Alkali-free glass and use thereof

Abstract

The application provides an alkali-free glass with a low thermal expansion coefficient, high transmittance, high strain point, high rigidity and optical-grade internal quality and application thereof. The application optimizes the glass composition, so that each component in the alkali-free glass meets specific content relationship requirements, and the glass liquid viscosity and the composition meet a specific relationship, and the synergistic effect of the components is utilized, so that the internal bubble defect problem and the transmittance reduction problem in the glass melting process are significantly improved while the alkali-free glass prepared has excellent properties such as a low thermal expansion coefficient, high strain point and high rigidity, and the alkali-free glass prepared meets the optical-grade internal quality and high transmittance.

Description

Technical Field

[0001] This application relates to the field of glass materials technology, and in particular to an alkali-free glass and its applications. Background Technology

[0002] With the ever-increasing demand for larger storage capacity, hard disk drives (HDDs) are evolving towards higher storage density and faster read / write speeds. This places extremely high demands on hard disk platters: excellent surface flatness, nanometer-level surface roughness, superior mechanical rigidity, good thermal stability, and crucial optical performance.

[0003] In existing technologies, aluminum substrates, due to their high coefficient of thermal expansion, insufficient rigidity, and optical opacity, are no longer sufficient to meet the requirements of next-generation hard disk technologies (such as heat-assisted magnetic recording, HAMR). Alkali-free high-strain-point glass substrates, with their advantages of low coefficient of thermal expansion, high rigidity, and high transmittance, have become the ideal choice for high-end, high-capacity HDDs. Summary of the Invention

[0004] However, this application finds that while meeting the requirements of low thermal expansion coefficient, high strain point, and high rigidity, the melting difficulty of alkali-free glass increases significantly. Specifically, the excessively high viscosity of the molten alkali-free glass makes it difficult to completely eliminate internal air bubbles during the melting process, resulting in defects within the produced alkali-free glass. If this alkali-free glass is used in magnetic recording media, it increases the risk of magnetic head impact, potentially leading to damage to the magnetic recording media. Furthermore, under ultra-high temperature melting conditions, the clarifying agent SnO2 readily reacts with the platinum-rhodium crucible, causing a decrease in the transmittance of the alkali-free glass. If this alkali-free glass is used in magnetic recording media, it will severely interfere with the writing laser signal, failing to provide nanometer-level precise positioning for the magnetic head, ultimately causing write errors on the hard drive tracks.

[0005] In view of this, there is an urgent need to develop an alkali-free glass substrate that has a low coefficient of thermal expansion, a high strain point, high rigidity, optical-grade internal quality, and excellent visible light transmittance, so as to solve the problems of melting defects and reduced transmittance at the same time.

[0006] The purpose of this application is to provide an alkali-free glass and its application, which gives the alkali-free glass a low coefficient of thermal expansion, high transmittance, high strain point, high rigidity and optical-grade internal quality.

[0007] In a first aspect, this application provides an alkali-free glass, wherein the composition of the alkali-free glass, based on the molar percentage of oxides, comprises: 67 mol%~71 mol% SiO2, 13 mol%~16 mol% Al2O3, 0.7 mol%~1.2 mol% B2O3, 3 mol%~4 mol% BaO, 4 mol%~7.5 mol% CaO, 4.5 mol%~8 mol% MgO, 0.4 mol%~1 mol% SrO, 0 mol%~0.2 mol% Y2O3+La2O3, and 0.01 mol%~0.2 mol% SnO2;

[0008] The alkali-free glass satisfies the following:

[0009] ,

[0010] Where: η 1650 The viscosity of the alkali-free glass at 1650°C is expressed in poise; η0 is the viscosity constant, with a value of 100 poise; X Al X represents the molar percentage of Al2O3 in the alkali-free glass. B X represents the molar percentage of B2O3 in the alkali-free glass. Mg X represents the molar percentage of MgO in the alkali-free glass. Ca X represents the molar percentage of CaO in the alkali-free glass. Ba X represents the molar percentage of BaO in the alkali-free glass. Sn The molar percentage of SnO2 in the alkali-free glass; α is the effective factor of SnO2 in suppressing bubbles, with a value of 0.8; K Sn The value is 0.1, representing the retardation constant. This application discovers that the bubble defects and reduced transmittance during the melting of alkali-free glass are closely related to the glass composition and the viscosity of the molten glass. Based on this discovery, this application optimizes the glass composition to ensure that each component in the alkali-free glass meets specific content requirements and that the viscosity of the molten glass satisfies a specific relationship with its composition. By utilizing the synergistic effect between the components, while ensuring that the prepared alkali-free glass possesses excellent properties such as a low coefficient of thermal expansion, a high strain point, and high rigidity, the internal bubble defects and reduced transmittance during the glass melting process are significantly improved, resulting in alkali-free glass that meets optical-grade internal quality and high transmittance standards.

[0011] In some embodiments of this application, the alkali-free glass satisfies:

[0012] ,

[0013] Wherein: T 350P X is the temperature at which the viscosity of the alkali-free glass melt is 350 poise; SnX represents the molar percentage of SnO2 in the alkali-free glass. Al X represents the molar percentage of Al2O3 in the alkali-free glass. Si This represents the molar percentage of SiO2 in the alkali-free glass. In this application, by employing an embodiment that satisfies this relationship, alkali-free glass with superior transmittance can be obtained.

[0014] In some embodiments of this application, the composition of the alkali-free glass, based on the molar percentage of oxides, satisfies the following: 14.5 mol% ≤ MgO + CaO + SrO + BaO ≤ 18.1 mol%; and / or, 0.3 ≤ MgO / (MgO + CaO + SrO + BaO) ≤ 0.5; and / or, 1.8 ≤ 10 × Al₂O₃ / SiO₂ ≤ 2.3; and / or, 0.95 ≤ (MgO + CaO + SrO + BaO) / Al₂O₃ ≤ 1.32; and / or, 0 ≤ Y₂O₃ + La₂O₃ ≤ 0.19 mol%; and / or, 5.1 ≤ 100 × B₂O₃ / Al₂O₃ ≤ 7.8. In this application, by controlling the content relationship of each oxide, it is advantageous to obtain alkali-free glass with a low coefficient of thermal expansion, high transmittance, high strain point, high rigidity, and optical-grade internal quality.

[0015] In some embodiments of this application, the composition of the alkali-free glass, based on the molar percentage of oxides, satisfies the following: SiO2 67.12 mol%~70.36 mol%; and / or, Al2O3 13.5 mol%~15.5 mol%, preferably 13.76 mol%~15.33 mol%; and / or, B2O3 0.71 mol%~1.13 mol%; and / or, BaO 3.14 mol%~4.0 mol%; and / or, CaO 4.35 mol%~7.35 mol%; and / or, MgO 4.87 mol%~7.55 mol%; and / or, SrO 0.46 mol%~0.88 mol%; and / or, SnO2 0.08 mol%~0.2 mol%.

[0016] In some embodiments of this application, the composition of the alkali-free glass, based on the molar percentage of oxides, includes: 67.19 mol%~67.92 mol% SiO2, 13.78 mol%~13.88 mol% Al2O3, 0.8 mol%~1.06 mol% B2O3, 3.2 mol%~3.92 mol% BaO, 6.25 mol%~7.12 mol% CaO, 5.88 mol%~7.23 mol% MgO, 0.51 mol%~0.85 mol% SrO, 0.04 mol%~0.08 mol% Y2O3+La2O3, and 0.13 mol%~0.16 mol% SnO2; and the alkali-free glass satisfies:

[0017] . In this application, the implementation scheme is adopted, which ensures that excellent characteristics such as low coefficient of thermal expansion, high strain point and high rigidity are met, while also facilitating the production of alkali-free glass with fewer bubble defects and higher transmittance.

[0018] In some embodiments of this application, the alkali-free glass satisfies:

[0019] ,

[0020] Wherein: T 350P X is the temperature at which the viscosity of the alkali-free glass melt is 350 poise. Sn X represents the molar percentage of SnO2 in the alkali-free glass. Al X represents the molar percentage of Al2O3 in the alkali-free glass. Si The molar percentage of SiO2 in the alkali-free glass; and / or, in terms of the molar percentage of oxides, the composition of the alkali-free glass satisfies: 16.9 mol% ≤ MgO + CaO + SrO + BaO ≤ 18.1 mol%; and / or, in terms of the molar percentage of oxides, the composition of the alkali-free glass satisfies: 0.32 ≤ MgO / (MgO + CaO + SrO + BaO) ≤ 0.41; and / or, in terms of the molar percentage of oxides, the composition of the alkali-free glass satisfies: 2 ≤ 10 × Al2O3 / SiO2 ≤ 2.1; and / or, in terms of the molar percentage of oxides, the composition of the alkali-free glass satisfies: 1.2 ≤ (MgO + CaO + SrO + BaO) / Al2O3 ≤ 1.32; and / or, in terms of the molar percentage of oxides, the composition of the alkali-free glass satisfies: 5.8 ≤ 100 × B2O3 / Al2O3 ≤ 7.7.

[0021] In some embodiments of this application, the composition of the alkali-free glass, based on the molar percentage of oxides, includes: 67.55 mol%~69.79 mol% SiO2, 13.76 mol%~15.13 mol% Al2O3, 0.72 mol%~1.11 mol% B2O3, 3.16 mol%~3.88 mol% BaO, 4.56 mol%~6.55 mol% CaO, 4.98 mol%~7.12 mol% MgO, 0.46 mol%~0.87 mol% SrO, 0 mol%~0.17 mol% Y2O3+La2O3, and 0.1 mol%~0.14 mol% SnO2; and the alkali-free glass satisfies:

[0022] . In this application, the adoption of this implementation scheme is beneficial to obtaining alkali-free glass with a higher strain point, lower coefficient of thermal expansion, and higher modulus.

[0023] In some embodiments of this application, the alkali-free glass satisfies:

[0024] ,

[0025] Wherein: T 350P X is the temperature at which the viscosity of the alkali-free glass melt is 350 poise. Sn X represents the molar percentage of SnO2 in the alkali-free glass. Al X represents the molar percentage of Al2O3 in the alkali-free glass. Si The molar percentage of SiO2 in the alkali-free glass; and / or, in terms of the molar percentage of oxides, the composition of the alkali-free glass satisfies: 14.5 mol% ≤ MgO + CaO + SrO + BaO ≤ 16.5 mol%; and / or, in terms of the molar percentage of oxides, the composition of the alkali-free glass satisfies: 0.3 ≤ MgO / (MgO + CaO + SrO + BaO) ≤ 0.46; and / or, in terms of the molar percentage of oxides, the composition of the alkali-free glass satisfies: 1.9 ≤ 10 × Al2O3 / SiO2 ≤ 2.3; and / or, in terms of the molar percentage of oxides, the composition of the alkali-free glass satisfies: 0.95 ≤ (MgO + CaO + SrO + BaO) / Al2O3 ≤ 1.2; and / or, in terms of the molar percentage of oxides, the composition of the alkali-free glass satisfies: 5.1 ≤ 100 × B2O3 / Al2O3 ≤ 7.7.

[0026] In some embodiments of this application, the alkali-free glass satisfies:

[0027] ; and / or,

[0028] The alkali-free glass satisfies the following:

[0029] .

[0030] In some embodiments of this application, the alkali-free glass satisfies:

[0031] .

[0032] In some embodiments of this application, the strain point of the alkali-free glass is ≥745℃; preferably, the strain point of the alkali-free glass is 745℃~765℃; more preferably, the strain point of the alkali-free glass is 755℃~765℃; and / or,

[0033] The alkali-free glass has a softening point ≥1025℃, preferably, the softening point of the alkali-free glass is 1025℃~1050℃; and / or,

[0034] The liquidus temperature of the alkali-free glass is ≤1085℃; and / or,

[0035] The coefficient of thermal expansion of the alkali-free glass is 33 × 10⁻⁶ in the temperature range of 20℃ to 300℃. -7 / ℃~45×10 -7 / ℃, preferably, the coefficient of thermal expansion is 33×10⁻⁶℃. -7 / ℃~40×10 -7 / ℃; and / or,

[0036] The alkali-free glass has a Young's modulus ≥ 83 GPa, preferably 84 GPa to 91 GPa, and more preferably 85 GPa to 91 GPa.

[0037] In some embodiments of this application, the melt viscosity η of the alkali-free glass at 1650°C is... 1650 ≤200 poises, preferably, η 1650 For 150 to 200 poises; and / or,

[0038] The temperature T corresponding to the viscosity of the alkali-free glass melt being 350 poise. 350P ≤1635℃, preferably, T 350P The temperature range is 1600℃ to 1635℃.

[0039] In some embodiments of this application, when the thickness of the alkali-free glass is (0.5±0.01) mm, the transmittance of the alkali-free glass at a wavelength of 360 nm is ≥89%; preferably, when the thickness of the alkali-free glass is (0.5±0.01) mm, the transmittance of the alkali-free glass at a wavelength of 360 nm is ≥90%; and / or,

[0040] When the thickness of the alkali-free glass is (0.5±0.01) mm and the surface area of ​​the main surface is (100±1) cm², there are no bubbles with a diameter greater than 0.02 mm in the alkali-free glass, and the number of bubbles with a diameter less than or equal to 0.02 mm does not exceed 15.

[0041] Secondly, this application provides a glass substrate for magnetic storage media, which includes the alkali-free glass described in any embodiment of the first aspect of this application.

[0042] Thirdly, this application provides a magnetic storage device, which includes the alkali-free glass described in any embodiment of the first aspect of this application or a glass substrate for magnetic storage media described in the second aspect of this application.

[0043] Fourthly, this application provides a mechanical hard disk comprising the alkali-free glass described in any embodiment of the first aspect of this application.

[0044] Fifthly, this application provides a glass substrate for a display, which includes the alkali-free glass described in any embodiment of the first aspect of this application.

[0045] In a sixth aspect, this application provides a glass article comprising the alkali-free glass described in any embodiment of the first aspect of this application.

[0046] The beneficial effects of this application are:

[0047] This application optimizes the glass composition to ensure that each component in the alkali-free glass meets specific content requirements and that the viscosity of the molten glass satisfies a specific relationship with its composition. By utilizing the synergistic effect of the components, while ensuring that the prepared alkali-free glass possesses excellent properties such as a low coefficient of thermal expansion, a high strain point, and high rigidity, it significantly improves the problems of internal bubble defects and reduced transmittance during the glass melting process, enabling the obtained alkali-free glass to meet optical-grade internal quality and high transmittance.

[0048] Of course, implementing any product or method of this application does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these accompanying drawings.

[0050] Figure 1 This is a partial schematic diagram of the alkali-free glass product prepared in Example 2 placed against a black background.

[0051] Figure 2 This is a partial schematic diagram of the alkali-free glass product prepared in Example 17 placed against a black background.

[0052] Figure 3 A partial schematic diagram of the alkali-free glass product prepared in Comparative Example 2 placed against a black background;

[0053] Figure 4 This is a partial schematic diagram of the 20mm thick alkali-free glass product prepared in Comparative Example 2 placed against a white background. Detailed Implementation

[0054] The technical solutions of this application will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0055] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the ranges, the endpoint values ​​of the ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. The term "and / or" as used herein is inclusive; for example, "A and / or B" means only A, or only B, or both A and B. The terms "about" and "substantially the same" in this document indicate that reasonable deviations are permissible.

[0056] It should be noted that the performance requirements for alkali-free glass provided in this application, such as optical performance requirements, coefficient of thermal expansion, and Young's modulus, are not limited to a specific thickness. The use of a thickness of approximately 0.5 mm for optical performance testing in the specific embodiment is merely for simplification and is not intended to limit the scope of protection.

[0057] To address the issues of internal bubble defects and reduced transmittance that easily occur during the melting process of alkali-free glass, this application provides an alkali-free glass with a low coefficient of thermal expansion, high transmittance, high strain point, high rigidity, and optical-grade internal quality. The superior properties of this alkali-free glass make it suitable not only for use in magnetic recording media but also in display devices such as OLED displays.

[0058] In some embodiments of this application, an alkali-free glass is provided, wherein the composition of the alkali-free glass, based on the molar percentage of oxides, includes: 67 mol%~71 mol% SiO2, 13 mol%~16 mol% Al2O3, 0.7 mol%~1.2 mol% B2O3, 3 mol%~4 mol% BaO, 4 mol%~7.5 mol% CaO, 4.5 mol%~8 mol% MgO, 0.4 mol%~1 mol% SrO, 0 mol%~0.2 mol% Y2O3+La2O3, and 0.01 mol%~0.2 mol% SnO2;

[0059] The alkali-free glass satisfies the following:

[0060] ,

[0061] Where: η 1650 The viscosity of the alkali-free glass at 1650°C is expressed in poise; η0 is the viscosity constant, with a value of 100 poise; X Al X represents the molar percentage of Al2O3 in the alkali-free glass. B X represents the molar percentage of B2O3 in the alkali-free glass. Mg X represents the molar percentage of MgO in the alkali-free glass. Ca X represents the molar percentage of CaO in the alkali-free glass. Ba X represents the molar percentage of BaO in the alkali-free glass. Sn The molar percentage of SnO2 in the alkali-free glass; α is the effective factor of SnO2 in suppressing bubbles, with a value of 0.8; K Sn is the hindrance constant, with a value of 0.1.

[0062] This application research found that whether bubbles in glass can rise and overflow during the melt refining stage is strongly correlated with the following factors: melt viscosity η and glass composition. For example, when η is too high, bubbles are less likely to rise. Excessive Al2O3 content in the glass composition increases the viscosity of the molten glass and increases bubble retention. Simultaneously, the content of alkaline earth metal oxides such as MgO, CaO, and BaO, as well as B2O3, in the glass composition also affects the fluidity of the molten glass, thus affecting the bubble retention effect. The refining agent SnO2 in the glass composition affects bubble formation and dissolution state by altering oxidizing properties, surface tension, and redox balance. Based on these findings, this application proposes the Bubble Index (BI), i.e. . This application optimizes the glass composition to ensure that each component in the alkali-free glass meets specific content requirements and that the viscosity of the molten glass meets a specific relationship (BI) requirement with respect to its composition. By utilizing the synergistic effect of the components, while ensuring that the prepared alkali-free glass possesses excellent properties such as a low coefficient of thermal expansion, a high strain point, and high rigidity, it significantly improves the problems of internal bubble defects and reduced transmittance during the glass melting process, enabling the obtained alkali-free glass to meet optical-grade internal quality and high transmittance. Preferably, controlling the BI within the range specified in this application is beneficial for obtaining alkali-free glass with good overall uniformity and a satisfactory internal bubble level. Specifically, when BI < 1.5, bubbles are prone to rapid collapse, which greatly increases the risk of coloration in the glass product and reduces its transmittance; while when BI > 3.7, bubbles are difficult to expel, which is detrimental to obtaining optical-grade internal quality.

[0063] In this application, the SiO2 content in alkali-free glass affects the glass structure stability, coefficient of thermal expansion and mechanical properties. In order to obtain a lower coefficient of thermal expansion, a higher Young's modulus and better chemical stability, the SiO2 content in alkali-free glass is 67 mol% to 71 mol%, preferably 67.12 mol% to 70.36 mol%.

[0064] In some embodiments of this application, the SiO2 content in the alkali-free glass, based on the molar percentage of oxides, can be 67 mol%, 67.12 mol%, 67.19 mol%, 67.55 mol%, 67.80 mol%, 67.92 mol%, 67.95 mol%, 68 mol%, 68.12 mol%, 68.69 mol%, 68.81 mol%, 68.88 mol%, 68.9 mol%, 69 mol%, 69.04 mol%, 69.10 mol%, 69.28 mol%, 69.43 mol%, 69.48 mol%, 69.48 mol%, 69.50 mol%, 69.57 mol%, 69.62 mol%, 69.63 mol%, 69.79 mol%, 69.9 mol%, 70 mol%. The values ​​can be 70.2 mol%, 70.36 mol%, 70.5 mol%, 70.8 mol%, or 71 mol%, or any value within a range defined by any two of the above specific values ​​as endpoints, as long as the desired performance of the alkali-free glass or glass product is obtained. It should be understood that, in specific embodiments, any of the above ranges can be combined with any other range, as long as the desired performance of the alkali-free glass or glass product is obtained.

[0065] In this application, the Al2O3 content in the alkali-free glass affects the glass melting temperature, softening temperature, viscosity, and mechanical properties. In order for the glass to be meltable at 1650°C and have a softening temperature higher than 1025°C, and to have a high Young's modulus, the Al2O3 content in the alkali-free glass is 13 mol% to 16 mol%, preferably 13.5 mol% to 15.5 mol%, and more preferably 13.76 mol% to 15.33 mol%.

[0066] In some embodiments of this application, the content of Al2O3 in the composition of alkali-free glass, based on the molar percentage of oxides, can be 13 mol%, 13.2 mol%, 13.5 mol%, 13.76 mol%, 13.78 mol%, 13.8 mol%, 13.85 mol%, 13.88 mol%, 14 mol%, 14.2 mol%, 14.23 mol%, 14.32 mol%, 14.35 mol%, 14.5 mol%, 14.63 mol%, 14.75 mol%, 14.85 mol%, 14.87 mol%, 14.96 mol%, 15 mol%, 15.13 mol%, 15.33 mol%, 15.5 mol%, or 16 mol, or can be a value within the range of any two of the above specific values ​​as endpoints, as long as the alkali-free glass or glass product with the desired properties of this application can be obtained. It should be understood that, in specific implementation schemes, any of the above ranges can be combined with any other ranges, as long as the alkali-free glass or glass product with the properties required by this application can be obtained.

[0067] In this application, the content of B2O3 in alkali-free glass affects the melting temperature and mechanical strength. In order to achieve fluxing without affecting the mechanical properties of the glass, the content of B2O3 in alkali-free glass is 0.7 mol% to 1.2 mol%, preferably 0.71 mol% to 1.13 mol%.

[0068] In some embodiments of this application, the content of B2O3 in the composition of alkali-free glass, based on the molar percentage of oxides, can be 0.7 mol%, 0.71 mol%, 0.72 mol%, 0.73 mol%, 0.75 mol%, 0.79 mol%, 0.8 mol%, 0.85 mol%, 0.87 mol%, 0.88 mol%, 0.9 mol%, 0.94 mol%, 0.98 mol%, 1 mol%, 1.06 mol%, 1.1 mol%, 1.11 mol%, 1.13 mol%, or 1.2 mol%, or a value within a range defined by any two of the above specific values ​​as endpoints, as long as the alkali-free glass or glass product with the desired performance of this application is obtained. It should be understood that in specific embodiments, any of the above ranges can be combined with any other ranges, as long as the alkali-free glass or glass product with the desired performance of this application is obtained.

[0069] In this application, BaO in the alkali-free glass can act as a flux, improving the chemical stability of the glass; however, excessive content can easily lead to a decrease in mechanical properties. The BaO content in the alkali-free glass of this application is 3 mol% to 4 mol%, preferably 3.14 mol% to 4.0 mol%.

[0070] In some embodiments of this application, the BaO content in the alkali-free glass, based on the molar percentage of oxides, can be 3 mol%, 3.14 mol%, 3.16 mol%, 3.2 mol%, 3.22 mol%, 3.35 mol%, 3.4 mol%, 3.44 mol%, 3.46 mol%, 3.51 mol%, 3.55 mol%, 3.6 mol%, 3.64 mol%, 3.67 mol%, 3.76 mol%, 3.8 mol%, 3.81 mol%, 3.84 mol%, 3.86 mol%, 3.88 mol%, 3.92 mol%, or 4 mol%, or a value within a range defined by any two of the above specific values ​​as endpoints, as long as the alkali-free glass or glass product with the desired performance of this application is obtained. It should be understood that in specific embodiments, any of the above ranges can be combined with any other ranges, as long as the alkali-free glass or glass product with the desired performance of this application is obtained.

[0071] In this application, CaO in the alkali-free glass can aid melting and increase the Young's modulus of the glass; however, excessive CaO content can easily lead to an increase in the coefficient of thermal expansion of the glass. The CaO content in the alkali-free glass of this application is 4 mol% to 7.5 mol%, preferably 4.35 mol% to 7.35 mol%.

[0072] In some embodiments of this application, the CaO content in the alkali-free glass, based on the molar percentage of oxides, can be 4 mol%, 4.35 mol%, 4.5 mol%, 4.56 mol%, 5 mol%, 5.12 mol%, 5.24 mol%, 5.31 mol%, 5.32 mol%, 5.47 mol%, 5.5 mol%, 5.56 mol%, 5.86 mol%, 6 mol%, 6.01 mol%, 6.19 mol%, 6.23 mol%, 6.25 mol%, 6.35 mol%, 6.36 mol%, 6.5 mol%, 6.55 mol%, 7 mol%, 7.12 mol%, 7.35 mol%, or 7.5 mol%, or a value within a range defined by any two of the above specific values ​​as endpoints, as long as the alkali-free glass or glass product with the desired performance of this application is obtained. It should be understood that in specific embodiments, any of the above ranges can be combined with any other ranges, as long as the alkali-free glass or glass product with the desired performance of this application is obtained.

[0073] In this application, MgO in alkali-free glass can help the glass melt at high temperatures, and can also reduce the coefficient of thermal expansion and increase Young's modulus. However, if its content is not appropriate, it can easily lead to increased viscosity at low temperatures, which will affect glass forming. The MgO content in the alkali-free glass of this application is 4.5 mol% to 8 mol%, preferably 4.87 mol% to 7.55 mol%.

[0074] In some embodiments of this application, the MgO content in the alkali-free glass, based on the molar percentage of oxides, can be 4.5 mol%, 4.87 mol%, 4.98 mol%, 5 mol%, 5.02 mol%, 5.03 mol%, 5.06 mol%, 5.13 mol%, 5.22 mol%, 5.5 mol%, 5.53 mol%, 5.86 mol%, 5.88 mol%, 6 mol%, 6.01 mol%, 6.02 mol%, 6.1 mol%, 6.12 mol%, 6.3 mol%, 6.5 mol%, 6.8 mol%, 7 mol%, 7.12 mol%, 7.23 mol%, 7.5 mol%, 7.55 mol%, 7.8 mol%, or 8 mol%, or a value within a range defined by any two of the above specific values ​​as endpoints, as long as the alkali-free glass or glass product with the desired performance of this application is obtained. It should be understood that in specific embodiments, any of the above ranges can be combined with any other ranges, as long as the alkali-free glass or glass product with the desired performance of this application is obtained.

[0075] In this application, SrO in alkali-free glass generally exhibits synergistic effects with other alkaline earth metals, and its content affects the characteristic thermal temperature and displays nonlinear characteristics. This application introduces an appropriate amount of SrO to reduce the coefficient of thermal expansion, increase the characteristic temperature, and reduce the surface tension of the melt. The SrO content in the alkali-free glass of this application is 0.4 mol% to 1 mol%, preferably 0.46 mol% to 0.88 mol%.

[0076] In some embodiments of this application, the SrO content in the alkali-free glass, based on the molar percentage of oxides, can be 0.4 mol%, 0.46 mol%, 0.5 mol%, 0.51 mol%, 0.52 mol%, 0.56 mol%, 0.59 mol%, 0.6 mol%, 0.65 mol%, 0.7 mol%, 0.71 mol%, 0.76 mol%, 0.8 mol%, 0.85 mol%, 0.87 mol%, 0.88 mol%, 0.9 mol%, or 1 mol, or a value within a range defined by any two of the above specific values ​​as endpoints, as long as the alkali-free glass or glass product with the desired performance of this application is obtained. It should be understood that in specific embodiments, any of the above ranges can be combined with any other ranges, as long as the alkali-free glass or glass product with the desired performance of this application is obtained.

[0077] In this application, Y2O3 and La2O3 in alkali-free glass have similar functions. Introducing a small amount of Y2O3 and La2O3 can reduce the high-temperature viscosity of the glass, which is beneficial for the elimination of bubbles. At the same time, Y2O3 and La2O3 can fill the gaps in the glass network. The high ion field strength makes the glass structure compact and increases the Young's modulus. However, if the content is too high, too much non-bridging oxygen will be introduced, which will destroy the network structure and reduce the Young's modulus of the glass. Therefore, the content of Y2O3+La2O3 in the alkali-free glass of this application is 0 mol%~0.2 mol.

[0078] In some embodiments of this application, the content of Y₂O₃ + La₂O₃ in the alkali-free glass, based on the molar percentage of oxides, can be 0 mol%, 0.01 mol%, 0.02 mol%, 0.03 mol%, 0.04 mol%, 0.05 mol%, 0.06 mol%, 0.07 mol%, 0.08 mol%, 0.09 mol%, 0.10 mol%, 0.11 mol%, 0.12 mol%, 0.13 mol%, 0.15 mol%, 0.17 mol%, 0.18 mol%, 0.19 mol%, or 0.2 mol%, or a value within a range defined by any two of the above specific values ​​as endpoints, as long as the alkali-free glass or glass product with the desired performance of this application is obtained. It should be understood that in specific embodiments, any of the above ranges can be combined with any other ranges, as long as the alkali-free glass or glass product with the desired performance of this application is obtained.

[0079] In some embodiments of this application, the content of Y₂O₃ in the alkali-free glass, based on the molar percentage of oxides, can be 0 mol%, 0.01 mol%, 0.02 mol%, 0.03 mol%, 0.04 mol%, 0.05 mol%, 0.06 mol%, 0.07 mol%, 0.08 mol%, 0.09 mol%, 0.10 mol%, 0.11 mol%, 0.12 mol%, 0.13 mol%, 0.15 mol%, 0.17 mol%, 0.18 mol%, 0.19 mol%, or 0.2 mol%, or a value within a range defined by any two of the above specific values ​​as endpoints, as long as the alkali-free glass or glass product with the desired performance of this application is obtained. It should be understood that in specific embodiments, any of the above ranges can be combined with any other ranges, as long as the alkali-free glass or glass product with the desired performance of this application is obtained.

[0080] In some embodiments of this application, the content of La2O3 in the alkali-free glass, based on the molar percentage of oxides, can be 0 mol%, 0.01 mol%, 0.02 mol%, 0.03 mol%, 0.04 mol%, 0.05 mol%, 0.06 mol%, 0.07 mol%, 0.08 mol%, 0.09 mol%, 0.10 mol%, 0.11 mol%, 0.12 mol%, 0.13 mol%, 0.15 mol%, 0.17 mol%, 0.18 mol%, 0.19 mol%, or 0.2 mol%, or a value within a range defined by any two of the above specific values ​​as endpoints, as long as the alkali-free glass or glass product with the desired performance of this application is obtained. It should be understood that in specific embodiments, any of the above ranges can be combined with any other ranges, as long as the alkali-free glass or glass product with the desired performance of this application is obtained.

[0081] In this application, SnO2 is introduced into the alkali-free glass as a clarifying agent to assist in glass clarification and reduce bubbles. However, excessive SnO2 content can easily lead to glass coloration and reduce transmittance. The SnO2 content in the alkali-free glass of this application is 0.01 mol% to 0.2 mol%, preferably 0.08 mol% to 0.2 mol%.

[0082] In some embodiments of this application, the SnO2 content in the alkali-free glass, based on the molar percentage of oxides, can be 0.01 mol%, 0.05 mol%, 0.08 mol%, 0.09 mol%, 0.1 mol%, 0.11 mol%, 0.12 mol%, 0.13 mol%, 0.14 mol%, 0.15 mol%, 0.16 mol%, 0.17 mol%, 0.18 mol%, 0.19 mol%, or 0.2 mol%, or a value within a range defined by any two of the above specific values ​​as endpoints, as long as the alkali-free glass or glass product with the desired performance of this application is obtained. It should be understood that in specific embodiments, any of the above ranges can be combined with any other ranges, as long as the alkali-free glass or glass product with the desired performance of this application is obtained.

[0083] In some embodiments of this application, BI (i.e., The value of ) can be 1.5, 1.7, 1.77, 1.78, 1.98, 2, 2.2, 2.25, 2.26, 2.33, 2.36, 2.43, 2.49, 2.5, 2.53, 2.65, 2.7, 2.72, 2.76, 2.79, 2.88, 2.90, 3, 3.03, 3.04, 3.2, 3.5, 3.51, or 3.7, or it can be a value within a range defined by any two of the above specific values ​​as endpoints, as long as it yields the alkali-free glass or glass product with the performance required by this application. It should be understood that, in specific embodiments, any of the above ranges can be combined with any other range, as long as it yields the alkali-free glass or glass product with the performance required by this application.

[0084] In this application, "alkali-free" means substantially free of alkali metals, that is, in the glass composition, the molar percentage of oxides, Li₂O + Na₂O + K₂O < 0.1 mol%. "Substantially free" means that the compound, molecule, or element was not intentionally added as a raw material to the alkali-free glass or glass product of this application; however, as raw materials and / or equipment for producing alkali-free glass or glass products, there may be certain impurities or components that are not intentionally added, which may be present in small or trace amounts in the final alkali-free glass or glass product, and such situations are also within the scope of protection of this application.

[0085] In some embodiments of this application, the alkali-free glass satisfies:

[0086] ,

[0087] Wherein: T 350P X is the temperature at which the viscosity of the alkali-free glass melt is 350 poise; Sn X represents the molar percentage of SnO2 in the alkali-free glass. Al X represents the molar percentage of Al2O3 in the alkali-free glass. Si The molar percentage of SiO2 in the alkali-free glass is given.

[0088] This study found that high-temperature melting increases the risk of glass coloration, especially when the temperature exceeds 1600°C and the melt is in a weak oxygen atmosphere, which increases the risk of Sn in the glass. 4+ Pt and Rh are easily reduced to Sn in the platinum-rhodium crucible used for melting, while Pt and Rh are oxidized to Pt. 2+ ,Rh 3+ Pt dissolved in the glass 2+ ,Rh 3+Strong absorption of light in the 330-370nm range can cause glass to turn yellowish-brown, and in severe cases, black, directly affecting its transmittance in the visible region. This reaction is also closely related to the Al2O3 and SiO2 content in the glass. Appropriately increasing the Al2O3 and SiO2 content stabilizes the glass network structure, which can suppress the aforementioned reactions to some extent, thus reducing the risk of coloration. Based on these findings, this application proposes a Color Index (CI), namely… Preferably, controlling the transmittance (CI) within the range specified in this application is beneficial for ensuring that the transmittance of the alkali-free glass at a wavelength of 360 nm is ≥90%. For the alkali-free glass involved in this application, the transmittance at a wavelength of 360 nm is its lowest value in the entire visible light band. When the transmittance is ≥90%, it indicates that the transmittance of the glass at any position in the entire visible light band is not less than 90%, and the average transmittance in the visible light range is also greater than or equal to 90%. The transmittance level of alkali-free glass in the visible light band can reflect its coloring during the high-temperature melting process. The higher the transmittance, the more significantly the coloring problem of the glass has been improved; conversely, the lower the transmittance, the more obvious the coloring phenomenon of the glass has occurred. In this application, by adopting an implementation scheme that satisfies the CI relationship, alkali-free glass with better transmittance can be obtained.

[0089] In some embodiments of this application, CI (i.e., The value of ) can be 0.13, 0.27, 0.21, 0.22, 0.28, 0.39, 0.34, 0.4, 0.37, 0.14, 0.41, or 0.42, or it can be a value within a range defined by any two of the above specific values ​​as endpoints, as long as it yields alkali-free glass or glass products with the desired performance of this application. It should be understood that, in specific embodiments, any of the above ranges can be combined with any other range, as long as it yields alkali-free glass or glass products with the desired performance of this application.

[0090] In some embodiments of this application, the composition of the alkali-free glass, based on the molar percentage of oxides, satisfies: 14.5 mol% ≤ MgO + CaO + SrO + BaO ≤ 18.1 mol. In some embodiments, the molar percentage of MgO+CaO+SrO+BaO in the alkali-free glass can be 14.5 mol%, 14.64 mol%, 14.68 mol%, 14.76 mol%, 14.97 mol%, 15 mol%, 15.45 mol%, 15.49 mol%, 15.5 mol%, 15.63 mol%, 15.65 mol%, 15.68 mol%, 15.8 mol%, 15.83 mol%, 15.85 mol%, 16 mol%, 16.23 mol%, 16.39 mol%, 16.5 mol%, 16.9 mol%, 17 mol%, 17.2 mol%, 17.5 mol%, 17.8 mol%, 18.06 mol%, or 18.1 mol%, or can be values ​​within a range defined by any two of the above specific values ​​as endpoints, as long as the alkali-free glass or glass product with the desired properties of this application can be obtained. It should be understood that, in specific implementation schemes, any of the above ranges can be combined with any other ranges, as long as the alkali-free glass or glass product with the properties required by this application can be obtained. This application has found that the total content of alkaline earth metal oxides RO [MgO+CaO+SrO+BaO] within the range of this application is beneficial in ensuring that alkali-free glass achieves high mechanical properties and optical-grade internal quality. If the total content of alkaline earth metal oxides RO is too low, it will increase the difficulty of glass melting, resulting in a higher high-temperature viscosity, which easily leads to an increase in defects such as internal bubbles; if the total content of alkaline earth metal oxides RO is too high, it will lead to a higher free oxygen content inside the glass, which easily causes a loose glass network structure, resulting in a decrease in the mechanical properties and thermal stability of the glass.

[0091] In some embodiments of this application, the composition of the alkali-free glass, based on the molar percentage of oxides, satisfies: 0.3 ≤ MgO / (MgO+CaO+SrO+BaO) ≤ 0.5. In some embodiments, the value of MgO / (MgO+CaO+SrO+BaO) in the alkali-free glass, based on the molar percentage of oxides, can be 0.3, 0.317, 0.320, 0.324, 0.330, 0.340, 0.348, 0.349, 0.35, 0.353, 0.367, 0.370, 0.379, 0.385, 0.391, 0.4, 0.41, 0.45, 0.46, 0.456, or 0.5, or a value within a range defined by any two of the above specific values ​​as endpoints, as long as the alkali-free glass or glass product with the desired performance of this application is obtained. It should be understood that, in specific implementations, any of the above ranges can be combined with any other ranges, as long as the desired properties of the alkali-free glass or glass article of this application can be obtained. In this application, Mg 2+ Due to its high electric field strength, MgO exhibits a localized agglomeration effect, strengthening the network structure. Appropriate amounts of MgO help improve the Young's modulus and crystallization properties of the glass. CaO, SrO, and BaO primarily function as fluxing agents and regulate glass properties. Furthermore, the introduction of various alkaline earth metal oxides creates a mixed alkali effect, which benefits both the mechanical strength of the glass and reduces its forming difficulty. This study found that limiting the MgO / (MgO+CaO+SrO+BaO) ratio within a specific range improves the glass's crystallization properties and lowers its liquidus temperature. If the MgO / (MgO+CaO+SrO+BaO) ratio is too low, the improvement in crystallization properties is not significant, and the liquidus temperature tends to be too high, increasing forming difficulty. If the MgO / (MgO+CaO+SrO+BaO) ratio is too high, the improvement in fluxing effect is not significant, the glass melting temperature tends to increase, and the strong agglomeration effect of MgO also tends to lead to a higher liquidus temperature.

[0092] In some embodiments of this application, the composition of the alkali-free glass, based on the molar percentage of oxides, satisfies the following condition: 1.8 ≤ 10 × Al₂O₃ / SiO₂ ≤ 2.3. In some embodiments, the value of 10 × Al₂O₃ / SiO₂ in the alkali-free glass, based on the molar percentage of oxides, can be 1.8, 1.85, 1.9, 1.97, 1.98, 1.99, 2, 2.04, 2.05, 2.06, 2.07, 2.08, 2.09, 2.1, 2.14, 2.15, 2.2, 2.22, or 2.3, or a value within a range defined by any two of the above specific values ​​as endpoints, as long as the alkali-free glass or glass product with the desired performance of this application is obtained. It should be understood that in specific embodiments, any of the above ranges can be combined with any other range, as long as the alkali-free glass or glass product with the desired performance of this application is obtained. In this application, Al2O3 serves as a network intermediate, capable of binding free oxygen into the glass network and strengthening its structure. This research found that limiting the 10×Al2O3 / SiO2 ratio to a specific range is beneficial for improving the mechanical properties and thermal stability of the glass. If the 10×Al2O3 / SiO2 value is too high, it increases the glass melting temperature, thereby increasing the risk of glass coloration. Simultaneously, it may lead to the presence of unmelted Al2O3 in the glass, reducing its internal quality and increasing the risk of crystallization. Conversely, if the 10×Al2O3 / SiO2 value is too low, the glass network structure is not dense enough, easily leading to a decrease in thermal stability, and the mechanical properties may not achieve the expected results.

[0093] In some embodiments of this application, the composition of the alkali-free glass, based on the molar percentage of oxides, satisfies: 0.95 ≤ (MgO + CaO + SrO + BaO) / Al2O3 ≤ 1.32. In some embodiments, the value of (MgO + CaO + SrO + BaO) / Al2O3 in the alkali-free glass, based on the molar percentage of oxides, can be 0.95, 0.98, 0.99, 1, 1.01, 1.04, 1.05, 1.1, 1.11, 1.12, 1.13, 1.14, 1.15, 1.2, 1.22, 1.25, 1.3, 1.31, or 1.32, or a value within a range defined by any two of the above specific values ​​as endpoints, as long as the alkali-free glass or glass product with the desired performance of this application is obtained. It should be understood that in specific embodiments, any of the above ranges can be combined with any other ranges, as long as the alkali-free glass or glass product with the desired performance of this application is obtained. This study found that limiting the (MgO+CaO+SrO+BaO) / Al2O3 ratio to a specific range is beneficial for obtaining glass products with excellent quality and performance. If the value of (MgO+CaO+SrO+BaO) / Al2O3 is too low, it will increase the difficulty of melting, increase the viscosity of the molten glass, and affect the internal bubble removal effect; if the value of (MgO+CaO+SrO+BaO) / Al2O3 is too high, it will easily lead to a decrease in the mechanical properties and thermal stability of the glass.

[0094] In some embodiments of this application, the composition of the alkali-free glass, based on the molar percentage of oxides, satisfies: 5.1 ≤ 100 × B₂O₃ / Al₂O₃ ≤ 7.8. In some embodiments, the value of 100 × B₂O₃ / Al₂O₃ in the alkali-free glass, based on the molar percentage of oxides, can be 5.1, 5.20, 5.27, 5.30, 5.36, 5.5, 5.68, 5.8, 5.81, 5.94, 5.95, 6, 6.13, 6.21, 6.34, 6.5, 6.90, 7, 7.45, 7.47, 7.5, 7.64, 7.70, or 7.8, or a value within a range defined by any two of the above specific values ​​as endpoints, as long as the alkali-free glass or glass product with the desired performance of this application is obtained. It should be understood that, in specific implementation schemes, any of the above ranges can be combined with any other ranges, as long as the alkali-free glass or glass product with the desired properties of this application can be obtained. In this application, B2O3 has a good fluxing effect and is beneficial for reducing the coefficient of thermal expansion of glass. This application has found that limiting 100×B2O3 / Al2O3 within a specific range can enable the glass network structure to achieve a better chemical state and ratio, which is beneficial for achieving low melting temperature, high resistance to crystallization, excellent thermal stability and mechanical strength of glass under industrially feasible process conditions. If the value of 100×B2O3 / Al2O3 is too low, the fluxing effect of B2O3 is not obvious, which can easily lead to an increase in the melting temperature of the glass, thereby increasing the risk of coloration of the glass; if the value of 100×B2O3 / Al2O3 is too high, the thermal stability and Young's modulus of the glass may not achieve the expected results.

[0095] In some embodiments of this application, the composition of the alkali-free glass, based on the molar percentage of oxides, satisfies the following: SiO2 67.12 mol%~70.36 mol%; and / or, Al2O3 13.5 mol%~15.5 mol%, preferably 13.76 mol%~15.33 mol%; and / or, B2O3 0.71 mol%~1.13 mol%; and / or, BaO 3.14 mol%~4.0 mol%; and / or, CaO 4.35 mol%~7.35 mol%; and / or, MgO 4.87 mol%~7.55 mol%; and / or, SrO 0.46 mol%~0.88 mol%; and / or, SnO2 0.08 mol%~0.2 mol%.

[0096] In some embodiments of this application, the composition of the alkali-free glass, based on the molar percentage of oxides, includes: 67.19 mol%~67.92 mol% SiO2, 13.78 mol%~13.88 mol% Al2O3, 0.8 mol%~1.06 mol% B2O3, 3.2 mol%~3.92 mol% BaO, 6.25 mol%~7.12 mol% CaO, 5.88 mol%~7.23 mol% MgO, 0.51 mol%~0.85 mol% SrO, and 0.04 mol%~0.08 mol% Y2O3+La2O. 3、 0.13 mol%~0.16 mol% SnO2; and the alkali-free glass satisfies:

[0097] . This application research found that, by adopting this implementation method, while ensuring that excellent characteristics such as low coefficient of thermal expansion, high strain point, and high rigidity are met, it is beneficial to obtain alkali-free glass with fewer bubble defects and higher transmittance.

[0098] In some embodiments of this application, the alkali-free glass satisfies:

[0099] ,

[0100] Wherein: T 350P X is the temperature at which the viscosity of the alkali-free glass melt is 350 poise. Sn X represents the molar percentage of SnO2 in the alkali-free glass. Al X represents the molar percentage of Al2O3 in the alkali-free glass. Si The molar percentage of SiO2 in the alkali-free glass; and / or, in terms of the molar percentage of oxides, the composition of the alkali-free glass satisfies: 16.9 mol% ≤ MgO + CaO + SrO + BaO ≤ 18.1 mol%; and / or, in terms of the molar percentage of oxides, the composition of the alkali-free glass satisfies: 0.32 ≤ MgO / (MgO + CaO + SrO + BaO) ≤ 0.41; and / or, in terms of the molar percentage of oxides, the composition of the alkali-free glass satisfies: 2 ≤ 10 × Al2O3 / SiO2 ≤ 2.1; and / or, in terms of the molar percentage of oxides, the composition of the alkali-free glass satisfies: 1.2 ≤ (MgO + CaO + SrO + BaO) / Al2O3 ≤ 1.32; and / or, in terms of the molar percentage of oxides, the composition of the alkali-free glass satisfies: 5.8 ≤ 100 × B2O3 / Al2O3 ≤ 7.7.

[0101] In some embodiments of this application, the composition of the alkali-free glass, based on the molar percentage of oxides, includes: 67.55 mol%~69.79 mol% SiO2, 13.76 mol%~15.13 mol% Al2O3, 0.72 mol%~1.11 mol% B2O3, 3.16 mol%~3.88 mol% BaO, 4.56 mol%~6.55 mol% CaO, 4.98 mol%~7.12 mol% MgO, 0.46 mol%~0.87 mol% SrO, and 0 mol%~0.17 mol% Y2O3 + La2O. 3、 0.1 mol%~0.14 mol% SnO2; and the alkali-free glass satisfies:

[0102] . This application research found that adopting this implementation method is beneficial for obtaining alkali-free glass with a higher strain point, lower coefficient of thermal expansion, and higher modulus.

[0103] In some embodiments of this application, the alkali-free glass satisfies:

[0104] ,

[0105] Wherein: T 350P X is the temperature at which the viscosity of the alkali-free glass melt is 350 poise. Sn X represents the molar percentage of SnO2 in the alkali-free glass. Al X represents the molar percentage of Al2O3 in the alkali-free glass. Si The molar percentage of SiO2 in the alkali-free glass; and / or, in terms of the molar percentage of oxides, the composition of the alkali-free glass satisfies: 14.5 mol% ≤ MgO + CaO + SrO + BaO ≤ 16.5 mol%; and / or, in terms of the molar percentage of oxides, the composition of the alkali-free glass satisfies: 0.3 ≤ MgO / (MgO + CaO + SrO + BaO) ≤ 0.46; and / or, in terms of the molar percentage of oxides, the composition of the alkali-free glass satisfies: 1.9 ≤ 10 × Al2O3 / SiO2 ≤ 2.3; and / or, in terms of the molar percentage of oxides, the composition of the alkali-free glass satisfies: 0.95 ≤ (MgO + CaO + SrO + BaO) / Al2O3 ≤ 1.2; and / or, in terms of the molar percentage of oxides, the composition of the alkali-free glass satisfies: 5.1 ≤ 100 × B2O3 / Al2O3 ≤ 7.7.

[0106] In some embodiments of this application, the alkali-free glass satisfies:

[0107] ; and / or,

[0108] The alkali-free glass satisfies the following:

[0109] .

[0110] In some embodiments of this application, the alkali-free glass satisfies:

[0111] .

[0112] In some embodiments of this application, the composition of the alkali-free glass, in terms of the molar percentage of oxides, is as follows:

[0113] The molar percentages of SiO2 are 68.69 mol%, 67.92 mol%, 69.43 mol%, 69.50 mol%, 69.63 mol%, 69.28 mol%, 69.79 mol%, 67.55 mol%, 68.46 mol%, 67.95 mol%, 69.45 mol%, 67.19 mol%, 68.9 mol%, 68.69 mol%, 69.04 mol%, 69.48 mol%, or 69.57 mol%; and / or,

[0114] The molar percentages of Al₂O₃ are 14.75 mol%, 13.88 mol%, 13.76 mol%, 14.63 mol%, 14.23 mol%, 14.96 mol%, 13.78 mol%, 14.85 mol%, 14.2 mol%, 15.13 mol%, 13.85 mol%, 14.32 mol%, or 14.35 mol%; and / or,

[0115] The molar percentages of B₂O₃ are 0.79 mol%, 1.06 mol%, 0.87 mol%, 0.85 mol%, 0.73 mol%, 1.11 mol%, 0.98 mol%, 0.94 mol%, 0.72 mol%, 0.8 mol%, 0.88 mol%, or 0.75 mol%; and / or,

[0116] The molar percentages of BaO are 3.35 mol%, 3.92 mol%, 3.55 mol%, 3.86 mol%, 3.84 mol%, 3.51 mol%, 3.81 mol%, 3.46 mol%, 3.16 mol%, 3.64 mol%, 3.22 mol%, 3.2 mol%, 3.67 mol%, 3.88 mol%, 3.76 mol%, or 3.44 mol%; and / or,

[0117] The molar percentage of CaO is 6.36 mol%, 6.25 mol%, 5.47 mol%, 5.12 mol%, 5.31 mol%, 5.56 mol%, 5.32 mol%, 6.35 mol%, 5.86 mol%, 6.01 mol%, 7.12 mol%, 6.55 mol%, 6.23 mol%, 6.19 mol%, or 4.56 mol%; and / or,

[0118] The molar percentages of MgO are 5.02 mol%, 5.88 mol%, 6.12 mol%, 5.13 mol%, 5.22 mol%, 4.98 mol%, 5.86 mol%, 6.02 mol%, 6.01 mol%, 5.53 mol%, 6.1 mol%, 7.23 mol%, 5.06 mol%, 5.03 mol%, or 7.12 mol%; and / or,

[0119] The molar percentages of SrO are 0.76 mol%, 0.85 mol%, 0.51 mol%, 0.65 mol%, 0.6 mol%, 0.59 mol%, 0.46 mol%, 0.56 mol%, 0.71 mol%, 0.52 mol%, 0.5 mol%, or 0.87 mol%; and / or,

[0120] The molar percentages of Y₂O₃ + La₂O₃ are 0.19 mol%, 0.08 mol%, 0.12 mol%, 0 mol%, 0.15 mol%, 0.11 mol%, 0.17 mol%, or 0.04 mol%; and / or,

[0121] The alkali-free glass satisfies the following: The values ​​are 3.5, 1.78, 2.72, 2.88, 2.79, 3.03, 2.26, 2.76, 2.36, 2.65, 2.43, 1.98, 2.49, 2.53, or 2.33; and / or,

[0122] The alkali-free glass satisfies the following: The values ​​are 0.27, 0.22, 0.28, 0.39, 0.34, 0.4, 0.37, or 0.14.

[0123] In some embodiments of this application, the strain point of the alkali-free glass is ≥745℃. Preferably, the strain point of the alkali-free glass is 745℃~765℃, and more preferably, the strain point of the alkali-free glass is 755℃~765℃.

[0124] In some embodiments of this application, the softening point of the alkali-free glass is ≥1025℃. Preferably, the softening point of the alkali-free glass is 1025℃~1050℃.

[0125] In some embodiments of this application, the liquidus temperature of the alkali-free glass is ≤1085°C. Preferably, the liquidus temperature of the alkali-free glass is ≤1080°C. More preferably, the liquidus temperature of the alkali-free glass is ≤1070°C.

[0126] In some embodiments of this application, the coefficient of thermal expansion of the alkali-free glass is 33 × 10⁻⁶. -7 / ℃~45×10 -7 / ℃. Preferably, the coefficient of thermal expansion of the alkali-free glass is 33×10⁻⁶. -7 / ℃~40×10 -7 / ℃.

[0127] In some embodiments of this application, the alkali-free glass has a Young's modulus ≥ 83 GPa. More preferably, the Young's modulus is 84 GPa to 91 GPa, or 85 GPa to 91 GPa.

[0128] In some embodiments of this application, the alkali-free glass satisfies the following condition: the melt viscosity η of the alkali-free glass at 1650°C is... 1650 ≤200 poises, preferably, η 1650 The viscosity is 150 poise to 200 poise; and / or, the temperature T corresponding to the viscosity of the alkali-free glass melt being 350 poise. 350P ≤1635℃, preferably, T 350P The temperature range is 1600℃ to 1635℃.

[0129] In some embodiments of this application, when the thickness of the alkali-free glass is (0.5±0.01) mm, the transmittance of the alkali-free glass at a wavelength of 360 nm is ≥89%. Preferably, when the thickness of the alkali-free glass is (0.5±0.01) mm, the transmittance of the alkali-free glass at a wavelength of 360 nm is ≥90%. More preferably, when the thickness of the alkali-free glass is (0.5±0.01) mm, the transmittance of the alkali-free glass at a wavelength of 360 nm is ≥91%. More preferably, when the thickness of the alkali-free glass is (0.5±0.01) mm, the transmittance of the alkali-free glass at a wavelength of 360 nm is ≥92%.

[0130] In some embodiments of this application, when the thickness of the alkali-free glass is (0.5±0.01) mm and the surface area of ​​the main surface is (100±1) cm², the alkali-free glass contains no bubbles with a diameter greater than 0.02 mm, and the number of bubbles with a diameter less than or equal to 0.02 mm does not exceed 15. Preferably, when the thickness of the alkali-free glass is (0.5±0.01) mm and the surface area of ​​the main surface is (100±1) cm², the alkali-free glass contains no bubbles with a diameter greater than 0.02 mm, and the number of bubbles with a diameter less than or equal to 0.02 mm does not exceed 10. More preferably, when the thickness of the alkali-free glass is (0.5±0.01) mm and the surface area of ​​the main surface is (100±1) cm², the alkali-free glass contains no bubbles with a diameter greater than 0.02 mm, and the number of bubbles with a diameter less than or equal to 0.02 mm does not exceed 3.

[0131] In this application, the forming method of the alkali-free glass is not limited, as long as it achieves the purpose of this application. For example, forming methods such as the down-drawing method (overflow down-drawing method, slot down-drawing method, re-drawing method, etc.), float glass, overflow, rolling, and casting can be used. For example, the preparation method of the alkali-free glass described in this application may include, but is not limited to, the following steps: according to the molar percentage of oxides, the ingredients are batched according to the composition of the alkali-free glass, mixed evenly, melted, clarified, and formed, and then cooled and annealed to obtain the alkali-free glass.

[0132] In specific embodiments of this application, various forming methods can be used to prepare and form the alkali-free glass, such as the brick melting method and the overflow down-drawing method.

[0133] For example, the alkali-free glass can be prepared and formed by the fused brick method, which may include, but is not limited to, the following steps: the ingredients are prepared according to the composition of the alkali-free glass based on the molar percentage of oxides, mixed evenly, melted into a glass melt, the clarified glass melt is injected into a molding mold, and after the molding is completed, it is transferred to an annealing furnace at an annealing temperature of 785℃~820℃. After annealing, the corresponding glass brick can be obtained.

[0134] Exemplarily, the alkali-free glass can be prepared and formed using an overflow forming method. This overflow forming method may include, but is not limited to, the following steps: ingredients are prepared according to the composition of the alkali-free glass based on the molar percentage of oxides; after uniform mixing, the mixture is melted into a glass melt; the clarified glass melt overflows from both sides of a wedge-shaped trough-like refractory, allowing the overflowing molten glass melt to converge at the lower end of the wedge while maintaining a temperature of 1400℃~1250℃; the forming temperature is then controlled at 1250℃~1100℃ while extending downwards; subsequently, the temperature is slowly reduced from approximately 1100℃ to approximately 650℃ to complete annealing, thereby obtaining the final glass substrate. In the overflow downward drawing method, the surface of the glass substrate does not contact the refractory but is formed in a free surface state; the forming thickness of the alkali-free glass can be 0.3~1.1mm. In some embodiments, the thickness of the alkali-free glass can be 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, or a value within a range of any two of these values.

[0135] This application does not impose any particular restrictions on the melting temperature and time for preparing molten glass, as long as all components are sufficiently melted. Preferably, the melting temperature is 1580℃~1650℃, and the melting time is 8~24 hours.

[0136] In this application, the cooling and forming temperature during the preparation of alkali-free glass is not limited, as long as the purpose of this application can be achieved. Preferably, the cooling and forming temperature can be 1250℃~1100℃.

[0137] In this application, the annealing temperature and time during the preparation of the alkali-free glass are not limited, as long as the purpose of this application can be achieved. Preferably, the annealing temperature can be 785℃~820℃ and the annealing time can be 0.5~10 hours.

[0138] In some embodiments of this application, a glass substrate for magnetic storage media is also provided, which includes the alkali-free glass described in this application.

[0139] In some embodiments of this application, a magnetic storage device is also provided, which includes the alkali-free glass described in this application or a glass substrate including the magnetic storage medium described in this application.

[0140] In some embodiments of this application, a hard disk drive (HDD) is also provided, which includes the alkali-free glass described in this application. The alkali-free glass provided in this application has a low coefficient of thermal expansion, high transmittance, high strain point, high rigidity, and optical-grade internal quality. When applied to HDDs, it can ensure that the HDD has higher storage density and faster read / write speeds.

[0141] In some embodiments of this application, a glass substrate for a display is also provided, comprising the alkali-free glass described in this application. The excellent properties of the alkali-free glass provided in this application make it suitable not only for use in magnetic recording media but also for use in display devices, such as OLED displays.

[0142] In some embodiments of this application, a glass article comprising the alkali-free glass described in this application is also provided.

[0143] Example

[0144] The technical solutions of this application will be further described below with reference to embodiments and comparative examples. The embodiments described in detail below are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0145] Test methods and equipment:

[0146] 1. Strain point: The temperature at which glass begins to exhibit irreversible deformation during heating. It is generally considered the lower limit of glass annealing, corresponding to a viscosity of approximately 10. 14.5 Pas., in this application, the method for testing the strain point of glass is in accordance with ASTM C336 - "Standard Test Method for Determining Annealing Point and Strain Point of Glass by Fiber Elongation".

[0147] 2. Softening point: The softening point of glass refers to the temperature at which glass begins to deform significantly under its own weight, corresponding to a viscosity of approximately 10. 7.6 Pas., The test method is based on ASTM C338 - Standard Test Method for Softening Point of Glass.

[0148] 3. Liquidus Temperature: The liquidus temperature (TL) of glass refers to the highest temperature at which crystals begin to precipitate when the molten glass is cooled, or the lowest temperature at which the crystals completely melt when heated. The test method refers to GB / T 44753—2024 Test Method for Liquidus Temperature of Ultrathin Glass.

[0149] 4. Coefficient of thermal expansion: The test method refers to GB / T 7962.16-2010- "Test methods for colorless optical glass - Part 16: Coefficient of linear expansion, transition temperature and sag temperature". The average linear thermal expansion coefficient is calculated by measuring the length change of the glass sample during the heating process. This application calculates the linear thermal expansion coefficient from 20℃ to 300℃.

[0150] 5. Young's modulus: Young's modulus is a physical quantity that measures the elastic stiffness of a material, that is, the ratio of stress to strain. The test method refers to GB / T 7962.6-2010- "Test methods for colorless optical glass Part 6: Young's modulus, shear modulus and Poisson's ratio".

[0151] 6. High-temperature viscosity: The test method is in accordance with ASTM C965 - Standard procedure for measuring the viscosity of glass above the softening point.

[0152] 7. Transmittance: Transmittance refers to the ratio of the radiant energy projected onto and transmitted through an object to the total radiant energy projected onto the object during the process of incident light flux from the incident surface to the other side. It should be understood that when light of a certain wavelength shines on a glass surface, the light undergoes reflection, absorption, and transmission. The ratio of the intensity of the transmitted portion to the intensity of the incident light is the transmittance. The transmittance result of glass at a wavelength of 360nm refers to the average transmittance measured at 360nm for multiple glass samples ((0.5±0.01) mm thick) from the same batch, with at least 5 samples taken from each batch for testing. The haze meter used in the test was a Konica Minolta CM-3600A spectrophotometer from Japan, with a transmission optical system, a planar refracting grating for beam splitting, a wavelength range of 360nm-740nm, a wavelength spacing of 10nm, and four pulsed xenon lamps as the illumination source. The ambient temperature where the instrument was placed was approximately 24℃, and the air humidity was approximately 40%.

[0153] 8. Bubble Grade: Assessing the amount of bubbles (gas inclusions) inside the glass is an important indicator of the glass melting quality and uniformity. The sample is cut, ground, and polished to a main surface area of ​​approximately 100 cm². 2 For samples with a thickness of (0.5±0.01) mm, under specific lighting conditions (such as dark field illumination), observation was conducted using a magnifying glass or stereomicroscope with a scale, and the bubbles were graded and counted according to their diameter and number:

[0154] Grade I: No bubbles larger than 0.02 mm, and ≤ 3 bubbles smaller than or equal to 0.02 mm;

[0155] Level II: No bubbles larger than 0.02 mm, and 4 to 10 bubbles smaller than or equal to 0.02 mm;

[0156] Level III: No bubbles larger than 0.02 mm, and 11 to 15 bubbles smaller than or equal to 0.02 mm;

[0157] Unacceptable: Bubble diameter greater than 0.02mm, or more than 15 bubbles less than or equal to 0.02mm.

[0158] 9. Density: Density is the mass per unit volume of a substance, usually represented by ρ. The standard method is the Archimedes' principle buoyancy method as required in GB / T5432-2008 "Determination of Density of Glass by Buoyancy".

[0159] Example 1

[0160] According to the formula in Table 1, the raw materials are converted into a glass production formula and mixed thoroughly. The mixture is then transferred to a furnace for melting at a temperature of 1650℃. After melting and clarifying for 20 hours, molten glass is obtained. The molten glass is then poured into a molding die to form glass products with a thickness of 20mm. After that, the glass is transferred to an annealing furnace at a temperature of 785℃~820℃. Finally, the glass products are processed into the size specifications required for various testing standards.

[0161] Examples 2 to 17

[0162] Except for adjusting the corresponding formulas according to Table 1 or Table 2 to produce glass 2 to glass 17 respectively, the rest is the same as in Example 1.

[0163] Comparative Examples 1 to 9

[0164] Except for adjusting the corresponding formulas according to Table 3 to produce glass 18 to glass 26 respectively, the rest is the same as in Example 1.

[0165] The formulation composition and performance test results of each embodiment are shown in Tables 1 and 2, and the formulation composition and performance test results of each comparative example are shown in Table 3.

[0166] It should be understood that, in terms of the molar percentage of oxides, the composition of the glasses prepared in each embodiment and comparative example is substantially the same as the oxide composition in Tables 1 to 3, except for unavoidable impurities totaling no more than 1%.

[0167] Table 1

[0168] Note: .

[0169] Table 2

[0170] Table 3

[0171] As can be seen from the table above and the accompanying drawings, in the alkali-free glass prepared using the embodiments of this application, by optimizing the glass composition, the components in the alkali-free glass meet specific content requirements, and the viscosity of the molten glass and its composition meet specific relationship requirements (BI). This ensures that the prepared alkali-free glass possesses excellent properties such as a low coefficient of thermal expansion, a high strain point, and high rigidity, while significantly improving the problems of internal bubble defects and reduced transmittance during the glass melting process. The resulting alkali-free glass meets optical-grade internal quality and high transmittance. A partial schematic diagram of glass 2 prepared in Example 2 is shown below. Figure 1 As shown, a partial schematic diagram of the glass 17 prepared in Example 17 is as follows. Figure 2As shown, glass 2 and glass 17 have good overall uniformity, no obvious bubble defects inside, and the bubble level meets the requirements.

[0172] In Comparative Examples 1 to 9, the glass composition did not simultaneously meet the content requirements of each oxide in this application, and / or the bubble index BI did not meet the specific range required by this application. Therefore, the alkali-free glass produced could not simultaneously possess low thermal expansion coefficient, high transmittance, high strain point, high rigidity, and optical-grade internal quality. For example, Comparative Example 1 did not meet the bubble index BI range requirements of this application, resulting in glass 18 with numerous internal bubble defects and an unqualified internal bubble grade. Comparative Example 2 did not meet the requirements of this application regarding the molar percentages of SiO2, B2O3, and BaO, and the bubble index BI range. Consequently, glass 19 produced had low transmittance and numerous internal bubble defects, resulting in an unqualified internal bubble grade. Figure 3 It can be seen that glass 19 has poor overall uniformity, many internal bubble defects, and the internal bubble level does not meet the requirements. Figure 4 As shown, the glass brick prepared in Comparative Example 2 clearly exhibited an undesirable color. In Comparative Example 3, although the bubble index BI was within the range of this application, the molar percentages of SiO2 and BaO did not meet the specific content requirements of this application, resulting in low transmittance of the final glass 20. In Comparative Example 4, although the bubble index BI was within the range of this application, the molar percentages of SiO2 and Al2O3 did not meet the specific content requirements of this application, resulting in low transmittance of the final glass 21. In Comparative Example 5, although the bubble index BI was within the range of this application, the molar percentages of B2O3, BaO, and MgO did not meet the specific content requirements of this application, resulting in a low strain point for the final glass 22. In Comparative Example 6, although the bubble index BI was within the range of this application, the molar percentages of CaO and MgO did not meet the specific content requirements of this application, resulting in low transmittance of the final glass 23. In Comparative Example 7, the molar percentages of Al2O3, B2O3, and BaO, as well as the bubble index BI, did not meet the specific requirements of this application. The resulting glass 24 had a lower strain point and an internal bubble level that did not meet the requirements. In Comparative Examples 8 and 9, the molar percentages of Y2O3 + La2O3 did not meet the specific content requirements of this application. The resulting glasses 25 and 26 exhibited significantly reduced Young's modulus.

[0173] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. An alkali-free glass, characterized in that, The composition of the alkali-free glass, based on the molar percentage of oxides, includes: 67 mol%~71 mol% SiO2, 13 mol%~16 mol% Al2O3, 0.7 mol%~1.2 mol% B2O3, 3 mol%~4 mol% BaO, 4 mol%~7.5 mol% CaO, 4.5 mol%~8 mol% MgO, 0.4 mol%~1 mol% SrO, 0 mol%~0.2 mol% Y2O3+La2O3, and 0.01 mol%~0.2 mol% SnO2; The alkali-free glass satisfies the following: ， in: η 1650 The melt viscosity of the alkali-free glass at 1650°C is expressed in poise. η0 is the viscosity constant, with a value of 100 poise; X Al X represents the molar percentage of Al2O3 in the alkali-free glass. B X represents the molar percentage of B2O3 in the alkali-free glass. Mg X represents the molar percentage of MgO in the alkali-free glass. Ca X represents the molar percentage of CaO in the alkali-free glass. Ba X represents the molar percentage of BaO in the alkali-free glass. Sn The molar percentage of SnO2 in the alkali-free glass; α is the effective factor for SnO2 to suppress bubbles, with a value of 0.8; K Sn It is the hindrance constant, with a value of 0.

1.

2. The alkali-free glass according to claim 1, characterized in that, The alkali-free glass satisfies the following: ， in: T 350P The temperature at which the viscosity of the alkali-free glass melt is 350 poise; X Sn The molar percentage of SnO2 in the alkali-free glass; X Al The molar percentage of Al2O3 in the alkali-free glass; X Si The molar percentage of SiO2 in the alkali-free glass is given.

3. The alkali-free glass according to any one of claims 1 to 2, characterized in that, The composition of the alkali-free glass, based on the molar percentage of oxides, satisfies the following conditions: 14.5 mol% ≤ MgO + CaO + SrO + BaO ≤ 18.1 mol%; and / or, 0.3 ≤ MgO / (MgO + CaO + SrO + BaO) ≤ 0.5; and / or, 1.8 ≤ 10 × Al2O3 / SiO2 ≤ 2.3; and / or, 0.95 ≤ (MgO + CaO + SrO + BaO) / Al2O3 ≤ 1.32; and / or, 0 ≤ Y2O3 + La2O3 ≤ 0.19 mol%; and / or, 5.1 ≤ 100 × B2O3 / Al2O3 ≤ 7.

8.

4. The alkali-free glass according to any one of claims 1 to 3, characterized in that, The composition of the alkali-free glass, based on the molar percentage of oxides, satisfies the following: SiO2 content is 67.12 mol%~70.36 mol%; and / or, The Al₂O₃ content is 13.5 mol%~15.5 mol%, preferably 13.76 mol%~15.33 mol%; and / or, B2O3 content ranges from 0.71 mol% to 1.13 mol%; and / or, BaO content is 3.14 mol%~4.0 mol%; and / or, CaO content is 4.35 mol%~7.35 mol%; and / or, MgO content is 4.87 mol%–7.55 mol%; and / or, SrO is 0.46 mol%~0.88 mol%; and / or, SnO2 content ranges from 0.08 mol% to 0.2 mol%.

5. The alkali-free glass according to claim 1, characterized in that, Based on the molar percentage of oxides, the composition of the alkali-free glass includes: 67.19 mol%~67.92 mol% SiO2, 13.78 mol%~13.88 mol% Al2O3, 0.8 mol%~1.06 mol% B2O3, 3.2 mol%~3.92 mol% BaO, 6.25 mol%~7.12 mol% CaO, 5.88 mol%~7.23 mol% MgO, 0.51 mol%~0.85 mol% SrO, 0.04 mol%~0.08 mol% Y2O3+La2O3, and 0.13 mol%~0.16 mol% SnO2; and the alkali-free glass satisfies: 。 6. The alkali-free glass according to claim 5, characterized in that, The alkali-free glass satisfies the following: ， Wherein: T 350P X is the temperature at which the viscosity of the alkali-free glass melt is 350 poise. Sn X represents the molar percentage of SnO2 in the alkali-free glass. Al X represents the molar percentage of Al2O3 in the alkali-free glass. Si The molar percentage of SiO2 in the alkali-free glass; and / or, The composition of the alkali-free glass, based on the molar percentage of oxides, satisfies: 16.9 mol% ≤ MgO + CaO + SrO + BaO ≤ 18.1 mol%; and / or, The composition of the alkali-free glass, based on the molar percentage of oxides, satisfies: 0.32 ≤ MgO / (MgO+CaO+SrO+BaO) ≤ 0.41; and / or, The composition of the alkali-free glass, based on the molar percentage of oxides, satisfies: 2 ≤ 10 × Al₂O₃ / SiO₂ ≤ 2.1; and / or, The composition of the alkali-free glass, based on the molar percentage of oxides, satisfies: 1.2 ≤ (MgO + CaO + SrO + BaO) / Al₂O₃ ≤ 1.32; and / or, The composition of the alkali-free glass, based on the molar percentage of oxides, satisfies: 5.8 ≤ 100 × B2O3 / Al2O3 ≤ 7.

7.

7. The alkali-free glass according to claim 1, characterized in that, Based on the molar percentage of oxides, the composition of the alkali-free glass includes: 67.55 mol%~69.79 mol% SiO2, 13.76 mol%~15.13 mol% Al2O3, 0.72 mol%~1.11 mol% B2O3, 3.16 mol%~3.88 mol% BaO, 4.56 mol%~6.55 mol% CaO, 4.98 mol%~7.12 mol% MgO, 0.46 mol%~0.87 mol% SrO, 0 mol%~0.17 mol% Y2O3+La2O3, and 0.1 mol%~0.14 mol% SnO2; and the alkali-free glass satisfies: 。 8. The alkali-free glass according to claim 7, characterized in that, The alkali-free glass satisfies the following: ， Wherein: T 350P X is the temperature at which the viscosity of the alkali-free glass melt is 350 poise. Sn X represents the molar percentage of SnO2 in the alkali-free glass. Al X represents the molar percentage of Al2O3 in the alkali-free glass. Si The molar percentage of SiO2 in the alkali-free glass; and / or, The composition of the alkali-free glass, based on the molar percentage of oxides, satisfies: 14.5 mol% ≤ MgO + CaO + SrO + BaO ≤ 16.5 mol%; and / or, The composition of the alkali-free glass, based on the molar percentage of oxides, satisfies: 0.3 ≤ MgO / (MgO+CaO+SrO+BaO) ≤ 0.46; and / or, The composition of the alkali-free glass, based on the molar percentage of oxides, satisfies: 1.9 ≤ 10 × Al₂O₃ / SiO₂ ≤ 2.3; and / or, The composition of the alkali-free glass, based on the molar percentage of oxides, satisfies: 0.95≤(MgO+CaO+SrO+BaO) / Al2O3≤1.2; and / or, based on the molar percentage of oxides, the composition of the alkali-free glass satisfies: 5.1≤100×B2O3 / Al2O3≤7.

7.

9. The alkali-free glass according to claim 2, characterized in that, The alkali-free glass satisfies the following: ; and / or, The alkali-free glass satisfies the following: 。 10. The alkali-free glass according to claim 9, characterized in that, The alkali-free glass satisfies the following: 。 11. The alkali-free glass according to any one of claims 1 to 4, characterized in that, The strain point of the alkali-free glass is ≥745℃, preferably, the strain point of the alkali-free glass is 745℃~765℃, more preferably, the strain point of the alkali-free glass is 755℃~765℃; and / or, The alkali-free glass has a softening point ≥1025℃, preferably, the softening point of the alkali-free glass is 1025℃~1050℃; and / or, The liquidus temperature of the alkali-free glass is ≤1085℃; and / or, The coefficient of thermal expansion of the alkali-free glass is 33 × 10⁻⁶ in the temperature range of 20℃ to 300℃. -7 / ℃ ~45×10 -7 / ℃, preferably, the coefficient of thermal expansion is 33×10⁻⁶℃. -7 / ℃~40×10 -7 / ℃; and / or, The alkali-free glass has a Young's modulus ≥ 83 GPa, preferably 84 GPa to 91 GPa, and more preferably 85 GPa to 91 GPa.

12. The alkali-free glass according to any one of claims 1 to 4, characterized in that, The melt viscosity η of the alkali-free glass at 1650°C 1650 ≤200 poises, preferably, η 1650 For 150 to 200 poises; and / or, The temperature T corresponding to the viscosity of the alkali-free glass melt being 350 poise. 350P ≤1635℃, preferably, T 350P The temperature range is 1600℃ to 1635℃.

13. The alkali-free glass according to any one of claims 1 to 4, characterized in that, When the thickness of the alkali-free glass is (0.5±0.01) mm, the transmittance of the alkali-free glass at a wavelength of 360 nm is ≥89%; preferably, when the thickness of the alkali-free glass is (0.5±0.01) mm, the transmittance of the alkali-free glass at a wavelength of 360 nm is ≥90%; and / or, When the thickness of the alkali-free glass is (0.5±0.01) mm and the surface area of ​​the main surface is (100±1) cm², there are no bubbles with a diameter greater than 0.02 mm in the alkali-free glass, and the number of bubbles with a diameter less than or equal to 0.02 mm does not exceed 15.

14. A glass substrate for magnetic storage media, comprising the alkali-free glass according to any one of claims 1 to 13.

15. A magnetic storage device comprising any one of claims 1 to 13 alkali-free glass or a glass substrate comprising the magnetic storage medium of claim 14.

16. A mechanical hard disk drive comprising the alkali-free glass according to any one of claims 1 to 13.

17. A glass substrate for a display, comprising the alkali-free glass according to any one of claims 1 to 13.

18. A glass article comprising any one of claims 1 to 13.

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