High-alumina glass with high transmittance, low viscosity and excellent anti-crystallization performance and method for preparing the same

Abstract

The application discloses high-aluminum glass with high transmittance, low viscosity and excellent anti-crystallization performance and a preparation method thereof, and relates to the technical field of glass. Through multi-component synergistic design, the material formula is reconstructed and optimized, so that the high-aluminum glass produced finally effectively inhibits the crystallization tendency under the premise of high aluminum content, reduces the melting temperature, and simultaneously improves the mechanical properties, chemical resistance, ion exchange performance and high transmittance of the glass, thereby meeting the high-end application requirements of the market.

Description

Technical Field

[0001] This invention relates to the field of glass technology, specifically to high-alumina glass with high transmittance, low viscosity and excellent anti-crystallization properties, and its preparation method. Background Technology

[0002] In today's rapidly developing high-end manufacturing industry, stringent requirements are being placed on the comprehensive performance of materials in fields such as display cover plates, semiconductor substrates, and precision optical components. High-alumina glass, with its high hardness, excellent mechanical strength, good chemical stability, and optical transmittance, has become a core candidate material for these high-end applications. Especially in consumer electronics products such as ultra-thin mobile phones and foldable devices, it can effectively resist scratches and impacts during daily use, ensuring the long-term stable operation of the devices.

[0003] However, the research and production of high-alumina glass still face many technical bottlenecks. Alumina, as a key component for improving the mechanical properties of glass, significantly increases the difficulty of melting when its content is increased. In high-alumina glass, a large amount of high-melting-point alumina forms a dense network structure with silica, resulting in extremely high intrinsic viscosity. This necessitates melting at higher temperatures, increasing energy consumption and production costs, and placing more stringent demands on the high-temperature resistance of the furnace equipment.

[0004] A more prominent problem is the increased risk of crystallization. As the alumina content increases, the glass-forming ability decreases. During melting, forming, and annealing, β-quartz solid solutions, spinel, and anorthite are easily precipitated, leading to glass devitrification, internal defects, and consequently, deterioration of mechanical properties and reduced optical transmittance, severely impacting product yield and reliability. Furthermore, traditional high-alumina glass, while pursuing high alumina content, often struggles to simultaneously achieve low viscosity, high transmittance, and excellent anti-crystallization performance: some formulations sacrifice alumina content to reduce melting difficulty and crystallization risk, but this results in insufficient glass mechanical properties; other formulations, due to unreasonable component design, exhibit an imbalance between high-temperature and low-temperature viscosity control, resulting in a narrow forming window that cannot meet the demands of continuous production.

[0005] In terms of chemical strengthening processes, there is still room for improvement in existing strengthening technologies for high-alumina glass. Traditional strengthening molten salts are mostly based on potassium nitrate alone, which has limited ion exchange efficiency and makes it difficult to form a deep stress layer (DOL) and high surface compressive stress (CS) in a short time. Some composite molten salt formulations lack synergistic design, resulting in problems such as high ion diffusion resistance, easy corrosion and fogging on the glass surface, and insufficient performance stability after strengthening. These issues prevent the full realization of the structural potential of high-alumina glass and limit its application expansion in high-end scenarios.

[0006] Therefore, developing a high-alumina glass preparation technology that optimizes the formulation through multi-component synergistic design, achieves low viscosity, high transmittance, and excellent anti-crystallization performance while ensuring high aluminum content, and is equipped with an efficient chemical strengthening process, is key to solving the pain points of existing technologies and meeting the needs of high-end market applications. It has significant industrial value and application prospects. Summary of the Invention

[0007] The technical problem to be solved by this invention is to overcome the shortcomings of the prior art and provide a high-alumina glass with high transmittance, low viscosity and excellent anti-crystallization performance and its preparation method. Through multi-component synergistic design, the material formula is reconstructed and optimized so that the final high-alumina glass can effectively suppress the tendency of crystallization, reduce the melting temperature, and simultaneously improve the mechanical properties, chemical resistance, ion exchange performance and high transmittance of the glass, so as to meet the needs of high-end applications in the market.

[0008] The technical solution of this invention is as follows:

[0009] On one hand, the present invention provides a method for preparing high-alumina glass with high transmittance, low viscosity and excellent anti-crystallization properties, comprising the following components by mass percentage: SiO2 56-68%, Al2O3 5-15%, K2O 3-6%, Na2O 10-14%, Li2O 0.5-1.5%, MgO 4-7%, CaO 0.01-0.1%, SrO 0.05-2%, B2O3 0.05-1.5%, TiO2 0.05-1%, ZrO2 0.05-1.5%, Y2O3 0.05-2%, SnO2 0.05-0.2%, CeO2 0.05-0.5%; and satisfying the following conditions:

[0010] K₂O + Na₂O + Li₂O = 13.5-22.5%;

[0011] MgO + CaO + SrO = 4-10%;

[0012] B₂O₃ + MgO + SrO = 5-9%;

[0013] TiO2 + ZrO2 + Y2O3 = 0.1-4.5%;

[0014] SnO2 + Y2O3 + CeO2 = 0.01 - 2.5%.

[0015] Preferably, the composition comprises the following components by mass percentage: SiO2 59.49%, Al2O3 13.5%, K2O 4%, Na2O 12.1%, Li2O 1%, MgO 5.5%, CaO 0.01%, SrO 1%, B2O3 0.8%, TiO2 0.2%, ZrO2 0.8%, Y2O3 1%, SnO2 0.15%, CeO2 0.45%;

[0016] K₂O + Na₂O + Li₂O = 17.1%;

[0017] MgO + CaO + SrO = 6.51%;

[0018] B₂O₃ + MgO + SrO = 7.3%;

[0019] TiO2 + ZrO2 + Y2O3 = 2%;

[0020] SnO2 + Y2O3 + CeO2 = 1.6%.

[0021] Compared with existing technologies, in the high-alumina glass of this invention, SiO2 is connected by silicon-oxygen tetrahedra through bridging oxygen, forming a continuous, random, three-dimensional network structure. The strong Si-O covalent bonds (with very high bond energies) give SiO2 extremely high resistance to water, acids, and chemical reagents. SiO2 and ZrO2 work synergistically, Zr... 4+ It is an extremely strong network intermediate, forming [ZrO6] or [ZrO8] polyhedra. These robust polyhedra are dispersed in the SiO2-Al2O3 network, like weld points in a steel skeleton, greatly improving hardness, modulus and chemical durability.

[0022] Sufficient network-modifying cations (such as Na) exist in the glass. + K + Li + Ca 2+ Mg 2+ 、Sr 2+ When Al provides "free oxygen", 3+ It will be tetracoordinated ([AlO4]). - Al2O3 enters the silicon-oxygen network in the form of [AlO4], increasing the network's cross-linking degree and complexity, making the overall glass structure more robust. Al2O3 has a crucial and seemingly contradictory property: it reduces viscosity at high temperatures and increases viscosity at low temperatures. At high temperatures, when [AlO4] enters the network, it breaks the highly interconnected three-dimensional structure of the silicon-oxygen network, transforming it into a less interconnected aluminosilicate network, thereby reducing high-temperature viscosity and facilitating melting and clarification. At low temperatures, Al2O3, as part of the network framework, significantly increases viscosity, making the glass more "short" in the forming and annealing ranges and less prone to deformation.

[0023] High-alumina glass contains a large amount of high-melting-point Al2O3 and SiO2, resulting in extremely high intrinsic viscosity and making it difficult to melt. The introduction of Na2O can drastically reduce the high-temperature viscosity of the glass, allowing the melting, clarifying, and homogenizing processes to take place at temperatures of 1500-1600℃. Na2O directly transforms Al2O3 from the network exogenous material into the network forging material, thereby strengthening the glass network.

[0024] K2O, as a network modifier, can effectively disrupt silicon-oxygen networks. Furthermore, because K... + Due to its large radius, it has poor migration ability in network structures, and its bond-breaking ability is weaker than Na₂O at high temperatures. However, in the low-temperature region (<1000℃), the large volume of K₂O… + The "expanding" and "blocking" effects on the network are more pronounced, thus significantly reducing the low-temperature viscosity of the glass. The introduction of K2O greatly increases the kinetic difficulty of atomic rearrangement to form crystal nuclei, thereby significantly widening the glass forming window and suppressing the precipitation of common crystalline phases (such as β-quartz solid solution, spinel, etc.) in high-alumina glasses. K2O has a high molecular refractive index, which can effectively increase the refractive index of the glass, making the glass appear more "glossy".

[0025] The most crucial positive effect of Li₂O is the "small ion effect." Small Li₂O... + It can embed itself into the gaps in the glass network, acting as both a "filler" and a "pincer." It can maintain or even slightly raise the strain point of the glass, allowing it to withstand higher subsequent processing temperatures and exhibiting superior thermal stability. Furthermore, Li... + The high electric field strength of Li makes it bind more strongly with surrounding oxygen ions, which helps to improve the Young's modulus and Vickers hardness of the glass. + (0.76 Å) and Na + (1.02 Å), K + The radius difference of (1.38 Å) is much greater than that of traditional Na-K exchange, which generates greater compressive stress (CS) during the chemical tempering process of high-alumina glass, resulting in a faster diffusion rate and the formation of a deeper stress layer (DOL) in the same time, thus achieving mechanical strength far exceeding that of traditional soda-lime glass.

[0026] Li₂O, along with other alkali metal oxides such as Na₂O and K₂O, represents the ultimate optimization of the "mixed alkali effect," a dual combination of ion exchange and viscosity control. Li₂O provides high-temperature fluxing and high performance, while Na₂O acts as an auxiliary agent, providing the Na₂O required for chemical tempering. + The combination of these two compounds effectively suppresses the precipitation of lithium crystalline phases because different alkali ions interfere with each other's ordered arrangement. Li₂O + K₂O can also be used to achieve chemical tempering properties for ultra-deep DOLs. This functional combination optimizes chemical strengthening properties and reduces high-temperature viscosity.

[0027] MgO serves as a network modifier for glass, and Mg 2+ With a high electric field strength (large charge / radius ratio), MgO forms strong bonds with non-bridging oxygen, reducing high-temperature viscosity and facilitating glass melting and refining. MgO is the most critical single component for inhibiting crystallization in high-alumina glass. It alters the crystal phase: In the MgO-Al₂O₃-SiO₂ system, it promotes the formation of crystalline phases with lower crystallization rates and higher liquidus temperatures, such as cordierite, rather than cristobalite or mullite, which have strong crystallization driving forces. It increases liquidus viscosity: MgO significantly increases the viscosity of glass at the liquidus temperature (where crystals and liquid coexist). High viscosity greatly hinders the migration and rearrangement of atoms / ions, thus strongly inhibiting crystal growth. MgO is the most effective component for inhibiting Li₂O crystallization. Li₂O provides superior fluxing and chemical tempering capabilities, while MgO provides thermal stability and suppresses the resulting risk of crystallization.

[0028] CaO imparts good water resistance to glass. This is because Ca... 2+ The binding strength with the network is greater than that of Na + Strong, not easily affected by H in water + Displaced. However, in the silicon-rich and aluminum-rich environment of high-alumina glass, Ca... 2+ It readily combines with Al2O3 and SiO2 to form anorthite (CaO·Al2O3·2SiO2) crystals. Therefore, the "micro-calcium principle" is adopted in the design of high-performance high-alumina glass formulations, and the content is strictly controlled at <2.5 wt.%.

[0029] In glasses rich in MgO and Al2O3, the main risk of crystallization comes from magnesium aluminum spinel (MgAl2O4). 2+ The ionic radius (1.18 Å) is much larger than that of Mg. 2+ (0.72 Å) When introduced, it strongly disrupts the kinetics of the ordered arrangement of magnesium and aluminum ions at lattice sites. This huge difference in ion size makes the formation and growth of crystal nuclei extremely difficult, thus significantly improving the thermal stability and resistance to crystallization of the glass. SrO can effectively reduce high-temperature viscosity, resulting in better glass melt flow and facilitating clarification and homogenization.

[0030] The core of the synergistic effect of MgO, CaO, and SrO lies in the complementarity and balance between ionic field strength and ionic radius. MgO resists crystallization but significantly increases viscosity, which is detrimental to melting and forming. CaO effectively neutralizes the excessive viscosity caused by MgO, while the addition of SrO can partially replace CaO, providing superior chemical stability and anti-crystallization ability without excessively sacrificing viscosity. Through the "mixed alkaline earth effect," CaO and SrO effectively block migration channels in the network compared to using either alone, thereby systematically improving the long-term chemical stability and antibacterial properties of the glass. Simultaneously, SrO has high polarizability, and the use of MgO to maintain network strength can increase the refractive index of the glass without excessively increasing dispersion.

[0031] The framework is SiO2-Al2O3, and SrO can be [AlO4]. - It provides a stable charge balance. SrO and Al2O3 do not easily form eutectic or high-driving-force crystalline phases, which makes the high-alumina, high-strontium bicarbonate glass system more stable. MgO is used to build the cornerstone of thermal and mechanical properties, providing the highest strain point and basic network stability. SrO partially replaces MgO, which can significantly improve the solubility and anti-crystallization properties of high-alumina glasses.

[0032] The [BO3] and [BO4] units, when mixed with the [SiO4] and [AlO4] networks, form a more complex multi-component system, increasing the kinetic barrier for atomic rearrangement and crystal nucleation. In the presence of sufficient network modifiers (such as Na2O and MgO), B... 3+ The formation of robust [BO4] tetrahedra is preferentially achieved, cross-linking with the [SiO4] network, leading to increased viscosity, decreased coefficient of thermal expansion, and improved chemical stability. A composite system of "B2O3 + MgO + SrO" is employed. B2O3 acts as a flux, MgO contributes to high strain point and structural stability, and SrO inhibits crystallization, forming a perfect partnership. The synergistic effect of Li2O and B2O3 produces a "super fluxing effect," significantly reducing the melting temperature.

[0033] Ti 4+ It is a strong network intermediate, forming [TiO4], [TiO5], or [TiO6] polyhedra. These robust structural units effectively hinder hydroxide ions (OH-). - ( ) Erosion of the silicon-oxygen network. Both TiO2 and ZrO2 are extremely strong network intermediates that can synergistically and greatly improve the hardness and elastic modulus of glass, achieving performance beyond the norm.

[0034] ZrO2 is one of the most effective oxides for increasing the Vickers hardness of glass. These strong [ZrO] xThe polyhedral structure greatly enhances the glass's resistance to plastic deformation and scratches. The extremely high Zr-O bond energy provides exceptional resistance to acid and alkali corrosion (especially alkali). The introduction of ZrO2 significantly improves the chemical resistance of high-alumina glass, particularly its alkali resistance, elevating it to a top-tier level. Appropriate amounts of ZrO2 also increase the complexity of the glass network, inhibiting the precipitation of certain silicate and aluminate phases (such as cristobalite and mullite).

[0035] Y₂O₃ does not directly form a continuous network, but rather profoundly reconstructs and stabilizes the entire aluminosilicate network through its high field strength and unique coordination mechanism. 3+ The coordination field is extremely complex (usually 6 or 8 coordination), forming [YO x The polyhedral structure is incompatible with [SiO4] and [AlO2]. This fundamental structural difference allows it to "dilute" and "disrupt" the crystallization paths of other easily crystallizable components (such as ZrO2 and TiO2), establishing a more stable amorphous structure. The strong YO bonds effectively resist the erosion of water molecules and hydrogen ions. The introduction of Y2O3 does not form a protective layer on the surface, but rather strengthens the entire network in the bulk phase, making it difficult for corrosive media to penetrate at any location.

[0036] TiO2, ZrO2, and Y2O3 work synergistically to form a "golden triangle" for performance enhancement. As a high-field-strength, high-charge network intermediate, they fundamentally "pin" and "reshape" the glass network, stimulating the top-tier performance of high-alumina glass. 4+ Providing the strongest and most rigid cross-linking points, it acts as the "steel reinforcement" of the high-alumina glass network; Ti 4+ It provides secondary but more polar crosslinking and enhances the network's influence on electronic polarization, thereby improving optical properties. 3+ Due to its large radius and high coordination number, Y₂O₃ provides crosslinking while buffering local stress, preventing the network from becoming brittle due to excessive stiffness and enhancing the mechanical properties of the glass. Y₂O₃ improves infrared transmittance and thermal shock resistance, ZrO₂ provides hardness and corrosion resistance, and TiO₂ adjusts the refractive index and provides UV resistance. Together, these three components ensure stable optical performance under harsh environments.

[0037] The "SnO2-Y2O3-CeO2" ternary synergistic clarifying composite clarifying agent uses Y2O3 as a network structure regulator and synergistic enhancer. Y2O3 is a high-field-strength network intermediate; its [YO6] and other polyhedra can tightly bind with the [SiO4] and [AlO4] networks. This effectively "anchors" SnO2 particles, preventing excessive aggregation or dissolution and distributing them in a finer, more dispersed state. This significantly increases the effective nucleation interface area of ​​SnO2, improving the efficiency and uniformity of bubble nucleation. Simultaneously, the introduction of Y2O3 moderately increases the viscosity of the glass at high temperatures, creating a better working environment for CeO2. Higher high-temperature viscosity means that oxygen bubbles released by CeO2 rise more slowly in the melt, have a longer residence time, and more fully capture and merge microbubbles along the way, resulting in higher clarification efficiency and preventing premature oxygen escape. The three factors work together to achieve a wide temperature range from 1200℃ to 1600℃, with no dead zones, in a stepped clarification process.

[0038] On the other hand, the present invention provides a method for preparing the above-mentioned high-alumina glass with high transmittance, low viscosity and excellent anti-crystallization properties. The glass raw material is melted, clarified, shaped and annealed, and then subjected to primary strengthening. During primary strengthening, a composite molten salt composed of the following components by mass percentage is used: KNO3 90-98%, KOH 1-4%, Al2O3 nanoparticles 0.5-1.5%, Ce(NO3)3 0.05-0.5%, AgNO3 0.1-0.5%. The primary strengthening process is as follows: the glass is immersed in the composite molten salt and treated at 370-420°C for 120-240 min. After primary strengthening, the glass is removed from the composite molten salt, transferred to room temperature air, rinsed and dried.

[0039] Preferably, the composite molten salt is composed of the following components by mass percentage: 96% KNO3, 2.5% KOH, 1% Al2O3 nanoparticles, 0.3% Ce(NO3)3, and 0.2% AgNO3.

[0040] Preferably, the strengthening temperature is 390℃ and the time is 150min.

[0041] In the composite molten salt of this invention, KOH provides OH⁻. - Ions that can react with [AlO4] on the surface of high-alumina glass. - The structure reacts, temporarily breaking strong Al-O bonds, reducing network connectivity, and thus significantly reducing K. + The energy barrier at the glass surface creates conditions for the rapid establishment of high CS.

[0042] Al2O3 nanoparticles: Their function is not dissolution, but rather as a "lattice distortion catalyst." Nanoscale Al2O3 particles adsorb onto the glass surface in molten salt. Their inherent lattice structure induces localized stress fields and defects in the near-surface region of the glass. These defects are K... + The deep diffusion provides additional fast channels, thus significantly deepening the DOL.

[0043] Ce(NO3)3: Acts as an oxidizing agent and surface passivating agent. On one hand, it can oxidize reducing impurities that may exist in molten salt, preventing their reducing corrosion of the glass surface; on the other hand, Ce... 4+ It can form a thin, dense protective oxide layer on the glass surface, effectively suppressing the "acid etching fogging" phenomenon.

[0044] AgNO3: As a functionalizer and a functionalized ion source, it provides long-lasting antibacterial properties to glass. Furthermore, Ce(NO3)3 contains Ce... 3+ / Ce 4+ Its redox buffering capacity is the key chemical equilibrium fulcrum of this formulation, preferentially consuming free oxygen and protecting Ag. + Preventing premature reduction is crucial for maintaining antibacterial function.

[0045] This invention employs a float glass process, the core of which lies in three main stages: high-temperature melting, tin bath float glass forming, and precision annealing.

[0046] Preferably, the specific operation of melting and clarifying is as follows: after the glass raw material enters the furnace, it is pre-melted at 950-1460℃ and held for 30-60 minutes; then melted at 1460-1660℃ for 120-240 minutes; then cooled to 1450-1620℃ for homogenization and clarification of the glass melt and held for 120-210 minutes; and further cooled to 1280-1460℃ for homogenization and cooling of the glass melt and held for 90-120 minutes.

[0047] Preferably, the specific operation of melting and clarifying is as follows: after the glass raw material enters the furnace, it is pre-melted at 1400℃ and held for 45 minutes; then melted at 1650℃ for 180 minutes; then cooled to 1560℃ for homogenization and clarification of the glass melt and held for 150 minutes; and then further cooled to 1320℃ for homogenization and cooling of the glass melt and held for 90 minutes.

[0048] Preferably, the specific annealing operation is as follows: the glass pre-cooling zone temperature is 640-660℃, and the pre-cooling time is 1-4 min; the glass heat soaking zone temperature is 550-620℃, and the heat soaking time is 2-8 min; the glass slow cooling transition zone temperature is 450-570℃, and the transition time is 2-8 min; the glass precision temperature control zone temperature is 500-530℃, and the temperature control time is 2-6 min; the glass rapid cooling zone temperature is 250-400℃, and the temperature control time is 2-5 min; the glass final cooling zone temperature is 20-60℃, and the temperature control time is 1-3 min.

[0049] Preferably, the specific annealing operation is as follows: the glass pre-cooling zone temperature is 660℃, and the pre-cooling time is 3 minutes; the glass heat soaking zone temperature is 606℃, and the soaking time is 6 minutes; the glass slow cooling transition zone temperature is 558℃, and the transition time is 5 minutes; the glass precision temperature control zone temperature is 520℃, and the temperature control time is 4 minutes; the glass rapid cooling zone temperature is 300℃, and the temperature control time is 3 minutes; the glass final cooling zone temperature is 35℃, and the temperature control time is 2 minutes.

[0050] Compared with the prior art, the present invention has the following advantages:

[0051] 1. In the high-alumina glass formula of this invention, characterized by high transmittance, low viscosity, and excellent anti-crystallization properties, Li₂O and other alkali metal oxides (Na₂O, K₂O) form the ultimate optimization of the "mixed alkali effect." In the "B₂O₃+MgO+SrO" composite system, B₂O₃ is responsible for fluxing, MgO for high strain point and structural stability, and SrO for inhibiting crystallization, forming a golden partnership. Simultaneously, Li₂O and B₂O₃ synergistically produce a "super fluxing effect," significantly reducing the melting temperature. TiO₂, ZrO₂, and Y₂O₃ work synergistically to form an "iron triangle," collectively significantly improving the hardness, Young's modulus, and chemical stability of the high-alumina glass. 3+ Its ionic radius and coordination field are between those of the network former and the modifier, allowing it to embed into the local environment of Ti and Zr, forming more complex [Y-Ti-O] or [Y-Zr-O] short-range ordered structures. This structure is extremely stable kinetically, significantly improving mechanical properties. The “SnO2-Y2O3-CeO2” ternary synergistic composite clarifying agent, through the combined action of the three components, achieves step-by-step clarification over a wide temperature range from 1200℃ to 1600℃ without dead zones.

[0052] 2. In the preparation of high-alumina glass, this invention selects the float glass forming process. The manufacturing of high-alumina float glass is a highly integrated continuous process, the core of which lies in three major stages: high-temperature melting, tin bath float glass forming, and precision annealing. During the production process, the heating and cooling are strictly carried out according to the set temperature program, and the heating and cooling rates are strictly controlled. Step cooling is adopted to prevent the rapid cooling of the glass from affecting the surface tensile stress of the glass.

[0053] 3. This invention employs a one-time chemical strengthening process, achieving "virtual multiple strengthening" in the same molten salt bath through programmed temperature control. It innovatively designs a one-time strengthening composite molten salt, realizing mechanical strengthening, surface hardening, chemical stabilization, and antibacterial functions in one stop, which is highly innovative. Detailed Implementation

[0054] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention.

[0055] Examples 1-3 and Comparative Examples 1-10

[0056] The formulations of 0.55 mm thick high-alumina glass in Examples 1-3 and Comparative Examples 1-10 are shown in Table 1-2:

[0057] Table 1. High-alumina glass formulations of Examples 1-3 and Comparative Examples 1-4

[0058]

[0059] Table 2 High-alumina glass formulations for Comparative Examples 5-10

[0060]

[0061] The preparation method of high-alumina glass in Examples 1-3 includes the following steps:

[0062] S1 Melting: After the glass raw material enters the furnace, it is pre-melted at 950-1460℃ and held for 30-60 minutes; then melted at 1460-1660℃ for 120-240 minutes; then cooled to 1450-1620℃ for homogenization and clarification of the glass melt, held for 120-210 minutes; and further cooled to 1280-1460℃ for homogenization and cooling of the glass melt, held for 90-120 minutes. In the furnace, the glass raw material undergoes silicate formation, glass formation, clarification and degassing, homogenization and mark removal, and cooling and viscosity adjustment to finally obtain a clear, uniform glass melt that meets the forming requirements.

[0063] S2 Tin Bath Forming: Molten glass flows into a tin bath filled with N2-H2 protective gas, and naturally spreads on the surface of the molten glass by gravity and surface tension, forming a balanced glass strip with a thickness of 6-7mm. By adjusting the drawing speed and using an edge puller, the pulling force is increased to produce glass, and the product is obtained with the help of the edge puller.

[0064] S3 Annealing Treatment: The glass pre-cooling zone temperature is 640-660℃, with a pre-cooling time of 1-4 minutes; the glass heat soaking zone temperature is 550-620℃, with a holding time of 2-8 minutes; the glass slow cooling transition zone temperature is 450-570℃, with a transition time of 2-8 minutes; the glass precision temperature control zone temperature is 380-420℃, with a temperature control time of 2-6 minutes; the glass rapid cooling zone temperature is 200-250℃, with a temperature control time of 3-5 minutes; the glass final cooling zone temperature is 20-240℃, with a temperature control time of 1-3 minutes. Annealing aims to eliminate internal stress in the glass strip and ensure structural stability.

[0065] S4 cold end processing: The glass is cut into predetermined dimensions using diamond tools to obtain high-alumina glass.

[0066] The process parameters for preparing the high-alumina glass in Examples 1-3 are shown in Table 3:

[0067] Table 3 Process parameters of high-alumina glass in Examples 1-3

[0068]

[0069] The process parameters for the high-alumina glass in Comparative Examples 1-10 are the same as those in Example 1.

[0070] The formulations of the high-alumina glass in Comparative Examples 11-13 are the same as those in Example 1, and the process parameters are shown in Table 4:

[0071] Table 4 Process parameters of high-alumina glass in Comparative Examples 11-13

[0072]

[0073] The performance of the high-alumina glasses prepared in Examples 1-3 and Comparative Examples 1-13 was tested using the following methods:

[0074] Density: Calculated using Archimedes' method, based on the law of buoyancy, by measuring the mass difference of the sample in air and immersed in liquid.

[0075] Young's modulus: Calculated using a universal testing machine by measuring the deflection of the glass beam under bending load and applying elasticity formulas. The formula is as follows:

[0076] E=F×S 3 / 4×b×h 3 ×б;

[0077] In the formula, E: Young's modulus, Pa; F: Load applied at the center of the beam, N; S: Support span, mm; b: Glass width, mm; h: Glass thickness, mm; б: Tensile stress, MPa.

[0078] Bending strength: Tested using a universal testing machine; during sample preparation, the glass is cut into strips approximately 50mm long, 15mm wide, and 5mm thick, and then polished to ensure the sample surface is free of bubbles or cracks. The calculation formula is:

[0079] P=3FL / 2bh 2 ;

[0080] In the formula, P: flexural strength of the specimen, MPa; F: load of the specimen, N; L: span of the support, mm; b: width of the specimen, mm; h: thickness of the specimen, mm.

[0081] Transmittance and refractive index: The Shimadzu UV-2600i UV-Vis spectrophotometer was used to test the glass slide samples. The instrument resolution was 0.1 nm, the scanning interval was 1 nm / scan, and the main wavelength was 550 nm.

[0082] Photoelastic coefficient: The photoelastic coefficient is calculated by using the birefringence effect produced when polarized light passes through a stressed glass sample, analyzing the stress distribution through interference fringes, and combining this with known stress.

[0083] Chemical resistance:

[0084] H2O etching resistance: Clean the glass sample with anhydrous ethanol, immerse it in 250 mL of distilled water, and etch it in a constant temperature water bath at 98±0.5℃ for 60 min.

[0085] Resistance to HCl corrosion: The glass sample was immersed in 250 mL of 5% HCl solution and etched in a constant temperature water bath at 95±0.5℃ for 1440 min.

[0086] Resistance to NaOH corrosion: The glass sample was immersed in 250 mL of 5% NaOH solution and etched in a constant temperature water bath at 95±0.5℃ for 360 min.

[0087] Resistance to HF corrosion: Immerse the glass sample in 250 mL of 10% HF solution and etch it at 20 ± 0.5 °C for 20 min.

[0088] Surface roughness test: Take a glass product measuring 356mm × 416mm and place it on the platform of the stylus-type surface roughness measuring instrument. The sample must not be bent. Let it sit for 5 minutes or longer to ensure that the sample is at the same temperature as the room. Place the probe on the sample, ensuring that the direction of probe movement is consistent with or perpendicular to the direction of sample flow. Determine the measurement position and mark the starting measurement position for testing.

[0089] Glass warpage test: Take a finished glass product with dimensions of 356mm × 416mm. First, determine the tin side and the non-tin side of the glass. Place the sample on a marble platform and rotate it. If it can rotate freely, the top is the tin side, and the side in contact with the marble platform is the air side. Simultaneously, check the warpage against the positioning angles. Gently place the sample on the marble platform and insert a feeler gauge of appropriate size into each of the four corners of the glass sample. Judgment criterion: The maximum value to which the feeler gauge thickness increases until the glass sample just stops moving is the warpage value of that corner. The maximum measurement value at each of the four corners is the actual warpage value (the depth of the feeler gauge insertion into the sample corner edge is <10mm).

[0090] Average linear expansion coefficient and crystallization shrinkage rate were measured using a Linke L45 / 236 thermal dilatometer. A regular 60mm × 40mm round glass rod was prepared. Blank and standard tests were performed using platinum standards under the same testing conditions. The prepared glass rod was vertically placed into a quartz sample tube, fixed at one end and with the other end in contact with a quartz pusher. The heating program was set, with a heating rate of 5℃ / min. The program was started, and the instrument automatically recorded the continuous temperature-sample length curve for data analysis.

[0091] The performance test results of the 0.55 mm thick high-alumina glass prepared in Examples 1-3 and Comparative Examples 1-13 are shown in Tables 5-6:

[0092] Table 5 Performance test results of high-alumina glass in Examples 1-3 and Comparative Examples 1-5

[0093]

[0094] Table 6 Performance test results of high-alumina glass in Comparative Examples 6-13

[0095]

[0096] As shown in Table 5, compared with Example 1, the high-alumina glass prepared in Comparative Example 1 exhibits significantly reduced Young's modulus and alkali resistance, slightly reduced transmittance and refractive index, and a slightly increased linear thermal expansion coefficient. This is mainly because the Al2O3 content was significantly reduced in Example 1, leading to a decrease in the [AlO4] tetrahedral network of the glass, resulting in a decrease in overall network connectivity, density, and rigidity. The weakened network's resistance to elastic deformation and plasticity leads to a significant reduction in the Young's modulus. The attack of strong alkalis (OH-) on the broken Si-O and Al-O bonds is intensified, causing the glass's alkali resistance to decrease from minor corrosion to the appearance of obvious corrosion pits or a hazy layer on the surface. Since Al3O3 has a relatively high molar refractive index, the reduction in Al2O3 content lowers the overall refractive index of the glass.

[0097] Compared to Example 1, the high-alumina glass prepared in Comparative Example 2 showed a decrease in Young's modulus and flexural strength, and a slight increase in the coefficient of linear thermal expansion. This is mainly due to the difference in Li... + The "small ion effect" of Li₂ disappears, negating its "pinning" effect on the network. High-alumina glass networks begin to soften at lower temperatures, resulting in a slight decrease in the strain point and affecting the glass's stability. Simultaneously, the loss of Li₂... + The network reinforcement effect brought about by high field strength will reduce the glass's resistance to elastic deformation (Young's modulus) and flexural strength to varying degrees. Losing Li + This makes the glass network structure relatively "loose," resulting in greater atomic vibration amplitude when heated, which leads to an increase in the glass's linear thermal expansion coefficient and affects its properties.

[0098] Compared to Example 1, the high-alumina glass prepared in Comparative Example 3 showed a significant decrease in its resistance to crystallization. This is mainly due to the loss of Sr in the glass. 2+ With Mg 2+ The resulting strong "mixed alkaline earth effect" fails to disrupt the orderly arrangement of magnesium and aluminum ions, leading to an increased crystallization driving force for crystalline phases such as magnesium aluminum spinel, thereby reducing the thermal stability and resistance to crystallization of the glass. SrO also increases the high-temperature viscosity of the glass, reducing the fluidity of the molten glass.

[0099] Compared to Example 1, the high-alumina glass prepared in Comparative Example 4 exhibited a significantly increased viscosity and decreased flexural strength. This is mainly because B2O3 is an extremely strong co-solvent; without adding B2O3, to achieve the same clarifying effect in the high-alumina glass, the melting temperature would need to be increased by 100°C or higher, leading to a substantial increase in viscosity and making melting more difficult. The absence of B2O3 also results in a lack of a "buffer" network within the glass, making microcracks more prone to propagate and reducing flexural strength.

[0100] Compared to Example 1, the high-alumina glass prepared in Comparative Example 5 exhibited a significantly increased viscosity and deteriorated surface microstructure. This is primarily due to the loss of the strongest high-temperature flux (Li2O) and the highly efficient flux (B2O3), resulting in an extreme increase in the glass's high-temperature viscosity. The melting temperature may need to be raised from the conventional 1600-1650℃ to 1750℃ or even higher, far exceeding the limits of the furnace. At such high viscosity, bubbles cannot escape, the homogenization reaction is difficult to carry out, and the glass will be filled with bubbles, streaks, and inclusions, leading to a complete deterioration in roughness and warpage properties.

[0101] As shown in Table 6, compared with Example 1, the high-alumina glass prepared in Comparative Example 6 exhibited significantly reduced Young's modulus and flexural strength, drastically deteriorated alkali resistance, slightly decreased acid resistance and water resistance, and a lower refractive index. This is mainly because ZrO2 is one of the most effective oxides for improving the Vickers hardness of glass. xThe polyhedrons greatly enhance the glass's resistance to plastic deformation and scratches. The Zr-O bond energy is extremely high, providing exceptional resistance to acid and alkali (especially alkali) corrosion. Its absence makes the glass highly susceptible to corrosion in alkaline environments.

[0102] Compared to Example 1, the high-alumina glass prepared in Comparative Example 7 exhibited decreased Young's modulus, flexural strength, alkali resistance, refractive index, and transmittance. This is mainly because ZrO2, TiO2, and Y2O3 are often referred to as the "golden triangle" of high-performance glasses. Furthermore, without their addition, the glass abandons the pursuit of ultimate mechanical properties, optical properties, and superior chemical stability.

[0103] Compared to Example 1, the high-alumina glass prepared in Comparative Example 8 showed decreased transmittance, reduced refractive index, and worse surface roughness. This is mainly because SnO2 exists in equilibrium at high temperatures: SnO2... SnO + 1 / 2O₂↑ provides heterogeneous nucleation sites, promoting the coalescence of small bubbles. Without adding SnO₂, this efficient physicochemical clarification pathway is lost. Furthermore, SnO₂ can absorb some ultraviolet light through its electronic structure and can slightly interfere with Fe through electrostatic interactions. 3+ With Ti 4+ The coupling reduces the resulting yellow tint and increases the glass's transmittance and refractive index.

[0104] Compared to Example 1, the high-alumina glass prepared in Comparative Example 9 exhibited reduced transmittance, lower refractive index, and worse surface roughness. This is primarily because CeO2 decomposes at temperatures above 1400°C (4CeO2→2Ce2O3+O2↑), releasing oxygen to remove the most difficult-to-remove microbubbles. After removal, the glass relies on other clarifying agents (such as SnO2) for final clarification, resulting in a decreased ability to remove microbubbles and "regenerated bubbles."

[0105] Compared to Example 1, the high-alumina glass prepared in Comparative Example 10 exhibited a broken clarification chain, a significant decrease in glass transmittance, incomplete coverage of bubble size and type, and an exponentially increased risk of incomplete clarification. The color control defenses completely collapsed. The glass color became extremely sensitive to the iron and titanium impurities in the raw materials, easily producing uncontrollable yellow, green, or composite hues. Furthermore, when high-temperature clarification or homogenization was required, the glass itself was more prone to structural changes (such as phase separation and initial crystallization), which in turn interfered with the removal of residual bubbles and chemical homogeneity, creating a vicious cycle.

[0106] Compared to Example 1, the high-alumina glass prepared in Comparative Example 11 exhibited reduced Young's modulus, flexural strength, transmittance, uniformity, and chemical stability. This was primarily due to insufficient melting temperature during the production process, resulting in a mismatch in the thermal expansion coefficients of unmelted quartz and other hard inclusions with the glass matrix. This mismatch created significant localized stress concentration points around these inclusions, becoming the source of crack initiation and propagation. Bubbles and unmelted materials directly scatter and absorb light. Chemical inhomogeneity led to different refractive indices in different regions, causing disordered light refraction. This resulted in decreased transmittance and uniformity. The uneven expansion and contraction of chemically inhomogeneous regions during temperature changes generated internal stress. Regions where the network was not fully formed were more susceptible to corrosion by water or acid, further reducing the glass's chemical stability.

[0107] Compared to Example 1, the high-alumina glass prepared in Comparative Example 12 exhibited reduced bending strength, a lower coefficient of linear thermal expansion, non-uniform refractive index, and decreased chemical stability (reduced surface corrosion resistance). This is primarily because the internal structure of the glass is in a relaxed state after high-temperature forming. If the cooling is too rapid or the annealing temperature is insufficient, the temperature gradient between the glass surface and interior will lead to uneven shrinkage, generating permanent internal stress (thermal stress). This results in reduced bending strength and increased brittle fracture; in severe cases, it may even spontaneously shatter. The internal structure of the glass has not reached equilibrium, leading to a decrease in the local coefficient of thermal expansion. Furthermore, if the temperature does not meet the annealing requirements during cooling, the internal density and structure of the glass will not fully relax, resulting in local refractive index fluctuations. The glass may exhibit optical distortion, streaks, or haze, affecting light transmittance and image quality.

[0108] Compared to Example 1, the high-alumina glass prepared in Comparative Example 13 exhibited birefringence, decreased transmittance, severely deteriorated mechanical properties, and reduced chemical stability. This was mainly due to improper control of the stepped cooling process, which led to uneven stress distribution in the thickness or planar direction of the glass plate / part, further reducing its effective load-bearing capacity and causing severe deterioration of mechanical properties. The refractive index of glass is directly related to its density. Improper stepped cooling temperature resulted in different degrees of structural relaxation in different regions, causing density fluctuations. This density unevenness inevitably leads to uneven refractive index, causing light scattering and distortion, affecting image quality. Permanent internal stress causes the glass to become an anisotropic medium, resulting in birefringence when light passes through it, and colored fringes (stress spots) observed under a polarizing microscope. 3+ It typically enters the network in the form of [AlO4] tetrahedra, but requires alkali metal ions (such as Na) + This is to balance the charge. If the stepped cooling (especially the steps in the high-temperature zone) is insufficient, the network structure fails to achieve optimal densification and homogenization. This leads to a decrease in the water, acid, and alkali resistance of the high-alumina glass, making the surface prone to corrosion, weathering, and the appearance of hazy white spots.

[0109] Examples 4-6 and Comparative Examples 14-17

[0110] The high-alumina glasses prepared in Examples 4-6 and Comparative Examples 14-17 were chemically strengthened. The strengthening process was as follows: First, the glass was preheated to remove moisture and prevent thermal shock. Then, the glass was immersed in a composite molten salt and treated at 370-420°C for 120-180 min. After the first strengthening, the glass was removed from the composite molten salt and transferred to room temperature air to prevent relaxation at high temperatures. It was then vigorously rinsed with flowing hot water to dissolve and remove nitrate crystals adhering to the surface, followed by rinsing with deionized water and drying. The chemical strengthening conditions are shown in Table 7.

[0111] Table 7 Chemical strengthening conditions for the high-alumina glasses prepared in Examples 4-6 and Comparative Examples 14-17

[0112]

[0113] The performance of the chemically strengthened high-alumina glasses of Examples 4-6 and Comparative Examples 14-17 was tested using the following methods:

[0114] CS, DOL, CT: The values ​​were measured using FSM-6000 and SLP-IV instruments.

[0115] Drop ball test: The test is conducted using a drop ball tester. The glass is fixed horizontally on a rigid base, and the ball is released through an electromagnetic device to fall freely and impact the center of the glass or a designated position. The test is performed every 5cm. The weight of the ball is 110g. The test is performed 3 times at each height to determine the drop height.

[0116] Antibacterial test: Cut the glass into standard sizes of 50mm × 50mm, maintaining a consistent thickness. Clean the samples sequentially with acetone, anhydrous ethanol, and deionized water using ultrasonic cleaning for 15 minutes each. Immerse the samples in 75% (v / v) medical alcohol for 30 minutes, then remove and air dry in a clean bench with sterile air. After sterilization, place the samples into sterile petri dishes using sterile forceps. Use a pipette to transfer 0.1 mL of the prepared Staphylococcus aureus and Escherichia coli suspension, and drop it vertically into the center of the sample. Gently cover the droplet with the glass and cover the petri dish. A control sample is also prepared. Set the incubation conditions (temperature 35±1℃, relative humidity >90%, incubation time 24±1h), and calculate the antibacterial rate of the glass using the following formula: Antibacterial rate R = [(C0-C) / C0] × 100%; where: C: viable count of the antibacterial sample, C0: average viable count of the control sample.

[0117] The test results are shown in Table 8:

[0118] Table 8 Performance test results of chemically strengthened high-alumina glasses in Examples 4-6 and Comparative Examples 14-17

[0119]

[0120] As shown in Table 8, compared with Example 4, the high-alumina glass of Comparative Example 14 exhibits lower CT, CS, and DOL, lower bending strength, and worse falling ball impact resistance. This is mainly because Comparative Example 14 uses only 100% KNO3 as the primary strengthening tempering molten salt, resulting in the absence of KOH in the molten salt and thus no OH groups. - It cannot attack and break the Si-O-Si bond (≡Si-O-Si≡+OH). - → ≡Si-OH+ - O-Si≡) causes the ion exchange reaction to remain on the surface and in the shallow layer, requiring an extremely long processing time to achieve a certain DOL, and the upper limit of CS is limited by the intrinsic diffusion rate. KOH and Al2O3 nanoparticles work synergistically, with Al2O3 nanoparticles embedding and reinforcing the network opened by KOH, preventing the surface of the reinforced glass from weakening due to excessive corrosion.

[0121] Compared to Example 4, the high-alumina glass of Comparative Example 15 showed decreased CT and CS, slightly increased DOL, and worsened bending strength and falling ball impact resistance. This is mainly because the primary strengthening tempering molten salt of Comparative Example 15 lacked Al2O3 nanoparticles and Ce(NO3)3. Without Al2O3, the strength and toughness of the glass rely entirely on a uniform compressive stress layer. In conditions such as sharp impacts and frictional wear that lead to crack initiation, its performance is inferior to that of the high-alumina glass strengthened by composite molten salt. Ce(NO3)3 effectively removes free oxygen from the molten salt, inhibiting excessive decomposition of KNO3 and harmful oxidation of the glass surface. By maintaining a more stable redox potential, it prevents Fe... 2+ The color-causing ions are oxidized, keeping the glass colorless and transparent.

[0122] Compared to Example 4, the high-alumina glass of Comparative Example 16 exhibits reduced CS, lower bending strength, and worse falling ball impact resistance. This is primarily because the primary strengthening tempering molten salt of Comparative Example 16 lacks Ce(NO3)3. The absence of Ce(NO3)3 causes the free oxygen concentration in the molten salt to continuously rise and fluctuate, accelerating the decomposition of the molten salt itself and resulting in severe and uncontrollable oxidation of the glass surface. In this weakened structure, not only K... + The exchange efficiency will be affected, and the K that has already been exchanged will also be affected. + It is also easier for it to migrate out later, leading to compressive stress relaxation (aging) and easy weathering of the surface to form white spots.

[0123] Compared to Example 4, the mechanical strengthening of the high-alumina glass in Comparative Example 17 did not change significantly, but Ce... 3+ Through its own variable valence properties, it provides benefits to the entire system (especially the reactive Ag). +It provides a stable chemical environment with low oxidation potential, enabling the glass to maintain its antibacterial function without fading or failure, thus protecting the glass surface.

[0124] In summary, in the production of high-alumina glass with high transmittance, low viscosity, and excellent anti-crystallization properties, the design of the raw material formulation and process, as well as the selection and proportioning of chemical strengthening processes and molten salts, all have a significant impact on the glass's forming ability, properties, and overall performance after strengthening. This invention strictly adheres to the set temperature program for heating and cooling, with rigorous control over the heating and cooling rates. A stepped cooling method is employed to prevent rapid cooling from affecting the glass's surface tensile stress. The high-alumina glass prepared by this invention possesses excellent physical and mechanical properties, optical properties, chemical resistance, surface and microscopic properties, and thermal analysis performance. Furthermore, the high-alumina glass of this invention employs a single-stage strengthening process, innovatively designing composite molten salts and specific tempering temperatures and times, resulting in high impact resistance, high strength, high CS and CT values, and excellent antibacterial properties, demonstrating excellent application prospects.

Claims

1. High-alumina glass having high transmittance, low viscosity and excellent devitrification resistance, characterized in that, The composition includes the following components by mass percentage: SiO2 56-68%, Al2O3 5-15%, K2O 3-6%, Na2O 10-14%, Li2O 0.5-1.5%, MgO 4-7%, CaO 0.01-0.1%, SrO 0.05-2%, B2O3 0.05-1.5%, TiO2 0.05-1%, ZrO2 0.05-1.5%, Y2O3 0.05-2%, SnO2 0.05-0.2%, CeO2 0.05-0.5%; and satisfies the following conditions: K₂O + Na₂O + Li₂O = 13.5-21.5%; MgO + CaO + SrO = 4.06-9.1%; B₂O₃ + MgO + SrO = 5-9%; TiO2 + ZrO2 + Y2O3 = 0.15-4.5%; SnO2 + Y2O3 + CeO2 = 0.15 - 2.5%.

2. The high-alumina glass having high transmittance, low viscosity and excellent devitrification resistance according to claim 1, wherein The composition includes the following components by mass percentage: SiO2 59.49%, Al2O3 13.5%, K2O 4%, Na2O 12.1%, Li2O 1%, MgO 5.5%, CaO 0.01%, SrO 1%, B2O3 0.8%, TiO2 0.2%, ZrO2 0.8%, Y2O3 1%, SnO2 0.15%, CeO2 0.45%; K₂O + Na₂O + Li₂O = 17.1%; MgO + CaO + SrO = 6.51%; B₂O₃ + MgO + SrO = 7.3%; TiO2 + ZrO2 + Y2O3 = 2%; SnO2 + Y2O3 + CeO2 = 1.6%.

3. The method of producing a high-alumina glass having high transmittance, low viscosity and excellent devitrification resistance according to claim 1 or 2, characterized in that, After melting, clarifying, shaping, and annealing, the glass raw material undergoes primary strengthening. During primary strengthening, a composite molten salt composed of the following components by mass percentage is used: KNO3 90-98%, KOH 1-4%, Al2O3 nanoparticles 0.5-1.5%, Ce(NO3)3 0.05-0.5%, and AgNO3 0.1-0.5%. The primary strengthening process is as follows: the glass is immersed in the composite molten salt and treated at 370-420℃ for 120-240 minutes. After primary strengthening, the glass is removed from the composite molten salt, transferred to room temperature air, rinsed, and dried.

4. The method of producing a high-alumina glass having high transmittance, low viscosity and excellent devitrification resistance according to claim 3, characterized by, The composite molten salt is composed of the following components by mass percentage: KNO3 96%, KOH 2.5%, Al2O3 nanoparticles 1%, Ce(NO3)3 0.3%, and AgNO3 0.2%.

5. The method for preparing high-alumina glass with high transmittance, low viscosity and excellent anti-crystallization properties as described in claim 3, characterized in that, The initial strengthening temperature was 390℃, and the time was 150 minutes.

6. The method for preparing high-alumina glass with high transmittance, low viscosity and excellent anti-crystallization properties as described in claim 3, characterized in that, The specific operation of melting and clarifying is as follows: After the glass raw material enters the furnace, it is pre-melted at 950-1460℃ and held for 30-60 minutes; then melted at 1460-1660℃ for 120-240 minutes; then cooled to 1450-1620℃ for homogenization and clarification of the glass melt and held for 120-210 minutes; and then further cooled to 1280-1460℃ for homogenization and cooling of the glass melt and held for 90-120 minutes.

7. The method for preparing high-alumina glass with high transmittance, low viscosity and excellent anti-crystallization properties as described in claim 6, characterized in that, The specific operation of melting and fining is as follows: after the glass raw materials enter the kiln, pre-melting is carried out at 1400 DEG C for 45 min; melting is carried out at 1650 DEG C for 180 min; then the temperature is decreased to 1560 DEG C, homogenization and fining of the glass liquid are carried out, and the temperature is kept for 150 min; further decreasing the temperature to 1320 DEG C, homogenization and cooling of the glass liquid are carried out, and the temperature is kept for 90 min.

8. The method for preparing high-alumina glass with high transmittance, low viscosity and excellent anti-crystallization properties as described in claim 3, characterized in that, The specific operation of annealing is as follows: the temperature of the pre-cooling zone of the glass is 640-660 DEG C, the pre-cooling time is 1-4 min; the temperature of the temperature-holding zone of the glass is 550-620 DEG C, the temperature-holding time is 2-8 min; the temperature of the slow-cooling transition zone of the glass is 450-570 DEG C, the transition time is 2-8 min; the temperature of the precise temperature-control zone of the glass is 500-530 DEG C, the temperature-control time is 2-6 min; the temperature of the fast-cooling zone of the glass is 250-400 DEG C, the temperature-control time is 2-5 min; the temperature of the final-cooling zone of the glass is 20-60 DEG C, the temperature-control time is 1-3 min.

9. The method for preparing high-alumina glass with high transmittance, low viscosity and excellent anti-crystallization properties as described in claim 8, characterized in that, The specific operation of annealing is as follows: the temperature of the pre-cooling zone of the glass is 660 DEG C, the pre-cooling time is 3 min; the temperature of the temperature-holding zone of the glass is 606 DEG C, the temperature-holding time is 6 min; the temperature of the slow-cooling transition zone of the glass is 558 DEG C, the transition time is 5 min; the temperature of the precise temperature-control zone of the glass is 520 DEG C, the temperature-control time is 4 min; the temperature of the fast-cooling zone of the glass is 300 DEG C, the temperature-control time is 3 min; the temperature of the final-cooling zone of the glass is 35 DEG C, the temperature-control time is 2 min.

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