Formation method for sintered aluminum foil

Abstract

The invention provides a formation method for sintered aluminum foil, which comprises the following steps: the sintered aluminum foil is put into a solution containing a blocking agent for water boiling treatment, and the blocking agent is used for forming a passive film on the surface of the sintered aluminum foil; and performing formation treatment on the sintered aluminum foil. The method can avoid pore channel blockage of the sintered aluminum foil, so that the capacity of the sintered aluminum foil after formation treatment is improved, and the performance of the sintered aluminum foil is improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of electrode foil, and in particular to a formation method for sintering aluminum foil. Background Art

[0002] Sintered aluminum foil is an electrode foil produced by sintering aluminum powder. It significantly increases the capacity of anode foil used in aluminum electrolytic capacitors. Chemical conversion treatment is an essential and critical step in the electrode foil production process. However, traditional chemical conversion treatment techniques can adversely affect the performance of sintered aluminum foil, such as its capacity. Summary of the Invention

[0003] The present disclosure provides a formation method for sintering aluminum foil.

[0004] The present disclosure provides a chemical formation method for sintered aluminum foil, comprising: placing the sintered aluminum foil in a solution containing a blocking agent for boiling, wherein the blocking agent is used to form a passivation film on the surface of the sintered aluminum foil; and performing a chemical formation treatment on the sintered aluminum foil.

[0005] In some embodiments, before performing the chemical conversion treatment on the sintered aluminum foil, the method further includes: performing a first heat treatment on the sintered aluminum foil after the water boiling treatment.

[0006] In some embodiments, performing a chemical conversion treatment on the sintered aluminum foil includes: performing a chemical conversion treatment on the sintered aluminum foil after the first heat treatment using a chemical conversion solution containing phosphoric acid.

[0007] In some embodiments, the blocking agent includes one or more of nitrate, borate, alginate, silicate and chromate, and the mass concentration of the blocking agent is 0.1% to 10%.

[0008] In some embodiments, the boiling temperature is 80° C. to 98° C., and the boiling time is 1 min to 20 min.

[0009] In some embodiments, the temperature of the first heat treatment is 300° C. to 550° C., and the time of the first heat treatment is 1 min to 5 min.

[0010] In some embodiments, the chemical conversion liquid comprises boric acid, phosphoric acid, ammonium pentaborate, and citric acid, wherein the mass concentration of boric acid is 1% to 10%, the mass concentration of phosphoric acid is 0.01% to 0.1%, the mass concentration of ammonium pentaborate is 0.5% to 5%, and the mass concentration of citric acid is 0.1% to 3%.

[0011] In some embodiments, the sintered aluminum foil after the first heat treatment is subjected to a chemical formation treatment, including: performing a multi-stage segmented chemical formation treatment on the sintered aluminum foil after the first heat treatment, wherein the temperature of the chemical formation treatment is 70°C to 90°C, and the voltage of the chemical formation treatment increases step by step in the range of 400V to 700V.

[0012] In some embodiments, before placing the sintered aluminum foil in a solution containing a blocking agent for boiling, the method further comprises: subjecting the sintered aluminum foil to an acid treatment or an alkali treatment.

[0013] In some embodiments, the sintered aluminum foil is subjected to an acid treatment or an alkali treatment, comprising: using one or more of H2O2, H2SO4 and HNO3 to perform an acid treatment on the sintered aluminum foil; or using one or two of NaOH and ammonia water to perform an alkali treatment on the sintered aluminum foil; wherein the mass concentration of the solution used for the acid treatment or the alkali treatment of the sintered aluminum foil is 0.1% to 10%, the temperature is 20°C to 60°C, and the time is 10s to 10min.

[0014] In some embodiments, after the sintered aluminum foil is subjected to a chemical formation treatment, the method further includes: sequentially performing a passivation treatment, a second heat treatment, a repair chemical formation, a post-treatment, and drying on the sintered aluminum foil after the chemical formation treatment.

[0015] The present invention adds a pre-forming step when performing a forming treatment on the sintered aluminum foil, and puts the sintered aluminum foil into a solution containing a blocking agent and performs a water boiling treatment, so that the blocking agent reacts with the aluminum powder of the sintered aluminum foil to form a passivation film on the surface of the sintered aluminum foil, which can inhibit the contact between water and aluminum powder and avoid excessive generation of a hydrated oxide film, thereby avoiding clogging of the pores of the sintered aluminum foil, which is beneficial to increasing the capacity of the sintered aluminum foil after the forming treatment and improving the performance of the sintered aluminum foil. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic flow chart of a formation method for sintering aluminum foil according to an embodiment of the present disclosure is shown.

[0017] Figure 2 A schematic diagram comparing the pore size distribution of the aluminum foil of an embodiment of the present disclosure and a comparative example is shown. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the technical solution of the present disclosure, the technical solution of the present disclosure is described in detail below with reference to the accompanying drawings.

[0019] Example embodiments will be described more fully hereinafter with reference to the accompanying drawings, but the example embodiments may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of this disclosure to those skilled in the art.

[0020] In the absence of conflict, the various embodiments of the present disclosure and the various features therein may be combined with each other.

[0021] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0022] The terms used herein are used only to describe specific embodiments and are not intended to limit the present disclosure. As used herein, the singular forms "a," "an," and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It will also be understood that when the terms "comprising" and / or "made of" are used in this specification, the presence of the features, wholes, steps, operations, elements, and / or components is specified, but the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or groups thereof is not excluded.

[0023] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted as having an idealized or overly formal meaning unless expressly defined as such herein.

[0024] Traditional chemical conversion processes, including high-pressure chemical conversion, are suitable for etching the tunnel pore structure of aluminum foil, where the tunnel pore size is approximately 1-2 microns. In contrast, sintered aluminum foil, formed by the accumulation of aluminum powder, has gaps between each powder less than 1 micron, for example, several hundred nanometers. Using high-pressure chemical conversion to convert sintered aluminum foil can easily cause the pores of the sintered aluminum foil to become clogged by excessive oxide film growth, thus affecting the capacity of the finished foil. Smaller pores also increase the time it takes for the conversion liquid to enter the sintered aluminum foil during the conversion process, making it difficult to increase the pressure and requiring more stages of conversion. Smaller gaps also impair the effectiveness of phosphoric acid and ammonium dihydrogen phosphate treatments, resulting in poor water resistance in the sintered aluminum foil.

[0025] The embodiments of the present disclosure provide a chemical formation method for sintering aluminum foil, such as Figure 1 As shown, the formation method includes: S1. Putting the sintered aluminum foil into a solution containing a blocking agent for boiling, wherein the blocking agent is used to form a passivation film on the surface of the sintered aluminum foil.

[0026] S2. performing chemical conversion treatment on the sintered aluminum foil.

[0027] In the embodiment of the present disclosure, a pre-formation step is added when the sintered aluminum foil is subjected to a formation treatment. The sintered aluminum foil is placed in a solution containing a blocking agent and boiled in water, so that the blocking agent reacts with the aluminum powder of the sintered aluminum foil to form a passivation film on the surface of the sintered aluminum foil. This can inhibit the degree of contact between water and aluminum powder, avoid excessive generation of a hydrated oxide film, and thus avoid clogging of the pores of the sintered aluminum foil.

[0028] In some embodiments, before subjecting the sintered aluminum foil to the chemical conversion treatment, the chemical conversion method further includes: subjecting the sintered aluminum foil to a first heat treatment after the water boiling treatment. In some embodiments, by adding the first heat treatment step between the water boiling treatment and the chemical conversion treatment, the transformation of the hydrated oxide film to the crystalline oxide film is accelerated, the volume fraction of the hydrated oxide film is reduced, pore blockage is further avoided, and the pressure increase difficulty of the chemical conversion treatment is reduced.

[0029] In some embodiments, the blocking agent includes one or more of nitrate, borate, alginate, silicate and chromate, and the mass concentration of the blocking agent is 0.1% to 10%. In some embodiments, taking into account the difficulty of cleaning, one or more of nitrate, borate and alginate are preferably adopted. In some embodiments, the salt of these substances may include ammonium salt. In some embodiments, the mass concentration of the blocking agent may be 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or any suitable value therebetween. If the concentration of the blocking agent is too low, the effect of suppressing the generation of the hydrated oxide film is relatively limited. If the concentration of the blocking agent is too high, the hydrated oxide film may not be formed, and the lack of the hydrated oxide film may cause the pressure to increase in the subsequent formation process.

[0030] In some embodiments, the temperature of the water boiling treatment is 80°C to 98°C, and the water boiling treatment time is 1 min to 20 min. In some embodiments, the water boiling treatment temperature is 80°C, 85°C, 90°C, 95°C, 98°C, or any suitable value therebetween. If the water boiling treatment temperature is too low, too little hydration film will be formed, and subsequent formation will consume a lot of power and take a long time; if the water boiling treatment temperature is too high, the hydration film will clog the pores and the capacity will decrease. In some embodiments, the water boiling treatment time is 1 min, 5 min, 10 min, 15 min, 20 min, or any suitable value therebetween. If the time is too long, the hydration film will clog the pores and the capacity will decrease; if the time is too short, too little hydration film will be formed, and subsequent formation will consume a lot of power and take a long time.

[0031] In some embodiments, the temperature of the first heat treatment is 300°C to 550°C, and the duration of the first heat treatment is 1 minute to 5 minutes. In some embodiments, the first heat treatment is performed in a muffle furnace. In some embodiments, the temperature of the first heat treatment is 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, or any suitable value therebetween. If the temperature of the first heat treatment is too low, the rate of transformation of the hydrated oxide film to the crystalline oxide film is too slow, reducing the efficiency of the heat treatment. If the temperature of the first heat treatment is too high, it may cause undesirable changes or excessive growth of the oxide layer on the surface of the aluminum foil, and may even cause the aluminum foil itself to soften or deform. In some embodiments, the duration of the first heat treatment is 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, or any suitable value therebetween. If the duration of the first heat treatment is too short, the degree of transformation of the hydrated oxide film to the crystalline oxide film may be insufficient. If the duration of the first heat treatment is too long, it may lead to unnecessary grain coarsening or other negative effects, such as increased oxidation.

[0032] In some embodiments, the chemical formation method further includes: before the water boiling treatment, the sintered aluminum foil is subjected to an acid treatment or an alkali treatment. By using an acid or alkali treatment before the aluminum foil is formed, the oxide film and part of the small-particle aluminum powder on the surface of the sintered aluminum foil are dissolved, so that the pores of the aluminum powder are increased. Generally, the traditional corroded aluminum foil has tunnel holes, and it is difficult for the oxide film to be formed to block the pores. The aluminum foil to be formed in the present disclosure is a laminated foil formed by the accumulation of aluminum powder, and its pores are pores formed by the accumulation of spherical aluminum powder, which are smaller than those of the general corroded aluminum foil. In addition to the traditional function of removing the oxide film, the acid treatment or alkali treatment used in the present disclosure also has the function of dissolving smaller particles of aluminum powder. The gaps around the small-particle aluminum powder are smaller and will be completely blocked after formation, and will not contribute to the capacity. Therefore, the acid treatment or alkali treatment is used to remove this part of the aluminum powder in advance to expand the pores, which can achieve the effect of increasing the capacity.

[0033] In some embodiments, the acid treatment comprises treatment with one or more of H2O2, H2SO4, and HNO3. In some embodiments, the alkaline treatment comprises treatment with one or both of NaOH and ammonia solution. In some embodiments, the mass concentration of the solution used for the acid or alkaline treatment is 0.1% to 10%, for example, 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any suitable value therebetween. If the concentration is too low, the removal of small particles of aluminum powder is relatively limited; if the concentration is too high, a large amount of aluminum powder will dissolve, reducing the capacity of the aluminum foil. In some embodiments, the temperature of the acid or alkaline treatment is 20°C to 60°C, for example, 20°C, 30°C, 40°C, 50°C, 60°C, or any suitable value therebetween. If the temperature is too low, the efficiency of removing small particles of aluminum powder will be reduced; if the temperature is too high, excessive corrosion will occur, even damaging the aluminum foil substrate, causing the material to become thinner or pitting. In some embodiments, the acid treatment or alkali treatment time is from 10 seconds to 10 minutes, for example, 10 seconds, 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, or any suitable value therebetween. If the time is too short, the surface cannot be thoroughly cleaned and small particles of aluminum powder cannot be removed. If the time is too long, excessive corrosion may occur, which may also damage the quality of the aluminum foil.

[0034] In some embodiments, performing a chemical conversion treatment on the sintered aluminum foil includes: performing a chemical conversion treatment on the sintered aluminum foil after the first heat treatment using a chemical conversion solution containing phosphoric acid.

[0035] In the embodiment of the present disclosure, phosphoric acid, such as extremely dilute phosphoric acid, is added to the conversion liquid, which can form aluminum phosphate on the surface of the sintered aluminum foil, thereby enhancing the boiling resistance of the sintered aluminum foil after the conversion treatment.

[0036] In some embodiments, the conversion liquid used in the conversion treatment includes, by mass concentration, 1% to 10% boric acid, 0.01% to 0.1% phosphoric acid, 0.5% to 5% ammonium pentaborate, and 0.1% to 3% citric acid. Adding extremely dilute phosphoric acid to the conversion liquid can generate aluminum phosphate on the surface of the aluminum foil, enhancing the final boiling resistance of the sintered aluminum foil after conversion. In some embodiments, the concentration of phosphoric acid in the conversion liquid is 0.01%, 0.05%, 0.1%, or any suitable value therebetween. The oxide film is not dense enough before conversion is complete, and high phosphoric acid concentrations can corrode the incompletely formed oxide film. Therefore, extremely dilute phosphoric acid is used to pre-generate trace amounts of aluminum phosphate at different depths of the oxide film during the conversion process, further improving the final boiling resistance.

[0037] In some embodiments, the formation process includes a multi-stage formation process, wherein the temperature of the formation process is 70° C. to 90° C., and the voltage of the formation process is 400 V to 700 V, with the voltage increasing step by step. In some embodiments, the formation process uses four to seven stages (e.g., six stages), but the present disclosure is not limited thereto.

[0038] In some embodiments, the chemical formation method further comprises: sequentially performing a passivation treatment, a second heat treatment, a repair chemical formation, a post-treatment, and drying on the sintered aluminum foil after the chemical formation treatment. In some embodiments, the solution used for the passivation treatment is a phosphoric acid solution with a mass concentration of 3% to 10%, the passivation treatment temperature is 50°C to 75°C, and the passivation treatment time is 1 min to 20 min. In some embodiments, the temperature of the second heat treatment is 300°C to 550°C, and the second heat treatment time is 1 min to 5 min. In some embodiments, the solution used for the repair chemical formation is a boric acid solution with a mass concentration of 1% to 10%, and the repair chemical formation temperature is 70°C to 90°C. In some embodiments, the solution used for the post-treatment is ammonium dihydrogen phosphate with a mass concentration of 1% to 5%, the post-treatment temperature is 50°C to 75°C, and the post-treatment time is 1 min to 10 min. In some embodiments, the drying temperature is 150°C to 300°C, and the drying time is 1 min to 3 min.

[0039] The present disclosure will be better understood with reference to the following specific embodiments.

[0040] Example 1 1. Place the treated sintered aluminum foil in a 1% ammonium alginate solution and boil it at 90°C for 10 minutes, then place it in a muffle furnace at 500°C for 2 minutes; 2. The sintered aluminum foil after high-temperature treatment is placed in a forming solution at a temperature of 80°C and subjected to six-stage forming. The forming voltage is gradually increased (400V, 425V, 450V, 475V, 500V and 520V respectively), the boric acid content is gradually increased (1%, 3%, 5%, 7%, 9% and 10% respectively), and the ammonium pentaborate content is gradually reduced (5%, 4%, 3%, 2%, 1% and 0.5% respectively). Phosphoric acid is added in the first three stages and the content is gradually reduced (0.1%, 0.05% and 0.01% respectively). Citric acid is used to adjust the pH to about 5. 3. The sintered aluminum foil after chemical formation was placed in a phosphoric acid solution with a temperature of 60°C and a concentration of 5% for passivation treatment for 12 minutes, then heat treated at 450°C for 2 minutes, and then placed in a boric acid solution with a temperature of 80°C and a concentration of 8% for repair chemical formation. Finally, it was immersed in a 3% ammonium dihydrogen phosphate solution at 50°C for 5 minutes, taken out and placed in an oven at 200°C for drying for 2 minutes.

[0041] Example 2 1. Treat the sintered aluminum foil in 0.5% nitric acid solution at 30°C for 2 min; 2. Place the treated sintered aluminum foil in a 1% ammonium alginate solution and boil it at 90°C for 10 minutes, then place it in a muffle furnace at 500°C for 2 minutes; 3. The sintered aluminum foil after high-temperature treatment is placed in a forming solution at a temperature of 80°C and subjected to six-stage forming. The forming voltage is gradually increased (400V, 425V, 450V, 475V, 500V and 520V respectively), the boric acid content is gradually increased (1%, 3%, 5%, 7%, 9% and 10% respectively), and the ammonium pentaborate content is gradually reduced (5%, 4%, 3%, 2%, 1% and 0.5% respectively). Phosphoric acid is added in the first three stages and the content is gradually reduced (0.1%, 0.05% and 0.01% respectively). Citric acid is used to adjust the pH to about 5. 4. The sintered aluminum foil after chemical formation was placed in a phosphoric acid solution with a temperature of 60°C and a concentration of 5% for passivation treatment for 12 minutes, followed by heat treatment at 450°C for 2 minutes, and then placed in a boric acid solution with a temperature of 80°C and a concentration of 8% for repair chemical formation. Finally, it was immersed in a 3% ammonium dihydrogen phosphate solution at 50°C for 5 minutes, taken out and placed in an oven at 200°C for drying for 2 minutes.

[0042] Example 3 1. Treat the sintered aluminum foil in 0.1% nitric acid solution at 20°C for 10 minutes; 2. Place the treated sintered aluminum foil in 0.1% ammonium alginate solution at 80°C for 20 minutes, and then place it in a muffle furnace at 550°C for 1 minute; 3. The sintered aluminum foil after high-temperature treatment is placed in a forming solution at a temperature of 70°C for six-stage forming. The forming voltage is gradually increased (400V, 425V, 450V, 475V, 500V and 520V respectively), the boric acid content is gradually increased (1%, 3%, 5%, 7%, 9% and 10% respectively), and the ammonium pentaborate content is gradually reduced (5%, 4%, 3%, 2%, 1% and 0.5% respectively). Phosphoric acid is added in the first three stages and the content is gradually reduced (0.1%, 0.05% and 0.01% respectively). Citric acid is used to adjust the pH to about 5. 4. Place the sintered aluminum foil after chemical formation in a 3% phosphoric acid solution at 50°C for passivation treatment for 20 minutes, then heat treat it at 300°C for 5 minutes, and then place it in a 10% boric acid solution at 70°C for repair formation. Finally, soak it in a 1% ammonium dihydrogen phosphate solution at 75°C for 1 minute, take it out and place it in a 150°C oven to dry for 3 minutes.

[0043] Example 4 1. Treat the sintered aluminum foil in 10% nitric acid solution at 60°C for 10 seconds; 2. Place the treated sintered aluminum foil in a 10% ammonium alginate solution at 98°C for 10 minutes, and then place it in a muffle furnace at 300°C for 5 minutes; 3. The sintered aluminum foil after high-temperature treatment is placed in a forming solution at a temperature of 90°C for six-stage forming. The forming voltage is gradually increased (400V, 425V, 450V, 475V, 500V and 520V respectively), the boric acid content is gradually increased (1%, 3%, 5%, 7%, 9% and 10% respectively), and the ammonium pentaborate content is gradually reduced (5%, 4%, 3%, 2%, 1% and 0.5% respectively). Phosphoric acid is added in the first three stages and the content is gradually reduced (0.1%, 0.05% and 0.01% respectively). Citric acid is used to adjust the pH to about 5. 4. The sintered aluminum foil after chemical formation was placed in a phosphoric acid solution with a temperature of 75°C and a concentration of 10% for passivation treatment for 1 min, followed by heat treatment at 550°C for 1 min, and then placed in a boric acid solution with a temperature of 90°C and a concentration of 1% for repair chemical formation. Finally, it was immersed in a 5% ammonium dihydrogen phosphate solution at 60°C for 9 min, and then taken out and placed in a 300°C oven for drying for 1 min.

[0044] Comparative Example 1 1. Boil the treated sintered aluminum foil in pure water at 90°C for 10 min; 2. The sintered aluminum foil after high-temperature treatment was placed in a forming solution at a temperature of 80°C and subjected to six-stage forming. The forming voltage was gradually increased (400V, 425V, 450V, 475V, 500V and 520V respectively), the boric acid content was gradually increased (1%, 3%, 5%, 7%, 9% and 10% respectively), and the ammonium pentaborate content was gradually decreased (5%, 4%, 3%, 2%, 1% and 0.5% respectively). Citric acid was used to adjust the pH to about 5. 3. The sintered aluminum foil after chemical formation was placed in a phosphoric acid solution with a temperature of 60°C and a concentration of 5% for passivation treatment for 12 minutes, then heat treated at 450°C for 2 minutes, and then placed in a boric acid solution with a temperature of 80°C and a concentration of 8% for repair chemical formation. Finally, it was immersed in a 3% ammonium dihydrogen phosphate solution at 50°C for 5 minutes, taken out and placed in an oven at 200°C for drying for 2 minutes.

[0045] The performance parameters of the aluminum foils obtained in Examples 1-4 and Comparative Example 1 were tested using conventional industry standard testing methods, see Table 1.

[0046] Table 1 As can be seen from Table 1 above, compared with Comparative Example 1, Examples 1-4 have increased pressure resistance, increased specific volume, reduced pressure rise time, and reduced 1h water boiling pressure rise time. Figure 2 , shows the pore size distribution of the aluminum foil of Example 2 and Comparative Example 1, where the horizontal axis is pore size and the vertical axis is the proportion of pores with corresponding pore sizes. By improving the steps of the examples, the pores are increased and the capacity decay caused by pore blockage is reduced.

[0047] Table 2 shows the parameter test results of Example 2 and Examples 5-7. The only difference between Examples 5-7 and Example 2 is the type of blocking agent used. Example 5 uses ammonium nitrate as the blocking agent, Example 6 uses ammonium borate as the blocking agent, and Example 7 uses a 1:1 ratio of ammonium nitrate and ammonium borate as the blocking agent.

[0048] Table 2 Table 3 shows the parameter test results of Example 2 and Examples 8-15, wherein the difference between Examples 8-15 and Example 2 is only the different concentrations of the blocking agents used.

[0049] Table 3 If the concentration of the blocking agent is too low, its effect of inhibiting the formation of hydrated oxide film will be relatively limited. If the concentration of the blocking agent is too high, the hydrated oxide film will not be formed, and the lack of hydrated oxide film will make it difficult to increase the pressure during the subsequent formation process.

[0050] Table 4 shows the parameter test results for Example 2, Examples 16-19, and Comparative Example 2. Examples 16-18 differ from Example 2 only in the type of acid or base used in the first acid-base treatment: Example 16 uses sulfuric acid, Example 17 uses aqueous ammonia, and Example 18 uses NaOH. Example 19 differs from Example 2 in that the conversion solution does not contain phosphoric acid; all other conditions are the same as those in Example 2. Comparative Example 2 differs from Example 2 in that the conversion treatment is performed directly after boiling, without the first heat treatment.

[0051] Table 4 It can be seen from Table 4 that when the conversion solution does not contain extremely dilute phosphoric acid, the various properties of the aluminum foil are reduced; when the first heat treatment is not performed, the various properties of the aluminum foil are reduced.

[0052] Example embodiments have been disclosed herein, and although specific terms are employed, they are used and should be interpreted only in a general illustrative sense and not for purposes of limitation. In some instances, it will be apparent to those skilled in the art that, unless otherwise expressly indicated, features, characteristics, and / or elements described in conjunction with a particular embodiment may be used alone or in combination with features, characteristics, and / or elements described in conjunction with other embodiments. Therefore, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the scope of the present disclosure as set forth in the appended claims.

Claims

1. A chemical formation method for sintering aluminum foil, characterized in that: include: placing the sintered aluminum foil in a solution containing a blocking agent for boiling, wherein the blocking agent is used to form a passivation film on the surface of the sintered aluminum foil; The sintered aluminum foil is subjected to chemical conversion treatment.

2. The chemical formation method according to claim 1, characterized in that Before the sintered aluminum foil is subjected to chemical treatment, it also includes: The sintered aluminum foil after the water boiling treatment is subjected to a first heat treatment.

3. The chemical formation method according to claim 2, characterized in that The sintered aluminum foil is subjected to chemical treatment, including: The sintered aluminum foil after the first heat treatment is subjected to a chemical conversion treatment using a chemical conversion solution containing phosphoric acid.

4. The chemical formation method according to any one of claims 1 to 3, characterized in that The blocking agent includes one or more of nitrate, borate, alginate, silicate and chromate, and the mass concentration of the blocking agent is 0.1% to 10%.

5. The chemical formation method according to any one of claims 1 to 3, characterized in that The boiling temperature is 80° C. to 98° C., and the boiling time is 1 min to 20 min.

6. The chemical formation method according to claim 2 or 3, characterized in that: The temperature of the first heat treatment is 300° C. to 550° C., and the time of the first heat treatment is 1 minute to 5 minutes.

7. The chemical formation method according to claim 3, characterized in that The chemical conversion liquid comprises boric acid, phosphoric acid, ammonium pentaborate and citric acid, wherein the mass concentration of boric acid is 1% to 10%, the mass concentration of phosphoric acid is 0.01% to 0.1%, the mass concentration of ammonium pentaborate is 0.5% to 5%, and the mass concentration of citric acid is 0.1% to 3%.

8. The chemical formation method according to claim 7, characterized in that The sintered aluminum foil after the first heat treatment is subjected to a chemical conversion treatment, including: The sintered aluminum foil after the first heat treatment is subjected to a multi-stage segmented chemical formation treatment, wherein the temperature of the chemical formation treatment is 70° C. to 90° C., and the voltage of the chemical formation treatment is gradually increased within the range of 400V to 700V.

9. The chemical formation method according to any one of claims 1 to 3, characterized in that: Before the sintered aluminum foil is placed in a solution containing a blocking agent for boiling, the following steps are also included: The sintered aluminum foil is subjected to acid treatment or alkali treatment.

10. The chemical formation method according to claim 7, characterized in that: Acid or alkali treatment of sintered aluminum foil, including: Acid-treating the sintered aluminum foil with one or more of H2O2, H2SO4, and HNO3; or Alkali treatment of sintered aluminum foil using one or both of NaOH and ammonia solution; The mass concentration of the solution used for the acid treatment or alkali treatment of the sintered aluminum foil is 0.1% to 10%, the temperature is 20° C. to 60° C., and the time is 10 seconds to 10 minutes.

11. The chemical formation method according to any one of claims 1 to 3, characterized in that: After the sintered aluminum foil is chemically treated, it also includes: The sintered aluminum foil after the chemical formation treatment is subjected to passivation treatment, second heat treatment, repair chemical formation, post-treatment and drying in sequence.

Images