An aluminum powder sintered foil and a method of manufacturing and use thereof

Abstract

This invention discloses an aluminum powder sintered foil, its preparation method, and its application, belonging to the field of sintered foil preparation technology. The invention uses aluminum foil and aluminum powder as raw materials, and matches the [111] crystal orientation of the aluminum foil and aluminum powder, ensuring that the relative texture coefficient of the [111] crystal plane of at least one side is ≥90%. Aluminum powder is laid on the surface of the aluminum foil, and sintering is performed at 580℃~640℃ under a protective gas atmosphere to obtain the aluminum powder sintered foil. This invention significantly reduces the interfacial diffusion barrier by controlling the matching of the [111] crystal orientation of the aluminum foil and aluminum powder, achieving low-temperature sintering at 580℃~640℃. This material is suitable for the anode of high-specific-capacitance aluminum electrolytic capacitors, increasing the volumetric specific capacitance by 30%~50%, providing key technical support for miniaturized, high-energy-density capacitors.

Description

Technical Field

[0001] This invention relates to the field of sintered foil preparation technology, specifically to an aluminum powder sintered foil, its preparation method, and its application. Background Technology

[0002] In the field of electronic components, sintered aluminum foil, due to its significantly higher specific capacitance than traditional etched foil, holds promise for applications in aluminum electrolytic capacitors, aiming to substantially increase their volumetric capacitance and energy density while reducing their size and weight. Traditional aluminum powder sintering processes typically employ high-temperature sintering above 600℃. While this achieves material bonding, it suffers from significant drawbacks: 1) High temperatures cause intense diffusion of aluminum atoms, easily leading to coarsening of the sintering neck and reduced porosity, decreasing the flexibility and specific surface area of ​​the aluminum foil; 2) High temperatures increase energy consumption, raising production costs and contradicting the trend of green manufacturing.

[0003] Lowering the sintering temperature is currently a hot research topic and a challenge. 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 overcome it; only by increasing the temperature of the aluminum powder can higher energy be obtained. Therefore, lowering the interfacial barrier is of great significance for achieving low-temperature sintering. Summary of the Invention

[0004] This invention provides an aluminum powder sintered foil, its preparation method and application. In response to the problems of reduced porosity, high energy consumption and poor flexibility caused by traditional high-temperature sintering of aluminum powder (>600℃), this invention significantly reduces the interfacial diffusion barrier by controlling the

[111] crystal orientation of aluminum foil and aluminum powder, and achieves a dual breakthrough of reducing sintering temperature and improving material performance.

[0005] The first objective of this invention is to provide a method for preparing aluminum powder sintered foil, comprising the following steps:

[0006] Using aluminum foil and aluminum powder as raw materials, and matching the

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

[111] crystal plane of at least one of them is ≥90%, aluminum powder is laid on the surface of the aluminum foil, and sintered at 580℃~640℃ in a protective gas atmosphere to obtain aluminum powder sintered foil.

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

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

[200] ,

[220] or

[311] crystal planes, with a relative texture factor of the aluminum powder crystal plane ≥80%.

[0008] As a preferred embodiment, the relative texture factor of the

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

[200] ,

[220] or

[311] crystal planes, with a relative texture factor of the aluminum foil crystal plane ≥80%.

[0009] In 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.

[0010] In a preferred embodiment, during the sintering process, the heating rate is 0.1℃ / min to 15℃ / min, the holding time is 1h to 24h, and the pressure is 0.1MPa to 1MPa.

[0011] As a preferred embodiment, when the sintering temperature is 580℃~600℃, the holding time is ≥8h; when the temperature is 620℃~640℃, the holding time is ≥1h.

[0012] In 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 of <1 ppm and a water content of <1 ppm.

[0013] The second objective of this invention is to provide an aluminum powder sintered foil, which is prepared using the above-described preparation method.

[0014] As a preferred embodiment, the sintered aluminum powder foil has a withstand voltage ≥615V and a specific capacitance ≥0.69μF / cm³. 2 .

[0015] A third objective of this invention is to provide the above-mentioned aluminum powder sintered foil as an anode material in aluminum electrolytic capacitors.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] This invention provides a method for preparing aluminum powder sintered foil. By controlling the

[111] crystal orientation of the aluminum foil and aluminum powder, the interfacial diffusion barrier is significantly reduced, achieving a dual breakthrough of reduced sintering temperature and improved material performance. 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 low activation energy: reducing the atomic migration barrier, so that sintering can be completed at 580℃~640℃; lattice matching: when the crystal orientation of the foil and aluminum powder is consistent, the interfacial defects are reduced and the sintering bonding strength is improved.

[0018] The aluminum powder sintered foil prepared by this invention is suitable for the anode of high specific capacitance aluminum electrolytic capacitors, and can increase the volumetric specific capacitance by 30% to 50%, providing key technical support for miniaturized, high energy density capacitors. Detailed Implementation

[0019] To enable those skilled in the art to better understand and implement the technical solutions of this invention, the invention is further described below with reference to specific embodiments. However, the embodiments are not intended to limit the invention. Unless otherwise specified, the following test methods and detection methods are conventional methods; unless otherwise specified, the reagents and raw materials are commercially available.

[0020] Existing aluminum powder sintering processes typically employ high-temperature sintering above 600℃, which, while achieving material bonding, suffers from significant drawbacks: 1) High temperatures cause intense diffusion of aluminum atoms, easily leading to coarsening of the sintering neck and reduced porosity, decreasing the flexibility and specific surface area of ​​the aluminum foil; 2) High temperatures increase energy consumption, raising production costs and contradicting the trend of green manufacturing. Based on these technical problems, this invention provides an aluminum powder sintered foil, its preparation method, and its applications.

[0021] The technical solution of the present invention will be described in detail below.

[0022] This invention provides a method for preparing aluminum powder sintered foil, comprising the following steps:

[0023] Using aluminum foil and aluminum powder as raw materials, and matching the

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

[111] crystal plane of at least one of them is ≥90%, aluminum powder is laid on the surface of the aluminum foil, and sintered at 580℃~640℃ in a protective gas atmosphere to obtain aluminum powder sintered foil.

[0024] 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℃) of aluminum powder, this invention controls the

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

[111] crystal plane of at least one of the aluminum foil and aluminum powder is ≥90%, which significantly reduces the interfacial diffusion barrier, promotes atomic surface migration, and facilitates the formation of sintering necks during the sintering process, thus achieving a dual breakthrough of reduced sintering temperature and improved material performance.

[0025] In some embodiments, the relative texture factor of the

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

[200] ,

[220] or

[311] crystal planes, with a relative texture factor of the aluminum powder crystal plane ≥80%.

[0026] In some embodiments, the relative texture factor of the

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

[200] ,

[220] or

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

[0027] It should be noted that the aluminum powder selected in this invention has a relative texture coefficient of ≥90% for the

[111] crystal plane, which has high surface activity: its dense atomic arrangement provides more active sites, promoting the adsorption and diffusion of aluminum atoms; it has low activation energy: reducing the atomic migration barrier, so that sintering can be completed at 580℃~640℃; and it has lattice matching: when the orientation of the foil and the aluminum powder crystal plane is consistent, the interface defects are reduced and the sintering bonding strength is improved.

[0028] In some embodiments, 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. It should be noted that, as a preferred embodiment of the present invention, the thickness of the aluminum foil is 10 μm to 650 μm. If the thickness of the aluminum foil is too low, it may fail to support the coating layer formed by the aluminum powder; if the thickness is too high, it may result in poor performance of the sintered aluminum powder foil. As a preferred embodiment 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 prepared sintered aluminum powder foil; if the particle size is too low or too high, it may reduce the porosity, thereby affecting the performance of the sintered aluminum powder foil.

[0029] In some embodiments, during the sintering process, the heating rate is 0.1℃ / min to 15℃ / min, the holding time is 1h to 24h, and the pressure is 0.1MPa to 1MPa. It should be noted that, as a preferred embodiment of the present invention, by sintering at a pressure of 0.1MPa to 1MPa, the performance of the aluminum powder sintered foil is precisely optimized, promoting grain boundary migration and particle bonding during the sintering process, and achieving rapid densification at a lower temperature.

[0030] In some embodiments, when the sintering temperature is 580℃~600℃, the holding time is ≥8h; when the temperature is 620℃~640℃, the holding time is ≥1h.

[0031] 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 of <1 ppm and a water content of <1 ppm.

[0032] The present invention also provides an aluminum powder sintered foil, which is prepared by the above preparation method.

[0033] In some embodiments, the withstand voltage of the sintered aluminum powder foil is ≥615V, and the specific capacitance is ≥0.69μF / cm³. 2 .

[0034] This invention also provides the application of the aforementioned aluminum powder sintered foil as an anode material in aluminum electrolytic capacitors. The aluminum powder sintered foil prepared by this invention is suitable for the anode of high-specific-capacitance aluminum electrolytic capacitors, and can increase the volumetric specific capacitance by 30% to 50%, providing key technical support for miniaturized, high-energy-density capacitors.

[0035] The invention will now be described in detail through the following embodiments and comparative examples.

[0036] Example 1

[0037] A method for preparing aluminum powder sintered foil includes the following steps:

[0038] S1. Select aluminum foil with

[111] crystal orientation, with a relative texture factor of 95% and a thickness of 30 μm; select aluminum powder with

[111] crystal orientation, with a relative texture factor of 92% and a particle size of 55 μm.

[0039] S2. Using the above-mentioned aluminum foil and aluminum powder as raw materials, aluminum powder is laid on the surface of the aluminum foil and placed in a sintering furnace. Under the protective atmosphere of argon, sintering is carried out at 600°C with a heating rate of 5°C / min, a pressure of 0.5 MPa, and a holding time of 8 hours. After sintering, the foil is cooled to room temperature with the furnace to obtain aluminum powder sintered foil.

[0040] Example 2

[0041] A method for preparing aluminum powder sintered foil includes the following steps:

[0042] S1. Select aluminum foil with

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

[200] crystal orientation, with a relative texture coefficient of 88% and a particle size of 3 μm.

[0043] S2. Using the above-mentioned aluminum foil and aluminum powder as raw materials, aluminum powder is laid on the surface of the aluminum foil and placed in a sintering furnace. Under the protective gas atmosphere of hydrogen-nitrogen mixture, the volume ratio of hydrogen to nitrogen is 5:95. Sintering is carried out at 620°C, the heating rate is 3°C / min, the pressure is 0.8 MPa, the holding time is 12h, and after sintering, the foil is cooled to room temperature with the furnace to obtain aluminum powder sintered foil.

[0044] Example 3

[0045] A method for preparing aluminum powder sintered foil includes the following steps:

[0046] S1. Select aluminum foil with

[220] crystal orientation, with a relative texture factor of 85% and a thickness of 40 μm; select aluminum powder with

[111] crystal orientation, with a relative texture factor of 93% and a particle size of 8 μm.

[0047] S2. Using the above-mentioned aluminum foil and aluminum powder as raw materials, aluminum powder is laid on the surface of the aluminum foil and placed in a sintering furnace. Under the protective atmosphere of nitrogen (O2<1ppm), sintering is carried out at 640℃ with a heating rate of 10℃ / min, a pressure of 1MPa, and a holding time of 24h. After sintering, the foil is cooled to room temperature with the furnace to obtain aluminum powder sintered foil.

[0048] Example 4

[0049] A method for preparing aluminum powder sintered foil includes the following steps:

[0050] S1. Select aluminum foil with

[111] crystal orientation, with a relative texture factor of 96% and a thickness of 10 μm; select aluminum powder with

[111] crystal orientation, with a relative texture factor of 95% and a particle size of 1 μm.

[0051] S2. Using the above-mentioned aluminum foil and aluminum powder as raw materials, aluminum powder is laid on the surface of the aluminum foil and placed in a sintering furnace. Under the protective atmosphere of nitrogen (O2<1ppm), sintering is carried out at 580℃ with a heating rate of 0.5℃ / min, a pressure of 0.1Mpa, and a holding time of 24h. After sintering, the foil is cooled to room temperature with the furnace to obtain aluminum powder sintered foil.

[0052] Example 5

[0053] A method for preparing aluminum powder sintered foil includes the following steps:

[0054] S1. Select aluminum foil with

[111] crystal orientation, with a relative texture factor of 90% and a thickness of 50 μm; select aluminum powder with

[311] crystal orientation, with a relative texture factor of 80% and a particle size of 10 μm.

[0055] S2. Using the above-mentioned aluminum foil and aluminum powder as raw materials, aluminum powder is laid on the surface of the aluminum foil and placed in a sintering furnace. Under the protective atmosphere of carbon dioxide (O2<1ppm), sintering is carried out at 640℃ with a heating rate of 15℃ / min, a pressure of 1MPa, and a holding time of 1h. After sintering, the foil is cooled to room temperature with the furnace to obtain aluminum powder sintered foil.

[0056] Example 6

[0057] A method for preparing aluminum powder sintered foil includes the following steps:

[0058] S1. Select aluminum foil with

[111] crystal orientation, with a relative texture factor of 93% and a thickness of 25 μm; select aluminum powder with

[111] crystal orientation, with a relative texture factor of 90% and a particle size of 4 μm.

[0059] S2. Using the above-mentioned aluminum foil and aluminum powder as raw materials, aluminum powder is laid on the surface of the aluminum foil and placed in a sintering furnace. Under the protective atmosphere of carbon monoxide (CO purity ≥ 99.999%, O2 < 0.5 ppm, H2O < 0.5 ppm), sintering is carried out at 620℃ with a heating rate of 8℃ / min, a pressure of 0.6 MPa, and a holding time of 10 h. After sintering, the foil is cooled to room temperature with the furnace to obtain sintered aluminum powder foil.

[0060] Example 7

[0061] A method for preparing aluminum powder sintered foil includes the following steps:

[0062] S1. Select aluminum foil with

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

[111] crystal plane orientation, with a relative texture coefficient of 91% and a particle size of 2μm.

[0063] S2. Using the above-mentioned aluminum foil and aluminum powder as raw materials, aluminum powder is laid on the surface of the aluminum foil and placed in a sintering furnace. Under the protective atmosphere of hydrogen (H2 purity ≥ 99.99%, O2 < 0.2 ppm, H2O < 0.2 ppm), sintering is carried out at 600℃ with a heating rate of 2℃ / min, a pressure of 0.3 MPa, and a holding time of 12 h. After sintering, the foil is cooled to room temperature with the furnace to obtain aluminum powder sintered foil.

[0064] Example 8

[0065] A method for preparing aluminum powder sintered foil includes the following steps:

[0066] S1. Select aluminum foil with

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

[111] crystal orientation, with a relative texture coefficient of 89% and a particle size of 6 μm.

[0067] S2. Using the above-mentioned aluminum foil and aluminum powder as raw materials, aluminum powder is laid on the surface of the aluminum foil and placed in a sintering furnace. Under the protective gas atmosphere of hydrogen-argon mixture, the volume ratio of hydrogen to argon is 3:97. Sintering is carried out at 610°C, the heating rate is 4°C / min, the pressure is 0.4 MPa, the holding time is 6 hours, and after sintering, the foil is cooled to room temperature with the furnace to obtain aluminum powder sintered foil.

[0068] The properties of the aluminum powder sintered foils prepared in Examples 1 to 8 were tested, and the results are shown in Table 1.

[0069] Table 1. Pressure resistance and specific volume of sintered aluminum powder foil

[0070]

[0071] As shown in Table 1, the aluminum powder sintered foils prepared in Examples 1 to 8 have a withstand voltage ≥ 615V and a specific capacitance ≥ 0.69μF / cm³. 2 The prepared aluminum powder sintered foil is suitable for the anode of high specific capacitance aluminum electrolytic capacitors, which can increase the volumetric specific capacitance by 30% to 50%, providing key technical support for miniaturized, high energy density capacitors.

[0072] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing aluminum powder sintered foil, characterized in that, Includes the following steps: Using aluminum foil and aluminum powder as raw materials, and matching the [111] crystal orientation of the aluminum foil and aluminum powder, aluminum powder is laid on the surface of the aluminum foil, and sintered at 580℃~640℃ in a protective gas atmosphere to obtain aluminum powder sintered foil; Among them, the relative texture coefficient of the [111] crystal plane orientation of aluminum foil and aluminum powder is ≥90%; or the relative texture coefficient of the [111] crystal plane of aluminum foil is ≥90%, the crystal plane orientation of aluminum powder is at least one of [200], [220] or [311] crystal plane, and the relative texture coefficient of the aluminum powder crystal plane is ≥80%; or the relative texture coefficient of the [111] crystal plane of aluminum powder is 90%, the crystal plane orientation of aluminum foil is at least one of [200], [220] or [311] crystal plane, and the relative texture coefficient of the aluminum foil crystal plane is ≥80%.

2. The method for preparing aluminum powder sintered foil according to claim 1, characterized in that, The thickness of the aluminum foil ranges from 10 μm to 650 μm, and the particle size of the aluminum powder ranges from 1 μm to 10 μm.

3. The method for preparing aluminum powder sintered foil according to claim 1, characterized in that, During the sintering process, the heating rate is 0.1℃ / min to 15℃ / min, the holding time is 1h to 24h, and the pressure is 0.1MPa to 1MPa.

4. The method for preparing aluminum powder sintered foil according to claim 3, characterized in that, When the sintering temperature is 580℃~600℃, the holding time is ≥8h; when the temperature is 620℃~640℃, the holding time is ≥1h.

5. The method for preparing 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 of <1 ppm and a water content of <1 ppm.

6. A sintered aluminum powder foil, characterized in that, It is prepared by any one of the preparation methods of claims 1 to 5.

7. The aluminum powder sintered foil according to claim 6, characterized in that, The withstand voltage of the sintered aluminum powder foil is ≥615V, and the specific capacitance is ≥0.69μF / cm³. 2 .

8. The application of the aluminum powder sintered foil as described in claim 6 as an anode material in an aluminum electrolytic capacitor.

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