Alkali-free glass, preparation method thereof and magnetic disk substrate glass based on alkali-free glass

Abstract

The invention discloses alkali-free glass, a preparation method thereof and magnetic disk substrate glass based on the alkali-free glass, and the alkali-free glass comprises the following components in percentage by mass: 50%-70% of SiO2, 15%-25% of Al2O3, 0-6% of B2O3, 1-6% of MgO, 0-5% of CaO, 0-4% of SrO, 0-9% of BaO, 0-3% of ZnO, 0-3% of P2O5, 0-5% of Y2O3, 0-3% of La2O3, 0-3% of TiO2 and 0-5% of ZrO2. The chemical durability, mechanical strength, meltability, thermal expansion coefficient, strain point and other physical and chemical properties of the glass are optimized, so that the glass has the advantages of high Young modulus, high strain point, low density and the like, and meets the development trend of magnetic disk glass.

Description

Technical Field

[0001] The present invention belongs to the field of preparation and application of substrate glass, and relates to an alkali-free glass, a preparation method thereof, and a substrate glass for a disk based on the same. Background Art

[0002] With the development of information technology, the demand for data storage has shown an explosive growth, which directly drives a sharp increase in the market demand for high-performance storage media - glass disks. Compared with aluminum substrate disks with poor surface hardness and rigidity, glass disks have good surface hardness and rigidity, low density, low expansion, and high elastic modulus, etc., which meet the performance requirements such as high-density recording and thinning of disks. At the same time, compared with alkali metal-containing glass, the performance of alkali-free glass is better. The lower alkali metal content in alkali-free glass effectively reduces the signal attenuation problem caused by ion migration, thereby improving the stability of data storage and the reading accuracy.

[0003] In the prior art, by introducing a small amount of rare earth metal oxides into the glass, the strain point and elastic modulus of the alkali-free glass are improved, but the introduction of rare earth metal oxides requires a more complex production process and higher technical requirements. It is necessary to precisely control the content and distribution of rare earth elements to ensure that the performance of the glass meets the expectations, which will undoubtedly increase the production cost and manufacturing difficulty. Summary of the Invention

[0004] The purpose of the present invention is to provide an alkali-free glass, a preparation method thereof, and a substrate glass for a disk based on the same, so as to solve the problems of large manufacturing difficulty and high production cost in the prior art.

[0005] To achieve the above object, the present invention adopts the following technical solutions: An alkali-free glass, by mass percentage, includes 50% - 70% of SiO2, 15% - 25% of Al2O3, 0 - 6% of B2O3, 1 - 6% of MgO, 0 - 5% of CaO, 0 - 4% of SrO, 0 - 9% of BaO, 0 - 3% of ZnO, 0 - 3% of P2O5, 0 - 5% of Y2O3, 0 - 3% of La2O3, 0 - 3% of TiO2, and 0 - 5% of ZrO2.

[0006] Furthermore, it further includes a clarifying agent, the clarifying agent includes 0 - 0.5% of SnO2 and / or 0 - 0.6% of CeO2, and the mass percentage of SnO2 + CeO2 is 0 - 0.7%.

[0007] Furthermore, the mass percentage of SiO2 + Al2O3 is 70% - 85%; The mass percentage of SiO2 + Al2O3 + B2O3 is 71.5% - 88.85%; The mass percentage of P2O5 + ZrO2 + TiO2 is 0 to 4.4%; The mass percentage of Y2O3 + La2O3 is 0 to 5.5%.

[0008] Furthermore, the Young's modulus of the non-alkali glass is 80 GPa or more, and the density is less than 2.80 g / cm 3 .

[0009] Furthermore, the strain point of the non-alkali glass is 680 °C or more, and the thermal expansion coefficient is 35×10 -7 ~50×10 -7 / °C.

[0010] A preparation method of the non-alkali glass includes: Mix SiO2, Al2O3, B2O3, MgO, CaO, SrO, BaO, ZnO, P2O5, Y2O3, La2O3, TiO2, ZrO2 and a fining agent evenly, heat and melt, cool and form, cool, and anneal to obtain the non-alkali glass.

[0011] Furthermore, the forming methods include the overflow down-drawing method and the casting method.

[0012] Furthermore, the temperature of the heating and melting is 1550 to 1750 °C, and the heating and melting time is 1 to 12 h.

[0013] Furthermore, the annealing temperature is 600 to 800 °C, and the annealing time is 2 to 8 h.

[0014] A substrate glass for a disk is made of the non-alkali glass described above.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides an alkali-free glass which, by mass percentage, comprises 50% - 70% of SiO2, 15% - 25% of Al2O3, 0 - 6% of B2O3, 1 - 6% of MgO, 0 - 5% of CaO, 0 - 4% of SrO, 0 - 9% of BaO, 0 - 3% of ZnO, 0 - 3% of P2O5, 0 - 5% of Y2O3, 0 - 3% of La2O3, 0 - 3% of TiO2, 0 - 5% of ZrO2 and a fining agent. In the present invention, SiO2 is used as the main component constituting the glass skeleton to improve the chemical durability and mechanical strength of the glass; Al2O3 is beneficial to increasing the elastic modulus of the glass and reducing the crystallization tendency of the glass; B2O3 is used as a flux to reduce the melting temperature of the glass; MgO is beneficial to reducing the high-temperature viscosity, increasing the thermal expansion coefficient and Young's modulus; CaO is used to improve the meltability, increase the thermal expansion coefficient and Young's modulus; SrO can increase the thermal expansion coefficient and Young's modulus and inhibit phase separation; BaO is used to increase the thermal expansion coefficient and durability; ZnO can improve the meltability, reduce the high-temperature viscosity, increase the chemical corrosion resistance and reduce the thermal expansion coefficient; P2O5 is used to increase the strain point and reduce the liquidus temperature of the glass; Y2O3 is used to improve the mechanical properties of the glass; La2O3 can improve the mechanical properties of the glass, increase the chemical stability, reduce the thermal expansion coefficient and improve the processing performance; TiO2 is used to reduce the high-temperature viscosity and improve the meltability; ZrO2 is used to increase the chemical durability; introducing a small amount of fining agent can reduce the bubbles in the alkali-free glass, utilize the fining gas and increase the discharge rate of the bubbles. By precisely controlling the contents of these oxides, the present invention manufactures an alkali-free glass by forming methods such as the overflow down-draw method and casting, optimizing the chemical durability, mechanical strength, meltability, thermal expansion coefficient, strain point and other physical and chemical properties of the glass, making it have the advantages of high Young's modulus, high strain point, low density, etc., and meeting the development trend of disk glass. At the same time, the component and forming method of the alkali-free glass of the present invention follow the concept of environmental friendliness, without any toxic and harmful substances or components, thus meeting the application requirements of different application fields.

[0016] Further, the present invention uses 0 - 0.5% of SnO2 and / or 0 - 0.6% of CeO2 as the fining agent, which can decompose and release oxygen at the melting temperature of the glass, helping to reduce the bubble content in the glass liquid, thereby improving the fining effect of the glass. Detailed implementation manners

[0017] To enable those skilled in the art to understand the features and effects of the present invention, the following provides a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meanings understood by those skilled in the art for the present invention. In case of conflict, the definitions in this specification shall prevail.

[0018] The theories or mechanisms described and disclosed herein, whether right or wrong, shall not in any way limit the scope of the present invention, that is, the content of the present invention can be implemented without being limited by any specific theory or mechanism.

[0019] In this document, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are only for the sake of brevity and convenience. Accordingly, the description of a numerical range or percentage range should be regarded as having covered and specifically disclosed all possible sub-ranges and individual values within the range (including integers and fractions).

[0020] In this document, unless otherwise specified, terms such as "comprising", "including", "containing", "having", or similar terms cover the meanings of "consisting of" and "consisting essentially of". For example, "A comprises a" covers the meanings of "A comprises a and others" and "A consists only of a".

[0021] In this document, for the sake of brevity, all possible combinations of all technical features in each embodiment or example are not described. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as falling within the scope described in this specification.

[0022] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0023] Conventional instruments and equipment in the art are used in the following embodiments. For the experimental methods without specific conditions indicated in the following embodiments, they are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer. Various raw materials are used in the following embodiments. Unless otherwise stated, commercially available products are used, and their specifications are conventional specifications in the art. In the specification of the present invention and the following embodiments, unless otherwise specified, "%" represents weight percentage, "parts" represents weight parts, and the ratio represents weight ratio.

[0024] The present invention will be further described in detail below: The present invention provides an alkali-free glass, which, by mass percentage, comprises 50% - 70% of SiO2, 15% - 25% of Al2O3, 0 - 6% of B2O3, 1 - 6% of MgO, 0 - 5% of CaO, 0 - 4% of SrO, 0 - 9% of BaO, 0 - 3% of ZnO, 0 - 3% of P2O5, 0 - 5% of Y2O3, 0 - 3% of La2O3, 0 - 3% of TiO2, 0 - 5% of ZrO2, and fining agent oxides: 0 - 0.5% of SnO2 and / or 0 - 0.6% of CeO2.

[0025] Among them, the mass percentage of SiO2 + Al2O3 is 70% - 85%; The mass percentage of SiO2 + Al2O3 + B2O3 is 71.5% - 88.85%; The mass percentage of P2O5 + ZrO2 + TiO2 is 0 - 4.4%; The mass percentage of SnO2 + CeO2 is 0 - 0.7%; The mass percentage of Y2O3 + La2O3 is 0 - 5.5%.

[0026] SiO2 is an essential component for forming the glass skeleton. The higher its content, the more it can improve the chemical durability of the glass and the mechanical strength of the glass. Since SiO2 has a tendency to increase the viscosity of the glass melt, if the content is too high, the glass melting temperature is high, it is difficult to melt the sample, it is not easy to form, and it is difficult to obtain a glass with a long working range. Therefore, the upper limit of the SiO2 content is preferably 75%; when the SiO2 content is less, the crystals are likely to become coarser, which will affect the haze of the glass-ceramics and the performance of the glass-ceramics products. Therefore, the lower limit of the SiO2 content is preferably 50%. Therefore, the SiO2 content is 50 - 70%, further 50 - 65%, and still further 55 - 60%.

[0027] Al2O3 is an intermediate oxide and a component for forming the glass network structure. It can greatly improve the chemical stability of the glass, reduce the crystallization tendency of the glass, and also improve the mechanical properties of the glass. Al2O3 has the highest unit volume dissociation energy and a relatively high packing density. Therefore, increasing its content is beneficial to improving the elastic modulus of the glass. When the Al2O3 content is relatively high, the viscosity of the glass melt increases, and the meltability and devitrification resistance decrease. Therefore, the upper limit of the Al2O3 content is 20%; when the Al2O3 content is insufficient, the stability of the glass decreases. Therefore, the lower limit of the Al2O3 content is 15%. Therefore, the Al2O3 content is 15 - 25%, further 17 - 22%, and still further 19 - 22%.

[0028] B2O3, as a flux, can reduce the melting temperature of the glass and help to provide a glass with a low melting temperature. Generally, the amount of boron should be controlled to maintain the chemical durability and mechanical strength of the base glass. When its content is high, the chemical stability of the glass decreases. Therefore, the upper limit of the B2O3 content is 6%. Thus, the B2O3 content is 0 - 6%, further 0 - 4%, and even further 0 - 2.5%.

[0029] MgO is a component that helps to reduce the high - temperature viscosity, increase the thermal expansion coefficient and Young's modulus. Too little MgO content causes a decrease in the glass meltability and Young's modulus; too much MgO content causes a decrease in the glass devitrification resistance and strain point. Therefore, the upper limit of the MgO content is 6%. Thus, the MgO content is 1 - 6%, further 1 - 5%, and even further 1 - 3%.

[0030] CaO is a basic component that helps to improve the meltability and increase the thermal expansion coefficient and Young's modulus. Therefore, the upper limit of the CaO content is 5%. Thus, the CaO content is 0 - 5%, further 1.5 - 5%, and even further 3 - 5%.

[0031] SrO is a component that helps to increase the thermal expansion coefficient and Young's modulus and inhibits phase separation. However, too high a content causes an increase in the specific gravity. Therefore, the upper limit of the SrO content is 4%. Thus, the SrO content is 0 - 4%, further 0 - 3%, and even further 1.5 - 2.5%.

[0032] BaO is a basic component that helps to increase the thermal expansion coefficient and durability. However, too high a content causes an increase in the specific gravity and a decrease in the meltability. Therefore, the upper limit of the BaO content is 9%. Thus, the BaO content is 0 - 9%, further 4 - 9%, and even further 5.5 - 9%.

[0033] ZnO is a component that improves the meltability, can reduce the high - temperature viscosity of the glass, increase the chemical corrosion resistance of the glass, and reduce the thermal expansion coefficient of the glass. However, too much content makes the glass prone to devitrification and the strain point decreases. Therefore, the upper limit of the ZnO content is 3%. Thus, the ZnO content is 0 - 3%, further 0 - 2%, and even further 0 - 1%.

[0034] P2O5 is a component that increases the strain point and reduces the liquidus temperature of the glass. However, too much content causes phase separation in the glass. Therefore, the upper limit of the P2O5 content is 3%. Thus, the P2O5 content is 0 - 3%, further 0 - 2%, and even further 0 - 1%.

[0035] Y2O3 is a component that improves the mechanical properties of the glass. However, as the Y2O3 content increases, the forming temperature of the glass first decreases and then increases. Therefore, the upper limit of the Y2O3 content is 5%. Thus, the Y2O3 content is 0 - 5%, further 1 - 5%, and even further 2 - 5%.

[0036] La2O3 is a component that improves the mechanical properties of glass. Adding a small amount can appropriately improve the chemical stability of the glass, reduce the thermal expansion coefficient, and improve the processing performance of the glass. Therefore, the upper limit of the La2O3 content is 3%. Thus, the La2O3 content is 0 - 3%, further 0 - 2%, and even further 0 - 1%.

[0037] TiO2 is a component that reduces the high - temperature viscosity and improves the fusibility. However, if the content is too high, the glass will be colored and the transmittance of the glass will be reduced. Therefore, the upper limit of the TiO2 content is 3%. Thus, the TiO2 content is 0 - 3%, further 0 - 2.5%, and even further 0 - 1%.

[0038] ZrO2 is a component that improves chemical durability. However, if the content is too high, the glass is prone to devitrification of ZrSiO4. Therefore, the upper limit of the ZrO2 content is 5%. Thus, the ZrO2 content is 0 - 5%, further 0 - 3%, and even further 0 - 1%.

[0039] SnO2 and CeO2 are added as fining agents, which can eliminate the bubbles in the glass melt. Therefore, the SnO2 content is 0 - 0.5% and the CeO2 content is 0 - 0.6%.

[0040] The present invention also provides a method for preparing an alkali - free glass, which specifically includes the following steps: Weigh the weights of SiO2, Al2O3, B2O3, MgO, CaO, SrO, BaO, ZnO, P2O5, Y2O3, La2O3, TiO2, ZrO2 and the fining agent according to the weight ratio of the oxides, pour them into a mixer and mix evenly. Then place them in a platinum or quartz crucible, and melt them in a sample melting furnace at a temperature of 1550 - 1750°C for 1 - 12 h. At the same time, stir during the melting process. After cooling to an appropriate temperature, cast it in a cube mold or form it by the overflow - down - draw method. After cooling to 600 - 800°C, put it into an annealing furnace for annealing treatment for 2 - 8 h to obtain the alkali - free glass.

[0041] The method for preparing the alkali - free glass of the present invention has no special limitation on the cold - processing method. It can adopt the method of natural cooling to room temperature or the method of programmed cooling. The preparation method of the present invention can also include a post - treatment method, and the cooled product can be cut and polished to obtain the alkali - free glass.

[0042] The present invention provides 16 examples. The specific components and performance parameters of the batch formula in Examples 1 - 16 are shown in Table 1.

[0043] Table 1 Glass components and their properties in each example

[0044]

[0045] For the alkali-free glass prepared in Examples 1 to 16 of the present invention, the following methods were used to detect its various properties: Density d: The glass sample was processed to the standard test sample size, and a ZMD series electronic densitometer was used for testing.

[0046] Coefficient of thermal expansion α: The sample was processed into a glass sheet of 50 mm×15 mm, and an Orton DIL2010STD thermomechanical analyzer was used for testing.

[0047] Annealing point and strain point: The sample was drawn into a sample, and an ANS-800 series annealing point and strain point measuring instrument was used for testing.

[0048] Elastic modulus E: The sample was processed to the standard test sample size, polished, without scratches, cracks and corners, and tested according to GB37780-2019.

[0049] Vickers hardness HV and fracture toughness KIC: Using the method of directly measuring the size of the indentation extended crack, the specimen size was 2 mm×4 mm×20 mm, after chamfering, grinding and polishing, after the specimen preparation was completed, a Vickers hardness indenter was used to apply a force of 120 N on the specimen and maintain it for 15 s.

[0050] The results of the various properties of the alkali-free glass prepared in Examples 1 to 16 of the present invention are shown in Table 1. It can be seen from Table 1 that the Young's modulus of the alkali-free glass prepared in Examples 1 to 16 of the present invention is above 80 GPa, the density is less than 2.80 g / cm 3 , the strain point is above 680 °C, and the coefficient of thermal expansion is 35×10 -7 ~50×10 -7 / °C, having properties such as good surface hardness and rigidity, low density, low expansion and high elastic modulus, meeting the application development trend of disk glass.

[0051] The above is only the preferred embodiment of the present invention and is not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An alkali-free glass, characterized in that: Calculated by mass percentage, it includes 50%~70% SiO2, 15%~25% Al2O3, 0~6% B2O3, 1~6% MgO, 0~5% CaO, 0~4% SrO, 0~9% BaO, 0~3% ZnO, 0~3% P2O5, 0~5% Y2O3, 0~3% La2O3, 0~3% TiO2 and 0~5% ZrO2.

2. The alkali-free glass according to claim 1, characterized in that: The invention also comprises a clarifier, wherein the clarifier comprises 0-0.5% SnO2 and / or 0-0.6% CeO2, and the mass percentage of SnO2+CeO2 is 0-0.7%.

3. The alkali-free glass according to claim 1, characterized in that: The mass percentage of SiO2+Al2O3 is 70%~85%; The mass percentage of SiO2+Al2O3+B2O3 is 71.5%~88.85%; The mass percentage of P2O5+ZrO2+TiO2 is 0~4.4%; The mass percentage of Y2O3+La2O3 is 0~5.5%.

4. The alkali-free glass according to claim 1, characterized in that: The Young's modulus of the alkali-free glass is above 80 GPa, and the density is less than 2.80 g / cm 3 .

5. The alkali-free glass according to claim 1, characterized in that: The strain point of the alkali-free glass is above 680°C and the thermal expansion coefficient is 35×10 -7 ~50×10 -7 / ℃.

6. A method for preparing the alkali-free glass according to any one of claims 1 to 5, characterized in that: include: SiO2, Al2O3, B2O3, MgO, CaO, SrO, BaO, ZnO, P2O5, Y2O3, La2O3, TiO2, ZrO2 and a clarifier are uniformly mixed, heated to melt, cooled to form, cooled, annealed, and alkali-free glass is obtained.

7. The method for preparing alkali-free glass according to claim 6, characterized in that: The molding methods include overflow down-draw method and casting method.

8. The method for preparing alkali-free glass according to claim 6, characterized in that: The heating and melting temperature is 1550-1750° C., and the heating and melting time is 1-12 hours.

9. The method for preparing alkali-free glass according to claim 6, characterized in that: The annealing temperature is 600-800° C., and the annealing time is 2-8 hours.

10. A magnetic disk substrate glass, characterized in that: Made of the alkali-free glass according to any one of claims 1 to 5.

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