A sealing multi-phase ceramic with adjustable coefficient of thermal expansion and a preparation method thereof

Abstract

This invention discloses a multiphase ceramic for sealing with adjustable thermal expansion coefficient and its preparation method. The multiphase ceramic comprises an expanding phase and a matrix phase. The matrix phase is mainly composed of Li₂O and SiO₂, with at least one of B₂O₃, Al₂O₃, MgO, Na₂O, ZrO₂, and La₂O₃ as a modifier. The thermal expansion coefficient of the multiphase ceramic is controlled by adjusting the ratio of the high thermal expansion phase to the matrix phase. In this preparation method, the quartz raw material is introduced into the matrix phase in a single step, eliminating the need for a long and complex heat treatment process to induce cristobalite growth, thus improving the production efficiency in the sealing process of electronic devices.

Description

Technical Field

[0001] This invention relates to the field of ceramic-metal sealing materials technology, and in particular to a multiphase ceramic for sealing with adjustable thermal expansion coefficient and its preparation method. Background Technology

[0002] Heterogeneous material devices possess significant technical and economic value due to their ability to combine the superior properties of different materials, enhancing design and manufacturing flexibility and meeting the demands of modern industrial technology for multifunctional and high-performance devices. To ensure the development of component packaging towards high power, high integration, and miniaturization, the connection between ceramic materials and metals, which possess high strength, oxidation resistance, corrosion resistance, and high electrical insulation, has become a key area of ​​focus.

[0003] To achieve a matching seal with 304L stainless steel, existing methods introduce nucleating agents to induce the growth of cristobalite phase during heat treatment, thereby controlling the thermal expansion coefficient of the glass-ceramic. This method has several drawbacks: First, cristobalite undergoes a volumetric phase transformation at 200–300℃, causing a sudden change in the thermal expansion coefficient of the glass-ceramic, which can lead to cracking during the sealing and cooling stage. Second, the slow growth rate of cristobalite results in long heat treatment times and high energy consumption during the sealing process. Third, the process is complex and requires sophisticated equipment; this method employs multi-stage heat treatment to induce the growth of both cristobalite and quartz, making the required equipment and process conditions even more complex. Summary of the Invention

[0004] This invention provides a multiphase ceramic for sealing with adjustable thermal expansion coefficient and its preparation method, which overcomes the defects of existing technologies such as easy cracking during the sealing process, long heat treatment time, high energy consumption, and complex preparation process.

[0005] To achieve the above objectives, this invention proposes a multiphase ceramic with adjustable thermal expansion coefficient. The multiphase ceramic comprises an expanded phase and a matrix phase. The expanded phase is a quartz crystal, and the matrix phase is composed of Li2O-SiO2-RO, wherein RO is at least one of B2O3, Al2O3, MgO, Na2O, ZrO2, and La2O3. The mass ratio of the matrix phase to the expanded phase is (60-90):(10-40).

[0006] To achieve the above objectives, the present invention also proposes a method for preparing a multiphase ceramic with an adjustable coefficient of thermal expansion as described above, comprising the following steps:

[0007] S1: Weigh the raw materials according to the mass ratio of SiO2 70-80%, Li2CO3 10-20%, H3BO3 7.5-15%, MgO 0-3%, Al2O3 0-2%, Na2CO3 0-2%, La2O3 0-1%, and ZrO2 0-1%, mix them well to obtain a mixture;

[0008] S2: The mixture is melted to obtain a clear glass melt;

[0009] S3: The glass melt is quenched in deionized water and then taken out, the glass slag is dried, and the glass slag is ball-milled to obtain the matrix phase;

[0010] S4: Select quartz raw material and ball mill it to obtain the expanded phase;

[0011] S5: The matrix phase and the expanded phase are mixed at a specific mass ratio of (60-90):(10-40), a binder is added to prepare a slurry, granulated, and pressed to obtain a composite ceramic body;

[0012] S6: Heat the composite ceramic blank to 450-500℃ and hold for 15-60 minutes; then raise the temperature to 800-1000℃ for high-temperature sintering and hold for 0.5-2 hours to obtain the multiphase ceramic.

[0013] To achieve the above objectives, the present invention also proposes an application of a multiphase ceramic with an adjustable coefficient of thermal expansion, wherein the multiphase ceramic described above or the multiphase ceramic prepared by the above preparation method is applied to the matching and sealing of 304L stainless steel.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] 1. The thermally expandable multiphase ceramic provided by this invention comprises an expanding phase and a matrix phase. The matrix phase is mainly composed of Li2O and SiO2, with at least one of B2O3, Al2O3, MgO, Na2O, ZrO2, and La2O3 as a modifier. The thermal expansion coefficient of the multiphase ceramic is controlled by adjusting the ratio of the high thermal expansion phase to the matrix phase. Simultaneously, this invention uses a quartz high thermal expansion phase to replace the cristobalite high thermal expansion phase in the original technical solution, thereby avoiding the excessive precipitation of cristobalite and reducing the generation of seal cracks during the sealing process.

[0016] 2. The multiphase ceramic with adjustable thermal expansion coefficient provided by this invention exhibits excellent high-temperature stability. Traditional high-thermal-expansion sealing glass reacts with quartz precipitated in the matrix phase to form a low-thermal-expansion phase, Li2Si2O5, in high-temperature service environments. This invention effectively avoids this harmful reaction by introducing a quartz phase, significantly improving the high-temperature stability of the multiphase ceramic.

[0017] 3. The method for preparing multiphase ceramics with adjustable thermal expansion coefficient provided by this invention introduces quartz raw material into the matrix phase in a single step, eliminating the need for lengthy and complex heat treatment processes to induce cristobalite growth, thus improving production efficiency in the sealing process of electronic devices. Furthermore, this preparation method features simple process conditions; the prepared multiphase ceramics only require a single heat treatment cycle to complete the sealing process, requiring minimal heating equipment and resulting in low cost. It can be well applied to the matching sealing of metal materials such as 304L stainless steel. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0019] Figure 1 The graph shows the thermal expansion coefficient of the multiphase ceramic in Example 1.

[0020] Figure 2 This is the X-ray diffraction pattern of the expanded phase in Example 1.

[0021] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0024] Unless otherwise specified, all medicines / reagents used are commercially available.

[0025] This invention proposes a multiphase ceramic with adjustable thermal expansion coefficient, the multiphase ceramic comprising an expanded phase and a matrix phase, the expanded phase being quartz crystal, and the matrix phase being composed of Li2O-SiO2-RO, wherein RO is at least one of B2O3, Al2O3, MgO, Na2O, ZrO2, and La2O3; the mass ratio of the matrix phase to the expanded phase is (60-90):(10-40).

[0026] Preferably, the thermal expansion coefficient of the sealing multiphase ceramic can be adjusted by adjusting the quartz crystal content in the multiphase ceramic. The thermal expansion coefficient of the multiphase ceramic can be adjusted in the range of 9.4 to 16.2 ppm / ℃ and the temperature range is 25 to 500℃.

[0027] This invention also proposes a method for preparing multiphase ceramics with adjustable thermal expansion coefficients as described above, comprising the following steps:

[0028] S1: Weigh the raw materials according to the mass ratio of SiO2 70-80%, Li2CO3 10-20%, H3BO3 7.5-15%, MgO 0-3%, Al2O3 0-2%, Na2CO3 0-2%, La2O3 0-1%, and ZrO2 0-1%, mix them well to obtain a mixture;

[0029] S2: The mixture is melted to obtain a clear glass melt;

[0030] S3: The glass melt is quenched in deionized water and then taken out, the glass slag is dried, and the glass slag is ball-milled to obtain the matrix phase;

[0031] S4: Select quartz raw material and ball mill it to obtain the expanded phase;

[0032] S5: The matrix phase and the expanded phase are mixed at a mass ratio of (60-90):(10-40), a binder is added to prepare a slurry, granulated, and pressed to obtain a composite ceramic body;

[0033] S6: Heat the composite ceramic blank to 450-500℃ and hold for 15-60 minutes; then raise the temperature to 800-1000℃ for high-temperature sintering and hold for 0.5-2 hours to obtain the multiphase ceramic.

[0034] Preferably, in step S1, the mixing specifically involves:

[0035] The raw materials are mixed evenly in a mixer with zirconium balls added, and the mixing time is 6 to 12 hours.

[0036] Preferably, in step S2, the smelting specifically involves:

[0037] The mixture is placed in a melting furnace and heated to 1400-1550°C, and kept at that temperature for 3-5 hours.

[0038] Preferably, in step S3, the particle size of the matrix phase is 1-5 μm; the ball milling speed is 600-700 rpm; and the ambient temperature is 20-25℃.

[0039] Preferably, in step S4, the quartz raw material is quartz microspheres or silica microspheres; the particle size of the quartz microspheres is 1-100 μm, and the particle size of the silica microspheres is 100-500 nm.

[0040] Preferably, if silica microspheres are selected, the following steps are also required:

[0041] Defects were introduced on the surface of silica microspheres, and quartz microspheres were obtained by heat treatment at 500–800℃ for 7–9 hours.

[0042] Preferably, in step S5, the pressing pressure is 0.5 to 0.6 MPa.

[0043] The present invention also proposes an application of a multiphase ceramic with an adjustable coefficient of thermal expansion, which is used in the matching and sealing of 304L stainless steel.

[0044] The multiphase ceramic of this invention is assembled with 304L stainless steel or other metal materials using a graphite mold. In an inert atmosphere, the temperature is increased to 900–1100°C at a rate of 2–15°C / min for sealing. After sealing, a high thermal expansion seal body with good bonding to 304L stainless steel or other metal materials is obtained.

[0045] Example 1

[0046] This embodiment provides a multiphase ceramic with adjustable thermal expansion coefficient. The multiphase ceramic includes an expanded phase and a matrix phase. The expanded phase is quartz crystal, and the matrix phase is composed of Li2O-SiO2-RO, wherein RO is at least one of B2O3, Al2O3, MgO, Na2O, ZrO2 and La2O3; the quartz crystal content in the multiphase ceramic is 40%.

[0047] This embodiment also provides a method for preparing the above-mentioned multiphase ceramic, including the following steps:

[0048] S1: Weigh the raw materials according to the mass ratio of SiO2 71.20%, Li2CO3 13.57%, H3BO3 9.28%, MgO 2.5%, Na2CO3 1.75%, La2O3 0.87%, and ZrO2 0.83%. Mix the raw materials thoroughly and evenly in a mixer with zirconium balls for 7 hours to obtain a mixture.

[0049] S2: Place the mixture in a melting furnace and heat it to 1450℃, hold it for 3 hours, and obtain a clear glass melt;

[0050] S3: After quenching the molten glass in deionized water, remove it, dry the glass slag, and ball mill the glass slag to d. 50 The particle size was 1–2 μm, the ball milling time was 1 h, the ball milling speed was 700 rpm, and the ball milling ambient temperature was 22 °C, to obtain the matrix phase;

[0051] S4: Select quartz raw material and ball mill it to obtain the expanded phase. Its X-ray diffraction pattern is as follows: Figure 2 As shown;

[0052] S5: The matrix phase and the expanded phase are mixed at a mass ratio of 60:40. 5% PVA is mixed at a mass ratio of 1% to form a slurry. The slurry is then granulated into balls in a spray granulator. The granulated composite powder is then pressed into shape under a pressure of 0.6 MPa to obtain a composite ceramic green body.

[0053] S6: The composite ceramic green body is heated to 500°C at a heating rate of 5°C / min and held for 15 min to remove organic matter from the green body; then heated to 955°C for high-temperature sintering and held for 0.5 h to obtain multiphase ceramic.

[0054] S6: Assemble the multiphase ceramic and 304L stainless steel or other metal materials using a graphite mold. Under a flowing nitrogen atmosphere, heat to 980°C at a heating rate of 8°C / min, hold for 10 minutes, and cool after sealing to obtain a high thermal expansion seal that bonds well with 304L stainless steel or other metal materials.

[0055] The density and coefficient of thermal expansion of the multiphase ceramic prepared in this embodiment were tested, and the density was 2.29 g / cm³. 3 The coefficient of thermal expansion is 16.2 ppm / K (e.g., Figure 1 As shown), the density of the sealant without the addition of a high thermal expansion phase is 2.30 g / cm³. 3 The coefficient of thermal expansion is 9.4 ppm / K, which achieves the purpose of adjusting the coefficient of thermal expansion.

[0056] Example 2

[0057] This embodiment provides a multiphase ceramic with adjustable thermal expansion coefficient. The multiphase ceramic includes an expanded phase and a matrix phase. The expanded phase is quartz crystal, and the matrix phase is composed of Li2O-SiO2-RO, wherein RO is at least one of B2O3, Al2O3, MgO, Na2O, ZrO2 and La2O3; the quartz crystal content in the multiphase ceramic is 30%.

[0058] This embodiment also provides a method for preparing the above-mentioned multiphase ceramic, including the following steps:

[0059] S1: Weigh the raw materials according to the mass ratio of SiO2 74.20%, Li2CO3 12.57%, H3BO3 8.83%, MgO 2.23%, Na2CO3 1.25%, La2O3 0.34%, and ZrO2 0.58%. Mix the raw materials thoroughly and evenly in a mixer with zirconium balls for 12 hours to obtain a mixture.

[0060] S2: Place the mixture in a melting furnace and heat it to 1450℃, hold it for 5 hours, and obtain a clear glass melt;

[0061] S3: After quenching the molten glass in deionized water, remove it, dry the glass slag, and ball mill the glass slag to d. 50 The particle size was 2.5–5 μm, the ball milling time was 0.8 h, the ball milling speed was 650 rpm, and the ball milling ambient temperature was 22 °C, to obtain the matrix phase;

[0062] S4: Spherical silica particles with a diameter of 200 nm were acid-washed with 4 mol / L hydrochloric acid, then washed twice with deionized water, and dried at 100 °C for 5 h. Subsequently, the dried spherical silica particles were heat-treated in a muffle furnace at a temperature of 573 °C, a heating rate of 10 °C / min, and a holding time of 7 h. After the heat treatment, quartz microspheres, i.e., the expanded phase, were obtained.

[0063] S5: The matrix phase and the expanded phase are mixed at a mass ratio of 70:30. 5% PVA is mixed at a mass ratio of 1% to form a slurry. The slurry is then granulated into balls in a spray granulator. The granulated composite powder is then pressed into shape under a pressure of 0.6 MPa to obtain a composite ceramic green body.

[0064] S6: The composite ceramic green body is heated to 500°C at a heating rate of 10°C / min and held for 15 min to remove organic matter from the green body; then heated to 950°C for high-temperature sintering and held for 0.5 h to obtain multiphase ceramic.

[0065] S6: Assemble the multiphase ceramic and 304L stainless steel or other metal materials using a graphite mold. Under a flowing nitrogen atmosphere, heat to 960°C at a heating rate of 5°C / min, hold for 20 minutes, and cool after sealing to obtain a high thermal expansion seal that bonds well with 304L stainless steel or other metal materials.

[0066] The density and coefficient of thermal expansion of the multiphase ceramic prepared in this embodiment were tested, and the density was 2.31 g / cm³. 3The coefficient of thermal expansion is 13.4 ppm / K, and the density of the same sealant without the addition of a high thermal expansion phase is 2.30 g / cm³. 3 The coefficient of thermal expansion is 9.4 ppm / K, which achieves the purpose of adjusting the coefficient of thermal expansion.

[0067] Example 3

[0068] This embodiment provides a multiphase ceramic with adjustable thermal expansion coefficient. The multiphase ceramic includes an expanded phase and a matrix phase. The expanded phase is quartz crystal, and the matrix phase is composed of Li2O-SiO2-RO, wherein RO is at least one of B2O3, Al2O3, MgO, Na2O, ZrO2 and La2O3; the quartz crystal content in the multiphase ceramic is 10%.

[0069] This embodiment also provides a method for preparing the above-mentioned multiphase ceramic, including the following steps:

[0070] S1: Weigh the raw materials according to the mass ratio of SiO2 70.20%, Li2CO3 14.02%, H3BO3 10.83%, MgO 3.00%, Na2CO3 1.28%, and ZrO2 0.67%. Mix the raw materials thoroughly and evenly in a mixer with zirconium balls for 12 hours to obtain a mixture.

[0071] S2: Place the mixture in a melting furnace and heat it to 1500℃, hold it at that temperature for 4 hours, and obtain a clear glass melt;

[0072] S3: After quenching the molten glass in deionized water, remove it, dry the glass slag, and ball mill the glass slag to d. 50 The particle size was 1.5–3.5 μm, the ball milling time was 1.5 h, the ball milling speed was 650 rpm, and the ball milling ambient temperature was 22 °C, to obtain the matrix phase;

[0073] S4: Spherical silica particles with a diameter of 500 nm were acid-washed with 4 mol / L hydrochloric acid, then washed twice with deionized water, and dried at 100 °C for 5 h. Subsequently, the dried spherical silica particles were heat-treated in a muffle furnace at a temperature of 573 °C, a heating rate of 10 °C / min, and a holding time of 7 h. After the heat treatment, quartz microspheres, i.e., the expanded phase, were obtained.

[0074] S5: The matrix phase and the expanded phase are mixed at a mass ratio of 90:10. 5% PVA is mixed at a mass ratio of 1% to form a slurry. The slurry is then granulated into balls in a spray granulator. The granulated composite powder is then pressed into shape under a pressure of 0.6 MPa to obtain a composite ceramic green body.

[0075] S6: The composite ceramic green body is heated to 500°C at a heating rate of 10°C / min and held for 15 min to remove organic matter from the green body; then heated to 890°C for high-temperature sintering and held for 0.5 h to obtain multiphase ceramic.

[0076] S6: Assemble the multiphase ceramic and 304L stainless steel or other metal materials using a graphite mold. Under a flowing nitrogen atmosphere, heat to 980°C at a heating rate of 8°C / min, hold for 10 minutes, and cool after sealing to obtain a high thermal expansion seal that bonds well with 304L stainless steel or other metal materials.

[0077] The density and coefficient of thermal expansion of the multiphase ceramic prepared in this embodiment were tested, and the density was 2.32 g / cm³. 3 The coefficient of thermal expansion is 11.2 ppm / K, and the density of the same sealant without the addition of a high thermal expansion phase is 2.30 g / cm³. 3 The coefficient of thermal expansion is 9.4 ppm / K, which achieves the purpose of adjusting the coefficient of thermal expansion.

[0078] As can be seen from Examples 1-3, the coefficient of thermal expansion of multiphase ceramics can be effectively controlled by adjusting the ratio of the high thermal expansion phase to the matrix phase. The higher the proportion of the expansion phase, the higher the coefficient of thermal expansion. Specifically, when the content of the expansion phase is 0-40%, the adjustable range of the coefficient of thermal expansion is 9.4-16.2 ppm / K.

[0079] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A multiphase ceramic with an adjustable coefficient of thermal expansion, characterized in that, The multiphase ceramic comprises an expanded phase and a matrix phase. The expanded phase is a quartz crystal, and the matrix phase is composed of Li2O-SiO2-RO, wherein RO is B2O3, MgO, Na2O, ZrO2, and La2O3. The mass ratio of the matrix phase to the expanded phase is (60~70):(30~40). The multiphase ceramic is prepared by the following method: S1: Weigh the raw materials according to the following mass ratios: SiO2 71.2~74.2%, Li2CO3 12.57~13.57%, H3BO3 8.83~9.28%, MgO 2.23~2.5%, Na2CO3 1.25~1.75%, La2O3 0.34~0.87%, ZrO2 0.58~0.83%, mix them well, and obtain the mixture. S2: The mixture is melted at 1400~1550℃ and held for 3~5 hours to obtain a clear glass melt; S3: After quenching the molten glass in deionized water, remove it, dry the glass slag, and ball mill the glass slag until... d 50 The particle size is 1~5 μm, the ball milling speed is 600~700 rpm, and the ball milling ambient temperature is 20~25℃ to obtain the matrix phase; S4: Select quartz crystal raw materials and ball mill them to obtain the expanded phase; S5: The matrix phase and the expanded phase are mixed at a mass ratio of (60~70):(30~40), a binder is added to prepare a slurry, granulated, and pressed into shape at 0.5~0.6 MPa to obtain a composite ceramic green body; S6: Heat the composite ceramic blank to 450~500℃ and hold for 15~60min; then raise the temperature to 800~1000℃ for high-temperature sintering and hold for 0.5~2h to obtain the multiphase ceramic.

2. The multiphase ceramic with adjustable thermal expansion coefficient according to claim 1, characterized in that, The coefficient of thermal expansion of the multiphase ceramic is adjustable in the range of 9.4~16.2 ppm / ℃, and the temperature range is 25~500℃.

3. A method for preparing a multiphase ceramic with an adjustable coefficient of thermal expansion according to claim 1 or 2, characterized in that, Includes the following steps: S1: Weigh the raw materials according to the following mass ratios: SiO2 71.2~74.2%, Li2CO3 12.57~13.57%, H3BO3 8.83~9.28%, MgO 2.23~2.5%, Na2CO3 1.25~1.75%, La2O3 0.34~0.87%, ZrO2 0.58~0.83%, mix them well, and obtain the mixture. S2: The mixture is melted at 1400~1550℃ and held for 3~5 hours to obtain a clear glass melt; S3: After quenching the molten glass in deionized water, remove it, dry the glass slag, and ball mill the glass slag until... d 50 The particle size is 1~5 μm, the ball milling speed is 600~700 rpm, and the ball milling ambient temperature is 20~25℃ to obtain the matrix phase; S4: Select quartz crystal raw materials and ball mill them to obtain the expanded phase; S5: The matrix phase and the expanded phase are mixed at a mass ratio of (60~70):(30~40), a binder is added to prepare a slurry, granulated, and pressed into shape at 0.5~0.6 MPa to obtain a composite ceramic green body; S6: Heat the composite ceramic blank to 450~500℃ and hold for 15~60min; then raise the temperature to 800~1000℃ for high-temperature sintering and hold for 0.5~2h to obtain the multiphase ceramic.

4. The method for preparing a multiphase ceramic with adjustable thermal expansion coefficient according to claim 3, characterized in that, In step S1, the mixing specifically involves: The raw materials are mixed evenly in a mixer with zirconium balls added, and the mixing time is 6~12 hours.

5. The method for preparing a multiphase ceramic with adjustable thermal expansion coefficient according to claim 3, characterized in that, In step S4, the quartz crystal raw material is quartz microspheres or silica microspheres; the particle size of the quartz microspheres is 1~100 μm, and the particle size of the silica microspheres is 100~500 nm.

6. The method for preparing a multiphase ceramic with adjustable thermal expansion coefficient according to claim 3, characterized in that, When selecting silica microspheres, the following steps are also required: Defects are introduced on the surface of silica microspheres, and quartz microspheres are obtained by heat treatment at 500~800℃ for 7~9h.

7. An application of a multiphase ceramic with an adjustable coefficient of thermal expansion, characterized in that, The multiphase ceramic prepared by the method of preparing a multiphase ceramic with adjustable thermal expansion coefficient as described in claim 1 or 2, or a multiphase ceramic with adjustable thermal expansion coefficient as described in any one of claims 3 to 6, is applied to the matching sealing of 304L stainless steel, and is sealed at 900 to 1100°C in an inert atmosphere at a heating rate of 2 to 15°C / min.

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