium oxide having a non-zero concentration that varies from the first surface to a depth of layer of the non-sodium oxide; and a stress distribution including an inflection point and a depth of compression (DOC) located at 0.10t or more.

2. The glass-ceramic article of any one of the preceding claims, wherein the alkali metal of the central composition is lithium.

3. The glass-ceramic article of any one of the preceding claims, wherein the surface concentration of the crystalline phase at the first and second surfaces is within about 1% of the crystalline phase in the central composition, and wherein a glassy surface layer is absent.

4. The glass-ceramic article of any one of the preceding claims, wherein the crystalline phase comprises a petalite crystalline phase and/or a lithium silicate crystalline phase, wherein the lithium silicate crystalline phase is a lithium disilicate crystalline phase.

5. The glass-ceramic article of any one of the preceding claims, wherein the glass-ceramic substrate comprises a lithium-containing aluminosilicate glass-ceramic having a β -spodumene solid solution crystalline phase.

6. The glass-ceramic article of any one of the preceding claims, wherein the center composition comprises, by weight: 55 to 80% SiO₂2 to 20% Al₂O₃0.5 to 6% P₂O₅5 to 20% Li₂O, 0 to 5% Na₂O, 0.2 to 15% ZrO₂0 to 10B₃O₃And 0 to 10% ZnO.

7. The glass-ceramic article of any one of the preceding claims, wherein the stress profile comprises:

a spike region extending from the first surface to an inflection point; and

a tail region extending from the inflection point to a center of the glass-ceramic article;

wherein all points of the stress distribution in the peak region comprise a tangent value of 20 MPa/micron or greater and all points of the stress distribution in the tail region comprise a tangent value of 2 MPa/micron or less.

8. The glass-ceramic article of any one of the preceding claims, wherein the inflection point comprises a compressive stress of 50MPa or greater.

9. The glass-ceramic article of any one of the preceding claims, wherein lithium is present at the first and/or second surface in a non-zero concentration.

10. The glass-ceramic article of any one of the preceding claims, wherein t is 50 micrometers to 5 millimeters.

11. The glass-ceramic article of any one of the preceding claims, wherein at least one of:

(i) after the washing treatment, the difference between the color parameter a value measured according to the CIELAB color coordinate system and the color parameter a value before the exposure to the washing treatment is within 0.05 units, wherein the washing treatment comprises exposing the glass ceramic article to a washing solution having a pH of 2 to 12 for 30 minutes.

(ii) After a washing treatment, the difference between the color parameter b values measured according to the CIELAB color coordinate system and the color parameter b values before exposure to the washing treatment is within 0.5 units, wherein the washing treatment comprises exposing the glass ceramic article to a washing solution having a pH of 2 to 12 for 30 minutes; or

(iii) After the washing treatment, the color parameter L values measured according to the CIELAB color coordinate system are within 1 unit of the color parameter L values before exposure to the washing treatment, wherein the washing treatment comprises exposing the glass-ceramic article to a washing solution having a pH of 2 to 12 for 30 minutes.

12. The glass-ceramic article of any one of the preceding claims, wherein a surface waveguide is present from the first and/or second surface to the DOL.

13. The glass-ceramic article of any one of the preceding claims, wherein t is 50 micrometers to 5 millimeters.

14. A consumer electronic product, comprising:

a housing having a front surface, a back surface, and side surfaces;

an electronic assembly at least partially provided within the housing, the electronic assembly including at least a controller, a memory, and a display, the display being provided at or adjacent to the front surface of the housing; and

a cover disposed over the display;

wherein a portion of at least one of the casing or the cover glass comprises the glass-ceramic article of any preceding claim.

15. A method of making a glass-ceramic article, comprising:

exposing a glass-ceramic substrate having a base composition comprising lithium and a crystalline phase to an ion exchange treatment to form a glass-ceramic article based, the glass-ceramic substrate having opposing first and second surfaces defining a substrate thickness (t), wherein the ion exchange treatment comprises:

a first ion exchange process comprising a first bath comprising first metal ions having an atomic radius greater than that of lithium; and

a second ion exchange treatment comprising a second bath, the second bath comprising the first metal ions and second metal ions, performed after the first ion exchange treatment;

wherein the first metal ions of the first bath are present in a higher percentage than the first ions in the second bath.

16. The method of claim 15, wherein the glass-ceramic substrate comprises a lithium-containing aluminosilicate glass-ceramic having a β -spodumene solid solution crystalline phase.

17. The method of claim 15, wherein the crystalline phase comprises a petalite crystalline phase and/or a lithium silicate crystalline phase.

18. The method of any one of claims 15-17, wherein in the first bath, the first bath comprises an amount of the first metal ion of 97 wt% or more, and the second bath comprises an amount of the first metal ion of between about 80 wt% and less than 97 wt%.

19. The method of any of claims 15-18, wherein the first metal ion comprises potassium, and the first bath comprises potassium nitrate (KNO)₃) Is 97 to 100% by weight, and the second bath comprises potassium nitrate (KNO)₃) Is between about 80 wt.% and less than 97 wt.% and comprises sodium nitrate (NaNO)₃) The amount of (b) is 3 to 20 wt%.

20. The method of any one of claims 15-19, wherein the glass-ceramic article has a stress profile comprising a depth of compression (DOC) at 0.17t or greater.

21. The method of any of claims 15-20, wherein the first metal ion has a non-zero concentration that varies from the first surface to a depth of layer (DOL) relative to the first metal ion, and wherein the first metal ion is selected from the group consisting of: potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), silver (Ag), gold (Au), and copper (Cu).

22. The method of any one of claims 15-21, wherein the first ion exchange treatment and/or the second ion exchange treatment further comprises a dose of a lithium salt added to the first bath and/or the second bath, and wherein the lithium salt comprises lithium nitrate (LiNO) in an amount of 0.1 to 1 wt% in the first bath and/or the second bath₃) And (4) dosage.

23. The method of claim 21 or 22, wherein the surface concentration of the crystalline phase at the first and second surfaces is within about 1% of the crystalline phase in the base composition.

24. The method of any one of claims 15-23, wherein at least one of:

(a) the first ion exchange treatment, the second ion exchange treatment, or both further include sodium nitrite (NaNO) in an amount of 0.1 to 1 wt% in the first bath and/or the second bath₂) The dosage; or

(b) The first ion exchange treatment, the second ion exchange treatment, or both further include a trisodium phosphate (TSP) dosage in an amount of 0.1 to 1 weight percent in the first bath and/or the second bath.

25. The method of any one of claims 15-24, wherein t is 50 microns to 5 millimeters.

Technical Field

Embodiments of the present disclosure generally relate to glass-ceramic articles and high strength glass-ceramic articles with improved stress distribution and methods of making the same.

Background

The glass-ceramic article may be chemically strengthened, for example by ion exchange, to improve mechanical properties such as crack penetration and drop resistance. Glass-ceramics are multiphase materials having one or more crystalline phases and a residual glass phase, where the ion exchange process can be complex. In addition to affecting the residual glass phase, ion exchange can also affect one or more of the crystalline phases.

Chemical treatment is a strengthening method to impart a desirable/engineered stress profile with one or more of the following parameters: compressive Stress (CS), depth of compression (DOC), and maximum Center Tension (CT). Many glass-ceramic articles (including those having a processed stress profile) have a compressive stress that is highest or at a peak at the glass surface and decreases from the peak away from the surface and is zero stress at some internal location of the glass article before the stress in the glass article becomes tensile. Chemical strengthening by ion exchange (IOX) of alkali-containing glass-ceramics is one method in the art.

Generally, in a lithium (Li) -based glass substrate, two ions (sodium (Na) and potassium (K)) are used to perform diffusion and form a stress distribution. In such IOX processes, both K, Na and Li diffuse and exchange occurs simultaneously. Generally, K, which is a larger ionic radius, induces a higher stress, but diffuses slowly compared to Na ions of smaller ionic radius, which induce a lower stress. For this reason, it can be challenging to induce high stresses at moderate depths when using mixed K/Na salt baths. The K ions define what is called the profile peak, while the Na ions define the deep tail of the profile.

For glass-ceramic article applications, there is a continuing need for glass-ceramic articles having reliable mechanical and/or chemical properties. There is a particular need for strengthening lithium-containing glass-ceramic articles with potassium, which exhibits improved mechanical and/or chemical reliability for their industry. There is also a continuing need to implement it in an efficient and cost-effective manner.

Disclosure of Invention

Aspects of the present disclosure pertain to glass-ceramic articles and methods of their manufacture and use.

In aspect 1, the glass-ceramic article comprises: a glass-ceramic substrate having opposing first and second surfaces defining a substrate thickness (t); a core composition at the center of the glass-ceramic article comprising an alkali metal and a crystalline phase, wherein the crystalline phase occupies 20 wt% or more of the core composition; and a stress distribution including an inflection point at a depth of 3 micrometers or more.

In aspect 2, the glass-ceramic article comprises: a glass-ceramic substrate having opposing first and second surfaces defining a substrate thickness (t); a core composition at the center of the glass-ceramic article comprising an alkali metal and a crystalline phase, wherein the crystalline phase occupies 20 wt% or more of the core composition; and a stress profile comprising a first compressive stress at the first surface of 200MPa or greater; and a second compressive stress at the inflection point of 20MPa or greater.

In aspect 3, the glass-ceramic article comprises: a glass-ceramic substrate having opposing first and second surfaces defining a substrate thickness (t); a core composition at the center of the glass-ceramic article comprising an alkali metal and a crystalline phase, wherein the crystalline phase occupies 20 wt% or more of the core composition; a non-sodium oxide having a non-zero concentration that varies from the first surface to a depth of layer of the non-sodium oxide; and a stress distribution including an inflection point and a depth of compression (DOC) located at 0.10t or more.

Aspect 4 according to any preceding aspect, wherein the alkali metal of the central composition is lithium.

Aspect 5 according to any preceding aspect, wherein the crystalline phase is present in an amount of 20 wt% to about 70 wt% of the central composition.

Aspect 6 according to any preceding aspect, wherein the surface concentration of the crystalline phase at the first and second surfaces is within about 1% of the crystalline phase in the central composition.

Aspect 7 according to any preceding aspect, wherein a glassy surface layer is absent.

Aspect 8 according to any preceding aspect, wherein the crystalline phase comprises a petalite crystalline phase and/or a lithium silicate crystalline phase.

Aspect 9 according to any preceding aspect, wherein the lithium silicate crystal phase is a lithium disilicate crystal phase.

Aspect 10 according to any preceding aspect, wherein the glass-ceramic substrate comprises a lithium-containing aluminosilicate glass-ceramic having a β -spodumene solid solution crystalline phase.

Aspect 11 according to any preceding aspect, wherein the centre group is by weightThe method comprises the following steps: 55 to 80% SiO₂2 to 20% Al₂O₃0.5 to 6% P₂O₅5 to 20% Li₂O, 0 to 5% Na₂O, 0.2 to 15% ZrO₂0 to 10B₃O₃And 0 to 10% ZnO.

Aspect 12 according to any preceding aspect, wherein the stress distribution comprises: a spike region extending from the first surface to the inflection point; and a tail region extending from the inflection point to a center of the glass-ceramic article; wherein all points of the stress distribution in the peak region comprise a tangent value of 20 MPa/micron or greater and all points of the stress distribution in the tail region comprise a tangent value of 2 MPa/micron or less.

Aspect 13 according to any preceding aspect, wherein the inflection point comprises a compressive stress of 50MPa or greater.

Aspect 14 according to any preceding aspect, comprising a first metal oxide having a non-zero concentration that varies from the first surface to a depth of layer (DOL) relative to the first metal oxide.

Aspect 15 according to any preceding aspect, wherein the first metal oxide is selected from the group consisting of: potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), silver (Ag), gold (Au), and copper (Cu).

Aspect 16 according to aspect 14 or 15, wherein the first metal oxide is potassium.

Aspect 17 according to any preceding aspect, wherein lithium is present at the first and/or second surface in a non-zero concentration.

Aspect 18 according to any preceding aspect, wherein t is 50 microns to 5 millimeters.

In aspect 19, the glass-ceramic article comprises: a glass-ceramic substrate having opposing first and second surfaces defining a substrate thickness (t) and a central composition at a center of the glass-ceramic article, comprising lithium and a crystalline phase, wherein the crystalline phase occupies 20 wt.% or more of the central composition; potassium oxide having a non-zero concentration that varies from the first and/or second surface to a depth of layer (DOL) of potassium oxide; a stress profile, comprising: a depth of compression (DOC) greater than or equal to about 0.17 t; a first compressive stress at the first surface of 200MPa or greater; a second compressive stress at the inflection point of 20MPa or greater; and a spike region extending from the first surface to the inflection point, wherein the inflection point is located at a depth of 5 microns or more.

Aspect 20 according to aspect 19, wherein the glass-ceramic substrate comprises a lithium-containing aluminosilicate glass-ceramic having a β -spodumene solid solution crystalline phase.

Aspect 21 according to aspect 19, wherein the crystalline phase comprises a petalite crystalline phase and/or a lithium silicate crystalline phase.

Aspect 22 according to any one of aspects 19-21, wherein the center composition comprises, by weight: 55 to 80% SiO₂2 to 20% Al₂O₃0.5 to 6% P₂O₅5 to 20% Li₂O, 0 to 5% Na₂O, 0.2 to 15% ZrO₂0 to 10B₃O₃And 0 to 10% ZnO.

Aspect 23 according to any one of aspects 19-22, wherein after the washing treatment, the color parameter a value measured according to the CIELAB color coordinate system is within 0.05 units of the color parameter a value before exposure to the washing treatment, wherein the washing treatment comprises exposing the glass-ceramic article to a washing solution having a pH of 2 to 12 for 30 minutes.

Aspect 24 according to any one of aspects 19-23, wherein after the washing treatment, the color parameter b values measured according to the CIELAB color coordinate system are within 0.5 units of the color parameter b values prior to exposure to the washing treatment, wherein the washing treatment comprises exposing the glass ceramic article to a washing solution having a pH of 2 to 12 for 30 minutes.

Aspect 25 according to any one of aspects 19-24, wherein after the washing treatment, the value of the color parameter L measured according to the CIELAB color coordinate system is within 1 unit of the value of the color parameter L prior to exposure to the washing treatment, wherein the washing treatment comprises exposing the glass-ceramic article to a washing solution having a pH of 2 to 12 for 30 minutes.

Aspect 26 according to any one of aspects 19-15, wherein the surface concentration of the crystalline phase at the first and second surfaces is within about 1% of the crystalline phase in the central composition.

Aspect 27 according to any one of aspects 19-26, wherein a glassy surface layer is absent.

An aspect 28 according to any one of aspects 19-27, wherein there is a surface waveguide from the first and/or second surface to the DOL.

Aspect 29 according to any one of aspects 19-28, wherein t is 50 microns to 5 millimeters.

In aspect 30, the consumer electronic product includes: a housing having a front surface, a back surface, and side surfaces; an electronic assembly provided at least partially within the housing, the electronic assembly including at least a controller, a memory, and a display, the display provided at or adjacent to the front surface of the housing; and a cover disposed over the display; wherein a portion of at least one of the housing and the cover comprises the glass-ceramic article of any preceding aspect.

In aspect 31, a method of making a glass-ceramic article comprises: exposing a glass-ceramic substrate having a base composition comprising lithium and a crystalline phase to an ion exchange treatment to form a glass-ceramic article, the glass-ceramic substrate having opposing first and second surfaces defining a substrate thickness (t), wherein the ion exchange treatment comprises: a first ion exchange process comprising a first bath comprising first metal ions having an atomic radius greater than that of lithium; and a second ion exchange treatment performed after the first ion exchange treatment, comprising a second bath comprising the first metal ions and second metal ions; wherein the first metal ions of the first bath are present in a higher percentage than the first ions in the second bath.

Aspect 32 according to aspect 31, wherein the glass-ceramic substrate comprises a lithium-containing aluminosilicate glass-ceramic having a β -spodumene solid solution crystalline phase.

Aspect 33 according to aspect 31, wherein the crystalline phase comprises a petalite crystalline phase and/or a lithium silicate crystalline phase.

Aspect 34 according to any one of aspects 31-33, wherein in the first bath comprises the first metal ion in an amount of 97 wt.% or more and the second bath comprises the first metal ion in an amount of between about 80 wt.% and less than 97 wt.%.

Aspect 35 according to any one of aspects 31-34, wherein the first metal ions comprise potassium and the first bath comprises potassium nitrate (KNO)₃) Is 97 to 100% by weight, and the second bath comprises potassium nitrate (KNO)₃) Is between about 80 wt.% and less than 97 wt.% and comprises sodium nitrate (NaNO)₃) The amount of (b) is 3 to 20 wt%.

The aspect 36 of any of aspects 31-35, wherein the glass-ceramic article has a stress profile comprising a depth of compression (DOC) at 0.17t or greater.

An aspect 37 according to any one of aspects 31-36, wherein the first metal ions have a first non-zero concentration that varies from the first surface to a depth of layer (DOL) relative to the first metal ions.

Aspect 38 according to aspect 37, wherein the first metal ion is selected from the group consisting of: potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), silver (Ag), gold (Au), and copper (Cu).

Aspect 39 according to any one of aspects 31-38, wherein the first ion exchange treatment and/or the second ion exchange treatment further comprises a dose of a lithium salt added to the first bath and/or the second bath.

Aspect 40 according to aspect 39, wherein the lithium salt comprises lithium nitrate (LiNO)₃) The amount of its dose in the first and/or second bath is 0.1 to 1 wt%.

Aspect 41 according to any one of aspects 39 or 40, wherein the surface concentration of the crystalline phase at the first and second surfaces is within about 1% of the crystalline phase in the base composition.

Aspect 42 according to any one of aspects 31-41, wherein the first ionThe exchange treatment, the second ion exchange treatment, or both further include sodium nitrite (NaNO) in an amount of 0.1 to 1 wt% in the first bath and/or the second bath₂) And (4) dosage.

Aspect 43 according to any one of aspects 31-42, wherein the first ion exchange treatment, the second ion exchange treatment, or both further comprise a trisodium phosphate (TSP) dose in an amount of 0.1 to 1 wt.% in the first and/or second bath.

Aspect 44 according to any one of aspects 31-43, wherein t is 50 microns to 5 millimeters.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments described below.

FIG. 1A is a plan view of an exemplary electronic device incorporating any of the glass-based articles disclosed herein;

FIG. 1B is a perspective view of the exemplary electronic device of FIG. 1A;

FIG. 2 is an image of TM and TE guided-mode spectral fringes of a glass-ceramic article after a first IOX treatment;

FIG. 3 is an image of TM and TE guided-mode spectral fringes of a glass-ceramic article after a second IOX treatment according to an embodiment;

FIG. 4 is an image of TM and TE guided-mode spectral fringes of a glass-ceramic article after a first IOX treatment;

FIG. 5 is an image of TM and TE guided-mode spectral fringes of a glass-ceramic article after a second IOX treatment according to an embodiment;

FIG. 6 is an image of TM and TE guided-mode spectral fringes of a glass-ceramic article after a first IOX treatment;

FIG. 7 is a stress distribution of stress (MPa) versus position (microns) of the glass-ceramic article of FIG. 6 after the first IOX treatment;

FIG. 8 is an image of TM and TE guided-mode spectral fringes of a glass-ceramic article after dual IOX treatment according to an embodiment;

FIG. 9 is a stress distribution of stress (MPa) versus position (microns) of the glass-ceramic article of FIG. 8 after a dual IOX treatment;

FIG. 10 is an image of TM and TE guided-mode spectral fringes of a glass-ceramic article after a first IOX treatment;

FIG. 11 is an image of TM and TE guided-mode spectral fringes of a glass-ceramic article after a second IOX treatment;

FIG. 12 is a plot of lithium concentration for the second IOX bath as a function of profile for the first IOX bath and Central Tension (CT);

fig. 13 is a color measurement plot based on the CIELAB color coordinate system showing variability of the L parameter for various treatment types;

fig. 14 is a color measurement plot based on the CIELAB color coordinate system showing the variability of the a parameter for various treatment types; and

fig. 15 is a color measurement plot based on the CIELAB color coordinate system showing the variability of the b parameter for various treatment types.

Detailed Description

Before describing several exemplary embodiments, it is to be understood that the present disclosure is not limited to the details of construction or process steps set forth in the following disclosure. The disclosure provided herein is capable of other embodiments and of being practiced or being carried out in various ways.

Reference throughout this specification to "one embodiment," "certain embodiments," "various embodiments," "one or more embodiments," or "an embodiment" means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, appearances of the phrases such as "in one or more embodiments," "in certain embodiments," "in various embodiments," "in one embodiment," or "in an embodiment" in various places throughout this specification are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

Defining and measuring techniques

As used herein, the term "glass-ceramic" is a solid prepared by controlled crystallization of a precursor glass, which has one or more crystalline phases and a residual glass phase.

As used herein, a "glassy" region or layer refers to a surface region having a lower percentage of crystals than the inner region. The glassy region or layer may be formed by: (i) decrystallization of one or more crystalline phases of the glass-ceramic article during ion exchange; (ii) laminating or fusing glass to glass-ceramic; or (iii) other means known in the art, such as formation while ceramizing a precursor glass into a glass ceramic.

The "base composition" is the chemical makeup of the substrate prior to being subjected to any ion exchange (IOX) treatment. That is, the base composition is not doped with any ions from IOX. The composition at the center of the IOX-treated glass-based article is generally the same as the base composition when the IOX treatment conditions are such that the IOX-supplied ions do not diffuse into the center of the substrate. In one or more embodiments, the composition at the center of the glass article comprises a base composition.

It is noted that the terms "substantially" and "about" may be used herein to represent the degree of inherent uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. The terms "comprises," "comprising," and any other variation thereof, are intended to cover a non-exclusive inclusion, such that a non-exclusive inclusion does not imply that all of the features and functions of the subject matter claimed herein are in fact, or even wholly, essential to the subject matter. Thus, for example, a glass-based article that is substantially free of "MgO" is one in which MgO is not actively added or dosed to the glass-based article, but may be present in very small amounts (e.g., less than 0.01 mole%) as a contaminant.

Unless otherwise indicated, all compositions described herein are expressed in weight percent (wt%) based on oxides.

"stress distribution" is the stress relative to the position of the glass-based article or any portion thereof. The compressive stress region extends from the first surface of the article to a depth of compression (DOC), at which point the article is under compressive stress. The central tension region extends from the DOC to a region that includes the article under tensile stress.

As used herein, depth of compression (DOC) refers to the depth at which the stress within the glass-ceramic article changes from compressive to tensile. At the DOC, the stress transitions from positive (compressive) stress to negative (tensile) stress, thus exhibiting a zero stress value. According to the common practice in the mechanical field, compression is expressed as negative stress: (<0) And tensile as normal stress: (>0). However, throughout this specification, the Compressive Stress (CS) is expressed as a positive value or an absolute value, i.e., CS ═ CS |, as set forth herein. Furthermore, the tensile stress is expressed herein as negative stress: (<0) Or in some cases, tensile stress is specified as an absolute value. Central Tension (CT) refers to the tensile stress in the central region or central tension region of a glass-based article. Maximum central tension (maximum CT or CT)_{Maximum value}) Occurs in the central tension zone and is typically located at 0.5t, where t is the article thickness. Reference to the exact center of the position at "nominal" 0.5t allows variation with respect to the maximum tensile stress.

The "knee" of the stress distribution is the depth of the article where the slope of the stress distribution transitions from steep to gradual. An inflection point may represent a transition region over a span of depths where the slope changes. The inflection depth is measured as the depth of layer at which the largest ions have a concentration gradient in the article. The CS of the inflection point is the CS at the inflection point depth.

As used herein, the terms "exchange depth", "depth of layer" (DOL), "chemical depth of layer" and "depth of chemical layer" may be used interchangeably to generally describe the depth of ion exchange driven by the ion exchange process (IOX) for a particular ion. DOL refers to the following depth within the glass-ceramic article (i.e., the distance from the surface of the glass-ceramic article to its interior region): there, ions of the metal oxide or alkali metal oxide (e.g., metal ions or alkali metal ions) diffuse into the glass-ceramic article where the concentration of ions reaches a minimum as measured by a surface stress meter (FSM) using commercially available equipment (e.g., FSM-6000, manufactured by Orihara industries, ltd., japan). In some embodiments, the DOL is given as the exchange depth of the slowest diffusing ion or the largest ion introduced by the ion exchange (IOX) process.

The non-zero metal oxide concentration that varies from the first surface to the depth of layer (DOL) relative to the metal oxide, or at least along a majority of the article thickness (t), indicates that stress has been generated in the article as a result of the ion exchange. The change in metal oxide concentration may be referred to herein as a metal oxide concentration gradient. A metal oxide that is non-zero in concentration and varies from the first surface to the DOL or along the thickness of a portion can be described as creating a stress in the glass-based article. By chemically strengthening the glass-based substrate, wherein a plurality of first metal ions are exchanged with a plurality of second metal ions in the glass-based substrate, a concentration gradient or change in the metal oxide is created.

Unless otherwise specified, units of CT and CS herein are megapascals (MPa), while units of thickness and DOC are millimeters or micrometers (um).

DOC values and maximum Central Tension (CT) values were measured using a scattered light polarizer (scapp) from glass stress ltd, located in Tallinn, Estonia.

The surface CS measurement method depends on whether a glassy region or layer is formed at the surface of the glass-ceramic article during ion exchange. If no vitreous layer or region is present, surface CS is measured by a surface stress meter (FSM) using a commercial instrument (FSM-6000, for example) manufactured by Orihara Industrial Co., Ltd. (Japan). Surface stress measurement relies on the accurate measurement of the Stress Optical Coefficient (SOC), which is related to the birefringence of the glass. The SOC was then measured according to protocol C (Method of Glass disks) described in ASTM Standard C770-16, entitled "Standard Test Method for measuring Glass Stress-Optical Coefficient", which is incorporated herein by reference in its entirety. If a glassy region or layer is formed, the surface CS (and CS in the glassy layer or region) is measured as follows: in prism coupling measurements, the depth of layer of the glassy region is measured by the birefringence of the first transmission (coupling) resonance of the glassy region, and by the separation between the first and second transmission resonances or the width of the first transmission resonance.

The CS in the remaining CS region is measured by the Refracted Near Field (RNF) method described in U.S. Pat. No. 8,854,623 entitled "Systems and methods for measuring a profile characterization of a glass sample," the entire disclosure of which is incorporated herein by reference. The RNF measurement is force balanced and is calibrated by the maximum CT value provided by the scale measurement. Specifically, the RNF method includes placing a glass article proximate to a reference block, generating a polarization-switched light beam (which switches between orthogonal polarizations at a rate of 1Hz to 50 Hz), measuring an amount of power in the polarization-switched light beam, and generating a polarization-switched reference signal, wherein the measured amounts of power in each of the orthogonal polarizations are within 50% of each other. The method further includes passing the polarization-switched beam through the glass sample and the reference block into the glass sample at different depths, and then delaying the passed polarization-switched beam with a delay optical system to a signal photodetector that generates a polarization-switched detector signal. The method further comprises the following steps: dividing the detector signal by the reference signal to form a normalized detector signal, and determining the profile characteristic of the glass sample from the normalized detector signal.

The stress distribution can be measured by a combination of RNF for the inner CS, scapp for the CT region, and methods for measuring the surface CS.

According to aspects and/or embodiments of the present disclosure, CIELAB color space coordinates (e.g., CIE L, CIE a, and CIE b, CIE L, a, and b, or L, a, and b) for describing the color of the glass-ceramic article are determined as follows: transmission and total reflection (including specular reflection) were measured at 10 ° observer using an x-rite color i7 spectrophotometer by illuminant D65, a and F2, and then the L, a and b color space coordinates were calculated by CIELAB standard.

Dual ion exchange (DIOX) treatment

The glass-ceramic articles disclosed herein have improved stress distribution. The article is prepared by diffusion using a modified two-step ion exchange (DIOX) which: (1) first introducing a spike in a spike region of the stress profile, for example by using a bath in a first treatment, the bath comprising a first metal ion (e.g., potassium) having an atomic radius greater than that of lithium; followed by (2) a second treatment of diffusion to maintain spikes and form tail regions of stress distribution, for example by using the first and second metal ions of the first bath (e.g., a potassium-sodium mixed bath). The stress distribution resulting from the methods herein is stable and controllable in a material (e.g., a glass-ceramic that may contain a crystalline form of lithium disilicate as one of its components).

In some embodiments, the first step of DIOX results in: a distinct spike region in the surface of the glass, plus an attenuated tail of the stress distribution toward the center of the article. Stress spikes/potassium at and below the surface form a waveguide that facilitates reproducible and reliable measurement of waveguide modes and determination of Compressive Stress (CS) and spike depth in the surface. The second step forms the tail region of the stress distribution without disturbing the spike region. Employing, for example, 50 wt.% KNO, as compared to prior art DIOX processes for forming glass-ceramic articles (which typically rely on a first step to create a stress distribution within a substrate)₃50% by weight NaNO₃Bath (380 ℃ for 4 hours); a second step is then used to impart a spike in the surface, using, for example, 90 wt.% KNO₃10 wt.% NaNO₃Bath (20 minutes)), the process herein is in reverse order.

In glass-ceramic substrates containing lithium and crystalline phases (e.g., petalite and/or lithium silicate phases), potassium diffuses significantly more slowly than sodium, not only due to the different ionic radii, but also due to the presence of crystalline material in the substrate. This means that very long diffusion times are usually required to produce spikes in the near surface. Furthermore, in the case of some specific glass-ceramics, sodium diffuses into the glass as it diffuses into the glassIn such a material, the following phenomenon occurs. As sodium diffuses into the material, a portion of the sodium exchanges with the lithium available in the substrate, but another portion exchanges with lithium-based nanocrystals (e.g., lithium disilicate (Li) in glass-ceramic structures₂Si₂O₅And other forms thereof)) occurs. The net result is partial dissolution of the nanocrystals, which produces a glassy Na-doped silicate glass layer appearance. Due to the kinetics of the diffusion process, this glassy layer is present in the surface of the material undergoing ion exchange, with an amorphous content that gradually decreases towards the centre of the article. The thickness of this vitreous layer will depend on the amount of sodium, the time and temperature used for the diffusion process.

In practice, a Na-rich glassy layer, from the order of a few nanometers to tens of micrometers (e.g., hundreds of nanometers up to a thickness of 4 micrometers) is achieved by Na ion exchange in these glass-ceramics. This glassy layer, which has a lower index of refraction than the underlying glass-ceramic substrate, prevents optical coupling of the prism for use in stress metrology via FSM-6000LE instruments. As a result, the fringes become blurred and/or turbid, making it difficult, if not impossible, to accurately measure the stress at the surface without improvement of the metrology technique/apparatus. Embodiments of the present disclosure can tolerate some amount of blurring at the surface due to the presence of a Na-rich layer (not considered a vitreous layer), which is the minimum thickness that still enables detection and measurement of streaks. Thus, in some embodiments, the glass-ceramic articles disclosed herein do not have a vitreous layer.

In some embodiments, to avoid the formation of a vitreous layer, the DIOX treatment disclosed herein may be further strengthened by: a low percentage of Li is added to the one or two step bath, which deviates from any initial pure bath conditions. That is, by adding a low percentage of Li to begin producing a nominal lithium "poison" or "dose" rather than waiting for Li diffusion from the underlying substrate, formation of a glassy layer that is detrimental to process control is mitigated or avoided. The resulting in-process and final samples are more homogeneous than would otherwise be the caseConsistent metrology conditions and process control (e.g., bath composition, bath temperature, and duration of ion exchange treatment) are facilitated. That is, the stress is measurable for the first glass batch that was ion exchanged. In some embodiments, Li may be introduced in the form of a lithium-containing salt, including but not limited to LiNO₃And LiNO₂。

In addition, by introducing some NaNO into the ion exchange bath₂The DIOX treatment can be further enhanced. This is to produce better salt mixing uniformity and to reduce the amount of impurities (e.g., magnesium ions) that remain part of the salt due to decomposition.

The entire protocol herein proceeds in a manner opposite to the common protocol, creating stresses in the glass and glass-ceramic via two-step ion exchange.

In some embodiments, the first IOX treatment herein involves the use of a bath (100 wt% KNO)₃Or nearly 100% of ions greater than Li (and optionally greater than Na) produce spikes in the article in question (e.g., lithium-containing aluminosilicate glass-ceramics). In some embodiments, the bath for the first ion exchange treatment comprises NaNO₂And lithium salt (e.g., LiNO)₃Or LiNO₂) Thereby avoiding the formation of a vitreous layer and improving bath chemistry. In this case, the diffusion is long and produces a reasonable spike. Instead of or in combination with potassium, other elements may be used in the first IOX treatment, such as: rubidium, cesium, francium, copper, silver, gold, etc. to enhance the stress value. In one or more embodiments, the metal ions of the first bath are larger than lithium. In some embodiments, the metal ions of the first bath are larger than sodium. In some embodiments, the metal ion of the first bath is potassium.

In some embodiments, the second IOX treatment herein involves creating a tail of the stress profile with a bath in which ions greater than Li (and optionally greater than Na) are not 100%. In one or more embodiments, the ratio is 90 wt.% KNO₃And 10% by weight NaNO₃This is in contrast to conventional processes. This results in deep regions of distribution (distributed) due to Na exchange with LiTail) generates a significant amount of stress. Furthermore, the stress in the surface experienced a small drop, but a continuous increase in the spike depth was also observed. This increase in spike depth enables more fringes or more spaced apart fringes to be formed for detection and measurement via FSM-6000LE instruments. Further, in some embodiments, in the second step, the bath for the second ion exchange treatment comprises NaNO₂And lithium salt (e.g., LiNO)₃Or LiNO₂) Thereby reducing or avoiding the formation of a vitreous layer and improving bath chemistry, similar to the first step.

In one or more embodiments, the lithium-containing salt (e.g., LiNO) in the first and/or second bath₃Or LiNO₂) The amount of (b) is 0.1 to 1 wt% or 0.2 to 0.5 wt% of the amount of the first bath and/or the second bath.

In one or more embodiments, the NaNO in the first and/or second bath₂The amount of (b) is 0.1 to 1 wt% or 0.2 to 0.5 wt% of the amount of the first bath and/or the second bath.

Other salt concentration ratios are also possible in the second ion exchange treatment, for example: 80% by weight KNO₃And 20% by weight NaNO₃. As the amount of potassium decreases in the second step, there may be a small depression in the refractive index and making stress measurements more difficult. In addition, the stress at the surface also decreases proportionally.

In the glass-ceramic article, there is a metal oxide (e.g., K, Rb, Cs, Ag, etc.) other than lithium that is not present in the base composition of the glass-ceramic substrate, having a non-zero concentration that varies from the first surface to a depth of layer (DOL) relative to the metal oxide. The stress distribution is created due to a non-zero concentration of the metal oxide that varies from the first surface. The non-zero concentration may vary along a portion of the thickness of the article. In some embodiments, the concentration of the metal oxide is non-zero and varies along a thickness range from about 0t to about 0.3 t. In some embodiments, the concentration of metal oxide is non-zero and varies along the following thickness ranges: from about 0t to about 0.35t, from about 0t to about 0.4t, from about 0t to about 0.45t, from about 0t to about 0.48t, or from about 0t to about 0.50 t. The variation in concentration may be continuous along the thickness range described above. The concentration variation may include a metal oxide concentration variation of about 0.2 mole% or greater along a thickness segment of about 100 microns. The variation in metal oxide concentration along the thickness segment of about 100 microns may be about 0.3 mole% or greater, about 0.4 mole% or greater, or about 0.5 mole% or greater. This change can be measured by methods known in the art, including microprobes.

In some embodiments, the concentration variation may be continuous along a thickness segment of about 10 microns to about 30 microns. In some embodiments, the concentration of the metal oxide decreases from the first surface to a point located between the first surface and the second surface, and increases from the point to the second surface.

In some embodiments, more than one metal oxide (e.g., Na)₂O and K₂Combination of O) may vary from the first surface to a depth of layer (DOL) relative to the metal oxide. In some embodiments, when the concentrations of the two metal oxides are varied and when the radii of the ions are different from each other, at a shallow depth, the concentration of the ions having the larger radius is greater than the concentration of the ions having the smaller radius, and at a deeper depth, the concentration of the ions having the smaller radius is greater than the concentration of the ions having the larger radius. This is due in part to the size of the monovalent ions that are exchanged into the glass-ceramic with the smaller monovalent ions. In such glass-ceramic articles, the larger ions (i.e., K) are present at or near the surface due to the greater amount⁺Ions), the region at or near the surface includes a larger CS. Furthermore, the slope of the stress distribution generally decreases with distance from the surface due to the nature of the concentration distribution achieved by chemical diffusion from a fixed surface concentration.

In one or more embodiments, the metal oxide concentration gradient extends through a majority of the article thickness t. In some embodiments, the concentration of the metal oxide can be about 0.5 mole% or greater (e.g., about 1 mole% or greater) along the entire thickness of the gradient and is greatest at the first and/or second surfaces (0t) and decreases substantially constantly to a point between the first and second surfaces. At this point, the concentration of metal oxide is minimal along the entire thickness t; however, the concentration is also non-zero at this point. In other words, the non-zero concentration of the particular metal oxide extends along a majority of the thickness t (as described herein) or along the entire thickness t. The total concentration of the particular metal oxide in the glass-based article can be from about 1 mol% to about 20 mol%.

The concentration of the metal oxide can be determined by a baseline amount of the metal oxide in the glass-ceramic substrate that is ion-exchanged to form the glass-ceramic article.

Overview of glass-ceramic articles

The stress distribution achieved by the methods disclosed herein is unique. The stress distribution may include: a spike region extending from the first surface to the inflection point, and a tail region extending from the inflection point to a center of the glass-ceramic article.

An advantage of the glass-ceramic articles disclosed herein is that they have excellent strength and color consistency. The DIOX process enables stress measurements of glass ceramic samples during manufacturing, which would otherwise be very difficult to perform without modification to previously used instruments/methods. In some embodiments, the glass-ceramic article is free of a significant vitreous sodium layer near the surface. In one or more embodiments, the surface concentration of the crystalline phases at the first and second surfaces is within about 1% or 0.5% or 0.1% of the crystalline phases in the central composition as determined by X-ray diffraction (XRD) using Rietveld (Rietveld) analysis. In some embodiments, the glass-ceramic articles herein are stable to color. In one or more embodiments, the article retains one or more CIELAB color parameters: a, b and L, the values of which are such that the difference before and after the washing treatment is not visually detectable. In one or more embodiments, the washing treatment is a pH range of about 2 to about 12 for 30 minutes or more. In one or more embodiments, L is ± 1 unit or less, ± 0.75 unit or less, ± 0.5 unit or less, ± 0.25 unit or less. In one or more embodiments, a is ± 0.05 units or less, ± 0.04 units or less, ± 0.03 units or less, ± 0.2 units or less, ± 0.1 units or less. In one or more embodiments, b is ± 0.5 or less, ± 0.45 or less, ± 0.4 or less, ± 0.35 or less, ± 0.3 or less, ± 0.25 or less, ± 0.20 or less, ± 0.15 or less, ± 0.1 or less, or ± 0.05 or less. The color parameters are also stable for various pH values from 2 to 12 relative to an unwashed article.

The techniques may be used for any lithium-based glass-ceramic substrate. Other elements than potassium (K) that are not present in the substrate can also be introduced using the same technique, for example: rubidium (Rb), cesium (Cs), francium (Fr), silver (Ag), gold (Au), copper (Cu), and combinations thereof.

The range of depth of compression (DOC) may be: from greater than 0 × t to 0.3 × t, from greater than 0 × t to 0.25 × t, from greater than 0 × t to 0.2 × t, from 0.05 × t to 0.3 × t, from 0.05 × t to 0.25 × t, from 0.05 × t to 0.2 × t, from 0.1 × t to 0.3 × t, from 0.1 × t to 0.25 × t, from 0.1 × t to 0.2 × t, from 0.15 × t to 0.3 × t, from 0.15 × t to 0.25 × t, from 0.15 × t to 0.2 × t, from 0.17 × t to 0.3 × t, from 0.17 × t to 0.25 × t, from 0.15 × t to 0.2 × t, and from 0.17 × t to 0.3 × t, from 0.17 × t to 0.25 × t. In some embodiments, the DOC can be greater than or equal to 0.1t, 0.11t, 0.12t, 0.13t, 0.14t, 0.15t, 0.16t, 0.17t, or 0.175t, or 0.18t, or 0.188t, or deeper.

For potassium, the depth of layer (DOL) can be greater than or equal to 0.01t or greater, 0.02t or greater, 0.03t or greater, 0.04t or greater, or 0.05t or greater.

In one or more embodiments, all points of the stress distribution located in the spike region include tangents having an absolute value of 20 MPa/micron or greater. In one or more embodiments, the spike region includes a compressive stress of 200MPa or greater, at least from the first surface to a depth of 3 microns or greater.

In one or more embodiments, all points of the stress distribution located in the tail region include tangents having an absolute value of 2 MPa/micron or less.

The surface Compressive Stress (CS) at the first surface may be 200MPa or greater. CS may be in the following range: 200MPa to 1.2GPa, 400MPa to 950MPa, or about 800MPa, and all values and subranges therebetween. In one or more embodiments, the first compressive stress at a depth of about 5 to 10 microns from the first surface is 200MPa or greater.

The maximum Central Tension (CT) can be 30MPa or greater, 40MPa or greater, 45MPa or greater, or 50MPa or greater. The CT range may be 30MPa to 100MPa, and all values and subranges therebetween.

In some embodiments, the thickness t of the glass-ceramic article is in the range: 0.2mm to 5mm, 0.2mm to 4mm, 0.2mm to 3mm, 0.2mm to 2mm, 0.2mm to 1.5mm, 0.2mm to 1mm, 0.2mm to 0.9mm, 0.2mm to 0.8mm, 0.2mm to 0.7mm, 0.2mm to 0.6mm, 0.2mm to 0.5mm, 0.3mm to 5mm, 0.3mm to 4mm, 0.3mm to 3mm, 0.3mm to 2mm, 0.3mm to 1.5mm, 0.3mm to 1mm, 0.3mm to 0.9mm, 0.3mm to 0.8mm, 0.3mm to 0.7mm, 0.3mm to 0.6mm, 0.3mm to 0.5mm, 0.4mm to 5mm, 0.4mm to 4mm, 0.3mm to 0.8mm, 0.3mm to 0.7mm, 0.3mm to 0.6mm, 0.3mm to 0.5mm, 0.4mm, 0.5mm, 0.4mm to 5mm, 0.4mm, 0.8mm, 0.5mm, 0.4mm to 0.5mm, 0.4mm to 0.8mm, 0.5mm, 0.0.8 mm to 0.0.0.5 mm, 0.8mm to 0.5mm, 0.0.5 mm, 0.0.0.8 mm, 0.5mm, 0, 0.8mm to 3mm, 0.8mm to 2mm, 0.8mm to 1.5mm, 0.8mm to 1mm, 1mm to 2mm, 1mm to 1.5mm, and all ranges and subranges therebetween. In some embodiments, the glass-ceramic article can be substantially planar and flat. In other embodiments, the glass-ceramic article may be shaped, for example, may have a 2.5D or 3D shape. In some embodiments, the glass-ceramic article may have a uniform thickness, while in other embodiments, the glass-ceramic article may not have a uniform thickness.

Glass ceramic substrate

In one or more embodiments, the thickness t of the glass-ceramic substrate is from 200 micrometers to 5 millimeters, and all values and subranges therebetween.

Various different processes may be employed to provide the glass-ceramic substrate. The process for making a glass-ceramic comprises: the precursor glass is heat treated at one or more predetermined temperatures for one or more predetermined times to induce homogenization of the glass and crystallization (i.e., nucleation and growth) of one or more crystalline phases (e.g., having one or more compositions, amounts, geometries, sizes or size distributions, etc.). In some embodiments, the heat treatment may include: (i) heating the precursor glass at a rate of 1-10 ℃/minute to a pre-glass nucleation temperature; (ii) maintaining the crystallizable glass at the pre-glass nucleation temperature for a time period of from about 1/4 hours to about 4 hours to produce a pre-nucleated crystallizable glass; (iii) heating the pre-nucleated crystallizable glass to a nucleation temperature (Tn) at a rate of 1-10 ℃/minute; (iv) maintaining the crystallizable glass at the nucleation temperature for a period of time from about 1/4 hours to about 4 hours to produce a nucleated crystallizable glass; (v) heating the nucleated crystallizable glass to a crystallization temperature (Tc) at a rate of about 1 ℃ per minute to about 10 ℃ per minute; (vi) maintaining the nucleated crystallizable glass at the crystallization temperature for a time period of from about 1/4 hours to about 4 hours to produce a glass-ceramic as described herein; and (vii) cooling the formed glass-ceramic to room temperature. As used herein, the term crystallization temperature may be used interchangeably with ceramization temperature or ceramization temperature. Furthermore, the terms "ceramized" or "ceramized" in these embodiments may be used collectively to denote steps (v), (vi) and optionally (vii). In some embodiments, the pre-glass nucleation temperature may be 540 ℃, the nucleation temperature may be 600 ℃, and the crystallization temperature may be 630 ℃ to 730 ℃. In other embodiments, the heat treatment does not include maintaining the crystallizable glass at a pre-glass nucleation temperature. Thus, the heat treatment may comprise: (i) heating the precursor glass to a nucleation temperature (Tn) at a rate of 1-10 ℃/minute; (ii) maintaining the crystallizable glass at the nucleation temperature for a period of time from about 1/4 hours to about 4 hours to produce a nucleated crystallizable glass; (iii) heating the nucleated crystallizable glass to a crystallization temperature (Tc) at a rate of about 1 ℃ per minute to about 10 ℃ per minute; (iv) maintaining the nucleated crystallizable glass at the crystallization temperature for a time period of from about 1/4 hours to about 4 hours to produce a glass-ceramic as described herein; and (v) cooling the formed glass-ceramic to room temperature. In the preceding embodiments, the term "ceramized" or "ceramized" may be used to denote the general designation of steps (iii), (iv) and optionally (v). In some embodiments, the nucleation temperature may be about 700 ℃ and the crystallization temperature may be about 800 ℃. In some embodiments, the higher the nucleation temperature, the more β -spodumene ss is produced as the secondary crystalline phase.

In addition to the precursor glass composition, the temperature-time profile of the heat treatment step heated to and maintained at the crystallization temperature is carefully selected to produce one or more of the following desired properties: the ratio of the crystalline phases, the one or more primary crystalline phases and/or the one or more secondary crystalline phases to the residual glass of the glass-ceramic, the set of crystalline phases of the one or more primary crystalline phases and/or the one or more secondary crystalline phases to the residual glass, and the grain size or grain size distribution between the one or more primary crystalline phases and/or the one or more secondary crystalline phases, which in turn may affect the final integrity, quality, color, and/or opacity of the resulting formed glass-ceramic.

The resulting glass-ceramic may be provided as a sheet and then may be reshaped into a curved surface or sheet of uniform thickness by pressing, blowing, bending, sagging, vacuum forming, or otherwise. The reshaping may be performed before the heat treatment, or the shaping step may be performed as a heat treatment so that the shaping treatment and the heat treatment are performed substantially simultaneously.

In other embodiments, the precursor glass composition used to form the glass-ceramic may be tailored, for example, to enable chemical strengthening of the glass-ceramic using one or more ion exchange techniques. In these embodiments, one or more surfaces of such glass-ceramics may be imparted with a compressive stress layer by passing the surface or surfaces through one or more ion exchange baths having a particular composition and temperature for a particular period of time. The layer of compressive stress may comprise one or more mean surface Compressive Stresses (CS) and/or one or more depths of layer.

The precursor glasses and glass-ceramics described herein may be generally described as lithium-containing aluminosilicate glasses or glass-ceramics, and include SiO in their base composition₂、Al₂O₃And Li₂And O. Except for SiO₂、Al₂O₃And Li₂In addition to O, the glasses and glass-ceramics practiced herein may also contain an alkali salt (e.g., Na)₂O、K₂O、Rb₂O or Cs₂O) and P₂O₅And ZrO₂And many other components described below. In some embodiments, the precursor glass (before ceramming) and/or the glass-ceramic (after ceramming) may have the following composition, in weight percent on an oxide basis:

SiO₂：55-80％；

Al₂O₃：2-20％；

Li₂O：5-20％；

B₂O₃：0-10％；

Na₂O：0-5％；

ZnO：0-10％；

P₂O₅: 0.5-6%; and

ZrO₂：0.2-15％。

in some embodiments, the precursor glass and/or glass-ceramic has a composition, in weight percent on an oxide basis, that further comprises the following optional additional components:

K₂O：0-4％；

MgO：0-8％；

TiO₂：0-5％；

CeO₂: 0 to 0.4 percent; and

SnO₂：0.05-0.5％。

after the above-described heat treatment of the precursor glass, the resulting glass-ceramic has one or more crystalline phases and has a residual glass phase. In some embodiments, the glass-ceramic contains the following exemplary crystalline phases: lithium silicate salts (including lithium disilicate salts), petalite, beta-spodumene solid solutions, beta-quartz solid solutions, and any combination thereof. In some embodiments, a mixture of lithium disilicate, petalite, and β -quartz solid solution crystalline phases may be present. In other embodiments, a mixture of lithium disilicate and petalite crystalline phases may be present. In other embodiments, a mixture of lithium disilicate and β -spodumene solid solution crystalline phases may be present. In other embodiments, a mixture of lithium disilicate, β -spodumene solid solution, and β -quartz solid solution crystalline phases may be present. In some embodiments, the lithium disilicate is the crystalline phase having the highest weight percentage. In some embodiments, petalite is the crystalline phase with the highest weight percentage. In some embodiments, β -spodumene ss is the crystalline phase having the highest weight percent. In some embodiments, the β -quartz ss is the crystalline phase with the highest weight percentage. In some embodiments, the residual glass content of the glass-ceramic is: about 5 to about 30 wt%, about 5 to about 25 wt%, about 5 to about 20 wt%, about 5 to about 15 wt% about 5 to about 10 wt%, about 10 to about 30 wt%, about 10 to about 25 wt%, about 10 to about 20 wt%, about 10 to about 15 wt%, about 15 to about 30 wt%, about 15 to about 25 wt%, about 15 to about 20 wt%, about 20 to about 30 wt%, about 20 to about 25 wt%, about 25 to about 30 wt%, and all ranges and subranges therebetween. In some embodiments, the residual glass content may be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 weight percent. In some embodiments, the inner region may have the following% by weight of crystals: more than 20 wt% to 100 wt%, more than 20 wt% to 90 wt%, more than 20 wt% to 80 wt%, more than 20 wt% to 70 wt%, 30 wt% to 100 wt%, 30 wt% to 90 wt%, 30 wt% to 80 wt%, 30 wt% to 70 wt%, 40 wt% to 100 wt%, 40 wt% to 90 wt%, 40 wt% to 80 wt%, 40 wt% to 70 wt%, 50 wt% to 100 wt%, 50 wt% to 90 wt%, 50 wt% to 80 wt%, 50 wt% to 70 wt%, and all ranges and subranges therebetween. In some embodiments, the inner region can have a crystalline weight% greater than 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or 90 weight%. The weight% was determined based on X-ray diffraction (XRD) using rietveld analysis.

Final product

The glass-ceramic articles disclosed herein can be integrated into another article, such as an article (or display article) having a display screen (e.g., consumer electronics, including mobile phones, tablets, computers, navigation systems, and wearable devices (e.g., watches), etc.), a construction article, a transportation article (e.g., vehicles, trains, aircraft, nautical equipment, etc., such as for use as interior display coverings, windows, or windshields), an electrical article, or any article requiring partial transparency, scratch resistance, abrasion resistance, or a combination thereof. An exemplary article incorporating any of the glass-ceramic articles disclosed herein is shown in fig. 1A and 1B. Specifically, FIGS. 1A and 1B show a consumer electronic device 100 comprising: a housing 102 having a front surface 104, a back surface 106, and side surfaces 108; electronic components (not shown) at least partially located or entirely within the housing and including at least a controller, a memory, and a display 110 located at or adjacent to the front surface of the housing; and a cover substrate 112 positioned at or above the front surface of the housing so that it is positioned over the display. In some embodiments, at least one of the cover substrate 112 or a portion of the housing 102 can comprise any strengthened glass-ceramic article as disclosed herein.

Examples

Various embodiments are further illustrated by the following examples. In the examples, the examples are referred to as "substrates" prior to being strengthened. After strengthening, the embodiments are referred to as "articles" or "glass-ceramic articles".

The examples are based on glass-ceramic substrates prepared in the following manner. Approximate composition is 73.47 wt% SiO₂7.51% by weight of Al₂O₃2.14% by weight of P₂O₅11.10 wt.% Li₂O, 1.63 wt% Na₂O, 3.55 wt% ZrO₂0.22% by weight of SnO₂The precursor glass of (a) is subjected to the following ceramization scheme: heated to 560 ℃ and held at this temperature for 4 hours, then heated to 720 ℃ and held at this temperature for 1 hour. The resulting glass-ceramic was 14 wt% residual glass, 46 wt% lithium disilicate crystalline phase, 39 wt% petalite crystalline phase, and about 1 wt% secondary crystalline phase. The substrate thickness tested herein was 800 microns.

Example 1

A glass-ceramic article is formed from the lithium-based glass-ceramic substrate mentioned above by a two-step ion exchange process.

The first IOX bath was 100 wt.% KNO₃And 0.5 wt% NaNO was added to the bath₂Dosage to improve bath chemistry. IOX was continued at 460 ℃ for 8 hours. After the first IOX, have: 0.1824% weight gain, 435MPa Compressive Stress (CS), depth of layer (DOL) of 8.1 microns for K (depth of inflection), 25.60MPa maximum Central Tension (CT). FIG. 2 is an image of TM and TE guided-mode spectral fringes after a first IOX process.

The substrate was then exposed to a second IOX bath, which was 90 wt% KNO₃And 10% by weight NaNO₃And contains (of the bath) 0.5% by weight of NaNO₂And (4) dosage. The second IOX was at 430 ℃ for 8 hours. Comprising: 0.3463% weight gain, 339MPa CS, DOL of 9.4 microns for K, 39.75MPa maximum Center Tension (CT). FIG. 3 is an image of the resulting TM and TE guided mode spectral fringes of the glass-ceramic article. In fig. 3, there is a blurring of streaks due to the sodium-rich layer formed after IOX. This sodium-rich layer has a lower refractive index than the substrate, resulting in reduced optical coupling. In this example, although the presence of the sodium-rich layer may make it difficult to measure the streak, the streak is detectable as shown in fig. 3.

Example 2

The glass-ceramic article is formed from the lithium-based glass-ceramic substrate mentioned above by a two-step ion exchange treatment in which lithium is present during the IOX process.

The first IOX bath was 100 wt.% KNO₃To which 0.02 wt% (of bath) of LiNO was added₃Dosage and 0.5 wt% NaNO₂And (4) dosage. The first IOX was at 460 ℃ for 8 hours. Has 0.1219% weight gain and a CT of 17.36 MPa. FIG. 4 is an image of TM and TE guided-mode spectral fringes after the first IOX process.

The substrate was then exposed to a second IOX bath, which was 90 wt% KNO₃And 10% by weight NaNO₃To which 0.02 wt% (of bath) of LiNO was added₃Dosage and 0.5 wt% NaNO₂And (4) dosage. The second IOX was at 430 ℃ for 8 hours. Has 0.3587% weight gain and a CT of 45.78 MPa. FIG. 5 is an image of the resulting TM and TE guided mode spectral fringes of the glass-ceramic article. There are two stripes which enable proper process control for bath composition, bath temperature and ion exchange treatment duration. In this example, a small amount of LiNO was contained in the ion exchange bath (particularly the second bath)₃The sodium rich layer is prevented/eliminated, which results in especially a clearer and curled (crisp) stripe after the second step, reduced variability compared to example 1 and better process control over bath composition, bath temperature and ion exchange treatment duration is achieved.

Example 3

The glass-ceramic article is formed from the lithium-based glass-ceramic substrate mentioned above by a two-step ion exchange treatment in which lithium is present during the IOX process.

The first IOX bath was 100 wt.% KNO₃To which 0.02 wt% (of bath) of LiNO was added₃Dosage and 0.5 wt% NaNO₂And (4) dosage. The first IOX was at 460 ℃ for 8 hours. Has a CT of 15.97 MPa. FIG. 6 is an image of TM and TE guided-mode spectral fringes after the first IOX process. Fig. 7 is a graph of the stress distribution (stress (MPa) versus position (microns)) obtained after the first IOX treatment for half the substrate thickness. In fig. 7, the presence of a spike is noted.

The substrate was then exposed to a second IOX bath, which was 90 wt% KNO₃And 10% by weight NaNO₃To which 0.02 wt% (of bath) of LiNO was added₃Dosage and 0.5 wt% NaNO₂And (4) dosage. The second IOX was at 460 ℃ for 10 hours. Has a CS of 303MPa, a potassium DOL (depth of inflection) of 11.3 microns, and a CT of 44.08 MPa. FIG. 8 is an image of the resulting TM and TE guided mode spectral fringes of the glass-ceramic article. Fig. 9 is a graph of the resulting stress distribution (stress (MPa) versus position (microns)) after the first IOX treatment for half the substrate thickness. Small amplitude vibrations at a depth of about 350 microns are an artifact of the measurement. It can be observed that the measured DOC (about 150 microns, 0.1875 × t) where the stress in the sample was zero remained approximately the same between the first and second ion exchange treatments. The CS of the inflection point where the peak of the distribution and the tail of the distribution meet was approximately 85MPa, and was greatly increased relative to the CS at the inflection point after the first ion exchange treatment (see fig. 7).

Here, the time, temperature and bath dose used achieve that a spike is formed after the first IOX, after which a spike is maintained in the second IOX and a tail of the stress is formed. Under these conditions, there were a minimum of 2 streaks in each step, achieving adequate process control for bath composition, bath temperature and ion exchange treatment duration.

Example 4

The glass-ceramic article is formed from the lithium-based glass-ceramic substrate mentioned above by a two-step ion exchange treatment in which lithium is present during the IOX process.

The first IOX bath was 100 wt.% KNO₃To which 0.15 wt% (of bath) of LiNO was added₃Dose, 0.5% by weight of NaNO₂Dosage, and 0.2 wt% TSP (trisodium phosphate) dosage. The first IOX was at 460 ℃ for 8 hours. Has a CT of 12.32 MPa. FIG. 10 is an image of TM and TE guided-mode spectral fringes after the first IOX process.

The substrate was then exposed to a second IOX bath, which was 90 wt% KNO₃And 10% by weight NaNO₃To which 0.15% by weight (of bath) is addedLiNO of₃Dose, 0.5% by weight of NaNO₂Dosage, and TSP dosage of 0.2 wt%. The second IOX was at 460 ℃ for 10 hours. Has a CS of 276MPa, a DOL of 11.2 microns, and a CT of 42.36 MPa. FIG. 11 is an image of the TM and TE guided mode spectral fringes of the resulting glass-ceramic article.

Here, 0.15% by weight of LiNO was used₃The end of life of the IOX canister is approximated based on the level of commercially tolerated poisoning, followed by cleaning and starting a new fresh canister or using additional added chemicals to reduce and precipitate the amount of Li. One way to precipitate lithium is to use trisodium phosphate (TSP) added to the tank. In this example (relative to example 3) there is a reduction in surface stress, but the process still has clear striations after the second step allowing for measurement and process control after the second step. Using the appropriate time, temperature and bath dose achieves that a spike is formed after the first IOX, after which a spike is maintained in the second IOX and a tail of the stress is formed. Under these conditions, there were a minimum of 2 streaks in each step, achieving adequate process control for bath composition, bath temperature and ion exchange treatment duration.

Example 5

A series of glass-ceramic articles are formed from the above-mentioned lithium-based glass-ceramic substrates by a two-step ion exchange treatment in which lithium is present during the IOX process. The substrate is exposed to: a first IOX bath of (100-x) wt.% KNO₃And x weight% LiNO₃460 ℃ for 8 hours; and a second IOX bath of 90 wt.% KNO₃+ (10-x) weight% NaNO₃+ x% by weight LiNO₃And 430 ℃ for 8 hours.

This example illustrates the dose level versus CT for each of the first and second IOX baths. CT was measured for different "x" values and figure 12 provides the results. With this process, the poisoning amount of the first IOX appears to be very small for the overall CT contribution of the final article, even at the reduced second step temperature of 430 ℃. The stress distribution changes faster with the Li dose in the second IOX. Most of the CT changes are due to the level of lithium poisoning in the second IOX. In a preferred embodiment, the lithium content of each IOX bath is up to 0.2 wt% Li in order to maintain CT values >30 MPa.

For example, the second IOX bath comprises: 90% by weight KNO₃9.3% by weight of NaNO₃And 0.7% by weight of LiNO₃To which 0.5 wt% of NaNO was added₂Dosage (based on bath). The bath temperature was 460 ℃. For this purpose, 1.2% by weight of TSP (of the bath) was added to the bath to precipitate LiNO₃. Reaction (I) represents this chemical case:

100% theoretical conversion will achieve 1.2 wt% TSP such that LiNO in the bath₃And completely precipitating. In practice, about 0.16 wt.% LiNO was still present in the molten salt bath 24 hours after TSP addition₃(0.54% by weight of LiNO precipitated₃). Without intending to be bound by theory, this is because complete reaction takes more than 24 hours to complete and the reaction equilibrium generally retains some lithium in the molten state. Overall, the addition of TSP can maintain the lithium nitrate concentration of the bath to less than 0.05 wt%.

In summary, embodiments of the two-step IOX treatment disclosed herein (which begin with the formation of large spikes in the first IOX and include the presence of a second IOX at a sodium and lithium "poisoning" dose) result in stable bath chemistry and reproducible surface structure. The net result is that the process is controllable, which is expected to result in an article with high impact resistance for drop testing.

Example 6

Forming a series of glass-ceramic articles from the above-mentioned lithium-based glass-ceramic substrate by various processes, including: dual IOX, single IOX (comparative), and no IOX (comparative). Based on the determination of the color stability after the washing treatment according to the measurements of the CIELAB color coordinate system, it was shown that: variability of L parameter, as shown in fig. 13; variability of a parameters, as shown in figure 14; and b variability of the parameters, as shown in fig. 15. In the drawings, "0" refers to a measurement before any cleaning process; "1" refers to the measurement after the first wash/rinse cycle (15 minutes wash and 15 minutes rinse) of 30 minutes; "2" refers to the measurement after the second wash/rinse cycle (15 minutes wash and 15 minutes rinse) of 30 minutes; "3" refers to the measurement after the third wash/rinse cycle (15 minutes wash and 15 minutes rinse) of 30 minutes. The rinse cycle (15 minutes) included a semi-clean (Semiclean) KG in DI water, pH approximately 11, in an ultrasonic bath at 55 ℃. The rinse cycle (15 minutes) included DI water in an ultrasonic bath at 40kHz at 55 ℃. Mean measurements are recorded in figures 13-15 and are based on the 95% confidence interval (95% CI) of the mean.

Bis iox (diox): the first IOX bath was 100 wt.% KNO₃To which 0.02 wt% (of bath) of LiNO was added₃And 0.5% by weight of NaNO₂Dose, 460 ℃ for 8 hours; and the second IOX bath is 90 wt.% KNO₃+ 10% by weight of NaNO₃To which 0.02 wt% (of bath) of LiNO was added₃And 0.5% by weight of NaNO₂Dose, 460 ℃ for 10 hours.

Single iox (siox): 100% by weight NaNO₃At 470 ℃ for 4.5 hours.

No IOX: without exposure to any IOX bath.

For the K-spiked DIOX samples, the color parameters a, b, and L after multiple water wash cycles were more stable than sio or no IOX (test 3).

Similar wash/rinse experiments were performed at pH ranges from about 2 to about 12. The trends of the color parameters, b and L after multiple water wash cycles at different pH are consistent with figures 13-15 at pH of about 11.

Thus, in practice, depending on the chemicals used to perform the cleaning, the cleaning solution may be acidic, alkaline, or neutral, or non-aqueous based, and it is expected that the color of the articles herein will remain stable in the presence of such cleaning solutions.

While the foregoing is directed to various embodiments, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.