Preparation method of micro-arc oxidation composite film layer on surface of aluminum alloy component

Abstract

The preparation method of the micro-arc oxidation composite film layer on the surface of the aluminum alloy part comprises the step that the surface of the aluminum alloy part is pretreated, so that an oxidation layer on the surface of the aluminum alloy is polished to be clean. The micro-arc oxidation film is prepared on the surface of the pretreated aluminum alloy part, then the chemical conversion film is prepared on the aluminum alloy part with the micro-arc oxidation film, and therefore the chemical conversion film is generated in gaps of the micro-arc oxidation film, blocking of the gaps of the micro-arc oxidation film is achieved, the protection strength of the micro-arc oxidation film is improved, and the service life of the micro-arc oxidation film is prolonged. And a corrosion medium is prevented from entering from a gap of the micro-arc oxidation film and corroding the aluminum alloy part. And then, an electrophoresis paint film is prepared on the aluminum alloy part prepared with the micro-arc oxidation film and the chemical conversion film, and finally, the electrophoresis paint film is dried. And gaps of the micro-arc oxidation film are further blocked through the electrophoresis paint film, protection of the surface of the aluminum alloy part is enhanced, and the corrosion resistance of the aluminum alloy part is greatly improved.

Description

Technical Field

[0001] This application relates to the field of aluminum alloy component surface processing technology, and in particular to a method for preparing a micro-arc oxidation composite film on the surface of aluminum alloy components. Background Technology

[0002] Aluminum and its alloys have the advantages of low density, good processability, high specific strength and good thermal conductivity, so they are widely used in aerospace, automobile, 3C products, construction and other fields, but their corrosion resistance is not high.

[0003] In natural environments, a layer of oxide film forms on the surface of pure aluminum. This oxide film has poor corrosion resistance and weak adhesion to coatings. Furthermore, pure aluminum has limited strength. By adding different elements to aluminum to create aluminum alloys, the strength and overall performance of pure aluminum can be improved to meet different application requirements. However, the introduction of other elements leads to the formation of various second-phase intermetallic compound particles, making the alloys susceptible to pitting corrosion and intergranular corrosion.

[0004] To improve the surface properties of aluminum alloy components, this application provides a method for preparing a micro-arc oxidation composite film on the surface of aluminum alloy components. Summary of the Invention

[0005] This application provides a method for preparing a micro-arc oxidation composite film on the surface of an aluminum alloy component, which is used to treat the surface of the aluminum alloy component.

[0006] This application provides a method for preparing a micro-arc oxidation composite film on the surface of an aluminum alloy component, including:

[0007] Pre-treat the surface of aluminum alloy parts;

[0008] A micro-arc oxide film is prepared on the surface of the pretreated aluminum alloy parts;

[0009] Chemical conversion films are prepared on aluminum alloy parts with micro-arc oxidation films.

[0010] Electrophoretic coating film is prepared on aluminum alloy parts with micro-arc oxidation film and chemical conversion film.

[0011] The electrophoretic coating film is dried.

[0012] In one feasible implementation, the pretreatment of the aluminum alloy component surface includes:

[0013] The surface of the aluminum alloy parts was polished smooth using metallographic sandpaper of 600 grit, 1000 grit, 1500 grit and 2000 grit, and then the surface of the aluminum alloy parts was cleaned with pure water.

[0014] In one feasible implementation, the preparation of a micro-arc oxide film on the surface of the pretreated aluminum alloy component includes:

[0015] The aluminum alloy component is placed in a micro-arc oxidation solution and connected to the anode electrode. Stainless steel is used as the cathode to perform micro-arc oxidation treatment on the aluminum alloy component to form a micro-arc oxidation film on the surface of the aluminum alloy component.

[0016] In one feasible implementation, the preparation of the chemical conversion film on the surface of the micro-arc oxidation film includes:

[0017] Aluminum alloy parts with micro-arc oxide films on their surfaces are immersed in a chemical conversion solution for treatment.

[0018] In one feasible implementation, the preparation of an electrophoretic coating film on the surface of a chemical conversion film includes:

[0019] An aluminum alloy component with a chemical conversion film on its surface is placed into an electrophoretic coating. The aluminum alloy component is used as the cathode and stainless steel as the anode for electrophoretic treatment, and an electrophoretic coating film is prepared on the surface of the chemical conversion film.

[0020] In one feasible implementation, the micro-arc oxidation solution comprises silicate in a concentration range of 5 g / L to 35 g / L, citrate in a concentration range of 5 g / L to 25 g / L, and phosphoric acid in a concentration range of 2 g / L to 30 g / L.

[0021] In one feasible implementation, a constant current mode is used during the preparation of the micro-arc oxide film on the surface of the aluminum alloy component, with a current density range of 0.2 A / dm². 2 ~1.5A / dm 2 The voltage range is 400V to 600V, the frequency range is 100Hz to 1000Hz, the duty cycle range is 20% to 80%, the processing time range is 20min to 120min, and the electrolyte temperature range is 15℃ to 30℃.

[0022] In one feasible implementation, the chemical conversion solution comprises cerium nitrate at a concentration of 0.05 mol / L, hydrogen peroxide at a concentration of 0.6 mol / L, and sodium chloride at a concentration of 0.05 mol / L.

[0023] In one feasible implementation, the temperature range of the chemical conversion solution is 20℃-60℃, and the immersion time of the aluminum alloy in the chemical conversion solution is 10min-30min.

[0024] In one feasible implementation, the electrophoretic coating comprises pigment, epoxy emulsion and water, wherein the ratio of the three components is 2-5:3-6:4-8;

[0025] And / or, during the electrophoresis process, the voltage range is 80V to 100V, and the processing time ranges from 5min to 10min.

[0026] This application provides a method for preparing a micro-arc oxidation composite film on the surface of an aluminum alloy component, comprising: pre-treating the surface of the aluminum alloy component to remove the oxide layer; preparing a micro-arc oxidation film on the pre-treated surface of the aluminum alloy component; then preparing a chemical conversion film on the aluminum alloy component with the micro-arc oxidation film, thereby generating a chemical conversion film in the voids of the micro-arc oxidation film, sealing the voids, improving the protective strength of the micro-arc oxidation film, and preventing corrosive media from entering and corroding the aluminum alloy component through the voids of the micro-arc oxidation film; then preparing an electrophoretic paint film on the aluminum alloy component with the micro-arc oxidation film and chemical conversion film; and finally drying the electrophoretic paint film. The electrophoretic paint film further seals the voids of the micro-arc oxidation film, enhances the protection of the aluminum alloy component surface, and greatly improves the corrosion resistance of the aluminum alloy component. Attached Figure Description

[0027] The accompanying drawings, which are provided to further illustrate the invention and constitute a part of this invention, are illustrative embodiments of the invention and their descriptions are used to explain this application and do not constitute an undue limitation of the invention.

[0028] In the attached diagram:

[0029] Figure 1 This is a schematic flowchart of a method for preparing a micro-arc oxidation composite film on the surface of an aluminum alloy component according to an embodiment of this application. Detailed Implementation

[0030] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of this application.

[0031] In the description of the embodiments of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0032] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0033] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0034] Aluminum and its alloys have the advantages of low density, good processability, high specific strength and good thermal conductivity, so they are widely used in aerospace, automobile, 3C products, construction and other fields, but their corrosion resistance is not high.

[0035] In natural environments, a layer of oxide film forms on the surface of pure aluminum. This oxide film has poor corrosion resistance and weak adhesion to coatings. Furthermore, pure aluminum has limited strength. By adding different elements to aluminum to create aluminum alloys, the strength and overall performance of pure aluminum can be improved to meet different application requirements. The introduction of other elements leads to the formation of various second-phase intermetallic compound particles, making the alloy susceptible to pitting and intergranular corrosion. Therefore, aluminum alloys typically require surface treatment to obtain excellent corrosion resistance and colorability, while also enhancing their adhesion to coatings. Micro-arc oxidation (MAO) technology utilizes arc discharge to grow ceramic oxide films in situ on the substrate surface. The film layer exhibits strong adhesion to the substrate, good toughness, high density, and excellent wear resistance, high temperature resistance, and insulation properties. However, the high-temperature and high-pressure reaction during film formation creates numerous porous structures on the surface, providing channels for corrosive media to penetrate and severely affecting the long-term protective effect of the oxide film.

[0036] To improve the surface properties of aluminum alloy components, this application provides a method for preparing a micro-arc oxidation composite film on the surface of aluminum alloy components. The solution provided by this application will be described in detail below with reference to the accompanying drawings.

[0037] Reference Figure 1As shown in the embodiments of this application, a method for preparing a micro-arc oxidation composite film on the surface of an aluminum alloy component is provided, including:

[0038] S100: Pre-treatment of the surface of aluminum alloy parts.

[0039] For example, the surface of the aluminum alloy part is polished smooth using metallographic sandpaper of 600 grit, 1000 grit, 1500 grit and 2000 grit, and the surface of the aluminum alloy part is cleaned with pure water to remove the metal oxide layer on the surface of the aluminum alloy part.

[0040] S200: Prepare a micro-arc oxide film on the surface of pretreated aluminum alloy parts.

[0041] Specifically, the aluminum alloy component is placed in a micro-arc oxidation solution and connected to the anode electrode. Stainless steel is used as the cathode to perform micro-arc oxidation treatment on the aluminum alloy component to form a micro-arc oxidation film on the surface of the aluminum alloy component.

[0042] The micro-arc oxidation solution comprises silicate with a concentration range of 5 g / L to 35 g / L, citrate with a concentration range of 5 g / L to 25 g / L, and phosphoric acid with a concentration range of 2 g / L to 30 g / L. During the preparation of the micro-arc oxidation film on the surface of the aluminum alloy parts, a constant current mode is used, with a current density range of 0.2 A / dm² to 1.5 A / dm², a voltage range of 400 V to 600 V, a frequency range of 100 Hz to 1000 Hz, a duty cycle range of 20% to 80%, a processing time range of 20 min to 120 min, and an electrolyte temperature range of 15 °C to 30 °C.

[0043] S300: Preparation of chemical conversion film on aluminum alloy parts with micro-arc oxide film.

[0044] For example, the chemical conversion solution includes cerium nitrate at a concentration of 0.05 mol / L, hydrogen peroxide at a concentration of 0.6 mol / L, and sodium chloride at a concentration of 0.05 mol / L. During the preparation of the chemical conversion film, the temperature of the chemical conversion solution ranges from 20℃ to 60℃. The aluminum alloy component with the micro-arc oxide film on its surface is immersed in the chemical conversion solution for 10 min to 30 min.

[0045] S400: Electrophoretic coating film is prepared on aluminum alloy parts with micro-arc oxidation film and chemical conversion film.

[0046] For example, when preparing an electrophoretic coating on an aluminum alloy component with a micro-arc oxidation film and a chemical conversion film, the aluminum alloy component with the chemical conversion film on its surface is placed in the electrophoretic coating. The aluminum alloy component serves as the cathode, and stainless steel as the anode, for electrophoretic treatment, thus preparing an electrophoretic coating on the surface of the chemical conversion film. The electrophoretic coating is composed of a mixture of colorant, epoxy emulsion, and water, with a ratio ranging from 2 to 5:3 to 6:4 to 8. For example, during the electrophoretic treatment, the voltage range is 80V to 100V, and the treatment time ranges from 5 minutes to 10 minutes.

[0047] S500 is used to dry the electrophoretic coating film.

[0048] For example, the aluminum alloy part with the electrophoretic coating film is moved to a forced-air drying oven, and the drying temperature range is 100℃~120℃, and the processing time range is 60min~120min, so as to cure the electrophoretic coating film.

[0049] It is readily understood that, based on the several embodiments provided in this application, those skilled in the art can combine, split, or reorganize the embodiments of this application to obtain other embodiments, none of which exceed the protection scope of this application.

[0050] The above detailed embodiments further illustrate the purpose, technical solution, and beneficial effects of the embodiments of this application. It should be understood that the above are merely specific embodiments of the embodiments of this application and are not intended to limit the protection scope of the embodiments of this application. Any modifications, equivalent substitutions, improvements, etc., made on the basis of the technical solutions of the embodiments of this application should be included within the protection scope of the embodiments of this application.

Claims

1. A method for preparing a micro-arc oxidation composite film layer on the surface of an aluminum alloy component, characterized in that, The method comprises the following steps: pre-treating the surface of the aluminum alloy part; preparing a micro-arc oxidation film on the surface of the pre-treated aluminum alloy part; preparing a chemical conversion film on the aluminum alloy part with the micro-arc oxidation film; preparing an electrophoretic paint film on the aluminum alloy part with the micro-arc oxidation film and the chemical conversion film; drying the electrophoretic paint film.

2. The method of claim 1, wherein the method further comprises the step of: The pre-treating of the surface of the aluminum alloy part comprises the following steps: ​ polishing the surface of the aluminum alloy part with 600-mesh, 1000-mesh, 1500-mesh and 2000-mesh metallographic sandpaper, and cleaning the surface of the aluminum alloy part with pure water.

3. The method of claim 1, wherein the method further comprises the step of: applying a coating layer on the surface of the aluminum alloy component. The preparing of the micro-arc oxidation film on the surface of the pre-treated aluminum alloy part comprises the following steps: immersing the aluminum alloy part in a micro-arc oxidation solution and connecting the aluminum alloy part with an anode electrode, using stainless steel as a cathode, to perform micro-arc oxidation treatment on the aluminum alloy part, so as to form a micro-arc oxidation film on the surface of the aluminum alloy part.

4. The method of claim 1, wherein the method further comprises the step of: The preparing of the chemical conversion film on the aluminum alloy part with the micro-arc oxidation film comprises the following steps: immersing the aluminum alloy part with the micro-arc oxidation film on the surface in a chemical conversion solution for immersion treatment.

5. The method of claim 1, wherein the method further comprises the step of: applying a coating layer on the surface of the aluminum alloy component. The preparing of the electrophoretic paint film on the aluminum alloy part with the micro-arc oxidation film and the chemical conversion film comprises the following steps: immersing the aluminum alloy part with the chemical conversion film on the surface in an electrophoretic coating, using the aluminum alloy part as a cathode and stainless steel as an anode, to perform electrophoretic treatment and prepare an electrophoretic paint film on the surface of the chemical conversion film.

6. The method of claim 3, wherein the method further comprises the step of: applying a coating layer on the surface of the aluminum alloy component. The micro-arc oxidation solution comprises silicate with a concentration ranging from 5 g / L to 35 g / L, citrate with a concentration ranging from 5 g / L to 25 g / L, and phosphoric acid with a concentration ranging from 2 g / L to 30 g / L.

7. The method of claim 3, wherein the method further comprises the step of: applying a coating layer on the surface of the aluminum alloy component. In the process of preparing micro-arc oxidation film on the surface of aluminum alloy parts, constant current mode is adopted, current density range is 0.2A / dm 2 ~1.5A / dm 2 , voltage range is 400V-600V, frequency range is 100Hz-1000Hz, duty cycle range is 20%-80%, processing time range is 20min-120min, electrolyte temperature range is 15℃-30℃.

8. The method of claim 4, wherein the method further comprises the step of: applying a coating layer on the surface of the aluminum alloy component. The chemical conversion solution comprises cerium nitrate with a concentration of 0.05 mol / L, hydrogen peroxide with a concentration of 0.6 mol / L, and sodium chloride with a concentration of 0.05 mol / L.

9. The method of claim 4, wherein the method further comprises the step of: applying a coating layer on the surface of the aluminum alloy component. The temperature of the chemical conversion solution ranges from 20°C to 60°C, and the immersion time of the aluminum alloy in the chemical conversion solution ranges from 10 min to 30 min.

10. The method for preparing a micro-arc oxidation composite film on the surface of an aluminum alloy component according to claim 5, characterized in that, The electrophoretic coating comprises color paste, epoxy emulsion and water, and the ratio of the three ranges from 2-5:3-6:4-8. During the electrophoretic treatment, the voltage ranges from 80 V to 100 V, and the treatment time ranges from 5 min to 10 min.

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