Aluminum substrate surface anodic oxidation treatment method

Abstract

The invention discloses an aluminum substrate surface anodic oxidation treatment method, which belongs to the technical field of aluminum alloy part oxidation film preparation, and comprises the following steps: cleaning, removing oil stains and impurities on the surface of an aluminum substrate by using an alkaline solution, pickling, soaking the aluminum substrate in an acid solution, removing oxide skin and oxide on the surface, preparing an electrolyte, and carrying out anodic oxidation treatment on the surface of the aluminum substrate. The method comprises the following steps: mixing oxalic acid, sulfuric acid and malonic acid according to a ratio to prepare an electrolyte, putting the aluminum substrate as an anode into the electrolyte, applying current to form an oxidation film on the surface of the aluminum substrate, putting the colored aluminum substrate into a hole sealing solution, sealing micropores of the oxidation film, and improving the corrosion resistance and wear resistance of the aluminum substrate. A hard phase can be formed on the surface of the aluminum alloy through ion implantation, the ions can react with an aluminum element in the aluminum alloy to generate an intermetallic compound, the hardness of the compound is far higher than that of an aluminum alloy matrix, the surface hardness can be remarkably improved, and the wear resistance is also greatly enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy oxide film preparation, and particularly to a method for anodic oxidation treatment on the surface of an aluminum substrate. Background Art

[0002] Anodic oxidation of an aluminum substrate is an electrochemical process. The aluminum substrate is used as the anode and immersed in a specific electrolyte solution, with another conductive material as the cathode. When direct current is applied, an oxidation reaction occurs on the anode surface. The anodic oxidation film can significantly improve the corrosion resistance of the aluminum substrate and increase the overall hardness. By controlling the process parameters of anodic oxidation and subsequent dyeing treatment, the aluminum substrate can obtain different colors and appearance effects. From the existing structure, common oxide films are all oxidized based on aluminum alloy during the production and preparation process. Different oxidation methods result in different hardnesses of the oxide films, but they are all prepared based on aluminum alloy. The difference in the hardness range of the prepared oxide films is always within a certain range, and the hardness strength is not very high. However, due to the wide range of applications of aluminum alloy, the hardness of the oxide film can no longer meet the current use of aluminum alloy. Therefore, we provide a method for anodic oxidation treatment on the surface of an aluminum substrate. Summary of the Invention

[0003] The object of the present invention is to address the above technical problems and provide a method for anodic oxidation treatment on the surface of an aluminum substrate, which solves the drawbacks that in the existing anodic oxidation methods for aluminum alloy parts, the hardness strength of the oxide film is not very high, but due to the wide range of applications of aluminum alloy, the hardness of the oxide film can no longer meet the current use of aluminum alloy.

[0004] To achieve this object, the present invention provides a method for anodic oxidation treatment on the surface of an aluminum substrate, which adopts the following technical embodiments: A method for anodic oxidation treatment on the surface of an aluminum substrate, the method for anodic oxidation treatment on the surface of the aluminum substrate includes the following steps: S1: Cleaning, using an alkaline solution to remove oil stains and impurities on the surface of the aluminum substrate; S2: Pickling, immersing the aluminum substrate in an acidic solution to remove the scale and oxides on the surface; S3: Preparing the electrolyte, mixing oxalic acid, sulfuric acid, and malonic acid in a certain proportion to prepare the electrolyte; S4: Using the aluminum substrate as the anode, putting it into the electrolyte, and applying current to form an oxide film on the surface of the aluminum substrate; S5: Putting the colored aluminum substrate into a sealing solution to seal the micropores of the oxide film and improve its corrosion resistance and wear resistance; S6: Cleaning the aluminum substrate with clean water to remove the residual sealing agent; S7: Uniformly scanning the surface of the oxide film to ensure that the entire surface can receive uniform ion implantation; S8: Select ions for implantation. Generate a high-energy ion beam through an ion implantation device. The implanted ions will collide with the atoms in the oxide film, improving the hardness of the oxide film. S9: Perform a low-temperature annealing treatment to eliminate part of the internal stress generated during the ion implantation process, making the structure of the oxide film more stable.

[0005] Preferably, in the step S1, the alkaline solution is any one of sodium hydroxide solution, sodium carbonate solution, trisodium carbonate solution, and sodium silicate solution.

[0006] Preferably, in the step S2, the acidic solution for pickling is any one of sulfuric acid, hydrochloric acid, and phosphoric acid, and the pickling temperature is 25 - 30 °C, and the pickling time is 30 - 35 minutes.

[0007] Preferably, in the step S3, the concentration of sulfuric acid is 15% - 20%, the concentration of oxalic acid is 2% - 5%, and the concentration of malonic acid is 1% - 3%.

[0008] Preferably, in the step S3, the ratio of sulfuric acid, oxalic acid, and malonic acid is 18:3:2.

[0009] Preferably, in the step S4, the electrolysis time is 20 - 25 minutes, and the electrolysis voltage is 15 - 20 V.

[0010] Preferably, in the step S8, for ion implantation, the implanted energy is 40 - 50 keV, the implantation dose is 1×10¹ 5 -1×10¹ 6 ions / cm², and the pressure for ion implantation is 10⁻ 4 - 10⁻ 6 Pa.

[0011] Preferably, in the step S8, for ion implantation, the selected metal element is any one of Ti, Cr, and Zr.

[0012] Preferably, in the step S9, the annealing temperature is 200 - 250 °C, the annealing time is 2 - 3 hours, the heating rate is controlled at 10 - 50 °C / hour, and the cooling rate can be controlled at 10 - 20 °C / hour.

[0013] Preferably, in the step S9, the annealing atmosphere is any one of nitrogen and argon to prevent the aluminum alloy from oxidizing during the annealing process.

[0014] The present invention has at least the following beneficial effects: In the present invention, the aluminum alloy parts are pretreated by using a combination of a weakly alkaline solution and a strongly alkaline solution to remove the oil stains, impurities and natural oxide film on the surface of the aluminum alloy, making the subsequent oxidation process more stable; In the present invention, the alkaline solution and the pickling solution are respectively used for cleaning and pickling to achieve a comprehensive cleaning of the surface of the aluminum substrate and improve the quality of the oxide film on the aluminum substrate; In the present invention, ion implantation can form hard phases on the surface of the aluminum alloy. These ions will react with the aluminum element in the aluminum alloy to form intermetallic compounds. The hardness of the compounds is much higher than that of the aluminum alloy matrix, which can significantly improve the surface hardness and greatly enhance the wear resistance. During the friction process, the hard phases can resist the cutting and plowing effects of abrasive grains, reduce the wear of the material, and thus extend the service life of the parts. Ion implantation can change the structure and composition of the oxide film on the surface of the aluminum alloy. These ions will form active sites in the oxide film. When the oxide film is eroded by the corrosive medium, rare earth ions can promote the self-repair of the oxide film. The corrosion resistance of the aluminum alloy after ion implantation can be significantly improved.

[0015] In the present invention, during the processing of the aluminum alloy, residual stresses will be generated inside. These residual stresses will cause problems such as deformation and cracking of the aluminum alloy products. Annealing can adjust the organizational structure of the aluminum alloy, refine or homogenize its grains, and thus improve the plasticity of the material. Through the annealing treatment, the grain structure of these aluminum alloys will change, the dislocation density will decrease, and the characteristics of the grain boundaries will be improved. Annealing can also enhance the toughness of the aluminum alloy and reduce the tendency of brittle fracture of the material. When subjected to external force impact, it can absorb more energy without breaking and form a denser composite oxide film.

[0016] Other advantages, objectives and features of the present invention will be partially reflected by the following description and partially understood by those skilled in the art through the research and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a flowchart of Embodiment 1 in a method for anodic oxidation treatment on the surface of an aluminum substrate according to the present invention; Figure 2 It is a flowchart of Embodiment 2 in a method for anodic oxidation treatment on the surface of an aluminum substrate according to the present invention; Figure 3 It is a flowchart of Embodiment 3 in a method for anodic oxidation treatment on the surface of an aluminum substrate according to the present invention; Figure 4 It is a flowchart of Embodiment 4 in a method for anodic oxidation treatment on the surface of an aluminum substrate according to the present invention; Figure 5 It is a comparison chart of the hardness of the oxide films of Embodiments 1-4 in a method for anodic oxidation treatment on the surface of an aluminum substrate according to the present invention. Detailed implementation manners

[0018] In order to make the objectives, technical embodiments and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Embodiment 1

[0019] The method for anodizing the surface of the aluminum substrate in this embodiment is as follows: (1) Cleaning, using an alkaline solution to remove oil stains and impurities on the surface of the aluminum substrate; (2) Pickling, immersing the aluminum substrate in an acidic solution to remove the oxide scale and oxides on the surface; (3) Preparing the electrolyte, mixing oxalic acid, sulfuric acid, and malonic acid in a ratio to prepare the electrolyte. The concentration of sulfuric acid is 15% - 20%, the concentration of oxalic acid is 2% - 5%, and the concentration of malonic acid is 1% - 3%. The ratio of sulfuric acid, oxalic acid, and malonic acid is 18:3:2; (4) Using the aluminum substrate as the anode, putting it into the electrolyte, and forming an oxide film on the surface of the aluminum substrate by applying current. The electrolysis time is 20 - 25 minutes, and the electrolysis voltage is 15 - 20V; (5) Putting the colored aluminum substrate into the sealing solution to seal the micropores of the oxide film and improve its corrosion resistance and wear resistance; (6) Cleaning the aluminum substrate with clean water to remove the remaining sealing agent; (7) Uniformly scanning the surface of the oxide film to ensure that the entire surface can receive uniform ion implantation; (8) Selecting ions for implantation, generating a high-energy ion beam through an ion implantation device. The implanted ions will collide with the atoms in the oxide film to improve the hardness of the oxide film. For ion implantation, the implanted energy is 40 - 50 keV, the implantation dose is 1×10¹ 5 -1×10¹ 6 ions / cm², the pressure of ion implantation is 10⁻ 4 - 10⁻ 6 Pa, and the selected metal element for ion implantation is Ti; (9) Performing low-temperature annealing treatment to eliminate part of the internal stress generated during the ion implantation process and make the structure of the oxide film more stable. The annealing temperature is 200 - 250°C, the annealing time is 2 - 3 hours, the heating rate is controlled at 10 - 50°C / hour, and the cooling rate can be controlled at 10 - 20°C / hour. Embodiment 2

[0020] The method for anodizing the surface of the aluminum substrate in this embodiment is as follows: (1) Cleaning: Use an alkaline solution to remove oil and impurities on the surface of the aluminum substrate. (2) Pickling: Immerse the aluminum substrate in an acidic solution to remove the scale and oxides on the surface. (3) Prepare the electrolyte: Mix oxalic acid, sulfuric acid, and malonic acid in proportion to prepare the electrolyte. The concentration of sulfuric acid is 15% - 20%, the concentration of oxalic acid is 2% - 5%, and the concentration of malonic acid is 1% - 3%. The ratio of sulfuric acid, oxalic acid, and malonic acid is 18:3:2. (4) Use the aluminum substrate as the anode and put it into the electrolyte. By applying current, an oxide film is formed on the surface of the aluminum substrate. The electrolysis time is 20 - 25 minutes, and the electrolysis voltage is 15 - 20V. (5) Put the colored aluminum substrate into the sealing solution to seal the micropores of the oxide film and improve its corrosion resistance and wear resistance. (6) Wash the aluminum substrate with clean water to remove the residual sealing agent. Example 3

[0021] The method for anodic oxidation treatment of the surface of the aluminum substrate in this example is as follows: (1) Cleaning: Use an alkaline solution to remove oil and impurities on the surface of the aluminum substrate. (2) Pickling: Immerse the aluminum substrate in an acidic solution to remove the scale and oxides on the surface. (3) Prepare the electrolyte: Mix oxalic acid, sulfuric acid, and malonic acid in proportion to prepare the electrolyte. The concentration of sulfuric acid is 15% - 20%, the concentration of oxalic acid is 2% - 5%, and the concentration of malonic acid is 1% - 3%. The ratio of sulfuric acid, oxalic acid, and malonic acid is 18:3:2. (4) Use the aluminum substrate as the anode and put it into the electrolyte. By applying current, an oxide film is formed on the surface of the aluminum substrate. The electrolysis time is 20 - 25 minutes, and the electrolysis voltage is 15 - 20V. (5) Put the colored aluminum substrate into the sealing solution to seal the micropores of the oxide film and improve its corrosion resistance and wear resistance. (6) Wash the aluminum substrate with clean water to remove the residual sealing agent; (7) Select ions for implantation. Generate a high-energy ion beam through an ion implantation device. The implanted ions will collide with the atoms in the oxide film to improve the hardness of the oxide film. For ion implantation, the implanted energy is 40 - 50 keV, the implantation dose is 1×10¹ 5 - 1×10¹ 6 ions / cm², and the pressure for ion implantation is 10⁻ 4 - 10⁻ 6 Pa, and the selected metal element for ion implantation is Ti. Example 4

[0022] The method for anodizing the surface of the aluminum substrate in this example is as follows: (1) Cleaning, using an alkaline solution to remove oil and impurities on the surface of the aluminum substrate; (2) Pickling, immersing the aluminum substrate in an acidic solution to remove the scale and oxides on the surface; (3) Preparing the electrolyte, mixing oxalic acid, sulfuric acid, and malonic acid in proportion to prepare the electrolyte. The concentration of sulfuric acid is 15% - 20%, the concentration of oxalic acid is 2% - 5%, and the concentration of malonic acid is 1% - 3%. The ratio of sulfuric acid, oxalic acid, and malonic acid is 18:3:2; (4) Using the aluminum substrate as the anode and placing it in the electrolyte. By applying current, an oxide film is formed on the surface of the aluminum substrate. The electrolysis time is 20 - 25 minutes, and the electrolysis voltage is 15 - 20V; (5) Placing the colored aluminum substrate in the sealing solution to seal the micropores of the oxide film and improve its corrosion resistance and wear resistance; (6) Cleaning the aluminum substrate with clean water to remove the residual sealing agent; (7) Uniformly scanning the surface of the oxide film to ensure that the entire surface can receive uniform ion implantation; (8) Selecting ions for implantation. High-energy ion beams are generated by an ion implantation device. The implanted ions will collide with the atoms in the oxide film to improve the hardness of the oxide film. For ion implantation, the implanted energy is 40 - 50 keV, the implantation dose is 1×10¹ 5 -1×10¹ 6 ions / cm², and the pressure for ion implantation is 10⁻ 4 - 10⁻ 6 Pa. The selected metal element for ion implantation is Ti.

[0023] Comparing with Comparative Examples 1-4, in Example 2, the aluminum substrate is subjected to electrolytic oxidation. Before oxidation, cleaning and pickling are carried out to improve the cleanliness of the overall aluminum substrate and the quality of the subsequent oxide film. The combination of sulfuric acid, oxalic acid and malonic acid is used to improve the density of the oxide film, adjust the growth rate and structure of the oxide film, and to a certain extent improve the hardness and growth rate of the oxide film. In Example 3, on the basis of Example 2, the ion implantation method is used. The required ions are accelerated by an electric field to obtain very high energy, and then implanted into the surface of the solid material to a certain depth to form a hard phase on the surface of the aluminum alloy. The aluminum element reacts to form an intermetallic compound, and the hardness of the compound is much higher than that of the aluminum alloy matrix, which can significantly improve the surface hardness and greatly enhance the wear resistance. In Example 4, on the basis of Example 3, before ion implantation, the aluminum substrate is scanned to facilitate more uniform ion implantation. Comparing Example 1 with Example 4, annealing treatment of the aluminum substrate is added to reduce the internal stress of the aluminum substrate, adjust the organizational structure of the aluminum alloy, refine or homogenize its grains, and prevent deformation and fracture.

[0024] The above examples are only used to illustrate rather than limit the technical embodiments of the present invention. Those skilled in the relevant art can make reasonable modifications or equivalent replacements to the present invention. However, any modification and partial replacement that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

[0025] The content not detailedly described in this specification belongs to the prior art well-known to those skilled in the art.

Claims

1. A method for anodizing the surface of an aluminum substrate, characterized in that: The method for anodizing the surface of an aluminum substrate comprises the following steps: S1: Cleaning, using alkaline solution to remove oil and impurities on the surface of the aluminum substrate; S2: pickling, immersing the aluminum substrate in an acidic solution to remove the oxide scale and oxide on the surface; S3: preparing an electrolyte, mixing oxalic acid, sulfuric acid, and malonic acid in proportion to prepare an electrolyte; S4: The aluminum substrate is used as an anode and placed in an electrolyte, and an electric current is applied to form an oxide film on the surface of the aluminum substrate; S5: placing the colored aluminum substrate into a sealing liquid to seal the micropores of the oxide film to improve its corrosion resistance and wear resistance; S6: Clean the aluminum substrate with clean water to remove the residual sealing agent; S7: Scan the oxide film surface uniformly to ensure that the entire surface receives uniform ion implantation; S8: Select ions for implantation. The ion implantation equipment generates a high-energy ion beam. The implanted ions will collide and react with the atoms in the oxide film to increase the hardness of the oxide film. S9: Perform low-temperature annealing to eliminate some of the internal stress generated during the ion implantation process and make the structure of the oxide film more stable.

2. The method for anodizing the surface of an aluminum substrate according to claim 1, characterized in that: In step S1, the alkaline solution is any one of a sodium hydroxide solution, a sodium carbonate solution, a sodium tricarbonate solution, and a sodium silicate solution.

3. The method for anodizing the surface of an aluminum substrate according to claim 1, characterized in that: In step S2, the acidic solution for pickling is any one of sulfuric acid, hydrochloric acid and phosphoric acid, and the pickling temperature is 25-30° C. and the pickling time is 30-35 minutes.

4. The method for anodizing the surface of an aluminum substrate according to claim 1, characterized in that: In step S3, the concentration of sulfuric acid is 15% - 20%, the concentration of oxalic acid is 2% - 5%, and the concentration of malonic acid is 1% - 3%.

5. The method for anodizing the surface of an aluminum substrate according to claim 1, characterized in that: In step S3, the ratio of sulfuric acid, oxalic acid and malonic acid is 18:3:

2.

6. The method for anodizing the surface of an aluminum substrate according to claim 1, characterized in that: In step S4, the electrolysis time is 20-25 minutes, and the electrolysis voltage is 15-20V.

7. The method for anodizing the surface of an aluminum substrate according to claim 1, characterized in that: In step S8, ion implantation is performed with an energy of 40-50 keV and an implantation dose of 1×10¹ 5 -1×10¹ 6 ions / cm², the pressure of ion implantation is 10⁻ 4 - 10⁻ 6 Pa.

8. The method for anodizing the surface of an aluminum substrate according to claim 1, characterized in that: In the step S8, any one of the metal elements Ti, Cr and Zr is selected for ion implantation.

9. The method for anodizing the surface of an aluminum substrate according to claim 7, characterized in that: In the step S9, the annealing temperature is 200-250°C, the annealing time is 2-3 hours, the heating rate is controlled at 10-50°C / hour, and the cooling rate can be controlled at 10-20°C / hour.

10. The method for anodizing the surface of an aluminum substrate according to claim 1, characterized in that: In the step S9, the annealing atmosphere is either nitrogen or argon to prevent the aluminum alloy from being oxidized during the annealing process.

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