A drop-resistant and scratch-resistant lithium aluminum silicate glass and its preparation method

Abstract

The present invention belongs to the field of glass manufacturing technology and specifically relates to a drop-resistant and scratch-resistant lithium aluminosilicate glass and a preparation method thereof. The glass comprises the following components, by mass percentage: SiO2 50.0-65.0%, Al2O3 10.0-20.0%, Na2O 2.0-8.0%, K2O 1.0-5.0%, MgO 1.0-5.0%, ZrO2 1.0-5.0%, Li2O 2.0-8.0%, CaO 0.1-2.0%, Y2O3 1.0-5.0%, BaO 0.1-5.0%, and an additive 0.05-0.5%. The additive is one or more of Fe2O3, Co2O3, CuO, and Cr2O3. The mass ratio of BaO to Y2O3 is 1:2-4. The present invention solves the problems of the existing lithium aluminosilicate glass preparation process, such as long melting time, low ion exchange process efficiency, low hardness, low flexural strength, and poor high-temperature stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of glass manufacturing, and in particular relates to a drop-resistant and scratch-resistant lithium aluminum silicate glass and a preparation method thereof. Background Art

[0002] Lithium aluminosilicate glass, an important specialty glass material, is widely used in electronic devices, photovoltaic modules, and safety protection due to its excellent mechanical strength, thermal stability, and chemical durability. The mainstream composition of lithium aluminosilicate glass, by mass percentage, is roughly: 55%-70% SiO2, 12%-23% Al2O3, 13%-16% Na2O, 0%-5% K2O, 2%-6% MgO, 0%-5% B2O3, and 0-2% ZrO2.

[0003] However, mainstream lithium aluminosilicate glass has a narrow controllable composition range, making it difficult to achieve both high hardness, high toughness, and excellent optical properties. Increasing the Al2O3 content leads to a sharp increase in melting temperature and an increased tendency to crystallize. Fluxes (such as B2O3) added to lower the melting temperature significantly reduce the chemical stability of the glass. Existing lithium aluminosilicate glass generally has a Vickers hardness of 6-6.5 GPa, which is difficult to meet the requirements of high-end applications. Its flexural strength is typically in the 300-400 MPa range, leaving room for improvement. Its high-temperature stability is insufficient, with significant performance degradation in long-term high-temperature environments. Furthermore, the existing preparation process typically requires a melting time of 8-12 hours, resulting in long cycles and high energy consumption. The ion exchange process is inefficient, and defects such as streaks and bubbles are prone to appear during the molding process, resulting in a low yield.

[0004] With the rapid development of industries like consumer electronics and new energy, the performance requirements for lithium aluminosilicate glass are becoming increasingly stringent. However, many mobile phone users are still dissatisfied with simple drop resistance, scratch resistance, and ball impact resistance. These traditional performance tests are often inadequate for everyday use. Furthermore, when cover glass produced using traditional chemical strengthening processes is subjected to performance testing, the drop and scratch resistance and performance stability are often suboptimal. Given the shortcomings of existing lithium aluminosilicate glass, there is an urgent need to develop drop- and scratch-resistant lithium aluminosilicate glass and its preparation method. Summary of the Invention

[0005] In response to the above problems, the present invention provides a new type of lithium aluminosilicate glass and a preparation method thereof, which are used to solve the problems of the existing lithium aluminosilicate glass preparation process, such as long melting time, low ion exchange process efficiency, low hardness, low bending strength, and poor high-temperature stability.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] In a first aspect, the present invention provides a drop-resistant and scratch-resistant lithium aluminosilicate glass, which contains the following components, calculated by mass percentage: SiO2 50.0-65.0%, Al2O3 10.0-20.0%, Na2O 2.0-8.0%, K2O 1.0-5.0%, MgO 1.0-5.0%, ZrO2 1.0-5.0%, Li2O 2.0-8.0%, CaO 0.1-2.0%, Y2O3 1.0-5.0%, BaO 0.1-5.0%, and 0.05-0.5% of one or more of Fe2O3, Co2O3, CuO, and Cr2O3. By precisely controlling the BaO and Y2O3 contents, with Y2O3 1.0-5.0% and BaO 0.1-5.0% and a BaO to Y2O3 mass ratio of 1:2-4, the synergistic combination of the two can optimize the melting process and expand functions without sacrificing the core properties of lithium aluminosilicate glass (high strength and high heat resistance), thereby achieving the trinity optimization of "strength-heat resistance-function".

[0008] Furthermore, the lithium aluminosilicate glass has a thickness of 0.2-3.0 mm. SiO2 acts as a network former, constructing a three-dimensional continuous network through [SiO4] tetrahedrons. Its content is positively correlated with the glass transition temperature (Tg) (Tg = 480 + 1.2 × SiO2 mol %). SiO2 is essential for forming the glass skeleton, improving the strength and chemical stability of the glass and enabling it to achieve a lower thermal expansion coefficient. When the SiO2 content is too low, the glass's main network structure is poor, resulting in poor mechanical properties and reduced weather resistance. When the content is too high, the silicon-oxygen skeleton structure is excessively high, resulting in smaller network gaps, which is not conducive to chemical strengthening ion exchange and affects the efficiency of chemical strengthening. Furthermore, excessively high melting temperatures during glass production increase energy consumption and are prone to frequent defects such as bubbles and stones. Therefore, in aluminosilicate glass, the SiO2 content is controlled to be 50%-65%, specifically including but not limited to 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, and 64%. Alumina (Al2O3) is a necessary component to increase the ion exchange capacity of glass, and it can also improve the chemical stability and elastic modulus of glass. When its content is too low, the voids in the network space become smaller, which is not conducive to ion migration and seriously affects the efficiency of chemical strengthening; when its content is too high, the high-temperature viscosity of the glass increases significantly, the melting temperature is too high during the production process, energy consumption increases, and it is also not conducive to controlling defects such as bubbles and stones. Therefore, in aluminosilicate glass, the Al2O3 content is controlled to be 10%-20%, specifically including but not limited to: 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, and 19%. Al2O3 acts as a network intermediate, and the [AlO4] tetrahedron is formed through a charge compensation mechanism (each Al 3+Requires 1 R + ) copolymerizes with the silicon-oxygen network to increase the glass viscosity by 1-2 orders of magnitude at the liquidus temperature; when the ratio is <1, the uncompensated Al 3+ It exists in the network gap in the form of [AlO6] octahedron, resulting in an increase in the thermal expansion coefficient by 20-30×10 -7 / ℃.

[0009] Furthermore, the Na2O+K2O+Li2O content is between 8% and 14%, and the mass ratio of K2O, Na2O, and Li2O is between 1:2-3:1.5-2.5. Within this range, the ion exchange rate can be optimized. The key components of ion exchange, Li2O, form a synergistic effect with Na2O. + (Diffusion coefficient D = 10 -14 m² / s) is responsible for deep diffusion to build stress gradient, Na + (D=10 -16 m² / s) dominates the formation of surface compressive stress. Lithium oxide (Li2O) is an ideal flux and an essential component for ion exchange. + The polarization characteristics of the glass can effectively reduce the high temperature viscosity at high temperature. Since the present invention uses a mixed molten salt of NaNO3 and KNO3 in the strengthening process, the glass is + With Na in molten salt + Ion exchange can quickly increase the depth of the compressive stress layer, giving the glass superior mechanical impact resistance. Therefore, the Li2O content in aluminosilicate glass is controlled at 2%-8%. Sodium oxide (Na2O), another major fluxing agent, is essential for ion exchange and significantly lowers the melting temperature of aluminosilicate glass. If its content is too low, not only will the glass's melting properties deteriorate, but the stress values ​​in the K-Na ion exchange layer will be too low, leading to poor microhardness, increased cracking, and decreased drop resistance. If its content is too high, the glass's network structure will deteriorate, reducing the stability of its mechanical and thermal properties and chemical durability. Therefore, the Na2O content in aluminosilicate glass is controlled at 2%-8%. Potassium oxide (KO) improves the glass's melting properties. However, if its content is too high, the glass's network structure will be significantly weakened, reducing its thermal stability. Therefore, the KO content in aluminosilicate glass is controlled at 1%-5%. Zirconia (ZrO2) can improve the chemical stability and ion exchange performance of glass, increase the surface hardness of glass, and increase the pressure required for glass to form cracks, making the glass more resistant to scratches and drops. Only a small amount of ZrO2 is enough to meet these requirements, so it is an essential component. However, too much ZrO2 will significantly increase the melting temperature of glass and cause defects such as stones, which will have an adverse effect on production. When the ZrO2 addition is controlled at 0.5-2%, Zr 4+The field intensity effect is used to suppress phase separation, which increases the microhardness by 10-15%. When the content is greater than 3%, the melt viscosity at high temperature increases, which causes the clarification temperature to increase by 50-80°C. 2+ As alkaline earth metal ions, they can provide free oxygen (O 2- ), and the aluminum oxide tetrahedron ([AlO4] 5- ) combines, neutralizes the charge imbalance, stabilizes the glass network structure, Ba 2+ The larger ionic radius (1.35Å) can hinder the orderly arrangement of the aluminosilicate network and reduce the risk of crystallization, especially at high Al2O3 content (>20%). BaO can significantly reduce the melt viscosity. At 1500℃, the viscosity decreases by about 10% for every 1% increase of BaO. It improves the melting performance of high-aluminum glass (Al2O3 content 25-30%). The melting temperature of high-aluminum glass containing 3% BaO can be reduced by 50-80℃. The addition of BaO can reduce the thermal expansion coefficient of glass. Adding 2% BaO can increase the CTE from 5.2×10 -6 / ℃ dropped to 4.8×10 -6 / ℃ (25-300℃ range). 3+ (ionic radius 0.90Å) as a high field strength cation, preferentially occupies the interstitial position of the aluminosilicate network, forms a strong bond with the [AlO4]⁻ tetrahedron (YO bond energy is about 600 kJ / mol), stabilizes the glass network structure, Y2O3 can significantly increase the crystallization activation energy of the glass, inhibit the precipitation of mullite (3Al2O3·2SiO2) and other crystalline phases in high alumina glass (Al2O3 content 25-30%), and the addition of 1% Y2O3 can increase the crystallization peak temperature from 980℃ to 1050℃ (DSC test), Y2O3 induces microcrystalline phases (such as YAG: Y3Al5O 12 ) formation, and improve toughness through crack deflection mechanism: adding 2% Y2O3 can increase the fracture toughness (K1C) from 1.2 MPa·m 1 / 2 Increased to 1.8 MPa·m 1 / 2 Y2O3 reduces the melt viscosity (η) at high temperature (>1400℃) and improves the formability of high-aluminum glass: at 1550℃, the viscosity of glass containing 1% Y2O3 decreases from 10 3 Pa·s is reduced to 8×10 2 Pa·s. Magnesium oxide (MgO) can reduce the viscosity of glass at high temperatures, promote the melting and clarification of glass, enhance the stability of the glass network space at low temperatures, have a good repair effect on the gaps in the glass silicon-aluminum-oxygen network structure, reduce the thermal expansion coefficient of glass to a certain extent, and increase the low-temperature viscosity of glass and the strain point of glass. It is an essential component. However, it has a certain inhibitory effect on ion exchange. When the content is too high, MgO will 2+CaO significantly impedes the ion exchange capacity of glass, significantly reducing the depth of the compressive stress layer for K-Na exchange. CaO acts similarly to MgO and can enhance the stability of the glass network at low temperatures, but it also significantly hinders ion exchange, making it a non-essential component. Alkaline earth metal oxides (MgO, CaO) stabilize the strain point of glass at 520-550°C through a "mixed alkaline earth effect," while simultaneously increasing the temperature difference between the softening point and annealing point to 150-200°C, significantly improving hot bendability.

[0010] Furthermore, the novel lithium aluminosilicate glass contains the following components, in mass percentage: SiO2 60.0-64.0%, Al2O3 18.0-20.0%, Na2O 4.0-6.0%, K2O 1.0-2.5%, MgO 1.0-2.0%, ZrO2 1.0-3.0%, Li2O 3.0-5.0%, CaO 0.1-1.0%, Y2O3 1.0-2.0%, BaO 0.1-1.0%, and 0.05-0.5% of one or more of Fe2O3, Co2O3, CuO, and Cr2O3.

[0011] In a second aspect, the present invention provides a method for preparing the lithium aluminosilicate glass according to the first aspect of the present invention, using a float process, and specifically comprising the following steps:

[0012] (1) Weigh the raw materials according to the formula ratio, and stir and mix the raw materials thoroughly to obtain a batch mixture;

[0013] (2) subjecting the batch mixture to a high-temperature melting treatment and introducing ultrasonic treatment at the end of the melting treatment;

[0014] (3) Casting the molten mixture into a mold and annealing it to obtain a glass sheet;

[0015] (4) The glass sheet is chemically strengthened in two steps to obtain the product lithium aluminum silicate glass.

[0016] Furthermore, the melting temperature is 1500-1600°C, and the melting time is 6-8 h.

[0017] Furthermore, the ultrasonic wave is 20-40 kHz, and ultrasonic treatment is performed for 30 minutes at the end of the melting process to reduce the generation of bubbles.

[0018] Furthermore, in the two-step strengthening, the first step is strengthening using a mixed salt of sodium nitrate and potassium nitrate, and the second step is strengthening using pure potassium nitrate. The strengthening temperature is 400-450° C. and the strengthening time is 1-8 hours.

[0019] In the glass strengthening process, when potassium salts (such as potassium nitrate) and / or sodium salts (such as sodium nitrate) are used for chemical strengthening (ion exchange), each salt has different effects and advantages. Sodium nitrate and potassium nitrate form a low-temperature eutectic system after mixing, forming a compressive stress layer on the surface, reducing process energy consumption while preventing glass deformation due to high temperature. The mixed salt optimizes the ion exchange kinetics, making the stress layer deeper and improving impact resistance and bending resistance. Secondary strengthening uses pure KNO3 molten salt, K + The diffusion ability is stronger and can penetrate deeper into the glass network structure. + The higher the concentration, the better the ion exchange efficiency, and the deeper compressive stress can more effectively prevent crack propagation.

[0020] Furthermore, in the mixed salt of sodium nitrate and potassium nitrate, the mass ratio of sodium nitrate to potassium nitrate is 1:1-3.

[0021] Beneficial effects

[0022] (1) The aluminosilicate tempered glass provided by the present invention optimizes the mechanical properties of the aluminosilicate tempered glass by rationally adjusting the composition of the aluminosilicate glass (Na2O, K2O, Li2O, BaO, Y2O3, etc.), and has high hardness, high toughness, and resistance to drop and scratches while taking into account excellent optical properties. This effectively alleviates the problem of the existing products being prone to banded scratches, and at the same time enhances the drop resistance, surface scratch resistance, and chemical stability of the aluminosilicate glass that is resistant to drop and scratches.

[0023] (2) The preparation method of the present invention reduces energy consumption through layered melting and ultrasonic treatment, and improves strength by adjusting the specific operations and parameters of the strengthening steps. Compared with traditional processes, the present invention significantly shortens the melting process time to only 4-6 hours, saving energy consumption. In addition, the process of the present invention has fewer defects such as bubbles and a high yield rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0025] Figure 1 This is a dark field scanning transmission microscope image of the lithium aluminum silicate glass prepared in Example 1 of the present invention;

[0026] Figure 2 This is a bright field scanning transmission microscope image of the lithium aluminum silicate glass prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the technical solution, the present invention is described in detail below in conjunction with embodiments. The description in this section is only exemplary and explanatory and should not have any limiting effect on the scope of protection of the present invention.

[0028] Example 1

[0029] SiO2 63.0%, Al2O3 19.0%, Li2O 4.00%, MgO 1.70%, CaO 0.18%, ZrO2 2.50%, K2O2.00%, Na2O 5.40%, Fe2O3 0.09%, Y2O3 1.60%, BaO 0.53%.

[0030] (1) Weigh the raw materials according to the formula ratio and stir them thoroughly to obtain a batch mixture.

[0031] (2) The batch mixture was melted at 1550°C for 6 h; at the end of the melting treatment, ultrasonic treatment was introduced for 30 minutes; the ultrasonic wave was 20-40 kHz.

[0032] (4) Annealing treatment: the annealing temperature is 580℃ and the time is 1.5 h.

[0033] (5) Strengthening treatment: first immerse the lithium aluminum silicate glass in a mixed salt bath of molten sodium nitrate and potassium nitrate (the mass ratio of sodium nitrate to potassium nitrate is 1:1) at a temperature of 415°C for 150 minutes; then immerse it in a mixed salt bath of molten sodium nitrate and potassium nitrate at a temperature of 420°C for 150 minutes.

[0034] In Examples 2-6, the content of each component was adjusted to prepare a novel lithium aluminum silicate glass, the specific composition of which is shown in Table 1:

[0035]

[0036] Comparative Example 1: Compared with Example 1, no ultrasonic assistance was used.

[0037] Comparative Example 2: Compared with Example 1, only the first strengthening was used, and the strengthening time was 300 min.

[0038] Comparative Example 3: Compared with Example 1, only the second strengthening was used, and the strengthening time was 300 min.

[0039] Comparative Example 4: Compared with Example 1, only sodium nitrate was used in the second strengthening process.

[0040] Comparative Example 5: Compared with Example 1, the ratio of barium oxide to yttrium oxide is 1:1, and the other contents remain unchanged.

[0041] Comparative Example 6: Compared with Example 1, the ratio of barium oxide to yttrium oxide is 1:5, and the other parameters remain unchanged.

[0042] After testing, the performance parameters of Examples 1-6 of the present invention and Comparative Examples 1-6 are shown in Table 2 and Table 3, respectively.

[0043] Table 2 Performance parameter test values ​​of Examples 1-6

[0044]

[0045] Table 3 Performance parameter test values ​​of comparative examples 1-6

[0046]

[0047] This optimal implementation method has been verified through pilot testing, with a product yield of 95.5% and comprehensive performance indicators exceeding those of existing commercial lithium aluminum silicate glass products, making it valuable for industrial promotion.

[0048] It should be noted that, in this article, the terms: include, contain and any other variations are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also other elements that are not explicitly listed, or also includes elements that are inherent to such process, method, article or device. Specific examples are used herein to illustrate the principles and implementation methods of the technical solution of the present invention. The above examples are only used to help understand the method of the present invention and its core idea. The above is only a preferred embodiment of the present invention. It should be pointed out that due to the limitations of textual expression, there are objectively infinite specific structures. For ordinary technicians in this technical field, without departing from the principles of the present invention, several improvements, modifications or changes can be made, and the above technical features can be combined in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the concept and technical solution of the present invention to other occasions without improvement, should be regarded as the scope of protection of the present invention.

Claims

1. A drop-resistant and scratch-resistant lithium aluminum silicate glass, characterized in that: The invention comprises the following components in percentage by mass: SiO2 50.0-65.0%, Al2O3 10.0-20.0%, Na2O 2.0-8.0%, K2O 1.0-5.0%, MgO 1.0-5.0%, ZrO2 1.0-5.0%, Li2O 2.0-8.0%, CaO 0.1-2.0%, Y2O3 1.0-5.0%, BaO 0.1-5.0%, and additives 0.05-0.5%; the additives are one or more of Fe2O3, Co2O3, CuO, and Cr2O3; wherein the mass ratio of BaO to Y2O3 is 1:2-4; The method for preparing the lithium aluminosilicate glass comprises the following steps: (1) Weigh the raw materials according to the formula ratio, and stir and mix the raw materials thoroughly to obtain a batch mixture; (2) subjecting the batch mixture to a high-temperature melting treatment and introducing ultrasonic treatment at the end of the melting treatment; (3) Casting the molten mixture into a mold and annealing it to obtain a glass sheet; (4) Chemically strengthening the glass sheet in two steps to obtain lithium aluminum silicate glass; The ultrasonic wave is 20-40 kHz, and the ultrasonic treatment is carried out for 30 minutes; The two-step strengthening is as follows: the first step is strengthening using a mixed salt of sodium nitrate and potassium nitrate, and the second step is strengthening using pure potassium nitrate. The strengthening temperature is 400-450° C. and the strengthening time is 1-8 hours.

2. The lithium aluminosilicate glass according to claim 1, wherein Calculated in mass percentage, it contains the following components: SiO2 60.0-64.0%, Al2O3 18.0-20.0%, Na2O 4.0-6.0%, K2O 1.0-2.5%, MgO 1.0-2.0%, ZrO2 1.0-3.0%, Li2O 3.0-5.0%, CaO 0.1-1.0%, Y2O3 1.0-2.0%, BaO 0.1-1.0%, and additives 0.05-0.5%; among which, the mass ratio of BaO to Y2O3 is 1:2-4.

3. The lithium aluminosilicate glass according to claim 1, wherein The thickness of the lithium aluminosilicate glass is 0.2-3.0 mm.

4. The lithium aluminosilicate glass according to claim 1, wherein The total content of Na2O, K2O and Li2O is 8%-14%, and the mass ratio of K2O, Na2O and Li2O is 1:2-3:1.5-2.

5.

5. The lithium aluminosilicate glass according to claim 4, characterized in that n(R2O) / n(Al2O3)<1, where R is Na, K, or Li.

6. The method for preparing lithium aluminosilicate glass according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Weigh the raw materials according to the formula ratio, and stir and mix the raw materials thoroughly to obtain a batch mixture; (2) subjecting the batch mixture to a high-temperature melting treatment and introducing ultrasonic treatment at the end of the melting treatment; (3) Casting the molten mixture into a mold and annealing it to obtain a glass sheet; (4) Chemically strengthening the glass sheet in two steps to obtain lithium aluminum silicate glass; The ultrasonic wave is 20-40 kHz, and the ultrasonic treatment is carried out for 30 minutes; The two-step strengthening is as follows: the first step is strengthening using a mixed salt of sodium nitrate and potassium nitrate, and the second step is strengthening using pure potassium nitrate. The strengthening temperature is 400-450° C. and the strengthening time is 1-8 hours.

7. The preparation method according to claim 6, wherein The melting temperature is 1500-1600°C, and the melting time is 6-8h.

Images