A low-pressure corrosion foil formation process

Abstract

The present invention relates to the field of chemical foil technology, and in particular to a low-voltage corrosion foil chemical process. The low-voltage corrosion foil chemical process of the present invention comprises the following steps: primary chemical treatment, passivation treatment, secondary chemical treatment, passivation treatment, heat treatment, tertiary chemical treatment, water washing, and drying. The aluminum foil obtained by the chemical process of the present invention not only ensures that the capacity and voltage of the aluminum foil are at normal levels, but also improves the hydration resistance of the aluminum foil, further reduces water penetration, reduces leakage current, and prolongs the service life. It can be widely used in information electronic equipment, instrument equipment, electromechanical equipment, and household electronic products.

Description

Technical Field

[0001] The invention relates to the technical field of chemically formed foils, and in particular to a low-pressure corrosion foil chemically formed process. Background Art

[0002] Low-pressure chemical foil is a material that is made by electrolytically treating the surface of aluminum foil to make it highly conductive and corrosion-resistant. Due to its high capacity, low price, easy processing and ease of use, it is widely used in information electronic equipment, instrumentation, electromechanical equipment and household electronic products.

[0003] At present, the commonly used corrosion foil formation process is formation → water washing → heat treatment → formation → water washing → drying. The samples prepared by this method can only test the withstand voltage and capacity, and cannot measure its hydration performance. For example, the patent technical document CN202110402809.7 discloses a formation method of a low-pressure formed foil and the obtained low-pressure formed foil. The invention includes the following steps: first-stage formation, first water washing, phosphoric acid passivation treatment, heat treatment, second water washing, second-stage formation, third water washing, and drying to obtain a low-pressure formed foil. The low-voltage formed foil obtained by the formation method of the invention has a leakage current of ≤14μF / cm 2 , which can effectively improve product stability. However, when using phosphoric acid for passivation treatment, if the phosphoric acid treatment is too strong, the acid will dissolve a part of the amorphous and porous oxide film on the outer layer of the oxide film, further corrode the internal crystalline oxide layer, and even corrode and dissolve the aluminum matrix, which is bound to affect the hydration resistance of the aluminum foil. Summary of the invention

[0004] In view of this, the purpose of the present invention is to propose a low-voltage corrosion foil formation process to provide a formation process that can improve the hydration resistance of the aluminum foil while ensuring that the capacity and voltage of the aluminum foil are at normal levels.

[0005] Based on the above purpose, the present invention provides a low-pressure corrosion foil formation process, comprising the following steps:

[0006] (1) placing the corroded foil in an ammonium salt solution for the first chemical treatment, and after washing with water, placing the foil in a passivation solution 1 for passivation treatment;

[0007] (2) placing the passivated aluminum foil in an ammonium salt solution for a second chemical treatment, and after washing with water, placing the foil in passivation solution 2 for passivation treatment;

[0008] (3) washing the passivated aluminum foil with water and then performing heat treatment, cooling it and then placing it in an ammonium salt solution for a third chemical treatment, washing it with water, and drying it;

[0009] The passivation solution 1 is composed of the following components in percentage by weight: 3wt%-10wt% phosphoric acid, 0.001wt%-0.002wt% polystyrene sulfonic acid, and the rest is pure water;

[0010] The passivation solution 2 is composed of the following components in percentage by weight: 3wt%-10wt% phosphoric acid, 0.003wt%-0.005wt% hexadecyltrimethylammonium bromide, and the rest is pure water.

[0011] Furthermore, the temperature of the first chemical treatment in step (1) is 75-90° C. and the time is 5-15 min.

[0012] Furthermore, the temperature of the passivation treatment in step (1) is 50-70°C and the time is 1-5 minutes.

[0013] Furthermore, the temperature of the second chemical treatment in step (2) is 75-90° C. and the time is 1-10 min.

[0014] Furthermore, the temperature of the passivation treatment in step (2) is 50-70° C. and the time is 1-5 min.

[0015] Furthermore, the heat treatment in step (3) is performed at a temperature of 450-550° C. and for a time of 1-5 min.

[0016] Furthermore, the temperature of the third chemical treatment in step (3) is 75-90° C. and the time is 1-10 min.

[0017] Furthermore, the concentration of the ammonium salt solution in steps (1) and (2) is 10wt%-25wt%.

[0018] Furthermore, the concentration of the ammonium salt solution in step (3) is 10wt%-20wt%.

[0019] Furthermore, the ammonium salt is one or more of dodecyltrimethylammonium bromide, ammonium dodecyl alcohol ether sulfate, ammonium dihydrogen phosphate, ammonium adipate, ammonium citrate, and ammonium oxalate.

[0020] Furthermore, the drying temperature is 200°C.

[0021] Beneficial effects of the present invention:

[0022] The aluminum foil obtained by the experimental method of the present invention is formed at a rated voltage of 21V or 143V, and its withstand voltage and capacity can be maintained at normal levels. In addition, its hydration resistance is relatively excellent and can meet the test requirements of hydration performance.

[0023] The invention can significantly improve the hydration resistance of the aluminum oxide film by adding polystyrene sulfonic acid and hexadecyltrimethylammonium bromide into the passivation solution.

[0024] Compared with the prior art, the low-voltage corrosion foil formation process of the present invention not only ensures that the capacity and voltage of the aluminum foil are at normal levels, but also improves the hydration resistance of the aluminum foil. DETAILED DESCRIPTION

[0025] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0026] Example 1: (1) The corroded foil was placed in a 20 wt% ammonium adipate solution, and subjected to a first chemical treatment at 75°C for 5 min, followed by water washing, and then placed in a passivation solution 1, and subjected to a passivation treatment at 50°C for 1 min, wherein the composition of the passivation solution 1 was 3 wt% phosphoric acid, 0.001 wt% polystyrene sulfonic acid, and the remainder was pure water;

[0027] (2) placing the passivated aluminum foil in a 15wt% ammonium citrate solution, performing a second chemical treatment at 90°C for 6 minutes, then washing with water, and then placing it in passivation solution 2 for passivation treatment at 70°C for 2 minutes, wherein the composition of passivation solution 2 is 10wt% phosphoric acid, 0.005wt% hexadecyltrimethylammonium bromide, and the rest is pure water;

[0028] (3) The passivated aluminum foil was washed with water and then heat treated at 450°C for 1 min. After cooling, it was placed in a 10wt% ammonium oxalate solution at 75°C for a third chemical treatment for 3 min, washed with water, and dried at 200°C.

[0029] Example 2: (1) The corroded foil was placed in a 20 wt % ammonium adipate solution, and subjected to a first chemical treatment at 80° C. for 7 min, followed by water washing, and then placed in a passivation solution 1, and subjected to a passivation treatment at 60° C. for 3 min, wherein the composition of the passivation solution 1 was 7 wt % phosphoric acid, 0.001 wt % polystyrene sulfonic acid, and the remainder was pure water;

[0030] (2) placing the passivated aluminum foil in a 15wt% ammonium citrate solution, performing a second chemical treatment at 80°C for 5 minutes, then washing with water, and then placing it in passivation solution 2 for passivation treatment at 60°C for 3 minutes, wherein the composition of passivation solution 2 is 7wt% phosphoric acid, 0.004wt% hexadecyltrimethylammonium bromide, and the rest is pure water;

[0031] (3) The passivated aluminum foil was washed with water and then heat treated at 500°C for 1 min. After cooling, it was placed in a 15wt% ammonium oxalate solution at 80°C for a third chemical treatment for 5 min, washed with water, and dried at 200°C.

[0032] Example 3: (1) The corroded foil was placed in a 20 wt % ammonium adipate solution and subjected to a first chemical treatment at 90° C. for 6 min, followed by water washing, and then placed in a passivation solution 1 and subjected to a passivation treatment at 70° C. for 2 min, wherein the composition of the passivation solution 1 was 10 wt % phosphoric acid, 0.002 wt % polystyrene sulfonic acid, and the remainder was pure water;

[0033] (2) placing the passivated aluminum foil in a 10 wt% ammonium citrate solution, performing a second chemical treatment at 75°C for 8 min, then washing with water, and then placing it in passivation solution 2 for passivation treatment at 50°C for 2 min, wherein the composition of passivation solution 2 is 3 wt% phosphoric acid, 0.003 wt% hexadecyltrimethylammonium bromide, and the rest is pure water;

[0034] (3) The passivated aluminum foil was washed with water and then heat treated at 550°C for 2 min. After cooling, it was placed in a 15 wt% ammonium oxalate solution at 90°C for a third chemical treatment for 10 min. It was then washed with water and dried at 200°C.

[0035] Comparative Example 1: The difference from Example 2 is that the passivation solution 1 does not contain polystyrene sulfonic acid, and the remaining steps are the same as Example 2. The specific steps are as follows:

[0036] (1) The corroded foil was placed in a 20 wt% ammonium adipate solution and subjected to a first chemical treatment at 80°C for 7 min, followed by water washing, and then placed in a passivation solution 1 and subjected to a passivation treatment at 60°C for 3 min, wherein the composition of the passivation solution 1 was 7 wt% phosphoric acid and the remainder was pure water;

[0037] (2) placing the passivated aluminum foil in a 15wt% ammonium citrate solution, performing a second chemical treatment at 80°C for 5 minutes, then washing with water, and then placing it in passivation solution 2 for passivation treatment at 60°C for 3 minutes, wherein the composition of passivation solution 2 is 7wt% phosphoric acid, 0.004wt% hexadecyltrimethylammonium bromide, and the rest is pure water;

[0038] (3) The passivated aluminum foil was washed with water and then heat treated at 500°C for 1 min. After cooling, it was placed in a 15wt% ammonium oxalate solution at 80°C for a third chemical treatment for 5 min, washed with water, and dried at 200°C.

[0039] Comparative Example 2: The difference from Example 2 is that the passivation solution 2 does not contain hexadecyltrimethylammonium bromide, and the remaining steps are the same as Example 2. The specific steps are as follows:

[0040] (1) The corroded foil was placed in a 20wt% ammonium adipate solution and subjected to a first chemical treatment at 80°C for 7 minutes, followed by water washing, and then placed in a passivation solution 1 and subjected to a passivation treatment at 60°C for 3 minutes, wherein the composition of the passivation solution 1 was 7wt% phosphoric acid, 0.001wt% polystyrene sulfonic acid, and the remainder was pure water;

[0041] (2) placing the passivated aluminum foil in a 15 wt % ammonium citrate solution, performing a second chemical treatment at 80° C. for 5 min, then washing with water, and then placing it in passivation solution 2 for passivation treatment at 60° C. for 3 min, wherein the composition of passivation solution 2 is 7 wt % phosphoric acid and the rest is pure water;

[0042] (3) The passivated aluminum foil was washed with water and then heat treated at 500°C for 1 min. After cooling, it was placed in a 15wt% ammonium oxalate solution at 80°C for a third chemical treatment for 5 min, washed with water, and dried at 200°C.

[0043] Comparative Example 3: The difference from Example 2 is that the compositions of passivation solution 1 and passivation solution 2 are both 7wt% phosphoric acid, 0.001wt% polystyrene sulfonic acid, and the rest is pure water. The specific steps are as follows:

[0044] (1) The corroded foil was placed in a 20wt% ammonium adipate solution and subjected to a first chemical treatment at 80°C for 7 minutes, followed by water washing, and then placed in a passivation solution 1 and subjected to a passivation treatment at 60°C for 3 minutes, wherein the composition of the passivation solution 1 was 7wt% phosphoric acid, 0.001wt% polystyrene sulfonic acid, and the remainder was pure water;

[0045] (2) placing the passivated aluminum foil in a 15 wt% ammonium citrate solution, performing a second chemical treatment at 80°C for 5 min, then washing with water, and then placing it in passivation solution 2 for passivation treatment at 60°C for 3 min, wherein the composition of passivation solution 2 is 7 wt% phosphoric acid, 0.001 wt% polystyrene sulfonic acid, and the rest is pure water;

[0046] (3) The passivated aluminum foil was washed with water and then heat treated at 500°C for 1 min. After cooling, it was placed in a 15wt% ammonium oxalate solution at 80°C for a third chemical treatment for 5 min, washed with water, and dried at 200°C.

[0047] Comparative Example 4: The difference between Example 2 is that the compositions of passivation solution 1 and passivation solution 2 are both 7wt% phosphoric acid, 0.004wt% hexadecyltrimethylammonium bromide, and the rest is pure water. The specific steps are as follows:

[0048] (1) The corroded foil was placed in a 20wt% ammonium adipate solution and subjected to a first chemical treatment at 80°C for 7 minutes, followed by water washing, and then placed in a passivation solution 1 and subjected to a passivation treatment at 60°C for 3 minutes, wherein the composition of the passivation solution 1 was 7wt% phosphoric acid, 0.004wt% hexadecyltrimethylammonium bromide, and the remainder was pure water;

[0049] (2) placing the passivated aluminum foil in a 15wt% ammonium citrate solution, performing a second chemical treatment at 80°C for 5 minutes, then washing with water, and then placing it in passivation solution 2 for passivation treatment at 60°C for 3 minutes, wherein the composition of passivation solution 2 is 7wt% phosphoric acid, 0.004wt% hexadecyltrimethylammonium bromide, and the rest is pure water;

[0050] (3) The passivated aluminum foil was washed with water and then heat treated at 500°C for 1 min. After cooling, it was placed in a 15wt% ammonium oxalate solution at 80°C for a third chemical treatment for 5 min, washed with water, and dried at 200°C.

[0051] Comparative Example 5: The corroded foil was placed in a 15wt% ammonium adipate solution for chemical formation at 85°C for 8 min. After washing with water, the foil was treated at high temperature (500°C) for 2 min. The sample after high temperature treatment was placed in a 15wt% ammonium adipate solution for chemical formation at rated voltage at 85°C for 3 min. The foil was taken out, washed with water, and dried.

[0052] Comparative Example 6: The corrosion foil is subjected to six-stage chemical formation, the first stage chemical formation: 10wt% ammonium adipate solution, temperature 70℃, time 7min, after water washing, enter the second stage chemical formation: 8wt% ammonium adipate solution, temperature 70℃, time 6min, the third stage chemical formation: 5wt% ammonium adipate solution, temperature 70℃, time 8min, after water washing, the fourth stage chemical formation: 7wt% diammonium phosphate solution, temperature 70℃, time 10min, after water washing, the fifth stage chemical formation: 5wt% diammonium phosphate solution, temperature 70℃, time 12min, after water washing, the sixth stage chemical formation: 3wt% diammonium phosphate solution, temperature 70℃, time 15min;

[0053] The latter: 2wt% diammonium phosphate solution, temperature 80℃, time 12min, after water washing, enter into 7wt% phosphoric acid solution, time 5min, after water washing, high temperature (500℃) treatment for 1.5min;

[0054] The second step: 3wt% diammonium phosphate solution, temperature 70°C, time 5min;

[0055] The last three: 1wt% diammonium dihydrogen phosphate solution, temperature 70℃, time 5.5min, washed with water and then dried.

[0056] Performance Testing

[0057] The formation was carried out at rated voltages of 21V and 143V, and their performance was measured.

[0058] Specific volume: measured using a specific volume tester according to EIAJ RC-2364A standard method;

[0059] Hydration resistance: The samples obtained in the examples and comparative examples were kept in pure water at 100° C. for 1 hour, and the voltage rise time and reaching voltage were measured according to the Tr / Vt test method.

[0060] Table 1 Performance test processing

[0061]

[0062] Data analysis shows that from Examples 1-3 in Table 1, it can be seen that the aluminum foil obtained by the low-voltage corrosion foil formation process of the present invention can maintain its withstand voltage and capacity at normal levels when formed at a rated voltage of 21V or 143V, and its hydration resistance is relatively excellent.

[0063] It can be seen from Example 2 and Comparative Examples 1 and 2 in Table 1 that the addition of polystyrene sulfonic acid and hexadecyltrimethylammonium bromide to the passivation solution can significantly improve the hydration resistance of the aluminum oxide film. This is mainly because the two can act as corrosion inhibitors to prevent the phosphoric acid treatment process from being too strong, resulting in a crystalline oxide layer inside the oxide film and even damaging the aluminum substrate.

[0064] It can be seen from Example 2 and Comparative Examples 1, 2, 3, and 4 in Table 1 that adding polystyrene sulfonic acid and hexadecyltrimethylammonium bromide to the passivation solution can further improve the microstructure of the oxide layer and enhance the stability of the aluminum oxide film; and the two can together further enhance the hydration resistance of the aluminum foil.

[0065] It can be seen from Example 2 and Comparative Examples 4 and 5 in Table 1 that, compared with the prior art, the present invention significantly improves the hydration resistance of the aluminum foil while ensuring the pressure resistance and specific volume of the aluminum foil.

[0066] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

Claims

1. A low-pressure corrosion foil formation process, characterized in that: The following steps are involved: (1) Place the corroded foil in an ammonium salt solution for the first chemical treatment, and after washing with water, place it in the passivation solution 1 for passivation treatment; (2) placing the passivated aluminum foil in an ammonium salt solution for a second chemical treatment, and then washing it with water and placing it in passivation solution 2 for passivation treatment; (3) The passivated aluminum foil is washed with water and then heat-treated. After cooling, it is placed in an ammonium salt solution for a third chemical treatment, washed with water, and dried. The passivation solution 1 is composed of the following components in percentage by weight: 3wt%-10wt% phosphoric acid, 0.001wt%-0.002wt% polystyrene sulfonic acid, and the rest is pure water; The passivation solution 2 is composed of the following components in percentage by weight: 3 wt % to 10 wt % of phosphoric acid, 0.003 wt % to 0.005 wt % of hexadecyltrimethylammonium bromide, and the remainder is pure water.

2. The low-pressure corrosion foil forming process according to claim 1, characterized in that: The temperature of the first chemical conversion treatment in step (1) is 75-90° C. and the time is 5-15 minutes.

3. The low-pressure corrosion foil forming process according to claim 1, characterized in that: The temperature of the passivation treatment in step (1) is 50-70°C and the time is 1-5 minutes.

4. The low-pressure corrosion foil forming process according to claim 1, characterized in that: The temperature of the second chemical formation treatment in step (2) is 75-90°C and the time is 1-10 minutes.

5. The low-pressure corrosion foil forming process according to claim 1, characterized in that: The temperature of the passivation treatment in step (2) is 50-70°C and the time is 1-5 minutes.

6. The low-pressure corrosion foil forming process according to claim 1, characterized in that: The heat treatment temperature in step (3) is 450-550°C and the time is 1-5 minutes.

7. The low-pressure corrosion foil forming process according to claim 1, characterized in that: The temperature of the third chemical formation treatment in step (3) is 75-90°C and the time is 1-10 minutes.

8. The low-pressure corrosion foil forming process according to claim 1, characterized in that: The concentration of the ammonium salt solution in steps (1) and (2) is 10wt%-25wt%; the concentration of the ammonium salt solution in step (3) is 10wt%-20wt%.

9. The low-pressure corrosion foil forming process according to claim 1, characterized in that: The ammonium salt is one or more of dodecyltrimethylammonium bromide, ammonium adipate, ammonium lauryl ether sulfate, ammonium dihydrogen phosphate, ammonium citrate, and ammonium oxalate.

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