Surface treatment process for corrosion-resistant superhard aviation aluminum material

Abstract

The invention belongs to the technical field of surface treatment of aluminum materials, and particularly relates to a surface treatment process of a corrosion-resistant superhard aviation aluminum material, which comprises the following specific steps: firstly, soaking the aluminum material in degreasing fluid, and then washing the aluminum material with clear water; after cleaning, the surface of the aluminum material is subjected to alkali washing with a sodium hydroxide solution and then thoroughly washed with clear water; after the aluminum material is washed clean, aluminum oxide sand particles with the particle size ranging from 0.1 mm to 0.3 mm are evenly sprayed to the surface of the aluminum material, so that a uniform rough surface with the Ra ranging from 0.5 micrometer to 0.8 micrometer is formed; after spraying, firstly carrying out acid pickling neutralization by adopting a nitric acid solution, and then washing with deionized water; and after washing, the pretreated aluminum material serves as an anode, a stainless steel plate serves as a cathode, the aluminum material and the stainless steel plate are put into a micro-arc oxidation tank containing an electrolyte solution, then a power source is switched on, and treatment is conducted according to set technological parameters. According to the method, the ceramic membrane is generated on the surface of the aluminum material, so that the microhardness of the membrane layer is greatly improved, and permeation paths of corrosive media such as chloride ions and water molecules are effectively blocked.

Description

Technical Field

[0001] This invention relates to the field of aluminum surface treatment technology, specifically to the surface treatment process of corrosion-resistant, ultra-hard aerospace aluminum materials. Background Technology

[0002] In the aerospace industry, ultra-hard aerospace aluminum, due to its high strength and low density, has become an important material for manufacturing key components such as aircraft structural parts and skin. With the continuous development of aerospace technology, the service requirements for aircraft in various complex environments are increasingly stringent. Especially in harsh environments such as marine climates, high humidity, and strong ultraviolet radiation, aluminum surfaces are highly susceptible to corrosion, thus affecting aircraft safety and service life. Therefore, effective surface treatment of corrosion-resistant ultra-hard aerospace aluminum to improve its corrosion resistance and overall performance has become one of the key technologies in the aerospace manufacturing field.

[0003] However, current surface treatment methods have the following problems: 1. Shortcomings of Traditional Anodizing: Traditional anodizing is a common method for surface treatment of aerospace aluminum materials, improving corrosion resistance by forming an oxide film on the aluminum surface. However, this method has some problems. For example, the oxide film has high porosity, allowing corrosive media such as chloride ions and water molecules to easily penetrate the substrate through the pores during long-term service, leading to film peeling and substrate corrosion. Taking the aluminum alloy skin of a certain type of aircraft as an example, after traditional anodizing treatment, localized corrosion spots appeared on the surface after a period of flight in coastal areas. Further inspection revealed pitting corrosion in the substrate under the oxide film, severely affecting the structural strength and appearance of the skin.

[0004] 2. Coating-substrate adhesion issues: In some surface treatment processes, such as spraying organic coatings, insufficient adhesion between the coating and the aluminum substrate is a common problem. Because a dense oxide film easily forms on the aluminum surface, improper pretreatment can prevent the coating from bonding firmly to the substrate. During aircraft flight, factors such as vibration and temperature changes can cause the coating to peel or crack, thus losing its protective function for the substrate.

[0005] 3. Challenges posed by environmental protection requirements: With increasingly stringent environmental regulations, some agents containing heavy metals and volatile organic compounds used in traditional surface treatment processes are subject to restrictions. For example, in the electroless nickel plating process, the commonly used reducing agent sodium hypophosphite generates phosphorus-containing wastewater, which can pollute the environment if not properly treated. Furthermore, some anodizing processes using sulfuric acid, chromic acid, and other agents also require strict wastewater treatment, increasing production costs and environmental pressure.

[0006] Based on the above, a surface treatment process for corrosion-resistant, ultra-hard aerospace aluminum materials is invented. Summary of the Invention

[0007] To address the aforementioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution: The surface treatment process for corrosion-resistant, ultra-hard aerospace aluminum materials includes the following specific steps: S1, Preprocessing: S11, Degreasing treatment: First, immerse the aluminum material in the degreasing solution, then rinse it clean with water; S12, Alkaline washing treatment: First, use sodium hydroxide solution to perform alkaline washing on the surface of the aluminum material, and then rinse thoroughly with clean water; S13, Sandblasting roughening treatment: Alumina sand particles with a diameter of 0.1-0.3mm are uniformly sprayed onto the surface of the aluminum material to form a uniform rough surface with Ra0.5-0.8μm; S14, pickling and neutralization: First, use nitric acid solution for pickling and neutralization, then rinse thoroughly with deionized water; S2, Surface treatment: S21, Micro-arc oxidation treatment: First, the pre-treated aluminum material is used as the anode and the stainless steel plate is used as the cathode. The two materials are placed in a micro-arc oxidation tank containing an electrolyte solution. Then, the power is turned on and the process is carried out according to the set process parameters. S22, Sealing treatment: Immerse the aluminum material in deionized water; S23, Composite Coating Treatment: S231, Under-layer treatment: First, immerse the aluminum material in the conversion solution, then rinse it with clean water to obtain a chromium-free conversion film; S232, silane coupling agent transition layer: The coupling agent solution is applied by dip coating or spray coating and reacted at room temperature for 5-8 minutes; S233, Intermediate Layer Spraying: The epoxy primer is evenly sprayed onto the surface of the conversion film using a spraying process; S224, Topcoat spraying: Polyurethane topcoat is sprayed onto the primer surface using a spraying process.

[0008] As a preferred embodiment of the surface treatment process for corrosion-resistant ultra-hard aerospace aluminum materials described in this invention, wherein: the immersion temperature in S11 is 50-60℃ and the immersion time is 10-15 minutes; the sodium hydroxide solution concentration in S12 is 50-80g / L, the sodium hydroxide solution temperature is 40-50℃, and the alkaline washing time is 5-10 minutes.

[0009] As a preferred embodiment of the surface treatment process for corrosion-resistant ultra-hard aerospace aluminum materials described in this invention, wherein: in S13, the sandblasting pressure is 0.4-0.6MPa, the sandblasting distance is 15-20cm, and the sandblasting time is 1-2 minutes; in S14, the concentration of nitric acid solution is 100-150g / L, the temperature of nitric acid solution is room temperature, and the nitric acid time is 3-5 minutes.

[0010] As a preferred embodiment of the surface treatment process for corrosion-resistant ultra-hard aerospace aluminum materials described in this invention, the process parameters in S21 include a power supply voltage of 300-400V, a pulse frequency of 50-100Hz, a duty cycle of 20%-30%, a processing time of 20-30 minutes, and an electrolyte solution temperature of 20-30℃.

[0011] As a preferred embodiment of the surface treatment process for corrosion-resistant and ultra-hard aerospace aluminum materials described in this invention, the raw materials of the electrolyte solution in S21 include, by weight, 25-30 parts sodium silicate, 25-30 parts sodium aluminate, 10-15 parts sodium carbonate, 10-15 parts sodium phosphate, 10-15 parts sodium hydroxide, and 60-70 parts deionized water.

[0012] As a preferred embodiment of the surface treatment process for corrosion-resistant ultra-hard aerospace aluminum materials described in this invention, the immersion temperature in S22 is 80-90℃ and the immersion time is 15-20 minutes.

[0013] As a preferred embodiment of the surface treatment process for corrosion-resistant ultra-hard aerospace aluminum materials described in this invention, wherein: the immersion temperature in S231 is room temperature, and the immersion time is 5-10 minutes; the raw materials of the conversion solution include, by weight: 10-15 parts potassium fluorozirconate, 10-15 parts potassium fluorotitanate, 2-4 parts ammonium bifluoride, 2-4 parts oxalic acid, 2-4 parts nitric acid, 2-4 parts potassium sodium tartrate, and 30-40 parts deionized water.

[0014] As a preferred embodiment of the surface treatment process for the corrosion-resistant, ultra-hard aerospace aluminum material described in this invention, the preparation steps of the coupling agent solution in S232 are as follows: Step 1: Dissolve γ-aminopropyltriethoxysilane in deionized water, with a volume ratio of γ-aminopropyltriethoxysilane to deionized water of 1:99; Step 2: Add 0.1% glacial acetic acid to adjust the pH to 4.5-5.0 to prepare a 1% coupling agent solution.

[0015] As a preferred embodiment of the surface treatment process for corrosion-resistant ultra-hard aerospace aluminum materials described in this invention, the coating thickness in S233 is set to 20-30μm, and the spray gun pressure is set to 0.3-0.5MPa and the spraying distance is set to 20-30cm during spraying.

[0016] As a preferred embodiment of the surface treatment process for the corrosion-resistant ultra-hard aerospace aluminum material described in this invention, the coating thickness in S234 is set to 30-40μm, and the spray gun pressure is set to 0.3-0.5MPa and the spraying distance is set to 20-30cm during spraying.

[0017] Compared with existing technologies: 1. Advantages of solutions for high porosity in traditional anodizing Improved density of ceramic film: By generating a ceramic film on the surface of aluminum, the microhardness of the film is greatly improved, and the penetration path of corrosive media such as chloride ions and water molecules is effectively blocked. Dual sealing protection: By combining the natural porosity of the micro-arc oxidation film with that of the traditional oxide film, which is lower than that of the traditional oxide film, with the hot water sealing process, the hydroxide fills the pores, which greatly reduces the porosity. 2. Breakthrough design to address insufficient coating adhesion Nanoscale interface anchoring: The chromium-free conversion film formed through the bottom treatment provides mechanical bonding sites for the primer; at the same time, the -OH and -COOH groups contained in the conversion film chemically bond with the epoxy groups of the epoxy primer, thereby greatly improving the adhesion. Gradient modulus transition: By setting an epoxy primer between the conversion film and the topcoat, a modulus gradient buffer layer is formed, which can reduce stress concentration inside the coating and prevent cracking when the component is subjected to temperature cycling. 3. Green process systems to comply with environmental regulations Pretreatment to remove heavy metals: The sodium hydroxide-nitric acid system is used to replace the traditional alkaline etching solution containing chromic acid, reducing the total chromium content in the wastewater from 50 mg / L in the traditional process to below the detection limit. Harmless surface treatment: The micro-arc oxidation electrolyte is free of fluorides and heavy metal ions. The gas generated during electrolysis is released after being adsorbed by activated carbon, which complies with the EU REACH regulations. The composite coating system uses water-based epoxy primer and polyurethane topcoat, which can reduce VOC emissions compared with solvent-based coatings. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below. Example 1:

[0019] This invention provides a surface treatment process for corrosion-resistant, ultra-hard aerospace aluminum materials, including the following specific steps: S1, Preprocessing: S11, Degreasing treatment: First, immerse the aluminum material in a degreasing solution (including but not limited to water-based degreasing agent), and then rinse it with clean water to remove grease, oil stains and other contaminants from the surface of the aluminum material; the immersion temperature is 50℃ and the immersion time is 10 minutes. S12, Alkaline washing treatment: First, use sodium hydroxide solution to perform alkaline washing on the aluminum surface to remove the natural oxide film and other impurities on the surface, and then rinse thoroughly with clean water to prevent alkaline residue; wherein, the concentration of sodium hydroxide solution is 50g / L, the temperature of sodium hydroxide solution is 40℃, and the alkaline washing time is 5 minutes; S13, Sandblasting roughening treatment: Alumina abrasive particles with a diameter of 0.1 mm are uniformly sprayed onto the surface of the aluminum material to form a uniform rough surface with a diameter of Ra 0.5 μm; wherein, the sandblasting pressure is 0.4 MPa, the sandblasting distance is 15 cm, and the sandblasting time is 1 minute; S14, pickling and neutralization: First, use nitric acid solution for pickling and neutralization to remove residual alkali and surface metal ions after alkaline washing, so that the aluminum surface presents a uniform activated state. Then, rinse it clean with deionized water. The concentration of nitric acid solution is 100g / L, the temperature of nitric acid solution is room temperature, and the nitric acid time is 3 minutes. S2, Surface treatment: S21, Micro-arc oxidation treatment: First, the pre-treated aluminum material is used as the anode and the stainless steel plate as the cathode, and then placed in a micro-arc oxidation tank containing an electrolyte solution. Next, the power is turned on, and the treatment is carried out according to the set process parameters to form a dense and hard ceramic film. This film has excellent corrosion resistance, wear resistance, and high temperature resistance. During the treatment, the solution is stirred regularly to ensure uniform composition. The process parameters include a power supply voltage of 300V, a pulse frequency of 50Hz, a duty cycle of 20%, a treatment time of 20 minutes, and an electrolyte solution temperature of 20℃. The raw materials of the electrolyte solution include, by weight, 25 parts sodium silicate, 25 parts sodium aluminate, 10 parts sodium carbonate, 10 parts sodium phosphate, 10 parts sodium hydroxide, and 60 parts deionized water. S22, Sealing treatment: The aluminum material is immersed in deionized water, which reacts with the oxides in the micro-arc oxidation film to generate hydroxides, which fill the pores and improve the corrosion resistance of the film. The immersion temperature is 80℃ and the immersion time is 15 minutes. S23, Composite Coating Treatment: S231, Sub-base treatment: First, immerse the aluminum material in the conversion solution, then rinse it with clean water to obtain a chromium-free conversion film; wherein, the immersion temperature is room temperature and the immersion time is 5 minutes; the raw materials of the conversion solution include, by weight: 10 parts potassium fluorozirconate, 10 parts potassium fluorotitanate, 2 parts ammonium bifluoride, 2 parts oxalic acid, 2 parts nitric acid, 2 parts potassium sodium tartrate, and 30 parts deionized water; S232, Silane Coupling Agent Transition Layer: After the conversion membrane is washed and dried, the coupling agent solution is applied by dip coating or spray coating and reacted at room temperature for 5 minutes; the preparation steps of the coupling agent solution are as follows: Step 1: Dissolve γ-aminopropyltriethoxysilane in deionized water, with a volume ratio of γ-aminopropyltriethoxysilane to deionized water of 1:99; Step 2: Add 0.1% glacial acetic acid to adjust the pH to 4.5 to prepare a 1% coupling agent solution; S233, Intermediate layer spraying: The epoxy primer is uniformly sprayed onto the surface of the conversion film using a spraying process; the coating thickness is set to 20μm, and the spray gun pressure is set to 0.3MPa and the spraying distance is set to 20cm during spraying. S224, Topcoat spraying: Polyurethane topcoat is sprayed onto the primer surface using a spraying process; wherein, the coating thickness is set to 30μm, and the spray gun pressure is set to 0.3MPa and the spraying distance is set to 20cm during spraying. Example 2:

[0020] This invention provides a surface treatment process for corrosion-resistant, ultra-hard aerospace aluminum materials, including the following specific steps: S1, Preprocessing: S11, Degreasing treatment: First, immerse the aluminum material in a degreasing solution (including but not limited to water-based degreasing agent), and then rinse it with clean water to remove grease, oil stains and other contaminants from the surface of the aluminum material; the immersion temperature is 55℃ and the immersion time is 12.5 minutes. S12, Alkaline washing treatment: First, use sodium hydroxide solution to perform alkaline washing on the aluminum surface to remove the natural oxide film and other impurities on the surface, and then rinse thoroughly with clean water to prevent alkaline residue; wherein, the concentration of sodium hydroxide solution is 65g / L, the temperature of sodium hydroxide solution is 45℃, and the alkaline washing time is 7.5 minutes; S13, Sandblasting roughening treatment: Alumina abrasive particles with a diameter of 0.2 mm are uniformly sprayed onto the surface of the aluminum material to form a uniform rough surface with a diameter of Ra 0.65 μm; wherein, the sandblasting pressure is 0.5 MPa, the sandblasting distance is 17.5 cm, and the sandblasting time is 1.5 minutes; S14, pickling and neutralization: First, use nitric acid solution for pickling and neutralization to remove residual alkali and metal ions from the surface after alkaline washing, so that the aluminum surface presents a uniform activated state. Then, rinse it clean with deionized water. The concentration of nitric acid solution is 125g / L, the temperature of nitric acid solution is room temperature, and the nitric acid time is 4 minutes. S2, Surface treatment: S21, Micro-arc oxidation treatment: First, the pre-treated aluminum material is used as the anode and the stainless steel plate as the cathode, and then placed in a micro-arc oxidation tank containing an electrolyte solution. Next, the power is turned on, and the treatment is carried out according to the set process parameters to form a dense and hard ceramic film. This film has excellent corrosion resistance, wear resistance, and high-temperature resistance. During the treatment, the solution is stirred regularly to ensure uniform composition. The process parameters include a power supply voltage of 350V, a pulse frequency of 75Hz, a duty cycle of 25%, a treatment time of 25 minutes, and an electrolyte solution temperature of 25℃. The electrolyte solution contains, by weight, 27.5 parts sodium silicate, 27.5 parts sodium aluminate, 12.5 parts sodium carbonate, 12.5 parts sodium phosphate, 12.5 parts sodium hydroxide, and 65 parts deionized water. S22, Sealing treatment: The aluminum material is immersed in deionized water, which reacts with the oxides in the micro-arc oxidation film to generate hydroxides, which fill the pores and improve the corrosion resistance of the film. The immersion temperature is 85℃ and the immersion time is 17.5 minutes. S23, Composite Coating Treatment: S231, Underlying treatment: First, immerse the aluminum material in the conversion solution, then rinse it with clean water to obtain a chromium-free conversion film; wherein, the immersion temperature is room temperature, and the immersion time is 7.5 minutes; the raw materials of the conversion solution include, by weight: 12.5 parts potassium fluorozirconate, 12.5 parts potassium fluorotitanate, 3 parts ammonium bifluoride, 3 parts oxalic acid, 3 parts nitric acid, 3 parts potassium sodium tartrate, and 35.5 parts deionized water; S232, Silane Coupling Agent Transition Layer: After the conversion membrane is washed and dried, the coupling agent solution is applied by dip coating or spray coating, and reacted at room temperature for 6.5 minutes; the preparation steps of the coupling agent solution are as follows: Step 1: Dissolve γ-aminopropyltriethoxysilane in deionized water, with a volume ratio of γ-aminopropyltriethoxysilane to deionized water of 1:99; Step 2: Add 0.1% glacial acetic acid to adjust the pH to 4.75 to prepare a 1% coupling agent solution; S233, Intermediate Layer Spraying: The epoxy primer is uniformly sprayed onto the surface of the conversion film using a spraying process; the coating thickness is set to 25μm, and the spray gun pressure is set to 0.4MPa and the spraying distance is set to 25cm during spraying. S224, Topcoat spraying: Polyurethane topcoat is sprayed onto the primer surface using a spraying process; wherein, the coating thickness is set to 35μm, and the spray gun pressure is set to 0.4MPa and the spraying distance is set to 25cm during spraying. Example 3:

[0021] This invention provides a surface treatment process for corrosion-resistant, ultra-hard aerospace aluminum materials, including the following specific steps: S1, Preprocessing: S11, Degreasing treatment: First, immerse the aluminum material in a degreasing solution (including but not limited to water-based degreasing agent), and then rinse it with clean water to remove grease, oil stains and other contaminants from the surface of the aluminum material; the immersion temperature is 60℃ and the immersion time is 15 minutes. S12, Alkaline washing treatment: First, use sodium hydroxide solution to perform alkaline washing on the aluminum surface to remove the natural oxide film and other impurities on the surface, and then rinse thoroughly with clean water to prevent alkaline residue; wherein, the concentration of sodium hydroxide solution is 80g / L, the temperature of sodium hydroxide solution is 50℃, and the alkaline washing time is 10 minutes. S13, Sandblasting roughening treatment: Alumina abrasive particles with a diameter of 0.3 mm are uniformly sprayed onto the surface of the aluminum material to form a uniform rough surface with a diameter of Ra 0.8 μm; wherein, the sandblasting pressure is 0.6 MPa, the sandblasting distance is 20 cm, and the sandblasting time is 2 minutes. S14, pickling and neutralization: First, use nitric acid solution for pickling and neutralization to remove residual alkali and metal ions on the surface after alkaline washing, so that the aluminum surface presents a uniform activated state. Then, rinse it clean with deionized water. The concentration of nitric acid solution is 150g / L, the temperature of nitric acid solution is room temperature, and the nitric acid time is 5 minutes. S2, Surface treatment: S21, Micro-arc oxidation treatment: First, the pre-treated aluminum material is used as the anode and the stainless steel plate as the cathode, and then placed in a micro-arc oxidation tank containing an electrolyte solution. Next, the power is turned on, and the treatment is carried out according to the set process parameters to form a dense and hard ceramic film. This film has excellent corrosion resistance, wear resistance, and high-temperature resistance. During the treatment, the solution is stirred regularly to ensure uniform composition. The process parameters include a power supply voltage of 400V, a pulse frequency of 100Hz, a duty cycle of 30%, a treatment time of 30 minutes, and an electrolyte solution temperature of 30℃. The electrolyte solution consists of 30 parts sodium silicate, 30 parts sodium aluminate, 15 parts sodium carbonate, 15 parts sodium phosphate, 15 parts sodium hydroxide, and 70 parts deionized water by weight. S22, Sealing treatment: The aluminum material is immersed in deionized water, which reacts with the oxides in the micro-arc oxidation film to generate hydroxides, which fill the pores and improve the corrosion resistance of the film. The immersion temperature is 90℃ and the immersion time is 20 minutes. S23, Composite Coating Treatment: S231, Substrate treatment: First, immerse the aluminum material in the conversion solution, then rinse it with clean water to obtain a chromium-free conversion film; wherein, the immersion temperature is room temperature and the immersion time is 10 minutes; the raw materials of the conversion solution include, by weight: 15 parts potassium fluorozirconate, 15 parts potassium fluorotitanate, 4 parts ammonium bifluoride, 4 parts oxalic acid, 4 parts nitric acid, 4 parts potassium sodium tartrate, and 40 parts deionized water. S232, Silane Coupling Agent Transition Layer: After the conversion membrane is washed and dried, the coupling agent solution is applied by dip coating or spray coating and reacted at room temperature for 8 minutes; the preparation steps of the coupling agent solution are as follows: Step 1: Dissolve γ-aminopropyltriethoxysilane in deionized water, with a volume ratio of γ-aminopropyltriethoxysilane to deionized water of 1:99; Step 2: Add 0.1% glacial acetic acid to adjust the pH to 5.0 to prepare a 1% coupling agent solution; S233, Intermediate layer spraying: The epoxy primer is uniformly sprayed onto the surface of the conversion film using a spraying process; the coating thickness is set to 30μm, and the spray gun pressure is set to 0.5MPa and the spraying distance is set to 30cm during spraying. S224, Topcoat spraying: Polyurethane topcoat is sprayed onto the primer surface using a spraying process; wherein, the coating thickness is set to 40μm, and the spray gun pressure is set to 0.5MPa and the spraying distance is set to 30cm.

[0022] By comparing the surface treatment processes performed in Examples 1-3 above, the following data were obtained: Example 1 Example 2 Example 3 Microhardness (HV) 800-900 900-1000 800-900 Porosity 5%-8% 4%-6% 6%-8% Film density (g / cm³) 3.0-3.2 3.2-3.4 3.1-3.2 As can be seen from the table above, the surface treatment processes carried out in Examples 1-3 all showed good performance in terms of microhardness, porosity and film density. After use, Example 2 showed the best results.

[0023] Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, as long as there is no structural conflict, the features in the disclosed embodiments can be combined with each other in any manner. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A surface treatment process for corrosion-resistant, ultra-hard aerospace aluminum, characterized in that, The specific steps are as follows: S1, Preprocessing: S11, Degreasing treatment: First, immerse the aluminum material in the degreasing solution, then rinse it clean with water; S12, Alkaline washing treatment: First, use sodium hydroxide solution to perform alkaline washing on the surface of the aluminum material, and then rinse thoroughly with clean water; S13, Sandblasting roughening treatment: Alumina sand particles with a diameter of 0.1-0.3mm are uniformly sprayed onto the surface of the aluminum material to form a uniform rough surface with Ra0.5-0.8μm; S14, pickling and neutralization: First, use nitric acid solution for pickling and neutralization, then rinse thoroughly with deionized water; S2, Surface treatment: S21, Micro-arc oxidation treatment: First, the pre-treated aluminum material is used as the anode and the stainless steel plate is used as the cathode. The two materials are placed in a micro-arc oxidation tank containing an electrolyte solution. Then, the power is turned on and the process is carried out according to the set process parameters. S22, Sealing treatment: Immerse the aluminum material in deionized water; S23, Composite Coating Treatment: S231, Under-layer treatment: First, immerse the aluminum material in the conversion solution, then rinse it with clean water to obtain a chromium-free conversion film; S232, silane coupling agent transition layer: The coupling agent solution is applied by dip coating or spray coating and reacted at room temperature for 5-8 minutes; S233, Intermediate Layer Spraying: The epoxy primer is evenly sprayed onto the surface of the conversion film using a spraying process; S224, Topcoat spraying: Polyurethane topcoat is sprayed onto the primer surface using a spraying process.

2. The surface treatment process for corrosion-resistant, ultra-hard aerospace aluminum materials according to claim 1, characterized in that, The soaking temperature in S11 is 50-60℃, and the soaking time is 10-15 minutes; the sodium hydroxide solution concentration in S12 is 50-80 g / L, the sodium hydroxide solution temperature is 40-50℃, and the alkaline washing time is 5-10 minutes.

3. The surface treatment process for corrosion-resistant, ultra-hard aerospace aluminum materials according to claim 1, characterized in that, In S13, the sandblasting pressure is 0.4-0.6 MPa, the sandblasting distance is 15-20 cm, and the sandblasting time is 1-2 minutes; in S14, the nitric acid solution concentration is 100-150 g / L, the nitric acid solution temperature is room temperature, and the nitric acid time is 3-5 minutes.

4. The surface treatment process for corrosion-resistant, ultra-hard aerospace aluminum materials according to claim 1, characterized in that, The process parameters in S21 include a power supply voltage of 300-400V, a pulse frequency of 50-100Hz, a duty cycle of 20%-30%, a processing time of 20-30 minutes, and an electrolyte solution temperature of 20-30℃.

5. The surface treatment process for corrosion-resistant, ultra-hard aerospace aluminum materials according to claim 1, characterized in that, The raw materials of the electrolyte solution in S21 include, by weight, 25-30 parts sodium silicate, 25-30 parts sodium aluminate, 10-15 parts sodium carbonate, 10-15 parts sodium phosphate, 10-15 parts sodium hydroxide, and 60-70 parts deionized water.

6. The surface treatment process for corrosion-resistant, ultra-hard aerospace aluminum materials according to claim 1, characterized in that, The soaking temperature in S22 is 80-90℃, and the soaking time is 15-20 minutes.

7. The surface treatment process for corrosion-resistant, ultra-hard aerospace aluminum materials according to claim 1, characterized in that, The soaking temperature in S231 is room temperature, and the soaking time is 5-10 minutes; the raw materials of the conversion solution include, by weight: 10-15 parts potassium fluorozirconate, 10-15 parts potassium fluorotitanate, 2-4 parts ammonium bifluoride, 2-4 parts oxalic acid, 2-4 parts nitric acid, 2-4 parts potassium sodium tartrate, and 30-40 parts deionized water.

8. The surface treatment process for corrosion-resistant, ultra-hard aerospace aluminum materials according to claim 1, characterized in that, The preparation steps of the coupling agent solution in S232 are as follows: Step 1: Dissolve γ-aminopropyltriethoxysilane in deionized water, with a volume ratio of γ-aminopropyltriethoxysilane to deionized water of 1:99; Step 2: Add 0.1% glacial acetic acid to adjust the pH to 4.5-5.0 to prepare a 1% coupling agent solution.

9. The surface treatment process for corrosion-resistant, ultra-hard aerospace aluminum materials according to claim 1, characterized in that, In S233, the coating thickness is set to 20-30μm, and during spraying, the spray gun pressure is set to 0.3-0.5MPa, and the spraying distance is set to 20-30cm.

10. The surface treatment process for corrosion-resistant, ultra-hard aerospace aluminum materials according to claim 1, characterized in that, In S234, the coating thickness is set to 30-40μm, and during spraying, the spray gun pressure is set to 0.3-0.5MPa, and the spraying distance is set to 20-30cm.