Glass substrate, chemically strengthened glass and method for strengthening thereof, cover glass

Abstract

The application relates to the technical field of special glass, and provides a glass substrate, chemically strengthened glass and a strengthening method and cover plate glass. The glass substrate provided by the application comprises the following components in terms of the total mole content of oxides in the glass substrate: SiO2: 58-68%; Al2O3: 7.5-9.2%; Na2O: 11.3-14.5%; K2O: 2.5-5%; MgO: 7.5-10.2%; B2O3: 0-2%; ZnO: 0.1-2%; and WO3: 0.1-4%. The size change rate of the glass substrate provided by the application is less than or equal to 0.015% before and after chemical strengthening. During the chemical strengthening process, the glass substrate needs to be inserted into a holder, and then the glass substrate and the holder are placed in a strengthening salt bath for strengthening. Since the size change rate of the glass substrate provided by the application is small, the holder does not need to reserve a large size change gap, and the risk of glass film falling can be obviously reduced.

Description

Technical Field

[0001] This application belongs to the field of special glass technology, and in particular relates to a glass substrate, chemically strengthened glass and its strengthening method, and cover glass. Background Technology

[0002] Chemically strengthened glass is widely used in electronic devices as covers or windows for portable or handheld electronic communication and entertainment devices, such as mobile phones, smartphones, tablets, video players, information terminal (IT) devices, and tablet computers, as well as other applications. The most widely used method of chemical strengthening is ion exchange. Ion-exchanged glass possesses high strength and excellent damage resistance, and is widely used in flat panel displays, heat-resistant fireplace windows, micro-optical components, aircraft cockpits, and high-speed train windshields. Ion exchange typically involves the replacement of smaller ions with larger ions, creating surface stress on the glass surface to enhance its strength and damage resistance.

[0003] The basic principle of chemically strengthened glass is to form a compression layer on the glass surface through ion exchange. This compression layer can resist external impacts and pressures, thereby increasing the strength and durability of the glass. The main chemical substances used in this process are sodium and potassium ions. The glass product is immersed in a salt solution containing sodium or potassium ions. The sodium or potassium ions in this solution exchange ions with those on the glass surface. Due to the high concentration of sodium or potassium ions in the salt solution, they replace the sodium or potassium ions on the glass surface and penetrate into the glass. During the ion exchange process, because sodium or potassium ions are relatively large, their entry into the glass creates a certain compressive stress. This compressive stress causes the formation of a compression layer on the glass surface, thereby increasing the strength and impact resistance of the glass. Simultaneously, the presence of the compression layer can also prevent crack propagation and improve the fracture toughness of the glass.

[0004] Low-temperature ion exchange involves immersing glass in molten salt. Under specific strengthening temperatures and times, large-radius ions (such as K+) in the molten salt are released into the glass. + ), to remove small-radius ions (e.g., Na+) from the glass. + The replacement of smaller ions with larger ions causes a "squeezing" expansion on the glass surface, generating compressive stress. Because larger ions replace smaller ions, the dimensions of the strengthened glass change, thus reducing the yield rate of the processed product. Summary of the Invention

[0005] The purpose of this application is to provide a glass substrate, chemically strengthened glass and its strengthening method, and a cover glass, which aims to solve the problem of large dimensional change rate of glass substrates after chemical strengthening.

[0006] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows:

[0007] In a first aspect, this application provides a glass substrate comprising, based on a total molar amount of oxides in the glass substrate of 100%, the following components in molar percentage:

[0008] SiO2: 58-68%;

[0009] Al2O3: 7.5–9.2%;

[0010] Na₂O: 11.3–14.5%;

[0011] K2O: 2.5-5%;

[0012] MgO: 7.5–10.2%;

[0013] B2O3: 0-2%;

[0014] ZnO: 0.1-2%;

[0015] WO3: 0.1%–4%.

[0016] Secondly, this application provides a chemically strengthened glass, which is obtained by ion exchange of the glass substrate described in the first aspect.

[0017] Thirdly, this application provides a method for strengthening chemically strengthened glass, comprising the following steps: strengthening the glass substrate described in the first aspect in a monovalent metal nitrate molten salt to obtain the chemically strengthened glass.

[0018] Fourthly, this application provides a cover glass, including chemically strengthened glass as described in the second aspect or chemically strengthened glass obtained by the strengthening method described in the third aspect.

[0019] The glass substrate provided in the first aspect of this application has a dimensional change rate of ≤0.015% before and after chemical strengthening. During the chemical strengthening process, the glass substrate needs to be inserted into a holder, and then the glass substrate and the holder are placed in a strengthening salt bath for strengthening. Since the dimensional change rate of the glass substrate provided in this application is small, the holder does not need to reserve a large dimensional change gap, which can significantly reduce the risk of glass flipping.

[0020] The chemically strengthened glass provided in the second aspect of this application is made from the glass substrate described in the first aspect through ion exchange. Therefore, the chemically strengthened glass not only has a small dimensional change rate, but also has high strength and excellent damage resistance.

[0021] The strengthening method for chemically strengthened glass provided in the third aspect of this application, by employing the glass substrate of the first aspect and the strengthening method itself, can significantly reduce edge chipping and cracking problems generated during chemical strengthening, greatly improving product processing yield, and is particularly suitable for the production of cover glass substrates. Furthermore, this application uses a potassium nitrate content of ≥95% by mass in the chemical strengthening molten salt, effectively avoiding the problems of slow ion exchange efficiency and low surface compressive stress during the strengthening process. Using an ion exchange temperature ≤450℃ effectively avoids the problem of excessive shrinkage of the glass after heating and then cooling.

[0022] The fourth aspect of this application provides a cover glass that, due to the use of chemically strengthened glass as described in the second aspect or chemically strengthened glass prepared by the strengthening method described in the third aspect, has good glass strength and damage resistance. Detailed Implementation

[0023] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0024] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0025] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0026] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0027] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0028] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a mass unit known in the chemical industry, such as μg, mg, g, or kg.

[0029] The terms "first" and "second" are used for descriptive purposes only, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. For example, without departing from the scope of the embodiments of this application, "first XX" may also be referred to as "second XX," and similarly, "second XX" may also be referred to as "first XX." Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0030] The first aspect of this application provides a glass substrate comprising, based on the total molar amount of oxides in the glass substrate as 100%, the following components in molar percentage: SiO2: 58-68%; Al2O3: 7.5-9.2%; Na2O: 11.3-14.5%; K2O: 2.5-5%; MgO: 7.5-10.2%; B2O3: 0-2%; ZnO: 0.1-2%; WO3: 0.1-4%.

[0031] SiO2 is a glass network forgiving material. It can reduce the coefficient of thermal expansion of glass and improve its thermal stability, chemical stability, hardness, and mechanical strength. Excessive SiO2 content can lead to difficulties in glass melting, reduced meltability, and increased crystallization; conversely, insufficient SiO2 content can cause devitrification or reduced weather resistance. Therefore, the preferred molar percentage content of SiO2 in this application is 58% to 68%.

[0032] Al₂O₃ in glass can improve its chemical stability, thermal stability, mechanical strength, and hardness. Furthermore, because the interfacial spaces between aluminum-oxygen tetrahedra are larger than those between silicon-oxygen tetrahedra, Al₂O₃ imparts a larger compressive stress layer and higher strengthening efficiency to the glass. However, if the Al₂O₃ content is too high, the viscosity and devitrification temperature of the glass increase, and its meltability decreases. Therefore, in this application, the molar percentage content of Al₂O₃ is preferably 7.5% to 9.2%, more preferably 8% to 9%.

[0033] Na₂O is an ion-exchange component and is responsible for reducing high-temperature viscosity and improving melt flowability and formability. However, Na₂O increases the coefficient of thermal expansion of glass and reduces its chemical stability and mechanical strength. Therefore, the amount of Na₂O in this application should not be excessive, and the preferred molar percentage content of Na₂O is 11.3% to 14.5%.

[0034] K₂O in glass can reduce high-temperature viscosity, improve melt flowability and formability, and is also a component that increases Vickers hardness and inhibits devitrification. However, if the K₂O content is too high, the glass cannot achieve the desired surface compressive stress after chemical strengthening. Therefore, the preferred molar percentage content of K₂O in this application is 2.5% to 5%.

[0035] MgO is an exooxide with a glass network structure. MgO can lower the melting point of glass, improve the homogeneity of molten glass, enhance glass melt properties, increase hydrolysis resistance, and improve glass durability. However, the addition of MgO tends to reduce the ion exchange performance of the product, adversely affecting the compressive stress depth of the product. Therefore, the molar percentage content of MgO in this application is preferably 7.5% to 10.2%, more preferably 8% to 9%.

[0036] B₂O₃ is a forging oxide that can reduce the coefficient of thermal expansion of aluminosilicate glass, improve its thermal and chemical stability, and also has a fluxing effect. However, when the amount of B₂O₃ introduced is too high, the coefficient of thermal expansion of boroaluminosilicate glass increases due to the increase of boron-oxygen trigonal [BO₃], resulting in an abnormal phenomenon, and it also inhibits chemical strengthening. Therefore, the molar percentage content of B₂O₃ in this application is preferably 0.1% to 2%, and more preferably...

[0037] ZnO in high alkali metal oxide silicate glass, Zn 2+ The glass exists in both six-coordinate [ZnO6] and four-coordinate [ZnO4] states. The six-coordinate [ZnO6] structure is more compact, while the four-coordinate [ZnO4] structure is more porous. The number of four-coordinate atoms increases with the alkali metal oxide content. When the content of four-coordinate [ZnO4] is higher, the glass network is more porous, which is conducive to the presence of sodium ions (Na+) in the glass. +The ZnO content plays a positive role in improving the ion exchange efficiency, exchange depth, and surface strength of glass. However, excessively high ZnO concentrations tend to form zinc spinel (ZnAl2O4) or zinc silicate (Zn2SiO4), leading to excessive phase separation in the glass. Therefore, in this application, the molar percentage content of ZnO is preferably 0.1% to 2%, more preferably 0.5% to 1.5%.

[0038] WO3 is an intermediate oxide and generally cannot form glass on its own. In glass networks, it exists in two coordination modes: [WO4] and [WO6]. Normally, the coordination number of tungsten ions is 6, but it can become 4 after abstracting free oxygen. When WO3 exists as [WO4], it participates in the formation of the glass network, playing a supporting role and facilitating the formation of Na+. + Migration increases the depth of the glass ion exchange layer. However, excessive WO3 content will make glass melting difficult. In this application, the molar percentage content of WO3 is preferably 0.1% to 4%, more preferably 1.5% to 2.5%.

[0039] The glass substrate provided in the first aspect of this application has a dimensional change rate of ≤0.015% before and after chemical strengthening. During the chemical strengthening process, the glass substrate needs to be inserted into a holder, and then the glass substrate and the holder are placed in a strengthening salt bath for strengthening. Since the dimensional change rate of the glass substrate provided in this application is small, the holder does not need to reserve a large dimensional change gap, which can significantly reduce the risk of glass meltdown.

[0040] In some embodiments, X1 is defined as ([Na2O]+[K2O]+[MgO]) / (2[ZnO]+[B2O3]+[Al2O3]+[WO3]), 1.5≤X1≤3.5, where [Na2O] is the molar percentage of Na2O, [K2O] is the molar percentage of K2O, [Al2O3] is the molar percentage of Al2O3, [MgO] is the molar percentage of MgO, [ZnO] is the molar percentage of ZnO, [B2O3] is the molar percentage of B2O3, and [WO3] is the molar percentage of WO3.

[0041] In glass substrates, components such as Na₂O, K₂O, and MgO provide free oxygen. The inventors discovered that by controlling X₁ within the range of 1.5 to 3.5, sufficient free oxygen can be present in the network to promote Al₂O₃ production. 3+ B 3+ W 6+ and Zn 2+ It mainly exists in the states of [AlO4], [BO4], [WO4] and [ZnO4]. 3+ B3+ W 6+ and Zn 2+ When it exists as a tetracoordinate, it can participate in the formation of the glass network, playing a supporting role in the glass network, which is conducive to Na+ migration and thus increases the depth of the glass ion exchange layer.

[0042] In some embodiments, based on the total molar amount of oxides in the glass substrate being 100%, the component further includes the following molar percentage: ZrO2: 0.2% to 0.5%.

[0043] ZrO2 is a common nucleating agent and can participate in the network structure of glass in the form of [ZrO4] tetrahedra and [ZrO6] octahedra, thereby improving the strain point, mechanical strength, stability, and alkali resistance of the glass. ZrO2 promotes the movement of sodium ions in the glass and increases the surface compressive stress after chemical strengthening. However, excessive ZrO2 content can lead to problems such as crystallization, melting difficulties, and excessively high forming temperatures. Therefore, the molar percentage content of ZrO2 in this application is preferably 0.2% to 0.5%.

[0044] In some embodiments, X2 is defined as ([Na2O]+[K2O]+[MgO]+[B2O3]) / ([WO3]+[ZrO2]+0.5[Al2O3]), 3≤X2≤6.5, and more preferably 3.5≤X2≤5, where [ZrO2] is the molar percentage content of ZrO2.

[0045] Among the various components of the glass substrate, Na2O, K2O, MgO, and B2O3 all have a fluxing effect, which can lower the melting temperature. Increasing the content of WO3, ZrO2, and Al2O3 can increase the melting temperature and the elastic modulus of the network structure. The inventors discovered through research that by controlling X2 within the range of 3 to 6.5, the elastic modulus of the network structure can be effectively improved without causing the glass melting temperature to be too high.

[0046] In some embodiments, X3 is defined as ([WO3]+1.5[B2O3]+3[ZrO2]+[Al2O3]+[ZnO]) / (0.5[B2O3]+0.5[ZnO]), where 9≤X3≤50, and more preferably 10≤X3≤25.

[0047] Among the components of the glass substrate, ZrO2 and Al2O3 can improve the elastic modulus of the network structure; W 6+When present in the form of [WO4], it participates in the formation of the glass network, playing a supporting role and increasing the elastic modulus of the network structure. B2O3, on the one hand, increases the elastic modulus of the network structure; on the other hand, the formed [BO4] coordination enhances the compactness of the network structure, hindering ion migration and thus ion exchange. The tetracoordinate [ZnO4] structure formed by ZnO is relatively loose, which is beneficial for ion exchange but detrimental to the elastic modulus of the network structure. The inventors discovered through research that by controlling X3 within the range of 9–50, it is possible to both promote ion exchange and increase the elastic modulus of the network structure.

[0048] In some embodiments, X4 is defined as (2[Na2O]+3[K2O]+2[Al2O3]) / 3[MgO], where 1.5≤X4≤2.6. By controlling X1, X2, and X3 within the above ranges, and further controlling X4 within the range of 1.5 to 2.6, the composition of the glass substrate can be optimized, thereby reducing the dimensional change rate of the glass substrate after strengthening and improving the product processing yield.

[0049] In some embodiments, the thickness of the glass substrate is 0.1 to 5 mm.

[0050] The glass substrates of this application are applicable to various glass manufacturing processes, without strictly limiting the manufacturing process. A suitable manufacturing process can be selected according to actual application needs, making it widely applicable and flexible in application. Methods for melting various raw material components to form glass include, but are not limited to, at least one of the following: float glass, overflow glass, upward drawing glass, rolling glass, flat drawing glass, and molding glass. Preferably, the float glass process is used, in which the glass raw material components are mixed and then sequentially subjected to melting, clarification, homogenization, shaping, and annealing processes to prepare the glass substrate.

[0051] The second aspect of this application provides a chemically strengthened glass, which is obtained by ion exchange from the glass substrate of the first aspect.

[0052] The chemically strengthened glass provided in the second aspect of this application is made from the glass substrate described in the first aspect through ion exchange. Therefore, the chemically strengthened glass not only has a small dimensional change rate, but also has high strength and excellent damage resistance.

[0053] In some embodiments, the surface compressive stress of the chemically strengthened glass is ≥700 MPa, more preferably ≥720 MPa. In some embodiments, the ion exchange depth of the chemically strengthened glass is ≥17 μm.

[0054] The third aspect of this application provides a method for strengthening chemically strengthened glass, comprising the following steps: placing a glass substrate from the first aspect into a monovalent metal nitrate molten salt for strengthening treatment to obtain chemically strengthened glass.

[0055] The strengthening method for chemically strengthened glass provided in the third aspect of this application, by adopting the glass substrate of the first aspect and the strengthening method therein, can significantly reduce edge chipping and cracking problems that occur during chemical strengthening, greatly improving the product processing yield, and is particularly suitable for the production of cover glass substrates.

[0056] In some embodiments, the monovalent metal nitrate molten salt can be a pure potassium nitrate molten salt or a mixed molten salt of potassium nitrate and sodium nitrate. When it is a mixed molten salt, the mass percentage of potassium nitrate in the monovalent metal nitrate molten salt is ≥95%, and the mass percentage of sodium nitrate in the monovalent metal nitrate molten salt is ≤5%. Potassium nitrate provides K in the mixed molten salt. + K + Sufficient amount is needed to meet the requirements of Na in the glass during the chemical strengthening process. + Rapid exchange.

[0057] In some embodiments, the strengthening treatment step involves a strengthening treatment temperature ≤450℃ and a strengthening treatment time ≤5h. The inventors discovered through research that using a potassium nitrate molar percentage content ≥95% in the chemically strengthened molten salt effectively avoids the problems of slow ion exchange efficiency and low surface compressive stress during the strengthening process.

[0058] Furthermore, the strengthening treatment temperature is 390–410℃, and the strengthening treatment time is 3.5–4.5 hours. More preferably, the strengthening treatment temperature is 400℃, and the strengthening treatment time is 4 hours. The inventors discovered through research that using an ion exchange temperature ≤450℃ effectively avoids the problem of excessive shrinkage of the glass after heating and then cooling.

[0059] The fourth aspect of this application provides a cover glass, including the chemically strengthened glass of the second aspect or the chemically strengthened glass obtained by the strengthening method of the third aspect.

[0060] The fourth aspect of this application provides a cover glass that, due to the use of chemically strengthened glass as described in the second aspect or chemically strengthened glass prepared by the strengthening method described in the third aspect, has good glass strength and damage resistance.

[0061] The following description is based on specific embodiments.

[0062] Example 1

[0063] This embodiment provides a glass substrate and its preparation method.

[0064] A glass substrate comprising, by molar percentage of oxides: SiO2: 67%; Al2O3: 7.6%; Na2O: 11.3%; K2O: 2.6%; MgO: 10%; ZnO: 0.4%; ZrO2: 0.5%; B2O3: 0.1%; WO3: 0.5%.

[0065] A method for preparing a glass substrate includes the following steps:

[0066] S1: Weigh each component according to the formula;

[0067] S2: After mixing the components, heat the mixture from room temperature to 1400℃ at a heating rate of 10℃ / min, hold for 150min, then heat the mixture from 1400℃ to 1650℃ at a heating rate of 6℃ / min, hold for 360min, clarify and homogenize to obtain glass melt.

[0068] S3: Pour the molten glass into a mold for shaping, cool until the glass solidifies, and then transfer it to a muffle furnace for heat preservation and annealing to obtain glass;

[0069] S4: The glass is cut, ground and polished to obtain a glass substrate with a thickness of 0.7mm.

[0070] Example 2

[0071] This embodiment provides a glass substrate and its preparation method.

[0072] A glass substrate, comprising the following components by molar percentage of oxides: SiO2: 65%; Al2O3: 8.0%; Na2O: 14%; K2O: 2.9%; MgO: 8%; ZnO: 0.4%; ZrO2: 0.2%; B2O3: 0.5%; WO3: 1%. The preparation method of Example 2 is the same as that of Example 1.

[0073] Example 3

[0074] This embodiment provides a glass substrate and its preparation method.

[0075] A glass substrate, comprising the following components by molar percentage of oxides: SiO2: 63%; Al2O3: 8.0%; Na2O: 12.6%; K2O: 4%; MgO: 8.5%; ZnO: 0.7%; ZrO2: 0.2%; B2O3: 1%; WO3: 2%. The preparation method of Example 3 is the same as that of Example 1.

[0076] Example 4

[0077] This embodiment provides a glass substrate and its preparation method.

[0078] A glass substrate, comprising the following components by molar percentage of oxides: SiO2: 61%; Al2O3: 8.4%; Na2O: 13%; K2O: 5%; MgO: 8.3%; ZnO: 1%; ZrO2: 0.2%; B2O3: 0.1%; WO3: 3%. The preparation method of Example 4 is the same as that of Example 1.

[0079] Example 5

[0080] This embodiment provides a glass substrate and its preparation method.

[0081] A glass substrate, comprising the following components by molar percentage of oxides: SiO2: 60%; Al2O3: 8.8%; Na2O: 14.5%; K2O: 3.7%; MgO: 7.5%; ZnO: 1.5%; ZrO2: 0.5%; B2O3: 1.5%; WO3: 2%. The preparation method of Example 5 is the same as that of Example 1.

[0082] Example 6

[0083] This embodiment provides a glass substrate and its preparation method.

[0084] A glass substrate, comprising the following components in molar percentage of oxides: SiO2: 58%; Al2O3: 9%; Na2O: 13%; K2O: 3%; MgO: 8%; ZnO: 2%; ZrO2: 1%; B2O3: 2%; WO3: 4%. The preparation method of Example 6 is the same as that of Example 1.

[0085] Comparative Example 1

[0086] A glass substrate comprising, by molar percentage of oxides: SiO2: 72%; Al2O3: 5%; Na2O: 16%; K2O: 3%; MgO: 2.5%; ZrO2: 0.2%; B2O3: 1.3%.

[0087] The preparation method of Comparative Example 1 is the same as that of Example 1.

[0088] Comparative Example 2

[0089] A glass substrate comprising, by molar percentage of oxides: SiO2: 68%; Al2O3: 10%; Na2O: 14%; K2O: 5%; MgO: 2.5%; ZrO2: 0.5%.

[0090] The preparation method of Comparative Example 1 is the same as that of Example 1.

[0091] Examples 1 to 6 and Comparative Examples 1 and 2

[0092] A glass substrate having the composition shown in Table 1 is provided, the glass substrate having a thickness of 0.7 mm.

[0093] Table 1

[0094]

[0095] The glass (Tg) point temperature of the glass substrates in Examples 1 to 6 and Comparative Examples 1 and 2 were tested respectively. The results are shown in Table 2. The glass (Tg) point temperature and thermal shrinkage rate mentioned in this application were obtained using industry-standard methods. The glass Tg point was tested using the ASTM E-228 method.

[0096] The basic properties of the glass substrates provided in Examples 1 to 6 and Comparative Examples 1 and 2 are shown in Table 2.

[0097] Table 2

[0098]

[0099] Examples 1a to 6a and Comparative Examples 1a and 2a

[0100] The glass substrates in Examples 1 to 6 were chemically strengthened using an ion exchange process to obtain chemically strengthened glasses for Examples 1a to 6a, and Comparative Examples 1a and 2a, respectively.

[0101] The chemical strengthening process is as follows: The glass substrate is immersed in a strengthening molten salt bath for treatment. The molten salt contains 98% potassium nitrate and 2000 ppm sodium ions. The chemical strengthening temperature is 400℃, and the chemical strengthening time is 4 hours.

[0102] Performance testing

[0103] The surface compressive stress (CS), ion exchange depth (DOL), and dimensional change rate of the chemically strengthened glass in Examples 1a to 6a, and Comparative Examples 1a and 2a were tested respectively.

[0104] Surface compressive stress: After chemical strengthening, the larger ions in the molten salt displace the smaller ions in the glass, causing a "clogging" effect on the glass surface. This results in compressive stress on the glass surface, known as surface compressive stress. Measurement method for surface compressive stress (CS): Measured using an optical waveguide surface stress meter (Orihara Surface Stress Meter, FSM6000Le).

[0105] Ion exchange depth (DOL): This represents the depth of exchange between potassium and sodium ions. The ion exchange depth is measured using an Orihara Surface Stress Meter (FSM6000Le).

[0106] The basic properties of the chemically strengthened glasses provided in Examples 1a to 6a and Comparative Examples 1a and 2a are shown in Table 3.

[0107] Table 3

[0108]

[0109] Combining the data in Tables 1 and 2, it can be seen that the glass transition temperature of the glass substrates in Examples 1 to 6 of this application is significantly lower than that in Comparative Examples 1 and 2. According to the data in Table 3, the chemically strengthened glass in Examples 1a to 6a has a dimensional change rate of less than 0.015% before and after chemical strengthening, and a surface compressive stress value of greater than 700 MPa.

[0110] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A glass substrate, characterized in that, Based on the total molar amount of oxides in the glass substrate being 100%, the components include the following molar percentages: SiO2: 58~68%; Al2O3: 7.5~9.2%; Na₂O: 11.3~14.5%; K2O: 2.5~5%; MgO: 7.5~10.2%; B2O3: 0~2%; ZnO: 0.1~2%; WO3: 2~4%; ZrO2: 0.2%~0.5%; Define X1 = ([Na2O] + [K2O] + [MgO]) / (2[ZnO] + [B2O3] + [Al2O3] + [WO3]), 1.5 ≤ X1 ≤ 3.5, where [Na2O] is the molar percentage of Na2O, [K2O] is the molar percentage of K2O, [Al2O3] is the molar percentage of Al2O3, [MgO] is the molar percentage of MgO, [ZnO] is the molar percentage of ZnO, [B2O3] is the molar percentage of B2O3, and [WO3] is the molar percentage of WO3. Define X2 = ([Na2O] + [K2O] + [MgO] + [B2O3]) / ([WO3] + [ZrO2] + 0.5[Al2O3]), 3.5 ≤ X2 ≤ 5, where [ZrO2] is the molar percentage content of ZrO2; The dimensional change rate of the glass substrate before and after chemical strengthening is ≤0.015%.

2. The glass substrate as described in claim 1, characterized in that, Define X3=([WO3]+1.5[B2O3]+3[ZrO2]+[Al2O3]+[ZnO]) / (0.5[B2O3]+0.5[ZnO]), 9≤X3≤50.

3. The glass substrate as described in claim 2, characterized in that, Define X4 = (2[Na2O] + 3[K2O] + 2[Al2O3]) / 3[MgO], 1.5 ≤ X4 ≤ 2.6; and / or, The thickness of the glass substrate is 0.1~5mm.

4. A chemically strengthened glass, characterized in that, The chemically strengthened glass is prepared by ion exchange of the glass substrate described in any one of claims 1 to 3; The glass substrate exhibits a dimensional change rate ≤ 0.015% before and after chemical strengthening.

5. The chemically strengthened glass as described in claim 4, characterized in that, The surface compressive stress of the chemically strengthened glass is ≥700MPa; and / or, The ion exchange depth of the chemically strengthened glass is ≥17μm.

6. A method for strengthening chemically strengthened glass, characterized in that, The process includes the following steps: placing the glass substrate according to any one of claims 1 to 3 into a monovalent metal nitrate molten salt for strengthening treatment to obtain the chemically strengthened glass; The glass substrate exhibits a dimensional change rate ≤ 0.015% before and after chemical strengthening.

7. A cover glass, characterized in that, This includes chemically strengthened glass as described in claim 4 or 5, or chemically strengthened glass prepared by the strengthening method described in claim 6.

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