Aluminum powder sintered foil and preparation method and application thereof

Abstract

The invention discloses an aluminum powder sintered foil and a preparation method and application thereof, and belongs to the technical field of sintered foil preparation.The aluminum powder sintered foil is prepared by taking an aluminum light foil and aluminum powder as raw materials, matching the [111] crystal face orientation of the aluminum light foil and the aluminum powder, enabling the [111] crystal face relative texture coefficient of at least one of the aluminum light foil and the aluminum powder to be larger than or equal to 90%, laying the aluminum powder on the surface of the aluminum light foil, and preparing the aluminum powder sintered foil in a protective gas atmosphere. And sintering at the temperature of 580-640 DEG C to obtain the aluminum powder sintered foil. According to the invention, by regulating and controlling the orientation matching of the [111] crystal face of the aluminum light foil and the aluminum powder, the interface diffusion barrier is obviously reduced, and the low-temperature sintering at 580-640 DEG C is realized. The material is suitable for an anode of a high-specific-volume aluminum electrolytic capacitor, the volumetric specific capacity can be improved by 30%-50%, and key technical support is provided for a miniaturized and high-energy-density capacitor.

Description

Technical Field

[0001] The present invention relates to the technical field of sintered foil preparation, and particularly relates to an aluminum powder sintered foil, a preparation method thereof and an application thereof. Background Art

[0002] In the field of electronic components, aluminum powder sintered foil is expected to be applied to aluminum electrolytic capacitors to greatly improve their volume specific capacitance and energy density, and reduce the volume and weight of electrolytic capacitors because it has a much higher specific capacitance than traditional etched foils. The traditional aluminum powder sintering process usually uses high-temperature sintering above 600 °C. Although it can achieve material bonding, there are significant defects: 1) High temperature causes violent diffusion of aluminum atoms, easily leading to neck coarsening and porosity reduction of the sintering, reducing the flexibility and specific surface area of the aluminum foil; 2) High temperature increases energy consumption, raises production costs and does not conform to the trend of green manufacturing.

[0003] How to reduce the sintering temperature is a current research hotspot and difficulty. During the sintering process, the main factor affecting the diffusion rate of aluminum atoms is the interfacial barrier between the aluminum substrate and the aluminum powder. The higher the interfacial barrier, the higher the energy required for aluminum atoms to cross this barrier. Only by raising the temperature of the aluminum powder can higher energy be obtained. Therefore, how to reduce the interfacial barrier is of great significance for obtaining low-temperature sintering. Summary of the Invention

[0004] The present invention provides an aluminum powder sintered foil, a preparation method thereof and an application thereof. Aiming at the problems such as reduced porosity, high energy consumption and poor flexibility caused by traditional high-temperature sintering (>600 °C) of aluminum powder, the present invention significantly reduces the interfacial diffusion barrier by regulating the

[111] crystal plane orientation of the aluminum bright foil and the aluminum powder, achieving a double breakthrough in reducing the sintering temperature and improving the material properties.

[0005] The first object of the present invention is to provide a preparation method of an aluminum powder sintered foil, comprising the following steps: Using an aluminum bright foil and aluminum powder as raw materials, and matching the

[111] crystal plane orientation of the aluminum bright foil and the aluminum powder so that the relative texture coefficient of the

[111] crystal plane of at least one party is ≥90%. Lay the aluminum powder on the surface of the aluminum bright foil, and sinter at 580 °C to 640 °C under a protective gas atmosphere to obtain the aluminum powder sintered foil.

[0006] As a preferred embodiment, the relative texture coefficient of the

[111] crystal plane of the aluminum bright foil is ≥90%, the crystal plane orientation of the aluminum powder is at least one of the

[200] ,

[220] or

[311] crystal planes, and the relative texture coefficient of the aluminum powder crystal plane is ≥80%.

[0007] As a preferred embodiment, the relative texture coefficient of the

[111] crystal plane of the aluminum powder is 90%, the crystal plane orientation of the aluminum bright foil is at least one of the

[200] ,

[220] or

[311] crystal planes, and the relative texture coefficient of the aluminum bright foil crystal plane is ≥80%.

[0008] As a preferred embodiment, the thickness of the aluminum foil is 10 μm to 650 μm, and the particle size of the aluminum powder is 1 μm to 10 μm.

[0009] As a preferred embodiment, during the sintering process, the heating rate is 0.1 °C / min to 15 °C / min, the holding time is 1 h to 24 h, and the pressure is 0.1 MPa to 1 MPa.

[0010] As a preferred embodiment, when the sintering temperature is 580 °C to 600 °C, the holding time is ≥ 8 h; when the temperature is 620 °C to 640 °C, the constant temperature time is ≥ 1 h.

[0011] As a preferred embodiment, the protective gas is selected from at least one of argon, nitrogen, helium, carbon dioxide, carbon monoxide, and hydrogen, with an oxygen content < 1 ppm and a water content < 1 ppm.

[0012] The second object of the present invention is to provide an aluminum powder sintered foil prepared by the above preparation method.

[0013] As a preferred embodiment, the withstand voltage value of the aluminum powder sintered foil is ≥ 615 V, and the specific capacitance is ≥ 0.69 μF / cm 2 .

[0014] The third object of the present invention is to provide the application of the above aluminum powder sintered foil as an anode material in an aluminum electrolytic capacitor.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a preparation method of an aluminum powder sintered foil. By regulating the

[111] crystal plane orientation of the aluminum foil and the aluminum powder, the interfacial diffusion barrier is significantly reduced, achieving a double breakthrough in reducing the sintering temperature and improving the material properties; among them, when the relative texture coefficient of the

[111] crystal plane of the aluminum powder is ≥ 90%, it has high surface activity: its dense atomic arrangement provides more active sites, promoting the adsorption and diffusion of aluminum atoms; it has a low activation energy: reducing the atomic migration barrier, enabling sintering to be completed at 580 °C to 640 °C; lattice matching: when the crystal plane orientations of the light foil and the aluminum powder are consistent, the interfacial defects are reduced, and the sintering bonding strength is improved.

[0016] The aluminum powder sintered foil prepared by the present invention is suitable for the anode of a high specific capacitance aluminum electrolytic capacitor, and can increase the volume specific capacitance by 30% to 50%, providing key technical support for miniaturized and high energy density capacitors. Specific embodiments

[0017] In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the present invention will be further described below in conjunction with specific embodiments, but the exemplified embodiments shall not be construed as limiting the present invention. The following test methods and detection methods are all conventional methods unless otherwise specified; the reagents and raw materials are all commercially available unless otherwise specified.

[0018] For the existing aluminum powder sintering process, high-temperature sintering at above 600°C is usually adopted. Although material bonding can be achieved, there are significant defects: 1) High temperature causes intense diffusion of aluminum atoms, easily leading to neck thickening of sintering and reduction of porosity, reducing the flexibility and specific surface area of aluminum foil; 2) High temperature increases energy consumption, raises production costs and does not conform to the trend of green manufacturing. Based on the above technical problems, the present invention provides an aluminum powder sintered foil, its preparation method and application.

[0019] The technical solution of the present invention will be described in detail below.

[0020] The present invention provides a method for preparing an aluminum powder sintered foil, comprising the following steps: Using aluminum bright foil and aluminum powder as raw materials, and matching the

[111] crystal plane orientation of the aluminum bright foil and the aluminum powder, so that the relative texture coefficient of the

[111] crystal plane of at least one party is ≥90%. Lay the aluminum powder on the surface of the aluminum bright foil, and sinter at 580°C to 640°C under the atmosphere of protective gas to obtain the aluminum powder sintered foil.

[0021] It should be noted that in order to solve the problems of reduced porosity, high energy consumption and poor flexibility caused by traditional high-temperature sintering (>600°C) of aluminum powder, by regulating the

[111] crystal plane orientation of the aluminum bright foil and the aluminum powder, the relative texture coefficient of the

[111] crystal plane of at least one of the aluminum bright foil and the aluminum powder is ≥90%, significantly reducing the interfacial diffusion barrier, promoting the surface migration of atoms, and being conducive to the formation of sintering necks during the sintering process, achieving a double breakthrough in reducing the sintering temperature and improving the material properties.

[0022] In some embodiments, the relative texture coefficient of the

[111] crystal plane of the aluminum bright foil is ≥90%, the crystal plane orientation of the aluminum powder is at least one of the

[200] ,

[220] or

[311] crystal planes, and the relative texture coefficient of the aluminum powder crystal plane is ≥80%.

[0023] In some embodiments, the relative texture coefficient of the

[111] crystal plane of the aluminum powder is ≥90%, the crystal plane orientation of the aluminum bright foil is at least one of the

[200] ,

[220] or

[311] crystal planes, and the relative texture coefficient of the aluminum bright foil crystal plane is ≥80%.

[0024] It should be noted that in the present invention, the relative texture coefficient of the

[111] crystal plane of the aluminum powder is ≥90%, which has high surface activity: its dense atomic arrangement provides more active sites, promoting the adsorption and diffusion of aluminum atoms; it has a low activation energy: reducing the atomic migration barrier, enabling sintering to be completed at 580°C to 640°C; lattice matching: when the crystal plane orientation of the light foil and the aluminum powder is the same, the interface defects are reduced, and the sintering bonding strength is improved.

[0025] In some embodiments, the thickness of the aluminum light foil is 10 μm to 650 μm, and the particle size of the aluminum powder is 1 μm to 10 μm. It should be noted that as a preferred solution of the present invention, the thickness of the aluminum light foil is 10 μm to 650 μm. If the thickness of the aluminum light foil is too low, it is likely to cause the coating layer formed by the aluminum powder to be unable to be supported, and if the thickness is too thick, it is likely to result in poor performance of the aluminum powder sintered foil. As a preferred solution of the present invention, the particle size of the aluminum powder is 1 μm to 10 μm. The particle size of the aluminum powder affects the porosity of the powder sintered foil obtained by preparation. If the particle size is too low or too large, it is likely to cause the porosity to decrease, thereby affecting the performance of the aluminum powder sintered foil.

[0026] In some embodiments, during the sintering process, the heating rate is 0.1°C / min to 15°C / min, the holding time is 1 h to 24 h, and the pressure is 0.1 MPa to 1 MPa. It should be noted that as a preferred solution of the present invention, by sintering under a pressure of 0.1 MPa to 1 MPa, the performance of the aluminum powder sintered foil can be precisely optimized, promoting grain boundary migration and particle bonding during sintering, and achieving rapid densification at a lower temperature.

[0027] In some embodiments, when the sintering temperature is 580°C to 600°C, the holding time ≥8 h; when the temperature is 620°C to 640°C, the constant temperature time ≥1 h.

[0028] In some embodiments, the protective gas is selected from at least one of argon, nitrogen, helium, carbon dioxide, carbon monoxide, and hydrogen, with an oxygen content <1 ppm and a water content <1 ppm.

[0029] The present invention also provides an aluminum powder sintered foil prepared by the above preparation method.

[0030] In some embodiments, the withstand voltage value of the aluminum powder sintered foil ≥615 V, and the specific capacitance ≥0.69 μF / cm 2 。

[0031] The present invention also provides the application of the above aluminum powder sintered foil as an anode material in an aluminum electrolytic capacitor. The aluminum powder sintered foil prepared by the present invention is suitable for the anode of a high specific capacitance aluminum electrolytic capacitor, and can increase the volume specific capacitance by 30% to 50%, providing key technical support for miniaturized and high energy density capacitors.

[0032] The following is a specific description of the content of the present invention through the following examples and comparative examples.

[0033] Example 1 A method for preparing an aluminum powder sintered foil, comprising the following steps: S1. Select an aluminum bright foil with a

[111] crystal plane orientation, a relative texture coefficient of the crystal plane of 95%, and a thickness of the aluminum bright foil of 30 μm; select aluminum powder with a

[111] crystal plane orientation, a relative texture coefficient of the crystal plane of 92%, and a particle size of the aluminum powder of 55 μm.

[0034] S2. Using the above aluminum bright foil and aluminum powder as raw materials, lay the aluminum powder on the surface of the aluminum bright foil, place it in a sintering furnace, and carry out sintering at 600 °C under the protective gas atmosphere of argon, with a heating rate of 5 °C / min, a pressure of 0.5 Mpa, and an insulation time of 8 h. After sintering, cool it to room temperature with the furnace to obtain an aluminum powder sintered foil.

[0035] Example 2 A method for preparing an aluminum powder sintered foil, comprising the following steps: S1. Select an aluminum bright foil with a

[111] crystal plane orientation, a relative texture coefficient of the crystal plane of 91%, and a thickness of the aluminum bright foil of 20 μm; select aluminum powder with a

[200] crystal plane orientation, a relative texture coefficient of the crystal plane of 88%, and a particle size of the aluminum powder of 3 μm.

[0036] S2. Using the above aluminum bright foil and aluminum powder as raw materials, lay the aluminum powder on the surface of the aluminum bright foil, place it in a sintering furnace, and carry out sintering at 620 °C under the protective gas atmosphere of a hydrogen-nitrogen mixture, with a volume ratio of hydrogen to nitrogen of 5:95, a heating rate of 3 °C / min, a pressure of 0.8 Mpa, and an insulation time of 12 h. After sintering, cool it to room temperature with the furnace to obtain an aluminum powder sintered foil.

[0037] Example 3 A method for preparing an aluminum powder sintered foil, comprising the following steps: S1. Select an aluminum bright foil with a

[220] crystal plane orientation, a relative texture coefficient of the crystal plane of 85%, and a thickness of the aluminum bright foil of 40 μm; select aluminum powder with a

[111] crystal plane orientation, a relative texture coefficient of the crystal plane of 93%, and a particle size of the aluminum powder of 8 μm.

[0038] S2. Using the above aluminum bright foil and aluminum powder as raw materials, lay the aluminum powder on the surface of the aluminum bright foil, place it in a sintering furnace, and carry out sintering at 640 °C under the protective gas atmosphere of nitrogen (O2 < 1 ppm), with a heating rate of 10 °C / min, a pressure of 1 Mpa, and an insulation time of 24 h. After sintering, cool it to room temperature with the furnace to obtain an aluminum powder sintered foil.

[0039] Example 4 A method for preparing an aluminum powder sintered foil, comprising the following steps: S1. Select an aluminum foil with a

[111] crystal plane orientation, the relative texture coefficient of the crystal plane is 96%, and the thickness of the aluminum foil is 10 μm; select aluminum powder with a

[111] crystal plane orientation, the relative texture coefficient of the crystal plane is 95%, and the particle size of the aluminum powder is 1 μm.

[0040] S2. Using the above aluminum foil and aluminum powder as raw materials, lay the aluminum powder on the surface of the aluminum foil, place it in a sintering furnace, and sinter it at 580 °C in an atmosphere of protective gas of nitrogen (O2 < 1 ppm), with a heating rate of 0.5 °C / min, a pressure of 0.1 Mpa, and a holding time of 24 h. After sintering, cool it to room temperature with the furnace to obtain an aluminum powder sintered foil.

[0041] Example 5 A preparation method of an aluminum powder sintered foil, comprising the following steps: S1. Select an aluminum foil with a

[111] crystal plane orientation, the relative texture coefficient of the crystal plane is 90%, and the thickness of the aluminum foil is 50 μm; select aluminum powder with a

[311] crystal plane orientation, the relative texture coefficient of the crystal plane is 80%, and the particle size of the aluminum powder is 10 μm.

[0042] S2. Using the above aluminum foil and aluminum powder as raw materials, lay the aluminum powder on the surface of the aluminum foil, place it in a sintering furnace, and sinter it at 640 °C in an atmosphere of protective gas of carbon dioxide (O2 < 1 ppm), with a heating rate of 15 °C / min, a pressure of 1 Mpa, and a holding time of 1 h. After sintering, cool it to room temperature with the furnace to obtain an aluminum powder sintered foil.

[0043] Example 6 A preparation method of an aluminum powder sintered foil, comprising the following steps: S1. Select an aluminum foil with a

[111] crystal plane orientation, the relative texture coefficient of the crystal plane is 93%, and the thickness of the aluminum foil is 25 μm; select aluminum powder with a

[111] crystal plane orientation, the relative texture coefficient of the crystal plane is 90%, and the particle size of the aluminum powder is 4 μm.

[0044] S2. Using the above aluminum foil and aluminum powder as raw materials, lay the aluminum powder on the surface of the aluminum foil, place it in a sintering furnace, and sinter it at 620 °C in an atmosphere of protective gas of carbon monoxide (CO purity ≥ 99.999%, O2 < 0.5 ppm, H2O < 0.5 ppm), with a heating rate of 8 °C / min, a pressure of 0.6 Mpa, and a holding time of 10 h. After sintering, cool it to room temperature with the furnace to obtain an aluminum powder sintered foil.

[0045] Example 7 A preparation method of an aluminum powder sintered foil, comprising the following steps: S1. Select an aluminum foil with a

[111] crystal plane orientation, where the relative texture coefficient of the crystal plane is 94%, and the thickness of the aluminum foil is 15 μm; select aluminum powder with a

[111] crystal plane orientation, where the relative texture coefficient of the crystal plane is 91%, and the particle size of the aluminum powder is 2 μm.

[0046] S2. Using the above aluminum foil and aluminum powder as raw materials, lay the aluminum powder on the surface of the aluminum foil, place it in a sintering furnace, and sinter it at 600 °C in an atmosphere of protective gas of hydrogen (H2 purity ≥ 99.99%, O2 < 0.2 ppm, H2O < 0.2 ppm), with a heating rate of 2 °C / min, a pressure of 0.3 Mpa, and a holding time of 12 h. After sintering, cool it to room temperature with the furnace to obtain an aluminum powder sintered foil.

[0047] Example 8 A method for preparing an aluminum powder sintered foil, comprising the following steps: S1. Select an aluminum foil with a

[111] crystal plane orientation, where the relative texture coefficient of the crystal plane is 92%, and the thickness of the aluminum foil is 35 μm; select aluminum powder with a

[111] crystal plane orientation, where the relative texture coefficient of the crystal plane is 89%, and the particle size of the aluminum powder is 6 μm.

[0048] S2. Using the above aluminum foil and aluminum powder as raw materials, lay the aluminum powder on the surface of the aluminum foil, place it in a sintering furnace, and sinter it at 610 °C in an atmosphere of protective gas of a hydrogen-argon mixture, where the volume ratio of hydrogen to argon is 3:97, with a heating rate of 4 °C / min, a pressure of 0.4 Mpa, and a holding time of 6 h. After sintering, cool it to room temperature with the furnace to obtain an aluminum powder sintered foil.

[0049] Test the performance of the aluminum powder sintered foils prepared in Examples 1 to 8, and the results are shown in Table 1. Table 1 The breakdown voltage and specific capacitance of the aluminum powder sintered foil As shown in Table 1, the breakdown voltage of the aluminum powder sintered foils prepared in Examples 1 to 8 is ≥ 615 V, and the specific capacitance is ≥ 0.69 μF / cm 2 , and the prepared aluminum powder sintered foil is suitable for the anode of high specific capacitance aluminum electrolytic capacitors, can increase the volume specific capacitance by 30% - 50%, and provides key technical support for miniaturized and high energy density capacitors.

[0050] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and modifications.

Claims

1. A method for preparing an aluminum powder sintered foil, characterized in that, It includes the following steps: Using aluminum bright foil and aluminum powder as raw materials, matching the [111] crystal plane orientation of the aluminum bright foil and the aluminum powder, making the relative texture coefficient of the [111] crystal plane of at least one party ≥ 90%, laying the aluminum powder on the surface of the aluminum bright foil, and sintering at 580°C to 640°C under the atmosphere of a protective gas to obtain an aluminum powder sintered foil.

2. The preparation method of the aluminum powder sintered foil according to claim 1, characterized in that The relative texture coefficient of the [111] crystal plane of the aluminum bright foil ≥ 90%, the crystal plane orientation of the aluminum powder is at least one of the [200], [220] or [311] crystal planes, and the relative texture coefficient of the aluminum powder crystal plane ≥ 80%.

3. The preparation method of the aluminum powder sintered foil according to claim 1, characterized in that, The relative texture coefficient of the [111] crystal plane of the aluminum powder is 90%, the crystal plane orientation of the aluminum bright foil is at least one of the [200], [220] or [311] crystal planes, and the relative texture coefficient of the aluminum bright foil crystal plane ≥ 80%.

4. The preparation method of the aluminum powder sintered foil according to claim 1, characterized in that, The thickness of the aluminum bright foil is 10μm to 650μm, and the particle size of the aluminum powder is 1μm to 10μm.

5. The preparation method of the aluminum powder sintered foil according to claim 1, characterized in that, During the sintering process, the heating rate is 0.1°C / min to 15°C / min, the heat preservation time is 1h to 24h, and the pressure is 0.1MPa to 1MPa.

6. The preparation method of the aluminum powder sintered foil according to claim 5, characterized in that, When the sintering temperature is 580°C to 600°C, the heat preservation time ≥ 8h; when the temperature is 620°C to 640°C, the constant temperature time ≥ 1h.

7. The preparation method of the aluminum powder sintered foil according to claim 1, characterized in that, The protective gas is selected from at least one of argon, nitrogen, helium, carbon dioxide, carbon monoxide, and hydrogen, with an oxygen content < 1ppm and a water content < 1ppm.

8. An aluminum powder sintered foil, characterized in that, Prepared by using the preparation method according to any one of claims 1 to 7.

9. The aluminum powder sintered foil according to claim 8, characterized in that, The withstand voltage value of the aluminum powder sintered foil ≥ 615V, and the specific capacitance ≥ 0.69 μF / cm 2 .

10. Application of the aluminum powder sintered foil according to claim 8 as an anode material in an aluminum electrolytic capacitor.

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