BACKGROUND

This disclosure relates to glass-based articles exhibiting improved damage resistance, including improved fracture resistance, and more particularly to glass and glass ceramic articles exhibiting a non-zero metal oxide concentration gradient or concentration that varies along a substantial portion of the thickness.

Glass-based articles often experience severe impacts that can introduce large flaws into a surface of such articles. Such flaws can extend to depths of up to about 200 micrometers from the surface. Traditionally, thermally tempered glass has been used to prevent failures caused by the introduction of such flaws into the glass because thermally tempered glass often exhibits large compressive stress (CS) layers (e.g., approximately 21% of the total thickness of the glass), which can prevent the flaws from propagating further into the glass and thus, can prevent failure. An example of a stress profile generated by thermal tempering is shown inFIG. 1. InFIG. 1, the thermally treated glass-based article100includes a first surface101, a thickness t1, and a surface CS110. The thermally treated glass-based article100exhibits a CS that decreases from the first surface101to a depth of compression (DOC)130, as defined herein, at which depth the stress changes from compressive to tensile stress and reaches a maximum central tension (CT)120.

Thermal tempering is currently limited to thick glass-based articles (i.e., glass-based articles having a thickness t1of about 3 millimeters or greater) because, to achieve the thermal strengthening and the desired residual stresses, a sufficient thermal gradient must be formed between the core of such articles and the surface. Such thick articles are undesirable or not practical in many applications such as display (e.g., consumer electronics, including mobile phones, tablets, computers, navigation systems, and the like), architecture (e.g., windows, shower panels, countertops etc.), transportation (e.g., automotive, trains, aircraft, sea craft, etc.), appliance, or any application that requires superior fracture resistance but thin and light-weight articles.

Although chemical strengthening is not limited by the thickness of the glass-based article in the same manner as thermally tempering, known chemically strengthened glass-based articles do not exhibit the stress profile of thermally tempered glass-based articles. An example of a stress profile generated by chemical strengthening (e.g., by an ion exchange process), is shown inFIG. 2. InFIG. 2, the chemically strengthened glass-based article200includes a first surface201, a thickness t2and a surface CS210. The glass-based article200exhibits a CS that decreases from the first surface201to a DOC230, as defined herein, at which depth the stress changes from compressive to tensile stress and reaches a maximum CT220. As shown inFIG. 2, such profiles exhibit a substantially flat CT region or CT region with a constant or near constant tensile stress along at least a portion of the CT region. Often, known chemically strengthened glass-based articles exhibit a lower maximum CT value, as compared to the maximum central value shown inFIG. 1.

Additionally, the ion exchange processes that can be used in chemical strengthening, particularly where a large, heavy atom is exchanged into the glass for a smaller ion can result in undesired increases weight and dimensions in the substrate. These changes can be particularly problematic for glass-based articles with beveled edges or other asymmetric features. In such glass-based articles, the changes in weight and dimensions result in warping. Methods to reduce these undesired shape changes in the final (larger and/or warped) part, post-ion exchange, can involve etching or polishing to preferentially remove material, thereby producing a part with the desired features. These procedures, however, necessarily add more process steps to manufacturing; this is costly and due to increased handling may result in lower yields of final parts. In addition, they will usually incur unwanted reduction of the spike CS in particular, possibly unwanted reduction in the spike thickness.

Accordingly, there is a need for thin glass-based articles that exhibit improved fracture resistance, as well as improved methods of ion exchange processes that reduce undesired changes in the glass-based article.

SUMMARY

A first aspect of the present disclosure pertains to a glass-based article including a first surface and a second surface opposing the first surface defining a thickness (t); a concentration of a metal oxide that is both non-zero and varies along a thickness range from about 0·t to about 0.3·t; and a central tension (CT) region comprising a maximum CT greater than or equal to 71.5/√J(t), wherein, when the glass-based article is fractured, the glass-based article fractures into at least 2 fragments/inch2(fragments per square inch). As used herein, the variation in metal oxide concentration may be referred to herein as a metal oxide concentration gradient. In one or more embodiments, the concentration of the metal oxide is non-zero and varies along the entire thickness. In one or more embodiments, the CT region may include a metal oxide concentration that is both non-zero and varies along a thickness range from about 0·t to about 0.3·t. The glass-based article of one or more embodiments may include a thickness t of about 3 millimeters (mm) or less, 2 mm or less, or about 1 mm or less.

A second aspect of this disclosure pertains to a glass-based article including a first surface and a second surface opposing the first surface defining a thickness (t) of about less than about 3 millimeters, and a stress profile extending along the thickness, wherein all points of the stress profile between a thickness range from about 0·t up to 0.3·t and from greater than 0.7·t, comprise a tangent having an absolute value that is greater than about 0.1 MPa/micrometer, wherein the stress profile comprises a maximum CS, a DOC and a maximum CT greater than or equal to 71.5/√(t), wherein the ratio of maximum CT to maximum CS is in the range from about 0.01 to about 0.2 and wherein the DOC is about 0.1·t or greater.

A third aspect of this disclosure pertains to a glass-based article including a first surface and a second surface opposing the first surface defining a thickness (t); and a concentration of a metal oxide that is both non-zero and varies along a thickness range from about 0·t to about 0.3·t (or from about 0·t to about 0.4·t or from about 0·t to about 0.45·t), a surface compressive stress of greater than about 200 MPa or greater; and a CT region having a maximum CT greater than or equal to 71.5/√(t).

A fourth aspect of this disclosure pertains to a glass-based article comprising: a first surface and a second surface opposing the first surface defining a thickness (t); and a metal oxide that forms a concentration gradient, wherein the concentration of the metal oxide decreases from the first surface to a point between the first surface and the second surface and increases from the point to the second surface, wherein the concentration of the metal oxide at the point is non-zero, and wherein the glass-based article comprises a stored tensile energy of about greater than 0 J/m2to less than 20 J/m2and an elastic modulus of about 70 GPa or greater.

A fifth aspect of this disclosure pertains to a glass-based article comprising: a first surface and a second surface opposing the first surface defining a thickness (t) of about less than about 3 millimeter; and a stress profile extending along the thickness, wherein the stress profile at all points between a thickness range from about 0t up to 0.3 t and from greater than 0.7t, comprise a tangent having an absolute value of greater than about 0.1 MPa/micrometer, wherein the stress profile comprises a maximum CS, a DOC and a maximum CT, wherein the ratio of maximum CT to maximum CS is in the range from about 0.01 to about 0.2 and wherein the DOC is about 0.1·t or greater, and wherein the glass-based article comprises a stored tensile energy of about greater than 0 J/m2to less than 20 J/m2and an elastic modulus of about 70 GPa or greater. In one or more embodiments, the glass-based article includes a non-zero concentration of a metal oxide that continuously varies along the entire thickness. In some instances, the non-zero concentration of a metal oxide that continuously varies along thickness segments of less than about 10 micrometers.

A sixth aspect of this disclosure pertains to a glass-based article including a stress profile including a CS region and a CT region, wherein the CT region is defined by the equation Stress(x)=MaxT−(((CTn·(n+1))/0.5n)·|(x/t)−0.5|n), wherein MaxT is a maximum tension value, CTnis less than or equal to MaxT and provided as a positive value in units of MPa, x is position along the thickness (t) in micrometers, and n is between 1.5 and 5. In some embodiments, the maximum CT value in the range from about 50 MPa to about 250 MPa and the maximum CT value is at a depth in the range from about 0.4t to about 0.6t. In one or more embodiments, from a thickness in the range from about 0·t to about 0.1t, the stress profile comprises a slope in the range from about 20 MPa/micron to about 200 MPa/micron. In one or more embodiments, the stress profile is defined by a plurality of error functions as measured from 0.5t to the surface.

In accordance with one or more embodiments of the glass-based articles described herein, a monovalent ion of the metal oxide generates a stress along the thickness range from about 0·t to about 0.3·t, from about 0·t to about 0.4·t, or from about 0·t to about 0.45·t. The concentration of the metal oxide of one or more embodiments decreases from the first surface to a point between the first surface and the second surface and increases from the point to the second surface.

In one or more embodiments, the concentration of the metal oxide concentration is about 0.05 mol % or greater throughout the thickness. For example, in one or more embodiments, the concentration of the metal oxide at the first surface is about 1.5 times greater than the concentration of the metal oxides at a depth equal to about 0.5·t. In exemplary embodiments, the glass-based article comprises a total concentration of the metal oxide in the range from about 1 mol % to about 15 mol %. In one or more embodiments, examples of the metal oxide include any one or more of Li2O, Na2O, K2O, Rb2O, and Cs2O. In one or more embodiments, the metal oxide has a largest ionic diameter of all of the total metal oxides in the glass-based substrate or article.

In one or more embodiments, the CT region comprises the metal oxide that is both non-zero and varies along a thickness range from about 0·t to about 0.3·t. In one or more embodiments of the glass-based articles described herein, the maximum CT is greater than or equal to 71.5/√(t).

The glass-based article of some embodiments includes a first metal oxide concentration and a second metal oxide concentration. In some embodiments, the first metal oxide concentration is in the range from about 0 mol % to about 15 mol % in a first thickness range from about 0·t to about 0.5·t. In some embodiments, the second metal oxide concentration is in the range from about 0 mol % to about 10 mol % in a second thickness range from about 0 micrometers to about 25 micrometers. The glass-based article may include an optional third metal oxide.

In one or more embodiments, the glass-based articles described herein may exhibit a surface compressive stress (CS) that is greater than the maximum CT. One or more embodiments of the glass-based articles described herein may include a surface CS of about 300 MPa or greater. In some instances, this surface CS is exhibited when the glass-based article has a thickness of about 2 mm or less. In one or more embodiments, the glass-based article exhibits a combination of a surface CS of about 200 MPa or greater and a chemical depth of layer of about 0.4·t or greater. In one or more embodiments, the glass-based article includes a CS extending from the first surface to a DOC, wherein the DOC is about 0.1·t or greater. In some instances, the ratio of maximum CT to surface CS is in the range from about 0.1 to about 0.8.

In one or more embodiments, the glass-based article has an amorphous structure. In some embodiments, the glass-based article may include a crystalline structure.

In one or more embodiments, the glass-based articles described herein may exhibit a transmittance of about 88% or greater over a wavelength in the range from about 380 nm to about 780 nm. In some instances, the glass-based articles described herein may exhibit CIELAB color space coordinates, under a CIE illuminant F02, of L* values of about 88 and greater, a* values in the range from about −3 to about +3, and b* values in the range from about −6 to about +6.

In one or more embodiments, the glass-based articles described herein may include an elastic modulus of about 70 GPa or greater. In some embodiments, the glass-based articles described herein include a liquidus viscosity of less than about 100 kilopoise (kP). In one or more embodiments, the glass-based articles described herein exhibit a fracture toughness (K1C) of about 0.65 MPa·m1/2or greater. In one or more embodiments, the glass-based articles described herein include any one or more of: a composition comprising a combined amount of Al2O3and Na2O of about 15 mol % or less, a composition comprising about 4 mol % or greater Na2O, a composition comprising any one or more of B2O3and ZnO, and a composition substantially free of P2O5. In one or more embodiments, glass-based article comprises a monovalent ion diffusivity of about 450 μm2/hour (square micrometers per hour) or greater at about 460° C. In some embodiments, this monovalent ion diffusivity is exhibited in combination with a DOC greater than about 0.15·t, and a surface CS that is 1.5 times the maximum CT or greater.

In one or more embodiments, the glass-based articles described herein exhibit certain fracture behavior. For example, in one or more embodiments, when the glass-based article is fractured by a single event (i.e., a single impact such as being dropped or being impacted once with an implement), the glass-based article fractures into at least 2 fragments/inch2(fragments per square inch). In some embodiments, when the glass-based article is fractured, the glass-based article fractures into at least 1 fragment/inch2up to 40 fragments/inch2(fragments per square inch).

A seventh aspect of this disclosure pertains to a use of a glass substrate in a strengthened glass-based article. In one or more embodiments, the glass substrate comprises (in mol %): SiO2in an amount in the range from about 68% to about 75%; Al2O3in an amount in the range from about 12% to about 15%; B2O3in an amount in the range from about 0.5% to about 5%; Li2O in an amount in the range from about 2% to about 10%; Na2O in an amount in the range from about 0% to about 6%; MgO in an amount in the range from about 1% to about 4%; ZnO in an amount in the range from about 0% to about 3%; and CaO in an amount in the range from about 0% to about 5%, wherein the glass substrate is ion-exchangeable and is amorphous. In one or more embodiments, the glass substrate exhibits any one or more of: a ratio of Li2O to R2O in the range from about 0.45 to about 1; a difference between a total amount of R2O to the amount of Al2O3in the range from about −5% to about 0%; a difference between a total amount of RxO (in mol %) and the amount of Al2O3in the range from about 0% to about 3%; and a ratio of the amount of MgO (in mol %) to a total amount of RO (in mol %) in the range from about 0% to about 1%, and wherein the glass substrate is substantially free of nucleating agents.

A eighth aspect of this disclosure pertains to a glass substrate comprising a composition including, in mol %, SiO2in an amount in the range from about 68% to about 75%; Al2O3in an amount in the range from about 12% to about 15%; B2O3in an amount in the range from about 0.5% to about 5%; Li2O in an amount in the range from about 2% to about 10%; Na2O in an amount in the range from about 0% to about 6%; MgO in an amount in the range from about 1% to about 4%; ZnO in an amount in the range from about 0% to about 3%; and CaO in an amount in the range from about 0% to about 5%, wherein the glass substrate is ion-exchangeable and is amorphous. In one or more embodiments, the glass substrate exhibits any one or more of: a ratio of Li2O to R2O in the range from about 0.45 to about 1; a difference between a total amount of R2O to the amount of Al2O3in the range from about −5% to about 0%; a difference between a total amount of RxO (in mol %) and the amount of Al2O3in the range from about 0% to about 3%; and a ratio of the amount of MgO (in mol %) to a total amount of RO (in mol %) in the range from about 0% to about 1%. In one or more embodiments, the glass substrate is substantially free of nucleating agents.

An ninth aspect of this disclosure pertains to a glass substrate that includes in mol %, SiO2in an amount in the range from about 68% to about 75%; Al2O3in an amount in the range from about 12% to about 15%; B2O3in an amount in the range from about 0.5% to about 5%; Li2O in an amount in the range from about 2% to about 10%; Na2O in an amount in the range from about 0% to about 6%; MgO in an amount in the range from about 1% to about 4%; ZnO in an amount in the range from about 0% to about 3%; and CaO in an amount in the range from about 0% to about 5%, wherein the glass substrate is amorphous and is strengthened. In one or more embodiments, the Na2O concentration varies in the glass substrate. In one or more embodiments, the glass substrate is substantially free of nucleating agents. In accordance with one or more embodiments, the strengthened glass substrate exhibits any one or more of the following compositional relationships: a ratio of Li2O to R2O in the range from about 0.45 to about 1; a difference between a total amount of R2O to the amount of Al2O3in the range from about −5% to about 0%; a difference between a total amount of RxO (in mol %) and the amount of Al2O3in the range from about 0% to about 3%; and a ratio of the amount of MgO (in mol %) to a total amount of RO (in mol %) in the range from about 0% to about 1%.

A tenth aspect of this disclosure pertains to a device comprising: a housing having front, back, and side surfaces; electrical components that are at least partially inside the housing; a display at or adjacent to the front surface of the housing; and a cover substrate disposed over the display, wherein the cover substrate or housing comprises a glass-based article according the embodiments described herein.

An eleventh aspect of this disclosure pertains to a method of forming a chemically strengthened glass-based article. In one or more embodiments, the method comprises: providing a glass-based substrate comprising a first surface and a second surface opposing the first surface defining a thickness (t), a length dimension, a width, and a weight; and ion exchanging a plurality of alkali ions into the glass-based substrate to form a non-zero alkali metal oxide concentration that varies along at least a substantial portion of the thickness (t), wherein ion exchanging comprises immersing the glass-based substrate in a molten salt bath comprising at least about 90% by weight of a potassium salt (e.g. KNO3), and less than about 10% by weight of a sodium salt (e.g., NaNO3) for less than about 12 hours.

In one or more embodiments, the molten salt bath further comprises a lithium salt (e.g., LiNO3) in an amount of less than about 2% by weight. In some embodiments, the thickness is less than about 2 mm. In one or more embodiments, the thickness is less than about 1 mm. In some embodiments, the thickness is about 0.8 mm. In one or more embodiments, there is a less than 1.6% gain in the weight after ion exchanging compared to before ion exchanging. In some embodiments, there is a less than 0.24% change in the length dimension after ion exchanging compared to before ion exchanging. In one or more embodiments, there is a less than 0.24% change in the width after ion exchanging compared to before ion exchanging. In some embodiments, the glass-based article warps less than 200 μm after ion exchanging compared to the glass substrate before ion exchanging. In one or more embodiments, the potassium salt (e.g., KNO3) is present in an amount of at least 92% by weight. In some embodiments, the potassium salt (e.g. KNO3) is present in an amount of at least 94% by weight. In one or more embodiments, the potassium salt (e.g., KNO3) is present in an amount of about 95% by weight. In some embodiments, the sodium salt (e.g., NaNO3) is present in an amount of less than about 8% by weight. In one or more embodiments, the sodium salt (e.g., NaNO3) is present in an amount of less than about 5% by weight. In some embodiments, the sodium salt (e.g., NaNO3) is present in an amount of about 5% by weight. In one or more embodiments, the potassium salt (e.g., KNO3) is present in an amount ranging from about 90% to about 97% by weight, and the sodium salt (e.g., NaNO3) is present in an amount ranging from about 10% to about 3% by weight. In some embodiments, the glass-based article is ion exchanged for less than about 12 hours. In one or more embodiments, the glass-based article is ion exchanged for less than about 10 hours. In some embodiments, there is a change in the length dimension after ion exchanging compared to before ion exchanging ranging from about 0.2% to about 0.15% by weight. In one or more embodiments, the method further comprises a second ion exchange in a second molten salt bath comprising a potassium salt (e.g., KNO3).

A twelfth aspect of the disclosure pertains to a glass-based article prepared by the methods described herein. In some embodiments, the glass-based article is an ion-exchanged glass-based article comprising: a length dimension; a width dimension; a weight; a first surface and a second surface opposing the first surface defining a thickness (t); a concentration of an ion-exchanged metal oxide that is both non-zero and varies along a thickness range from about 0·t to at least about 0.3·t; and a central tension (CT) region comprising a maximum CT greater than or equal to 71.5/√(t), where the thickness t is given in mm. In one or more embodiments, when the thickness (t) of the glass-based article is 0.8 mm: (1) there is less than a 1.6% gain in the weight of the glass-based article resulting from the ion-exchanged metal oxide compared to the weight of the glass-based substrate prior to ion exchange, (2) there is less than a 0.24% change in the length dimension of the ion-exchanged glass-based article compared to the length dimension of the glass-based substrate prior to ion exchange, and (3) there is less than a 0.24% change in the width dimension of the glass-based article compared to the width dimension of the glass-based substrate prior to ion exchange.

In some embodiments, the there is less than a 1.4% gain in weight of the glass-based article resulting from the ion-exchanged metal oxide compared to the weight of the glass-based substrate prior to ion exchanging. In one or more embodiments, there is less than a 0.15% change in the length dimension of the ion-exchanged glass-based article compared to the length dimension of the glass-based substrate prior to ion exchange. In some embodiments, there is less than a 0.15% change in the width dimension of the glass-based article compared to the width dimension of the glass-based substrate prior to ion exchange. In one or more embodiments, the article further comprises a surface compressive stress (CS) of about 300 MPa or greater. In some embodiments, the surface CS is about 400 MPa or greater. In one or more embodiments, t comprises about 1 millimeter or less.

A thirteenth aspect of the disclosure pertains to a device comprising a housing having front, back, and side surfaces; electrical components that are at least partially inside the housing; a display at or adjacent to the front surface of the housing; and a cover substrate disposed over the display, wherein the cover substrate or housing comprises the glass-based article as described in any of the above embodiments.

In embodiment (1) of the disclosure, a method of forming a chemically strengthened glass-based article is provided. The method comprises: providing a glass-based substrate comprising a first surface and a second surface opposing the first surface defining a thickness (t), a length dimension, a width, and a weight; and ion exchanging a plurality of alkali ions into the glass-based substrate to form a non-zero alkali metal oxide concentration that varies along at least a substantial portion of the thickness (t). The ion exchanging comprises immersing the glass-based substrate in a molten salt bath comprising at least about 90% by weight of a potassium salt, and less than about 10% by weight of a sodium salt for less than about 12 hours.

In embodiment (2) of the disclosure, the method of embodiment (1) is provided, wherein the molten salt bath further comprises a lithium salt in an amount of less than about 2% by weight.

In embodiment (3) of the disclosure, the method of embodiment (1) or (2) is provided, wherein the thickness is less than about 2 mm.

In embodiment (4) of the disclosure, the method of any of embodiments (1) to (3) is provided, wherein the thickness is less than about 1 mm.

In embodiment (5) of the disclosure, the method of any of embodiments (1) to (4) is provided, wherein the thickness is about 0.8 mm.

In embodiment (6) of the disclosure, the method of any of embodiments (1) to (4) is provided, wherein the potassium salt is KNO3, the sodium salt is NaNO3, and the lithium salt is LiNO3the there is a less than 1.6% gain in weight after ion exchanging compared to before ion exchanging.

In embodiment (7) of the disclosure, the method of any of embodiments (1) to (6) is provided, wherein there is a less than 0.24% change in the length dimension after ion exchanging compared to before ion exchanging.

In embodiment (8) of the disclosure, the method of any of embodiments (1) to (7) is provided, wherein there is a less than 0.24% change in the width after ion exchanging compared to before ion exchanging.

In embodiment (9) of the disclosure, the method of any of embodiments (1) to (8) is provided, wherein the glass-based article warps less than 200 μm after ion exchanging compared to before ion exchanging.

In embodiment (10) of the disclosure, the method of any of embodiments (1) to (9) is provided, wherein the potassium salt is present in an amount of at least 92% by weight.

In embodiment (11) of the disclosure, the method of any of embodiments (1) to (10) is provided, wherein the potassium salt is present in an amount of at least 94% by weight.

In embodiment (12) of the disclosure, the method of any of embodiments (1) to (11) is provided, wherein the potassium salt is present in an amount of about 95% by weight.

In embodiment (13) of the disclosure, the method of any of embodiments (1) to (12) is provided, wherein the sodium salt is present in an amount of less than about 8% by weight.

In embodiment (14) of the disclosure, the method of any of embodiments (1) to (13) is provided, wherein the sodium salt is present in an amount of less than about 6% by weight.

In embodiment (15) of the disclosure, the method of any of embodiments (1) to (14) is provided, wherein the sodium salt is present in an amount of about 5% by weight.

In embodiment (16) of the disclosure, the method of any of embodiments (1) to (15) is provided, wherein the potassium salt is present in an amount ranging from about 90 to about 97% by weight and the sodium salt is present in an amount ranging from about 10 to about 3% by weight.

In embodiment (17) of the disclosure, the method of any of embodiments (1) to (16) is provided, wherein the glass-based article is ion exchanged for less than about 12 hours.

In embodiment (18) of the disclosure, the method of any of embodiments (1) to (17) is provided, wherein the glass-based article is ion exchanged for less than about 10 hours.

In embodiment (19) of the disclosure, the method of any of embodiments (1) to (18) is provided, wherein there is a change in the length dimension after ion exchanging compared to before ion exchanging ranging from about 0.2 to about 0.15% by weight.

In embodiment (20) of the disclosure, the method of any of embodiments (1) to (19) is provided, further comprising a second ion exchange in a second molten salt bath comprising a potassium salt.

In embodiment (21) of the disclosure, a glass-based article prepared by the method of any of embodiments (1) to (20) is provided.

In embodiment (22) of the disclosure, an ion-exchanged glass-based article is provided. The ion-exchanged glass-based article comprises: a length dimension; a width dimension; a weight; a first surface and a second surface opposing the first surface defining a thickness (t); a concentration of an ion-exchanged metal oxide that is both non-zero and varies along a thickness range from about 0·t to at least about 0.3·t; and a central tension (CT) region comprising a maximum CT greater than or equal to 71.5/√(t), where the thickness t is given in mm. The thickness (t) of the glass-based article is 0.8 mm. There is less than 1.6% gain in weight of the glass-based article resulting from the ion-exchanged metal oxide compared to the weight of the glass-based substrate prior to ion exchange, there is less than 0.24% change in the length dimension of the ion-exchanged glass-based article compared to the length dimension of the glass-based substrate prior to ion exchange, and there is less than 0.24% change in the width dimension of the glass-based article compared to the width dimension of the glass-based substrate prior to ion exchange.

In embodiment (23) of the disclosure, the glass-based article of embodiment (22) is provided, wherein there is less than a 1.4% gain in weight of the glass-based article resulting from the ion-exchanged metal oxide compared to the weight of the glass-based substrate prior to ion exchanging.

In embodiment (24) of the disclosure, the glass-based article of embodiment (22) or (23) is provided, wherein there is less than a 0.15% change in the length dimension of the ion-exchanged glass-based article compared to the length dimension of the glass-based substrate prior to ion exchange.

In embodiment (25) of the disclosure, the glass-based article of any of embodiments (22) to (24) is provided, wherein there is a less than 0.15% change in the width dimension of the glass-based article compared to the width dimension of the glass-based substrate prior to ion exchange.

In embodiment (26) of the disclosure, the glass-based article of any of embodiments (22) to (25) is provided, further comprising a surface compressive stress (CS) of about 300 MPa or greater.

In embodiment (27) of the disclosure, the glass-based article of any of embodiments (22) to (26) is provided, wherein the surface CS is about 400 MPa or greater.

In embodiment (28) of the disclosure, the glass-based article of any of embodiments (22) to (27) is provided, wherein t comprises about 1 millimeter or less.

In embodiment (29) of the disclosure, a device is provided comprising: a housing having front, back, and side surfaces; electrical components that are at least partially inside the housing; a display at or adjacent to the front surface of the housing; and a cover substrate disposed over the display, wherein the cover substrate or housing comprises the glass-based article of any of embodiments (22) to (28).

In aspect (1) of the disclosure, a method of forming a chemically strengthened glass-based article is provided. The method comprises: ion exchanging a plurality of alkali ions into the glass-based substrate to form a glass-based article with a non-zero alkali metal oxide concentration that varies along at least a substantial portion of the thickness (t) of the glass-based article. The glass-based substrate comprises a glass-based substrate comprising a first surface and a second surface opposing the first surface defining a thickness (t), a length dimension, a width, and a weight. The ion exchanging comprises immersing the glass-based substrate in a molten salt bath comprising a weight ratio of a potassium salt to a sodium salt greater than the lesser of (a) 2.5:1 and (b) a molar ratio of (Li2O+K2O):Na2O in the glass-based substrate, for a time in the range of 50% to 130% of the ion exchange time that produces a peak central tension (CT) with the same molten salt bath composition and temperature.

In aspect (2) of the disclosure, the method of aspect (1) is provided, wherein the molten salt bath further comprises a lithium salt in an amount of less than about 2% by weight.

In aspect (3) of the disclosure, the method of aspect (1) or (2) is provided, wherein the thickness is less than about 2 mm.

In aspect (4) of the disclosure, the method of any of aspects (1) to (3) is provided, wherein the thickness is less than about 1 mm.

In aspect (5) of the disclosure, the method of any of aspects (1) to (4) is provided, wherein the thickness is about 0.8 mm.

In aspect (6) of the disclosure, the method of any of aspects (1) to (5) is provided, wherein the potassium salt is KNO3, the sodium salt is NaNO3, and the lithium salt is LiNO3, and there is a less than 1.6% gain in weight after ion exchanging compared to before ion exchanging.

In aspect (7) of the disclosure, the method of any of aspects (1) to (6) is provided, wherein there is a less than 0.24% change in the length dimension after ion exchanging compared to before ion exchanging.

In aspect (8) of the disclosure, the method of any of aspects (1) to (7) is provided, wherein there is a less than 0.24% change in the width after ion exchanging compared to before ion exchanging.

In aspect (9) of the disclosure, the method of any of aspects (1) to (8) is provided, wherein the glass-based article warps less than 200 μm after ion exchanging compared to the glass substrate before ion exchanging.

In aspect (10) of the disclosure, the method of any of aspects (1) to (9) is provided, wherein the potassium salt is present in an amount of at least 92% by weight.

In aspect (11) of the disclosure, the method of any of aspects (1) to (10) is provided, wherein the potassium salt is present in an amount of at least 94% by weight.

In aspect (12) of the disclosure, the method of any of aspects (1) to (11) is provided, wherein the potassium salt is present in an amount of about 95% by weight.

In aspect (13) of the disclosure, the method of any of aspects (1) to (12) is provided, wherein the sodium salt is present in an amount of less than about 8% by weight.

In aspect (14) of the disclosure, the method of any of aspects (1) to (13) is provided, wherein the sodium salt is present in an amount of less than about 6% by weight.

In aspect (15) of the disclosure, the method of any of aspects (1) to (14) is provided, wherein the sodium salt is present in an amount of about 5% by weight.

In aspect (16) of the disclosure, the method of any of aspects (1) to (15) is provided, wherein the potassium salt is present in an amount of at least about 90% and the sodium salt is present in an amount of about 10% by weight or less.

In aspect (17) of the disclosure, the method of any of aspects (1) to (16) is provided, wherein the potassium salt is present in an amount ranging from about 90% to about 97% by weight and the sodium salt is present in an amount ranging from about 10% to about 3% by weight.

In aspect (18) of the disclosure, the method of any of aspects (1) to (17) is provided, wherein the glass-based article is ion exchanged for a time in the range of 70% to 130% of the ion exchange time that produces a peak central tension (CT) with the same molten salt bath composition and temperature.

In aspect (19) of the disclosure, the method of any of aspects (1) to (18) the glass-based article is ion exchanged for less than about 12 hours.

In aspect (20) of the disclosure, the method of any of aspects (1) to (19) is provided, wherein the glass-based article is ion exchanged for less than about 10 hours.

In aspect (21) of the disclosure, the method of any of aspects (1) to (20) is provided, wherein there is a change in the length dimension after ion exchanging compared to before ion exchanging ranging from about 0.1% to about 0.2%.

In aspect (22) of the disclosure, the method of any of aspects (1) to (21) is provided, further comprising a second ion exchange in a second molten salt bath comprising a potassium salt.

In aspect (23) of the disclosure, the method of any of aspects (1) to (22) is provided, wherein the glass substrate has a 2.5D or 3D shape.

In aspect (24) of the disclosure, the method of any of aspects (1) to (23) is provided, wherein the ion exchanging produces an increase in Na2O concentration at a center point of the glass substrate of less than 1.3 mol %.

In aspect (25) of the disclosure, the method of any of aspects (1) to (24) is provided, wherein the glass-based article comprises a compressive stress spike, and a spike depth of layer (DOLspike), wherein DOLspike/t is in the range from about 0.006 to about 0.014.

In aspect (26) of the disclosure, the method of aspect (25) is provided, wherein DOLspike/t is in the range from about 0.008 to about 0.012.

In aspect (27) of the disclosure, the method of any of aspects (1) to (26) is provided, wherein the glass-based article comprises lithium.

In aspect (28) of the disclosure, the method of any of aspects (1) to (27) is provided, wherein the Na2O molar concentration at the center point of the glass-based article is less than 45% of the total alkali metal oxide molar concentration of the glass-based article at the center point.

In aspect (29) of the disclosure, the method of any of aspects (1) to (28) is provided, wherein the Na2O concentration at the center point of the glass-based article is less than 4.5 mol %.

In aspect (30) of the disclosure, the method of any of aspects (1) to (29) is provided, wherein the glass-based article has a maximum central tension greater than or equal to 71.5/√(t), where the thickness t is given in mm.

In aspect (31) of the disclosure, a glass-based article prepared by the method of any of aspects (1) to (30) is provided.

In aspect (32) of the disclosure, a glass-based article is provided. The glass-based article comprises: a first surface and a second surface opposing the first surface defining a thickness (t); a concentration of an ion-exchanged metal oxide that is both non-zero and varies along a thickness range from about 0·t to at least about 0.3·t; Li2O; and Na2O. The content of Na2O at a center point of the glass-based article is less than about 4.5 mol %.

In aspect (33) of the disclosure, the glass-based article of aspect (32) is provided, wherein the content of Na2O at the center point of the glass-based article is less than about 4.0 mol %.

In aspect (34) of the disclosure, the glass-based article of aspect (32) or (33) is provided, wherein the content of Na2O at a center point of the glass-based article is less than about 3.0 mol %.

In aspect (35) of the disclosure, a glass-based article is provided. The glass-based article comprises: a first surface and a second surface opposing the first surface defining a thickness (t); a concentration of an ion-exchanged metal oxide that is both non-zero and varies along a thickness range from about 0·t to at least about 0.3·t; and Na2O. The molar concentration of Na2O at a center point of the glass-based article is less than about 45% of the total alkali metal oxide molar concentration of the glass-based article at the center point.

In aspect (36) of the disclosure, the glass-based article of aspect (35) is provided, wherein the molar concentration of Na2O at the center point of the glass-based article is less than about 40% of the total alkali metal oxide molar concentration of the glass-based article at the center point.

In aspect (37) of the disclosure, a glass-based article is provided. The glass-based article comprises: a first surface and a second surface opposing the first surface defining a thickness (t); a concentration of an ion-exchanged metal oxide that is both non-zero and varies along a thickness range from about 0·t to at least about 0.3·t; and a compressive stress spike depth of layer (DOLspike). The DOLspike/t is in the range from about 0.006 to about 0.014.

In aspect (38) of the disclosure, the glass-based article of aspect (37) is provided, wherein DOLspike/t is in the range from about 0.008 to about 0.012.

In aspect (39) of the disclosure, the glass-based article of aspect (37) or (38) is provided, wherein DOLspike/t is in the range from about 0.009 to about 0.011.

In aspect (40) of the disclosure, the glass-based article of any of aspects (37) to (39) is provided, wherein DOLspike/t is about 0.01.

In aspect (41) of the disclosure, the glass-based article of any of aspects (32) to (40) is provided, wherein t is in the range from about 0.03 mm to about 1.3 mm.

In aspect (42) of the disclosure, the glass-based article of any of aspects (32) to (41) is provided, wherein t is about 0.8 mm.

In aspect (43) of the disclosure, the glass-based article of any of aspects (32) to (42) is provided, further comprising a surface compressive stress (CS) of about 300 MPa or greater.

In aspect (44) of the disclosure, the glass-based article of any of aspects (32) to (43) is provided, wherein the surface CS is about 400 MPa or greater.

In aspect (45) of the disclosure, the glass-based article of any of aspects (32) to (44) is provided, wherein the glass-based article has a 2.5D or 3D shape.

In aspect (46) of the disclosure, the glass-based article of any of aspects (32) to (45) is provided, wherein a Na2O concentration is a minimum at a center of the glass-based article.

In aspect (47) of the disclosure, the glass-based article of any of aspects (32) to (46) is provided, further comprising a warp of less than about 200 μm.

In aspect (48) of the disclosure, a strengthened glass-based article is provided. The strengthened glass-based article comprises: an inner region under a central tension CT; at least one compressive stress layer under a compressive stress CS, the compressive stress layer extending from a surface of the glass-based article to a depth of compression DOC, wherein DOC≥0.1·t when t<0.5 mm and DOC≥50 μm when t≥0.5 mm, and being adjacent to the inner region. The strengthened glass-based article has at least a 60% survivability rate when subjected to an inverted ball drop test with a 4.2 g stainless steel ball having a diameter of 10 mm from a height of 100 cm onto a 30 grit sandpaper positioned above the surface of the glass so there is a 100 μm air gap between the sandpaper and the surface of the glass, wherein the survivability rate is based on testing at least 5 samples.

In aspect (49) of the disclosure, the glass-based article of aspect (48) is provided, wherein the strengthened glass-based article has at least a 60% survivability rate when subjected to the inverted ball drop test from a height of 150 cm.

In aspect (50) of the disclosure a device is provided. The device comprises: a housing having front, back, and side surfaces; electrical components that are at least partially inside the housing; a display at or adjacent to the front surface of the housing; and a cover substrate disposed over the display, wherein the cover substrate or housing comprises the glass-based article of any one of aspects (31) to (49).

Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments as described herein, including the detailed description which follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description and the following detailed description are merely exemplary, and are intended to provide an overview or framework to understanding the nature and character of the claims. The accompanying drawings are included to provide a further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment(s), and together with the description serve to explain principles and operation of the various embodiments.

