Glass cover plate with hardness and toughness and preparation method thereof

Abstract

The application discloses a glass cover plate with hardness and toughness and a preparation method thereof, wherein the glass substrate of the glass cover plate is a gradient layered component structure, sequentially comprising a surface layer, a transition layer and a core layer, each layer has a specific same component, and the component content of the same component has a gradual change characteristic, and each layer also has a relatively different component, so that the hardness and toughness of the glass cover plate can be considered. In the preparation process, the stress layer depth reaches 100-120 μm through a secondary ion exchange process, and the edge stress is increased by more than 50%, which can solve the problems of traditional glass edge embrittlement and easy chipping, can simultaneously adapt to the design requirements of curved screens and special-shaped screens, and is feasible for mass production, controllable in cost, and the overall cost is reduced by 40-50% compared with microcrystalline glass, the yield of mass production can reach more than 85%, and various functions such as high hardness, high toughness, oil-repellent, antistatic, stress relaxation resistance and the like can be realized simultaneously.

Description

Technical Field

[0001] This invention relates to the field of glass cover plate equipment technology, and in particular to a glass cover plate that balances hardness and toughness, and its preparation method. Background Technology

[0002] Glass covers are mainly divided into chemically strengthened glass (aluminosilicate / lithium aluminosilicate), microcrystalline glass, etc. They are the core carriers of mobile phone display and touch functions. Their hardness (such as scratch resistance) and toughness (such as impact resistance) directly determine the user experience and the product's lifespan.

[0003] In existing technologies, there is an irreconcilable contradiction between the hardness and toughness of glass covers: traditional chemically strengthened glass forms surface compressive stress through ion exchange, and its Mohs hardness can only reach 6-7. It is easily scratched by quartz sand (Mohs hardness 7) in the daily environment, and the stress layer depth is limited (usually <50μm), making the edges prone to chipping. In a 1.5-meter drop test, about 30% of the samples will show cracks. Although microcrystalline glass can increase the hardness to 9H, close to the hardness of diamond, and significantly improve scratch resistance, its toughness is greatly reduced. Its density is higher than that of ordinary glass, making it more prone to breakage under sharp impacts. Moreover, the problem of edge embrittlement is prominent, and the corner breakage rate is still as high as 40% when dropped.

[0004] Currently, most glass covers are optimized for a single performance indicator, failing to address the balance between hardness and toughness from aspects such as composition, process, and structure. This results in high-performance glass covers either being prohibitively expensive and difficult to mass-produce, or failing to meet users' dual needs for scratch resistance and drop resistance during long-term use.

[0005] Therefore, developing a glass cover that combines high hardness and high toughness, with a mature manufacturing process and controllable cost, has become a pressing technical challenge for the industry. Summary of the Invention

[0006] This application provides a glass cover plate that balances hardness and toughness, and its preparation method. It can balance the hardness and toughness of the glass cover plate, achieve a Mohs hardness of ≥8.5, improve impact resistance by more than 60%, control production costs, adapt to mass production needs, and solve derivative problems such as edge embrittlement and stress relaxation.

[0007] The first aspect of this application provides a glass cover that balances hardness and toughness. The glass substrate of the glass cover has a gradient layered component structure, comprising a surface layer, a transition layer, and a core layer. The surface layer is the layer exposed during use. The components of the surface layer, by weight percentage, are: SiO2 68-72%, Al2O3 12-15%, Li2O 6-8%, ZrO2 3-5%, MgO 1-2%, and TiO2 0.5-1%. The components of the transition layer, by weight percentage, are: SiO2 70-73%, Al2O3 10-12%, Li2O 4-6%, ZrO2 1-3%, MgO 2-3%; The core layer comprises the following components by weight percentage: SiO2 72-75%, Al2O3 8-10%, Li2O 2-4%, MgO 3-5%, and CaO 1-2%. Specifically, for the components SiO2, Al2O3, Li2O, and MgO, the content of the transition layer is between that of the surface layer and the core layer, exhibiting a gradual change in component content.

[0008] In one possible implementation, the thickness of the surface layer is 50-80 μm, the thickness of the transition layer is 30-50 μm, the thickness of the core layer is 400-500 μm, and the overall thickness of the glass cover is 500-600 μm.

[0009] In one possible implementation, the surface layer comprises the following components by weight percentage: SiO2 70%, Al2O3 13%, Li2O 7%, ZrO2 4%, MgO 1.5%, TiO2 0.5%; The components of the transition layer by weight percentage are: SiO2 71%, Al2O3 11%, Li2O 5%, ZrO2 2%, MgO 2.5%; The core layer is composed of the following components by weight percentage: SiO2 73%, Al2O 39%, Li2O 3%, MgO 4%, and CaO 1.5%.

[0010] In one possible implementation, the surface layer comprises the following components by weight percentage: SiO2 68%, Al2O3 15%, Li2O 8%, ZrO2 5%, MgO 1%, TiO2 1%; The components of the transition layer by weight percentage are: SiO2 70%, Al2O3 12%, Li2O 6%, ZrO2 3%, MgO 2%; The core layer is composed of the following components by weight percentage: SiO2 72%, Al2O3 10%, Li2O 4%, MgO 3%, and CaO 2%.

[0011] In one possible implementation, the surface layer comprises the following components by weight percentage: SiO2 72%, Al2O3 12%, Li2O 6%, ZrO2 3%, MgO 2%, TiO2 0.5%; The components of the transition layer by weight percentage are: SiO2 73%, Al2O3 10%, Li2O 4%, ZrO2 1%, MgO 3%; The core layer is composed of the following components by weight percentage: SiO2 75%, Al2O3 8%, Li2O 2%, MgO 5%, and CaO 1%.

[0012] In one possible implementation, the surface of the surface layer is further coated with a biomimetic composite coating, the components of which, by weight percentage, are: 30-40% nano-SiO2, 20-30% fluorine-modified polyurethane, 15-20% polysiloxane, 5-10% coupling agent, and 10-15% ethanol solvent, wherein the particle size of the nano-SiO2 is 20-50 nm.

[0013] The second aspect of this application provides a method for preparing a glass cover plate that balances hardness and toughness as described above, comprising the following steps: S10, prepare gradient component glass cover substrate by placing the surface layer, transition layer and core layer components into a melting furnace and melting them uniformly at 1600-1650℃. Then, through a layered casting process, the surface layer, transition layer and core layer melts are sequentially bonded and gradually mixed. After cooling and forming, the gradient component glass substrate is obtained by grinding and polishing. S20, one-time ion exchange, the obtained gradient component glass substrate is placed in the first molten salt bath, the temperature is 380-400℃, and the temperature is maintained for 2-3 hours; S30, intermediate cooling, slowly cooled to room temperature in an inert gas environment; S40, secondary ion exchange, involves placing a gradient-component glass substrate into a second molten salt bath at a temperature of 420-440℃ for 1-1.5 hours. S50, clean and dry, wash several times in deionized water, dry for 1-2 hours to obtain a reinforced glass substrate.

[0014] In one possible implementation, in step S20, the first molten salt bath is a mixed solution of 90-95% KNO3 and 5-10% NaNO3; in step S40, the second molten salt bath is a mixed solution of 85-90% KNO3 and 10-15% LiNO3.

[0015] In one possible implementation, in step S30, the inert gas is nitrogen, and the cooling rate is 5-10 °C / min; in step S50, the temperature of the drying oven used for drying is 100-120 °C.

[0016] In one possible implementation, the preparation method further includes step S60, which involves applying the biomimetic composite coating using a vacuum spraying process, with a spraying pressure of 0.3-0.5 MPa and a spraying distance of 15-20 cm; after spraying, the coating is placed in a curing oven at 150-180°C for 2-3 hours for curing.

[0017] Beneficial effects: Compared with the prior art, the glass cover plate and its preparation method provided in this application, which balance hardness and toughness, can: 1. Balancing the hardness and toughness of glass covers: The surface layer of the glass has a Mohs hardness of 8.5-9H, which can effectively resist scratches from everyday hard objects such as quartz sand. Its scratch resistance is better than that of traditional chemically strengthened glass (6-7 levels) and close to that of microcrystalline glass (9H). The core layer toughness is improved by more than 60%, and the breakage rate is reduced to less than 5% in a 1.5-meter drop test. It does not shatter under sharp impact, thus solving the core defect of the mutual restriction between hardness and toughness in existing glass. 2. Edge performance optimization: Through a secondary ion exchange process, the stress layer depth reaches 100-120μm, and the edge stress is increased by more than 50%, which can solve the problems of edge brittleness and easy chipping of traditional glass, and can adapt to the design requirements of curved screens and irregular screens. 3. Enhanced Environmental Adaptability: The biomimetic composite coating not only improves scratch resistance but also possesses excellent oleophobicity (contact angle ≥110°), extending the oleophobic layer lifespan to 18-24 months and preventing fingerprint and oil stains from adhering to it. It also has good antistatic properties, reducing dust adsorption without affecting touch sensitivity. After being placed in a high temperature and high humidity environment (temperature 60℃, humidity 85%) for 1000 hours, the stress relaxation rate is ≤5%, and the long-term performance is stable. 4. Feasible for mass production and controllable cost: The gradient component preparation adopts an improved version of the existing layered melting equipment, and the secondary ion exchange process does not require the addition of special equipment. The biomimetic coating process is mature. The overall cost is reduced by 40-50% compared to microcrystalline glass, and the mass production yield can reach more than 85%, which is suitable for large-scale production and can be widely used in mid-to-high-end flagship mobile phones. 5. Multifunctional integration: It simultaneously achieves multiple functions such as high hardness, high toughness, oleophobicity, antistatic properties, and stress relaxation resistance, without the need for additional multi-layer structures, thus avoiding the problems of glass interface peeling and decreased touch sensitivity in composite structures.

[0018] These and other objects, features and advantages of the present invention will become fully apparent from the following detailed description. Attached Figure Description

[0019] Figure 1 A schematic flowchart of the method for preparing a glass cover plate that balances hardness and toughness according to this application is shown. Detailed Implementation

[0020] The following description is intended to disclose the present invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0021] Those skilled in the art should understand that, in the disclosure of this specification, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting the present invention.

[0022] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will also be understood that terms, such as those defined in commonly used dictionaries, shall be interpreted as having a meaning consistent with their meaning in the context of the relevant art and shall not be interpreted as having an idealized or overly formal meaning unless expressly so defined herein.

[0023] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0024] To address the shortcomings of existing glass cover plates where hardness and toughness are mutually restrictive and scratch and impact resistance cannot be simultaneously achieved, this application provides a glass cover plate that balances hardness and toughness, as well as its preparation method. This method can achieve a Mohs hardness of ≥8.5 and an impact resistance improvement of over 60%, while also controlling production costs, adapting to mass production needs, and solving derivative problems such as edge embrittlement and stress relaxation.

[0025] Specifically, the first aspect of this application provides a glass cover that balances hardness and toughness. The glass substrate of the glass cover has a gradient layered component structure, which includes a surface layer, a transition layer, and a core layer. The surface layer is the layer exposed during use. The components of the surface layer by weight percentage are: SiO2 68-72%, Al2O3 12-15%, Li2O 6-8%, ZrO2 3-5%, MgO 1-2%, and TiO2 0.5-1%. ZrO2 and TiO2 work synergistically to improve the hardness and wear resistance of the surface layer, and Li2O provides a sufficient ion source for subsequent ion exchange. The transition layer comprises the following components by weight percentage: SiO2 70-73%, Al2O3 10-12%, Li2O 4-6%, ZrO2 1-3%, and MgO 2-3%. The content of SiO2, Al2O3, Li2O, and MgO in the transition layer falls between that of the surface layer and the core layer, exhibiting a gradual change in component content. A gradual mixing process is used to eliminate abrupt changes in composition between the surface and core layers, enhance interlayer bonding, and prevent delamination during temperature changes. This gradual change should be understood as the component content gradually increasing or decreasing from the surface to the core layer, rather than the same component having the same content in adjacent layers or exhibiting a zigzag change across the three layers. For example, the content of SiO2 gradually increases from the surface to the core layer; similarly, the content of Al2O3 gradually decreases from the surface to the core layer. The core layer is composed of the following components by weight percentage: SiO2 72-75%, Al2O3 8-10%, Li2O 2-4%, MgO 3-5%, and CaO 1-2%. By reducing the content of hard and brittle components (ZrO2, TiO2) and increasing the proportion of tough components (MgO, CaO), the impact resistance and toughness of the glass core layer are improved, thus preventing it from shattering under sharp impact.

[0026] In some embodiments, the thickness of the surface layer is 50-80 μm, the thickness of the transition layer is 30-50 μm, the thickness of the core layer is 400-500 μm, and the overall thickness of the glass cover is 500-600 μm.

[0027] The gradient components are prepared using a layered melting-gradient bonding process to ensure uniform distribution of each layer of components, with no obvious interfaces between layers, and the overall thickness is controlled at 500-600μm, which is suitable for the thickness requirements of current glass cover plates.

[0028] In some embodiments, the surface of the outer layer is further coated with a biomimetic composite coating to achieve a balance of scratch resistance, oleophobicity, and antistatic properties, while also enhancing toughness. The biomimetic composite coating comprises, by weight percentage: 30-40% nano-SiO2, 20-30% fluorinated modified polyurethane, 15-20% polysiloxane, 5-10% coupling agent (e.g., KH-550), and 10-15% ethanol solvent. The nano-SiO2 has a particle size of 20-50 nm to improve the hardness of the composite coating. The fluorinated modified polyurethane enhances the flexibility and oleophobicity of the composite coating, while the polysiloxane improves its antistatic properties. Simultaneously, the coupling agent strengthens the adhesion between the composite coating and the glass substrate (i.e., the outer layer).

[0029] refer to Figure 1The second aspect of this application provides a method for preparing a glass cover plate that balances hardness and toughness as described above, comprising the following steps: S10, prepare gradient component glass cover substrate by placing the surface layer, transition layer and core layer components into a melting furnace and melting them uniformly at 1600-1650℃. Then, through a layered casting process, the surface layer, transition layer and core layer melts are sequentially bonded and gradually mixed. After cooling and forming, the gradient component glass substrate is obtained by grinding and polishing. S20, a single ion exchange process, involves placing the resulting gradient-component glass substrate into a first molten salt bath at 380-400℃ for 2-3 hours. The first molten salt bath is preferably a mixed solution of 90-95% KNO3 and 5-10% NaNO3, resulting in a 100% molten salt solution. This allows for the utilization of the high Li content on the surface. + (Lithium ions) and K in molten salt + (Potassium ions), Na + (Sodium ions) undergo initial exchange, forming initial surface compressive stress, with the stress layer depth reaching 60-80μm; S30, intermediate cooling, is slowly cooled to room temperature in an inert gas environment, wherein the inert gas can be nitrogen. During the cooling process, the cooling rate is preferably 5-10℃ / min, so as to avoid the generation of internal stress by rapid cooling. S40, secondary ion exchange: The gradient-component glass substrate is placed in a second molten salt bath at 420-440℃ for 1-1.5 hours. The second molten salt bath is preferably a mixed solution of 85-90% KNO3 and 10-15% LiNO3, resulting in a 100% molten salt solution. This solution can target the Li2O3 transition layer and the surface layer. + (Lithium ions) undergo secondary exchange to further enhance the surface compressive stress, while making the stress decrease smoothly from the surface to the core layer. The stress layer depth reaches 100-120μm, and the edge stress is increased by more than 50%, solving the defect of edge embrittlement in traditional ion exchange. S50, clean and dry, wash several times in deionized water, such as 3-5 times, and dry for 1-2 hours. The temperature of the drying oven used for drying is 100-120℃, and finally a reinforced glass substrate is obtained.

[0030] In some embodiments, the preparation method further includes step S60, which involves coating the surface of the finally obtained reinforced glass substrate (i.e., the surface of the outer layer) with a biomimetic composite coating. Step S60 employs a vacuum spraying process to coat the biomimetic composite coating, wherein the spraying pressure is 0.3-0.5 MPa, the spraying distance is 15-20 cm, and the thickness of the composite coating is preferably 5-10 μm. After spraying, the entire substrate is placed in a curing oven at 150-180°C for 2-3 hours to ensure that the coating is tightly bonded to the glass substrate without peeling or bubbles. Finally, the substrate is cooled to room temperature to obtain the final glass cover product.

[0031] Therefore, the glass cover plate and its preparation method that combine hardness and toughness provided in this application can: 1. Balancing the hardness and toughness of glass covers: The surface layer of the glass has a Mohs hardness of 8.5-9H, which can effectively resist scratches from everyday hard objects such as quartz sand. Its scratch resistance is better than that of traditional chemically strengthened glass (6-7 levels) and close to that of microcrystalline glass (9H). The core layer toughness is improved by more than 60%, and the breakage rate is reduced to less than 5% in a 1.5-meter drop test. It does not shatter under sharp impact, thus solving the core defect of the mutual restriction between hardness and toughness in existing glass. 2. Edge performance optimization: Through a secondary ion exchange process, the stress layer depth reaches 100-120μm, and the edge stress is increased by more than 50%, which can solve the problems of edge brittleness and easy chipping of traditional glass, and can adapt to the design requirements of curved screens and irregular screens. 3. Enhanced Environmental Adaptability: The biomimetic composite coating not only improves scratch resistance but also possesses excellent oleophobicity (contact angle ≥110°), extending the oleophobic layer lifespan to 18-24 months and preventing fingerprint and oil stains from adhering to it. It also has good antistatic properties, reducing dust adsorption without affecting touch sensitivity. After being placed in a high temperature and high humidity environment (temperature 60℃, humidity 85%) for 1000 hours, the stress relaxation rate is ≤5%, and the long-term performance is stable. 4. Feasible for mass production and controllable cost: The gradient component preparation adopts an improved version of the existing layered melting equipment, and the secondary ion exchange process does not require the addition of special equipment. The biomimetic coating process is mature. The overall cost is reduced by 40-50% compared to microcrystalline glass, and the mass production yield can reach more than 85%, which is suitable for large-scale production and can be widely used in mid-to-high-end flagship mobile phones. 5. Multifunctional integration: It simultaneously achieves multiple functions such as high hardness, high toughness, oleophobicity, antistatic properties, and stress relaxation resistance, without the need for additional multi-layer structures, thus avoiding the problems of glass interface peeling and decreased touch sensitivity in composite structures.

[0032] Example 1 1.1 Prepare gradient composition glass substrates according to the following weight percentages: The components of the surface layer by weight percentage are: SiO2 70%, Al2O3 13%, Li2O 7%, ZrO2 4%, MgO 1.5%, TiO2 0.5%; The components of the transition layer by weight percentage are: SiO2 71%, Al2O3 11%, Li2O 5%, ZrO2 2%, MgO 2.5%; The core layer is composed of the following components by weight percentage: SiO2 73%, Al2O 39%, Li2O 3%, MgO 4%, and CaO 1.5%.

[0033] Preparation steps: Each component layer is placed in a melting furnace and melted uniformly at 1600-1650℃. Then, through a layered casting process, the surface layer, transition layer, and core layer melts are sequentially bonded, gradually mixed, cooled and shaped, and then ground and polished to obtain a gradient component glass substrate with a thickness of 550μm.

[0034] 1.2 Secondary ion exchange enhancement: 1.2.1 First ion exchange: The glass substrate with the above gradient composition was placed in the first molten salt bath (KNO3 92%, NaNO3 8%) at 390℃ and kept at that temperature for 2.5h; 1.2.2 Intermediate cooling: Under nitrogen atmosphere, cool to room temperature at a rate of 8℃ / min; 1.2.3 Secondary ion exchange: Place in a second molten salt bath (KNO3 88%, LiNO3 12%), at 430℃, and keep at that temperature for 1.2 hours; 1.2.4 Cleaning and Drying: Clean with deionized water 4 times and dry at 110℃ for 1.5h to obtain the tempered glass substrate.

[0035] 1.3. Biomimetic composite coating application: Coating composition (weight percentage): Nano SiO2 35%, Fluorine-modified polyurethane 25%, Polysiloxane 18%, Coupling agent KH-550 7%, Ethanol 15%; Coating steps: Vacuum spraying process is adopted, with a spraying pressure of 0.4MPa, a spraying distance of 18cm, and a coating thickness of 8μm; after spraying, it is cured at 160℃ for 2.5h, and then cooled to room temperature to obtain the final glass cover product.

[0036] 1.4 Performance Testing: The performance of the glass cover plate prepared in this embodiment was tested, and the results are shown in the table below:

[0037] Example 2 The process steps are the same as in Example 1, and the identical parts will not be repeated. Only the parameters are adjusted, as follows: Gradient composition glass substrate composition: The components of the surface layer by weight percentage are: SiO2 68%, Al2O3 15%, Li2O 8%, ZrO 25%, MgO 1%, TiO 21%; The components of the transition layer by weight percentage are: SiO2 70%, Al2O3 12%, Li2O 6%, ZrO2 3%, MgO 2%; The core layer is composed of the following components by weight percentage: SiO2 72%, Al2O3 10%, Li2O 4%, MgO 3%, and CaO 2%.

[0038] Secondary ion exchange: First molten salt bath (KNO3 90%, NaNO3 10%), temperature 380℃, hold for 3h; Second molten salt bath (KNO3 85%, LiNO3 15%), temperature 420℃, hold for 1.5h; Bionic composite coating: 30% nano-SiO2, 30% fluorine-modified polyurethane, 15% polysiloxane, 10% coupling agent KH-550, 10% ethanol, spray thickness 5μm, cured at 150℃ for 3h.

[0039] Performance test results: Mohs hardness 8.5, stress layer depth 100μm, 1.5-meter drop breakage rate 5%, oleophobic layer life 18 months, high temperature and high humidity stress relaxation rate 4.8%, mass production yield 85.2%, unit cost 19.5 yuan / piece, all of which meet the requirements for glass cover plate use.

[0040] Example 3 The process steps are the same as in Example 1, and the identical parts will not be repeated. Only the parameters are adjusted, as follows: Gradient composition glass substrate composition: The components of the surface layer by weight percentage are: SiO2 72%, Al2O3 12%, Li2O 6%, ZrO2 3%, MgO 2%, TiO2 0.5%; The components of the transition layer by weight percentage are: SiO2 73%, Al2O3 10%, Li2O 4%, ZrO2 1%, MgO 3%; The core layer is composed of the following components by weight percentage: SiO2 75%, Al2O3 8%, Li2O 2%, MgO 5%, and CaO 1%.

[0041] Secondary ion exchange: First molten salt bath (KNO3 95%, NaNO3 5%), temperature 400℃, hold for 2 hours; Second molten salt bath (KNO3 90%, LiNO3 10%), temperature 440℃, hold for 1 hour; Bionic composite coating: 40% nano-SiO2, 20% fluorine-modified polyurethane, 20% polysiloxane, 5% coupling agent KH-550, 15% ethanol, spray thickness 10μm, cured at 180℃ for 2h.

[0042] Performance test results: Mohs hardness 9H, stress layer depth 120μm, 1.5-meter drop failure rate 3.8%, oleophobic layer life 24 months, high temperature and high humidity stress relaxation rate 3.9%, mass production yield 87.5%, unit cost 17.2 yuan / piece, and overall performance is better than Examples 1 and 2.

[0043] It should be noted that layered casting, grinding, polishing, etc. are all existing and very mature technologies, and will not be described in detail here.

[0044] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the accompanying drawings are merely examples and do not limit the invention. The advantages of the present invention have been fully and effectively realized. The functional and structural principles of the present invention have been demonstrated and explained in the embodiments; any variations or modifications can be made to the implementation of the present invention without departing from these principles.

Claims

1. A glass cover that balances hardness and toughness, characterized in that, The glass substrate of the glass cover has a gradient layered component structure, comprising a surface layer, a transition layer, and a core layer. The surface layer is the layer exposed during use. The components of the surface layer, by weight percentage, are: SiO2 68-72%, Al2O3 12-15%, Li2O 6-8%, ZrO2 3-5%, MgO 1-2%, and TiO2 0.5-1%. The components of the transition layer, by weight percentage, are: SiO2 70-73%, Al2O3 10-12%, Li2O 4-6%, ZrO2 1-3%, MgO 2-3%; The core layer comprises the following components by weight percentage: SiO2 72-75%, Al2O3 8-10%, Li2O 2-4%, MgO 3-5%, and CaO 1-2%; Specifically, for the components SiO2, Al2O3, Li2O, and MgO, the content of the transition layer is between that of the surface layer and the core layer, exhibiting a gradual change in component content.

2. The glass cover plate that balances hardness and toughness as described in claim 1, characterized in that, The thickness of the surface layer is 50-80 μm, the thickness of the transition layer is 30-50 μm, the thickness of the core layer is 400-500 μm, and the overall thickness of the glass cover is 500-600 μm.

3. The glass cover plate that balances hardness and toughness as described in claim 1, characterized in that, The components of the surface layer by weight percentage are: SiO2 70%, Al2O3 13%, Li2O 7%, ZrO2 4%, MgO 1.5%, TiO2 0.5%; The components of the transition layer by weight percentage are: SiO2 71%, Al2O3 11%, Li2O 5%, ZrO2 2%, MgO 2.5%; The core layer is composed of the following components by weight percentage: SiO2 73%, Al2O3 9%, Li2O 3%, MgO 4%, and CaO 1.5%.

4. The glass cover plate that balances hardness and toughness as described in claim 1, characterized in that, The components of the surface layer by weight percentage are: SiO2 68%, Al2O3 15%, Li2O 8%, ZrO2 5%, MgO 1%, TiO2 1%; The components of the transition layer by weight percentage are: SiO2 70%, Al2O3 12%, Li2O 6%, ZrO2 3%, MgO 2%; The core layer is composed of the following components by weight percentage: SiO2 72%, Al2O3 10%, Li2O 4%, MgO 3%, and CaO 2%.

5. The glass cover plate that combines hardness and toughness as described in claim 1, characterized in that, The components of the surface layer by weight percentage are: SiO2 72%, Al2O3 12%, Li2O 6%, ZrO2 3%, MgO 2%, TiO2 0.5%; The components of the transition layer by weight percentage are: SiO2 73%, Al2O3 10%, Li2O 4%, ZrO2 1%, MgO 3%; The core layer is composed of the following components by weight percentage: SiO2 75%, Al2O3 8%, Li2O 2%, MgO 5%, and CaO 1%.

6. The glass cover plate that combines hardness and toughness as described in any one of claims 1 to 5, characterized in that, The surface of the surface layer is also coated with a biomimetic composite coating, the components of which by weight percentage are: 30-40% nano-SiO2, 20-30% fluorine-modified polyurethane, 15-20% polysiloxane, 5-10% coupling agent, and 10-15% ethanol solvent, wherein the particle size of nano-SiO2 is 20-50nm.

7. A method for preparing a glass cover plate that combines hardness and toughness as described in claim 6, characterized in that, The steps are as follows: S10, prepare gradient component glass cover substrate by placing the surface layer, transition layer and core layer components into a melting furnace and melting them uniformly at 1600-1650℃. Then, through a layered casting process, the surface layer, transition layer and core layer melts are sequentially bonded and gradually mixed. After cooling and forming, the gradient component glass substrate is obtained by grinding and polishing. S20, one-time ion exchange, the obtained gradient component glass substrate is placed in the first molten salt bath, the temperature is 380-400℃, and the temperature is maintained for 2-3 hours; S30, intermediate cooling, slowly cooled to room temperature in an inert gas environment; S40, secondary ion exchange, involves placing a gradient-component glass substrate into a second molten salt bath at a temperature of 420-440℃ for 1-1.5 hours. S50, clean and dry, wash several times in deionized water, dry for 1-2 hours to obtain a reinforced glass substrate.

8. The method for preparing a glass cover plate that balances hardness and toughness as described in claim 7, characterized in that, In step S20, the first molten salt bath is a mixed solution of 90-95% KNO3 and 5-10% NaNO3; in step S40, the second molten salt bath is a mixed solution of 85-90% KNO3 and 10-15% LiNO3.

9. The method for preparing a glass cover plate that balances hardness and toughness as described in claim 7, characterized in that, In step S30, the inert gas is nitrogen, and the cooling rate is 5-10℃ / min; in step S50, the temperature of the drying oven used for drying is 100-120℃.

10. The method for preparing a glass cover plate that balances hardness and toughness as described in claim 7, characterized in that, The process also includes step S60, in which the biomimetic composite coating is applied using a vacuum spraying process, with a spraying pressure of 0.3-0.5 MPa and a spraying distance of 15-20 cm; after spraying, the coating is placed in a curing oven at 150-180°C for 2-3 hours to cure.

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