Anodic oxidation solution and anodic oxidation method suitable for aluminum material

Abstract

The invention provides an anodic oxidation solution. The anodic oxidation solution comprises the following components of 5 g / L to 20 g / L of citric acid, 20 g / L to 50 g / L of oxalic acid, 4 g / L to 7 g / L of inorganic cerium salt, 5 g / L to 9 g / L of triethanolamine, 1 g / L to 3 g / L of aluminum isopropoxide and 5 g / L to 7 g / L of 3-methyl-2-pentene-4-alkyne-1-alcohol. The invention further provides an anodic oxidation method suitable for the aluminum material, according to the anodic oxidation method, the anodic oxidation liquid is adopted for oxidation, the oxidation temperature is 8-12 DEG C, the oxidation current density is 1-5 A / dm < 2 >, the oxidation voltage is 30-50 V, and the oxidation time is 20-30 min. The anodic oxidation liquid is matched with oxidation parameters, so that the film forming speed of an oxidation film is increased, and the voltage resistance of a product is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum surface treatment technology, and in particular to an anodizing liquid and an anodizing method suitable for aluminum. Background Art

[0002] Aluminum is often anodized to improve its performance. Currently, acids such as sulfuric acid and oxalic acid are used as anodizing baths. However, sulfuric acid anodizing suffers from poor voltage resistance. Furthermore, sulfuric acid is a strong acid, and the oxide film undergoes a process of film formation and dissolution during anodizing. Strong acids easily dissolve the oxide film, slowing the formation of the desired film thickness. Oxalic acid, when used as an anodizing bath, also suffers from slow film formation. Current acid agents and oxidation processes cannot achieve both the advantages of voltage resistance and rapid film formation. Summary of the Invention

[0003] In order to overcome the deficiencies of the prior art, the present invention aims to provide an anodizing solution that is helpful in assisting in increasing the film forming speed and the voltage resistance of anodized aluminum.

[0004] In addition, the present application also provides an anodizing method suitable for aluminum materials, and the anodized aluminum materials obtained by this method have a faster film forming speed and higher voltage resistance.

[0005] In order to solve the above problems, the technical solutions adopted by the present invention are as follows: An anodic oxidation liquid comprises the following components: 5-20 g / L of citric acid, 20-50 g / L of oxalic acid, 4-7 g / L of inorganic cerium salt, 5-9 g / L of triethanolamine, 1-3 g / L of triisopropoxyaluminum, and 5-7 g / L of 3-methyl-2-pentene-4-yn-1-ol.

[0006] In some possible embodiments, the inorganic cerium salt is selected from at least one of cerium citrate and cerium nitrate.

[0007] In some possible embodiments, the concentration of the citric acid is 10-15 g / L, the concentration of the oxalic acid is 25-45 g / L, the concentration of the inorganic cerium salt is 5-7 g / L, the concentration of the triethanolamine is 7-9 g / L, and the concentration of the 3-methyl-2-pentene-4-yn-1-ol is 5.5-6 g / L.

[0008] The present application also provides an anodizing method applicable to aluminum materials, comprising the following steps: After masking the non-anodized area of ​​the aluminum material, the aluminum material is mounted on a conductive jig; The aluminum material mounted on the conductive fixture is placed in a degreasing tank and degreased using an alkaline degreasing solution; The degreased aluminum material is sent to a first water washing tank to remove residual alkaline degreasing liquid; The aluminum material after water washing is sent into an alkaline washing tank for etching to remove the oxide film and the tip; sending the etched aluminum material into a second water washing tank to remove residual alkaline washing solution; The etched and washed aluminum material is sent to a deashing tank for deashing to remove reactants produced by the alkaline washing reaction; sending the aluminum material after deashing into a third water washing tank to remove residual deashing liquid; The aluminum material after ash removal and water washing is sent to the anodizing tank for oxidation. The anodizing tank is filled with the anodizing solution. The temperature of the anodizing solution in the anodizing tank is 8-12°C, and the oxidation current density is 1-5A / dm 2 , voltage is 30-50V, and oxidation time is 20-30min.

[0009] In some possible implementations, the following further comprises: Between the oxidation and removal of residual de-ashing liquid steps, the aluminum is subjected to overall high-pressure washing using a high-pressure water gun; After the oxidized aluminum material is removed from the anodizing tank, a high-pressure water gun is used to perform high-pressure water flushing on the entire aluminum material; Soak the washed aluminum material in a pure water tank at room temperature for 5-10 minutes; Use filtered, oil-free and water-free compressed air to blow dry the surface of the soaked aluminum material, and then remove the conductive fixture.

[0010] In some possible implementations, the concentration of the degreasing agent in the alkaline degreasing solution is 30-40 g / L.

[0011] In some possible implementations, the components of the alkaline cleaning agent in the alkaline cleaning tank are 25-55 g / L of sodium hydroxide and 5-25 g / L of sodium gluconate.

[0012] In some possible implementations, the bath temperature of the alkali washing tank is 40-50° C., and the aluminum material is immersed in the alkali washing tank for 6-12 minutes.

[0013] In some possible implementations, the deashing liquid in the deashing tank contains 25-40 g / L of nitric acid and 25-45 g / L of citric acid.

[0014] In some possible implementations, the temperature of the tank liquid in the ash removal tank is room temperature, and the aluminum material is immersed in the ash removal tank for 3-5 minutes.

[0015] Compared with the prior art, the present invention has the following beneficial effects: In the present application, by the synergistic coordination between specific concentrations of citric acid, oxalic acid, inorganic cerium salt, triethanolamine, triisopropoxy aluminum, 3-methyl-2-pentene-4-alkyne-1-ol and anodizing parameters, it is beneficial to improve the film forming speed of the anodized film and to improve the voltage resistance of the aluminum material. The synergistic effect of triethanolamine and triisopropoxy aluminum is also beneficial to avoid the rapid dissolution of the formed oxide film, and the complexation of triethanolamine, 3-methyl-2-pentene-4-alkyne-1-ol and aluminum is also beneficial to delaying the formation speed of the barrier layer in the initial stage of anodizing, thereby facilitating the rapid thickening of the oxide film. The synergistic effect between the components of the anodizing solution is also beneficial to anodizing at a lower temperature, thereby facilitating slowing down the dissolution of the oxide film.

[0016] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a flow chart of an anodizing method for aluminum provided in one embodiment of the present application. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0020] The following embodiments of the present invention are described in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0021] An embodiment of the present application provides an anodizing liquid comprising the following ingredients: 5-20 g / L of citric acid, 20-50 g / L of oxalic acid, 4-7 g / L of an inorganic cerium salt, 5-9 g / L of triethanolamine, 1-3 g / L of triisopropoxyaluminum, and 5-7 g / L of 3-methyl-2-pentene-4-yn-1-ol.

[0022] Preferably, the concentration of citric acid is 10-15 g / L, the concentration of oxalic acid is 25-45 g / L, the concentration of the inorganic cerium salt is 5-7 g / L, the concentration of triethanolamine is 7-9 g / L, and the concentration of 3-methyl-2-pentene-4-yn-1-ol is 5.5-6 g / L. This preferred concentration range is conducive to further improving voltage resistance and increasing film formation speed.

[0023] In some embodiments, the inorganic cerium salt is selected from at least one of cerium citrate or cerium nitrate.

[0024] Another embodiment of the present application provides an anodizing method for aluminum materials, comprising the following steps: Step S101: After masking the non-anodized areas of the aluminum material, the aluminum material is mounted on a conductive fixture. For example, acid- and alkali-resistant rubber plugs can be used to mask the screw holes of the aluminum material that are not used for hoisting, and acid- and alkali-resistant tape and acid- and alkali-resistant resin can be used to mask the non-anodized surface of the board.

[0025] In step S102 , the aluminum material mounted on the conductive fixture is placed in a degreasing tank and degreased using an alkaline degreasing solution.

[0026] In some embodiments, the degreasing agent in the alkaline degreasing solution has a concentration of 30-40 g / L. Exemplarily, the degreasing agent may include sodium hydroxide, sodium carbonate, sodium silicate, or sodium phosphate. The alkaline degreasing solution may be an aqueous solution. Selecting the above concentration of the degreasing agent facilitates effective removal of grease from the aluminum surface.

[0027] In step S103 , the degreased aluminum material is sent to a first water washing tank to remove residual alkaline degreasing liquid.

[0028] In step S104 , the washed aluminum material is sent to an alkaline washing tank for etching to remove the oxide film and the tip.

[0029] In some embodiments, the alkaline cleaning agent in the alkaline cleaning tank comprises 25-55 g / L sodium hydroxide and 5-25 g / L sodium gluconate. A specific concentration of the alkaline cleaning agent is beneficial for improving the efficiency of removing the oxide film and the tip.

[0030] In some embodiments, the temperature of the alkali cleaning tank is 40-50° C., and the aluminum material is immersed in the alkali cleaning tank for 6-12 minutes. The alkali cleaning temperature combined with a specific alkali cleaning agent is conducive to effectively removing the oxide film and the tip in a relatively short time.

[0031] In step S105 , the etched aluminum material is sent to a second water washing tank to remove residual alkaline washing solution.

[0032] In step S106 , the etched and washed aluminum material is sent to a deashing tank for deashing to remove reactants generated by the alkaline washing reaction.

[0033] In some embodiments, the deashing liquid in the deashing tank contains 25-40 g / L of nitric acid and 25-45 g / L of citric acid. The composition of the deashing liquid facilitates the rapid removal of reactants generated by the alkaline washing reaction.

[0034] In some embodiments, the temperature of the bath liquid in the deashing tank is room temperature, and the aluminum material is immersed in the deashing tank for 3-5 minutes. The selection of the deashing liquid is conducive to shortening the removal time, thereby improving the processing efficiency.

[0035] In step S107 , the aluminum material after ash removal is sent to a third water washing tank to remove residual ash removal liquid.

[0036] Step S108: The aluminum material after ash removal and water washing is sent to an anodizing tank for oxidation. The anodizing tank is filled with the anodizing solution described in the above embodiment. The temperature of the anodizing solution in the anodizing tank is 8-12°C, and the oxidation current density is 1-5A / dm 2 , voltage is 30-50V, and oxidation time is 20-30min.

[0037] In some embodiments, between step S107 and step S108, a step is further included: using a high-pressure water gun to perform high-pressure washing on the entire aluminum material to remove residual chemical solution and impurities on the surface of the aluminum material, thereby improving the anodizing effect. In some embodiments, the high-pressure water gun also strengthens the conductive connection of the aluminum material after high-pressure washing to prevent poor conductivity during the anodizing process.

[0038] In step S109, after the oxidized aluminum material is removed from the anodizing tank, a high-pressure water gun is used to perform high-pressure water flushing on the entire aluminum material to remove residual chemical solution on the surface.

[0039] Step S1010: Place the washed aluminum material into a pure water tank at room temperature and soak for 5-10 minutes.

[0040] In step S1011 , filtered, oil-free and water-free compressed air is used to blow dry the surface of the aluminum material after soaking, and then the conductive fixture is removed.

[0041] In the present application, by the synergistic coordination between specific concentrations of citric acid, oxalic acid, inorganic cerium salt, triethanolamine, triisopropoxy aluminum, 3-methyl-2-pentene-4-alkyne-1-ol and anodizing parameters, it is beneficial to improve the film formation speed of the anodized film and to improve the voltage resistance of the anodized aluminum. The synergistic effect of triethanolamine and triisopropoxy aluminum is also beneficial to avoid the rapid dissolution of the formed oxide film, and the complexation of triethanolamine, 3-methyl-2-pentene-4-alkyne-1-ol and aluminum is also beneficial to delaying the formation speed of the barrier layer in the initial stage of anodizing, thereby facilitating the rapid thickening of the oxide film. The synergistic effect between the components of the anodizing solution is also beneficial to anodizing at a lower temperature, thereby helping to slow down the dissolution of the oxide film.

[0042] Example 1 After masking the non-anodized areas of the aluminum, the aluminum is mounted on a conductive fixture. Screw holes not used for hoisting can be masked with acid- and alkali-resistant rubber plugs. Non-anodized surfaces can be masked with acid- and alkali-resistant tape and resin. The aluminum, mounted on the conductive fixture, is degreased in a degreasing tank using an alkaline degreasing solution. The degreasing agent in the alkaline degreasing solution (aqueous solution) contains sodium hydroxide at a concentration of 30 g / L. After degreasing, the aluminum is rinsed in a first water washing tank to remove any residual alkaline degreasing solution. After washing, the aluminum is etched in an alkaline washing tank to remove the oxide film and sharp edges. The alkaline washing agent in the alkaline washing tank consists of 55 g / L sodium hydroxide and 5 g / L sodium gluconate. The bath temperature is 45°C, and the aluminum is immersed in the alkaline washing tank for 8 minutes. After etching, the aluminum is rinsed in a second water washing tank to remove any residual alkaline washing solution. The etched and washed aluminum material is sent to a deashing tank for deashing to remove the reactants produced by the alkaline washing reaction. The deashing liquid in the deashing tank contains 25g / L nitric acid and 40g / L citric acid. The tank liquid temperature of the deashing tank is room temperature, and the aluminum material is immersed in the deashing tank for 3 minutes. The deashed aluminum material is sent to a third water washing tank to remove the residual deashing liquid. A high-pressure water gun is used to perform high-pressure washing on the aluminum material as a whole to remove the residual liquid and impurities on the surface of the aluminum material. The deashed aluminum material is sent to a third water washing tank to remove the residual deashing liquid. The aluminum material after ash removal and water washing is placed in an anodizing tank for oxidation. The anodizing tank contains an anodizing solution, which includes the following ingredients: 5g / L citric acid, 24g / L oxalic acid, 4g / L cerium citrate, 6g / L triethanolamine, 1g / L triisopropoxyaluminum, and 7g / L 3-methyl-2-pentene-4-yn-1-ol. The bath temperature in the anodizing tank is 12°C, and the oxidation current density is 2A / dm 2, the voltage is 30V, and the oxidation time is 28min. After the oxidized aluminum material is removed from the anodizing tank, a high-pressure water gun is used to perform high-pressure water flushing on the aluminum material as a whole to remove the residual liquid on the surface. The rinsed aluminum material is sent to a pure water tank at room temperature and soaked for 8 minutes. Use filtered, oil-free and water-free compressed air to blow dry the surface of the soaked aluminum material, and then remove the conductive fixture. The thickness of the obtained oxide film is 10μm. The withstand voltage value of the product obtained after anodizing is 0.40kV.

[0043] Example 2 The difference from Example 1 is that the concentration of the degreasing agent in the alkaline degreasing liquid (aqueous solution) is 35g / L, the degreasing agent is sodium carbonate, and the composition of the alkaline cleaning agent in the alkaline washing tank is 25g / L sodium hydroxide and 10g / L sodium gluconate. The bath temperature of the alkaline washing tank is 40°C. The time for the aluminum material to be immersed in the alkaline washing tank is 6 minutes. The composition of the deashing liquid in the deashing tank is 30g / L nitric acid and 25g / L citric acid. The time for the aluminum material to be immersed in the deashing tank is 4 minutes. The anodizing liquid includes the following components: 8g / L citric acid, 20g / L oxalic acid, 4.5g / L cerium nitrate, 5g / L triethanolamine and 3g / L triisopropoxyaluminum, 5g / L 3-methyl-2-pentene-4-yn-1-ol. The bath temperature in the anodizing tank is 8°C, and the oxidation current density is 5A / dm 2 The aluminum material was rinsed and placed in a pure water tank at room temperature for 5 minutes. The resulting oxide film had a thickness of 10 μm. The withstand voltage of the anodized product was 0.5 kV.

[0044] Example 3 The difference from Example 1 is that the concentration of the degreasing agent in the alkaline degreasing liquid (aqueous solution) is 40g / L, the degreasing agent is sodium silicate, and the composition of the alkaline cleaning agent in the alkaline washing tank is 30g / L sodium hydroxide and 25g / L sodium gluconate. The bath temperature of the alkaline washing tank is 50°C. The time for the aluminum material to be immersed in the alkaline washing tank is 12 minutes. The composition of the deashing liquid in the deashing tank is 40g / L nitric acid and 45g / L citric acid. The time for the aluminum material to be immersed in the deashing tank is 3 minutes. The anodizing liquid includes the following components: 10g / L citric acid, 25g / L oxalic acid, 7g / L cerium citrate, 9g / L triethanolamine and 1g / L triisopropoxyaluminum, 6g / L 3-methyl-2-pentene-4-yn-1-ol. The bath temperature in the anodizing tank is 10°C, and the oxidation current density is 4A / dm 2The aluminum material was rinsed and placed in a pure water tank at room temperature for 10 minutes. The resulting oxide film had a thickness of 10 μm. The anodized product had a withstand voltage of 0.64 kV.

[0045] Example 4 The difference from Example 3 is that the degreasing agent is sodium phosphate, the deashing liquid in the deashing tank is composed of the following ingredients: 15g / L citric acid, 45g / L oxalic acid, 5g / L cerium citrate, 7g / L triethanolamine and 2g / L triisopropoxyaluminum, 5.5g / L 3-methyl-2-pentene-4-yn-1-ol. The bath temperature in the anodizing tank is 8°C, and the oxidation current density is 5A / dm 2 The aluminum material was rinsed and placed in a pure water tank at room temperature for 5 minutes. The resulting oxide film had a thickness of 10 μm. The withstand voltage of the anodized product was 0.62 kV.

[0046] Example 5 The difference from Example 3 is that the degreasing agent is sodium phosphate, the deashing liquid in the deashing tank is composed of the following ingredients: 16g / L citric acid, 46g / L oxalic acid, 4.8g / L cerium citrate, 6.8g / L triethanolamine and 2.5g / L triisopropoxyaluminum, 6.5g / L 3-methyl-2-pentene-4-yn-1-ol. The bath temperature in the anodizing tank is 9°C, and the oxidation current density is 3A / dm 2 The aluminum material was rinsed and placed in a pure water tank at room temperature for 8 minutes. The resulting oxide film had a thickness of 10 μm. The anodized product had a withstand voltage of 0.43 kV.

[0047] Comparative Example 1 The difference from Example 1 is that the anodizing solution comprises the following ingredients: 5 g / L citric acid, 24 g / L oxalic acid, 6 g / L triethanolamine, 1 g / L triisopropoxyaluminum, and 7 g / L 3-methyl-2-penten-4-yn-1-ol. The oxidation time is 60 minutes. The bath temperature in the anodizing tank is 20°C. The resulting oxide film has a thickness of 10 μm. The withstand voltage of the product obtained after anodization is 0.2 kV.

[0048] Comparative Example 2 The difference from Example 1 is that the anodizing solution comprises the following ingredients: 5 g / L citric acid, 24 g / L oxalic acid, 4 g / L cerium citrate, 1 g / L triisopropoxyaluminum, and 7 g / L 3-methyl-2-penten-4-yn-1-ol. The oxidation time is 50 minutes. The bath temperature in the anodizing tank is 23°C. The resulting oxide film has a thickness of 10 μm. The product obtained after anodization has a withstand voltage of 0.25 kV.

[0049] Comparative Example 3 The difference from Example 1 is that the anodizing solution comprises the following ingredients: 5 g / L citric acid, 24 g / L oxalic acid, 4 g / L cerium citrate, 6 g / L triethanolamine, and 7 g / L 3-methyl-2-penten-4-yn-1-ol. The resulting oxide film has a thickness of 10 μm. The oxidation time is 55 minutes. The resulting oxide film has a thickness of 10 μm. The product obtained after anodization has a withstand voltage of 0.22 kV.

[0050] Comparative Example 4 The difference from Example 1 is that the anodizing solution comprises the following ingredients: 5 g / L citric acid, 24 g / L oxalic acid, 4 g / L cerium citrate, 6 g / L triethanolamine, and 1 g / L aluminum triisopropoxide. The oxidation time is 45 minutes. The resulting oxide film has a thickness of 10 μm. The product obtained after anodization has a withstand voltage of 0.23 kV.

[0051] Comparative Example 5 The difference from Example 1 is that the anodizing solution contains the following ingredients: 5 g / L citric acid and 24 g / L oxalic acid. The oxidation time is 50 minutes. The resulting oxide film thickness is 10 μm. The withstand voltage of the product after anodization is 0.18 kV.

[0052] Comparative Example 6 The difference from Example 1 is that the bath temperature in the anodizing tank is 13°C and the oxidation current density is 0.5A / dm 2 The voltage was 55V and the oxidation time was 50 minutes. The resulting oxide film had a thickness of 10μm. The withstand voltage of the product after anodization was 0.2kV.

[0053] Comparative Example 7 The difference from Example 1 is that the bath temperature in the anodizing tank is 7°C and the oxidation current density is 5.5A / dm 2 , voltage is 29V, oxidation time is 55min. The withstand voltage value of the product obtained after anodization is 0.22kV.

[0054] This application uses a Krass voltage withstand tester to test the voltage withstand of the product. The test conditions are: the temperature is 20±5℃ and the humidity is 50±10% in a workshop.

[0055] From the comparison of the above embodiments and comparative examples, it can be seen that when an oxide film of the same thickness is produced, the anodizing liquid of the present application, combined with the oxidation parameters, enables the target thickness to be obtained in a shorter time, and the product of the present application has higher voltage resistance.

[0056] The above embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and replacements made by technicians in this field on the basis of the present invention fall within the scope of protection required by the present invention.

Claims

1. An anodic oxidation solution, characterized in that The invention comprises the following ingredients: 5-20 g / L of citric acid, 20-50 g / L of oxalic acid, 4-7 g / L of inorganic cerium salt, 5-9 g / L of triethanolamine, 1-3 g / L of triisopropoxyaluminum, and 5-7 g / L of 3-methyl-2-pentene-4-yn-1-ol.

2. The anodic oxidation solution according to claim 1, wherein The inorganic cerium salt is selected from at least one of cerium citrate and cerium nitrate.

3. The anodic oxidation solution according to claim 1, wherein The concentration of the citric acid is 10-15 g / L, the concentration of the oxalic acid is 25-45 g / L, the concentration of the inorganic cerium salt is 5-7 g / L, the concentration of the triethanolamine is 7-9 g / L, and the concentration of the 3-methyl-2-pentene-4-yn-1-ol is 5.5-6 g / L.

4. A method for anodizing aluminum, characterized in that: The steps include: After masking the non-anodized area of ​​the aluminum material, the aluminum material is mounted on a conductive jig; The aluminum material mounted on the conductive fixture is placed in a degreasing tank and degreased using an alkaline degreasing solution; The degreased aluminum material is sent to a first water washing tank to remove residual alkaline degreasing liquid; The aluminum material after water washing is sent to an alkaline washing tank for etching to remove the oxide film and the tip; sending the etched aluminum material into a second water washing tank to remove residual alkaline washing solution; The etched and washed aluminum material is sent to a deashing tank for deashing to remove reactants produced by the alkaline washing reaction; sending the aluminum material after deashing into a third water washing tank to remove the residual deashing liquid; The aluminum material after ash removal and water washing is sent to an anodizing tank for oxidation. The anodizing tank contains the anodizing solution according to any one of claims 1 to 3. The temperature of the anodizing solution in the anodizing tank is 8-12°C, and the oxidation current density is 1-5A / dm 2 , voltage is 30-50V, and oxidation time is 20-30min.

5. The anodizing method for aluminum materials according to claim 1, wherein: Also includes: Between the oxidation and removal of residual de-ashing liquid steps, the aluminum is subjected to overall high-pressure washing using a high-pressure water gun; After the oxidized aluminum material is removed from the anodizing tank, a high-pressure water gun is used to perform high-pressure water flushing on the entire aluminum material; Soak the washed aluminum material in a pure water tank at room temperature for 5-10 minutes; Use filtered, oil-free and water-free compressed air to blow dry the surface of the soaked aluminum material, and then remove the conductive fixture.

6. The anodizing method for aluminum materials according to claim 4, wherein: The concentration of the degreasing agent in the alkaline degreasing liquid is 30-40 g / L.

7. The anodizing method for aluminum materials according to claim 1, wherein: The components of the alkali cleaning agent in the alkali cleaning tank are 25-55g / L of sodium hydroxide and 5-25g / L of sodium gluconate.

8. The anodizing method for aluminum materials according to claim 7, wherein: The bath temperature of the alkali washing tank is 40-50° C., and the aluminum material is immersed in the alkali washing tank for 6-12 minutes.

9. The anodizing method for aluminum materials according to claim 1, wherein: The deashing liquid in the deashing tank contains 25-40 g / L of nitric acid and 25-45 g / L of citric acid.

10. The anodizing method for aluminum materials according to claim 1, wherein: The temperature of the tank liquid in the ash removal tank is room temperature, and the aluminum material is immersed in the ash removal tank for 3-5 minutes.

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