Weather-resistant microcrystalline glass, preparation method thereof, glass device, cover plate glass and electronic equipment

Abstract

The application discloses weather-resistant microcrystalline glass and a preparation method thereof, a glass device, a cover plate glass and electronic equipment. By setting components in raw materials, a target crystal phase is obtained. After two chemical strengthening, the microcrystalline glass surface has a certain sodium and potassium, a surface compressive stress layer is established, and the mechanical properties are enhanced. However, sodium and potassium are also the source of affecting the performance of the microcrystalline glass under high-temperature and high-humidity conditions. In the application, a certain thickness of the surface of the microcrystalline glass is removed after the chemical strengthening process. On the one hand, the sodium and potassium are as low as possible, so as to reduce the risk of hydrolysis under high-temperature and high-humidity aging conditions and then cause the mechanical properties to decrease as much as possible. Meanwhile, the removal thickness is controlled, so as to maintain the mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of microcrystalline glass, specifically relating to a weather-resistant microcrystalline glass and its preparation method, glass devices, cover glass, and electronic devices. Background Technology

[0002] Lithium aluminum silicon (LAS) glass-ceramics have been widely used in fields such as smart terminal cover plates, electronic displays, automotive displays and wearable devices due to their excellent thermal stability, high mechanical strength and the ability to further enhance strength through chemical strengthening.

[0003] To achieve higher mechanical strength, current technologies generally employ microcrystalline glass substrates with high lithium content and high lithium disilicate crystalline phase content, combined with a two-step ion exchange process to introduce higher central tensile stress and a deep compressive stress layer. The first step of this process involves Na... + -Li + Exchange, using Na + For Li + The rapid, deep displacement establishes a relatively deep stress layer, but due to the limited difference in ionic radii, the surface compressive stress generated in this step is relatively low; the second step is K + -Na + Exchange, using K + with Na + A larger radius difference creates an extremely high peak compressive stress on the outermost layer of the material, thereby enhancing its scratch and impact resistance.

[0004] However, research has found that after the aforementioned chemical strengthening, a "non-ideal layer" forms on the glass surface. The presence of this layer mainly stems from the following defects: 1) surface contamination caused by salt bath residue; 2) surface Na+. + / K + Excessive concentration leads to localized structural relaxation and stress relaxation; 3) Micro-defects such as scratches and microcracks left over from the processing. This non-ideal layer must be removed through a re-polishing (i.e., surface removal) process to expose the truly dense, stress-saturated, and structurally stable subsurface layer. In actual production, controlling the amount of re-polishing removal faces a dilemma: if the removal amount is too small, the non-ideal layer remains, which will become the starting point for ion migration and microcrack initiation under high temperature and humidity conditions, leading to a decrease in reliability; if the removal amount is too large, the stress layer will be excessively thinned, causing the glass to lose the effective protection of the strengthening layer, resulting in deterioration of mechanical properties. Especially for microcrystalline glass systems, factors such as crystallinity, crystal phase type, and distribution further increase the complexity of removal amount control. How to determine the optimal re-polishing removal thickness for different microcrystalline glass systems after chemical strengthening has become an urgent technical problem to be solved. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a weather-resistant microcrystalline glass, its preparation method, glass devices, cover glass, and electronic devices. The overall concept of this invention is as follows: By setting the components in the raw materials, a target crystalline phase is obtained. After two chemical strengthening processes, the surface of the microcrystalline glass has a certain amount of sodium and potassium, establishing a surface compressive stress layer to enhance its mechanical properties. However, sodium and potassium are also sources that affect the performance of microcrystalline glass under high temperature and high humidity conditions. This invention removes a certain thickness from the surface of the microcrystalline glass after the chemical strengthening process. On the one hand, this minimizes the amount of sodium and potassium to reduce the risk of hydrolysis under high temperature and high humidity aging conditions, which could lead to a decline in mechanical properties. On the other hand, the thickness of the removal is controlled to maintain mechanical properties. The specific technical solution of this invention is as follows:

[0006] A method for preparing weather-resistant glass-ceramics includes the following steps:

[0007] Step 1: Melting. Prepare raw materials in a certain proportion, mix them evenly, melt the evenly mixed raw materials into a mold, and then anneal them to obtain the glass precursor.

[0008] Step 2: Crystallization. The glass precursor obtained in Step 1 is subjected to crystallization heat treatment. After cooling, it is shaped, sliced, CNC machined, and polished. The purpose of polishing in this step is to completely remove all sources that may cause breakage.

[0009] Step 3: Chemical strengthening. The microcrystalline glass obtained in Step 2 undergoes ion exchange treatment, followed by repolishing. The chemically strengthened microcrystalline glass is then cleaned with a neutral glass cleaner to obtain the finished product. The repolishing requirements in this step are: double-sided polishing of the microcrystalline glass product, with single-sided polishing removing a thickness d, where d = k × (1 - Xc) × DOL-0, in µm, where k = 0.04-0.51, Xc is the crystallinity of the microcrystalline glass, and DOL-0 is the ion exchange depth; the thickness removed by double-sided polishing is 2d. Xc, the crystallinity of the microcrystalline glass, can be calculated by fitting the XRD test results; the DOL-0 value can be measured using a SLP-2000 glass surface stress meter. The repolishing process involves using white leather strips, carpets, or sponges as polishing media, combined with a polishing slurry formulated with cerium oxide or silica. The particle size of the cerium oxide or silica in the polishing slurry must meet the requirements of D50 ≤ 1 micrometer and D90 ≤ 2 micrometers. By adjusting parameters such as polishing pressure and rotation speed, a stable and predictable material removal rate is achieved, and the repolishing accuracy is controlled through real-time measurement and feedback. Preferably, the polishing wheel used in repolishing is an epoxy resin polishing wheel; the abrasive is white abrasive with a hardness of 45-75HA; the upper abrasive disc rotation speed is 5-20 rpm, and the lower abrasive disc rotation speed is 10-25 rpm; the abrasive powder concentration is 1.1-1.2 g / cm³. 3The pressure of a single glass sheet is 5-10 kg. In some embodiments, the crystallinity of the weather-resistant microcrystalline glass is 60% or 61% or 62% or 63% or 64% or 65% or 66% or 67% or 68% or 69% or 70% or 71% or 72% or 73% or 74% or 75% or 76% or 77% or 78% or 79% or 80% or 81% or 82% or 83% or 84% or 85% or 86% or 87% or 88% or 89% or 90%, or a value within the range of any two of the above specific values ​​as endpoints.

[0010] In some embodiments, at a thickness of 0.6 mm, the DOL-0 value of the weather-resistant microcrystalline glass is 105µm, 106µm, 107µm, 108µm, 109µm, 110µm, 111µm, 112µm, 113µm, 114µm, 115µm, 116µm, 117µm, 118µm, 119µm, 120µm, 121µm, 122µm, 123µm, 124µm, 125µm, 126µm, 127µm, 128µm, 129µm, or 130µm, or a value within the range of any two of the above specific values ​​as endpoints.

[0011] Further, k = 0.04-0.51, preferably 0.07-0.40. In some embodiments, k is 0.04 or 0.05 or 0.06 or 0.07 or 0.08 or 0.09 or 0.1 or 0.12 or 0.13 or 0.14 or 0.15 or 0.16 or 0.17 or 0.18 or 0.19 or 0.2 or 0.21 or 0.22 or 0.23 or 0.24 or 0.25 or 0.26 or 0.27 or 0.28 or 0.29 or 0.3 or 0.31 or 0.32 or 0.33 or 0.34 or 0.35 or 0.36 or 0.37 or 0.38 or 0.39 or 0.4 or 0.41 or 0.42 or 0.43 or 0.44 or 0.45 or 0.46 or 0.47 or 0.48 or 0.49 or 0.5 or 0.51 or a value within the range of values ​​formed by any two of the above specific values ​​as endpoints.

[0012] The removal of thickness d must be within a certain range to achieve the following: 1. Grinding away the non-ideal surface layer; 2. Exposing a dense and stable stress matrix; 3. Without damaging the effective strengthening layer. Lithium disilicate glass-ceramics have a two-phase structure consisting of a crystalline phase and a glassy phase: the crystalline phase hardly participates in ion exchange, Na... + K⁺ cannot enter; while the glassy phase is the main site of ion exchange, Na⁺... +K⁺ enters to form compressive stress. The physical meaning of (1-Xc) is the proportion of glass phase that can undergo effective ion exchange. The higher the crystallinity, the less exchangeable phase there is, and thus the total stress is limited; the lower the crystallinity, the more glass phase there is, and thus the overall strength may decrease.

[0013] The ion exchange depth DOL-0 determines the thickness of the stress layer and the safety margin for re-polishing. A larger DOL-0 results in a thicker stress layer and a greater capacity for re-polishing; a smaller DOL-0 means even slight re-polishing will damage the stress matrix. In this application, the three parameters are multiplied to obtain the effective stress layer thickness provided by the exchangeable phase. The key to resisting high-temperature and high-humidity aging lies in using the stress generated by the limited exchangeable phase precisely in the most resistant subsurface layer. Why do samples satisfying this relationship exhibit good aging resistance? Because the damage path of high-temperature and high-humidity aging is: water molecules penetrating the surface activate Na⁺ / K⁺ migration, leading to precipitation / hydrolysis, stress relaxation, microcrack initiation, and ultimately, strength reduction. The starting point of damage is always the surface layer. When the removal amount d satisfies: d = k × (1-Xc) × DOL-0, it means:

[0014] 1. The non-ideal layer has been completely removed—the surface is free of contamination, relaxation, and micro-defects;

[0015] 2. What is exposed is a dense, sodium and potassium stable, stress-saturated subsurface layer—this layer is determined by the proportion of exchangeable glass phases and the depth of exchange.

[0016] 3. The effective stress layer has not been excessively ground away—it still has sufficient thickness to resist subsequent aging.

[0017] Preferably, the raw materials in step 1 consist of: SiO2 55-75 mol%, Al2O3 0.5-4 mol%, ZrO2 2-10 mol%, Li2O 20-35 mol%, P2O5 0.5-3 mol%, Na2O 0-3 mol%, K2O 0-0.5 mol%, CaO 0-3 mol%, BaO 0-3 mol%, Sb2O3 0-0.6 mol%, SnO2 0-0.6 mol%, and RE2O3 0-3 mol%, wherein RE2O3 is one or more of La2O3, Y2O3, Sm2O3, Eu2O3, and Yb2O3. In some embodiments, SiO2 The values ​​are 55 mol%, 56 mol%, 57 mol%, 58 mol%, 59 mol%, 60 mol%, 61 mol%, 62 mol%, 63 mol%, 64 mol%, 65 mol%, 66 mol%, 67 mol%, 68 mol%, 69 mol%, 70 mol%, 71 mol%, 72 mol%, 73 mol%, 74 mol%, or 75 mol%, or values ​​within any two of the above specific values ​​as endpoints; Al2O3 is 0.5 mol%, 1 mol%, 1.5 mol%, 2 mol%, 2.5 mol%, 3 mol%, 3.5 mol%, or 4 mol%, or values ​​within any two of the above specific values ​​as endpoints; ZrO2 is 2 mol%, 3 mol%, 4 mol%, 5 mol%, 6 mol%, 7 mol%, 8 mol%, 9 mol%, or 10 mol%, or values ​​within any two of the above specific values ​​as endpoints; Li2O The values ​​are 20 mol%, 21 mol%, 22 mol%, 23 mol%, 24 mol%, 25 mol%, 26 mol%, 27 mol%, 28 mol%, 29 mol%, 30 mol%, 31 mol%, 32 mol%, 33 mol%, 34 mol%, or 35 mol%, or values ​​within the range defined by any two of the above specific values ​​as endpoints; P₂O₅ is 0.5 mol%, 1 mol%, 1.5 mol%, 2 mol%, 2.5 mol%, or 3 mol%, or values ​​within the range defined by any two of the above specific values ​​as endpoints; Na₂O is 0, 0.5 mol%, 1 mol%, 1.5 mol%, 2 mol%, 2.5 mol%, 3 mol%, 3.5 mol%, 4 mol%, 4.5 mol%, 5 mol%, 5.5 mol%, 6 mol%, 6.5 mol%, or 7 mol%, or values ​​within the range defined by any two of the above specific values ​​as endpoints; K₂O It is 0.01 mol%, 0.05 mol%, 0.1 mol%, 0.15 mol%, 0.2 mol%, or 0.25 mol%, or 0.3 mol%, or 0.35 mol%, or 0.4 mol%, or 0.45 mol%, or 0.5 mol%, or values ​​within the range defined by any two of the above specific values ​​as endpoints; CaO is 0, 0.5 mol%, or 1 mol%, or 1.5 mol%, or 2 mol%, or 2.5 mol%, or 3 mol%, or values ​​within the range defined by any two of the above specific values ​​as endpoints; BaO is 0, 0.5 mol%, or 1 mol%, or 1.5 mol%, or 2 mol%, or 2.5 mol%, or 3 mol%, or values ​​within the range defined by any two of the above specific values ​​as endpoints; Sb₂O₃ is 0, 0.1 mol%, or 0.2 mol%, or 0.3 mol%, or 0.4 mol%, or 0.5 mol%, or 0.6 mol%, or values ​​within the range defined by any two of the above specific values ​​as endpoints; Sn O2 is 0, 0.1 mol%, 0.2 mol%, 0.3 mol%, 0.4 mol%, 0.5 mol%, or 0.6 mol%, or a value within the range defined by any two of the above specific values ​​as endpoints; RE2O3 is 0, 0.01 mol%, 0.02 mol%, 0.03 mol%, 0.04 mol%, 0.05 mol%, 0.06 mol%, 0.07 mol%, 0.08 mol%, 0.09 mol%, 0.1 mol%, 0.2 mol%, 0.3 mol%, 0.4 mol%, 0.5 mol%, 1 mol%, 1.5 mol%, 2 mol%, 2.5 mol%, or 3 mol%, or a value within the range defined by any two of the above specific values ​​as endpoints, wherein RE2O3 is one or more of La2O3, Y2O3, Sm2O3, Eu2O3, and Yb2O3.

[0018] Preferably, in step 2, the crystallization adopts a two-stage heat treatment process, with the nucleation treatment temperature being 500-600℃ and the holding time being 2-10h; and the crystallization treatment temperature being 680-760℃ and the holding time being 1-4h.

[0019] Preferably, the chemical strengthening in step 3 involves two chemical strengthening processes: the first chemical strengthening uses a molten salt mixture of 20-80 wt% sodium nitrate, 20-80 wt% potassium nitrate, and 0.04-0.3 wt% lithium nitrate at 400-530°C for 2-8 hours; the second chemical strengthening uses a molten salt mixture of 0-30 wt% sodium nitrate, 70-100 wt% potassium nitrate, and 0-0.05 wt% lithium nitrate at 350-500°C for 20-120 minutes. In some embodiments, during the first chemical strengthening, the sodium nitrate content in the strengthening molten salt is 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, or 80 wt%, or a value within a range defined by any two of the above specific values ​​as endpoints; the potassium nitrate content is 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, or 80 wt%, or a value within a range defined by any two of the above specific values ​​as endpoints. The lithium nitrate content is 0.04 wt%, 0.06 wt%, 0.08 wt%, 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt%, or 0.3 wt%, or a value within the range defined by any two of the above specific values ​​as endpoints; during the second chemical strengthening, the sodium nitrate content in the strengthening molten salt is 0 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, or 10 wt%. The potassium nitrate content is 70 wt%, 80 wt%, or 9 wt% (t%), or 11 wt%, or 12 wt%, or 13 wt%, or 14 wt%, or 15 wt%, or 16 wt%, or 17 wt%, or 18 wt%, or 19 wt%, or 20 wt%, or 21 wt%, or 22 wt%, or 23 wt%, or 24 wt%, or 25 wt%, or 26 wt%, or 27 wt%, or 28 wt%, or 29 wt%, or 30 wt%, or a value within the range of any two of the above specific values ​​as endpoints. The lithium nitrate content is 0 wt%, 91 wt%, 92 wt%, 93 wt%, 94 wt%, 95 wt%, 96 wt%, 97 wt%, 98 wt%, 99 wt%, or 100 wt%, or a value within the range of any two of the above specific values ​​as endpoints.

[0020] A weather-resistant microcrystalline glass is prepared by the aforementioned method.

[0021] Furthermore, the main crystal phase of the weather-resistant glass-ceramics is lithium disilicate, or lithium disilicate and spodumene, with a crystallinity of 60-90%; the content of Na2O in the 0-30μm thickness of the surface of the weather-resistant glass-ceramics is ≤7wt%, and 0<K2O content ≤0.8wt%; the composition of the weather-resistant glass-ceramics is: SiO2 55-75mol%, Al2O3 0.5-4mol%, ZrO2 2-10mol%, Li2O 20-35mol%, P2O5 0.5-3mol%, Na2O 0-7mol%, K2O 0.01-0.5mol%, CaO 0-3mol%, BaO 0-3mol%, Sb2O3 0-0.6mol%, SnO2 0-0.6mol% and RE2O3 0-3mol%, where RE2O3 is one or more of La2O3, Y2O3, Sm2O3, Eu2O3 and Yb2O3. In the present invention, the main crystal phase refers to the crystal phase having a higher weight content (or also called weight percentage, mass percentage) than other crystal phases present in the glass-ceramics.

[0022] In some embodiments, the Na₂O content is 0 or 1 wt%, or 1.2 wt%, or 1.4 wt%, or 1.6 wt%, or 1.8 wt%, or 2 wt%, or 2.2 wt%, or 2.4 wt%, or 2.6 wt%, or 2.8 wt%, or 3 wt%, or 3.2 wt%, or 3.4 wt%, or 3.6 wt%, or 3.8 wt%, or 4 wt%, or 4.1 wt%, or 4.2 wt%, or 4.3 wt%, or 4.4 wt%, or 4.5 wt%, or 4.6 wt%, or 4.7 wt%, or 4.8 wt%, or 4.9 wt%, or 5 wt%, or 5.1 wt%, or 5.2 wt%, or 5.3 wt%, or 5.4 wt%, or 5.5 wt%, or 5.6 wt%, or 5.7 wt%, or 5.8 wt%. The content of K₂O is 0.01wt%, 0.02wt%, 0.03wt%, 0.04wt%, 0.05wt%, 0.06wt%, 0.07wt%, 0.08wt%, 0.09wt%, 0.1wt%, 0.11wt%, 0.12wt%, 0.13wt%, 0.14wt%, 0.15wt%, 0.16wt%, or 0.17wt%. % or 0.18wt% or 0.19wt% or 0.2wt% or 0.21wt% or 0.22wt% or 0.23wt% or 0.24wt% or 0.25wt% or 0.26wt% or 0.27wt% or 0.28wt% or 0.29wt% or 0.3wt% or 0.31wt% or 0.32wt% or 0.33wt% or 0.34wt% or 0.35wt% or 0.36wt% or 0.37wt% or 0.38wt% or 0.39wt% or 0.4wt% or 0.41wt% or 0.42wt% or 0.43wt% or 0.44wt% or 0.45wt% or 0.46wt% or 0.47wt% or 0.48wt% or 0.49wt% or 0.5wt% or 0.51wt% or 0.52wt% or 0.53wt% or 0.54wt% or 0.55wt% or 0.56wt% or 0.57wt% or 0.58wt% or 0.59wt% or 0.6wt% or 0.61wt% or 0.62wt% or 0.63wt% or 0.64wt% or 0.65wt% or 0.66wt% or 0.67wt% or 0.68wt% or 0.69wt% or 0.7wt% or 0.71wt% or 0.72wt% or 0.73wt% or 0.74wt% or 0.75wt% or 0.76wt% or 0.77wt% or 0.78wt% or 0.79wt% or 0.8wt%, or a value falling within the range defined by any two of the above specific values ​​as endpoints.

[0023] Furthermore, after being placed at 85°C and 85%RH for 240 hours, the average failure height of the weather-resistant microcrystalline glass when dropped by a 150g steel ball decreases by no more than 20% compared to the initial value before aging, and the drop height after the aging test is not less than 0.8 meters. In some embodiments, the drop height after the aging test is 0.8 meters, 0.9 meters, 1 meter, 1.1 meters, 1.2 meters, 1.3 meters, 1.4 meters, or 1.5 meters, or a value within the range of any two of the above specific values ​​as endpoints.

[0024] A glass device comprising the aforementioned weather-resistant microcrystalline glass.

[0025] A cover glass comprising the aforementioned weather-resistant microcrystalline glass.

[0026] An electronic device comprising the aforementioned weather-resistant microcrystalline glass.

[0027] This invention first determines the target crystalline phase and crystallinity by setting the components in the raw materials. After two chemical strengthening processes, the surface of the glass-ceramic has a certain amount of sodium and potassium, establishing a surface compressive stress layer and enhancing its mechanical properties. However, sodium and potassium are also sources that affect the performance of the glass-ceramic under high temperature and high humidity conditions. This invention further removes a certain thickness from the surface of the glass-ceramic after the chemical strengthening process. On the one hand, this minimizes the amount of sodium and potassium to reduce the risk of hydrolysis and subsequent decline in mechanical properties under high temperature and high humidity aging conditions; on the other hand, it controls the thickness of the removed material to maintain mechanical properties. The beneficial technical effects achieved are as follows: This method allows for reasonable control of the removed thickness. Weather-resistant glass-ceramics prepared by this method, after being placed at 85°C and 85%RH for 240 hours, with a thickness of 0.6mm, has an average failure height ≥0.8m when dropped by a 150g steel ball, which is reduced by no more than 20% compared to the initial value before aging. Attached Figure Description

[0028] Figure 1 These are XRD test results of the microcrystalline glass prepared in Examples 1 and 5 of this invention;

[0029] Figure 2 This is a SEM image of the microcrystalline glass prepared in Example 1 of this invention after etching with 10wt% HF. Detailed Implementation

[0030] To further clarify and illustrate the technical solution of the present invention, the following non-limiting embodiments are provided. While considerable effort has been made to ensure the accuracy of the numerical values ​​in these embodiments, some errors and deviations must be considered. The composition itself is given based on oxides in mole percent and has been normalized to 100%. Performance testing of the glass material of the present invention is described below:

[0031] Crystal phase and crystallinity:

[0032] The crystalline phase of the glass-ceramic was confirmed by XRD testing. The testing method is as follows: the glass-ceramic product was crushed and ground into powder. The powdered sample was then tested using an X-ray diffractometer to obtain the XRD diffraction peak curve and XRD diffraction data. The X-ray diffractometer used in this application was a Rigaku Ultima IV from Japan, with a testing range of 2θ from 10° to 35° and a scanning speed of 10° / min. Finally, the XRD diffraction data was analyzed using Jade software to determine the crystalline phase in the glass sample. The XRD test results (RAW format) were imported into Jade software for fitting and calculation to determine the crystallinity of the sample.

[0033] Grain size:

[0034] The surface of the glass-ceramic was treated with a 10wt% HF aqueous solution to prepare the sample, and then the sample was scanned and observed under a scanning electron microscope to determine the size of the grains.

[0035] Surface Na2O and K2O content: The elemental content of the sample surface was tested using X-ray fluorescence spectrometry (XRF). All samples were soaked in clean water for more than 30 minutes before testing to remove the salt adhering to the surface after chemical strengthening.

[0036] Stress: Stress was measured using a SLP-2000 glass surface stress meter. Tests were conducted on chemically strengthened glass-ceramics for DOL-Zero (DOL-0), CT_CV, CS_50, etc.

[0037] Drop Ball Height: This invention uses a drop ball tester to test the impact resistance of microcrystalline glass. Specifically, the microcrystalline glass sample is placed on a mold, and a 150g steel ball is dropped from a specified height. The maximum drop height from which the sample can withstand the impact without breaking is measured. More specifically, the test is conducted starting from a height of 30cm, with the center point dropped, and each subsequent drop increasing by 10cm until the microcrystalline glass breaks. At least 5 glass samples are taken from each batch for testing.

[0038] 80 / 180 grit sandpaper drop test: The average drop height resisted by sandpaper tested in this invention is used to characterize the drop damage resistance of chemically strengthened microcrystalline glass. A drop tester is used to perform a surface drop test on glass samples using 80 / 180 grit silicon carbide sandpaper. The model machine impacts the glass samples from a certain drop height, starting at 50cm and increasing in increments of 10cm, with one drop at each height until the glass breaks. The breakage height is recorded. At least five samples are used per batch, and the average value is taken.

[0039] The technical solution and its beneficial effects of the present invention will be further described below with reference to embodiments and comparative examples. However, it should be understood that these embodiments are only for illustrating the present invention and are not intended to limit the scope of protection of the present invention. For those skilled in the art, various modifications and substitutions made without departing from the concept of the present invention should fall within the scope of protection of the present invention.

[0040] Example 1

[0041] Weather-resistant glass-ceramics are prepared using the following method:

[0042] Step 1: Melting, using SiO2 59.54 mol% and Al2O3 1.45 mol%. The raw materials were prepared in the following proportions: 3.32 mol% ZrO2, 2.00 mol% Li2O3, 1.53 mol% P2O5, 0.06 mol% Na2O, 0.10 mol% K2O, 0.8 mol% CaO, 0.05 mol% Sb2O3, 0.08 mol% SnO2, and 1.15 mol% RE2O3, wherein RE2O3 was La2O3 and Eu2O3. The mixture was homogeneous and melted at 1400-1600℃. After clarification and homogenization, the molten glass was poured into a stainless steel mold preheated to 300-450℃. The annealing temperature was 450-500℃, and the temperature was reduced to 180-200℃ at a rate of 0.11-0.15℃ / min. Finally, the glass was cooled to room temperature in the furnace to obtain the glass precursor.

[0043] Step 2: Crystallization. The glass precursor obtained in Step 1 undergoes a crystallization heat treatment using a two-stage heat treatment process. The nucleation temperature is 500-600℃, and the holding time is 2-10 hours. The crystallization temperature is 680-760℃, and the holding time is 1-4 hours. After cooling, it is shaped, sliced, CNC machined, and polished. Upon completion of this step, a microcrystalline glass product with a crystallinity of 86% and lithium disilicate as the crystalline phase is obtained, with an average grain size of less than or equal to 50 nm. At this point, the thickness of the microcrystalline glass product is 0.6 mm.

[0044] Step 3: Chemical strengthening. The microcrystalline glass obtained in Step 2 is subjected to ion exchange treatment, specifically: two ion exchanges: the first ion exchange uses a molten salt mixture of 40wt% sodium nitrate + 60wt% potassium nitrate + 0.1wt% lithium nitrate at 480°C for 6 hours. Here, "0.1wt% LiNO3" refers to the addition of 0.1wt% LiNO3 based on the total mass of KNO3 and NaNO3. Other similar expressions in this invention have similar meanings. The second ion exchange uses a molten salt mixture of 30wt% sodium nitrate + 70wt% potassium nitrate + 0.05wt% lithium nitrate at 460°C for 60 minutes. After two chemical strengthening processes, its DOL-0 is measured to be 113μm.

[0045] Step 4: Re-polishing. As can be seen from the results in Step 2, the main crystalline phase of the glass-ceramic is lithium disilicate. The selection of the removal thickness is the key issue to be considered in this step. In the prior art, the removal thickness is generally based on experience. However, in this application, if the removal thickness is too thin, the sodium and potassium on the surface cannot be effectively removed, and the high temperature and high humidity aging performance is weak. If the removal thickness is too large, the glass-ceramic will lose its mechanical properties. The measured DOL-0 of the microcrystalline glass was substituted into the single-sided removal thickness proposed in this application, which should be (0.04-0.51)×(1-Xc)×DOL-0, in μm. Specifically, in this embodiment, it is (0.04-0.51)×0.14×113=0.6-8.1μm, and the double-sided removal thickness is 1.2-16.2μm. The applicant verified the polishing removal of different thicknesses and tested their performance. The Na2O content and K2O content in the microcrystalline glass with a surface thickness of 0-30µm were tested. After placing it in an 85℃ / 85% RH environment for 240h, the haze, ROR, drop height of a 150g steel ball, average failure height of 80-grit sandpaper, average failure height of 180-grit sandpaper, CT_CV and CS_50 were tested before and after high temperature and humidity aging test, as detailed in Table 1.

[0046] Table 1

[0047] As shown in Table 1, in step 4 of Example 1, the thickness removed on one side during the back polishing process is within the range of (0.04-0.51)×(1-Xc)×DOL-0. After back polishing, the content of sodium oxide on the surface does not exceed 7wt%, and the content of potassium oxide on the surface does not exceed 0.8wt%. The resulting microcrystalline glass exhibits good resistance to high temperature and high humidity aging, and the drop height after aging decreases by no more than 20% compared to the initial value. However, the microcrystalline glass obtained by removing the thickness outside this range has weaker resistance to high temperature and high humidity aging, and the drop height after aging decreases by more than 20% compared to the initial value.

[0048] Example 2

[0049] The difference between steps 1-3 in this embodiment and those in Embodiment 1 is the composition of the raw materials. In this embodiment, the raw materials consist of 56.01 mol% SiO2 and 1.48 mol% Al2O3. The raw materials were prepared in the following proportions: mol% ZrO2 4.46 mol%, Li2O 33.46 mol%, P2O5 1.87 mol%, Na2O 0.5 mol%, K2O 0.04 mol%, BaO 1.22 mol%, Sb2O3 0.06 mol%, SnO2 0.01 mol%, and RE2O3 0.89 mol%, where RE2O3 was La2O3 and Y2O3. The resulting microcrystalline glass had a crystallinity of 90%, a crystalline phase of lithium disilicate, an average grain size of less than or equal to 50 nm, and a thickness of 0.6 mm. After two chemical strengthening processes, the same as in Example 1, its DOL-0 was measured to be 114 μm. In this embodiment, the single-sided removal thickness is (0.04-0.51)×0.1×114=0.5-5.8μm, and the double-sided removal thickness is 1.0-11.6μm. The applicant verified the removal of different thicknesses by single-sided polishing and tested its performance. The Na2O content and K2O content in the microcrystalline glass with a surface thickness of 0-30µm were tested, and the drop height of a 150g steel ball was measured after placing it in an environment of 85℃ / 85% RH for 240h. The test results are shown in Table 2.

[0050] Table 2

[0051] As shown in Table 2, in step 4 of Example 2, the thickness removed on one side during the back polishing process is within the range of (0.04-0.51)×(1-Xc)×DOL-0. After back polishing, the content of sodium oxide on the surface does not exceed 7wt%, and the content of potassium oxide on the surface does not exceed 0.8wt%. The resulting microcrystalline glass exhibits good resistance to high temperature and high humidity aging, and the drop height after aging decreases by no more than 20% compared to the initial value. However, the microcrystalline glass obtained by removing thicknesses outside this range has weaker resistance to high temperature and high humidity aging, and the drop height after aging decreases by more than 20% compared to the initial value.

[0052] Example 3

[0053] Steps 1-3 differ from those in Example 1 in the composition of the raw materials. In this example, the raw materials consist of 57.94 mol% SiO2 and 1.48 mol% Al2O3. The raw materials were prepared in the following proportions: ZrO2 4.81 mol%, Li2O 31.58 mol%, P2O5 1.7 mol%, Na2O 1 mol%, K2O 0.02 mol%, Sb2O3 0.02 mol%, SnO2 0.12 mol%, and RE2O3 1.33 mol%, where RE2O3 was Sm2O3 and Yb2O3. The resulting microcrystalline glass had a crystallinity of 81%, a crystalline phase of lithium disilicate, an average grain size of less than or equal to 50 nm, and a thickness of 0.6 mm. After two chemical strengthening processes, the same as in Example 1, its DOL-0 was measured to be 116 μm. In this embodiment, the single-sided removal thickness is (0.04-0.51)×0.19×116=0.9-11.2μm, and the double-sided removal thickness is 1.8-22.4μm. The applicant verified the removal thickness of different thicknesses by single-sided polishing and tested its performance. The Na2O content and K2O content in the microcrystalline glass with a surface thickness of 0-30µm were tested, and the drop height of a 150g steel ball was measured after placing it in an environment of 85℃ / 85% RH for 240h. The test results are shown in Table 3.

[0054] Table 3

[0055] As shown in Table 3, in step 4 of Example 3, the thickness removed on one side during the back polishing process is within the range of (0.04-0.51)×(1-Xc)×DOL-0. After back polishing, the content of sodium oxide on the surface does not exceed 7wt%, and the content of potassium oxide on the surface does not exceed 0.8wt%. The resulting microcrystalline glass exhibits good resistance to high temperature and high humidity aging, and the drop height after aging decreases by no more than 20% compared to the initial value. However, the microcrystalline glass obtained by removing the thickness outside this range has weaker resistance to high temperature and high humidity aging, and the drop height after aging decreases by more than 20% compared to the initial value.

[0056] Example 4

[0057] Steps 1-3 differ from those in Example 1 in the composition of the raw materials. In this example, the raw materials are prepared in the following proportions: SiO2 61.67 mol%, Al2O3 2.79 mol%, ZrO2 3.8 mol%, Li2O 27.60 mol%, P2O5 1.31 mol%, Na2O 1.34 mol%, CaO 1.05 mol%, BaO 0.03 mol%, Sb2O3 0.04 mol%, SnO2 0.1 mol%, and RE2O3 0.27 mol%, where RE2O3 is Sm2O3 and Eu2O3. The resulting microcrystalline glass has a crystallinity of 74%, a crystalline phase of lithium disilicate, an average grain size of less than or equal to 50 nm, and a thickness of 0.6 mm. After two chemical strengthening processes, the same as in Example 1, its DOL-0 was measured to be 111 μm. In this embodiment, the single-sided removal thickness is (0.04-0.51)×0.26×111=1.2-14.7μm, and the double-sided removal thickness is 2.4-29.4μm. The applicant verified the removal of different thicknesses by single-sided polishing and tested its performance. The Na2O content and K2O content in the microcrystalline glass with a surface thickness of 0-30µm were tested, and the drop height of a 150g steel ball was measured after placing it in an 85℃ / 85% RH environment for 240h. The test results are shown in Table 4.

[0058] Table 4

[0059] As shown in Table 4, in step 4 of Example 4, the thickness removed on one side during the back polishing process is within the range of (0.04-0.51)×(1-Xc)×DOL-0. After back polishing, the content of sodium oxide on the surface does not exceed 7wt%, and the content of potassium oxide on the surface does not exceed 0.8wt%. The resulting microcrystalline glass exhibits good resistance to high temperature and high humidity aging, and the drop height after aging decreases by no more than 20% compared to the initial value. However, the microcrystalline glass obtained by removing the thickness outside this range has weaker resistance to high temperature and high humidity aging, and the drop height after aging decreases by more than 20% compared to the initial value.

[0060] Example 5

[0061] Steps 1-3 differ from those in Example 1 in the composition of the raw materials. In this example, the raw materials are prepared in the following proportions: SiO2 66.4 mol%, Al2O3 1.7 mol%, ZrO2 4.33 mol%, Li2O 24.66 mol%, P2O5 1.45 mol%, K2O 0.15 mol%, CaO 0.8 mol%, BaO 0.22 mol%, Sb2O3 0.07 mol%, SnO2 0.02 mol%, and RE2O3 0.2 mol%, where RE2O3 is La2O3. The resulting microcrystalline glass has a crystallinity of 60%, a main crystalline phase of lithium disilicate, an average grain size of less than or equal to 50 nm, and a thickness of 0.6 mm. After two chemical strengthening processes, the same as in Example 1, its DOL-0 was measured to be 112 μm. In this embodiment, the single-sided removal thickness is (0.04-0.51)×0.4×112=1.8-22.8μm, and the double-sided removal thickness is 3.6-45.6μm. The applicant verified the removal of different thicknesses by single-sided polishing and tested its performance. The Na2O content, K2O content, and CS_50 in the microcrystalline glass with a surface thickness of 0-30µm were tested. The drop height of a 150g steel ball was measured after placing it in an environment of 85℃ / 85% RH for 240h. The test results are shown in Table 5.

[0062] Table 5

[0063] As shown in Table 5, in step 4 of Example 5, the thickness removed on one side during the back polishing process is within the range of (0.04-0.51)×(1-Xc)×DOL-0. After back polishing, the content of sodium oxide on the surface does not exceed 7wt%, and the content of potassium oxide on the surface does not exceed 0.8wt%. The resulting microcrystalline glass exhibits good resistance to high temperature and high humidity aging, and the drop height after aging decreases by no more than 20% compared to the initial value. However, the microcrystalline glass obtained by removing thicknesses outside this range has weaker resistance to high temperature and high humidity aging, and the drop height after aging decreases by more than 20% compared to the initial value.

[0064] As can be seen from Examples 1-5, the results are consistent with the theoretical analysis proposed in this invention. Experiments show that when the removal amount satisfies the aforementioned relationship, the retention rate of mechanical properties of the microcrystalline glass after high-temperature and high-humidity aging is significantly better than that of samples deviating from this range. Removal below the lower limit causes non-ideal layer residue, leading to aging starting from surface "ulcers" and subsequent rapid performance degradation; removal above the upper limit causes the effective stress layer to be thinned, resulting in glass weakening and rapid stress relaxation during aging, thus leading to a decrease in mechanical properties.

[0065] Examples 6-10 were used to verify the effect of raw material composition on the final product. Unlike Example 1, the raw material composition was different. The raw material composition, crystal phase, and crystallinity of Examples 6-10 are shown in Table 6.

[0066] Table 6

[0067] The microcrystalline glass prepared in Examples 6-12 was subjected to two chemical strengthening treatments and a repolishing treatment. Examples 6-12 were mainly used to verify the influence of raw material composition on the final product. Only one value was selected for the thickness removal d. The strengthening conditions, thickness removal and test results are shown in Table 7.

[0068] Table 7

[0069] Comparative Examples 1-6

[0070] Comparative Examples 1-6 were used to verify the influence of raw material composition on the final product. Unlike Example 1, the raw material composition was different. The raw material composition, crystal phase, crystallinity and test results of Comparative Examples 1-6 are shown in Table 8.

[0071] Table 8

[0072] The basic glass chemical composition of Examples 1-10 all fall within the scope defined by the present invention, and the resulting microcrystalline glass has lithium disilicate as the main crystalline phase and a crystallinity between 60-90%. Figure 1 The images show the XRD patterns of the glass-ceramics prepared in Examples 1 and 5. Figure 1 It can be seen that the main crystalline phase of the prepared glass-ceramic is lithium disilicate, containing a small or very small amount of petalite. The SEM image of the glass-ceramic prepared in Example 1 after etching with 10% HF acid is shown below. Figure 2 As shown, by Figure 2As can be seen, the microcrystalline glass prepared in Example 1 has smaller grains, not exceeding 50 nm. After removing an appropriate surface thickness, the surface Na2O content of each example sample is approximately 6-6.9 wt%, and the surface K2O content is approximately 0.03-0.8 wt%, which is better than the cases of alkali metal enrichment in Comparative Examples 1 and 2. This indicates that within the range of Na2O, K2O, and rare earth oxide content defined by this invention, the degree of alkali metal enrichment in the surface layer can be effectively controlled, thereby improving the chemical stability of the microcrystalline glass in high-temperature and high-humidity environments from the source. Excessive rare earth oxide content in Comparative Example 3 also leads to excessive loss of mechanical properties after high-temperature and high-humidity aging tests of the final product. Similarly, excessively low or high zirconium oxide content in Comparative Examples 4 and 5 also results in weakened mechanical properties. This may be because excessively low zirconium oxide leads to a loose glass network, coarse grains, and easy entry of moisture; while excessively high zirconium oxide results in residual refractory particles, hindered ion exchange, and moisture erosion along defects. Only within a suitable range can both structural density and strengthening effects be balanced to obtain optimal weather resistance. When the amount of calcium oxide in Comparative Example 6 exceeded the maximum range, the mechanical properties of the final product also suffered excessive loss after high temperature and high humidity aging test. The possible reason is that when there is an excess of calcium oxide, it will be squeezed into the hydrophilic and loosely structured grain boundary glass. Under high temperature and high humidity conditions, water vapor can enter more easily, resulting in poor weather resistance.

[0073] The basic glass composition system proposed in this invention, combined with the optimized secondary chemical strengthening process, can achieve high mechanical strength while also ensuring low haze, excellent high-temperature and high-humidity reliability, and good fracture morphology. It is suitable for use as cover glass for electronic products, automotive displays, wearable devices, and other applications with high reliability requirements.

Claims

1. A method for preparing weather-resistant microcrystalline glass, characterized in that, Includes the following steps: Step 1: Melting. Prepare raw materials in a certain proportion, mix them evenly, melt the evenly mixed raw materials into a mold, and then anneal them to obtain the glass precursor. Step 2: Crystallization. The glass precursor obtained in Step 1 is subjected to crystallization heat treatment. After cooling, it is shaped, sliced, CNC machined, and polished. Step 3: Chemical strengthening. The microcrystalline glass obtained in Step 2 is subjected to ion exchange treatment and then polished to obtain the finished product. The polishing requirements in this step are as follows: the microcrystalline glass product is polished on both sides, and the thickness d removed by single-sided polishing is d=k×(1-Xc)×DOL-0, with the unit being µm, where k=0.04-0.51, Xc is the crystallinity of the microcrystalline glass, and DOL-0 is the ion exchange depth; the thickness removed by double-sided polishing is 2d.

2. The method for preparing weather-resistant microcrystalline glass according to claim 1, characterized in that, The raw materials in step 1 consist of: SiO2 55-75 mol%, Al2O3 0.5-4 mol%, ZrO2 2-10 mol%, Li2O 20-35 mol%, P2O5 0.5-3 mol%, Na2O 0-3 mol%, K2O 0-0.5 mol%, CaO 0-3 mol%, BaO 0-3 mol%, Sb2O3 0-0.6 mol%, SnO2 0-0.6 mol%, and RE2O3 0-3 mol%, wherein RE2O3 is one or more of La2O3, Y2O3, Sm2O3, Eu2O3, and Yb2O3.

3. The method for preparing weather-resistant microcrystalline glass according to claim 1, characterized in that, In step 2, crystallization is performed using a two-stage heat treatment process. The nucleation treatment temperature is 500-600℃, and the holding time is 2-10h. The crystallization treatment temperature is 680-760℃, and the holding time is 1-4h.

4. The method for preparing weather-resistant microcrystalline glass according to claim 1, characterized in that, In step 3, the chemical strengthening is carried out in two stages: the first chemical strengthening is performed by treating a molten salt mixture of 20-80 wt% sodium nitrate, 20-80 wt% potassium nitrate, and 0.04-0.3 wt% lithium nitrate at 400-530°C for 2-8 hours; the second chemical strengthening is performed by treating a molten salt mixture of 0-30 wt% sodium nitrate, 70-100 wt% potassium nitrate, and 0-0.05 wt% lithium nitrate at 350-500°C for 20-120 minutes.

5. A weather-resistant microcrystalline glass, characterized in that, It is prepared by the method described in any one of claims 1-4.

6. The weather-resistant microcrystalline glass according to claim 5, characterized in that, The main crystal phase of the weather-resistant glass-ceramics is lithium disilicate, or lithium disilicate and spodumene, and the crystallinity is 60-90%; the content of Na2O in the 0-30 μm thickness on the surface of the weather-resistant glass-ceramics is ≤ 7 wt%, and 0 < the content of K2O ≤ 0.8 wt%; the composition of the weather-resistant glass-ceramics is: SiO2 55-75 mol%, Al2O3 0.5-4 mol%, ZrO2 2-10 mol%, Li2O 20-35 mol%, P2O5 0.5-3 mol%, Na2O 0-7 mol%, K2O 0.01-0.5 mol%, CaO 0-3 mol%, BaO 0-3 mol%, Sb2O3 0-0.6 mol%, SnO2 0-0.6 mol% and RE2O3 0-3 mol%, where RE2O3 is one or more of La2O3, Y2O3, Sm2O3, Eu2O3 and Yb2O3.

7. The weather-resistant microcrystalline glass according to claim 5 or 6, characterized in that, When the weather-resistant glass-ceramics are placed for 240 hours under the conditions of a temperature of 85 °C and a humidity of 85% RH, the average failure height of the 150 g steel ball dropping is reduced by no more than 20% compared with the initial value before aging.

8. A glass device, characterized in that, The glass device comprises the weather-resistant glass-ceramics as described in Claim 5 or 6.

9. A cover glass, characterized in that, The cover glass comprises the weather-resistant glass-ceramics as described in Claim 5 or 6.

10. An electronic device, characterized in that, The electronic device comprises the weather-resistant glass-ceramics as described in Claim 5 or 6.

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