Preparation method of low-melting-point borosilicate glass high-temperature binder

Abstract

The invention discloses a preparation method of a low-melting-point borosilicate glass high-temperature binder. According to the invention, the borosilicate glass (B2O3.SiO2) high-temperature binder with nano-scale particles is prepared by a sol-gel method, and due to high surface energy and low melting temperature of the nano-scale particles, the melting and bonding temperature of the binder is obviously reduced while the lower content of diboron trioxide (B2O3) is maintained; the invention provides the preparation method of the high-temperature adhesive which has both high-temperature resistance and low-temperature adhesive property. The low-melting-point borosilicate glass high-temperature binder prepared by the invention has excellent low-temperature bonding performance and can keep a stable bonding effect in a high-temperature environment; therefore, the composite material has a wide application prospect in a high-temperature application scene, for example, the composite material plays an important role in connection and packaging of high-temperature parts; the low-melting-point characteristic of the binder is beneficial to reduction of energy consumption and cost in the production process, so that energy consumption is reduced.

Description

Technical Field

[0001] The invention relates to a method for preparing a low-melting-point borosilicate glass high-temperature adhesive, and belongs to the technical field of material chemistry. Background Art

[0002] Borosilicate glass (SiO2·B2O3) is a material with potential application value in high temperature fields, with good chemical stability and high temperature resistance. Among them, the boron trioxide (B2O3) component can effectively reduce its melting point, making it melt and bond at a lower temperature, and is a promising high-temperature adhesive.

[0003] However, borosilicate glass (SiO2·B2O3) high-temperature binders also have some limitations. For example, under certain specific high temperatures and complex environments, their bonding performance may be affected, and bonding failure may easily occur. In order to improve the performance of borosilicate glass (SiO2·B2O3) high-temperature binders, researchers have made many attempts. For example, document 1 "Li H, Wang Y, Zhang J. Enhancement of bonding performance of SiO2·B2O3 binder by adding rare earth oxides. Journal of Materials Science, 2022, 57 (10): 5567-5578." reported that by adding rare earth oxides to the system to form a composite material, its bonding strength and high temperature resistance were significantly improved, and further by heat treatment at a specific temperature, the stability of the binder was enhanced and the performance attenuation at high temperature was reduced. However, this method will increase the preparation cost. Reference 2 "Chen M, Liu Z, Wu X. Analysis of the degradation mechanism of SiO2·B2O3 binder at high temperatures. Materials Chemistry and Physics, 2021, 267: 124557." analyzed the mechanism of performance degradation of borosilicate glass (SiO2·B2O3) binder at high temperatures, and pointed out that phase change, element diffusion and microstructural changes at high temperatures are the main reasons for the degradation of binder performance. Reference 3 "Wang L, Zhao K, Sun F, et al. Effect of pre-treatment on the high-temperature bonding behavior of SiO2·B2O3 based composites at 1000℃[J]. Ceramics International, 2020, 46(17): 26431-26438." reported that by pre-treating borosilicate glass (SiO2-B2O3) based composites at 800℃ for 2 hours, a stable protective layer can be formed on the surface of the material. This protective layer can effectively inhibit element diffusion and phase change at high temperature, significantly improving the bonding performance of SiO2·B2O3 materials at 1000℃. However, this anti-oxidation method is mainly aimed at bulk SiO2·B2O3 materials and has limited effect on powdered adhesives. Therefore, developing a method for preparing a low-melting-point SiO2·B2O3 high-temperature adhesive with superior performance is of great significance for expanding its wide application in high-temperature fields.

[0004] When preparing borosilicate glass (B2O3·SiO2) high-temperature adhesive by the traditional melt reaction method, increasing the content of diboron trioxide (B2O3) can reduce the melt bonding temperature, but at the same time it will lead to an increase in the thermal expansion coefficient and a decrease in heat resistance; when the content of diboron trioxide (B2O3) is reduced, the high-temperature resistance is improved, but its melt bonding temperature and viscosity increase, and the wettability of the bonded components decreases. Therefore, it is difficult for the borosilicate glass (B2O3·SiO2) high-temperature adhesive prepared by the traditional melt reaction method to have both high-temperature resistance and low-temperature bonding performance.

[0005] In the process of chemical reaction and material preparation, although the sol-gel method has many advantages, such as the ability to prepare high-purity and high-uniformity nanomaterials, in practical applications, some unsatisfactory results may be encountered. For the sol-gel method to prepare borosilicate glass (B2O3·SiO2) high-temperature binders with nano-scale particles, the following are some situations that may lead to poor results:

[0006] Particle agglomeration: During the sol-gel process, nano-sized particles tend to agglomerate, resulting in uneven particle size distribution in the final product. This affects the uniformity and consistency of the binder, and thus its performance.

[0007] Residual organic matter: The sol-gel method usually requires the use of organic solvents or additives as reaction media. If the subsequent treatment is not done properly, these organic matter may remain in the binder. These residues may decompose at high temperatures to produce gas, affecting the density and strength of the binder.

[0008] Phase separation: In some cases, the different components in the sol may phase separate during the gelation process, resulting in an inhomogeneous structure of the final product. This can affect the mechanical properties and thermal stability of the borosilicate glass binder.

[0009] Improper heat treatment process: Borosilicate glass adhesives prepared by the sol-gel method usually need to be heat treated to remove residual moisture and organic matter and promote the densification of the glass. However, if the heat treatment is not done properly, it may cause cracks, deformation or performance degradation of the adhesive.

[0010] Raw material purity issues: The purity of the raw materials has a great impact on the performance of the final product. If the B2O3 and SiO2 raw materials used contain impurities, these impurities may introduce defects in the sol-gel process and reduce the performance of the binder.

[0011] Therefore, how to prepare high-purity, high-uniformity borosilicate glass (B2O3·SiO2) high-temperature binder with nanoscale particles by sol-gel method is an urgent problem to be solved. Summary of the invention

[0012] The purpose of the present invention is: in order to solve the technical problem of how to prepare a high-purity, high-uniformity borosilicate glass (B2O3·SiO2) high-temperature adhesive with nanometer-sized particles by a sol-gel method, the present invention provides a method for preparing a low-melting-point borosilicate glass high-temperature adhesive. The present invention prepares a borosilicate glass (B2O3·SiO2) high-temperature adhesive with nanometer-sized particles by a sol-gel method. Due to the high surface energy and low melting temperature of the nanometer-sized particles, the melting and bonding temperature is significantly reduced while maintaining a low boron trioxide (B2O3) content; the present invention provides a method for preparing a high-temperature adhesive that can take into account both high-temperature resistance and low-temperature bonding properties.

[0013] In order to achieve the above object, the present invention provides a method for preparing a low-melting-point borosilicate glass high-temperature adhesive, comprising the following steps:

[0014] Step 1: fully mix anhydrous ethanol and tetraethoxysilane in a flask to obtain a mixed solution; under an ice-water bath, add HCl aqueous solution dropwise while stirring; then add trimethyl borate, continue stirring at room temperature until the reaction solution is clear and transparent; then stir and react under heating conditions;

[0015] Step 2: After the reaction is completed, the mixture is divided into small pieces and sealed, and placed at a constant temperature of 40-60°C to form a gel. After the gel is formed, the mixture is placed to age.

[0016] Step 3: drying the gel obtained after aging in step 2 naturally in air at room temperature;

[0017] Step 4: drying the gel obtained in step 3 at 180-190°C;

[0018] Step 5: heat-treating the gel obtained in step 4 under vacuum conditions, and then cooling to room temperature;

[0019] Step 6: Grind the gel obtained in step 5 to obtain borosilicate glass high-temperature adhesive powder.

[0020] Preferably, in step 1, the volume ratio of anhydrous ethanol, tetraethoxysilane and trimethyl borate is 1-2:8:1.

[0021] More preferably, the volume ratio of anhydrous ethanol, tetraethoxysilane and trimethyl borate is 20.25:84:10.4.

[0022] Preferably, in step 1, the speed of adding the HCl aqueous solution is 1 drop every 2 seconds; the molar concentration of the HCl aqueous solution is 0.1-0.2 mol / L; and the volume ratio of the HCl aqueous solution to anhydrous ethanol is 1:1.

[0023] Preferably, the stirring reaction in step 1 is carried out at a temperature of 40 to 60° C. and for a time of 10 to 24 hours.

[0024] Preferably, the gel aging time in step 2 is 8 to 10 days.

[0025] Preferably, the heat treatment conditions in step 5 are: vacuum pressure 500-1500 Pa, tubular furnace heating rate 4-6° C. / min, and insulation at 1100-1300° C. for 0.5-2 hours.

[0026] The present invention also provides a borosilicate glass high-temperature adhesive prepared by the above preparation method.

[0027] The present invention also provides the use of the borosilicate glass high-temperature adhesive prepared by the above preparation method as a connection and packaging material.

[0028] The borosilicate glass high temperature adhesive prepared by the present invention is used as a connection and packaging material and can be widely used in various fields. Specifically, the borosilicate glass high temperature adhesive prepared by the present invention is mainly used in the following fields:

[0029] Ceramic and electronic industries: In ceramic substrates, electronic packaging and microelectronics technology, borosilicate glass high temperature adhesives are used as connection and packaging materials. Its excellent high temperature resistance and chemical stability ensure the stable operation of electronic components in high temperature environments.

[0030] Aerospace: High temperature adhesives play a key role in the manufacture of aerospace vehicles. They are used to connect various high temperature resistant materials, such as ceramic insulation tiles, high temperature alloys, etc. Borosilicate glass high temperature adhesives prepared by sol-gel method are particularly suitable for such extreme environment applications due to their excellent performance.

[0031] Energy industry: In new energy equipment such as solar cells and fuel cells, borosilicate glass high-temperature adhesives can be used to connect and encapsulate key components such as electrodes and electrolytes. Its high-temperature stability and chemical inertness are essential to ensure the long-term stable operation of the equipment.

[0032] Nuclear industry: In nuclear reactors and nuclear waste treatment, borosilicate glass is used as a solidification material for nuclear waste due to its good neutron absorption and high temperature resistance. The nano-scale borosilicate glass prepared by the sol-gel method further improves its solidification effect, which helps to safely treat nuclear waste.

[0033] Optics and precision instruments: In the manufacture of optical lenses, precision instruments and optical components, borosilicate glass high temperature adhesives can be used to connect and encapsulate key components to ensure their stability and accuracy in high temperatures and complex environments.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention prepares a borosilicate glass (B2O3·SiO2) high-temperature adhesive with nano-scale particles by a sol-gel method. The low-melting-point borosilicate glass high-temperature adhesive prepared by the present invention has excellent low-temperature bonding performance and can maintain a stable bonding effect under high-temperature environment; this makes it have broad application prospects in high-temperature application scenarios, such as playing an important role in the connection and packaging of high-temperature components; the low melting point characteristic of the adhesive helps to reduce energy consumption and cost in the production process, thereby saving energy consumption. DETAILED DESCRIPTION

[0036] In order to make the present invention more clearly understood, preferred embodiments are described in detail as follows.

[0037] In the following examples, the materials and reagents used are all conventional commercially available products unless otherwise specified. Among them, tetraethoxysilane, hydrochloric acid and anhydrous ethanol are analytical grade, and trimethyl borate is reagent grade.

[0038] Example 1

[0039] A method for preparing a low-melting-point borosilicate glass high-temperature adhesive comprises the following steps:

[0040] Step 1: First, 13.5 mL of anhydrous ethanol and 84 mL of tetraethoxysilane were fully mixed in a flask to obtain a mixed solution, which was then placed in an ice water bath.

[0041] Step 2: Under stirring (500-900 rpm), add 13.5 mL of 0.15 mol / L HCl aqueous solution to the mixed solution in the flask in step 1 at a slow and uniform rate.

[0042] Step 3: Under continuous stirring, quickly add 10.4 mL of trimethyl borate to the mixed solution in the flask in step 2.

[0043] Step 4: Remove the flask from the ice-water bath and continue stirring at room temperature until the solution is clear.

[0044] Step 5: Place the flask from step 4 in a 50°C water bath and continue stirring for 17 hours.

[0045] Step 6: After stirring, the solution in the flask in step 5 was divided into plastic bottles, sealed and transferred to a constant temperature water bath at 50°C to wait for gelation. After gelation is formed, continue aging for 10 days before taking out.

[0046] Step 7: Take out the gel obtained in step 6, open the plastic bottle and dry it naturally at room temperature for 5 days.

[0047] Step 8: The dried gel obtained in step 7 was dried at 185°C for 24 hours.

[0048] Step 9: Place the dried gel obtained in step 8 in a high-temperature tube furnace, evacuate to a certain pressure, heat to 1200°C at a heating rate of 5°C / min, maintain at this temperature for 1 hour, and take out after cooling.

[0049] Step 10: Grind the gel obtained by high temperature heat treatment in step 9 in a ball mill for 24 hours to obtain borosilicate glass powder

[0050] Example 2

[0051] A method for preparing a low-melting-point borosilicate glass high-temperature adhesive comprises the following steps:

[0052] Step 1: First, 20.25 mL of anhydrous ethanol and 84 mL of tetraethoxysilane were fully mixed in a flask to obtain a mixed solution, which was then placed in an ice water bath.

[0053] Step 2: Under stirring (500-900 rpm), add 20.2 mL of 0.15 mol / L HCl aqueous solution to the mixed solution in the flask in step 1 at a slow and uniform rate.

[0054] Step 3: Under continuous stirring, quickly add 10.4 mL of trimethyl borate to the mixed solution in the flask in step 2.

[0055] Step 4: Remove the flask from the ice-water bath and continue stirring at room temperature until the solution is clear.

[0056] Step 5: Place the flask from step 4 in a 50°C water bath and continue stirring for 17 hours.

[0057] Step 6: After stirring, the solution in the flask in step 5 was divided into plastic bottles, sealed and transferred to a constant temperature water bath at 50°C to wait for gelation. After gelation is formed, continue aging for 10 days before taking out.

[0058] Step 7: Take out the gel obtained in step 6, open the plastic bottle and dry it naturally at room temperature for 5 days.

[0059] Step 8: Dry the dried gel obtained in step 7 at 185°C for 24 hours.

[0060] Step 9: Place the dried gel obtained in step 8 in a high-temperature tube furnace, evacuate to a certain pressure, heat to 1200°C at a heating rate of 5°C / min, maintain at this temperature for 1 hour, and take out after cooling.

[0061] Step 10: Grind the gel obtained by high temperature heat treatment in step 9 in a ball mill for 24 hours to obtain borosilicate glass powder

[0062] Example 3

[0063] A method for preparing a low-melting-point borosilicate glass high-temperature adhesive comprises the following steps:

[0064] Step 1: First, 16.875 ml of anhydrous ethanol and 84 mL of tetraethoxysilane were fully mixed in a flask to obtain a mixed solution, which was then placed in an ice water bath.

[0065] Step 2: Under stirring (500-900 rpm), add 16.8 mL of 0.15 mol / L HCl aqueous solution to the mixed solution in the flask in step 1 at a slow and uniform rate.

[0066] Step 3: Under continuous stirring, quickly add 10.4 mL of trimethyl borate to the mixed solution in the flask in step 2.

[0067] Step 4: Remove the flask from the ice-water bath and continue stirring at room temperature until the solution is clear.

[0068] Step 5: Place the flask from step 4 in a 50°C water bath and continue stirring for 17 hours.

[0069] Step 6: After stirring, the solution in the flask in step 5 was divided into plastic bottles, sealed and transferred to a constant temperature water bath at 50°C to wait for gelation. After gelation is formed, continue aging for 10 days before taking out.

[0070] Step 7: Take out the gel obtained in step 6, open the plastic bottle and dry it naturally at room temperature for 5 days.

[0071] Step 8: Dry the dried gel obtained in step 7 at 185°C for 24 hours.

[0072] Step 9: Place the dried gel obtained in step 8 in a high-temperature tube furnace, evacuate to a certain pressure, heat to 1200°C at a heating rate of 5°C / min, maintain at this temperature for 1 hour, and take out after cooling.

[0073] Step 10: Grind the gel obtained by high temperature heat treatment in step 9 in a ball mill for 24 hours to obtain borosilicate glass powder

[0074] The boron trioxide (B2O3) content, melt bonding temperature and theoretical melting temperature of Example 1, Example 2 and Example 3 are shown in Table 1.

[0075] Table 1 Comparison of boron trioxide (B2O3) content, melting bonding temperature and theoretical melting temperature of Example 1, Example 2 and Example 3

[0076]

[0077] Note: The theoretical melting bonding temperature is obtained based on the binary phase diagram of SiO2·B2O3.

[0078] It can be seen from Table 1 that the melting bonding temperatures of the three embodiments are significantly lower than their theoretical melting temperatures, and have good low-temperature melting bonding performance. Among them, the melting bonding temperature of embodiment 2 is the lowest, with a difference of 594°C from its theoretical melting temperature, the largest difference, and the best low-temperature bonding performance.

[0079] The above description is only a preferred embodiment of the present invention and is not any formal or substantial limitation of the present invention. It should be pointed out that a person skilled in the art can make several improvements and supplements without departing from the present invention, and these improvements and supplements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a low melting point borosilicate glass high temperature adhesive, characterized in that: The following steps are involved: Step 1: fully mix anhydrous ethanol and tetraethoxysilane in a flask to obtain a mixed solution; under an ice-water bath, add HCl aqueous solution dropwise while stirring; then add trimethyl borate, continue stirring at room temperature until the reaction solution is clear and transparent; then stir and react under heating conditions; Step 2: After the reaction is completed, the mixture is divided into small pieces and sealed, and placed at a constant temperature of 40-60°C to form a gel. After the gel is formed, the mixture is placed to age. Step 3: drying the gel obtained after aging in step 2 naturally in air at room temperature; Step 4: drying the gel obtained in step 3 at 180-190°C; Step 5: heat-treating the gel obtained in step 4 under vacuum conditions, and then cooling to room temperature; Step 6: Grind the gel obtained in step 5 to obtain borosilicate glass high-temperature adhesive powder.

2. The preparation method according to claim 1, characterized in that: In the step 1, the volume ratio of anhydrous ethanol, tetraethoxysilane and trimethyl borate is 1-2:8:

1.

3. The preparation method according to claim 1, characterized in that: The speed of adding the HCl aqueous solution in step 1 is 1 drop every 2 seconds; the molar concentration of the HCl aqueous solution is 0.1-0.2 mol / L; and the volume ratio of the HCl aqueous solution to anhydrous ethanol is 1:

1.

4. The preparation method according to claim 1, characterized in that: The stirring reaction in step 1 is performed at a temperature of 40 to 60° C. for 10 to 24 hours.

5. The preparation method according to claim 1, characterized in that: The gel aging time in step 2 is 8 to 10 days.

6. The preparation method according to claim 1, characterized in that: The heat treatment conditions in step 5 are: vacuum pressure 500-1500 Pa, tubular furnace heating rate 4-6° C. / min, and heat preservation at 1100-1300° C. for 0.5-2 hours.

7. Borosilicate glass high temperature adhesive prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the borosilicate glass high temperature adhesive prepared by the preparation method according to any one of claims 1 to 6 as a connection and packaging material.

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