A method for preparing an anti-corrosion film layer on the surface of an electrical material aluminum alloy

Abstract

The present application discloses a method for preparing an anticorrosion film layer on the surface of an electrical material aluminum alloy, which comprises the following steps in sequence: degreasing, alkaline etching, neutralization and decontamination, anodizing, sealing, water washing and drying; the anodizing liquid used in the anodizing step is a mixed compound liquid, which comprises hyperbranched polyester, sodium tannate and sulfuric acid, wherein the concentration of the hyperbranched polyester is 2-2.8 g / L, the concentration of the sodium tannate is 0.021-0.029 mol / L, and the concentration of the sulfuric acid is 0.05-0.07 mol / L. Sodium tannate and hyperbranched polyester are added to the anodizing liquid, and the synergistic effect of the two improves the deposition mode and compactness of the anodized film, so that the anticorrosion film layer formed on the surface of the electrical material aluminum alloy has excellent corrosion resistance and adhesion.

Description

Technical Field

[0001] The present application relates to electrical aluminum alloy materials, and in particular to a method for preparing an anti-corrosion film layer on the surface of an electrical aluminum alloy material. Background Art

[0002] Aluminum alloys, electrical materials, are widely used in power transmission, electronic equipment and other fields due to their excellent electrical conductivity and lightweight properties. However, the surface of aluminum alloys is susceptible to corrosion, which affects their service life and electrical properties. Therefore, the development of efficient anti-corrosion film preparation methods is of great significance for improving the corrosion resistance and extending the service life of aluminum alloy materials.

[0003] In order to improve the corrosion resistance of the aluminum alloy surface, the commonly used anodizing method is to immerse the aluminum alloy in an anodizing solution and generate a dense aluminum oxide film on the surface of the aluminum alloy through electrolysis. The anodizing solution is composed of sulfuric acid and oxalic acid.

[0004] The anodizing method can significantly improve the corrosion resistance of aluminum alloys to a certain extent, but there are still some defects in practical applications. First, the film layer generated by the traditional anodizing liquid has a low hardness and is easy to fall off, and the parameter control during the anodizing process is relatively complex and there are inevitable fluctuations, so the problem of uneven film thickness and density is also relatively common, which further reduces the overall protective effect of the film layer. As a result, the adhesion and anti-corrosion performance of the surface anti-corrosion film layer generated by the existing anodizing method for treating electrical material aluminum alloys cannot meet the application requirements of high-demand electrical environments. Summary of the invention

[0005] In order to meet the requirements for adhesion and anti-corrosion performance of anti-corrosion film layer on the surface of aluminum alloy in high-demand electrical environment, a method for preparing anti-corrosion film layer on the surface of electrical material aluminum alloy is provided.

[0006] The above first invention objective of the present invention is achieved through the following technical solutions:

[0007] A method for preparing an anticorrosive film layer on the surface of an electrical material aluminum alloy comprises the following steps in sequence: degreasing, alkali etching, neutralization and decontamination, anodizing, sealing, water washing and drying; the anodizing liquid used in the anodizing step is a mixed composite liquid, which comprises hyperbranched polyester, sodium tannate and sulfuric acid, wherein the concentration of the hyperbranched polyester is 2-2.8 g / L, the concentration of the sodium tannate is 0.021-0.029 mol / L, and the concentration of the sulfuric acid is 0.05-0.07 mol / L.

[0008] By adopting the above technical scheme, sodium tannate and hyperbranched polyester are added to the anodizing liquid, and the sodium tannate combines with the non-aluminum metal ions dissolved from the aluminum alloy in an acidic environment to prevent the non-aluminum metal ion hydroxide from combining and depositing into the anodized film. In addition, the sodium tannate can also repair tiny defects on the metal surface and promote the production of the oxide film, while improving the growth rate and density of the anodized film on the surface of the aluminum alloy.

[0009] Hyperbranched polyester can improve the deposition pattern of aluminum oxide and aluminum hydroxide complexes in the anodic oxide film and improve the corrosion resistance of the anodic oxide film. In addition, hyperbranched polyester can also reduce the activation energy of the reaction, assist the combination of sodium tannate with non-aluminum metal ions, and enhance the effect of sodium tannate, thereby making the anti-corrosion film layer formed on the surface of the electrical material aluminum alloy have excellent corrosion resistance and adhesion.

[0010] Optional: Anodizing current is 1.5~1.25A / dm 2 , the anodizing liquid temperature is 12°C, and the anodizing time is 35~42min.

[0011] By adopting the above technical solution, the anti-corrosion film layer formed on the surface of the obtained electrical material aluminum alloy has good corrosion resistance and adhesion.

[0012] Optionally, the hyperbranched ester is an acrylic acid-terminated modified hyperbranched polyester.

[0013] By adopting the above technical solution, the hyperbranched ester has a greater destructive effect on the hydrated ion layer around the metal ions, has a better effect on improving the deposition pattern of the aluminum oxide and aluminum hydroxide composite of the anodized film, and has better corrosion resistance of the anodized film.

[0014] Optional: The sealing liquid components in the sealing step include methyl silicate, siloxane, propylene glycol, and a surfactant, with the concentration of methyl silicate being 9.6~14.4g / L, the concentration of siloxane being 3.69~5.52g / L, the concentration of propylene glycol being 2.56~3.84g / L, and the concentration of surfactant being 0.64~0.96g / L.

[0015] By adopting the above technical scheme, propylene glycol plays a role in activating methyl silicate. The tannic acid in the anodized film can catalyze the breakage of Si-O in siloxane and catalyze the hydrolysis of methyl silicate, thereby making the silicate deposition in the pores of the anodized film denser and the combination with the anodized film more immersed, thereby improving the adhesion and anti-corrosion performance of the anti-corrosion film layer on the surface of the electrical material aluminum alloy.

[0016] Optionally: the sealing liquid component in the sealing step also includes triethanolamine.

[0017] By adopting the above technical scheme, triethanolamine can form a complex with residual aluminum ions in the pores of the anodized film, eliminate the residual aluminum ions and fill the pores of the oxide film, thereby improving the corrosion resistance of the oxide film. The addition of triethanolamine can also reduce the adsorption of the oxide film surface, thereby improving its corrosion resistance to corrosive media.

[0018] Optional: The surfactant is polyoxyethylene lauryl ether.

[0019] By adopting the above technical scheme, the effect of polyoxyethylene lauryl ether in the sealing liquid is still better at above 70°C, and it has a good dispersing effect on methyl silicate and siloxane in the sealing liquid. The obtained electrical material aluminum alloy surface anti-corrosion film layer has good adhesion and anti-corrosion performance.

[0020] Optional: The siloxane is 3-aminopropyltriethoxysilane.

[0021] By adopting the above technical solution, the surface roughness of the coating is significantly reduced and the hydrophobicity of the coating is improved, which effectively slows down the penetration of corrosive media. The resulting electrical material aluminum alloy surface anti-corrosion film layer has good anti-corrosion performance.

[0022] Optional: The sealing liquid temperature is 75~82℃ and the sealing treatment time is 35min.

[0023] By adopting the above technical solution, the anti-corrosion film layer on the surface of the electrical material aluminum alloy obtained under the process parameters has good anti-corrosion performance and high production efficiency.

[0024] In summary, this application has at least the following beneficial effects:

[0025] Sodium tannate and hyperbranched polyester are added to the anodizing liquid, and the two work synergistically to improve the deposition pattern and density of the anodized film, so that the anti-corrosion film layer formed on the surface of the electrical material aluminum alloy has excellent corrosion resistance and adhesion. DETAILED DESCRIPTION

[0026] raw material:

[0027] Acrylic acid, ε-caprolactone, stannous octoate, acetone, triethanolamine, propylene glycol p-hydroxyanisole, p-toluenesulfonic acid, methyl silicate, 3-aminopropyltriethoxysilane, methyltriethoxysilane, polyoxyethylene lauryl ether, and sodium dodecylbenzenesulfonate are commercially available industrial grade products;

[0028] Sodium tannate is prepared by preparing analytical grade tannic acid into a 0.01 mol / L aqueous solution, and then adding sodium hydroxide to adjust the pH to 7.0; sulfuric acid is a 52.2 wt % aqueous sulfuric acid solution, which is obtained by diluting commercially available concentrated sulfuric acid; sodium tannate and sulfuric acid are further diluted as needed during the subsequent preparation process, and the specific concentrations after dilution are shown below.

[0029] Preparation Example 1

[0030] A hyperbranched polyester, the preparation method of which is as follows:

[0031] S1: ε-caprolactone and dipentaerythritol were mixed in a molar ratio of 6:1, and then 0.12wt% of stannous octoate was added, and the mixture was reacted at 165°C for 8h under nitrogen protection to obtain a hyperbranched polyester matrix;

[0032] S2: Mix the hyperbranched polyester, acrylic acid, acetone, p-hydroxyanisole and p-toluenesulfonic acid in a mass ratio of 1:5.3:0.8:0.08:0.1, and react at 80° C. for 4.5 hours to obtain a reaction mass;

[0033] The reaction material was distilled under reduced pressure at a vacuum degree of 0.08 MPa for 30 min to obtain an acrylic acid-terminated hyperbranched polyester.

[0034] Preparation Example 2

[0035] A hyperbranched polyester, its preparation method is as follows:

[0036] S1: ε-caprolactone and dipentaerythritol were mixed in a molar ratio of 6:1, and 0.12 wt% of stannous octoate was added, and the mixture was reacted at 165° C. for 8 h under nitrogen protection to obtain a hyperbranched polyester.

[0037] Preparation Example 3

[0038] An anodic oxidation liquid comprises hyperbranched polyester, sodium tannate, sulfuric acid and water. The hyperbranched polyester is prepared in Example 1, and the concentration of the hyperbranched polyester is 2.4 g / L. The concentration of the sodium tannate is 0.025 mol / L; and the concentration of the sulfuric acid is 0.06 mol / L.

[0039] Preparation Example 4

[0040] An anodic oxidation liquid, which is different from Preparation Example 3 in that the hyperbranched polyester is prepared according to Preparation Example 2.

[0041] Preparation Example 5

[0042] An anodic oxidation liquid, which is different from Preparation Example 3 in that: the concentration of hyperbranched polyester is 1.2 g / L; the concentration of sodium tannate is 0.0125 mol / L; and the concentration of sulfuric acid is 0.03 mol / L.

[0043] Preparation Example 6

[0044] An anodic oxidation liquid, which is different from Preparation Example 3 in that: the concentration of hyperbranched polyester is 2 g / L; the concentration of sodium tannate is 0.021 mol / L; and the concentration of sulfuric acid is 0.05 mol / L.

[0045] Preparation Example 7

[0046] An anodic oxidation liquid, which is different from Preparation Example 3 in that: the concentration of hyperbranched polyester is 2.8 g / L; the concentration of sodium tannate is 0.029 mol / L; and the concentration of sulfuric acid is 0.07 mol / L.

[0047] Preparation Example 8

[0048] An anodic oxidation liquid, which is different from Preparation Example 3 in that: the concentration of hyperbranched polyester is 3 g / L; the concentration of sodium tannate is 0.0317 mol / L; and the concentration of sulfuric acid is 0.075 mol / L.

[0049] Preparation Example 9

[0050] A sealing liquid, comprising methyl silicate, siloxane, propylene glycol, a surfactant, triethanolamine and water. The concentration of methyl silicate is 12 g / L; the siloxane is 3-aminopropyl triethoxysilane, the concentration of which is 4.6 g / L; the concentration of propylene glycol is 3.2 g / L; the surfactant is polyoxyethylene lauryl ether, the concentration of which is 0.8 g / L; and the concentration of triethanolamine is 2.3 g / L.

[0051] Preparation Example 10

[0052] A sealing liquid, comprising methyl silicate, siloxane, propylene glycol, a surfactant, triethanolamine and water. The concentration of methyl silicate is 12 g / L; the concentration of siloxane is methyl triethoxysilane is 4.6 g / L; the concentration of propylene glycol is 3.2 g / L; the surfactant is polyoxyethylene lauryl ether is 0.8 g / L; the concentration of triethanolamine is 2.3 g / L.

[0053] Preparation Example 11

[0054] A sealing liquid, comprising methyl silicate, siloxane, propylene glycol, a surfactant, triethanolamine and water. The concentration of methyl silicate is 12 g / L; the concentration of siloxane is 3-aminopropyltriethoxysilane is 4.6 g / L; the concentration of propylene glycol is 3.2 g / L; the surfactant is sodium dodecylbenzene sulfonate is 0.8 g / L; the concentration of triethanolamine is 2.3 g / L.

[0055] Preparation Example 12

[0056] A sealing liquid, comprising methyl silicate, siloxane, propylene glycol, a surfactant and water. The concentration of methyl silicate is 12 g / L; the concentration of siloxane is 3-aminopropyl triethoxysilane is 4.6 g / L; the concentration of propylene glycol is 3.2 g / L; and the surfactant is polyoxyethylene lauryl ether is 0.8 g / L.

[0057] Preparation Example 13

[0058] A sealing liquid, comprising methyl silicate, siloxane, propylene glycol, a surfactant and water. The concentration of methyl silicate is 6 g / L; the siloxane is 3-aminopropyl triethoxysilane, the concentration of which is 2.3 g / L; the concentration of propylene glycol is 1.6 g / L; the surfactant is polyoxyethylene lauryl ether, the concentration of which is 0.4 g / L; and the concentration of triethanolamine is 0.6 g / L.

[0059] Preparation Example 14

[0060] A sealing liquid, comprising methyl silicate, siloxane, propylene glycol, a surfactant and water. The concentration of methyl silicate is 9.6 g / L; the siloxane is 3-aminopropyl triethoxysilane, the concentration of which is 3.68 g / L; the concentration of propylene glycol is 2.56 g / L; the surfactant is polyoxyethylene lauryl ether, the concentration of which is 0.64 g / L; and the concentration of triethanolamine is 0.96 g / L.

[0061] Preparation Example 15

[0062] A sealing liquid, comprising methyl silicate, siloxane, propylene glycol, a surfactant and water. The concentration of methyl silicate is 14.4 g / L; the siloxane is 3-aminopropyl triethoxysilane, the concentration of which is 5.52 g / L; the concentration of propylene glycol is 3.84 g / L; the surfactant is polyoxyethylene lauryl ether, the concentration of which is 0.96 g / L; and the concentration of triethanolamine is 1.44 g / L.

[0063] Preparation Example 16

[0064] A sealing liquid, comprising methyl silicate, siloxane, propylene glycol, a surfactant and water. The concentration of methyl silicate is 18 g / L; the siloxane is 3-aminopropyl triethoxysilane, the concentration of which is 6.9 g / L; the concentration of propylene glycol is 4.8 g / L; the surfactant is polyoxyethylene lauryl ether, the concentration of which is 1.21 g / L; and the concentration of triethanolamine is 1.8 g / L.

[0065] Comparative Preparation Example 1

[0066] The invention discloses an anodic oxidation liquid, which comprises sulfuric acid and water, and the concentration of the sulfuric acid is 0.06 mol / L.

[0067] Comparative Preparation Example 2

[0068] An anodic oxidation liquid comprises sodium tannate, sulfuric acid and water, wherein the concentration of the sodium tannate is 0.005 mol / L and the concentration of the sulfuric acid is 0.06 mol / L.

[0069] Comparative Preparation Example 3

[0070] An anodic oxidation liquid comprises hyperbranched polyester, sulfuric acid and water. The hyperbranched polyester is prepared in Example 1, the concentration of the hyperbranched polyester is 2.4 g / L, and the concentration of the sulfuric acid is 0.06 mol / L.

[0071] Example 1

[0072] A method for preparing an anti-corrosion film layer on the surface of an electrical material aluminum alloy comprises the following steps:

[0073] Immerse the aluminum alloy in 55°C water, remove grease and dirt on the workpiece surface under the action of ultrasound, and then rinse the surface with clean water;

[0074] The cleaned aluminum alloy is immersed in a NaOH solution with a concentration of 40 g / L for 15 seconds to remove the oxide layer on the surface of the aluminum alloy, and then the surface of the workpiece is rinsed with clean water to remove the residual alkali solution to obtain the alkali-treated aluminum alloy;

[0075] The alkali-treated aluminum alloy is immersed in a 7.2wt% nitric acid solution for 29s to remove surface deposits of the alkali-treated aluminum alloy, and then the ash on the surface of the workpiece is removed by washing with clean water to obtain an aluminum alloy to be treated;

[0076] The aluminum alloy to be treated is immersed in an anodizing solution at 12°C and powered on for anodizing. The current during anodizing is 1.5A / dm 2 , the anodizing time is 35 min, and anodized aluminum alloy is obtained.

[0077] The anodized aluminum alloy is placed in a pre-prepared sealing liquid to perform a sealing treatment on the film surface of the oxide film at 80±2°C. The sealing treatment immersion time is 35 minutes. After the sealing is completed, a sealed aluminum alloy is obtained.

[0078] The workpiece surface is rinsed with pure water to remove the residual sealing liquid, and then dried to obtain an electrical material aluminum alloy with an anti-corrosion film layer on the surface.

[0079] The anodizing solution used for anodizing was prepared in Preparation Example 3.

[0080] The sealing liquid used for the sealing treatment is prepared in Preparation Example 9.

[0081] Embodiment 2~6

[0082] A method for preparing an anti-corrosion film layer on the surface of an electrical material aluminum alloy is different from Example 1 in that the anodizing liquid used for anodizing has a different source, as shown in Table 1 below.

[0083] Table 1. Sources of anodizing solutions for Examples 2 to 6

[0084]

[0085] Embodiments 7 to 13

[0086] A method for preparing an anti-corrosion film layer on the surface of an electrical material aluminum alloy, which differs from Example 1 in that the sealing liquid used for anodizing has a different source, as shown in Table 2 below.

[0087] Table 2. Sources of sealing liquids for Examples 7 to 13

[0088]

[0089] Embodiment 14

[0090] A method for preparing an anti-corrosion film layer on the surface of an electrical material aluminum alloy, which is different from Example 1 in that the process parameters during anodizing are: the current during anodizing is 1.0A / dm 2 , the anodizing liquid temperature is 12°C, and the anodizing time is 52.5min.

[0091] Embodiment 15

[0092] A method for preparing an anti-corrosion film layer on the surface of an electrical material aluminum alloy, which differs from Example 1 in that the process parameters during anodizing are: the current during anodizing is 1.25A / dm 2 , the anodizing liquid temperature is 12°C, and the anodizing time is 42 minutes.

[0093] Example 16

[0094] A method for preparing an anti-corrosion film layer on the surface of an electrical material aluminum alloy, which differs from Example 1 in that the process parameters during anodizing are: the current during anodizing is 1.7A / dm 2 , the anodizing liquid temperature is 12℃, and the anodizing time is 30min.

[0095] Embodiment 17

[0096] A method for preparing an anti-corrosion film layer on the surface of an electrical material aluminum alloy, which is different from Example 1 in that the process parameters during anodizing are: the current during anodizing is 3A / dm 2 , the anodizing liquid temperature is 12°C, and the anodizing time is 17.5min.

[0097] Embodiment 18

[0098] A method for preparing an anti-corrosion film layer on the surface of an electrical material aluminum alloy, which differs from Example 1 in that the sealing liquid temperature during the sealing treatment is 80±2°C and the sealing treatment time is 20 minutes.

[0099] Embodiment 19

[0100] A method for preparing an anti-corrosion film layer on the surface of an electrical material aluminum alloy, which differs from Example 1 in that the sealing liquid temperature during the sealing treatment is 80±2°C and the sealing treatment time is 30 minutes.

[0101] Embodiment 20

[0102] A method for preparing an anti-corrosion film layer on the surface of an electrical material aluminum alloy, which differs from Example 1 in that the sealing liquid temperature during the sealing treatment is 80±2°C and the sealing treatment time is 38 minutes.

[0103] Embodiment 21

[0104] A method for preparing an anti-corrosion film layer on the surface of an electrical material aluminum alloy, which differs from Example 1 in that the sealing liquid temperature during the sealing treatment is 80±2°C and the sealing treatment time is 45 minutes.

[0105] Comparative Example 1

[0106] A method for preparing an anti-corrosion film layer on the surface of an electrical material aluminum alloy, which differs from Example 1 in that the anodizing liquid used for anodizing is prepared by Comparative Preparation Example 1.

[0107] Comparative Example 2

[0108] A method for preparing an anti-corrosion film layer on the surface of an electrical material aluminum alloy, which differs from Example 1 in that the anodizing liquid used for anodizing is prepared by Comparative Preparation Example 2.

[0109] Comparative Example 3

[0110] A method for preparing an anti-corrosion film layer on the surface of an electrical material aluminum alloy, which differs from Example 1 in that the anodizing liquid used for anodizing is prepared by Comparative Preparation Example 3.

[0111] The electrical material aluminum alloys obtained in Examples 1 to 21 and Comparative Examples 1 to 3 were tested, including the adhesion test of the surface anti-corrosion film layer and the salt spray corrosion resistance test of the surface anti-corrosion film layer.

[0112] Adhesion test of surface anti-corrosion film: According to the cross-cutting test in 2.8 of GB / T 5270-2005 Review of test methods for adhesion strength of electrodeposited and chemically deposited metal coatings on metal bodies, 5×5 square grids with a side length of 1mm are cut, and the adhesion is graded based on the cross-cutting test results according to the standard GB / T 9286. The results are expressed in four adhesion grades from 0 to 4.

[0113] Level 0 means that the cutting edge is completely smooth and no grid has fallen off; Level 1 means that a small amount of film has fallen off at the intersection of the scratches, but the falling area is less than 5%; Level 2 means that a small amount of film has fallen off at the intersection of the scratches or along the scratches, and the falling area is greater than 5% and less than 10%; Level 3 means that the coating has fallen off along the cutting edge or all in large pieces, and / or has partially or completely fallen off at different parts of the grid, and the affected cross-cut area is significantly greater than 15, but not significantly greater than 35%; Level 4 means that the degree of peeling is greater than Level 3.

[0114] Salt spray corrosion resistance test of surface anti-corrosion film layer: select a 80mm×100mm surface as the test surface, and test it according to the neutral salt spray test method in "GB / T 10125-2021 Artificial atmosphere corrosion test salt spray test". The test temperature is 35℃, the corrosive medium is 5wt% sodium chloride solution, the pH value of the corrosive medium is set to 7, the spray pressure of the spray box is 80kPa, the test surface is at an angle of 20° to the vertical direction, and the test area is 80cm 2 The salt spray deposition rate is 1.8ml / h; the test results are measured by the time when pitting corrosion appears on the test surface. The later the pitting corrosion appears, the better the corrosion resistance of the surface anti-corrosion film layer.

[0115] The test results are shown in the table below.

[0116] Table 3. Test results of Examples 1 to 21 and Comparative Examples 1 to 3

[0117]

[0118] Combined with Table 1, comparing Example 1 with Comparative Examples 1 to 3, the anodizing solution of Example 1 simultaneously added hyperbranched polyester and sodium tannate, the anodizing solution of Comparative Example 1 was only a sulfuric acid solution, the anodizing solution of Comparative Example 2 was sodium tannate, sulfuric acid, and water, and the anodizing solution of Comparative Example 3 was a hyperbranched polyester, sulfuric acid, and water;

[0119] The adhesion level of Example 1 is better than that of Comparative Examples 2-3, and the adhesion level of Comparative Examples 2-3 is better than that of Example 1;

[0120] The corrosion resistance of Example 1 is significantly better than that of Comparative Examples 2-3, and the improvement of the corrosion resistance of Example 1 over that of Comparative Examples 2-3 is also significantly greater than the improvement of Comparative Examples 2-3 over that of Comparative Example 1.

[0121] The reason for this is that sodium tannate and hyperbranched polyester are added to the anodizing liquid. Sodium tannate combines with non-aluminum metal ions dissolved from aluminum alloy in an acidic environment to prevent the non-aluminum metal ion hydroxide from combining and depositing into the anodized film. Sodium tannate can also repair tiny defects on the metal surface and promote the production of oxide film, while increasing the growth rate and density of the anodized film on the surface of aluminum alloy. Hyperbranched polyester can improve the deposition pattern of aluminum oxide and aluminum hydroxide complexes in the anodized film and increase the corrosion resistance of the anodized film. In addition, hyperbranched polyester can also reduce the reaction activation energy, assist sodium tannate in combining with non-aluminum metal ions, and enhance the effect of sodium tannate. Therefore, it can significantly improve the adhesion and corrosion resistance of the anti-corrosion film layer on the surface of electrical material aluminum alloy.

[0122] Comparing Example 1 and Example 2, the hyperbranched polyester in the anodizing liquid used in Example 1 is an acrylic acid-terminated modified hyperbranched polyester, and the corrosion resistance of Example 1 is significantly better than that of Example 2. The reason is that the hyperbranched ester has a greater destructive effect on the hydrated ion layer around the metal ions, and has a better effect on improving the deposition mode of the aluminum oxide and aluminum hydroxide complex of the anodized film, and the anodized film has better corrosion resistance.

[0123] By comparing Example 1 with Examples 3 to 6, it can be seen that the adhesion grades of Example 1, Example 5 and Example 4 in the test results are better than those of Example 3 and Example 6, and the corrosion resistance is from high to low as follows: Example 1, Example 5, Example 4, Example 6, and Example 3. Considering the adhesion and corrosion resistance, when the concentration of hyperbranched polyester in the anodizing liquid in the present application is 2 to 2.8 g / L, the concentration of sodium tannate is 0.021 to 0.029 mol / L, and the concentration of sulfuric acid is 0.05 to 0.07 mol / L, the adhesion and corrosion resistance of the anti-corrosion film layer on the surface of the electrical material aluminum alloy are better.

[0124] Comparing Example 1 and Example 7, the corrosion resistance of Example 1 is better than that of Example 7. This is because the siloxane in the sealing liquid of Example 1 is 3-aminopropyltriethoxysilane, and 3-aminopropyltriethoxysilane helps to significantly reduce the surface roughness of the coating and improve the hydrophobicity of the coating, effectively slowing down the penetration of corrosive media, and the obtained electrical material aluminum alloy surface anti-corrosion film layer has good anti-corrosion performance.

[0125] Comparing Example 1 and Example 8, the corrosion resistance of Example 1 is better than that of Example 8, and the adhesion grade of Example 1 is better than that of Example 8. Therefore, the effect of polyoxyethylene lauryl ether in the sealing liquid is still better at above 70°C, and it has a better dispersing effect on methyl silicate and siloxane in the sealing liquid. The obtained electrical material aluminum alloy surface anticorrosive film layer has good adhesion and anticorrosion performance.

[0126] Comparing Example 1 and Example 9, the corrosion resistance of Example 1 is better than that of Example 8, and the adhesion level of Example 1 is better than that of Example 8. The reason is that triethanolamine can form a complex with the residual aluminum ions in the pores of the anodized film, eliminate the residual aluminum ions and fill the pores of the oxide film, thereby improving the corrosion resistance of the oxide film, and the addition of triethanolamine can also reduce the adsorption of the oxide film surface, thereby improving its corrosion resistance to corrosive media.

[0127] Combining Example 1 and Examples 14 to 17, the total amount of current applied to Example 1 and Examples 14 to 17 is the same, and the difference lies in the adjustment of the current applied and the anodizing treatment time. In the test results, the adhesion levels of Example 1 and Example 15 are better than those of Examples 14, 16, and 17, the corrosion resistance of Example 1 is better than that of Example 15, and the corrosion resistance of Example 15 is better than that of Examples 14, 16, and 17. Therefore, the current during anodizing is 1.5 to 1.25 A / dm 2 , the anodizing liquid temperature is 12°C, and the anodizing time is 35~42min.

[0128] In combination with Example 1 and Examples 18 to 21, the adhesion levels of Example 1 and Examples 19 to 21 are better than those of Example 18, and the corrosion resistance is ranked from high to low as Example 21, Example 20, Example 1, Example 19, and Example 18. At the same time, the improvement of Example 21 and Example 20 over Example 1 has reached marginal benefits. Therefore, the sealing liquid temperature in this application is 80±2°C, and the sealing treatment time is 30 to 38min. The anti-corrosion film layer on the surface of the electrical material aluminum alloy obtained under these process parameters has good anti-corrosion performance and high production efficiency.

[0129] This specific embodiment is only an explanation of the present invention, and it is not a limitation of the present invention. After reading this specification, those skilled in the art can make non-creative modifications to this embodiment as needed, but as long as it is within the scope of protection required by the present invention, it will be protected by the patent law.

Claims

1. A method for preparing an anti-corrosion film layer on the surface of an electrical material aluminum alloy, characterized in that: The following steps are included in sequence: Degreasing, alkaline etching, neutralization and decontamination, anodizing, sealing, water washing and drying; The anodizing liquid used in the anodizing step is a mixed composite liquid, which includes hyperbranched polyester, sodium tannate, and sulfuric acid. The concentration of the hyperbranched polyester is 2-2.8 g / L, the concentration of sodium tannate is 0.021-0.029 mol / L, and the concentration of sulfuric acid is 0.05-0.07 mol / L. The current during the anodizing step is 1.5-1.25 A / dm 2 , the anodizing liquid temperature is 12°C, and the anodizing time is 35~42min.

2. The method for preparing an anti-corrosion film layer on the surface of an electrical material aluminum alloy according to claim 1, characterized in that: The hyperbranched polyester is an acrylic acid-terminated modified hyperbranched polyester.

3. The method for preparing the anticorrosion film layer on the surface of the electrical material aluminum alloy according to claim 1, characterized in that: The sealing liquid components in the sealing step include methyl silicate, siloxane, propylene glycol, and a surfactant, wherein the concentration of methyl silicate is 9.6-14.4 g / L, the concentration of siloxane is 3.69-5.52 g / L, the concentration of propylene glycol is 2.56-3.84 g / L, and the concentration of the surfactant is 0.64-0.96 g / L.

4. The method for preparing the anticorrosion film layer on the surface of the electrical material aluminum alloy according to claim 3, characterized in that: The sealing liquid component in the sealing step also includes triethanolamine.

5. The method for preparing the anticorrosion film layer on the surface of the electrical material aluminum alloy according to claim 3, characterized in that: The surfactant is polyoxyethylene lauryl ether.

6. The method for preparing the anticorrosion film layer on the surface of the electrical material aluminum alloy according to claim 3, characterized in that: The siloxane was 3-aminopropyltriethoxysilane.

7. The method for preparing the anticorrosion film layer on the surface of the electrical material aluminum alloy according to claim 1, characterized in that: The sealing liquid temperature is 80±2℃, and the sealing treatment time is 30~38min.

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