TW202210439A - Chemical ion exchange glass - Google Patents

Abstract

The present invention describes a chemical strengthening process such as a double ion exchange process of a glass material. The glass composition comprises of SiO₂ , Al₂ O₃ , B₂ O₃ , Li₂ O, Na₂ O, ZrO₂ , ZnO, P₂ O₅ , and one or more refining agents. The invention describes a compressive stress-depth of layer (CS-DOL) profile and its analysis by considering areas of the curves and the angles formed by tangents of the curves. The invention also discloses stress areas from the CS-DOL profile and their impact on the chemical strengthening process. The CS-DOL profile allows to determine inequalities from stress areas and the angles of the curves. The inequalities help in predicting the strength of the cover glass and adjusting the processing parameters such as time and temperature during the chemical strengthening process.

Description

chemical ion exchange glass

The present invention relates to a chemical ion exchange glass. More specifically, the present invention focuses on deriving strengthening expressions for chemical ion exchange glasses by considering compressive stress (CS)-depth of layer (DOL) distributions. Even more specifically, the present invention describes a method for defining the reaction parameters of a dual ion exchange process by considering the area under the curve of the CS-DOL distribution and the angle formed by the tangent to the curve.

In recent years, glass substrates have been widely used as cover glass for electronic devices such as mobile phones, entertainment devices, tablet computers, notebook computers, digital cameras, and wearable devices. Cover glass is used to enhance the protection of the display screen of electronic devices. In addition to providing strength to the electronic device, the cover glass used on the backside of the electronic device also needs to provide enhanced electromagnetic radio signal transmission. As tempered glass becomes more widely used, cover glass is chemically or heat-treated to resist breakage when subjected to high tensile strengths. Typically, glass compositions are subjected to high surface compressive stress to increase the strength of the glass. In the case of chemical strengthening processes, the dual ion exchange process is a known process for producing glass substrates with high strength and durability, especially for thin glasses where physical strengthening is very difficult or even impossible.

The chemical strengthening of double ion exchange glasses is generally defined by the compressive stress (CS)-depth of layer (DOL) distribution. The CS-DOL distribution contains two curves with different slopes. The curve of the CS-DOL distribution was taken as a measurement parameter for estimating the performance of the double ion exchange glass. Various methods and models have been derived by using the CS-DOL distribution to determine the chemical strengthening process of glass. It is necessary to use the best calculation parameters to meet the customer's requirements for chemically strengthened glass materials.

In view of the foregoing, the present invention derives inequalities by using the CS-DOL distribution to define the chemical strengthening process of glass materials. Object of the present invention

Some objects of the present invention are described herein. An object of the present invention is to provide glass compositions that undergo a dual ion exchange process. Another object of the present invention is to use alkali metal aluminosilicate glass materials for cover glass.

Another object of the present invention is to increase the strength of the cover glass by chemically strengthening the double ion exchange process.

Another object of the present invention is to provide a compressive stress-depth of layer (CS-DOL) profile for chemically strengthened glass. Another objective of the present invention is to evaluate the CS-DOL distribution by considering the area under the curve and the angle formed by the tangent of the curve to define the reaction parameters of the double ion exchange process.

Another object of the present invention is to use the inequalities obtained from the CS-DOL distribution to define process parameters for dual ion exchange glass materials. Another object of the present invention is to determine the stress area, treatment time and temperature of the double ion exchange glass material according to the CS-DOL distribution.

Another object of the present invention is to provide a cover glass with higher performance strength, better service life, higher crack resistance and higher sharp impact strength.

Other objects and advantages of the present invention will become apparent from the following description, which is not intended to limit the scope of the invention.

In one embodiment, the present invention describes a glass composition. The glass composition includes one or more chemical components, such as SiO ₂ , Al ₂ O ₃ , Li ₂ O, B ₂ O ₃ and Na ₂ O. It may also contain other chemical components such as ZrO ₂ , MgO, CaO, P ₂ O ₅ , ZnO, K ₂ O, TiO ₂ and the like. In addition, it may also contain refining agents such as SnO ₂ , Fe ₂ O ₃ , CeO ₂ , chlorides, sulfates, and the like.

In one embodiment, the present invention describes the optimum molar % of the various components of the glass composition. The glass composition comprises about 50 mol % to about 75 mol % SiO ₂ , about 5 mol % to about 25 mol % Al ₂ O ₃ , about 0 mol % to about 10 mol % B _{2 O3} , about 0 mol% to about 15 mol% Na2O, about ₅ mol% to about 17 mol% _Li2O , about 0 mol% to about ₂ mol% K2O , about 0 mol % to about 7 mol % MgO, about 0 mol % to about 3 mol % CaO, about 0 mol % to about 7 mol % P ₂ O ₅ , about 0 mol % % to about 7 mol % ZnO and about 0 mol % to about 7 mol % ZrO ₂ . The glass composition also includes one or more refining agents, such as, about 0 mol% to about 2.5 mol% _SnO2 , about 0 mol% to about 2.5 mol% _Fe2O3 , about ₀ mol% To about ₂ mol% CeO2, and other refining agents such as chlorides and sulfates. Additionally, the glass composition further includes about 0 mol% to about 2 mol% _TiO2 .

In one embodiment, the cover glass can have high strength by chemical strengthening through multiple ion exchanges. The present invention defines cover glass strengthened by a double ion exchange process.

In one embodiment, the dual ion exchange process comprises a first ion exchange step on the outer surface area of the glass material followed by a second ion exchange step. In one embodiment, the ion exchange process is based on the size of the ions. When larger ions in the glass material are exchanged for smaller ions, the larger ions fill the surface area previously occupied by the smaller ions, creating a compressive stress on the inner surface of the glass material that corresponds to an increase in the strength of the glass material.

In one embodiment, the salt bath contains 5-95 wt% NaNO3 and 5-95 wt _{% KNO3} during the first ion exchange process. _The salt bath contains 0-50 wt% NaNO3 and 50-100 wt% _KNO3 during the second ion exchange process. _The amounts of NaNO3 and _KNO3 used in the salt bath are presented for exemplary purposes only and should not be construed as limiting the scope of the invention.

In one embodiment, the first ion exchange process can be performed at a temperature greater than 300°C for a duration of at least 0.25 hours. In one embodiment, the second ion exchange process may be performed at a temperature greater than 300°C for a duration of 0.1 hour to 6.5 hours.

In one embodiment, the glass is under a compressive stress (CS) in the range of 60 MPa to 650 MPa and a layer depth in the range of 45 μm to 210 μm due to the first ion exchange process. Furthermore, due to the second ion exchange process, the glass is under compressive stress in the range of 130 MPa to 1400 MPa and a layer depth of less than 60 μm.

In one embodiment, the compressive stress-depth-of-layer (CS-DOL) distribution for the dual ion exchange process comprises two curves. The present invention calculates the area under the curve and the angle formed by the tangent to the curve. The CS-DOL distribution describes the stress area and various reaction parameters, such as the time and temperature of the double ion exchange process. The CS-DOL distribution helps to understand and adjust the chemical strengthening process parameters of glass materials.

In one embodiment, the dual ion exchange glass yields enhanced in-service durability, high crack resistance, high retention strength after damage, and high sharp impact strength.

In one embodiment, double ion exchange glass is used as the cover glass. Cover glass can be used as a substrate for touch panel displays and as the back cover of these displays, such as Liquid Crystal Displays (LCD), Field Emission Displays (FED), Plasma Displays (PD), Electroluminescent Displays (ELD), Organic Light Emitting Displays (OLEDs) Level-on-body (OLED) displays, micro LEDs, or the like. Double ion exchange glass can also be used as the substrate of solar cell cover glass, disk substrate and window glass. In addition, cover glass can be used to protect display screens, such as touch displays of electronic devices such as mobile phones, smart phones, tablet computers, wearable devices, and digital cameras. Cover glass can be used on the backside of electronic devices to provide not only strength, but also enhanced electromagnetic radio signal transmission. However, the application of cover glass is not limited to the aforementioned information, and can also be used as a substrate for signage, building interiors and exteriors, interior displays and windshields of automobiles, windows associated with various modes of transportation, and the like.

These and other aspects, advantages and salient features of the present invention will become apparent from the following detailed description.

claim of priority

This application claims priority from Indian Provisional Application Serial No. 202021032695 filed on July 30, 2020, the entire contents of which are incorporated herein by reference.

In the following description, like reference numerals refer to like or corresponding parts throughout the several views shown in the drawings. It should also be understood that unless stated otherwise, terms such as "top," "bottom," "outward," "inward," and the like are words of convenience and should not be construed as terms of limitation. Furthermore, whenever a group is described as comprising at least one of a group of elements and combinations thereof, it will be understood that the group can comprise, consist essentially of, any number of those elements, alone or in combination with each other or consist of it. Similarly, whenever a group is described as consisting of at least one of a group of elements, or a combination thereof, it will be understood that the group can consist of any number of those elements, alone or in combination with each other. Unless otherwise stated, when a range of values is recited, it includes the upper and lower limits of the range and any range therebetween. As used herein, the indefinite article "a/an" and the corresponding definite article "the" mean "at least one" or "one or more" unless stated otherwise. ". It should also be understood that the various features disclosed in the specification and accompanying drawings can be used in any and all combinations.

As used herein, the term "glass article (glass articles)" is used in its broadest sense to include any object made entirely or partially of glass. All compositions are expressed in mole percent (mol %) unless otherwise stated. All temperatures are expressed in degrees Celsius (°C) unless otherwise stated.

It should be noted that the terms "substantially" and "about" may be used herein to denote the inherent degree of uncertainty attributable to any quantitative comparison, value, measurement or other representation. These terms are also used herein to denote the extent to which a quantitative representation may differ from a stated reference without resulting in a change in the basic functionality of the subject matter discussed.

Reference is made to the drawings described in this disclosure, it should be understood that the illustrations are for the purpose of describing particular embodiments and are not intended to limit the scope of the disclosure or the appended claims thereto. The figures are not necessarily to scale and certain features of the figures and certain views of the figures may be shown exaggerated in scale or schematically for the sake of clarity and conciseness.

Unless otherwise specified, as used herein, the terms "depth of ion exchange layer" and "DOL" refer to the depth of the compressive layer and are expressed in micrometers (μm), where 1 μm = 0.001 mm, and thickness “t” is used herein Expressed in millimeters, where 1 mm=1000 μm.

As described herein, compressive stress (CS) and central tension (CT) are expressed in megapascals (MPa). According to convention commonly used in the art, compressive stress is expressed as a negative value (<0) and tensile stress is expressed as a positive value (>0). However, throughout this specification, compressive stress is expressed as a positive or absolute value, ie, CS=|CS|, as stated herein.

The present invention describes a dual ion exchange glass. Double ion exchange glass was used as cover glass. The present invention further details various compositions of cover glass. _The glass composition includes one or more chemical components, such as _SiO2 , _Al2O3 , _Li2O , _B2O3 , and _{Na2O .} It may also contain other chemical components such as ZrO ₂ , MgO, CaO, P ₂ O ₅ , ZnO, K ₂ O, TiO ₂ and the like. In addition, it may also contain refining agents such as SnO ₂ , Fe ₂ O ₃ , CeO ₂ , chlorides, sulfates, and the like.

The present invention describes increasing the strength of alkali metal aluminosilicate glasses by multiple ion exchange processes, such as double ion exchange processes. The dual ion exchange process comprises a first ion exchange step on the outer surface area of the glass material followed by a second ion exchange step. In one embodiment, the ion exchange process is based on the size of the ions. When larger ions in the glass material are exchanged for smaller ions, the larger ions fill the surface area previously occupied by the smaller ions, creating a compressive stress on the inner surface of the glass material that corresponds to an increase in the strength of the glass material.

The present invention describes compressive stress-depth-of-layer (CS-DOL) distributions for various glass compositions and their analysis. The present invention calculates the area under the curve and the angle formed by the tangent to the curve. The present invention also describes the stress area and various reaction parameters, such as the time and temperature of the double ion exchange process. CS-DOL distribution helps to understand and adjust chemical strengthening process parameters to obtain suitable glass materials.

1 is a graph illustrating a compressive stress-depth-of-layer (CS-DOL) profile 100 corresponding to a double ion exchange strengthening process of an alkali metal aluminosilicate glass according to an exemplary embodiment of the present invention. In one embodiment, the chemical strengthening process is performed by double ion exchange treatment in salt baths of different concentrations. The double ion exchange treatment involves the steps of treating the alkali metal aluminosilicate glass in a salt bath, replacing at least a portion of the smaller alkali metal cations with larger alkali metal cations, and determining the surface layer of the alkali metal aluminosilicate glass. A first depth corresponding to compressive stress (Dstep1), and further displacement of at least a portion of the displaced alkali metal cation (previously added larger cation) with another larger alkali metal cation, resulting in a depth corresponding to less than the first (Dstep1) The higher compressive stress at the second depth (Dstep2). Replacing smaller alkali metal cations with larger alkali metal cations increases the compressive stress in the compressive depth layer and increases the damage resistance of the glass surface, thereby enhancing the chemical strengthening of the alkali metal aluminosilicate glass.

As shown in Figure 1, CS-DOL distributions were obtained due to double ion exchange treatment of alkali metal aluminosilicate glasses in salt baths of different concentrations. Graph 100 includes an X-axis representing layer depth (x) and a Y-axis representing corresponding compressive stress (Cx). Graph 100 shows compressive stress Cx as a function of layer depth (x). The CS-DOL distribution shown in Figure 1 is inherently nonlinear. The CS _- DOL distribution of Figure ₁₀₀ includes curve ai and curve a2 with varying slopes. Curve a1 represents the compressive stress obtained due to the _first ion exchange of the alkali metal aluminosilicate glass. Specifically, curve a1 defines the _first step of ion exchange for alkali metal aluminosilicate glasses. Curve a2 represents the compressive stress obtained due to the _second step of ion exchange of the alkali metal aluminosilicate glass. Specifically, curve a2 defines the _second step of ion exchange for alkali metal aluminosilicate glass. The curves a ₁ and a ₂ intersect at the intersection. The compressive stress at this intersection is determined at the depth of Dstep2. Specifically, the compressive stress at the intersection is denoted herein as CS _k . Furthermore, the maximum compressive stress is obtained when the layer depth is zero, and is denoted herein as CS _m . At the depth of compression, the stress spans from positive (compressive) to negative (tensile) stress, and thus has a value of zero. The compression depth is denoted Dstep1 in this paper.

FIG. 2 is a diagram illustrating a CS-DOL profile 200 showing compressive stress areas formed by a double ion exchange strengthening process of alkali metal aluminosilicate glasses, according to an exemplary embodiment of the present invention. The double ion exchange strengthening process of alkali metal aluminosilicate glasses is defined by curve a ₁ and curve a ₂ in the CS-DOL distribution shown in FIG. 1 . As shown in FIG. 2 , the curve a ₁ is approximated by the first straight line a ₁₁ , and the curve a ₂ is approximated by the second straight line a ₂₂ . The intersection between the _first straight line _a11 and the second straight line _a22 is defined as the inflection point (DOL_TP, _{CS_TP} ) of the curve formed by the adjacent curve a1 and the curve a2. _In addition, the first straight line a11 extends from the inflection point to a point with zero compressive stress and a maximum layer depth defined as (DOL_ZERO, 0). Furthermore, the second straight line a ₂₂ extends from the inflection point to a point with zero layer depth and a maximum compressive stress defined as (0, CS).

Considering FIG. 2, the compressive stress area under the first line a ₁₁ and the second line a ₂₂ for the double ion exchange strengthening process of alkali metal aluminosilicate glass is calculated below.

Let the first compressive stress area A be the first process stress area of the first step of the double ion exchange strengthening process. The CS-DOL profile includes a first area under the first straight line _a11 , which defines the first compressive stress area A of the first ion exchange of the alkali metal aluminosilicate glass. The first compressive stress area A in FIG. 2 is a trapezoidal area with coordinates (0, 0), (0, CS_TP), (DOL_TP, CS_TP) and (DOL_ZERO, 0) as vertices. Calculate the first compressive stress area A by the following expression: A = (CS_TP x DOL_ZERO x 0.5) + (CS_TP x DOL_TP) (1)

In addition, let the second compressive stress area B be the second process stress area of the second step of the double ion exchange strengthening process. The CS-DOL profile includes a second area under the second straight line a ₂₂ that defines the second compressive stress area B of the second step ion exchange of the alkali metal aluminosilicate glass. The second compressive stress area B in FIG. 2 is a trapezoidal area with coordinates (0, 0), (DOL_TP, 0), (DOL_TP, CS_TP) and (0, CS) as vertices. Calculate the second compressive stress area B by the following expression: B = (CS x DOL_TP x 0.5) + (CS_TP x DOL_TP) (2)

Considering expressions (1) and (2) and the above measured parameters, the ratio of the first and second compressive stress areas A and B formed by the first and second chemical strengthening processes is within the range defined below : 0.1 ≦ |(A/B)|^0.5 ≦5.2

In addition, FIG. 2 is helpful for understanding the reaction temperature and time of the chemical strengthening process of the alkali metal aluminosilicate glass. The CS-DOL distribution includes a third region between the line a ₃₃ extending from the point of depth of compression (DOL_TP, 0) to the point of maximum compressive stress (0, CS) and the first line a ₁₁ and the second line a ₂₂ , which define The third compressive stress area C. Let the third compressive stress area C be the area excluding the first and second process stress areas. The third compressive stress area C is defined by the following expression: C = (CS x DOL_ZERO x 0.5) - (CS_TP x DOL_ZERO x 0.5 +CS_TP x DOL_TP + CS x DOL_TP x 0.5) (3)

Furthermore, the CS-DOL distribution includes a fourth area under the first straight line a ₁₁ , and the second straight line a ₂₂ defines a fourth area D of compressive stress. Let the fourth compressive stress area D be the area under the first straight line _a11 and the second straight line _a22 . Specifically, the fourth compressive stress area D is the sum of the first and second process stress areas. The fourth compressive stress area D is defined by the following expression: D = (CS_TP x DOL_ZERO x 0.5 + CS_TP x DOL_TP + CS x DOL_TP x 0.5) (4)

Considering expressions (3) and (4), the ratio of the third and fourth compression areas C and D, which describe the reaction temperature and time of the double ion exchange intensification process, is within the range defined as follows: 0.2 ≦ |(C/D) |^0.5 ≦ 6

The ratio range of the third compressive stress area C to the fourth compressive stress area D is inversely proportional to the reaction temperature and time of the double ion exchange strengthening process of the alkali metal aluminosilicate glass. The shorter the reaction time or the lower the temperature, the higher the ratio of the third compressive stress area C to the fourth compressive stress area D is.

3 is a graph illustrating a CS-DOL profile 300 estimating the timing of the first and second steps of the double ion exchange strengthening process for alkali metal aluminosilicate glasses according to an exemplary embodiment of the present invention. The double ion exchange strengthening process of alkali metal aluminosilicate glasses is defined by curve a ₁ and curve a ₂ in the CS-DOL distribution shown in FIG. 3 . The intersection between the curves a ₁ and a ₂ is defined as the inflection point (DOL_TP, CS_TP) of the curve formed by the adjoining curves a ₁ and a ₂ . As shown in FIG. ₃ , the third straight line a3 extends from the maximum value of CS _on the curve a2 to the point where the curve _a2 is linear. This point is defined as a linear point (DOL_Linear, CS_Linear).

Considering Figure 3, the angle E is substantially the angle formed by the _third straight line a3 at the linear point (DOL_Linear, CS_Linear) relative to the axis of the DOL. The angle E is defined by the following expression: E= Arc Tangent ((CS- CS_Linear)/(DOL_Linear)) (5)

In addition, the angle F is the angle formed by the second straight line a ₂₂ extending from the inflection point (DOL_TP, CS_TP) to the point of maximum compressive stress with respect to the axis of the DOL. The angle F is defined by the following expression: F= Arc Tangent ((CS- CS_TP)/(DOL_TP)) (6)

Considering expressions (5) and (6), the range of the ratio of the angles related to the treatment time of the chemical strengthening process is defined as: |(E/F) -(E-F)|^0.5 ≦ 4

The ratio of angles E and F as stated above is proportional to the treatment time of the chemical strengthening process. The higher the value of the ratio expressed above, the longer the treatment time of the chemical strengthening process.

In some embodiments, the desired value of the strength of the glass can be obtained by tuning the dual ion exchange process as required. The double ion exchange process is used to chemically strengthen the glass. During this process, smaller ions on the surface layer of the glass exchange with larger ions of the same valence or oxidation state that are present in the glass. This ion exchange, preferably the exchange of metal cations, is carried out in a salt bath, wherein the larger cations from the salt bath replace the smaller cations of the glass. This ion exchange typically begins at the top surface of the glass and extends to a depth below the top surface. This ion exchange process creates compressive stress in the region from the top surface to the depth of the glass. This compressive stress increases tensile stress, which strengthens the glass material.

For example, in the double ion exchange process of lithium aluminosilicate glass materials, the alkali metal ions to be replaced are lithium ions (Li+). The salt baths preferably used are sodium ion (Na+) baths and potassium ion (K+) baths. More preferably, the salt bath contains salts _of NaNO3 and _KNO3 , respectively. In the first step of ion exchange, lithium ions are replaced by sodium ions inside the surface of the glass material. Furthermore, in the second step of ion exchange, lithium or sodium ions are replaced by potassium ions inside the surface of the glass material.

The glass used is an alkali metal aluminosilicate glass with a thickness in the range of 20 microns to 2 mm. Samples of alkali metal aluminosilicate glass with a thickness of 0.7 mm were ion exchanged in a first ion exchange bath (step 1) under the conditions listed in Table 1, followed by ion exchange in a second ion exchange bath ( step 2).

Table 1 illustrates different reaction conditions and compressive stress (CS)-depth of layer (DOL) values for each step of the dual ion exchange process for exemplary glass compositions. S.No. grass Step 1 _ Step 2 _ Step 1 _ Step 2 _ Fitting data for steps 1 and 2 KNO ₃ (wt%) Temperature ( °C) Time (Min.) KNO ₃ (wt%) Temperature ( °C) Time (Min.) CS (MPa) DOL_Zero (μm) CS (MPa) DOL /DOL_TP (μm) CS (MPa) DOL_Zero /DOC ( μm ) CS_TP/ CS _k (MPa) DOL_TP/DOL (μm) 1 16 60% 380 60 90% 360 30 219.63 109.84 955.86 6.50 951.34 107.89 69.43 17.20 2 16 60% 380 127 90% 380 49 259.63 121.98 964.36 10.30 961.71 113.78 75.23 21.83 3 16 60% 380 300 90% 380 60 295.14 120.23 946.85 14.50 947.68 115.17 70.40 20.73 4 16 60% 390 240 100% 390 12 147.89 161.09 1261.68 13.25 1183.72 121.72 327.12 5.18 5 16 60% 390 360 100% 420 36 229.55 124.99 1175.49 19.66 1124.88 90.58 45.16 25.23 6 16 60% 380 120 90% 420 240 478.73 65.77 719.84 31.67 694.38 72.41 25.21 44.15 7 16 60% 380 40 100% 420 240 645.28 46.92 915.68 35.63 1190.56 47.62 4.82 45.58 8 8 60% 380 40 90% 360 240 135.80 145.79 947.96 6.98 887.65 111.27 221.87 8.05 9 8 60% 380 30 90% 380 270 141.56 157.91 645.30 9.01 596.54 120.52 328.25 3.73 10 8 60% 380 120 90% 380 40 148.55 139.17 658.30 6.04 629.95 95.20 106.70 26.38 11 8 60% 380 120 90% 380 45 96.67 180.67 753.22 8.77 758.75 172.14 90.27 10.05 12 8 60% 380 120 100% 420 90 101.38 179.63 1013.88 16.46 1013.88 152.74 105.22 25.83 13 8 60% 420 240 90% 380 90 103.68 209.10 719.21 15.39 724.44 199.95 102.29 15.50 14 8 60% 420 240 100% 420 45 96.84 189.14 1025.63 17.44 1030.28 173.64 91.39 18.38 15 8 80% 380 240 90% 420 45 97.03 190.80 774.74 14.50 755.60 182.33 91.58 17.08 16 8 80% 380 240 100% 380 90 92.75 184.56 1051.77 12.16 1060.65 162.41 76.30 14.60 17 8 80% 420 120 90% 420 90 104.56 182.70 732.43 17.83 737.17 167.99 98.30 22.08 18 8 80% 420 120 100% 380 45 104.57 177.55 1064.14 13.33 1071.26 165.88 90.49 12.35 19 8 60% 390 240 100% 390 12 95.21 194.55 1082.72 10.59 1082.72 180.73 99.88 12.20 20 8 60% 390 360 100% 420 36 105.99 161.54 1043.34 14.69 1055.00 162.69 84.51 16.53 twenty one 8 60% 380 120 90% 420 240 119.53 163.51 752.47 19.75 - - - - twenty two 8 60% 380 120 100% 420 240 151.33 153.73 982.20 24.11 982.20 143.80 115.95 33.33 twenty three 8 60% 380 40 100% 420 240 184.90 136.73 964.19 22.17 983.84 147.48 119.56 32.30 twenty four 8 60% 380 120 90% 380 40 95.33 174.79 714.11 6.74 714.10 176.44 271.64 2.03 25 61 60% 390 240 100% 390 12 115.56 173.60 1294.08 6.69 1295.80 171.40 109.26 5.00 26 61 60% 390 240 100% 390 12 115.60 181.66 1277.01 7.79 1285.90 160.90 81.99 6.43 27 61 60% 390 240 100% 390 12 125.07 167.66 1290.83 7.56 1290.90 168.50 116.71 5.70 28 61 60% 390 240 100% 390 12 130.58 182.29 1299.07 6.75 1320.20 179.10 125.29 5.55 29 16 60% 390 240 100% 390 12 139.17 134.01 1284.95 12.16 1284.96 134.45 119.29 9.35 30 16 60% 390 240 100% 390 12 137.49 145.93 133.70 11.69 1332.31 144.93 119.27 8.38 31 16 60% 390 240 100% 390 12 135.39 145.68 1309.90 11.68 1311.40 145.57 119.52 8.78 32 16 60% 380 120 100% 380 40 125.52 159.03 853.06 8.24 853.10 182.10 103.85 6.50 33 13 60% 380 40 90% 360 240 125.52 159.03 626.68 14.15 626.70 164.50 99.15 14.88 34 13 60% 380 30 90% 380 270 138.55 141.86 625.26 19.34 626.80 147.20 99.88 18.50 35 13 60% 380 120 90% 380 40 110.59 111.71 623.69 11.62 623.90 113.30 79.06 8.83 36 15 60% 380 120 90% 380 40 92.68 150.29 634.77 9.77 635.40 150.60 76.85 10.53 37 61 60% 380 120 100% 420 240 120.45 105.46 1062.69 22.10 1062.70 101.70 78.94 25.85 38 8 60% 390 180 100% 390 36 78.92 148.92 1249.80 9.12 1251.24 142.75 68.68 10.45 39 8 60% 390 240 100% 390 12 84.59 150.10 1248.59 8.52 1249.78 138.73 84.35 6.18 40 8 60% 390 240 100% 390 36 75.12 149.64 1221.06 9.75 1222.40 135.93 63.58 9.68 41 8 60% 390 300 100% 390 12 101.50 142.73 1207.93 9.57 1209.04 144.01 84.61 7.08 42 8 60% 390 300 100% 390 36 85.52 150.74 1236.47 10.70 1237.89 147.68 77.47 10.48 43 80 40% 415 110 97% 380 20 213.48 98.80 970.43 6.55 970.43 99.52 248.06 4.43 44 80 40% 415 110 97% 380 20 210.89 92.68 996.12 5.28 996.12 92.59 248.22 6.13 45 62 60% 390 240 100% 390 12 106.25 160.36 1251.86 7.66 1253.48 145.45 99.79 10.65 46 62 60% 390 240 100% 390 12 106.25 162.25 1275.00 8.34 1276.57 161.69 103.53 5.33 47 61 60% 380 180 90% 380 35 120.40 172.68 850.29 6.87 850.50 172.23 110.19 5.68 48 8 60% 380 180 90% 380 35 87.43 145.17 835.58 9.73 836.73 145.92 75.58 10.50 49 16 60% 380 180 90% 380 35 164.38 105.19 880.31 12.48 880.31 107.56 175.38 10.53 50 61 50% 390 240 90% 380 150 114.28 161.83 846.54 10.01 848.23 158.80 108.21 9.58 51 8 50% 390 240 90% 380 150 95.14 137.05 825.23 14.49 827.21 138.94 73.71 15.98 52 16 50% 390 240 90% 380 150 166.86 109.37 863.32 17.79 864.59 112.54 120.13 16.10 53 79 40% 415 110 97% 380 20 173.03 120.93 1120.12 6.38 1124.06 102.26 96.37 15.53 54 79 40% 415 110 97% 380 20 168.00 116.09 1113.59 6.41 1114.13 113.29 163.79 5.38 55 62 60% 390 240 100% 390 12 94.06 156.29 1221.15 6.12 1228.89 141.26 68.93 5.35 56 62 60% 390 240 100% 390 12 91.22 151.87 1247.02 6.26 1247.93 149.36 89.23 4.75 57 62 60% 390 240 100% 390 12 96.68 153.03 1242.59 7.13 1244.01 145.65 91.33 10.93 58 16 60% 390 240 100% 390 12 105.36 156.69 1309.62 4.71 1310.41 155.90 100.45 5.30 59 16 60% 390 240 100% 390 12 112.58 153.72 1263.25 7.44 1264.23 154.61 104.87 6.13 60 16 60% 390 240 100% 390 12 117.31 151.50 1296.09 8.18 1296.48 152.04 112.20 5.53 61 16 60% 390 240 100% 390 12 111.95 155.95 1269.06 8.04 1270.49 156.51 106.45 5.85 62 63 60% 380 120 100% 420 90 124.41 110.88 1154.36 13.87 1157.33 111.80 67.58 18.93 63 63 60% 380 120 100% 420 90 102.40 122.93 1146.03 13.59 1149.24 121.35 72.88 18.93 64 63 60% 380 120 100% 420 90 116.25 123.77 1164.63 13.95 1168.09 118.44 62.92 21.33 65 63 60% 380 120 100% 420 90 68.09 137.70 1162.23 13.83 1162.45 121.02 47.02 20.70 66 62 60% 380 120 100% 420 90 152.04 109.12 1150.95 14.43 1153.97 112.51 67.68 19.90 67 62 60% 380 120 100% 420 90 138.04 104.76 1157.32 15.00 1160.27 107.03 67.48 20.25 68 62 60% 390 240 100% 390 12 113.68 149.43 1288.64 6.70 1290.18 149.99 105.01 4.98 69 62 60% 390 240 100% 390 12 110.16 152.24 1273.40 6.86 1273.81 150.79 99.21 4.88 70 62 60% 390 240 100% 390 12 108.57 146.04 1268.85 6.96 1270.17 146.16 97.77 5.00 71 62 60% 390 240 100% 390 12 106.77 149.59 1287.42 6.81 1289.04 148.95 99.68 4.88 72 62 60% 390 240 100% 390 12 110.97 152.26 1359.23 6.02 1365.64 146.91 92.37 4.55 73 62 60% 390 240 100% 390 12 110.68 147.79 1299.97 6.05 1301.20 147.31 102.66 4.75 74 62 60% 390 240 100% 390 12 108.00 148.00 1279.40 6.70 1280.79 147.77 98.99 4.83 75 62 60% 390 240 100% 390 12 113.11 154.01 1311.64 5.05 1311.84 152.54 102.88 5.53 76 62 60% 390 240 100% 390 12 112.06 149.35 1297.15 5.59 1298.36 149.66 100.01 4.70 Table 1: Exemplary glass samples with DOC and CS for each step of the dual ion exchange process

In an exemplary embodiment, the first ion-exchanged salt bath includes NaNO ₃ in the range of 5-95 wt % and KNO ₃ in the range of 5-95 wt %. The preferred temperature for treating the glass material is greater than 300°C, and the time for treating the glass material is at least 0.25 hours. The stress profile for the first step of ion exchange includes compressive stress in the range of 60 MPa to 650 MPa and layer depth in the range of 45 μm to 210 μm. The second ion exchanged salt bath contains _KNO3 in the range of 50 to 100 wt% and NaNO3 in the range _of 0 to 50 wt%. The preferred temperature for treating the glass material is greater than 300°C, and the time for treating the glass material is about 0.1 hour to 6.5 hours. The stress profile for the second step of ion exchange included compressive stress in the range of 130 MPa to 1400 MPa and layer depth less than 60 μm. Immersion in the second ion exchange bath increased the compressive stress of all samples according to the method described above.

In one embodiment, the chemical strengthening process of the glass is achieved at a chemical tempering temperature less than 50°C below the transition temperature (Tg) and a total chemical tempering time greater than or equal to 2 hours. For the chemical strengthening process of glass, the values of CS, CS_TP, DOL_TP and DOL_ZERO are obtained from the fitting results of FSM-6000 and SLP-1000 (SLP-2000).

Table 2 illustrates the various values of stress area and angle obtained by the compressive stress-depth of layer (CS-DOL) distribution of the dual ion exchange process described in Table 1 of exemplary glass compositions. S.No. grass A B |(A/B)|^0.5 C D |(C/D)|^0.5 E F |(E/F) -(EF)|^0.5 1 16 4939.35 9375.66 0.7 38199.69 13120.88 1.7 - 1.5513 - 2 16 5921.49 12136.45 0.7 38297.46 16416.15 1.5 - 1.5462 - 3 16 5512.64 11279.30 0.7 39238.28 15332.98 1.6 - 1.5472 - 4 16 21602.29 4755.75 2.1 47378.58 24665.17 1.4 - 1.5648 - 5 16 3184.81 15326.76 0.5 33575.02 17372.31 1.4 - 1.5474 - 6 16 2025.99 16441.50 0.4 7785.54 17354.34 0.7 - 1.5049 - 7 16 334.44 27349.51 0.1 883.50 27464.28 0.2 - 1.5324 - 8 8 14129.57 5358.82 1.6 31680.90 17702.34 1.3 - 1.5587 - 9 8 21003.41 2333.78 3.0 13834.46 22114.48 0.8 - 1.5569 - 10 8 7892.79 11121.66 0.8 13783.82 16200.27 0.9 - 1.5204 - 11 8 8676.57 4719.93 1.4 52814.80 12489.29 2.1 - 1.5558 - 12 8 10752.50 15808.98 0.8 53585.54 23844.27 1.5 - 1.5424 - 13 8 11812.40 7199.97 1.3 54999.08 17426.81 1.8 - 1.5459 - 14 8 9613.42 11144.93 0.9 70368.09 19079.10 1.9 - 1.5512 - 15 8 9912.97 8014.66 1.1 52521.17 16363.87 1.8 - 1.5451 - 16 8 7309.50 8856.63 0.9 71076.94 15052.21 2.2 - 1.5560 - 17 8 10427.15 10306.59 1.0 43356.26 18563.69 1.5 - 1.5363 - 18 8 8622.74 7732.54 1.1 73612.76 15237.75 2.2 - 1.5582 - 19 8 10243.84 7823.12 1.1 80990.11 16848.44 2.2 - 1.5584 - 20 8 8270.69 10113.38 0.9 68832.26 16987.61 2.0 - 1.5538 - twenty one 8 - - - - - - - - - twenty two 8 12200.51 20230.43 0.8 42051.14 28566.86 1.2 - 1.5323 - twenty three 8 12678.02 19750.85 0.8 43980.51 28567.09 1.2 - 1.5334 - twenty four 8 24514.60 1273.09 4.4 37761.70 25237.63 1.2 - 1.5662 - 25 61 9909.79 3785.79 1.6 97900.77 13149.29 2.7 1.5668 1.5666 1.0000 26 61 7122.88 4657.74 1.2 92196.82 11253.83 2.9 1.5671 1.5655 0.9997 27 61 10497.70 4344.29 1.6 94581.55 14176.77 2.6 1.5664 1.5659 0.9999 28 61 11915.17 4358.92 1.7 102645.18 15578.73 2.6 1.5664 1.5662 1.0000 29 16 9134.50 7122.50 1.1 71241.55 15141.68 2.2 1.5634 1.5628 0.9999 30 16 9641.26 6577.88 1.2 81323.99 15220.30 2.3 1.5647 1.5639 0.9998 31 16 9747.97 6802.57 1.2 79945.88 15501.74 2.3 1.5662 1.5634 0.9995 32 16 10130.76 3447.61 1.7 64771.42 12903.34 2.2 1.5625 1.5621 0.9999 33 13 9630.33 6135.99 1.3 37254.66 14291.41 1.6 1.5510 1.5426 0.9985 34 13 9198.67 7645.62 1.1 31135.91 14996.57 1.4 1.5461 1.5357 0.9982 35 13 5176.39 3450.65 1.2 27414.59 7929.35 1.9 1.5611 1.5546 0.9988 36 15 6595.39 4152.61 1.3 37906.43 9939.19 2.0 1.5566 1.5520 0.9992 37 61 6055.00 15776.10 0.6 34247.89 19790.40 1.3 1.5536 1.5445 0.9984 38 8 5619.77 7255.44 0.9 77147.06 12157.48 2.5 1.5627 1.5620 0.9999 39 8 6371.38 4379.51 1.2 76459.96 10230.06 2.7 1.5659 1.5655 0.9999 40 8 4936.71 6528.53 0.9 72232.85 10850.08 2.6 1.5633 1.5624 0.9998 41 8 6690.64 4875.56 1.2 76089.10 10967.61 2.6 1.5654 1.5645 0.9998 42 8 6531.58 7294.88 0.9 78392.49 13015.02 2.5 1.5618 1.5618 1.0000 43 80 13441.56 3244.74 2.0 32701.23 15588.62 1.4 1.5494 1.5647 1.0027 44 80 13011.44 4570.95 1.7 30052.10 16062.05 1.4 1.5434 1.5626 1.0034 45 62 8320.17 7737.56 1.0 76162.16 14994.93 2.3 1.5639 1.5616 0.9996 46 62 8921.32 3950.17 1.5 90884.68 12320.18 2.7 1.5676 1.5663 0.9998 47 61 10114.93 3038.66 1.8 60714.62 12528.23 2.2 1.5656 1.5631 0.9996 48 8 6307.57 5186.39 1.1 50347.55 10700.42 2.2 1.5614 1.5570 0.9992 49 16 11277.70 6478.52 1.3 31431.86 15910.33 1.4 1.5589 1.5559 0.9995 50 61 9628.31 5097.02 1.4 53660.38 13689.19 2.0 1.5613 1.5579 0.9994 51 8 6297.77 7784.77 0.9 44560.57 12905.09 1.9 1.5578 1.5496 0.9985 52 16 8693.69 8893.99 1.0 32998.76 15653.67 1.5 1.5526 1.5492 0.9994 53 79 6424.02 10224.95 0.8 42320.84 15152.35 1.7 1.5605 1.5557 0.9991 54 79 10159.07 3878.20 1.6 49953.81 13156.08 1.9 - 1.5651 - 55 62 5237.34 3656.05 1.2 78272.23 8524.61 3.0 1.5681 1.5662 0.9997 56 62 7087.55 3387.67 1.4 83145.36 10051.38 2.9 1.5683 1.5667 0.9997 57 62 7648.54 7793.15 1.0 76148.40 14443.93 2.3 1.5684 1.5613 0.9987 58 16 8361.84 4004.94 1.4 90309.26 11834.43 2.8 1.5668 1.5664 0.9999 59 16 8749.38 4514.05 1.4 85106.98 12621.08 2.6 1.5656 1.5655 1.0000 60 16 9149.59 4201.44 1.5 85827.14 12731.11 2.6 1.5669 1.5661 0.9999 61 16 8952.56 4338.89 1.4 86753.53 12668.74 2.6 1.5677 1.5658 0.9996 62 63 5056.79 12230.22 0.6 48686.14 16008.02 1.7 1.5597 1.5534 0.9989 63 63 5801.21 12253.96 0.7 53053.77 16675.91 1.8 1.5596 1.5532 0.9989 64 63 5067.94 13796.54 0.6 51654.07 17522.73 1.7 1.5597 1.5515 0.9985 65 63 3818.78 13004.73 0.5 54490.87 15850.14 1.9 1.5601 1.5522 0.9986 66 62 5153.98 12828.79 0.6 48280.02 16635.99 1.7 1.5596 1.5525 0.9987 67 62 4977.43 13114.12 0.6 45367.84 16725.17 1.6 1.5588 1.5523 0.9988 68 62 8397.07 3731.73 1.5 85147.58 11606.39 2.7 1.5671 1.5666 0.9999 69 62 7963.48 3588.54 1.5 84970.93 11068.38 2.8 1.5671 1.5666 0.9999 70 62 7634.19 3664.29 1.4 82014.40 10809.62 2.8 1.5671 1.5665 0.9999 71 62 7909.95 3627.98 1.5 84950.20 11051.97 2.8 1.5669 1.5667 1.0000 72 62 7205.15 3527.10 1.4 90003.30 10311.98 3.0 1.5679 1.5672 0.9999 73 62 8049.29 3577.99 1.5 84702.48 11139.65 2.8 1.5672 1.5668 0.9999 74 62 7791.38 3567.54 1.5 83747.53 10881.30 2.8 1.5671 1.5667 0.9999 75 62 8414.75 4192.36 1.4 88013.36 12038.71 2.7 1.5666 1.5662 0.9999 76 62 7953.72 3521.20 1.5 86149.46 11004.87 2.8 1.5675 1.5669 0.9999 Table 2: Stress Area and Angle Values for CS-DOL Distributions of Exemplary Glass Compositions

In one example, the glass used is lithium aluminosilicate glass. In the first ion exchange, the alkali metal bath contained 40 wt % NaNO ₃ and 60 wt % KNO ₃ . The glass substrate was immersed in an alkali metal bath at a temperature of 380°C for a period of 2 hours. The glass experienced a compressive stress of 95.33 MPa corresponding to a depth of 174.79 μm. After immersion in the first bath, a second ion exchange treatment of the glass was performed. The second ion exchange bath contained 10 wt % NaNO ₃ and 90 wt % KNO ₃ . The glass substrate was immersed in the second ion exchange bath at a temperature of 380°C for 40 minutes. The material experienced a compressive stress of 714.11 MPa corresponding to a depth of 6.74 μm. The strength of the glass is increased after the glass has been chemically strengthened by the methods described above. Since the values of CS, CS_TP, DOL_TP and DOL_ZERO are derived from the fitting results of FSM-6000 and SLP-1000 (SLP-2000), the fitting values obtained in this exemplary embodiment are: the maximum compressive stress CS is 714.10 MPa, the compression The depth DOL_ZERO is 176.44 μm, the compressive stress at the inflection point CS_TP is 271.64 MPa, and the layer depth at the inflection point DOL_TP is 2.03 μm. The stress area and angle are then determined from the CS, CS_TP, DOL_TP, and DOL_ZERO values. The ratio of the first compressive stress A to the second compressive stress B (|(A/B)|^0.5) was 4.4. The ratio of the third compressive stress C to the fourth compressive stress D (|(C/D) |^0.5) was 1.2. Since the ratio of the first compressive stress A to the second compressive stress B has a higher value, the chemically strengthened glass has higher strength.

The dual ion exchange process described is primarily affected by the composition of the glass. Therefore, the composition of the glass is an important factor to consider before it undergoes the strengthening process. A suitable glass composition helps to optimize the chemical strengthening process, herein a dual ion exchange process.

The present invention describes the optimum molar % of the various components of the composition. The glass composition comprises about 50 mol % to about 75 mol % SiO ₂ , about 5 mol % to about 25 mol % Al ₂ O ₃ , about 0 mol % to about 10 mol % B _{2 O3} , about 0 mol% to about 15 mol% Na2O, about ₅ mol% to about 17 mol% _Li2O , about 0 mol% to about ₂ mol% K2O , about 0 mol % to about 7 mol % MgO, about 0 mol % to about 3 mol % CaO, about 0 mol % to about 7 mol % P ₂ O ₅ , about 0 mol % % to about 7 mol % ZnO and about 0 mol % to about 7 mol % ZrO ₂ . The glass composition also includes one or more refining agents, for example, about 0 mol % to about 2.5 mol % SnO ₂ , about 0 mol % to about 2.5 mol % Fe ₂ O ₃ , about 0 mol % To about ₂ mol% CeO2, and other refining agents such as chlorides and sulfates. Additionally, the glass composition further includes about 0 mol% to about 2 mol% _TiO2 .

Table 3 illustrates non-limiting, exemplary compositions of exemplary chemically strengthened glasses of the present invention. Source materials for alkali metal oxides and alkaline earth metal oxides are selected from the group consisting of carbonates and nitrates. For example, in Tables 3-8 below, Na2O ₍ C) defines the source material for sodium (Na) as sodium carbonate. Similarly, Na2O ₍ N) defines the source material for sodium (Na) as sodium nitrate. mol % 1 2 3 4 5 6 7 8 9 10 11 12 13 14 _SiO2 67.28 65.67 66.03 66.28 67.47 67.14 65.91 64.41 64.41 64.41 66.01 64.91 65.91 64.71 Al ₂ O ₃ 10.18 13.37 13.36 13.52 9.86 9.86 12.00 12.00 12.00 12.00 12.00 12.00 12.00 12.00 B ₂ O ₃ 4.26 0.00 0.00 0.00 0.00 0.00 0.00 1.50 2.00 1.50 1.50 1.50 2.00 1.50 Na ₂ O (C) 9.40 10.99 11.13 11.04 10.87 10.76 10.00 10.00 10.00 10.00 10.00 10.00 10.00 10.00 Na ₂ O (N) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Li ₂ O (C) 5.56 5.27 5.42 5.46 8.34 8.47 6.50 6.50 6.50 6.50 6.50 6.50 6.50 6.50 K ₂ O (C) 0.43 0.00 0.00 0.00 0.72 1.19 0.00 0.00 1.00 0.50 0.90 0.70 0.90 0.70 MgO (C) 0.00 0.00 3.08 0.00 2.64 2.48 0.00 0.00 2.00 3.00 1.00 1.10 0.50 0.70 CaO (C) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 ZnO 2.81 3.52 0.00 2.93 0.00 0.00 3.52 3.52 0.00 0.00 0.00 1.20 0.00 1.80 ZrO ₂ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 SnO ₂ 0.080 0.080 0.080 0.080 0.100 0.100 0.080 0.080 0.080 0.080 0.080 0.080 0.080 0.080 Fe ₂ O ₃ 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 P ₂ O ₅ 0.00 1.10 0.90 0.70 0.00 0.00 2.00 2.00 2.00 2.00 2.00 2.00 2.10 2.00 TiO ₂ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 total 100.00 100.00 100.00 100.01 100.00 100.00 100.01 100.01 99.99 99.99 99.99 99.99 99.99 99.99 R ₂ O 15.39 16.26 16.55 16.50 19.93 20.42 16.50 16.50 17.50 17.00 17.40 17.20 17.40 17.20 RO 0.00 0.00 3.08 0.00 2.64 2.48 0.00 0.00 2.00 3.00 1.00 1.10 0.50 0.70 Al ₂ O ₃ / R ₂ O 0.66 0.82 0.81 0.82 0.49 0.48 0.73 0.73 0.69 0.71 0.69 0.7 0.69 0.70 Table 3: Exemplary Compositions of Chemically Strengthened Glasses Table 4 illustrates non-limiting, exemplary compositions of exemplary chemically strengthened glasses of the present invention. mol % 15 16 17 18 19 20 twenty one twenty two twenty three twenty four 25 26 27 28 _SiO2 64.71 61.85 63.61 65.90 65.90 65.98 67.05 68.91 65.74 70.88 72.23 71.90 71.13 69.12 Al ₂ O ₃ 12.00 16.19 14.00 8.50 8.50 8.51 10.46 10.60 15.26 9.32 9.16 9.40 9.56 13.54 B ₂ O ₃ 1.50 0.00 1.50 0.00 0.00 0.00 0.00 0.00 0.41 1.15 1.53 3.05 1.66 2.42 Na ₂ O (C) 10.00 11.89 10.00 10.40 10.40 10.41 10.46 8.70 8.65 5.58 5.67 5.96 5.37 6.40 Na ₂ O (N) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Li ₂ O (C) 6.50 6.49 6.50 12.10 12.10 12.11 10.69 8.80 7.40 8.09 8.49 8.93 7.98 6.88 K ₂ O (C) 0.90 0.00 0.50 0.00 0.00 0.00 0.11 0.00 0.00 0.10 0.18 0.00 0.32 0.00 MgO (C) 0.50 0.00 0.20 2.90 0.00 0.00 1.13 0.00 0.30 4.68 0.00 0.00 3.78 1.26 CaO (C) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 ZnO 1.80 1.20 1.60 0.00 2.90 0.00 0.00 0.00 0.00 0.00 2.66 0.68 0.00 0.00 ZrO ₂ 0.00 0.00 0.00 0.00 0.00 2.90 0.00 2.90 0.00 0.00 0.00 0.00 0.00 0.00 SnO ₂ 0.080 0.080 0.080 0.200 0.200 0.080 0.100 0.080 0.200 0.200 0.080 0.080 0.200 0.200 Fe ₂ O ₃ 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 P ₂ O ₅ 2.00 2.30 2.00 0.00 0.00 0.00 0.00 0.00 2.05 0.00 0.00 0.00 0.00 0.19 TiO ₂ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 total 99.99 100.00 99.99 100.00 100.00 99.99 100.00 99.99 100.01 100.00 100.00 100.00 100.00 100.01 R ₂ O 17.40 18.38 17.00 22.50 22.50 22.52 21.26 17.50 16.05 13.77 14.34 14.89 13.67 13.28 RO 0.50 0.00 0.20 2.90 0.00 0.00 1.13 0.00 0.30 4.68 0.00 0.00 3.78 1.26 Al ₂ O ₃ / R ₂ O 0.69 0.88 0.82 0.38 0.38 0.38 0.49 0.61 0.95 0.68 0.64 0.63 0.70 1.02 Table 4: Exemplary Compositions of Chemically Strengthened Glasses Table 5 illustrates non-limiting, exemplary compositions of exemplary chemically strengthened glasses of the present invention. mol % 29 30 31 32 33 34 35 36 37 38 39 40 41 42 _SiO2 71.17 62.20 67.28 68.02 67.37 64.10 62.94 69.92 61.61 60.04 64.00 68.18 69.45 69.45 Al ₂ O ₃ 9.48 16.58 10.18 13.94 10.89 15.00 13.79 12.60 14.90 12.04 15.98 14.56 14.50 14.50 B ₂ O ₃ 0.76 0.19 4.26 1.42 0.00 2.00 1.60 0.00 2.30 1.90 1.31 0.59 0.08 0.08 Na ₂ O (C) 5.49 9.00 5.99 7.21 6.06 6.30 6.58 6.22 6.90 5.85 6.20 5.95 5.19 5.19 Na ₂ O (N) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Li ₂ O (C) 8.45 8.22 8.97 8.03 9.09 8.00 9.88 10.55 10.40 12.19 9.90 10.47 10.12 10.13 K ₂ O (C) 0.00 0.83 0.43 0.00 0.00 0.80 0.83 0.00 0.00 0.00 0.00 0.00 0.00 0.00 MgO (C) 4.45 0.35 0.00 1.15 3.30 1.06 0.00 0.28 1.80 1.40 0.00 0.00 0.45 0.45 CaO (C) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.60 0.00 0.00 0.00 0.00 ZnO 0.00 0.00 2.81 0.00 0.00 0.66 2.00 0.00 0.00 0.00 1.13 0.00 0.00 0.00 ZrO ₂ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3.00 0.00 0.00 0.00 0.00 SnO ₂ 0.200 0.080 0.080 0.200 0.080 0.080 0.080 0.100 0.080 0.080 0.080 0.100 0.200 0.200 Fe ₂ O ₃ 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 P ₂ O ₅ 0.00 2.55 0.00 0.02 3.20 2.00 2.30 0.33 2.00 1.90 1.40 0.15 0.01 0.00 TiO ₂ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 total 100.00 100.00 100.00 99.99 99.99 100.00 100.00 100.00 99.99 100.00 100.00 100.00 100.00 100.00 R ₂ O 13.94 18.05 15.39 15.24 15.15 15.10 17.29 16.77 17.30 18.04 16.10 16.42 15.31 15.32 RO 4.45 0.35 0.00 1.15 3.30 1.06 0.00 0.28 1.80 3.00 0.00 0.00 0.45 0.45 Al ₂ O ₃ / R ₂ O 0.68 0.92 0.66 0.91 0.72 0.99 0.80 0.75 0.86 0.67 0.99 0.89 0.95 0.95 Table 5: Exemplary Compositions of Chemically Strengthened Glasses Table 6 illustrates non-limiting, exemplary compositions of exemplary chemically strengthened glasses of the present invention. mol % 43 44 45 46 47 48 49 50 51 52 53 54 55 56 _SiO2 61.85 70.85 67.47 67.54 71.22 67.14 66.88 67.14 64.06 64.65 61.05 63.00 64.14 64.12 Al ₂ O ₃ 16.19 13.88 14.49 9.89 12.87 9.99 11.05 10.89 12.91 12.59 13.99 12.00 12.50 12.00 B ₂ O ₃ 0.00 0.22 0.08 0.40 0.00 0.40 0.40 0.40 0.00 0.00 0.40 1.50 1.49 2.00 Na ₂ O (C) 6.49 3.99 4.64 3.50 3.94 3.50 3.51 3.50 3.48 3.50 3.50 10.00 8.37 8.40 Na ₂ O (N) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Li ₂ O (C) 11.89 9.95 11.11 12.59 10.92 13.89 12.65 12.99 13.51 14.19 16.39 8.30 7.91 7.90 K ₂ O (C) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 MgO (C) 0.00 0.91 0.18 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 CaO (C) 0.00 0.00 0.00 3.00 0.00 2.00 2.41 2.00 2.98 2.00 1.60 0.00 0.00 0.00 ZnO 1.20 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3.12 3.51 3.50 ZrO ₂ 0.00 0.00 0.00 3.00 0.00 3.00 3.01 3.00 2.98 3.00 3.00 0.00 0.00 0.00 SnO ₂ 0.080 0.200 0.200 0.080 0.200 0.080 0.080 0.080 0.080 0.080 0.080 0.082 0.083 0.082 Fe ₂ O ₃ 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 P ₂ O ₅ 2.30 0.00 1.84 0.00 0.87 0.00 0.00 0.00 0.00 0.00 0.00 2.00 1.99 2.00 TiO ₂ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 total 100.00 100.00 100.01 100.00 100.02 100.00 99.99 100.00 100.00 100.01 100.01 100.00 100.00 100.00 R ₂ O 18.38 13.94 15.75 16.09 14.86 17.39 16.16 16.49 16.99 17.69 19.89 18.30 16.28 16.30 RO 0.00 0.91 0.18 3.00 0.00 2.00 2.41 2.00 2.98 2.00 1.60 0.00 0.00 0.00 Al ₂ O ₃ / R ₂ O 0.88 1.00 0.92 0.61 0.87 0.57 0.68 0.66 0.76 0.71 0.70 0.66 0.77 0.74 Table 6: Exemplary Compositions of Chemically Strengthened Glasses Table 7 illustrates non-limiting, exemplary compositions of exemplary chemically strengthened glasses of the present invention. mol % 57 58 59 60 61 62 63 64 65 66 67 68 69 70 _SiO2 65.80 64.97 64.54 64.12 65.42 65.42 65.41 61.59 59.42 60.42 60.42 58.42 58.42 59.00 Al ₂ O ₃ 12.42 11.06 11.53 11.98 12.00 12.00 12.00 15.56 18.11 19.11 19.11 18.11 17.11 18.00 B ₂ O ₃ 2.00 1.99 1.99 1.50 1.78 1.78 1.78 0.34 4.20 3.20 3.20 5.20 5.20 4.50 Na ₂ O (C) 10.00 8.37 8.37 9.98 8.39 6.89 8.39 9.49 9.56 8.56 8.56 9.56 9.56 9.50 Na ₂ O (N) 0.00 0.00 0.00 0.00 0.00 1.50 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Li ₂ O (C) 6.50 7.87 7.87 6.82 6.82 6.82 6.82 7.26 6.35 6.35 5.35 6.35 7.35 6.50 K ₂ O (C) 0.80 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.14 0.14 0.14 0.14 0.14 0.22 MgO (C) 0.20 0.00 0.00 0.00 0.00 0.00 0.00 1.28 0.82 0.82 1.32 0.82 0.82 0.60 CaO (C) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 ZnO 0.00 3.49 3.49 3.51 3.51 3.51 3.51 2.04 0.00 0.00 0.00 0.00 0.00 0.00 ZrO ₂ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 SnO ₂ 0.082 0.082 0.082 0.082 0.082 0.073 0.082 0.040 0.020 0.020 0.020 0.020 0.023 0.080 Fe ₂ O ₃ 0.000 0.000 0.000 0.000 0.000 0.009 0.009 0.000 0.000 0.000 0.000 0.000 0.000 0.000 P ₂ O ₅ 2.20 2.18 2.18 2.00 2.00 2.00 2.00 2.40 1.37 1.37 1.87 1.37 1.37 1.60 TiO ₂ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 total 100.00 100.00 100.05 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 R ₂ O 17.30 16.24 16.24 16.80 15.21 15.21 15.21 16.75 16.05 15.05 14.05 16.05 17.05 16.22 RO 0.20 0.00 0.00 0.00 0.00 0.00 0.00 1.28 0.82 0.82 1.32 0.82 0.82 0.60 Al ₂ O ₃ / R ₂ O 0.72 0.68 0.71 0.71 0.79 0.79 0.79 0.93 1.13 1.27 1.36 1.13 1.00 1.11 Table 7: Exemplary Compositions of Chemically Strengthened Glasses Table 8 illustrates non-limiting, exemplary compositions of exemplary chemically strengthened glasses of the present invention. mol % 71 72 73 74 75 76 77 78 79 80 _SiO2 57.25 57.99 56.91 57.63 57.00 57.85 57.43 57.43 58.70 55.16 Al ₂ O ₃ 17.45 17.68 18.10 17.11 17.74 17.25 18.10 18.10 17.11 17.59 B ₂ O ₃ 5.41 6.44 7.10 7.10 6.00 5.20 5.20 5.20 5.77 4.24 Na ₂ O (C) 9.21 9.33 8.50 8.90 9.50 9.70 9.56 9.56 9.00 9.10 Na ₂ O (N) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Li ₂ O (C) 8.35 6.20 7.10 6.90 7.35 7.70 7.35 6.91 7.35 11.50 K ₂ O (C) 0.13 0.14 0.14 0.14 0.51 0.65 0.14 0.58 0.14 0.08 MgO (C) 0.79 0.80 0.76 0.82 0.45 0.45 0.82 0.82 0.48 1.14 CaO (C) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 ZnO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 ZrO ₂ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 SnO ₂ 0.084 0.085 0.023 0.023 0.080 0.025 0.023 0.025 0.075 0.020 Fe ₂ O ₃ 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 P ₂ O ₅ 1.32 1.34 1.37 1.37 1.37 1.37 1.37 1.37 1.37 1.07 TiO ₂ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0006 0.11 total 100.00 100.00 100.00 100.00 100.00 100.20 100.00 100.00 100.00 100.00 R ₂ O 17.69 15.67 15.74 15.94 17.36 18.05 17.05 17.05 16.49 20.68 RO 0.79 0.80 0.76 0.82 0.45 0.45 0.82 0.82 0.48 1.14 Al ₂ O ₃ / R ₂ O 0.99 1.13 1.15 1.07 1.02 0.96 1.06 1.06 1.04 0.85 Table 8: Exemplary Compositions of Chemically Strengthened Glasses

In an exemplary embodiment, a glass composition comprising about 65.42 mol % SiO ₂ , about 1.78 mol % B ₂ O ₃ , about 12.00 mol % Al ₂ O ₃ , About 6.89 mol% Na2O (C), about 1.5 mol% Na2O ₍ N), about 6.82 mol% _{Li2O (} C), about 3.51 mol% ZnO, about 0.073 mol% _SnO2 , about 0.009 mol % of Fe ₂ O ₃ and about 2.00 mol % of P ₂ O ₅ . In the first ion exchange, the alkali metal bath contained 40 wt % NaNO ₃ and 60 wt % KNO ₃ . The glass substrate was immersed in an alkali metal bath at a temperature of 390°C for a period of 4 hours. The glass experienced a compressive stress of 106.77 MPa corresponding to a depth of 149.59 μm. After immersion in the first bath, a second ion exchange treatment of the glass was performed. The second ion exchange bath contained 100 wt% _KNO3 . The glass substrate was immersed in the second ion exchange bath at a temperature of 390°C for 12 minutes. The material experienced a compressive stress of 1287.42 MPa corresponding to a depth of 6.81 μm. The strength of the glass is increased after the glass has been chemically strengthened by the methods described above. Since the values of CS, CS_TP, DOL_TP and DOL_ZERO are derived from the fitting results of FSM-6000 and SLP-1000 (SLP-2000), the fitting values obtained in this exemplary embodiment are: the maximum compressive stress CS is 1289.04 MPa, and the compressive stress is 1289.04 MPa. The depth DOL_ZERO is 148.95 μm, the compressive stress at the inflection point CS_TP is 99.68 MPa, and the layer depth at the inflection point DOL_TP is 4.88 μm. The stress area and angle are then determined from the CS, CS_TP, DOL_TP and DOL_ZERO values. The ratio of the first compressive stress A to the second compressive stress B (|(A/B)|^0.5) was 1.5. The ratio of the third compressive stress C to the fourth compressive stress D (|(C/D) |^0.5) was 2.8. The ratio of the angle E to F (|(E/F)-(EF)|^0.5) is 1.

The present invention provides chemical ion exchange glass for use as cover glass. Cover glass with high strength and high crack resistance is formed by chemical strengthening through a double ion exchange process. Unlike glass substrates strengthened by physical strengthening methods, cover glass is not prone to breakage. Specifically, the present invention describes stress-DOL distributions and formulates inequalities that are suitable for predicting glass strength and processing parameters, such as time and temperature.

Such chemically strengthened glass is used to protect the display screen of electronic devices. It is used in touch panel displays and display back covers such as Liquid Crystal Displays (LCD), Field Emission Displays (FED), Plasma Displays (PD), Electroluminescent Displays (ELD), Organic Light Emitting Diode (OLED) displays , Micro LED, etc. However, the cover glass is not limited to the aforementioned applications, and can also be used, for example, as a substrate for touch panel displays, cover glass for solar cells, disk substrates, signage substrates, window glass, building interiors and exteriors, automotive interior displays, and windshields Glass, windows associated with various modes of transport, etc.

In another embodiment, the cover glass is used as a protective window in connection with various modes of transportation, such as air, sea, or land, and for wind protection in non-transportation applications. Furthermore, it is used as fireproof glass. In addition, cover glass is also used as a substrate in hard disks. Furthermore, it can be used in semiconductor interposers and semiconductor carriers. By adding a nucleating agent, it can also be used as a cooktop in ceramified form. Finally, cover glass is used as a coated substrate in a variety of applications.

In a specific embodiment, the present invention also focuses on a back cover glass for protecting the back of electronic devices such as mobile phones, smart phones, tablet computers, wearable devices, digital cameras, and the like. In addition to providing strength to the device, the cover glass used on the back also requires enhanced electromagnetic radio signal transmission. For design reasons, a tinted opaque appearance may be possible. One way to accomplish this is to include one or more transition elements in the glass melt. The one or more transition elements may be Nb ₂ O ₅ , ZrO ₂ , Fe ₂ O ₃ , V ₂ O ₅ , Y ₂ O ₃ , MnO ₂ , NiO, CuO, Cr ₂ O ₃ , Co ₃ O ₄ , CoO, Co At least one of ₂ O ₃ and the like. In addition to the preparation of chemical ion exchange glasses, the present invention also facilitates the preparation of glass-based articles, such as glass ceramics. The above model facilitates the implementation of controlled devitrification to transform the glass into a predominantly crystalline glass-ceramic material. Such glass-ceramic compositions contain from about 0 mol% to about 6 mol% _TiO2 .

In another embodiment, the present invention is further focused on additional applications for the glass composition. Recently, as technology has advanced, glass has been molded to form 3D curved glass panels. The 3D curved glass plate has the advantages of light, thin, transparent, clean, anti-fingerprint, anti-glare, hard, scratch-resistant and weather-resistant. In addition, there is a trend to use 3D curved glass panels on display screens of electronic devices such as mobile phones. In addition, these glasses not only protect or improve the display, but also provide enhanced electron transport.

The present invention provides a cover glass with higher performance strength, better service life, higher crack resistance and higher sharp impact strength by chemical strengthening treatment through a double ion exchange process. Furthermore, this disclosure describes expressions for calculating the area under the curve and the angle formed by the tangent to the curve. The CS-DOL distribution describes the stress area and various reaction parameters, such as the time and temperature of the double ion exchange process. The CS-DOL distribution helps to understand and adjust the strengthening process parameters to obtain suitable glass materials.

While typical embodiments have been described for purposes of illustration, the foregoing description should not be construed as limiting the scope of the invention or the scope of the appended claims. Accordingly, various modifications, adaptations, and substitutions can be made by those skilled in the art without departing from the spirit and scope of the present invention.

The features of the invention believed to be novel are precisely set forth in the appended claims. Embodiments of the invention will be described herein in conjunction with the accompanying drawings, which are provided for the purpose of illustration and not to limit the scope of the claims, wherein like numerals refer to like elements, and wherein:

1 is a graph illustrating a compressive stress-ion exchange layer depth (CS-DOL) profile corresponding to a double ion exchange strengthening process of an alkali metal aluminosilicate glass according to an exemplary embodiment of the present invention;

2 is a graph illustrating a CS-DOL profile showing compressive stress areas formed by a double ion exchange strengthening process of alkali metal aluminosilicate glasses, according to an exemplary embodiment of the present invention; and

3 is a graph illustrating a CS-DOL profile estimating the timing of the first and second steps of the double ion exchange strengthening process of alkali metal aluminosilicate glass according to an exemplary embodiment of the present invention.

Claims (14)

A chemically strengthened glass comprising: an alkali metal aluminosilicate glass subjected to a double ion exchange process; and a compressive stress-depth of layer (CS-DOL) distribution of the double ion exchange process of the alkali metal aluminosilicate glass, The CS-DOL profile comprises: a first curve a ₁ , which defines the first step of ion exchange of the alkali metal aluminosilicate glass; a second curve a ₂ , which defines the second step of the alkali metal aluminosilicate glass Ion exchange, where the first curve a ₁ and the second curve a ₂ intersect at an inflection point (DOL_TP, CS_TP) in the CS-DOL distribution, where the first curve a ₁ is from the compression depth point (DOL_ZERO, 0) extends to the inflection point, wherein the second curve a ₂ extends from the point of maximum compressive stress (0, CS) to the inflection point, and wherein the first curve a ₁ is extrapolated to the first straight line a ₁₁ and the second curve a ₂ is outside Pushed to the second straight line a ₂₂ ; the first area under the first straight line a ₁₁ , which defines the first compressive stress area A of the first step ion exchange of the alkali metal aluminosilicate glass, wherein the first compressive stress Area A is the area of the first trapezoid as defined by the following expression: A = (CS_TP x DOL_ZERO x 0.5) + (CS_TP x DOL_TP), where DOL_ZERO and DOL_TP are expressed in micrometers (μm), CS_TP is expressed in MPa, and DOL_ZERO >DOL_TP; and the second area under the second straight line a ₂₂ , which defines the second compressive stress area B of the second-step ion exchange of the alkali metal aluminosilicate glass, wherein the second compressive stress area B is as follows The second trapezoid area is defined by the following expression: B = (CS x DOL_TP x 0.5) + (CS_TP x DOL_TP), where CS and CS_TP are expressed in MPa, DOL_TP is expressed in micrometers (μm), and CS>CS_TP, where the The ratio of the first compressive stress area and the second compressive stress areas A and B is within the range as defined by the following expression: 0.1≦|(A/B)|^0.5≦5.2. The chemically strengthened glass of claim 1, the CS-DOL distribution comprises: the first straight line a ₃₃ extending from the compression depth point to the maximum compressive stress point, the first straight line a ₁₁ and the second straight line a ₂₂ Three regions defining a third compressive stress area C, where the third compressive stress area C is defined by the following expression: C = (CS x DOL_ZERO x 0.5) - (CS_TP x DOL_ZERO x 0.5 + CS_TP x DOL_TP + CS x DOL_TP x 0.5), where CS and CS_TP are expressed in MPa and DOL_ZERO and DOL_TP are expressed in micrometers (μm); and a fourth area under the first straight line a ₁₁ and the second straight line a ₂₂ , which defines a fourth compressive stress area D , where the fourth compressive stress area D is defined by the following expression: D = (CS_TP x DOL_ZERO x 0.5 + CS_TP x DOL_TP + CS x DOL_TP x 0.5), where CS and CS_TP are expressed in MPa and DOL_ZERO and DOL_TP are expressed in micrometers (μm ) represents where the ratio of the third compressive stress area and the fourth compressive stress area C and D is within the range as defined by the following expression: 0.2 ≦ |(C/D) |^0.5 ≦ 6, and where the The ratio of the third compressive stress area and the fourth compressive stress area C and D is inversely proportional to the reaction temperature and duration of the first step ion exchange and the second step ion exchange of the alkali metal aluminosilicate glass. The chemically strengthened glass of claim 1, wherein in the first step of ion exchange of the alkali metal aluminosilicate glass, the compressive stress of the chemically strengthened glass is in the range of 60 MPa to 650 MPa. The chemically strengthened glass of claim 1, wherein in the second step of ion exchange of the alkali metal aluminosilicate glass, the compressive stress of the chemically strengthened glass is in the range of 130 MPa to 1400 MPa. The chemically strengthened glass of claim 1, wherein in the first step of ion exchange of the alkali metal aluminosilicate glass, the layer depth of the chemically strengthened glass is in the range of 45 μm to 210 μm. The chemically strengthened glass of claim 1, wherein in the second step of ion exchange of the alkali metal aluminosilicate glass, the layer depth of the chemically strengthened glass is less than 60 μm. The chemically strengthened glass of claim 1, wherein in the first step of ion exchange of the alkali metal aluminosilicate glass, the alkali metal aluminosilicate glass is immersed in 5-95 wt % NaNO ₃ and 5-95 wt% _KNO3 in a salt bath. The chemically strengthened glass of claim 7, wherein in the first step of ion exchange of the alkali metal aluminosilicate glass, the alkali metal aluminosilicate glass is immersed in the salt bath at a temperature greater than 300°C. The chemically strengthened glass of claim 7, wherein in the first step of ion exchange of the alkali metal aluminosilicate glass, the alkali metal aluminosilicate glass is immersed in the salt bath for a duration of at least 0.25 hours. The chemically strengthened glass of claim 1, wherein in the second step of ion exchange of the alkali metal aluminosilicate glass, the alkali metal aluminosilicate glass is immersed in 0-50% by weight NaNO ₃ and 50- 100 wt% _KNO3 in a salt bath. The chemically strengthened glass of claim 10, wherein in the second step of ion exchange of the alkali metal aluminosilicate glass, the alkali metal aluminosilicate glass is immersed in the salt bath at a temperature greater than 300°C. The chemically strengthened glass of claim 10, wherein in the second step of ion exchange of the alkali metal aluminosilicate glass, the alkali metal aluminosilicate glass is immersed in the salt bath for a duration of 0.1 to 6.5 hours middle. The chemically strengthened glass of claim 1, wherein the chemically strengthened glass has the following composition: 50 mol % to 75 mol % SiO ₂ ; 5 mol % to 25 mol % Al ₂ O ₃ ; 0 mol % % to 10 mol% of B ₂ O ₃ ; 0 to 15 mol % of Na ₂ O; 5 to 17 mol % of Li ₂ O; 0 to 2 mol % 0 to 7 mol% of MgO; ₀ to 3 mol% of CaO; 0 to 7 mol% of ZnO; 0 to 7 mol% of ZrO ₂ ; 0 mol % to 2.5 mol % Fe ₂ O ₃ ; 0 mol % to 2 mol % TiO ₂ ; 0 mol % to 2 mol % CeO ₂ ; 0 mol % to 7 mol % of P ₂ O ₅ ; and 0 to 2.5 mol % of SnO ₂ . As claimed in the chemically strengthened glass of claim 1, the CS-DOL distribution comprises: a third straight line a _{3 extending from a linear point (DOL_Linear, CS_Linear) to the point of maximum compressive stress; from the third straight line a 3 at} the linear point The angle E formed with respect to the axis of the DOL, wherein the angle E is defined by the following expression: E = Arc Tangent ((CS-CS_Linear)/(DOL_Linear)); and from the point extending from the point of inflection to the point of maximum compressive stress The angle F formed by the second straight line a ₂₂ at the inflection point with respect to the axis of the DOL, and where the angle F is defined by the following expression: F=Arc Tangent ((CS - CS_TP)/(DOL_TP)), where the The range of the equal angles E and F is defined by the following expression: |(E/F) -(EF)|^0.5 ≦ 4, wherein the range of the equal angles E and F is the same as the double angle of the alkali metal aluminosilicate glass. The processing time of the ion exchange process is proportional.

Images