Glass with high elastic modulus

Abstract

A glass includes, in terms of mole percent (mol%) of constituents on an oxide basis, at least 18 mol% and no more than 42 mol% silica, at least 18 mol% and no more than 40 mol% alumina, at least 5 mol% alkali metal oxides, at least 2 mol% quicklime, and at least 0.1 mol% and no more than 30 mol% magnesia. A sum of the quicklime and magnesia is at least 26 mol% and no more than 40 mol%.

Description

GLASS WITH HIGH ELASTIC MODULUSCross-reference to Related Applications

[0001] This application claims the benefit of priority of U.S. Application Serial No. 63 / 575,880, filed on April 08, 2024, the content of which is relied upon and incorporated herein by reference in its entirety.BACKGROUND

[0002] Aspects of the present disclosure relate to glass, as may be used as housings or covers for electronic devices or otherwise used.

[0003] Glass, such as sheets of glass, may provide a protective covering for displays of electronic devices, such as cellular phones and laptop computers. The glass may be formed as sheets by a fusion forming process or by so-called float method. The glass may then be cut to shape and integrated in electronic componentry. Further such glass may be naturally strong and may be strengthened, such as by ion-exchange chemical tempering for example. However, constituents to make such glass may be quite rare, possibly requiring resourceintensive mining to procure. Further, such mining may be harmful to the environment.

[0004] A need exists for glasses that may serve as protective covers or in applications possibly benefiting from glass high stiffness, but made with constituents that may be gathered in a fairly sustainable manner.SUMMARY

[0005] Glass of the present disclosure includes fairly common constituents, such as quicklime (CaO), alumina (AI2O3), and silica (Si2O). The glass may further include soda (Na20), magnesia (MgO), and other constituents. The constituents are combined in new and surprising ways, such as including more quicklime than silica for example and as further explained below, whereby the glass surprisingly has a modulus of elasticity exceeding 90 GPa, often exceeding 100 GPa, 110 GPa, and even exceeding 115 GPa. By contrast, “sodalime silicate,” glass of roughly 70 wt% silica with 15 wt% soda, 10 wt% quicklime, and 5 wt% small amounts of other compounds such as alumina, potash (K2O), and magnesia (MgO), has an elastic modulus less than 75 GPa, such as about 70 or 72 GPa. Increased stiffness of the presently disclosed glass provides unique advantages in terms of coating performance and scratch resistance for glass made of prevalent ingredients facilitating use ofthe glass as a protective cover or other applications, such as windows, containers, housings, paneling, and laboratory equipment.

[0006] Additional features and advantages are set forth in the detailed description that follows, and in part will be readily apparent to those skilled in the art from the description or recognized by practicing the technology as described in the written description and claims hereof, 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 understand the nature and character of the claims.BRIEF DESCRIPTION OF THE FIGURE

[0007] The accompanying figure is included to provide a further understanding and is incorporated in and constitutes a part of this specification. The drawing of the figure illustrates one or more aspects of the present disclosure, and together with the detailed description explains principles and operations of the various aspects. As such, the disclosure will become more fully understood from the following detailed description, taken in conjunction with the accompanying figure, in which:

[0008] FIG. 1 is a front view of a gob-pressed glass article according to an aspect of the present disclosure.DETAILED DESCRIPTION

[0009] Before turning to the following detailed description and figure, which illustrate aspects of the present disclosure in detail, it should be understood that the present inventive technology is not limited to the details or methodology set forth in the detailed description or illustrated in the figure. For example, as will be understood by those of ordinary skill in the art, features and attributes associated with an aspect shown in the figure or described in the text relating to an aspect may be applied to another aspect described elsewhere in the text.

[0010] Applicants discovered new glass with useful properties, yet generally made with fairly common constituents. More specifically, the constituents include relatively large amounts of quicklime, alumina, and silica, fairly common materials, and may further include soda, another fairly common material. According to an aspect, the glass may be single-phase,where the glass is amorphous, as opposed to glass ceramic, and the glass has the same physical and chemical properties throughout, having characteristics of an isotropic, homogenous material. Accordingly, aspects of the present disclosure relate to glass, methods of making and using the glass, articles comprising glass, and methods of making and using the articles, where concentrations of constituent components in oxide form (e.g., quicklime, silica, alumina, soda and the like) are specified in mole percent (mol%) on an oxide basis, unless otherwise specified (e.g., when specified by weight percent). It should be noted, beyond the above ingredients, the glass may include other alkali metal oxides, such as potash and perhaps lithia (Li2O). and the glass may include alkaline earth oxides beyond quicklime, such as magnesia; and / or may include zirconia (ZrCh) among other constituents.

[0011] Despite common prevalence of many, most, or even all constituents of the glass, at least some glasses of the present disclosure have remarkably high moduli of elasticity, such as exceeding 90 GPa, often exceeding 100 GPa, 110 GPa, and even exceeding 115 GPa. Elastic modulus (also called Young’s modulus, as in Table 2 below) may be measured by Brillouin spectroscopy (Table 1), resonant ultrasound spectroscopy (Table 2), or simply tensile test, and corresponds with slope of stress (tensile load over cross-sectional area) versus strain (change in length per unit length) over an elastic region of the glass (e.g., approximately until failure for brittle materials such as glass herein) at standard conditions, such as roughly 20° C, 40% relative humidity, sea level atmospheric pressure, etc.Applicants believe new glass made primarily of prevalent ingredients with such high elastic moduli are significant and surprising. Such high-modulus glass advances the art by opening the door for new combinations of materials, such as the glass strengthened by or paired with a coating (e.g., hard coating, anti -reflective coating, anti -glare coating, antimicrobial coating) having a comparable elastic modulus (e.g., within 20 GPa thereof; within 10 GPa thereof; less than that of the glass), and thus overcoming challenges with coatings, such as delamination or interfacial strain caused by elastic modulus mismatch. Further, Applicants believe the glasses disclosed herein have comparable advantages in hardness and scratchresistance, such as when compared to soda-lime silicate.

[0012] According to an aspect, the glass may be translucent and / or transparent, such as having an average transmittance of at least 10% for light in a wavelength range from 380 nm to 750 nm through a pathlength (e.g., thickness) of a linear dimension (e.g., 0.6 mm, 0.8 mm, 1.0 mm, 1.4 mm, 2 mm), such as at least 40%, at least 50%, at least 60%, at least 70%, atleast 80%, and / or even over 90%. Transmittance in the visible spectrum may be measured with a Lambda 950 UV / Vis / NIR Spectrophotometer manufactured by PerkinElmer Inc. (Waltham, Massachusetts USA). The Lambda 950 apparatus may be fitted with a 150 mm integrating sphere. Data may then be collected using an open beam baseline and a Spectralon® reference reflectance disk. For total transmittance, the sample may be fixed at the integrating sphere entry point. The term “average transmittance,” as used herein with respect to the visible spectrum, refers to the average of total transmittance measurements made within a given wavelength range with each whole numbered wavelengths weighted equally. As used herein, the “average transmittance” with respect to the visible spectrum is reported over the wavelength range from 380 nm to 750 nm (inclusive of endpoints). Unless otherwise specified, the average transmittance is indicated for light pathlength (e.g., article thickness) of 0.6 mm through glass of the same composition.

[0013] For “silicate glasses,” silica may typically be the primary or greatest constituent of the glass in mol%, and / or is typically the primary glass former constituent. But for at least some glasses disclosed herein alumina is the primary glass former; and at least some glasses disclosed herein comprise comparable amounts of silica and alumina, as further explained herein, such as within 20 mol% of one another, within 15 mol%, within 10 mol%. In even some glass disclosed herein, alumina is the single greatest constituent of the glass in mol%. The alumina may contribute to the particularly high elastic moduli discovered for glasses disclosed herein.

[0014] According to an aspect of the present disclosure, the glass comprises at least some silica and / or at least some alumina, such as at least 10 mol% of either or both, such as at least 15 mol% thereof, such as at least 18 mol% thereof, such as at least 20 mol% thereof.According to an aspect of the present disclosure, the glass comprises at least 25 mol% of at least one of silica or alumina. Too much silica, such as over 50 mol%, over 45 mol%, or over 42% according to some aspects of the present disclosure, may decrease the elastic modulus or produce a material that is not a single-phase glass when combined with other constituents as disclosed here. Similarly too much alumina, such as over 50 mol%, over 45 mol%, or over 42% according to some aspects of the present disclosure, may produce a material that is not a single-phase glass when combined with other constituents as disclosed here.

[0015] According to an aspect, when alumina is increased, silica is decreased, and vice versa such that the total amount of alumina plus silica is between 41 mol% and 61 mol%,such as between 45 mol% and 55 mol%, which may be viewed as a surprisingly low amount of such network forming constituents by those of skill in the art. According to an aspect, alumina of the glass is in a range of 18 mol% to 40 mol% when combined with silica in a similar range of 18 mol% to 42 mol%. This surprisingly low amount of silica and alumina network formers is then offset by a surprisingly large amount of alkaline earth oxides.

[0016] According to an aspect of the present disclosure, the glass comprises a surprisingly large amount of alkaline earth oxides, such as quicklime and magnesia. The amount is such that those of skill in the art may not expect glasses to form. Applicants find that the large amount of alkaline earth oxides in combination with the above network formers produces glasses of high elastic modulus as disclosed herein. According to an aspect, the glass comprises at least 20 mol% alkaline earth oxides, such as at least 22 mol%, at least 25 mol%, at least 26 mol%, and such amounts may just be in terms of a sum of quicklime and magnesia, such as where the mol% of quicklime plus that of magnesia is at least 26 mol% in sum. According to an aspect, the glass comprises non-zero amounts of both quicklime and magnesia, such as at least 0.08 mol% of each, such as at least 0.1 mol% of each, such as at least 0.08 mol% of magnesia and at least 2 mol% of quicklime in combination with the alumina in the range of 18 mol% to 40 mol% and the silica in the range of 18 mol% to 42 mol%, for example. With that said, too much alkaline earth oxides may undermine glass formation, such as more than 30 mol% of magnesia or more than 40 mol% of quicklime. For example, a sum of magnesia and quicklime may be less than 50 mol%, such as less than 45 mol%, such as less than 40 mol%, such as with at least non-zero amounts of both, such as at least the 0.08 mol% magnesia and at least the 2 mol% quicklime in combination with the silica and alumina as just described. Surprisingly, quicklime may be the greatest oxide constituent of the glass in terms of mol%, as shown in some examples provided herein.

[0017] According to an aspect of the present disclosure, the glass comprises a nonzero amount of alkali metal oxides, such as soda, lithia, and / or potash, such as at least 5 mol%, such as at least 5 mol% soda. The alkali metal oxides may facilitate strengthening of the glass, such as by ion-exchange. Further Applicants believe that at relatively low levels, alkali metal oxides can be swapped for alkaline earth oxides, especially quicklime, without greatly reducing the resulting elastic modulus of the glass. As such a sum of alkali metal oxides plus alkaline earth oxides (such as quicklime + magnesia + soda + lithia in mol%; such as just quicklime + magnesia + soda) may be greater than 35 mol%, such as greater than 40 mol%,such as greater than 41 mol%. Surprisingly, the sum of alkali metal oxides plus alkaline earth oxides may be greater than silica in mol%, may be greater than alumina in mol%, and / or greater than the sum of network formers, such as the sum of silica and alumina. Such a result, forming a glass of high modulus, is surprising because quicklime and magnesia are typically believed to be modifiers, and such glass may have an excess of modifiers, which would presumably increase non-bridging oxides, presumably lowering elastic modulus. But findings disclosed herein show otherwise.

[0018] Soda may be a preferred alkali metal oxide because soda is a fairly common material, as opposed to lithia, and sodium is a relatively small atom, useful during ionexchange chemical tempering where sodium near the surface of an article of such glass may be replaced by larger atoms, such as potassium, to impart compressive stress. However, another contemplated aspect could have high amounts of lithia, such as at least 5 mol%, such as at least 9 mol%, such as at least 10 mol%, at least 11 mol%, and / or no more than 25 mol%. Such glass may benefit from high modulus as well as relatively strong chemical tempering.

[0019] As shown in Tables 1 and 2 below, in addition to the above disclosed constituents, glasses disclosed herein may further comprise phosphorus pentoxide (P2O5), boria (B2O3), yttria (Y 2O3), and zirconia (ZrCh) for example. Further they may include some stannic oxide (SnCF) as a fining agent for example, or other fining agents. For example, the glass may include at least 0.01 mol% phosphorous pentoxide. The glass may optionally comprise boria, such as zero in some glass, at least 1 mol% and / or no more than 26 mol% in other glass as disclosed herein. Boria may increase scratch resistance. The glass may optionally comprise yttria, such as zero in some glass, at least 1 mol% and / or no more than 7 mol% in other glass disclosed herein. Yttria may increase stiffness, but may be a fairly rare material compared to others disclosed herein. The glass may optionally comprise zirconia, such as zero in some glass, at least 1 mol% and / or no more than 5 mol% in other glass disclosed herein.

[0020] Many of the glasses disclosed herein have particularly high strain points, as shown in the examples, such as over 600° C, such as over 625° C, over 650° C, and even over 675° C in some cases. Accordingly, Applicants believe that the glasses may be chemically tempered in unusually hot baths of molten salt, such as in baths at temperatures exceeding 500° C, such as exceeding 525° C, such as exceeding 550° C, to improve the chemical tempering. Applicants find that to effectively use the salt at such temperatures, a combination of nitrogen- and sulfur-based salts may be used, with increasing weightpercentages of sulfur-based salts with higher temperature baths. Further the baths may include potassium- and sodium-containing salts, if the glass includes soda or other alkali metal oxides in amounts as disclosed above. As such, according to an aspect, the glasses may be ion-exchanged to have a surface or peak compressive stress (e.g., at least 50 MPa, at least 100 MPa) and central tension (e.g., at least 10 MPa) in a salt bath comprising a molten mixture of sodium nitrate, sodium sulfate, potassium nitrate, and / or potassium sulfate salts at a temperature exceeding 500° C. In the salt bath, wt% of sodium nitrate may be greater than sodium sulfate, wt% of potassium nitrate may be greater than potassium sulfate, and / or wt% of sodium-containing salts may be greater than potassium -containing salts. Hotter salt baths may increase the depth of compression (e.g., at least 5 pm, at least 10 pm, at least 30 pm), where compressive stress transitions to tensile within an article of the glass, may shorten an amount of time for soaking the glass in such baths, and may increase surface or peak compressive stress compared to chemical tempering in salt baths at temperatures under 400° C and of all nitrate salts for example. Applicants hereby incorporate by reference herein in its entirety U.S. Application No. 63 / 600,790 fded November 20, 2023.

[0021] The following Table 1 provides examples of glass made and found to have properties disclosed herein. The examples are presented in terms of mol% as analyzed. Physical properties of the glass are measured by Brillouin scatter and may include some range of error or tolerance for error, such as + / - 10%. Liquidus is measured by gradient boat and may likewise include some range of error or tolerance for error, such as + / - 5%.TABLE 1:TABLE 1 (continued):

[0022] The following Table 2 provides examples of glass samples made and found to have properties disclosed herein. The examples are provided in terms of mol% as analyzed. The abbreviation RUS is for resonant ultrasound spectroscopy, BBV is for beam bending viscosity, and PPV is for parallel plate viscosity, and measurement methods may include some range of error or tolerance for error, such as + / - 10%; see also ASTM C829-81 and ASTM Cl 35 IM. Liquidus is measured by gradient boat and may likewise include some range of error or tolerance for error, such as + / - 5%; see also ASTM C829-81. Some common properties herein are measured by different techniques (e.g., Brillouin scatter and resonant ultrasound spectroscopy), so unless otherwise specified when claimed, quantities refer to those measurable by the techniques of Table 2, such as with a reasonable degree of error tolerance as disclosed or known in the art.TABLE 2:TABLE 2 (continued)TABLE 2 (continued)

[0023] According to an aspect and as shown with the examples, the glass may have a density of at least 2.5 g / cm3, such as at least 2.6 g / cm3, such as at least 2.612 g / cm3, and / or no more than 3.1 g / cm3, such as no more than 3.011 g / cm3. The density may be for example between 2.6 g / cm3and 3 g / cm3.

[0024] According to an aspect and as shown with the examples, the glass may have a refractive index at 589.3 nm using Brillouin scatter of at least 1.5 (unitless), such as at least 1.55, such as at least 1.567, and / or no more than 1.7, such as no more than 1.65, such as no more than 1.63, such as no more than 1.628. The refractive index may be for example between 1.55 and 1.65.

[0025] According to an aspect and as shown with the examples, the glass may have a Young’s modulus (aka elastic modulus), as measured by Brillouin scatter or by resonant ultrasound spectroscopy, of at least 80 GPa, such as at least 90 GPa, such as at least 95 GPa, such as at least 96.5 GPa, and / or no more than 140 GPa, such as no more than 125 GPa, such as no more than 115 GPa, such as no more than 110.7 GPa. The Young’s modulus may befor example between 90 GPa and 140 GPa, such as between 100 GPa and 130 GPa, such as between 110 GPa and 125 GPa.

[0026] According to an aspect and as shown with the examples, the glass may have a shear modulus, as measured by Brillouin scatter or by resonant ultrasound spectroscopy, of at least 30 GPa, such as at least 35 GPa, such as at least 38 GPa, such as at least 38.2 GPa, and / or no more that 55 GPa, such as no more than 50 GPa, such as no more than 45 GPa, such as no more than 43.6 GPa. The shear modulus may be for example between 35 GPa and 50 GPa.

[0027] According to an aspect and as shown with the examples, the glass may have a Poisson’s ratio, as measured by Brillouin scatter or by resonant ultrasound spectroscopy, of at least 0.25 (unitless), such as 0.26, such as 0.262 and / or no more than 0.29, such as no more than 0.28, such as no more than 0.273. The Poisson’s ratio may be for example between 0.25 and 0.29.

[0028] Viscosity of the glass may be measured according to ASTM C829-81. “Softening point” may refer to the temperature at which viscosity of the glass is 1 x IO7 6poise. The softening point may be measured according to parallel plate viscosity method, which measures viscosity of glass from 107to 109poise as a function of temperature, similar to ASTM Cl 35 IM. “Annealing point” or “anneal point” may refer to the temperature at which viscosity of the glass is 1 x 1013 18poise. “Strain point” may refer to the temperature at which viscosity of the glass is 1 x IO14 68poise. “Liquidus viscosity” may refer to the viscosity of the glass at the onset of devitrification, when crystallization first occurs, or at the liquidus temperature as determined with gradient furnace method according to ASTM C829-81. As such, “liquidus temperature” may refer to the temperature at which the glass composition begins to devitrify as determined with the gradient furnace method according to ASTM C829-81.

[0029] According to an aspect and as shown with the examples, the glass may have a liquidus temperature, as measured by gradient boat, of at least at least 1150° C, such as at least 1200° C and / or no more than 1600° C, such as no more than 1500° C. The liquidus temperature may be for example between 1200° C and 1500° C.

[0030] According to an aspect and as shown with the examples, the glass may have a strain point, as measured by beam bending viscosity, of at least at least 450° C, such as at least 460° C, such as at least 500° C, and / or no more than 800° C, such as no more than 750° C, such as no more than 700° C. The strain point may be for example between 450° C and 750° C.

[0031] According to an aspect and as shown with the examples, the glass may have an anneal point, as measured by beam bending viscosity, of at least at least 470° C, such as at least 490° C, such as at least 491° C, such as at least 520° C, and / or no more than 820° C, such as no more than 770° C, such as no more than 750° C, such as no more than 739° C. The anneal point may be for example between 490° C and 750° C.

[0032] According to an aspect and as shown with the examples, the glass may have a softening point, as measured by parallel plate viscosity, of at least at least 470° C, such as at least 600° C, such as at least 620° C, such as at least 628° C, and / or no more than 950° C, such as no more than 910° C, such as no more than 904° C. The softening point may be for example between 620° C and 910° C.

[0033] According to an aspect and as shown with the examples, the glass may have HTV A (unitless) ranging from -8.4, such as -8.423, to 1.5, such as 1.478; HTV B ranging from 140° C, such as 148.4° C, to 14500° C, such as 14371.6° C; and HTV To ranging from -550° C, such as -499.7° C, to 1250° C, such as 1124.1° C.

[0034] According to an aspect and as shown with the examples, the glass may have a liquidus viscosity less than 1000 poise, such as less than 500 poise, such as less than 200 poise, such as no more than 168.5 poise, and / or at least 1 poise, such at least 5 poise, such as at least 7.4 poise. Those of skill in the art may find glass with such low liquidus viscosity challenging to form into articles, such as by fusion or float methods. According to an aspect, methods of making an article with glass disclosed herein comprise gob-pressing the glass, such as dropping a gob of molten glass into a mold and quickly pressing the molten glass to a desired shape, where a gob is a discrete- and relatively-small-volume of molten glass, such as less than 0.5 L for example. “Pre-shaping” the gob prior to positioning the gob in the mold, such as elongating the gob, may allow for thinner articles with thicker portions further from a center of the mold, for example. U.S. Patent Application No. 63 / 525,060 filed July 5, 2023 is hereby incorporated by reference herein in its entirety. Additionally, pressing the glass more than once may improve dimensional control of the pressing, reducing need for finishing.

[0035] FIG. 1 includes an image representative of a glass article 110 (e.g., parts blank) formed by gob pressing glass as disclosed herein. Such an article may be cut into glass parts, and finished, such as by computer numerical control grinding and polishing, to form an article that may be used in an electronic device, such as a housing or cover as disclosed above, or elsewhere. Similarly, glass disclosed herein may be formed into other articles, such as flat or curved sheets, containers, housings, panels, fibers, substrates (e.g., for memory disk, circuit, packaging), windows, covers, etc.

[0036] Construction and arrangements of the compositions, assemblies, and structures, as shown in the various aspects, are illustrative only. Although only a few examples of the aspects have been described in detail in this disclosure, modifications are possible (e.g., variations in sizes, dimensions, structures, shapes, and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations) without materially departing from the novel teachings and advantages of the subject matter described herein. For example, while being translucent and / or transparent as disclosed above, the glass and corresponding articles may be colored, and each of U.S. Application No. 63 / 537,466 filed September 8, 2023 and International Application No. PCT / US23 / 82806 filed December 7, 2023 is incorporated by reference herein in its entirety. The order or sequence of any process, logical algorithm, or method steps may be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes and omissions may also be made in the design, operating conditions and arrangement of the various aspects without departing from the scope of the present inventive technology.

Claims

WHAT IS CLAIMED IS:1 . A glass, comprising in terms of mole percent (mol%) of constituents on an oxide basis: at least 18 mol% and no more than 42 mol% silica; at least 18 mol% and no more than 40 mol% alumina; at least 5 mol% alkali metal oxides; alkaline earth oxides such that the glass comprises: at least 2 mol% quicklime; and at least 0. 1 mol% and no more than 30 mol% magnesia; and wherein a sum of the alkaline earth oxides is at least 26 mol% and no more than 40 mol%.

2. The glass of claim 1, wherein a sum of the quicklime and the magnesia is greater than the silica in terms of mol%.

3. The glass of claim 2, wherein the quicklime is greater than the magnesia in terms of mol%.

4. The glass of any one of claims 1 to 3, wherein the alkali metal oxides comprise soda such that the glass comprises at least 5 mol% soda.

5. The glass of claim 4, wherein the alkali metal oxides further comprise a nonzero amount of lithia.

6. The glass of claim 1, wherein the alkali metal oxides comprise a non-zero amount of lithia.

7. The glass of claim 1, wherein the glass is a single-phase glass.

8. The glass of claim 1, wherein the glass has an average transmittance of at least 10% for light in a wavelength range from 380 nm to 750 nm through a thickness of 0.6 mm.

9. A glass, comprising: constituents comprising soda, quicklime, and silica, wherein a sum of the soda, the quicklime, and the silica is greater than half of the glass in terms of mole percent (mol%) of constituents on an oxide basis, and wherein the silica is less than 40 mol% of the glass; wherein the glass is a single-phase glass; wherein the glass has an average transmittance of at least 60% for light in a wavelength range from 380 nm to 750 nm through a thickness of 0.6 mm; and wherein the glass has a modulus of elasticity greater than 90 GPa.

10. The glass of claim 9, wherein the glass comprises at least 30 mol% alkaline earth oxides, the alkaline earth oxides including the quicklime.

11. The glass of claim 10, wherein the alkaline earth oxides further comprise at least 0. 1 mol% magnesia.

12. The glass of claim 10, wherein the glass comprises a greater mol% of the alkaline earth oxides than the silica.

13. A method of making a glass article, comprising gob-pressing the glass of any of the above claims to at least partially form the article.

14. A method of making a glass article, comprising tempering the glass of any of the above claims in a salt bath at a temperature greater than 500° C.

15. The method of claim 14, wherein the salt bath comprises sodium sulfate and sodium nitrate, with a greater amount of sodium nitrate than sodium sulfate in terms of weight percentage of the salt bath.

16. A method of making a glass article, comprising coating the glass of any of the above claims with a coating having a modulus of elasticity no more than 40 GPa greater than the glass.

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