Method for producing sintered aluminum foil and production apparatus

Abstract

A preparation method of sintered aluminum foil, comprising the following steps: 1) cleaning; the light foil is cleaned with acid on the surface, then washed clean with deionized water and dried; 2) slurry forming; a layer of aluminum powder or aluminum alloy powder slurry is formed on the light foil treated in step 1), and dried and solidified; 3) slurry compaction; the slurry completed in step 2) is compacted, and the compaction pressure is 1.5-2.5 atmospheres; 4) sintering; the aluminum foil completed in step 3) is put into a sintering furnace for sintering, including pretreatment, sintering treatment and annealing treatment; the pretreatment decomposes the binder in the aluminum powder or aluminum alloy powder slurry after solidification; the sintering treatment compacts the aluminum powder or aluminum alloy powder on the light foil before sintering treatment; the aluminum foil is in S shape or snake shape at the end of sintering treatment; the annealing treatment. The preparation method of sintered aluminum foil and the production equipment can realize the industrialized production of sintered aluminum, and the produced aluminum foil has good tensile strength, and the aluminum foil can be coiled.

Description

Technical Field

[0001] This invention relates to an aluminum foil production apparatus, and more particularly to a method for preparing sintered aluminum foil and production equipment. Background Technology

[0002] Currently, the anode foil used in aluminum electrolytic capacitors is etched foil. Etching increases the surface area of ​​the aluminum foil by etching it with acid. However, there are limitations to increasing the surface area using acid etching, and because etched foil is formed by acid etching, its strength is low and it is easily broken. Furthermore, the acids used in its production have a significant environmental impact. To replace etched foil and further improve the anode foil for aluminum electrolytic capacitors, sintered foil, also known as deposited foil, has emerged. Sintered foil is made by bonding nano- or micron-sized aluminum powder to a base foil through sintering. The base foil is typically a smooth foil without an oxide film on its surface.

[0003] Because sintered foils use nano- or micron-sized aluminum powder, which is highly reactive, the sintering process requires very strict control. Currently, sintered foils in China are all sintered under laboratory conditions, and there are no continuous sintering furnaces suitable for industrial production. Furthermore, the sintering methods under laboratory conditions differ from those used in continuous industrial production. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method and equipment for preparing sintered aluminum foil suitable for continuous production.

[0005] To solve the above-mentioned technical problems, the technical solution proposed by this invention is: a method for preparing sintered aluminum foil, comprising the following steps:

[0006] 1) Cleaning; Clean the surface of the foil with acid, then rinse it with deionized water and dry it;

[0007] 2) Slurry forming; A layer of aluminum powder or aluminum alloy powder slurry is formed on the foil after step 1), and then dried and cured;

[0008] 3) Compacting the slurry; compact the slurry after step 2) at a pressure of 1.5-2.5 atmospheres;

[0009] 4) Sintering; The aluminum foil that has completed step 3) is placed into a sintering furnace for sintering, including pretreatment, sintering and annealing.

[0010] Pretreatment decomposes the binder in the cured aluminum powder or aluminum alloy powder slurry;

[0011] Sintering process: aluminum powder or aluminum alloy powder is compacted on the foil before sintering; at the end of the sintering process, the aluminum foil is arranged in an S-shape; the sintering temperature is 550℃-660℃.

[0012] Annealing treatment, the annealing temperature is controlled at 400℃-550℃, and the aluminum foil is S-shaped at the front end of the annealing process;

[0013] In the above-mentioned method for preparing sintered aluminum foil, preferably, the sintering in step 4) is protected by nitrogen gas, and the sintering furnace is filled with nitrogen gas to ensure that nitrogen gas overflows from the sintering furnace.

[0014] In the above-mentioned method for preparing sintered aluminum foil, preferably, the pretreatment temperature is distributed in an ascending manner, and the pretreatment process includes at least one compaction treatment of the aluminum powder or aluminum alloy powder on the foil, with a compaction pressure of 1.5-2.5 atmospheres.

[0015] In the above-described method for preparing sintered aluminum foil, preferably, the sintering process includes three stages.

[0016] Phase 1: Temperature rises to 400℃-500℃.

[0017] Phase Two: Temperature rises to 500℃-660℃

[0018] The third stage: the temperature gradually decreases to 400℃-550℃.

[0019] A production equipment for sintering aluminum foil includes a cleaning tank, a slurry forming device, a first compaction device, and a sintering furnace connected in sequence. The sintering furnace includes a heat preservation component, a transmission component, and a heating component. The heating component is installed on the inner wall of the heat preservation component, which forms a furnace chamber with openings at both ends. The transmission component is disposed inside the furnace chamber and includes multiple rollers. A first bearing and a second bearing are respectively installed at both ends of the rollers. A transmission gear is installed at the end of the roller with the second bearing, and the transmission gear rotates synchronously. The sintering furnace is divided into at least three temperature zones: a first temperature zone, a second temperature zone, and a third temperature zone. The rollers at the junction of the second and third temperature zones are staggered. A second compaction device is provided in the first or second temperature zone.

[0020] In the aforementioned production equipment for sintered aluminum foil, preferably, the second bearing is installed inside the insulation component, one end of the roller on which the second bearing is installed extends out of the insulation component, and the transmission gear is installed at the part of the roller that extends out of the insulation component.

[0021] In the aforementioned production equipment for sintered aluminum foil, preferably, the insulation component comprises, from the outside to the inside, an insulation layer, refractory bricks, and an inner wall of the furnace. The inner wall of the furnace is made of stainless steel or refractory coating, and the heating component is installed on the refractory bricks.

[0022] In the aforementioned production equipment for sintered aluminum foil, preferably, the heat insulation component forms a furnace body and a furnace cover. One side of the furnace cover is hinged to the furnace body, and the other side is connected to a lifting device. The lifting device includes a lifting rope and a lifting cover rotating shaft. One end of the lifting rope is connected to the lifting cover rotating shaft, and the other end can be connected to one side of the furnace cover. The lifting cover rotating shaft is fixedly installed above the furnace cover.

[0023] Preferably, in the above-mentioned production equipment for sintered aluminum foil, the slurry forming device includes a slurry application component, a leveling component, and a drying component connected in sequence. The leveling component includes a scraper and a support, and the scraper is arranged at a preset angle to the forward direction of the aluminum foil.

[0024] Preferably, in the above-mentioned production equipment for sintered aluminum foil, both the first compaction device and the second compaction device include an upper compaction roller, a lower compaction roller, a pressure assembly, and a support; the lower compaction roller is connected to the support via a bearing, the upper compaction roller is connected to the pressure assembly via a bearing, and the pressure assembly is connected to the support; the pressure assembly includes a support rod and a pressure spring passing through the support rod; the upper compaction roller and the lower compaction roller are arranged opposite to each other.

[0025] Compared with the prior art, the advantages of the present invention are: the preparation method and production equipment of the sintered aluminum foil of the present invention can realize the industrial production of sintered aluminum, and the produced aluminum foil has good tensile strength and can be rolled up. Attached Figure Description

[0026] Figure 1 This is a flowchart of the production equipment for sintering aluminum foil in Example 1.

[0027] Figure 2 This is a cross-sectional view of the sintering furnace in Example 1.

[0028] Figure 3 This is a schematic diagram of the lifting device in Example 1.

[0029] Figure 4 This is a schematic diagram of the structure of the first compaction device or the second compaction device.

[0030] Figure 5 This is a layout diagram of the rollers inside the sintering furnace in Example 1.

[0031] 1. Cleaning tank; 2. Slurry forming device; 3. First compaction device; 31. Upper compaction roller; 32. Lower compaction roller; 33. Support rod; 34. Pressure spring; 35. Support rod; 36. Bracket; 4. Sintering furnace; 41. Insulation component; 411. Insulation layer; 412. Refractory brick; 413. Furnace inner wall; 42. Transmission component; 421. Roller; 422. First bearing; 423. Second bearing; 424. Transmission gear; 43. Heating component; 44. Furnace cover; 45. Furnace body; 5. Second compaction device; 6. Lifting device; 61. Lifting rope; 62. Lifting cover rotating shaft. Detailed Implementation

[0032] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0033] It should be noted that when a component is described as being "fixed to, attached to, connected to or connected to" another component, it can be directly fixed to, attached to, connected to or connected to the other component, or it can be indirectly fixed to, attached to, connected to or connected to the other component through other intermediate connectors.

[0034] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention. Example 1

[0035] A method for preparing sintered aluminum foil includes the following steps: cleaning, slurry forming, slurry compaction, and sintering.

[0036] 1) Cleaning: Clean the surface of the foil with acid, then rinse it with deionized water and dry it.

[0037] In this embodiment, the foil refers to uncorroded aluminum foil, and its thickness is generally 20-500 μm. The acid used to clean the foil is generally an organic acid or a low-concentration hydrochloric acid. After removing the oxide film on the foil surface with hydrochloric acid or organic acid, it is rinsed clean with deionized water.

[0038] 2) Slurry forming: A layer of aluminum powder or aluminum alloy powder slurry is formed on the foil after step 1), and then dried and cured.

[0039] The aluminum powder or aluminum alloy powder slurry includes nano- or micron-sized aluminum powder or aluminum alloy powder and a binder. The micron-sized aluminum powder or aluminum alloy powder has a size of less than 10 micrometers. The binder includes a solvent, an adhesive, and additives. The solvent can be one or more of ethanol, ethylene glycol, NMP, acetone, and lipid organic solvents. The slurry includes an adhesive, and the weight ratio of aluminum powder or aluminum alloy powder to solvent can be between 1:1 and 2.5:1, depending on actual needs. The adhesive can be one or more of polyvinylidene fluoride, polyester resin, epoxy resin, and phenolic resin. If necessary, a surfactant can be added to the slurry. The surfactant can be one or more of polypropylene, 2-oxalone, polyethylene glycol, and ethylene-acrylic acid copolymer.

[0040] The slurry can be applied to the foil after step 1) by means of slurry application or coating. The thickness of the slurry layer is between 20-500 μm. After the slurry layer is formed, it is leveled with a scraper to make the slurry thickness on the foil basically uniform. After the slurry is leveled, it is heated to cure.

[0041] 3) Compacting the slurry; compact the slurry after completing step 2).

[0042] The slurry is compacted using a first compaction device. In this embodiment, 3-6 first compaction devices are arranged side by side during compaction, meaning that the slurry undergoes 3-6 compaction passes before sintering. The compaction pressure is 1.5-2.5 atmospheres, preferably around 2 atmospheres.

[0043] 4) Sintering; The aluminum foil that has completed step 3) is placed into a sintering furnace for sintering, including pretreatment, sintering treatment and annealing treatment.

[0044] Pretreatment decomposes the binder in the cured aluminum powder or aluminum alloy powder slurry. During pretreatment, the temperature rises gradually. At the end of the pretreatment process, at least one compaction treatment is performed on the aluminum powder or aluminum alloy powder on the foil, with a compaction pressure of 1.5-2.5 atmospheres; preferably around 2 atmospheres. A second compaction device is used, with the same structure as the first, except that the second device needs to be heat-resistant. Compaction can also be performed at the beginning of the sintering process.

[0045] The sintering process involves compacting aluminum powder or aluminum alloy powder onto a light foil before sintering. At the end of the sintering process, the aluminum foil is positioned in an S-shape. The sintering temperature is 550℃-660℃. The sintering process includes three stages corresponding to the first, second, and third temperature zones. The first stage involves raising the temperature to 400℃-500℃; the second stage involves raising the temperature to 500℃-660℃; and the third stage involves gradually decreasing the temperature to 400℃-550℃ for approximately 5 minutes. The combined time for the first and second stages is approximately 6-7 hours. In this embodiment, the aluminum powder or aluminum alloy powder is not melted and bonded during sintering, but rather molecular exchange occurs between adjacent aluminum powder or aluminum alloy powder under high temperature conditions, causing them to bond together. To ensure contact between adjacent aluminum powder or aluminum alloy powder during sintering, the aluminum powder or aluminum alloy powder on the aluminum foil needs to be compacted during pretreatment.

[0046] Annealing is performed at a temperature controlled between 400℃ and 550℃, with the aluminum foil exhibiting an S-shaped movement at the front end of the annealing process.

[0047] Step 4) sintering is protected by nitrogen. The sintering furnace is filled with nitrogen to ensure nitrogen overflow. Because the sintering furnace has openings at both ends, it is not completely sealed and cannot be completely free of oxygen. However, the amount and rate of nitrogen injection must ensure that the oxygen volume content inside the sintering furnace is below 2%. The openings at both ends of the sintering furnace are the aluminum foil inlet and the aluminum foil outlet, respectively. In this embodiment, nitrogen enters the sintering furnace from the outlet end.

[0048] At the end of the sintering process and the beginning of the annealing process, the aluminum foil moves in an S-shape, meaning the rollers are staggered at the junction of the second and third temperature zones during sintering. During this process, the aluminum foil is relatively soft, and the S-shaped movement enhances its strength after sintering, ensuring it can be wound into rolls. However, if the aluminum foil is too thick, such as when the thickness of the foil plus aluminum powder or aluminum alloy powder exceeds 300μm, the S-shaped movement is unnecessary because the excessive thickness makes it unsuitable for winding.

[0049] A production device for sintering aluminum foil includes a cleaning tank 1, a slurry forming device 2, a first compaction device 3, and a sintering furnace 4 connected in sequence. Figure 1The diagram shows a flowchart of the production equipment for sintering aluminum foil in this embodiment. The sintering furnace 4 includes a heat preservation component 41, a transmission component 42, and a heating component 43. The heating component 43 is installed on the inner wall of the heat preservation component 41 and is a heating silicon carbide rod. The heat preservation component 41 forms a furnace chamber with openings at both ends in the middle. The transmission component 42 is disposed inside the furnace chamber and includes multiple rollers 421 made of stainless steel. A first bearing 422 and a second bearing 423 are respectively installed at both ends of the rollers 421. A transmission gear 424 is installed at the end of the roller 421 where the second bearing 423 is installed, and the transmission gear 424 rotates synchronously. The sintering furnace 4 is divided into at least three temperature zones: a first temperature zone, a second temperature zone, and a third temperature zone. These three temperature zones correspond to the first, second, and third stages of the aforementioned preparation method, respectively. Figure 5 The rollers 421 at the junction of the second and third temperature zones are staggered; a second compaction device 5 is provided in the first or second temperature zone. Figure 2 This is a cross-sectional structural diagram of sintering furnace 4.

[0050] like Figure 2 As shown, in this embodiment, the second bearing 423 is installed inside the insulation component 41, and one end of the roller 421 on which the second bearing 423 is installed extends out of the insulation component 41. The transmission gear 424 is installed on the part of the roller 421 that extends out of the insulation component 41. The insulation component 41 includes, from the outside to the inside, an insulation layer 411, refractory bricks 412, and a furnace inner wall 413. The furnace inner wall 413 is made of stainless steel or refractory coating, and the heating component 43 is installed on the refractory bricks 412.

[0051] like Figure 2 and Figure 3 As shown, the heat insulation component 41 forms the furnace body 45 and the furnace cover 44. One side of the furnace cover 44 is hinged to the furnace body 45, and the other side is connected to a lifting device 6. The lifting device 6 includes a lifting rope 61 and a lifting cover rotation shaft 62. One end of the lifting rope 61 is connected to the lifting cover rotation shaft 62, and the other end can be connected to one side of the furnace cover 44. The lifting cover rotation shaft 62 is fixedly installed above the furnace cover 44.

[0052] In this embodiment, the slurry forming device 2 includes a slurry application component, a leveling component, and a drying component connected in sequence. In this embodiment, the slurry application component includes a slurry coating component, which can be a traditional slurry coating device. The leveling component is as follows: Figure 5 As shown, it includes a scraper and a support 36. The scraper is at a certain angle to the forward direction of the aluminum foil, and the angle can be between 15 and 75 degrees.

[0053] In this embodiment, as Figure 4As shown, the first compaction device 3 includes an upper compaction roller 31, a lower compaction roller 32, a pressure assembly, and a support 36. The lower compaction roller 32 is connected to the support 36 via bearings, and the upper compaction roller 31 is connected to the pressure assembly via bearings. The pressure assembly is connected to the support 36. The pressure assembly includes a support rod 33 and a pressure spring 34 passing through the support rod 33. The upper compaction roller 31 and the lower compaction roller 32 are arranged opposite to each other. The structure of the second compaction device 5 is the same as that of the first compaction device 3. The difference between the second compaction device 5 and the first compaction device 3 is that the second compaction device 5 is heat-resistant, while the first compaction device 3 is not.

[0054] The preparation method and production equipment of sintered aluminum foil in this embodiment can realize the industrial production of sintered aluminum, and the produced aluminum foil has good tensile strength and can be rolled up.

Claims

1. A method for preparing sintered aluminum foil, characterized in that, Includes the following steps: 1) Cleaning; Clean the surface of the foil with acid, then rinse it with deionized water and dry it; 2) Slurry forming; A layer of aluminum powder or aluminum alloy powder slurry is formed on the foil after step 1), and then dried and cured; 3) Compacting the slurry; compact the slurry after step 2) at a pressure of 1.5-2.5 atmospheres; 4) Sintering; The aluminum foil that has completed step 3) is placed into a sintering furnace for sintering, including pretreatment, sintering and annealing. Pretreatment decomposes the binder in the cured aluminum powder or aluminum alloy powder slurry; the temperature of the pretreatment is distributed in an ascending manner, and the pretreatment process includes at least one compaction treatment of the aluminum powder or aluminum alloy powder on the foil, with a compaction pressure of 1.5-2.5 atmospheres; Sintering process: aluminum powder or aluminum alloy powder is compacted on the foil before sintering; at the end of the sintering process, the aluminum foil is arranged in an S-shape; the sintering temperature is 550℃-660℃. Annealing is performed at a temperature controlled between 400℃ and 550℃, with the aluminum foil exhibiting an S-shaped movement at the front end of the annealing process.

2. The method for preparing sintered aluminum foil according to claim 1, characterized in that: The sintering in step 4) is protected by nitrogen gas, and the sintering furnace is filled with nitrogen gas to ensure that nitrogen gas overflows from the sintering furnace.

3. The method for preparing sintered aluminum foil according to claim 1, characterized in that: The sintering process includes three stages. The first stage involves raising the temperature to 400℃-500℃. Phase Two: Temperature rises to 500℃-660℃ The third stage: the temperature gradually decreases to 400℃-550℃.

4. A production apparatus for implementing the method for preparing sintered aluminum foil according to any one of claims 1-3, characterized in that: The sintering furnace comprises a washing tank, a slurry forming device, a first compaction device, and a sintering furnace connected in sequence. The sintering furnace includes a heat preservation component, a transmission component, and a heating component. The heating component is installed on the inner wall of the heat preservation component, which forms a furnace chamber with openings at both ends. The transmission component is disposed within the furnace chamber and includes multiple rollers. A first bearing and a second bearing are respectively installed at both ends of each roller. A transmission gear is installed at the end of each roller with the second bearing, and the transmission gear rotates synchronously. The sintering furnace is divided into at least three temperature zones: a first temperature zone, a second temperature zone, and a third temperature zone. The rollers at the junction of the second and third temperature zones are staggered. A second compaction device is provided within the first or second temperature zone.

5. The production equipment according to claim 4, characterized in that: The second bearing is installed inside the insulation component, and one end of the roller on which the second bearing is installed extends out of the insulation component. The transmission gear is installed on the part of the roller that extends out of the insulation component.

6. The production equipment according to claim 4, characterized in that: The insulation component comprises, from the outside to the inside, an insulation layer, refractory bricks, and an inner wall of the furnace. The inner wall of the furnace is made of stainless steel or refractory coating, and the heating component is installed on the refractory bricks.

7. The production equipment according to claim 4, characterized in that: The heat insulation component forms the furnace body and the furnace cover. One side of the furnace cover is hinged to the furnace body, and the other side is connected to a lifting device. The lifting device includes a lifting rope and a lifting cover rotating shaft. One end of the lifting rope is connected to the lifting cover rotating shaft, and the other end can be connected to one side of the furnace cover. The lifting cover rotating shaft is fixedly installed above the furnace cover.

8. The production equipment according to claim 4, characterized in that: The slurry forming device includes a slurry application component, a leveling component, and a drying component connected in sequence. The leveling component includes a scraper and a support, and the scraper is arranged at a preset angle to the forward direction of the aluminum foil.

9. The production equipment according to claim 4, characterized in that: Both the first compaction device and the second compaction device include an upper compaction roller, a lower compaction roller, a pressure component, and a support; the lower compaction roller is connected to the support via a bearing, the upper compaction roller is connected to the pressure component via a bearing, and the pressure component is connected to the support; the pressure component includes a support rod and a pressure spring passing through the support rod; the upper compaction roller and the lower compaction roller are arranged opposite to each other.

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