A method for treating pore-forming corrosion of an etched foil and its application

Abstract

The present invention provides a method for treating pore-forming corrosion for preparing etched foils and its application. The method for pore-forming corrosion includes the following steps: S1. Putting the pretreated aluminum foil into a pore-forming solution for first-stage pore formation and applying a first decaying current; S2. When the current density decays to 10-20% of i0, disconnecting the current and putting the aluminum foil into an intermediate treatment solution for intermediate treatment; S3. Putting the aluminum foil after intermediate treatment into the pore-forming solution for second-stage pore formation and applying a second decaying current, and the current density of the initial current is 10-20% of i0; S4. Repeating S1.-S3. for the treated aluminum foil in sequence, and the number of repetitions is at least 3 times; wherein, the intermediate treatment solution is a solution containing 1 wt-5 wt% of phosphoric acid and 0.005 wt-0.06 wt% of an additive. The treatment method can improve the blockage of ineffective pores in the subsequent etching process, reduce the number of short holes, and the prepared etched foil has high specific capacitance, tensile strength and bending performance, and at the same time, the pore uniformity of the etched foil is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of pore-forming corrosion of etched foils, and particularly relates to a treatment method for pore-forming corrosion of preparing etched foils and its application. Background Art

[0002] Etched foil is a key raw material for manufacturing aluminum electrolytic capacitors. Conventional etched foil manufacturing processes mainly include pretreatment, multi-stage pore-forming corrosion, reaming corrosion, post-treatment and other processes. In the prior art, pretreatment can effectively remove oil stains, impurities and natural oxide films on the surface of aluminum foil. However, in the conventional pore-forming process, there will be ineffective pore formation due to the pores not growing continuously or not growing completely.

[0003] These ineffective pores will cause pore blockage in subsequent applications, resulting in a low specific capacitance of the etched foil. At the same time, the ineffective pores may also cause the generation of short pores, affecting the uniformity of the etched pores. Therefore, it is necessary to provide a new treatment method for pore-forming corrosion of preparing etched foils to reduce ineffective pore formation and improve the uniformity, specific capacitance, tensile strength, bending strength and other properties of the etched pores. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a treatment method for pore-forming corrosion of preparing etched foils. For the aluminum foil after the first-stage pore formation, medium treatment is carried out with a medium treatment solution containing phosphoric acid and additives, which can improve the blockage of ineffective pores in the subsequent corrosion process, reduce the number of short pores, and the prepared etched foil has a high specific capacitance, tensile strength and bending properties. At the same time, the uniformity of the pores of the etched foil is improved.

[0005] To achieve the above purpose, the present invention is realized through the following technical solutions:

[0006] A treatment method for pore-forming corrosion of preparing etched foils includes the following steps:

[0007] S1. Put the pretreated aluminum foil into a pore-forming solution for the first-stage pore formation, and apply a first decaying current, and the current density of the initial current is i0;

[0008] S2. When the current density decays to 10-20% of i0, disconnect the current, and put the aluminum foil into the medium treatment solution for medium treatment;

[0009] S3. Put the medium-treated aluminum foil into a pore-forming solution for the second-stage pore formation, and apply a second decaying current. The current density of the initial current of the second decaying current is 10-20% of i0, and the pore formation is completed when the current density decays to 2-8% of i0;

[0010] S4. Repeat S1.-S3. for the treated aluminum foil in sequence, and the number of repetitions is at least 3 times;

[0011] Among them, the intermediate treatment liquid is a solution containing 1 wt% to 5 wt% of phosphoric acid and 0.005 wt% to 0.06 wt% of an additive; the additive is one or more of polyethylene glycol, sodium dodecylbenzenesulfonate or polyphosphoric acid.

[0012] In the above solution, during the pore-forming process, when the current density decays to 10% to 20% of the initial current, an intermediate treatment is carried out using a solution containing phosphoric acid and an additive, so that an oxide film can be formed on the surface of the aluminum foil while adsorbing the additive to generate a polymer film, and the polymer film can increase the energy required for pore formation; during the second-stage pore formation, the applied current cannot generate new pores, thereby reducing the generation of ineffective pores, which helps to increase the specific volume. At the same time, during the second-stage pore formation, the applied current can be used for the growth of the already formed pores to improve the uniformity of the corrosion pores.

[0013] In the present invention, i0 can be selected for the pore-forming corrosion of the etched foil according to the prior art. Preferably, i0 is 1.2 to 1.8 A / cm 2 。

[0014] In the present invention, the current density of the first decaying current decays to 10% to 20% of i0 within 8 to 16 s; the current density of the second decaying current decays to 2% to 8% of i0 within 2 to 10 s.

[0015] Specifically, the first decaying current is: the current density of the initial current is 1.2 to 1.8 A / cm 2 and decays to 0.12 to 0.36 A / cm within 8 to 16 s 2 。

[0016] The second decaying current is: the current density of the initial current is 0.12 to 0.36 A / cm 2 and decays to 0.04 to 0.1 A / cm within 2 to 10 s 2 。

[0017] Preferably, the pore-forming solution is a mixed solution containing 35 wt% to 45 wt% sulfuric acid, 7 wt% to 9 wt% hydrochloric acid and 0.4 wt% to 0.6 wt% aluminum ions.

[0018] Preferably, the temperature of the pore-forming solution is 65 to 75 °C.

[0019] Preferably, the intermediate treatment liquid is a solution containing 1 wt% to 5 wt% of phosphoric acid and 0.03 wt% to 0.05 wt% of an additive.

[0020] More preferably, the intermediate treatment liquid is a solution of 3 wt% to 4 wt% phosphoric acid and 0.03 wt% to 0.05 wt% of an additive.

[0021] Preferably, the time for the medium treatment is 20 to 60 s.

[0022] Preferably, the temperature for the medium treatment is 60 to 85 °C.

[0023] Preferably, in step S1., the pretreatment is one of alkali treatment, phosphoric acid solution treatment or hydrochloric acid solution treatment.

[0024] Another object of the present invention is to provide a porous aluminum foil.

[0025] Another object of the present invention is to provide a method for preparing an etched foil.

[0026] A method for preparing an etched foil includes the following steps: subjecting the porous aluminum foil obtained by the above method to hole expansion etching, post-treatment, and drying treatment in sequence.

[0027] Specifically, the method for preparing the etched foil includes the following steps:

[0028] S11. Treating an aluminum foil by using the hole expansion etching treatment method to obtain a porous aluminum foil;

[0029] S12. Placing the porous aluminum foil into a hole expansion solution for electroetching to obtain a hole-expanded aluminum foil;

[0030] S13. Placing the hole-expanded aluminum foil into a nitric acid solution containing aluminum for treatment for 50 to 70 s, washing, and drying.

[0031] In the present invention, a hole expansion solution can be selected with reference to the existing art method for preparing an etched foil. Preferably, in step S12., the hole expansion solution is a mixed solution containing 6 wt to 10 wt% of nitric acid and 0.6 wt to 0.8 wt% of aluminum ions.

[0032] In the present invention, the temperature range of the hole expansion solution can be selected with reference to the existing art method for preparing an etched foil. Preferably, in step S12., the temperature of the hole expansion solution is 65 to 75 °C.

[0033] In the present invention, the current density of electroetching can be selected with reference to the existing art method for preparing an etched foil. Preferably, in step S12., the current density of electroetching is 0.1 to 0.2 A / cm 2 。

[0034] In the present invention, the time of electroetching can be selected with reference to the existing art method for preparing an etched foil. Preferably, in step S12., the time of electroetching is 450 to 650 s.

[0035] Preferably, in step S14, the aluminum-containing nitric acid solution is a mixed solution of 4.5 wt% to 5.5 wt% nitric acid and 0.3 wt% to 0.5 wt% aluminum ions.

[0036] An etched foil is prepared by the above method.

[0037] Another object of the present invention is to provide a method for preparing an anode foil.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The present invention provides a method for treating the pore-forming corrosion of an etched foil. In the first-stage pore formation of the present invention, a decaying current is used. When the current decays to 10% to 20% of the initial current, after power-off, a solution containing phosphoric acid and an additive is used for intermediate treatment. After the intermediate treatment, a smaller current is applied for the second-stage pore formation. The etched foil prepared by using the pore-forming corrosion treatment method of the present invention has better specific capacitance, tensile strength and bending performance, and can effectively reduce the number of short holes and improve the uniformity of corrosion holes. Description of the Drawings

[0040] Figure 1 It is a cross-sectional morphology diagram of the etched foil prepared after the pore-forming corrosion treatment method of Example 1;

[0041] Figure 2 It is a cross-sectional morphology diagram of the etched foil prepared after the pore-forming corrosion treatment method of Comparative Example 1. Detailed Embodiments

[0042] The following further elaborates the present invention in detail with reference to specific embodiments. The embodiments are only used to explain the present invention and are not used to limit the scope of the present invention. The test methods used in the following embodiments are all conventional methods unless otherwise specified; the materials, reagents, etc. used are all reagents and materials that can be obtained from commercial channels unless otherwise specified.

[0043] The aluminum foil used in the examples: the thickness is 130 μm, the model: L9090503-01-01-03, purchased from Dongyangguang Precision Foil Co., Ltd.; the sodium hydroxide, sulfuric acid, nitric acid, phosphoric acid, polyethylene glycol, hydrochloric acid used are all commercially available.

[0044] Example 1

[0045] A method for treating the pore-forming corrosion of an etched foil, including the following steps:

[0046] S1. The aluminum foil is put into a solution containing 5 wt% sodium hydroxide for pretreatment. The pretreatment time is 40 s, and the pretreatment temperature is 60 °C;

[0047] S2. Place the pretreated aluminum foil into a mixed solution containing 40 wt% sulfuric acid, 8 wt% nitric acid, and 0.5 wt% aluminum ions for the first-stage pore formation, and apply a first decaying current; the current density of the initial current of the first decaying current is 1.5 A / cm 2 , decaying to 0.3 A / cm within 12 s 2 ;

[0048] S3. Disconnect the current, and perform intermediate treatment with a solution containing 2 wt% phosphoric acid and 0.05 wt% polyethylene glycol. The time for intermediate treatment is 40 s, and the temperature for intermediate treatment is 60 °C;

[0049] S3. Continue to apply electricity to the aluminum foil after intermediate treatment for the second-stage pore formation, and apply a second decaying current; the current density of the initial current of the second decaying current is 0.3 A / cm 2 , decaying to 0.08 A / cm within 6 s 2 Complete the pore formation;

[0050] S4. Sequentially repeat S1. to S3. for the treated aluminum foil, and repeat 4 times to obtain the pore-formed aluminum foil.

[0051] Example 2

[0052] A method for treating pore-forming corrosion of preparing etched foil, comprising the following steps:

[0053] S1. Place the aluminum foil into a solution containing 20 wt% hydrochloric acid for pretreatment. The pretreatment time is 60 s, and the pretreatment temperature is 75 °C;

[0054] S2. Place the pretreated aluminum foil into a mixed solution containing 40 wt% sulfuric acid, 8 wt% nitric acid, and 0.5 wt% aluminum ions for the first-stage pore formation, and apply a first decaying current; the current density of the initial current of the first decaying current is 1.6 A / cm 2 , decaying to 0.16 A / cm within 14 s 2 ;

[0055] S3. Disconnect the current, and perform intermediate treatment with a solution containing 4 wt% phosphoric acid and 0.03 wt% polyethylene glycol. The time for intermediate treatment is 30 s, and the temperature for intermediate treatment is 80 °C;

[0056] S3. Continue to apply electricity to the aluminum foil after intermediate treatment for the second-stage pore formation, and apply a second decaying current; the current density of the initial current of the second decaying current is 0.16 A / cm 2 , decaying to 0.04 A / cm within 10 s 2 Complete the pore formation;

[0057] S4. Repeat the steps of S1. to S3. successively on the processed aluminum foil for 4 times to obtain the porous aluminum foil.

[0058] Example 3

[0059] The steps and parameters are the same as those in Example 1, except that the intermediate treatment is carried out using a solution containing 2 wt% of phosphoric acid and 0.06 wt% of polyethylene glycol.

[0060] Example 4

[0061] The steps and parameters are the same as those in Example 1, except that the intermediate treatment is carried out using a solution containing 2 wt% of phosphoric acid and 0.005 wt% of polyethylene glycol.

[0062] Example 5

[0063] The steps and parameters are the same as those in Example 1, except that the intermediate treatment is carried out using a solution containing 2 wt% of phosphoric acid and 0.03 wt% of polyethylene glycol.

[0064] Example 6

[0065] The steps and parameters are the same as those in Example 1, except that the intermediate treatment is carried out using a solution containing 1 wt% of phosphoric acid and 0.05 wt% of polyethylene glycol.

[0066] Example 7

[0067] The steps and parameters are the same as those in Example 1, except that the intermediate treatment is carried out using a solution containing 5 wt% of phosphoric acid and 0.05 wt% of polyethylene glycol.

[0068] Example 8

[0069] The steps and parameters are the same as those in Example 1, except that the intermediate treatment is carried out using a solution containing 4 wt% of phosphoric acid and 0.05 wt% of polyethylene glycol.

[0070] Example 9

[0071] The steps and parameters are the same as those in Example 1, except that the temperature of the intermediate treatment is 85 °C.

[0072] Example 10

[0073] The steps and parameters are the same as those in Example 1, except that the temperature of the intermediate treatment is 50 °C.

[0074] Example 11

[0075] The steps and parameters are the same as those in Example 1, except that the time of the intermediate treatment is 60 s.

[0076] Example 12

[0077] The steps and parameters are the same as those in Example 1, except that the time for the middle treatment is 70 s.

[0078] Comparative Example 1

[0079] A method for treating pore-forming corrosion of a corrosion foil, comprising the following steps:

[0080] S1. Put the aluminum foil into a solution containing 5 wt% sodium hydroxide for pretreatment, the pretreatment time is 40 s, and the pretreatment temperature is 60 °C;

[0081] S2. Put the pretreated aluminum foil into a mixed solution containing 40 wt% sulfuric acid, 8 wt% nitric acid and 0.5 wt% aluminum ions for first-stage pore formation, and apply a first decaying current; the current density of the initial current of the first decaying current is 1.5 A / cm2, and it decays to 0.3 A / cm within 12 s 2 ; then from 0.3 A / cm 2 , and decays to 0.08 A / cm within 6 s 2 to complete the pore formation;

[0082] S3. Sequentially repeat S1. to S2. for the treated aluminum foil, and repeat 4 times to obtain a pore-forming aluminum foil.

[0083] Comparative Example 2

[0084] A method for treating pore-forming corrosion of a corrosion foil, comprising the following steps:

[0085] S1. Put the aluminum foil into a solution containing 5 wt% sodium hydroxide for pretreatment, the pretreatment time is 40 s, and the pretreatment temperature is 60 °C;

[0086] S2. Put the pretreated aluminum foil into a mixed solution containing 40 wt% sulfuric acid, 8 wt% nitric acid and 0.5 wt% aluminum ions for first-stage pore formation, and apply a first decaying current; the current density of the initial current of the first decaying current is 1.5 A / cm 2 , and decays to 0.75 A / cm within 7.5 s 2 ;

[0087] S3. Disconnect the current, and use a solution containing 2 wt% phosphoric acid and 0.05 wt% polyethylene glycol for middle treatment, the middle treatment time is 40 s, and the middle treatment temperature is 60 °C;

[0088] S3. Continue to apply electricity to the aluminum foil after the middle treatment for second-stage pore formation, and apply a second decaying current; the current density of the initial current of the second decaying current is 0.75 A / cm 2 , and decays to 0.08 A / cm within 10.5 s 2 to complete the pore formation;

[0089] S4. Repeat steps S1. to S3. on the processed aluminum foil successively for 4 times to obtain the porous aluminum foil.

[0090] Comparative Example 3

[0091] A treatment method for pore formation corrosion of preparing etched foil, comprising the following steps:

[0092] S1. Put the aluminum foil into a solution containing 5wt% sodium hydroxide for pretreatment. The pretreatment time is 40s, and the pretreatment temperature is 60°C;

[0093] S2. Put the pretreated aluminum foil into a mixed solution containing 40wt% sulfuric acid, 8wt% nitric acid and 0.5wt% aluminum ions for the first-stage pore formation, and apply a first decaying current; the current density of the initial current of the first decaying current is 1.5A / cm2, and it decays to 0.09A / cm within 15s 2 ;

[0094] S3. Disconnect the current, and use a solution containing 2wt% phosphoric acid and 0.05wt% polyethylene glycol for intermediate treatment. The intermediate treatment time is 40s, and the intermediate treatment temperature is 60°C;

[0095] S3. Continue to apply electricity to the aluminum foil after intermediate treatment for the second-stage pore formation, and apply a second decaying current; the current density of the initial current of the second decaying current is 0.09A / cm 2 , and it decays to 0.08A / cm within 3s 2 Complete the pore formation;

[0096] S4. Repeat steps S1. to S3. on the processed aluminum foil successively for 4 times to obtain the porous aluminum foil.

[0097] Comparative Example 4

[0098] The steps and parameters are the same as those in Example 1, except that a solution containing 2wt% phosphoric acid and 0.003wt% polyethylene glycol is used for intermediate treatment.

[0099] Comparative Example 5

[0100] The steps and parameters are the same as those in Example 1, except that a solution containing 2wt% phosphoric acid and 0.1wt% polyethylene glycol is used for intermediate treatment.

[0101] Comparative Example 6

[0102] The steps and parameters are the same as those in Example 1, except that a solution containing 0.8wt% phosphoric acid and 0.05wt% polyethylene glycol is used for intermediate treatment.

[0103] Comparative Example 7

[0104] The steps and parameters are the same as those in Example 1, except that a solution containing 8 wt% phosphoric acid and 0.05 wt% polyethylene glycol is used for intermediate treatment.

[0105] Example 13

[0106] A method for preparing an etched foil, comprising the following steps:

[0107] Put the pore-forming aluminum foils in Examples 1-12 and Comparative Examples 1-7 above into a solution containing 8 wt% nitric acid and 0.7 wt% aluminum ions at 70 °C for power-on etching. The current density of the power-on etching is 0.15 A / cm 2 , and the power-on time of the power-on etching is 600 s to obtain an enlarged-pore aluminum foil;

[0108] After putting the enlarged-pore aluminum foil into a solution containing 5 wt% nitric acid and 0.4 wt% aluminum ions for 60 s, then carry out normal-temperature water washing treatment with deionized water for 20 minutes. After washing, dry and collect the foil. The etched foils prepared from the pore-forming aluminum foils after the treatment methods in Examples 1-12 are etched foils 1-12, and the etched foils prepared from the pore-forming aluminum foils after the treatment methods in Comparative Examples 1-7 are comparative etched foils 1-7.

[0109] Performance test:

[0110] Use a scanning electron microscope to analyze the cross-sectional morphology of the etched foil 1 and the comparative etched foil 1 prepared by the above method. The results are as Figure 1 and Figure 2 shown.

[0111] Compare Figure 1 and Figure 2 It can be seen that the corrosion holes of the etched foil 1 are relatively neat and the sandwich layer is relatively uniform, while the corrosion holes of the comparative etched foil 1 are uneven, and the uniformity of the sandwich layer is significantly worse than that of the etched foil 1.

[0112] Carry out specific capacitance, tensile strength and bending performance tests on the etched foils 1-12 and the comparative etched foils 1-7 prepared by the above method. The results are shown in Table 1.

[0113] Bending performance test method: The size of the etched foil is 10 mm * 150 mm (the punching burr should be less than 0.1 mm). Use a bending tester of model MIT-DA of YAFENG Company. The test conditions are that the radius of curvature at the bending part is R1.0 ± 0.1 mm, the load is 2.5 ± 0.5 N, the bending angle is 90 ± 2°, the bending back-and-forth speed is 6 times / s, and the distance between the upper and lower chucks is 70 ± 2 mm.

[0114] Tensile test method: The size of the etched foil is 10 ± 0.3 mm * 150 ± 5 mm (the punching burr should be less than 0.1 mm). Use the WZL-100 type tensile tester developed by Hangzhou Qingtong Instrument Development Company. The test tensile speed is 10 ± 1 mm / min, and measure the tensile force at break.

[0115] Specific capacitance test method: Subject the above-mentioned etched foils 1 - 12 and the comparative etched foils 1 - 7 to formation treatment at 850 V in a 70 g / L boric acid solution at 90 °C. Then use the ZX8516B type electrostatic capacitance tester of Changzhou Zhixin Precision Electronics Company. The measurement accuracy is ±2%, the test frequency is 120 ± 5 HZ, the measurement voltage is below 0.5 Vrms, the bath solution composition: 1000 mL of pure water, 80 g of ammonium pentaborate, and the test temperature is 30 ± 2 °C.

[0116] Table 1 Test results of etched foils 1 - 13 and comparative etched foils 1 - 7

[0117]

[0118] As can be seen from Table 1, the specific capacitance of the etched foil prepared by using the pore-forming etching treatment method of the present application can reach 0.364 μf / cm 2 Above, the bending can reach more than 178 times, the tensile force is not less than 22.8 N / cm, and the holes of the etched foil are neat and the sandwich layer is relatively uniform.

[0119] By comparing etched foil 1 and etched foils 3 - 5, it can be seen that when the concentration of the additive in the middle treatment solution is 0.03 - 0.05 wt%, the specific capacitance of the prepared etched foil is further improved, and the specific capacitance is not less than 0.372 μf / cm 2 .

[0120] By comparing etched foil 1 and etched foils 6 - 8, it can be seen that when the concentration of phosphoric acid in the middle treatment solution is 2 wt - 4 wt%, the specific capacitance and bending performance of the prepared etched foil are further improved, and the specific capacitance is not less than 0.388 μf / cm 2 , and the bending is not less than 204 times.

[0121] By comparing etched foil 1 and etched foils 9 - 12, it can be seen that when the temperature of the middle treatment is 60 - 85 °C and the time of the middle treatment is 20 - 60 s, the specific capacitance and bending performance of the prepared etched foil are further improved, and the specific capacitance is not less than 0.389 μf / cm 2 , and the bending is not less than 204 times.

[0122] As can be seen from the comparative etched foil 1, when the pore-forming etching treatment method does not undergo middle treatment, the specific capacitance of the prepared etched foil is only 0.332 μf / cm 2 , the bending is only more than 165 times, and the holes of the prepared etched foil are not neat and the sandwich layer is uneven.

[0123] It can be seen from the comparison of etched foils 2 and 3 that when the middle treatment is carried out at a time that is not 10-20% of the initial current of the first decaying current, the performance of the prepared etched foil is not significantly improved.

[0124] It can be seen from the comparison of etched foils 4-7 that when the concentration of phosphoric acid in the middle treatment solution is not within 1 wt% - 5 wt%, or the additive is not within the range of 0.005 wt% - 0.06 wt%, the performance of the prepared etched foil is not significantly improved.

[0125] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for treating the pore-forming corrosion of preparing etched foils, characterized in that, It includes the following steps: S1. Place the pretreated aluminum foil into the pore-forming solution for the first-stage pore formation, and apply a first decaying current with an initial current density of i0; the initial current density is 1.2 - 1.8 A / cm 2 ; the pore-forming solution is a mixed solution containing 35wt - 45wt% sulfuric acid, 7wt - 9wt% hydrochloric acid, and 0.4wt - 0.6wt% aluminum ions; S2. When the current density decays to 10-20% of i0, disconnect the current and put the aluminum foil into the intermediate treatment solution for intermediate treatment; S3. Put the aluminum foil after intermediate treatment into the pore-forming solution for secondary pore-forming, and apply a second decaying current. The current density of the initial current of the second decaying current is 10-20% of i0, and the pore-forming is completed when the current density decays to 2-8% of i0; S4. Repeat S1.-S3. for the treated aluminum foil in sequence, and the number of repetitions is at least 3 times; Among them, the intermediate treatment solution is a solution containing 1wt-5wt% of phosphoric acid and 0.005wt-0.06wt% of an additive; the additive is polyethylene glycol.

2. The processing method according to claim 1, characterized in that The intermediate treatment solution is a solution containing 1wt-5wt% of phosphoric acid and 0.03wt-0.05wt% of an additive.

3. The processing method according to claim 1, characterized in that The intermediate treatment solution is a solution of 3wt-4wt% of phosphoric acid and 0.03wt-0.05wt% of an additive.

4. The processing method according to claim 1, characterized in that, The time of the intermediate treatment is 20-60s.

5. The processing method according to claim 1, characterized in that The temperature of the intermediate treatment is 60-85°C.

6. The processing method according to claim 1, characterized in that, The current density of the first decaying current decays to 10-20% of i0 within 8-16s.

7. The processing method according to claim 1, wherein The current density of the second decaying current decays to 2-8% of i0 within 2-10s.

8. A foamed aluminum foil, characterized in that, Prepared by using the treatment method according to any one of claims 1-7.

9. A method for preparing an etched foil, characterized in that, The pore-forming aluminum foil prepared in claim 8 is subjected to reaming corrosion, post-treatment, and drying treatment in sequence.

10. An etched foil, characterized in that, Prepared by using the preparation method according to claim 9.

Images