A microcrystalline glass ingot and its preparation method, microcrystalline glass, cover glass, and electronic devices.

Abstract

This invention discloses a microcrystalline glass ingot and its preparation method, microcrystalline glass, cover glass and electronic devices. With the goal of large-size continuous casting, a combination of "low crystallization tendency formula" and "asymmetric gradient temperature control mold" is used to produce a microcrystalline glass ingot with a thickness of more than 80mm and uniform internal transparency. This achieves the goal of continuous vertical slicing without splicing when applied to the mobile phone field, which greatly improves the material utilization rate.

Description

Technical Field

[0001] This invention belongs to the field of inorganic materials, specifically relating to a microcrystalline glass ingot and its preparation method, microcrystalline glass, cover glass, and electronic equipment. Background Technology

[0002] With the increasing demand for drop-resistant performance in the consumer electronics market, lithium aluminum silicon (LISi) microcrystalline glass has emerged. Microcrystalline glass is a new type of glass containing a large number of crystals. These crystal particles can deflect cracks, hindering their extension and propagation, thus exhibiting excellent drop resistance. Currently, the manufacturing process of LISi microcrystalline glass commonly employs a continuous casting and cutting method. This involves using a high-temperature casting furnace, similar to those used in optical glass, followed by clarification and homogenization. The material is then discharged from a platinum tube and molded into continuous strips of a certain width and thickness. These strips are then blasted into glass ingots, crystallized, and cut. The typical thickness of LISi microcrystalline glass ingots is currently 20-50 mm. Exceeding this thickness range causes crystallization and whitening in the core of the ingot, affecting the optical and mechanical properties of the product. Since the width of typical mobile phone screen cover glass is 70-80mm, under current production capacity, vertical slicing of 20-50mm thick microcrystalline glass ingots requires shaping and gluing the ingots, making continuous vertical slicing impossible. This means significant cutting losses occur, such as tangent loss and edge loss due to glue splicing. These losses drastically reduce the yield of microcrystalline glass, thus impacting costs. Therefore, there is an urgent need to develop a microcrystalline glass ingot production technology that allows for continuous vertical cutting without splicing, in order to reduce the cutting cost of microcrystalline glass ingots and consequently lower the overall production cost of microcrystalline glass. Summary of the Invention

[0003] To overcome the shortcomings of existing technologies, this invention provides a method for producing microcrystalline glass ingots with a thickness exceeding 80mm, allowing for continuous vertical cutting and seamless application as mobile phone screen cover glass. This method improves production efficiency and reduces production costs while ensuring optical and mechanical properties. The specific technical solution of this invention is as follows: A method for preparing a microcrystalline glass ingot includes the following steps: Step 1: Prepare the raw materials according to the following composition: SiO2 60-75wt%, Al2O3 0.5-6wt%, ZrO2 5-15wt%, Li2O 11-16wt%, P2O5 0.5-5wt%, Na2O 0-2wt%, K2O 0-1wt%, CaO 0-3wt%, Sb2O3 0-0.6wt%, SnO2 0-0.6wt%, and mix them evenly. Step 2: Melting and Casting. The raw material obtained in Step 1 is transferred to a furnace and gradually heated to 1200℃~1600℃ to obtain molten glass. The molten glass is clarified and homogenized through a platinum channel before being discharged into a mold. The temperature at the platinum outlet is controlled at 1100-1150℃, the surface temperature of the bottom mold is 550-650℃, the surface temperature of the side mold is 470-520℃, and the surface temperature of the back grate is 420-490℃, resulting in a glass ingot. In some embodiments, the temperature at the platinum outlet is... The temperature is controlled at 1100℃, 1110℃, 1120℃, 1130℃, 1140℃, or 1150℃, or within any two of the above specific values ​​as endpoints; the bottom mold surface temperature is 550℃, 560℃, 570℃, 580℃, 590℃, 600℃, 610℃, 620℃, 630℃, 640℃, or 650℃, or within any two of the above specific values ​​as endpoints. A high bottom mold temperature ensures that the molten glass can spread and fuse at the bottom of the mold. If the temperature is too high, the core will crystallize and turn white when the molten glass solidifies. If the temperature is too low, the molten glass will generate large shrinkage stress when it solidifies. The side mold surface temperature is 470℃, 480℃, 490℃, 500℃, 510℃, or 520℃, or any value within the range defined by any two of the above specific values. The side mold mainly affects the forming radius (R-angle). If the side mold temperature is too high, the R-angle is small, but the glass melt has difficulty dissipating heat, and the side edges will crystallize and turn white. If the temperature is too low, the R-angle is large, and the utilization rate of glass edge material is low. The back baffle surface temperature is 420℃, 430℃, 440℃, 450℃, 460℃, 470℃, 480℃, or 490℃, or any value within the range defined by any two of the above specific values. If the back baffle temperature is low, the glass melt solidifies quickly, shrinks greatly, and the glass melt forming R-angle and bottom shrinkage are large. If the back baffle temperature is high, the glass melt is easy to stick to the back baffle, leading to high-temperature crystallization and whitening of the glass melt.

[0004] Step 3: After annealing the glass ingots obtained in Step 2 in a mesh belt furnace, cut them into a certain size. Step 4: Perform nucleation and crystallization treatment on the glass ingot obtained in Step 3 to obtain the final microcrystalline glass ingot.

[0005] Furthermore, in step 2, the liquidus temperature range of the molten glass is 980-1060°C. In some embodiments, the liquidus temperature of the molten glass in step 2 is 980°C, 990°C, 1000°C, 1010°C, 1020°C, 1030°C, 1040°C, 1050°C, or 1060°C, or a value within a range defined by any two of the above specific values ​​as endpoints.

[0006] Furthermore, the viscosity of the molten glass in step 2 meets the following requirements: 3000-8000 dPa·S at 1000℃; 1000-2000 dPa·S at 1100℃; 300-1000 dPa·S at 1200℃; 100-300 dPa·S at 1300℃; and 10-100 dPa·S at 1400℃. In some embodiments, the viscosity of the molten glass in step 2 satisfies the following conditions: at 1000°C, the viscosity is 3000 dPa·s, 3500 dPa·s, 4000 dPa·s, 4500 dPa·s, 5000 dPa·s, 5500 dPa·s, 6000 dPa·s, 6500 dPa·s, 7000 dPa·s, 7500 dPa·s, or 8000 dPa·s, or falls within any two of the above specific values ​​as endpoints. Values ​​within the range defined by the given values; at 1100℃, the viscosity is 1000 dPa·s, 1100 dPa·s, 1200 dPa·s, 1300 dPa·s, 1400 dPa·s, 1500 dPa·s, 1600 dPa·s, 1700 dPa·s, 1800 dPa·s, 1900 dPa·s, or 2000 Pa·s, or values ​​falling within the range defined by any two of the above specific values ​​as endpoints. At 1200℃, the viscosity is 300 dPa·s, 400 dPa·s, 500 dPa·s, 600 dPa·s, 700 dPa·s, 800 dPa·s, 900 dPa·s, or 1000 dPa·s, or a value within the range defined by any two of the above specific values ​​as endpoints; at 1300℃, the viscosity is 100 dPa·s, 150 dPa·s, 200 dPa·s, or 250 dPa·s. S or 300 dPa·S or a value within the range of any two of the above specific values ​​as endpoints; at 1400℃, the viscosity is 10 dPa·S or 20 dPa·S or 30 dPa·S or 40 dPa·S or 50 dPa·S or 60 dPa·S or 70 dPa·S or 80 dPa·S or 90 dPa·S or 100 dPa·S or a value within the range of any two of the above specific values ​​as endpoints.

[0007] The glass ingot obtained in step 2 has a radius of R-angle ≤ 10 mm; the thickness of the glass ingot is not less than 50 mm, and further, the thickness of the glass ingot is 80-120 mm, preferably 80-90 mm; the transmittance in the thickness direction of the glass ingot is 70-80%, and the haze is ≤ 5; the crystal phase is silicon dioxide.

[0008] Preferably, the crystallization process in step 4 is a three-stage nucleation crystallization process, with the first crystallization temperature at 500-650℃ and the holding time at 0.5-10h; the second crystallization temperature at 600-700℃ and the holding time at 0.5-5h; and the third crystallization temperature at 700-750℃ and the holding time at 0.5-5h.

[0009] A microcrystalline glass ingot is prepared by the aforementioned method.

[0010] A type of microcrystalline glass is obtained by slicing the aforementioned microcrystalline glass ingot.

[0011] Furthermore, the crystal phase of the microcrystalline glass is lithium disilicate and / or lithium feldspar and / or lithium monosilicate and / or silicon dioxide, with a crystallinity of 60-90%.

[0012] Furthermore, the microcrystalline glass, with a thickness of 0.4-0.8 mm, has a transmittance of ≥91% in the visible light wavelength range.

[0013] A cover glass comprising the aforementioned microcrystalline glass.

[0014] An electronic device comprising the aforementioned microcrystalline glass.

[0015] In the preparation of large-size microcrystalline glass ingots, especially those exceeding 50mm in thickness, the glass liquidus temperature and viscosity are two core process parameters that directly affect the success rate of molding, internal quality, and the uniformity of subsequent crystallization. Liquidus temperature: This is the lowest temperature at which the melt will not crystallize. During large ingot casting, a large temperature gradient is generated inside the ingot due to the cooling effect of the mold. If the melt temperature is not properly controlled, devitrification will occur if local areas (especially the surface and corners) remain near the liquidus temperature for an extended period, leading to crystallization or surface glazing in the ingot. Viscosity: Large-size molding requires the melt to have good molding ability. If the viscosity is too high, the melt has poor fluidity and cannot fill the corners of the mold, resulting in missing corners in the ingot; at the same time, air bubbles are difficult to completely expel before casting. If the temperature is significantly increased to reduce viscosity, interface crystallization is easily caused by the liquidus temperature problem. Finding a balance between "high temperature easily crystallizes" and "low temperature is difficult to mold" is crucial for large-size preparation. In this invention, the composition is adjusted through basic raw material formulation design to achieve a low liquidus line and a suitable viscosity-temperature curve (i.e., low viscosity at high temperature facilitates degassing, moderate viscosity increase at low temperature facilitates annealing, and does not intersect with the liquidus line).

[0016] SiO2 is the main constituent of the glass network, and its content directly affects the glass's melting characteristics, viscosity, and mechanical strength. A suitable SiO2 content maintains a stable glass network structure, enhances resistance to crack propagation, and thus improves drop resistance. However, if the SiO2 content is too high, the melting temperature rises, affecting glass forming; if it is too low, the network structure becomes loose, reducing the glass's hardness and impact resistance. Therefore, in this invention, the SiO2 content is 60-75 wt%, preferably 62-75 wt%, and more preferably 62-73 wt%.

[0017] Al2O3, as a network intermediate, can partially replace SiO2 in the network structure, filling network voids. It can also combine with Li2O and SiO2 to form a lithium feldspar crystal phase, improving the mechanical strength and scratch resistance of the glass. Too low an Al2O3 content hinders crystal precipitation and makes it difficult to increase the glass phase modulus, thus reducing its impact resistance. Too high an Al2O3 content leads to severe crystallization, affecting the optical and mechanical properties of the glass material. Therefore, in this invention, the Al2O3 content is 0.5-6 wt%, preferably 0.5-5.5 wt%, and more preferably 1-5.5 wt%.

[0018] A suitable amount of P2O5 can lower the liquidus temperature, preventing premature precipitation of mullite or quartz, and preventing crystallization of high-lithium systems in the critical temperature range, thus disrupting the continuity of the viscosity curve. In this invention, the P2O5 content is 0.5-5.5 wt%, preferably 2-5 wt%, and more preferably 2-4 wt%.

[0019] CaO, as a network modifier, can break the Si-O-Si network, increase the density of non-bridging oxygen, and lower the melting temperature. It can also modulate ion exchange channels; a small amount of Ca... 2+ It can partially occupy the migration channels of alkali metal ions, affecting the exchange rate and optimizing the stress structure. If the CaO content is too high, Ca... 2+ High CaO content can clog diffusion channels and impose stricter requirements on ion exchange conditions. Furthermore, high CaO content can easily lead to glass crystallization, affecting optical performance. Therefore, the CaO content in this invention is 0-4 wt%, preferably 0-3 wt%, and more preferably 0-2 wt%.

[0020] ZrO2 is a highly efficient nucleating agent that optimizes crystal size and distribution, thereby improving the mechanical properties of materials. Simultaneously, ZrO2 strengthens the glass network structure, enabling the material to withstand greater internal tensile stress and prevent fracture, thus increasing the upper limit of the CT value. 4+ZrO2 tends to accumulate in grain boundary regions, increasing the elastic modulus of the glass phase while suppressing abnormal grain growth. Too low a ZrO2 content affects crystallization uniformity, leading to large grain size differences and localized stress concentration. Too high a ZrO2 content causes a sharp increase in glass melt viscosity, making it difficult to remove bubbles and affecting product yield. It also easily leads to excessive crystallization and low transmittance. Therefore, the ZrO2 content in this invention is 5-15 wt%, preferably 5.5-12 wt%, and more preferably 6-10 wt%.

[0021] Li₂O, as a strong flux, significantly lowers the melting point and liquidus of glass. Higher Li₂O content increases glass network breakage (increases non-bridging oxygen), further lowering the liquidus. However, excessive Li₂O also promotes the precipitation of β-quartz / β-spodumene solid solutions. Therefore, in this invention, the Li₂O content is 10-16 wt%, preferably 11-15.5 wt%, and more preferably 12-15 wt%.

[0022] Na₂O, as a network modifier, can effectively lower the melting temperature. It is also a core component for chemical fortification, its main function being to provide exchangeable Na₂O. + In molten salt with K + Displacement occurs, regulating the high central tensile stress. Excessive Na₂O content increases the coefficient of thermal expansion of the glass, thus reducing its thermal stability. Therefore, the upper limit of Na₂O content in this invention is set at 2 wt%, preferably 0-1.5 wt%, and more preferably 0.1-1.5 wt%.

[0023] K₂O, as a flux, can lower the melting temperature and crystallization tendency of glass. However, as a network modifier, its network-breaking effect can reduce the mechanical strength, thermal stability, and weather resistance of glass; therefore, its content should not be too high. Thus, the K₂O content in this invention is 0-1 wt%, preferably 0.1-1 wt%, and more preferably 0.1-0.7 wt%. The total amount of Na₂O, K₂O, and CaO should not be too high, otherwise it will violate the upper limit of low-temperature viscosity at 1000℃.

[0024] SnO2 and Sb2O3 are used as clarifying agents and have a significant impact on the melting quality of glass. SnO2 and Sb2O3 can reduce or eliminate small bubbles in the melt, improving the clarity and uniformity of the glass; their combined effect is even better. However, excessive addition of SnO2 and Sb2O3 increases the risk of glass devitrification, affecting product quality. Therefore, the upper limit of SnO2 content in this invention is set at 0.6 wt%, preferably 0-0.5 wt%, and more preferably 0-0.2 wt%. The upper limit of Sb2O3 content in this invention is set at 0.6 wt%, preferably 0-0.5 wt%, and more preferably 0-0.4 wt%.

[0025] This invention overcomes thickness limitations by combining temperature field, product formulation, and molding process.

[0026] 1. Synergistic effect of formulation design The performance of glass-ceramics depends on the type and quantity of precipitated crystals. The SiO2-Al2O3-Li2O-ZrO2-P2O5 system is the key foundation: ZrO2 (zirconia) and P2O5 (phosphorus pentoxide) are composite nucleating agents. During heat treatment, they promote the precipitation of main crystalline phases such as Li2Si2O5 (lithium disilicate), giving the glass high strength and wear resistance. Controlling the ratio of SiO2 to Al2O3 ensures an intact network structure without excessive free oxygen, preventing SiO2 crystal precipitation at high temperatures; a low Al2O3 / P2O5 mass ratio lowers the liquidus temperature of the glass melt; and an Al2O3 content designed to be below 6 wt% helps stabilize the glass structure, reduces the viscosity of the glass melt, and allows the glass melt to flow fully and fill the mold, preventing spontaneous crystallization during the forming and cooling process. This is a prerequisite for producing large-size glass—ensuring that the interior remains transparent and does not turn white during cooling.

[0027] 2. Differentiated temperature-controlled molding For thick glass, the cooling rates inside and outside differ, with slower internal heat dissipation leading to crystallization and whitening. This invention addresses this issue through precise mold temperature control. Specifically, high-temperature discharge ensures good fluidity of the molten glass, allowing it to smoothly fill the thick mold; a high-temperature bottom mold allows for slow cooling of the glass ingot's bottom. If the bottom is too cold, the glass will solidify rapidly, causing shrinkage lines and internal stress, preventing heat dissipation. Maintaining a high-temperature bottom mold ensures even heat transfer from the bottom, resulting in more consistent cooling of the entire glass. A medium-temperature side mold, with the sidewall temperature slightly lower than the bottom mold, aids in the initial shaping of the glass ingot's sides, preventing collapse. The low-temperature backstage primarily aims to rapidly cool the molten glass, minimizing its residence time in the high-temperature zone and reducing the likelihood of high-temperature crystallization. By designing a gradient temperature field, the rate of heat loss from the inside to the outside of the glass ingot is controlled, minimizing the temperature gradient across the entire large cross-section of the glass during cooling. This prevents spontaneous internal crystallization (whitening) caused by localized overcooling or uneven cooling.

[0028] 3. Annealing and crystallization separation First, the thermal stress from the forming process is eliminated by annealing in a mesh belt furnace, followed by nucleation and crystallization heat treatment. This two-step method of "forming first and then crystallizing" allows for more precise control over the type and size of crystals, ensuring a uniform microstructure inside the thick glass.

[0029] This invention aims at large-size continuous casting. By combining a "low crystallization tendency formula" with an "asymmetric gradient temperature control mold", it produces microcrystalline glass ingots with a thickness of over 80mm and uniform internal transparency. This enables the application of these ingots in the mobile phone field to achieve the goal of continuous vertical slicing without splicing, thus significantly improving material utilization.

[0030] The beneficial technical effects of this invention are as follows: 1. Improve production efficiency and simplify processes: Since thick glass ingots that meet the width of mobile phone cover plates can be cast directly, there is no need for cutting, shaping and gluing blocks. This realizes continuous vertical slicing from glass ingots to cover plates, simplifying the process.

[0031] 2. Reduce production costs and waste: By eliminating the splicing process and the corresponding edge piece loss and tangent loss, the glass yield is greatly improved, thereby directly reducing raw material and processing costs. The production cost of microcrystalline glass produced by the method of this invention is reduced by at least 20%, and the production efficiency is increased by more than 15%.

[0032] 3. Ensuring performance and overcoming thickness bottlenecks: The technical problem of easy crystallization and whitening in the core of microcrystalline glass ingots (thickness exceeding 50mm) has been solved. While ensuring optical transmittance and mechanical strength, the thickness limitations of traditional processes have been successfully overcome. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the molding process section of the present invention; Figure 2 This is a schematic diagram of the glass ingot and its parameters in this invention; Figure 3 This is a diagram showing the state of the glass ingot before crystallization in Example 1 of the present invention; Figure 4 The XRD pattern of the glass ingot after cutting and polishing along the thickness direction at the crystallization front in Example 1 of this invention; Figure 5 This is a diagram showing the state of the glass ingot after crystallization in Embodiment 1 of the present invention; Figure 6 The image shown is the XRD pattern of the microcrystalline glass prepared in Example 1 of this invention. Figure 7 This is a graph showing the liquidus temperature of the glass melt in Example 6 of the present invention; Figure 8 The glass viscosity-temperature curves of Examples 1-6 of this invention; Figure 9 The image shown is the XRD pattern of the glass-ceramic prepared in Example 17 of this invention. Figure 10 This is a diagram of the uncrystallized state of glass ingot 10 (Comparative Example 10); Figure 11 This is a diagram showing the state of glass ingot 18 after crystallization (Comparative Example 18). Figure 12 The image shows the XRD pattern of the glass-ceramic prepared in Comparative Example 18.

[0034] 1-Platinum outlet; 2-Bottom mold; 3-Side mold; 4-Rear baffle; 5-Cooling pipe. Detailed Implementation

[0035] The casting process in this invention is described as follows: Figure 1 As shown, the high-temperature molten glass, after being clarified and stirred through a platinum channel, is discharged through platinum outlet 1. The molten glass passes through a steel bottom mold 2, side mold 3, and back baffle 4, and is shaped into a glass ingot with a specific thickness and width under the cooling action of cooling pipe 5. Cooling liquid, water, or gas can be introduced into cooling pipe 5. A schematic diagram of the glass ingot and its parameters is shown below. Figure 2 As shown, because it is a continuous discharge, the length direction is continuous and uninterrupted. It is then cut into glass ingots of specific length requirements through post-processing. In this key forming process, the material formula itself, the discharge temperature of the discharge port, and the temperature of the bottom mold / side mold / back section all affect the forming thickness and R-angle radius of the glass ingot, which in turn affect the transmittance, haze, and crystallinity of the formed glass ingot.

[0036] Liquidus temperature test method: The test is conducted in accordance with the national standard GB / T 44753-2024 Test method for liquidus temperature of ultrathin glass, and the starting temperature of the non-crystallized region is selected as the liquidus temperature of the glass.

[0037] Viscosity test method and curve: The viscosity was tested according to Part 13 of GB / T 7962.13—2010 Test Methods for Colorless Optical Glass: High Temperature Viscosity. A high-temperature resistant rotor (such as a platinum cylinder or cross-shaped rotor) was immersed in the molten glass and rotated at a constant speed at a set temperature. The viscosity was calculated by measuring the torque.

[0038] Transmittance and haze testing methods: Uncrystallized or crystallized glass ingots were cut and polished into sheets with a thickness of 148.2mm×68mm×0.6mm. The haze and transmittance of the glass sheets were tested using a HAM-300 remote haze meter.

[0039] Five-point crystallinity difference and its testing method: Uncrystallized or crystallized glass ingots were cut and polished into sheets with a thickness of 148.2mm×68mm×0.6mm. The XRD of the glass sheet was tested at five points (the center of the glass sheet and the four corners 20×20mm from the edge). The crystallinity of the glass sheet was calculated by Jade6.5, and the five-point range was taken as the crystallinity difference data.

[0040] Example 1

[0041] Microcrystalline glass ingots and microcrystalline glass were prepared according to the following steps. Step 1: Raw material preparation: SiO2: 69.08wt%, Al2O3: 4.73wt%, CaO: 0.27wt%, Na2O: 0.70wt%, K2O: 0.11wt%, ZrO2: 7.2wt%, Li2O: 13.2wt%, P2O5: 4.30wt%, SnO2: 0.04wt%, Sb2O3: 0.37wt%, mix evenly; Step 2: Transfer the raw material obtained in Step 1 into a high-temperature kiln and gradually heat it to 1200℃~1600℃. After clarification and homogenization through the platinum channel, the material is discharged into the mold through the platinum outlet. The molding is carried out according to the required temperature conditions of 1145℃ outlet temperature, 636℃ bottom mold temperature, 487℃ side mold temperature, and 465℃ back grate temperature to obtain glass ingots. Step 3: After annealing the glass ingots in a mesh belt furnace, cut them into glass ingots measuring 181.4mm (width) × 20mm (length) × 93.94mm (thickness). See the photo of the glass ingots below. Figure 3 As shown, Figure 3 As can be seen, the core of the glass ingot is not white. After cutting and polishing along the thickness direction, XRD testing was performed, and the test results are as follows. Figure 4 As shown, the glass ingot did not show obvious crystallization at this time; Step 4: The glass ingot is crystallized using a three-stage crystallization process. The crystallization process employs a three-stage nucleation crystallization method: the first crystallization temperature is 550℃, and the holding time is 4 hours; the second crystallization temperature is 650℃, and the holding time is 1 hour; the third crystallization temperature is 740℃, and the holding time is 1 hour. The crystallized glass ingot is as follows: Figure 5 As shown, the transmittance and haze of the crystallized microcrystalline glass ingot were tested. It was sliced ​​and polished into polished sheets measuring 148.2 mm (length) × 68 mm (width) × 0.6 mm (thickness) to test transmittance / haze / XRD properties. The XRD test results are shown below. Figure 6 As shown, by Figure 6 It can be seen that the crystal phases of the final microcrystalline glass are lithium disilicate, lithium feldspar and lithium monosilicate. Other test results are shown in Table 3-1.

[0042] Example 2-13 The differences from Example 1 are the composition of the raw materials and the outlet temperature, bottom mold / side mold / back grate temperature in the molding process. Specific raw material composition and process parameters are shown in Tables 1-1, 1-2, and 1-3. The liquidus test results of the glass in step 2 of Example 6 are as follows: Figure 7 As shown. The viscosity-temperature curves of the molten glass in step 2 of Examples 1-6 are as follows. Figure 8As shown. In step 2 of Examples 1-6, the molten glass has a low viscosity at high temperature, mainly to ensure uniform spreading of the glass in the mold, resulting in a smaller radius (R-angle) and a higher thickness. If the viscosity is high at high temperatures, the molten glass is prone to crystallization.

[0043] Comparative Examples 1-9 The difference from Example 1 is the composition of the raw materials and the outlet temperature, bottom mold / side mold / back baffle temperature in the molding process. The specific raw material composition and process parameters are shown in Tables 1-3 and 1-4.

[0044] The data or performance indicators in Tables 1-1 to 1-4 are all data for glass ingots or glass sheets that have not undergone crystallization treatment.

[0045] Table 1-1

[0046] Table 1-2

[0047] Table 1-3

[0048] Table 1-4

[0049] As can be seen from Tables 1-1 to 1-4, when the glass raw material composition is within the range of raw materials designed in this invention, the liquidus and viscosity of the glass melt at different temperatures can meet the requirements after melting. However, the glass melt made from raw materials not within the range of raw materials designed in this invention either fails to meet the requirements for liquidus or viscosity at different temperatures. Under the condition of meeting the molding process requirements, the transmittance of the glass ingots obtained in Comparative Examples 1-9 in the visible light range is 50-56%, and the haze is 6.4-15.8, which is significantly worse than the transmittance and haze of the glass ingots in Examples 1-13.

[0050] Furthermore, the effects of outlet temperature, bottom mold temperature, side mold temperature, and backstop temperature on the molding process were investigated. Examples 14-15 and Comparative Examples 10-17, using the same raw material composition and melting conditions as Example 1, studied the effects of different outlet temperatures, bottom mold temperatures, side mold temperatures, and backstop temperatures on the molding process. The molding process parameters and performance parameters of the glass ingots obtained in Examples 14-15 and Comparative Examples 10-17 are shown in Tables 2-1 and 2-2.

[0051] Table 2-1

[0052] Table 2-2

[0053] As shown in Tables 2-1 and 2-2, under the same raw material composition and melting conditions, changes in the outlet temperature, bottom mold temperature, side mold temperature, and backstop temperature all affect the optical properties of the produced glass ingot. When any one of the outlet temperature, bottom mold temperature, side mold temperature, or backstop temperature fails to meet the requirements, at least one of the following indicators of the produced glass ingot is found to be non-compliant: radius of curvature (≤10mm), transmittance in the thickness direction (70-80%), haze in the thickness direction (≤5%), crystallinity of the polished sheet (≤5%), and crystallinity difference at five points (≤5%). A photograph of the glass ingot (uncrystallized) obtained in Comparative Example 10 is shown below. Figure 10 As shown, by Figure 10 It is evident that the center of the glass ingot, which has not yet undergone crystallization treatment, is already noticeably white. If crystallization treatment is carried out, the transmittance will be even lower, making it unusable.

[0054] Examples 16-23 and Comparative Examples 18-22 were prepared with the same raw material composition and melting and molding process as Example 1 to study the effect of different crystallization processes on the final microcrystalline glass. Examples 16-23 and Comparative Examples 18-22 all adopted a three-stage crystallization process. The specific parameters of the crystallization process and the properties of the crystallized glass ingots and finished microcrystalline glass are shown in Tables 3-1 and 3-2.

[0055] Table 3-1

[0056] Table 3-2: Glass Ingot Crystallization Process

[0057] As shown in Tables 3-1 and 3-2, when the raw material composition, melting conditions and forming conditions are the same, changing the crystallization process conditions will affect the optical properties of the final microcrystalline glass ingot and microcrystalline glass sheet. When the three-stage crystallization process is used, if a certain crystallization temperature is not met, it is found that at least one of the following indicators does not meet the requirements: the transmittance of the glass ingot itself in the visible light range or the transmittance of the final microcrystalline glass in the visible light range (≥91%), the crystallinity of the polished sheet (≤5%), and the crystallinity difference of the five points (≤5%). Figure 11 and Figure 12 The images show photographs and XRD test results of the crystallized microcrystalline glass ingot prepared in Comparative Example 18.

Claims

1. A method of producing a glass-ceramic ingot, characterized in that, Includes the following steps: Step 1: Prepare the raw materials according to the following composition: SiO2 60-75wt%, Al2O3 0.5-6wt%, ZrO2 5-15wt%, Li2O 11-16wt%, P2O5 0.5-5wt%, Na2O 0-2wt%, K2O 0-1wt%, CaO 0-3wt%, Sb2O3 0-0.6wt%, SnO2 0-0.6wt%, and mix them evenly. Step 2: Melting and casting. The raw material obtained in Step 1 is transferred into the furnace and gradually heated to 1200℃~1600℃ to obtain molten glass. The molten glass is clarified and stirred through a platinum channel and then discharged into the mold. The temperature of the platinum outlet is controlled at 1100-1150℃, the surface temperature of the bottom mold is 550-650℃, the surface temperature of the side mold is 470-520℃, and the surface temperature of the back grate is 420-490℃ to obtain a glass ingot. The thickness of the glass ingot is not less than 80mm. Step 3: After annealing the glass ingots obtained in Step 2 in a mesh belt furnace, cut them into a certain size. Step 4: The glass ingot obtained in Step 3 is subjected to nucleation and crystallization treatment to obtain the final microcrystalline glass ingot. The crystallization process adopts a three-stage nucleation and crystallization process: the first crystallization temperature is 500-650℃, and the holding time is 0.5-10h; the second crystallization temperature is 600-700℃, and the holding time is 0.5-5h; the third crystallization temperature is 700-750℃, and the holding time is 0.5-5h.

2. The method of claim 1, wherein the glass-ceramic ingot is prepared by the steps of: In step 2, the liquidus temperature range of the molten glass is 980-1060℃.

3. The method of claim 2, wherein the glass-ceramic ingot is prepared by the steps of: Step 2: The viscosity of the molten glass meets the following requirements: at 1000℃, the viscosity range is 3000-8000 dPa·S; at 1100℃, the viscosity range is 1000-2000 dPa·S; at 1200℃, the viscosity range is 300-1000 dPa·S; at 1300℃, the viscosity range is 100-300 dPa·S; and at 1400℃, the viscosity range is 10-100 dPa·S.

4. The method of claim 3, wherein the glass-ceramic ingot is prepared by the steps of: The glass ingot obtained in step 2 has an R-angle radius ≤ 10 mm; the transmittance in the visible light band along the thickness direction of the glass ingot is 70-80%, and the haze is ≤ 5; the crystal phase is silicon dioxide.

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

6. A microcrystalline glass characterized by, It is obtained by slicing the microcrystalline glass ingot as described in claim 5.

7. The glass-ceramic according to claim 6, characterized in that, The microcrystalline glass has the following crystal phases: lithium disilicate and / or lithium feldspar and / or lithium monosilicate and / or silicon dioxide, with a crystallinity of 60-90%.

8. A cover glass, characterized by It comprises the microcrystalline glass as described in claim 6 or 7.

9. An electronic device, comprising: It includes the microcrystalline glass as described in claim 6 or 7.

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