Chemical strengthening method of glass, chemically strengthened glass and application of chemically strengthened glass

Abstract

The invention provides a chemical strengthening method of glass, chemically strengthened glass and application of the chemically strengthened glass, and belongs to the technical field of glass strengthening. According to the chemical strengthening method of the glass, a certain amount of alkali metal ions contained in the glass are added into first fused salt, and the condition of first ion exchange treatment is adjusted, so that the ion exchange capacity is reduced under the condition of guaranteeing the depth of an ion exchange layer; by controlling the content of KNO3 in the second molten salt and the conditions of the second ion exchange treatment, the second molten salt contains more alkali metal ions needing to be exchanged, so that the pressure stress of the glass surface meets the requirement in a short time, the overall ion exchange capacity is reduced, and the service life of the glass is prolonged. The chemically strengthened glass prepared by the invention has low expansion size and high pressure stress, and meets the requirements of the chemically strengthened glass on the expansion size and the pressure stress.

Description

Technical Field

[0001] This application relates to the field of glass strengthening technology, and in particular to chemical strengthening methods for glass, chemically strengthened glass, and their applications. Background Technology

[0002] In the selection of cover materials for electronic devices (especially displays and touch interfaces), glass is the preferred choice due to its excellent optical transmittance and high surface hardness. Ion exchange chemical strengthening processes are typically used to further improve the mechanical properties of the glass substrate (such as impact resistance, scratch resistance, and flexural strength) and ensure a fragment passivation effect in the event of failure (preventing the formation of sharp, dangerous fragments). However, this process usually results in a certain degree of expansion in the glass. Excessive expansion and differences in local expansion coefficients can lead to glass cracking or warping, affecting its application in electronic devices.

[0003] Therefore, how to improve the chemical strengthening process of glass in order to improve the expansion dimensions and compressive stress of the chemically strengthened glass has become an urgent technical problem to be solved. Summary of the Invention

[0004] Based on this, the main objective of this application is to provide a chemical strengthening method for glass, chemically strengthened glass and its applications, so as to improve the coefficient of thermal expansion of chemically strengthened glass and also to provide high-pressure stress performance.

[0005] The first aspect of this application provides a method for chemically strengthening glass, comprising the following steps:

[0006] Chemically strengthened glass is prepared by immersing the glass in a first molten salt for a first ion exchange treatment, and then immersing it in a second molten salt for a second ion exchange treatment.

[0007] The first molten salt comprises 75%-99% by mass of KNO3 and 1%-25% by mass of a first alkali metal salt; the first alkali metal in the first alkali metal salt is an alkali metal ion in the glass.

[0008] The conditions for the first ion exchange treatment included: a temperature of 405-440℃ and a time of 10-420 min.

[0009] The second molten salt comprises 90%-100% by mass of KNO3;

[0010] The conditions for the second ion exchange treatment include: a temperature of 380-420℃ and a time of 10-60 min.

[0011] In some embodiments, the first alkali metal salt includes NaNO3 and / or LiNO3.

[0012] In some embodiments, the second molten salt further includes NaNO3.

[0013] In some embodiments, before immersing the glass in the first molten salt for the first ion exchange treatment, a step of preheating the glass is included, wherein the preheating conditions include: a temperature of 350-380°C and a time of 10-40 minutes.

[0014] In some embodiments, the glass is aluminosilicate glass.

[0015] In some embodiments, the aluminosilicate glass is lithium aluminosilicate glass or sodium aluminosilicate glass.

[0016] In some embodiments, the aluminosilicate glass is sodium aluminum silicate glass;

[0017] The first molten salt comprises the following components by mass fraction: 1%-25% NaNO3 and 75%-99% KNO3;

[0018] The conditions for the first ion exchange treatment included: a temperature of 420-440℃ and a time of 300-420 min.

[0019] The second molten salt is KNO3;

[0020] The conditions for the second ion exchange treatment include: a temperature of 400-440℃ and a time of 10-60 min.

[0021] In some embodiments, the aluminosilicate glass is lithium aluminosilicate glass;

[0022] The first molten salt comprises the following components by mass fraction: 2%-15% LiNO3 and 85%-98% KNO3;

[0023] The conditions for the first ion exchange treatment include: temperature of 380-440℃; time of 10-75 min.

[0024] The second molten salt comprises the following components by mass fraction: 0%-10% NaNO3 and 90%-100% KNO3;

[0025] The conditions for the second ion exchange treatment include: a temperature of 380-440℃ and a time of 30-60 min.

[0026] In a second aspect, this application provides a chemically strengthened glass prepared by the chemical strengthening method for glass described in the first aspect.

[0027] In some embodiments, the coefficient of thermal expansion of the chemically strengthened glass is 0.010%-0.052%.

[0028] The third aspect of this application provides the application of chemically strengthened glass prepared by the chemical strengthening method of the glass described in the first aspect or the chemically strengthened glass described in the second aspect as a glass cover for electronic devices.

[0029] Compared with traditional technologies, this application has at least the following beneficial effects:

[0030] This application prepares chemically strengthened glass by controlling the composition of the first and second molten salts and the conditions of the first and second ion exchange treatments. This significantly reduces the expansion dimensions of the chemically strengthened glass, further reducing warping and cracking. Simultaneously, the chemically strengthened glass meets the requirements of high-pressure stress, has a short preparation cycle, and high production efficiency, making it a promising candidate for electronic device cover glass. Specifically, by adding a certain amount of alkali metal ions present in the glass to the first molten salt and adjusting the conditions of the first ion exchange treatment, the ion exchange volume is reduced while ensuring the depth of the ion exchange layer. Then, by controlling the KNO3 content in the second molten salt and the conditions of the second ion exchange treatment, the second molten salt contains a larger amount of the alkali metal ions to be exchanged, allowing the compressive stress on the glass surface to meet the requirements in a shorter time, thereby reducing the overall ion exchange volume and thus reducing the expansion dimensions. Detailed Implementation

[0031] The present application will be further described in detail below with reference to the embodiments and examples. These embodiments and examples are for illustrative purposes only and are not intended to limit the scope of the present application. The purpose of providing these embodiments and examples is to enable a more thorough and comprehensive understanding of the disclosure of the present application. It should also be understood that the present application can be implemented in many different forms and is not limited to the embodiments and examples described herein. Those skilled in the art can make various modifications or alterations without departing from the spirit of the present application, and the equivalent forms obtained also fall within the protection scope of the present application. Furthermore, numerous specific details are set forth in the following description to provide a fuller understanding of the present application. It should be understood that the present application can be implemented without one or more of these details.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0033] To address the problem of excessive glass expansion caused by traditional ion-exchange chemical strengthening processes, this application prepares chemically strengthened glass by controlling the composition of the first and second molten salts, as well as the conditions of the first and second ion-exchange treatments. This significantly reduces the expansion size of the chemically strengthened glass, further minimizing warping and cracking. Simultaneously, the chemically strengthened glass meets the requirements of high-pressure stress, has a short preparation cycle, and high production efficiency, making it a promising candidate for electronic device cover glass. Specifically, by adding a certain amount of alkali metal ions present in the glass to the first molten salt and adjusting the conditions of the first ion-exchange treatment, the ion exchange volume is reduced while maintaining the depth of the ion exchange layer. Then, by controlling the KNO3 content in the second molten salt and the conditions of the second ion-exchange treatment, the second molten salt contains a higher concentration of the required alkali metal ions, enabling the compressive stress on the glass surface to meet the requirements in a shorter time, thereby reducing the overall ion exchange volume and consequently reducing the expansion size.

[0034] The first aspect of this application provides a method for chemically strengthening glass, comprising the following steps:

[0035] Chemically strengthened glass is prepared by immersing the glass in a first molten salt for a first ion exchange treatment, and then immersing it in a second molten salt for a second ion exchange treatment.

[0036] The first molten salt comprises 75%-99% by mass of KNO3 and 1%-25% by mass of a first alkali metal salt; the first alkali metal in the first alkali metal salt is an alkali metal ion in the glass.

[0037] The conditions for the first ion exchange treatment included: a temperature of 405-440℃ and a time of 10-420 min.

[0038] The second molten salt comprises 90%-100% by mass of KNO3;

[0039] The conditions for the second ion exchange treatment include: a temperature of 380-420℃ and a time of 10-60 min.

[0040] This application reduces the amount of ion exchange while ensuring the depth of the ion exchange layer by adding a certain amount of alkali metal ions contained in the glass to the first molten salt and adjusting the conditions of the first ion exchange treatment. Then, by controlling the content of KNO3 in the second molten salt and the conditions of the second ion exchange treatment, the second molten salt contains more alkali metal ions that need to be exchanged, so that the compressive stress on the glass surface meets the requirements in a shorter time, thereby reducing the overall amount of ion exchange and thus reducing the expansion size.

[0041] In some embodiments, the first alkali metal salt includes NaNO3 and / or LiNO3.

[0042] In some embodiments, the first molten salt comprises: 75%-99% by mass of KNO3 and 1%-25% by mass of NaNO3; wherein the mass fraction of KNO3 in the first molten salt can be 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98% or 99%; and the mass fraction of NaNO3 can be 1%, 2%, 3%, 4%, 5%, 10%, 15%, 20% or 25%.

[0043] In some embodiments, the first molten salt comprises: 75%-99% by mass of KNO3 and 1%-25% by mass of LiNO3; wherein the mass fraction of KNO3 in the first molten salt can be 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98% or 99%; and the mass fraction of LiNO3 can be 1%, 2%, 3%, 4%, 5%, 10%, 15%, 20% or 25%.

[0044] In some embodiments, the second molten salt further includes NaNO3.

[0045] In some embodiments, the second molten salt comprises 90%-100% by mass of KNO3 and 0%-10% by mass of NaNO3; in the first molten salt, the mass fraction of KNO3 can be 90%, 92%, 94%, 96%, 98% or 100%; the mass fraction of NaNO3 can be 0%, 1%, 2%, 4%, 6%, 8% or 10%.

[0046] In some embodiments, before immersing the glass in the first molten salt for the first ion exchange treatment, a preheating step is included. The preheating conditions include: a temperature of 350-380°C, which can be 350°C, 360°C, 370°C, or 380°C; and a time of 10-40 min, which can be 10 min, 12 min, 14 min, 16 min, 18 min, 20 min, 25 min, 30 min, 35 min, or 40 min.

[0047] In some embodiments, the glass is aluminosilicate glass.

[0048] In some embodiments, the aluminosilicate glass is lithium aluminosilicate glass or sodium aluminosilicate glass.

[0049] In some embodiments, the lithium aluminum silicon glass comprises glass of model GG5 or GG8 manufactured by Corning Incorporated.

[0050] In some embodiments, the sodium aluminum silicate glass comprises GG3 glass manufactured by Corning Incorporated.

[0051] In some embodiments, the aluminosilicate glass is sodium aluminum silicate glass;

[0052] The first molten salt comprises the following components by mass fraction: 1%-25% NaNO3 and 75%-99% KNO3, which can be 1% NaNO3 and 99% KNO3, 3% NaNO3 and 97% KNO3, 10% NaNO3 and 90% KNO3, 15% NaNO3 and 85% KNO3, or 25% NaNO3 and 75% KNO3;

[0053] The conditions for the first ion exchange treatment include: a temperature of 420-440℃, which can be 420℃, 425℃, 430℃, 435℃ or 440℃; and a time of 300-420min, which can be 300min, 320min, 340min, 360min, 380min, 400min or 420min.

[0054] The second molten salt is KNO3;

[0055] The conditions for the second ion exchange treatment include: a temperature of 400-440℃, which can be 400℃, 410℃, 420℃, 430℃ or 440℃; and a time of 10-60min, which can be 10min, 20min, 30min, 40min, 50min or 60min.

[0056] In some embodiments, the aluminosilicate glass is lithium aluminosilicate glass;

[0057] The first molten salt comprises the following components by mass fraction: 2%-15% LiNO3 and 58%-98% KNO3, which can be 2% LiNO3 and 98% KNO3, 4% LiNO3 and 96% KNO3, 5% LiNO3 and 95% KNO3, 8% LiNO3 and 92% KNO3, 10% LiNO3 and 90% KNO3, or 15% LiNO3 and 85% KNO3;

[0058] The conditions for the first ion exchange treatment include: a temperature of 380-440℃, which can be 380℃, 390℃, 400℃, 405℃, 410℃, 420℃, 430℃, or 440℃; and a time of 10-75 min, which can be 10 min, 12 min, 15 min, 18 min, 20 min, 30 min, 40 min, 50 min, 60 min, 65 min, 70 min, or 75 min.

[0059] The second molten salt comprises the following components by mass fraction: 0%-10% NaNO3 and 90%-100% KNO3;

[0060] The conditions for the second ion exchange treatment include: a temperature of 380-440℃, which can be 380℃, 390℃, 400℃, 410℃, 420℃, 430℃ or 440℃; and a time of 30-60min, which can be 30min, 35min, 40min, 45min, 50min, 55min or 60min.

[0061] In a second aspect, this application provides a chemically strengthened glass prepared by the chemical strengthening method for glass described in the first aspect.

[0062] In some embodiments, the coefficient of thermal expansion of the chemically strengthened glass is 0.010%-0.052%, and can be 0.010%, 0.012%, 0.013%, 0.014%, 0.015%, 0.016%, 0.020%, 0.021%, 0.025%, 0.026%, 0.030%, 0.031%, 0.034%, 0.038%, 0.040%, 0.042%, 0.045%, 0.050%, 0.051%, or 0.052%.

[0063] In this application, the expansion coefficient is the linear expansion coefficient.

[0064] The third aspect of this application provides the application of chemically strengthened glass prepared by the chemical strengthening method of the glass described in the first aspect or the chemically strengthened glass described in the second aspect as a glass cover for electronic devices.

[0065] The embodiments of this application will be described in detail below with reference to examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this application. For experimental methods in the following embodiments where specific conditions are not specified, please refer to the guidelines given in this application, or follow experimental manuals or conventional conditions in the art, or follow the conditions recommended by the manufacturer, or refer to experimental methods known in the art.

[0066] As an example, the sources of raw materials in this application embodiment are as follows:

[0067] GG3, GG5, and GG8 glass: These glass models are GG3, GG5, and GG8, respectively. They were all purchased from Corning Incorporated in the United States, and their dimensions are all 165.74mm × 74.35mm × 0.55mm (length × width × thickness).

[0068] Example 1

[0069] The chemical strengthening methods for glass are as follows:

[0070] GG3 glass was preheated at 380℃ for 15 min, and then immersed in a first molten salt (composed of 1% NaNO3 and 99% KNO3) for a first ion exchange treatment at 440℃ for 300 min. Then it was immersed in a second molten salt (KNO3) for a second ion exchange treatment at 420℃ for 20 min to prepare chemically strengthened glass.

[0071] Example 2

[0072] The chemical strengthening methods for glass are as follows:

[0073] GG3 glass was preheated at 380℃ for 15 min, and then immersed in a first molten salt (composed of 3% NaNO3 and 97% KNO3) for a first ion exchange treatment at 440℃ for 300 min. Then it was immersed in a second molten salt (KNO3) for a second ion exchange treatment at 420℃ for 20 min to prepare chemically strengthened glass.

[0074] Example 3

[0075] The chemical strengthening methods for glass are as follows:

[0076] GG3 glass was preheated at 380℃ for 15 min, and then immersed in a first molten salt (composed of 10% NaNO3 and 90% KNO3) for a first ion exchange treatment at 440℃ for 300 min. Then it was immersed in a second molten salt (KNO3) for a second ion exchange treatment at 420℃ for 20 min to prepare chemically strengthened glass.

[0077] Example 4

[0078] The chemical strengthening methods for glass are as follows:

[0079] GG3 glass was preheated at 380℃ for 15 min, and then immersed in a first molten salt (composed of 15% NaNO3 and 85% KNO3 by mass) for a first ion exchange treatment at 440℃ for 300 min. Then it was immersed in a second molten salt (KNO3) for a second ion exchange treatment at 420℃ for 20 min to prepare chemically strengthened glass.

[0080] Example 5

[0081] The chemical strengthening methods for glass are as follows:

[0082] GG3 glass was preheated at 380℃ for 15 min, and then immersed in a first molten salt (composed of 25% NaNO3 and 75% KNO3 by mass) for a first ion exchange treatment at 440℃ for 300 min. Then it was immersed in a second molten salt (KNO3) for a second ion exchange treatment at 420℃ for 20 min to prepare chemically strengthened glass.

[0083] Example 6

[0084] The chemical strengthening methods for glass are as follows:

[0085] GG3 glass was preheated at 380℃ for 15 min, and then immersed in a first molten salt (composed of 10% NaNO3 and 90% KNO3) for a first ion exchange treatment at 420℃ for 420 min. Then it was immersed in a second molten salt (KNO3) for a second ion exchange treatment at 420℃ for 20 min to prepare chemically strengthened glass.

[0086] Example 7

[0087] The chemical strengthening methods for glass are as follows:

[0088] GG3 glass was preheated at 380℃ for 15 min, and then immersed in a first molten salt (composed of 10% NaNO3 and 90% KNO3) for a first ion exchange treatment at 440℃ for 300 min. Then it was immersed in a second molten salt (KNO3) for a second ion exchange treatment at 420℃ for 10 min to prepare chemically strengthened glass.

[0089] Example 8

[0090] The chemical strengthening methods for glass are as follows:

[0091] GG3 glass was preheated at 380℃ for 15 min, and then immersed in a first molten salt (composed of 10% NaNO3 and 90% KNO3) for a first ion exchange treatment at 440℃ for 300 min. Then it was immersed in a second molten salt (KNO3) for a second ion exchange treatment at 420℃ for 40 min to prepare chemically strengthened glass.

[0092] Example 9

[0093] The chemical strengthening methods for glass are as follows:

[0094] GG3 glass was preheated at 380℃ for 15 min, and then immersed in a first molten salt (composed of 10% NaNO3 and 90% KNO3) for a first ion exchange treatment at 440℃ for 300 min. Then it was immersed in a second molten salt (KNO3) for a second ion exchange treatment at 420℃ for 60 min to prepare chemically strengthened glass.

[0095] Example 10

[0096] The chemical strengthening methods for glass are as follows:

[0097] GG3 glass was preheated at 350℃ for 15 min, and then immersed in a first molten salt (composed of 10% NaNO3 and 90% KNO3 by mass) for a first ion exchange treatment at 440℃ for 300 min. Then it was immersed in a second molten salt (KNO3) for a second ion exchange treatment at 420℃ for 20 min to prepare chemically strengthened glass.

[0098] Example 11

[0099] The chemical strengthening methods for glass are as follows:

[0100] GG5 glass was preheated at 380℃ for 15 min, and then immersed in a first molten salt (composed of 2% LiNO3 and 98% KNO3) for a first ion exchange treatment at 405℃ for 10 min. Then, it was immersed in a second molten salt (composed of 10% NaNO3 and 90% KNO3) for a second ion exchange treatment at 380℃ for 30 min to prepare chemically strengthened glass.

[0101] Example 12

[0102] The chemical strengthening methods for glass are as follows:

[0103] GG5 glass was preheated at 380℃ for 15 min, and then immersed in a first molten salt (composed of 2% LiNO3 and 98% KNO3) for a first ion exchange treatment at 405℃ for 10 min. Then it was immersed in a second molten salt (composed of 10% NaNO3 and 90% KNO3) for a second ion exchange treatment at 380℃ for 40 min to prepare chemically strengthened glass.

[0104] Example 13

[0105] The chemical strengthening methods for glass are as follows:

[0106] GG5 glass was preheated at 380℃ for 15 min, and then immersed in a first molten salt (composed of 4% LiNO3 and 96% KNO3) for a first ion exchange treatment at 405℃ for 20 min. Then it was immersed in a second molten salt (composed of 10% NaNO3 and 90% KNO3) for a second ion exchange treatment at 380℃ for 40 min to prepare chemically strengthened glass.

[0107] Example 14

[0108] The chemical strengthening methods for glass are as follows:

[0109] GG5 glass was preheated at 380℃ for 15 min, and then immersed in a first molten salt (composed of 10% LiNO3 and 90% KNO3) for a first ion exchange treatment at 405℃ for 20 min. Then, it was immersed in a second molten salt (composed of 10% NaNO3 and 90% KNO3) for a second ion exchange treatment at 380℃ for 60 min to prepare chemically strengthened glass.

[0110] Example 15

[0111] The chemical strengthening methods for glass are as follows:

[0112] GG8 glass was preheated at 380℃ for 15 min, and then immersed in a first molten salt (composed of 5% LiNO3 and 95% KNO3) for a first ion exchange treatment at 405℃ for 60 min. Then it was immersed in a second molten salt (composed of 10% NaNO3 and 90% KNO3) for a second ion exchange treatment at 380℃ for 35 min to prepare chemically strengthened glass.

[0113] Example 16

[0114] The chemical strengthening methods for glass are as follows:

[0115] GG8 glass was preheated at 380℃ for 15 min, and then immersed in a first molten salt (composed of 5% LiNO3 and 95% KNO3) for a first ion exchange treatment at 405℃ for 60 min. Then it was immersed in a second molten salt (composed of 10% NaNO3 and 90% KNO3) for a second ion exchange treatment at 380℃ for 45 min to prepare chemically strengthened glass.

[0116] Example 17

[0117] The chemical strengthening methods for glass are as follows:

[0118] GG8 glass was preheated at 380℃ for 15 min, and then immersed in a first molten salt (composed of 10% LiNO3 and 90% KNO3) for a first ion exchange treatment at 405℃ for 75 min. Then it was immersed in a second molten salt (composed of 10% NaNO3 and 90% KNO3) for a second ion exchange treatment at 380℃ for 45 min to prepare chemically strengthened glass.

[0119] Example 18

[0120] The chemical strengthening methods for glass are as follows:

[0121] GG8 glass was preheated at 380℃ for 15 min, and then immersed in a first molten salt (composed of 15% LiNO3 and 85% KNO3) for a first ion exchange treatment at 405℃ for 75 min. Then it was immersed in a second molten salt (composed of 10% NaNO3 and 90% KNO3) for a second ion exchange treatment at 380℃ for 60 min to prepare chemically strengthened glass.

[0122] Comparative Example 1

[0123] The chemical strengthening methods for glass are as follows:

[0124] GG3 glass was preheated at 380℃ for 15 minutes and then immersed in tempering molten salt (KNO3) for chemical strengthening treatment at 420℃ for 300 minutes to prepare chemically strengthened glass.

[0125] Comparative Example 2

[0126] The chemical strengthening methods for glass are as follows:

[0127] GG5 glass was preheated at 380℃ for 15 min, and then immersed in a first molten salt (composed of 38% NaNO3 and 62% KNO3) for a first ion exchange treatment at 380℃ for 125 min. Then it was immersed in a second molten salt (composed of 9% NaNO3 and 91% KNO3) for a second ion exchange treatment at 380℃ for 20 min to prepare chemically strengthened glass.

[0128] Comparative Example 3

[0129] The chemical strengthening methods for glass are as follows:

[0130] GG8 glass was preheated at 380℃ for 15 min, and then immersed in a first molten salt (composed of 50% NaNO3 and 50% KNO3 by mass) for a first ion exchange treatment at 440℃ for 90 min. Then it was immersed in a second molten salt (composed of 2% NaNO3 and 98% KNO3 by mass) for a second ion exchange treatment at 390℃ for 20 min to prepare chemically strengthened glass.

[0131] Comparative Example 4

[0132] The chemical strengthening method of the glass in Comparative Example 4 is basically the same as that in Example 1, except that the first molten salt is KNO3; and the chemically strengthened glass is prepared according to the method in the example.

[0133] Specifically, the chemical strengthening methods for glass are as follows:

[0134] GG3 glass was preheated at 380℃ for 15 min, and then immersed in the first molten salt (KNO3) for the first ion exchange treatment at 440℃ for 300 min. Then it was immersed in the second molten salt (KNO3) for the second ion exchange treatment at 420℃ for 20 min to prepare chemically strengthened glass.

[0135] Comparative Example 5

[0136] The chemical strengthening method of the glass in Comparative Example 5 is basically the same as that in Example 1, except that the first molten salt is composed of 50% by mass of NaNO3 and 50% by mass of KNO3; and the chemically strengthened glass is prepared according to the method of the Example.

[0137] Specifically, the chemical strengthening methods for glass are as follows:

[0138] GG3 glass was preheated at 380℃ for 15 min, and then immersed in a first molten salt (composed of 50% NaNO3 and 50% KNO3 by mass) for a first ion exchange treatment at 440℃ for 300 min. Then it was immersed in a second molten salt (KNO3) for a second ion exchange treatment at 420℃ for 20 min to prepare chemically strengthened glass.

[0139] Comparative Example 6

[0140] The chemical strengthening method of the glass in Comparative Example 6 is basically the same as that in Example 3, except that the second ion exchange treatment time is 3 minutes; and the chemically strengthened glass is prepared according to the method in Example 3.

[0141] Specifically, the chemical strengthening methods for glass are as follows:

[0142] GG3 glass was preheated at 380℃ for 15 min, and then immersed in a first molten salt (composed of 10% NaNO3 and 90% KNO3 by mass) for a first ion exchange treatment at 440℃ for 300 min. Then it was immersed in a second molten salt (KNO3) for a second ion exchange treatment at 420℃ for 3 min to prepare chemically strengthened glass.

[0143] Comparative Example 7

[0144] The chemical strengthening method of the glass in Comparative Example 7 is basically the same as that in Example 3, except that the second ion exchange treatment time is 80 min; and the chemically strengthened glass is prepared according to the method in Example 3.

[0145] Specifically, the chemical strengthening methods for glass are as follows:

[0146] GG3 glass was preheated at 380℃ for 15 min, and then immersed in a first molten salt (composed of 10% NaNO3 and 90% KNO3) for a first ion exchange treatment at 440℃ for 300 min. Then it was immersed in a second molten salt (KNO3) for a second ion exchange treatment at 420℃ for 80 min to prepare chemically strengthened glass.

[0147] Comparative Example 8

[0148] The chemical strengthening methods for glass are as follows:

[0149] GG3 glass was immersed in a first molten salt (composed of 50% NaNO3 and 50% KNO3 by mass) for a first ion exchange treatment at a temperature of 375°C for 660 min; then it was immersed in a second molten salt (KNO3) for a second ion exchange treatment at a temperature of 405°C for 150 min to prepare chemically strengthened glass.

[0150] The process parameters for the chemical strengthening methods of the glasses in Examples 1-18 and Comparative Examples 1-8 are shown in Table 1.

[0151] Table 1. Process parameters for chemical strengthening methods of glass

[0152]

[0153]

[0154]

[0155] " / " indicates that the action was not performed.

[0156] Experimental Example 1

[0157] For Examples 1-18 and Comparative Examples 1-8, the dimensional changes of each glass before and after strengthening were measured using an SWD fully automatic image measuring instrument, and the coefficient of thermal expansion was calculated. An FMS-6000 stress tester was used to measure the CS (compressive stress value of potassium-sodium exchange), CSK (compressive stress value of sodium-lithium exchange), DOL (depth of stress layer of potassium-sodium exchange), and DOC (depth of stress layer of sodium-lithium exchange) of each glass after strengthening. Ten pieces of chemically strengthened glass from each example were used as samples, and the average CS, average CSK, average DOL, and average DOC values ​​of the ten samples were taken as CS, CSK, DOL, and DOC. The results are shown in Table 2.

[0158] Table 2 Properties of Chemically Strengthened Glass

[0159]

[0160] " / " indicates that it was not measured.

[0161] The results in Table 2 show that, compared with Comparative Examples 1-8, the chemical strengthening method of glass used in Examples 1-18 of this application can prepare chemically strengthened glass with low expansion coefficient and high compressive stress in a shorter time.

[0162] Compared to Comparative Example 4, which used only KNO3 as the first molten salt, Example 1 used 1% NaNO3 and 99% KNO3 by mass as the first molten salt. The coefficient of thermal expansion of the prepared chemically strengthened glass decreased from 0.082% to 0.025%, a reduction of 70%, while CS and DOL showed no significant change. This indicates that Example 1 of this application, using a composite of NaNO3 and KNO3 as the first molten salt, significantly reduced the expansion dimension of the prepared chemically strengthened glass, balancing high compressive stress and stress layer depth, resulting in good glass strengthening performance.

[0163] Comparing Examples 1-5 and Comparative Example 5, it can be seen that under the conditions of using 1%-50% by mass of NaNO3 and 50%-99% by mass of KNO3 in the first molten salt, as the KNO3 content in the first molten salt increases, the coefficient of thermal expansion of the chemically strengthened glass shows a trend of first decreasing and then increasing, the DOL shows a decreasing trend, and the CS shows no significant change. This indicates that the chemically strengthened glass prepared in this application using 75%-99% by mass of KNO3 in the first molten salt can achieve both low coefficient of thermal expansion and high-pressure stress performance.

[0164] Compared with Comparative Examples 6-7, Examples 3 and 7-10 of this application, by controlling the time of the second ion exchange treatment within 10-60 minutes, can prepare chemically strengthened glasses that can balance low expansion coefficient and high pressure stress performance.

[0165] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0166] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for chemically strengthening glass, characterized in that, Includes the following steps: Chemically strengthened glass is prepared by immersing the glass in a first molten salt for a first ion exchange treatment, and then immersing it in a second molten salt for a second ion exchange treatment. The first molten salt comprises 75%-99% by mass of KNO3 and 1%-25% by mass of a first alkali metal salt; the first alkali metal in the first alkali metal salt is an alkali metal ion in the glass. The conditions for the first ion exchange treatment included: a temperature of 405-440℃ and a time of 10-420 min. The second molten salt comprises 90%-100% by mass of KNO3; The conditions for the second ion exchange treatment include: a temperature of 380-420℃ and a time of 10-60 min.

2. The chemical strengthening method for glass according to claim 1, characterized in that, The first alkali metal salt includes NaNO3 and / or LiNO3.

3. The chemical strengthening method for glass according to claim 1 or 2, characterized in that, The second molten salt also includes NaNO3.

4. The chemical strengthening method for glass according to claim 1 or 2, characterized in that, Before immersing the glass in the first molten salt for the first ion exchange treatment, the process also includes a preheating step for the glass, with preheating conditions including a temperature of 350-380℃ and a time of 10-40 minutes.

5. The chemical strengthening method for glass according to claim 1 or 2, characterized in that, The glass is aluminosilicate glass.

6. The chemical strengthening method for glass according to claim 5, characterized in that, The aluminosilicate glass is lithium aluminosilicate glass or sodium aluminosilicate glass.

7. The chemical strengthening method for glass according to claim 6, characterized in that, It meets at least one of the following characteristics: (1) The aluminosilicate glass is sodium aluminum silicate glass; The first molten salt comprises the following components by mass fraction: 1%-25% NaNO3 and 75%-99% KNO3; The conditions for the first ion exchange treatment included: a temperature of 420-440℃ and a time of 300-420 min. The second molten salt is KNO3; The conditions for the second ion exchange treatment include: a temperature of 400-440℃ and a time of 10-60 min; (2) The aluminosilicate glass is lithium aluminosilicate glass; The first molten salt comprises the following components by mass fraction: 2%-15% LiNO3 and 85%-98% KNO3; The conditions for the first ion exchange treatment include: temperature of 380-440℃; time of 10-75 min. The second molten salt comprises the following components by mass fraction: 0%-10% NaNO3 and 90%-100% KNO3; The conditions for the second ion exchange treatment include: a temperature of 380-440℃ and a time of 30-60 min.

8. A chemically strengthened glass, characterized in that, Prepared by the chemical strengthening method of the glass according to any one of claims 1-7.

9. The chemically strengthened glass according to claim 8, characterized in that, The coefficient of thermal expansion of the chemically strengthened glass is 0.010%-0.052%.

10. The application of chemically strengthened glass prepared by the chemical strengthening method of any one of claims 1-7 or the chemically strengthened glass of claim 8 as a glass cover for electronic devices.

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