A method for reaming a low pressure hard anodized foil and applications thereof

Abstract

The application discloses a low-voltage hard-state corrosion foil hole expanding corrosion method and application. The low-voltage hard-state corrosion foil hole expanding corrosion method is that after aluminum foil is put into a hole expanding corrosion solution, electrochemical corrosion is carried out for 5 times, and the current density, power frequency and corrosion time are adjusted correspondingly each time. The value of the current density presents a peak-shaped change of first increasing and then decreasing, and the power frequency presents a gradient change of gradually decreasing. In the hole expanding corrosion stage of the aluminum foil, the low-voltage hard-state corrosion foil with deep corrosion layer thickness and large corrosion hole size is obtained by adjusting the current density and the power frequency, the through-hole phenomenon is not generated, the effectiveness of the corrosion hole is improved, the specific capacity and cutting width performance of the low-voltage (greater than 80Vf) hard-state electrode foil are improved, the capacity of the aluminum electrolytic capacitor is further improved, and the problem of uneven corrosion layer depth of the electrode foil is solved, and the thickness of the core layer of the electrode foil is uniform.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aluminum foil preparation, in particular to a hole expanding and etching method of low-pressure hard-state etching foil and application. BACKGROUND

[0002] In recent years, with the development of electronic products towards light, thin, short and small, people have also put forward the requirements of miniaturization and high capacity for important electronic components of electronic products, i.e. aluminum electrolytic capacitors. The capacity of aluminum electrolytic capacitors is closely related to its structure. The aluminum electrolytic capacitor is composed of anode foil, cathode foil, electrolyte and auxiliary lead and shell, and the anode foil and cathode foil are both electrode foils prepared by etching and formation process of aluminum foil. At the same time, the electrode foil is also the component that has the greatest impact on the capacity of aluminum electrolytic capacitor, that is, the key to improve the capacity of aluminum electrolytic capacitor lies in improving the specific capacity of electrode foil.

[0003] The key to improve the specific capacity of electrode foil lies in increasing the unit specific surface area of electrode foil. At present, the electrochemical etching treatment is usually used to increase the specific surface area of electrode foil, so in order to improve the specific capacity of electrode foil, the existing technology has made many improvements on the electrochemical etching treatment method, mainly focusing on the following schemes: (1) changing the electrochemical etching frequency, gradually reducing from high frequency to low frequency to perform multiple step etching on aluminum foil; (2) applying the same current multiple times, under the condition of keeping the current density and time unchanged, applying the current multiple times to perform multiple etching on aluminum foil; (3) multiple alternating frequency etching, gradually decreasing the current density and frequency in a step-by-step manner to perform multiple etching on aluminum foil. However, the improvement schemes of the electrochemical etching treatment method of the existing technology are for soft-state low-pressure electrode foil, low-pressure electrode foil less than 80Vf and high-pressure electrode foil. When these improvement schemes are used for low-pressure hard-state electrode foil greater than 80Vf, the specific capacity of the low-pressure hard-state electrode foil cannot be improved well, and there is a problem of uneven etching layer depth of electrode foil, i.e. uneven core layer of electrode foil, which will affect the performance of electrode foil. Therefore, it is of great significance to develop a new hole expanding and etching method of low-pressure hard-state etching foil to improve the specific capacity of low-pressure hard-state electrode foil greater than 80Vf and keep the thickness of electrode foil core layer uniform. SUMMARY

[0004] The primary object of the present application is to overcome the drawbacks of the prior art and provide a low-voltage hard-state etching foil hole-expanding etching method. In the hole-expanding etching stage of the aluminum light foil, by matching the current density which increases first and then decreases in peak shape with the power frequency which gradually decreases in gradient, a low-voltage hard-state etching foil with deep etching layer thickness and large etching hole size is obtained, without the occurrence of hole connection, improving the effectiveness of the etching holes and being beneficial to improving the specific capacity and cutting width performance of the low-voltage (greater than 80Vf) hard-state electrode foil, thereby improving the capacity of the aluminum electrolytic capacitor, and solving the problem of uneven etching layer depth of the electrode foil, and the thickness of the core layer of the electrode foil is also uniform.

[0005] Another object of the present application is to provide a low-voltage hard-state etching foil hole-expanding etching method.

[0006] Another object of the present application is to provide a low-voltage hard-state etching foil hole-expanding etching method.

[0007] Another object of the present application is to provide a low-voltage hard-state etching foil hole-expanding etching method.

[0008] Another object of the present application is to provide a low-voltage hard-state etching foil hole-expanding etching method.

[0009] The technical scheme adopted by the present application to achieve the above technical objects is as follows:

[0010] A low-voltage hard-state etching foil hole-expanding etching method, comprising the following steps:

[0011] The aluminum light foil is placed in the hole-expanding etching liquid, and then the following steps are sequentially performed:

[0012] (1) at a current density of 0.04-0.10 A / cm 2 , power frequency 50 Hz, etching for 2 min;

[0013] (2) at a current density of 0.10-0.18 A / cm 2 , power frequency 50 Hz, etching for 2 min;

[0014] (3) at a current density of 0.20-0.26 A / cm 2 , power frequency 50 Hz, etching for 3 min;

[0015] (4) at a current density of 0.16-0.22 A / cm 2 , power frequency 25-45 Hz, etching for 3 min;

[0016] (5) at a current density of 0.13-0.18 A / cm 2The corrosion effect is 3 minutes under the power frequency of 15-35 Hz.

[0017] The present application can improve the specific capacity and cutting width performance of the low-voltage (more than 80Vf) hard-state electrode foil by adjusting the current density and power frequency during the hole-expanding corrosion stage of the aluminum light foil, and further improve the capacity of the aluminum electrolytic capacitor. Moreover, the problem of uneven corrosion layer depth of the electrode foil can be solved, and the thickness of the core layer of the electrode foil is kept uniform.

[0018] During the hole-expanding corrosion stage, the current density is increased first and then decreased in a peak shape, because in the stage of increasing current density, the corrosion is mainly hole-expanding, and the corrosion layer depth is increased as much as possible, and in the stage of decreasing current density, the corrosion is mainly hole-expanding, and the corrosion hole size is enlarged as much as possible. If a larger current density is always used, the corrosion hole size cannot be enlarged, and if a smaller current density is always used, the corrosion layer depth cannot be increased.

[0019] Therefore, by increasing the current density first and then decreasing it in a peak shape, the low-voltage hard-state corrosion foil with deep corrosion layer depth and large corrosion hole size can be obtained. Moreover, this method can better control the hole-expanding and hole-enlarging, and the hole-expanding and hole-enlarging are not combined, and the effectiveness of the corrosion hole is improved. These are beneficial to improve the specific capacity and cutting width performance of the low-voltage (more than 80Vf) hard-state electrode foil, and further improve the capacity of the aluminum electrolytic capacitor.

[0020] In addition, during the hole-expanding corrosion stage, the power frequency is gradually decreased in a gradient, in order to complement the current density, assist hole-expanding in the stage of increasing current density, increase the corrosion layer depth, and assist hole-expanding in the stage of decreasing current density, and enlarge the corrosion hole size. Specifically, the higher power frequency makes the electrochemistry corrosion times per second more and short, and forms smaller size corrosion holes, and at this time, the larger current density is beneficial to increase the corrosion layer depth. The lower power frequency makes the electrochemistry corrosion times per second less and long, and forms larger size corrosion holes, and at this time, the smaller current density is beneficial to enlarge the corrosion hole size.

[0021] In addition, by increasing the current density first and then decreasing it in a peak shape and gradually decreasing the power frequency in a gradient, the corrosion layer depth of the electrode foil obtained by corrosion is uniform, and the thickness of the core layer of the electrode foil is kept uniform.

[0022] In summary, in the expansion hole etching stage of the aluminum light foil, the low-voltage hard-state etching foil with deep etching layer thickness and large etching hole size is obtained by the cooperation of the current density with the first increasing and then decreasing peak shape change and the power frequency with the gradually decreasing gradient change, without the occurrence of the hole phenomenon, the effectiveness of the etching hole is improved, which is also beneficial to improve the specific capacity and cutting width performance of the low-voltage (greater than 80Vf) hard-state electrode foil, thereby improving the capacity of the aluminum electrolytic capacitor, and the problem of uneven etching layer depth of the electrode foil is solved, and the thickness of the core layer of the electrode foil is also uniform.

[0023] Preferably, the expansion hole etching method of the low-voltage hard-state etching foil comprises the following steps:

[0024] The aluminum light foil is placed in the expansion hole etching liquid, and then the following steps are sequentially performed:

[0025] (1) under the current density of 0.06-0.08 A / cm 2 , the power frequency of 50 Hz, etching for 2 min;

[0026] (2) under the current density of 0.14-0.16 A / cm 2 , the power frequency of 50 Hz, etching for 2 min;

[0027] (3) under the current density of 0.23-0.25 A / cm 2 , the power frequency of 50 Hz, etching for 3 min;

[0028] (4) under the current density of 0.18-0.20 A / cm 2 , the power frequency of 32-42 Hz, etching for 3 min;

[0029] (5) under the current density of 0.14-0.16 A / cm 2 , the power frequency of 25-32 Hz, etching for 3 min.

[0030] Preferably, the expansion hole etching liquid comprises hydrochloric acid 4-6N, sulfuric acid 0.2-0.4N, and aluminum chloride 0.1-1.2N.

[0031] A preparation method of a low-voltage hard-state etching foil, comprising the following steps:

[0032] S1: pretreating the aluminum light foil with a hydrochloric acid solution;

[0033] S2: hole etching the aluminum light foil treated in step S1 with an etching liquid;

[0034] S3: intermediate treatment of the aluminum light foil treated in step S2 with an intermediate treatment liquid;

[0035] S4: treating the aluminum light foil treated in step S3 by the hole-expanding etching method of the low-voltage hard-state etching foil as described above;

[0036] S5: post-treating the aluminum light foil treated in step S4 by a sulfuric acid solution, thereby obtaining the low-voltage hard-state etching foil.

[0037] The present application improves the preparation method of the low-voltage hard-state etching foil by using the hole-expanding etching method of the low-voltage hard-state etching foil, solves the problem of uneven electrode foil core layer, and improves the specific capacity and cutting width performance of the low-voltage (greater than 80Vf) hard-state electrode foil.

[0038] In addition, the preparation method of the low-voltage hard-state etching foil has the advantages of low cost and simple operation, and is conducive to further expanding the production scale of aluminum electrolytic capacitors.

[0039] Preferably, step S1 specifically comprises: placing the aluminum light foil into a hydrochloric acid solution and treating at a temperature of 50-80℃ for 0.5-1min.

[0040] Preferably, step S2 specifically comprises: placing the aluminum light foil treated in step S1 into an etching solution and treating at a temperature of 50-80℃, a current density of 0.1-0.30A / cm 2 , and a power frequency of 50Hz for 8-25s.

[0041] Preferably, the etching solution comprises hydrochloric acid 3-5N, sulfuric acid 0.01-0.1N, and aluminum chloride 0.4-1.2N.

[0042] Preferably, step S3 specifically comprises: placing the aluminum light foil treated in step S2 into a medium treatment solution and treating at a temperature of 50-80℃ for 30-100s.

[0043] Preferably, the medium treatment solution comprises hydrochloric acid 4-6N, aluminum chloride 0.4-1.8N, and metal halide 0.1-2ppm.

[0044] More preferably, the metal halide is one or more of copper chloride, iron chloride, and potassium chloride.

[0045] Preferably, step S5 specifically comprises: placing the aluminum light foil treated in step S4 into a sulfuric acid solution, soaking and treating at a temperature of 40-65℃ for 1-3min, then washing with water and soaking in water at 45℃ for 5min, and finally annealing at 400-600℃ for 1-2min, thereby obtaining the low-voltage hard-state etching foil.

[0046] A low-voltage hard-state etching foil prepared by the preparation method of the low-voltage hard-state etching foil as described above.

[0047] A low-voltage hard-state electrode foil is obtained by formation of the above low-voltage hard-state etching foil.

[0048] Preferably, the working voltage of the low-voltage hard-state electrode foil is greater than 80Vf.

[0049] More preferably, the working voltage of the low-voltage hard-state electrode foil is 80-150Vf.

[0050] An application of the above low-voltage hard-state electrode foil in preparation of aluminum electrolytic capacitor.

[0051] Compared with the prior art, the present application has the following advantages:

[0052] In the present application, the low-voltage hard-state etching foil with deep etching layer thickness and large etching hole size is obtained by cooperation of the current density with the peak shape changing from increasing to decreasing and the power frequency with the gradient changing gradually in the reaming etching stage of the aluminum light foil, and the etching hole effectiveness is improved, the specific capacity and cutting width performance of the low-voltage (greater than 80Vf) hard-state electrode foil are improved, and the capacity of the aluminum electrolytic capacitor is improved, and the problem of uneven etching layer depth of the electrode foil is solved, and the core layer of the electrode foil also maintains uniform thickness.

[0053] In addition, the preparation method of the low-voltage hard-state etching foil has the advantages of low cost and simple operation, and is beneficial to further expand the production scale of the aluminum electrolytic capacitor. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 Figure 4 is a scanning electron microscope image of the section of the low-voltage hard-state etching foil of Example 1.

[0055] Figure 2 Figure 6 is a scanning electron microscope image of the section of the etching foil of Comparative Example 4. DETAILED DESCRIPTION

[0056] The present application will be further described below in conjunction with examples. These examples are only used to illustrate the present application and are not used to limit the scope of the present application. The experimental methods not specified in the following example are usually carried out according to the conventional conditions in the art or according to the conditions suggested by the manufacturers; the raw materials, reagents, etc. used, if not specifically stated, are all raw materials and reagents that can be obtained from conventional markets or commercial channels. Any non-essential changes and substitutions made by those skilled in the art on the basis of the present application shall fall within the scope of the present application.

[0057] The descriptions of the etching solution, intermediate treatment solution and reaming etching solution used in each embodiment and comparative example of the present application are as follows:

[0058] The etching solution includes hydrochloric acid 4N, sulfuric acid 0.05N and aluminum trichloride 0.8N.

[0059] The intermediate treatment solution comprises 5N hydrochloric acid, 1.2N aluminum trichloride and 1 ppm copper chloride.

[0060] The hole-expanding etching solution comprises 5N hydrochloric acid, 0.3N sulfuric acid and 0.7N aluminum trichloride.

[0061] Example 1

[0062] This example provides a low-voltage hard etching foil, and a method for preparing the same, which comprises the following steps:

[0063] S1: placing the aluminum light foil into a hydrochloric acid solution and treating it at a temperature of 70°C for 1 minute;

[0064] S2: placing the aluminum light foil treated in step S1 into an etching solution and treating it at a temperature of 71°C, a current density of 0.15 A / cm 2 , and a power frequency of 50 Hz for 20 seconds;

[0065] S3: placing the aluminum light foil treated in step S2 into an intermediate treatment solution and treating it at a temperature of 70°C for 1 minute;

[0066] S4: placing the aluminum light foil into a hole-expanding etching solution, and then sequentially performing the following steps:

[0067] (1) etching for 2 minutes at a current density of 0.07 A / cm 2 and a power frequency of 50 Hz;

[0068] (2) etching for 2 minutes at a current density of 0.15 A / cm 2 and a power frequency of 50 Hz;

[0069] (3) etching for 3 minutes at a current density of 0.24 A / cm 2 and a power frequency of 50 Hz;

[0070] (4) etching for 3 minutes at a current density of 0.19 A / cm 2 and a power frequency of 40 Hz;

[0071] (5) etching for 3 minutes at a current density of 0.15 A / cm 2 and a power frequency of 30 Hz;

[0072] S5: placing the aluminum light foil treated in step S4 into a sulfuric acid solution and treating it by immersion at a temperature of 55°C for 2 minutes, then washing it with water and immersing it in water at 45°C for 5 minutes, and finally annealing it at 460°C for 1 minute to obtain a low-voltage hard etching foil.

[0073] Example 2

[0074] This embodiment provides a low-voltage hard-state etching foil, the preparation method of which is consistent with that of Example 1 except for step S4, specifically, step S4 is: placing the aluminum light foil into a hole-expanding etching solution, and then sequentially performing the following steps:

[0075] (1) etching for 2 min at a current density of 0.04 A / cm 2 , and a power supply frequency of 50 Hz;

[0076] (2) etching for 2 min at a current density of 0.10 A / cm 2 , and a power supply frequency of 50 Hz;

[0077] (3) etching for 3 min at a current density of 0.20 A / cm 2 , and a power supply frequency of 50 Hz;

[0078] (4) etching for 3 min at a current density of 0.16 A / cm 2 , and a power supply frequency of 40 Hz;

[0079] (5) etching for 3 min at a current density of 0.13 A / cm 2 , and a power supply frequency of 30 Hz.

[0080] Example 3

[0081] This embodiment provides a low-voltage hard-state etching foil, the preparation method of which is consistent with that of Example 1 except for step S4, specifically, step S4 is: placing the aluminum light foil into a hole-expanding etching solution, and then sequentially performing the following steps:

[0082] (1) etching for 2 min at a current density of 0.10 A / cm 2 , and a power supply frequency of 50 Hz;

[0083] (2) etching for 2 min at a current density of 0.18 A / cm 2 , and a power supply frequency of 50 Hz;

[0084] (3) etching for 3 min at a current density of 0.26 A / cm 2 , and a power supply frequency of 50 Hz;

[0085] (4) etching for 3 min at a current density of 0.22 A / cm 2 , and a power supply frequency of 40 Hz;

[0086] (5) etching for 3 min at a current density of 0.18 A / cm 2 , and a power supply frequency of 30 Hz.

[0087] Example 4

[0088] This example provides a low-voltage hard-state etching foil, the preparation method of which is consistent with that of Example 1 except for step S4, specifically, step S4 is as follows: the aluminum light foil is put into a hole-expanding etching solution, and then the following steps are sequentially performed:

[0089] (1) etching for 2 min at a current density of 0.06 A / cm 2 , and a power supply frequency of 50 Hz;

[0090] (2) etching for 2 min at a current density of 0.14 A / cm 2 , and a power supply frequency of 50 Hz;

[0091] (3) etching for 3 min at a current density of 0.23 A / cm 2 , and a power supply frequency of 50 Hz;

[0092] (4) etching for 3 min at a current density of 0.18 A / cm 2 , and a power supply frequency of 40 Hz;

[0093] (5) etching for 3 min at a current density of 0.14 A / cm 2 , and a power supply frequency of 30 Hz.

[0094] Example 5

[0095] This example provides a low-voltage hard-state etching foil, the preparation method of which is consistent with that of Example 1 except for step S4, specifically, step S4 is as follows: the aluminum light foil is put into a hole-expanding etching solution, and then the following steps are sequentially performed:

[0096] (1) etching for 2 min at a current density of 0.08 A / cm 2 , and a power supply frequency of 50 Hz;

[0097] (2) etching for 2 min at a current density of 0.16 A / cm 2 , and a power supply frequency of 50 Hz;

[0098] (3) etching for 3 min at a current density of 0.25 A / cm 2 , and a power supply frequency of 50 Hz;

[0099] (4) etching for 3 min at a current density of 0.20 A / cm 2 , and a power supply frequency of 40 Hz;

[0100] (5) etching for 3 min at a current density of 0.16 A / cm 2 , and a power supply frequency of 30 Hz.

[0101] Examples 6-9

[0102] Examples 6-9 provide different low pressure hard anodized foils prepared according to the same procedure as Example 1 except for step S4, and the same experimental parameters (1) - (3) in step S4 as Example 1, and the same current density and etching time (4) - (5) in step S4 as Example 1, but different power supply frequencies as shown in the following table:

[0103] Table 1. Power supply frequency (4) in step S4 for Examples 6-9

[0104] Example Power frequency (Hz) Example 6 45 Example 7 25 Example 8 42 Example 9 32

[0105] Table 2. Power supply frequency (5) in step S4 for Examples 6-9

[0106] Example Power frequency (Hz) Example 6 35 Example 7 15 Example 8 32 Example 9 25

[0107] Comparative Example 1

[0108] This comparative example provides a foil prepared according to the same procedure as Example 1 except for step S4, in which the current density is gradually decreased in a stepwise manner, and the same experimental parameters (1) - (3) in step S4 as Example 1. Specifically, step S4 is as follows:

[0109] (1) etching for 2 min at a current density of 0.24 A / cm 2 , and a power supply frequency of 50 Hz;

[0110] (2) etching for 2 min at a current density of 0.19 A / cm 2 , and a power supply frequency of 50 Hz;

[0111] (3) etching for 3 min at a current density of 0.15 A / cm 2 , and a power supply frequency of 50 Hz;

[0112] (4) etching for 3 min at a current density of 0.15 A / cm 2 , and a power supply frequency of 40 Hz;

[0113] (5) etching for 3 min at a current density of 0.07 A / cm 2 , and a power supply frequency of 30 Hz.

[0114] Comparative Example 2

[0115] This comparative example provides a foil prepared according to the same procedure as Example 1 except for step S4, in which the current density is maintained at 0.19 A / cm 2 , and the same experimental parameters (1) - (3) in step S4 as Example 1.

[0116] Comparative Example 3

[0117] This comparative example provides a corrosion foil, the preparation method of which is different from that of Example 1 in that the current density in step S4 is always kept at 0.19 A / cm

[0118] Comparative Example 4

[0119] This comparative example provides a corrosion foil, the preparation method of which is different from that of Example 1 in that the current density in step S4 is always kept at 0.19 A / cm 2 , the power frequency is always kept at 50 Hz, and the rest is consistent with Example 1.

[0120] Comparative Example 5

[0121] This comparative example provides a corrosion foil, the preparation method of which is different from that of Example 1 in that step S4 only has 3 steps, specifically: the aluminum light foil is placed into the hole expansion etching solution, and then the following steps are performed in sequence:

[0122] (1) etching for 2 min at a current density of 0.07 A / cm 2 , a power frequency of 50 Hz;

[0123] (2) etching for 3 min at a current density of 0.24 A / cm 2 , a power frequency of 50 Hz;

[0124] (3) etching for 3 min at a current density of 0.15 A / cm 2 , a power frequency of 30 Hz.

[0125] This comparative example attempts to complete the peak-shaped change of the current density first increasing and then decreasing through 3 steps, but it is found in the experiment that the aluminum light foil surface is polarized and the etching of the entire step S4 cannot be completed.

[0126] Performance Test

[0127] After the low-voltage hard-state etching foil of Example 1 and the etching foils of each comparative example are formed at 140 V, the cross sections of each are analyzed by scanning electron microscopy.

[0128] Figure 1 is the scanning electron microscopy graph of the cross section of the low-voltage hard-state etching foil of Example 1, Figure 2 is the scanning electron microscopy graph of the cross section of the etching foil of Comparative Example 4. From Figure 1 and 2It can be seen that the electrode foil of Example 1 has uniform corrosion layer depth and uniform core layer thickness, and the electrode foil of Comparative Example 4 has uneven corrosion layer and uneven core layer thickness, which shows that the electrode foil obtained by the present application has uniform corrosion layer depth and uniform core layer thickness by increasing the current density in a peak shape and gradually reducing the power frequency in a gradient shape. Figure 2 Similarly, the electrode foil of Comparative Examples 1-3 also has uneven corrosion layer and uneven core layer thickness.

[0129] According to "People's Republic of China Electronics Industry Standard SJ / T1140-2012: Electrode Foil for Aluminum Electrolytic Capacitors", the low-voltage hard-state corrosion foils of each example and the corrosion foils of each comparative example were subjected to 140V formation to obtain low-voltage hard-state electrode foils and electrode foils, and then the specific capacity, tensile strength, bending resistance and cutting width performance of the electrode foils were tested, and the specific capacity / unit weight loss of each example and comparative example was calculated.

[0130] The test method for cutting width performance is as follows: each example low-voltage hard-state electrode foil and each comparative example electrode foil after 140V formation is cut into test strips of different widths, and then a breaking experiment is performed, until the test strip cannot be broken, then the width of the test strip is the minimum cutting width, which is used to represent the cutting width performance of the test strip, and the smaller the minimum cutting width, the better the cutting width performance. In addition, the minimum cutting width is rated as follows:

[0131] Excellent means that the minimum cutting width is <0.5cm;

[0132] Good means that the minimum cutting width is 0.5-2.0cm;

[0133] Poor means that the minimum cutting width is >2.0cm.

[0134] Specific capacity / unit weight loss calculation:

[0135] Unit weight loss=(electrode foil initial weight-electrode foil residual weight) / electrode foil area

[0136] Wherein, the electrode foil in the electrode foil initial weight is aluminum foil, the unit is mg, and the weight of the aluminum foil in this test is in the range of 205.6-205.9mg; the electrode foil in the electrode foil residual weight is the corrosion foil after formation, the unit is mg; the electrode foil area is the area of the aluminum foil; the unit of the unit weight loss is mg / cm 2 .

[0137] Specific capacity / unit weight loss=specific capacity*electrode foil area / (electrode foil initial weight-electrode foil residual weight)

[0138] Wherein, the unit of specific capacity is μF / cm 2The unit for specific volume / unit weight loss is μF / mg.

[0139] Table 3 Performance test results of low-pressure hard electrode foils in each embodiment and electrode foils in each comparative embodiment.

[0140] Sample 140V specific capacitance (pF / cm 2 ) Minimum cut width / grade Specific volume / unit weight loss (μF / mg) Example 1 6.8 Good 0.60 Example 2 5.6 Good 0.59 Example 3 6.1 Good 0.50 Example 4 5.8 Good 0.58 Example 5 6.2 Good 0.57 Example 6 6.3 Good 0.56 Example 7 6.1 Good 0.52 Example 8 6.4 Good 0.56 Example 9 6.1 Good 0.53 Comparative Example 1 2.1 Good 0.30 Comparative Example 2 5.2 Poor 0.44 Comparative Example 3 5.2 Poor 0.43 Comparative Example 4 5.1 Poor 0.41

[0141] As shown in Table 3:

[0142] (1) The specific capacitance of the low-voltage hard state electrode foil in Example 1 at 140V is 6.8μF / cm. 2 This is greater than the 2.1 μF / cm of Comparative Example 1, which used a current density that gradually decreased. 2 It is also greater than the current density that was always maintained at 0.19 A / cm². 2 Comparative Example 2: 5.8 μF / cm 2 It is also greater than the 5.8 μF / cm of Comparative Example 3, which used a power supply frequency that was always kept at 50 Hz. 2 This is greater than using a current density that is always maintained at 0.19 A / cm². 2 The power supply frequency is always maintained at 50Hz. Comparative Example 4 has a power supply of 5.6 μF / cm. 2 This demonstrates that by combining a current density that first increases and then decreases in a peak shape with a power supply frequency that gradually decreases in a gradient, the specific capacitance of the low-voltage hard-state electrode foil of the present invention is improved. At the same time, this also helps to improve the capacitance of aluminum electrolytic capacitors.

[0143] (2) The minimum cutting width also exhibits a similar phenomenon to that of 140V specific capacitance, indicating that the cutting width performance of the low-voltage hard state electrode foil of the present invention has also been improved.

[0144] (3) The tensile strength of the low-pressure hard electrode foil in each embodiment of the present invention and the electrode foil in each comparative example are all greater than 22 MPa and the number of bends is all greater than 77, which meet the daily use requirements of the electrode foil. This shows that the performance of the low-pressure hard electrode foil of the present invention has not decreased due to the improvement of specific volume and cutting width performance.

[0145] (4) In all embodiments of the present invention, the combined specific volume and cutting width performance of Embodiment 1 is the best among all embodiments.

[0146] (5) In all examples and comparative examples, the value of specific capacity per unit weight loss of Example 1 is the largest, indicating that the low-pressure hard-type electrode foil of Example 1 has the largest specific capacity when the unit weight loss is a constant value, and also indicating that the corrosion layer of Example 1 has no pinholes and peeling phenomenon, and the strength of the core layer of the electrode foil is also relatively appropriate. In addition, if the specific capacity performance of the electrode foil is expressed by the specific capacity per unit weight loss, the size of the unit weight loss value needs to be considered, because when the corrosion amount of the electrode foil is small, the unit weight loss value is small, and even if the specific capacity per unit weight loss value is large at this time, the specific capacity is still small.

[0147] Obviously, the above-mentioned examples of the present application are only examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. All the embodiments do not need to be exhausted here. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A method of reaming a hard anodized foil at low pressure, characterized in that The method comprises the following steps: The aluminum light foil is put into a hole-expanding etching solution, and then the following steps are performed in sequence: (1) under the current density of 0.04-0.10 A / cm 2 , power frequency 50 Hz, corrosion for 2 min; (2) under the current density of 0.10-0.18 A / cm 2 , power frequency 50 Hz, corrosion effect 2 min; (3) at a current density of 0.20-0.26 Acm 2 under a power frequency of 50 Hz, for 3 min; (4) at a current density of 0.16-0.22 A / cm 2 under a power frequency of 25-45 Hz for 3 min; (5) at a current density of 0.13-0.18 A / cm 2 under a power frequency of 15-35 Hz for 3 min; The current density of the steps (1)-(5) presents a peak-shaped change of first increasing and then decreasing.

2. The method of claim 1, wherein the low-pressure hard anodizing foil is formed by a method comprising: The method comprises the following steps: The aluminum light foil is put into a hole-expanding etching solution, and then the following steps are performed in sequence: (1) at a current density of 0.06-0.08 A / cm 2 , a power frequency of 50 Hz, and a corrosion action of 2 min; (2) under the conditions of current density 0.14-0.16 A / cm 2 , power frequency 50 Hz, and corrosion time 2 min; (3) at a current density of 0.23-0.25 A / cm 2 under a power frequency of 50 Hz, for 3 min; (4) at a current density of 0.18-0.20 A / cm 2 under a power frequency of 32-42 Hz for 3 min; (5) at a current density of 0.14 to 0.16 A / cm 2 under a power frequency of 25 to 32 Hz for 3 min.

3. The method of claim 1 or 2, wherein the low-pressure hard anodizing foil is formed by a method comprising: The hole-expanding etching solution comprises 4-6N hydrochloric acid, 0.2-0.4N sulfuric acid and 0.1-1.2N aluminum trichloride.

4. A method for producing a low-pressure hard anodized corrosion foil, characterized by, The method comprises the following steps: S1: pre-treating the aluminum light foil with a hydrochloric acid solution; S2: hole-etching the aluminum light foil treated in step S1 with an etching solution; S3: middle-treating the aluminum light foil treated in step S2 with a middle treatment solution; S4: hole-expanding etching the aluminum light foil treated in step S3 according to the hole-expanding etching method of the low-voltage hard-state etching foil in any one of claims 1-2; S5: post-treating the aluminum light foil treated in step S4 with a sulfuric acid solution, washing with water, soaking in water and finally annealing, to obtain the low-voltage hard-state etching foil.

5. The method of claim 4, wherein the low-pressure hard temper corrosion foil is prepared by the steps of: The step S1 specifically comprises: putting the aluminum light foil into the hydrochloric acid solution and treating at a temperature of 50-80℃ for 0.5-1min. ​ 6. The method of claim 4, wherein the low-pressure hard temper corrosion foil is prepared by the steps of: The step S2 is specifically: placing the aluminum light foil treated by the step S1 into an etching solution, and treating for 8-25 s under the conditions that the temperature is 50-80 ℃, the current density is 0.1-0.30 A / cm 2 , and the power frequency is 50 Hz. The etching solution comprises 3-5N hydrochloric acid, 0.01-0.1N sulfuric acid and 0.4-1.2N aluminum trichloride.

7. The method of claim 4, wherein the low-pressure hard temper corrosion foil is prepared by the steps of: The step S3 specifically comprises: putting the aluminum light foil treated in step S2 into the middle treatment solution and treating at a temperature of 50-80℃ for 30-100s; ​ The middle treatment solution comprises 4-6N hydrochloric acid, 0.4-1.8N aluminum trichloride and 0.1-2ppm metal halide, and the metal halide is one or more of cupric chloride, ferric chloride and potassium chloride; The step S5 specifically comprises: putting the aluminum light foil treated in step S4 into the sulfuric acid solution and soaking at a temperature of 40-65℃ for 1-3min, then washing with water, soaking in 45℃ water for 5min and finally annealing at 400-600℃ for 1-2min, to obtain the low-voltage hard-state etching foil.

8. A low pressure hard temper corrosion foil, characterized in that, Prepared by the preparation method in any one of claims 4-7.

9. A low voltage hard electrode foil, characterized by, The low-voltage hard-state etching foil in claim 8 is subjected to formation.

10. Use of the low-voltage hard-state electrode foil in claim 9 in the preparation of an aluminum electrolytic capacitor.

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