Method for removing over-aged film layer caused by chemical oxidation of aluminum alloy

Abstract

The invention discloses a method for removing an aluminum alloy chemical oxidation over-aged film layer, and belongs to the technical field of metal surface treatment. The method comprises the following steps: taking an aluminum alloy sample with an aged film layer as an anode, putting the aluminum alloy sample into an electrolytic cell, adding electrolyte, setting electrochemical workstation parameters, and carrying out electrochemical dissolution on the aluminum alloy sample to obtain a loose and porous aged film layer aluminum alloy sample; the loose and porous aged film layer aluminum alloy sample is put into a chemical corrosion solution to be subjected to chemical corrosion, and a corroded aluminum alloy sample is obtained; and putting the corroded aluminum alloy sample into a bright dipping solution, carrying out bright dipping treatment, taking out the aluminum alloy sample, washing the aluminum alloy sample, and blow-drying the aluminum alloy sample to complete removal of the aluminum alloy chemical oxidation over-aged film layer. Due to the combined use of electrochemical dissolution and chemical corrosion, the phenomenon of over-corrosion of parts caused by long-time corrosion is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of metal surface treatment and relates to a method for removing an over-aged film layer of aluminum alloy chemical oxidation. Background Art

[0002] As an important surface treatment technology, aluminum alloy chemical oxidation technology has a wide range of applications. It is not only often used as an effective base layer for organic polymer spraying on the surface of aluminum alloy to enhance the bonding strength between the coating and the substrate and the overall performance of the coating, but can also be used directly as the final coating of aluminum alloy to provide the necessary protection and decorative functions for aluminum alloy products. This chemical oxidation film layer has the characteristics of thin thickness (usually between 0.125 and 1.000 microns) and strong adhesion, and can resist the erosion of the external environment to a certain extent. However, with the passage of time and changes in the use environment, the aluminum alloy chemical oxidation film layer may age due to various factors such as long-term storage and high-temperature baking. After aging, the key properties of the film layer, such as corrosion resistance and bonding strength, may change, and sometimes even improve performance, but more often the performance decreases, resulting in a weakened bonding effect of the aluminum alloy substrate on the coating.

[0003] When the aluminum alloy oxide film ages to a certain extent and no longer meets the requirements of use, it needs to be removed. Traditional chemical corrosion methods for removing the film, such as alkaline corrosion and pickling, can achieve the removal of the film to a certain extent, but there are many shortcomings. For example, the corrosion rates of these methods on the same workpiece are often uneven, which makes it difficult to completely remove the film in some areas, while other areas may damage the substrate due to excessive corrosion. Especially for the over-aged aluminum alloy oxide film, due to its more complex structure and poorer stability, traditional methods require longer corrosion to remove it. However, in this way, it is easy to cause excessive corrosion of the substrate due to excessive corrosion time, which in turn causes the workpiece to be scrapped, bringing unnecessary economic losses to the company. Therefore, it is particularly important and urgent to find a new removal method that can effectively remove the aged aluminum alloy oxide film and avoid excessive corrosion of the substrate. Summary of the invention

[0004] The purpose of the present invention is to solve the technical problem of excessive corrosion caused by traditional removal methods of aluminum alloy chemical oxidation aged film in the prior art, and to provide a method for removing aluminum alloy chemical oxidation excessive aged film.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention discloses a method for removing an over-aged film layer of an aluminum alloy chemically oxidized, comprising the following steps: The aluminum alloy sample with an aged film layer is used as an anode, placed in an electrolytic cell and an electrolyte is added, and the electrochemical workstation parameters are set to electrochemically dissolve the aluminum alloy sample to obtain a loose and porous aluminum alloy sample with an aged film layer; Putting the loose and porous aged film layer aluminum alloy sample into a chemical etching solution for chemical etching to obtain a corroded aluminum alloy sample; The corroded aluminum alloy sample is placed in a polishing liquid, and after the polishing treatment, it is taken out, rinsed and blown dry to complete the removal of the over-aged film layer of the aluminum alloy chemical oxidation.

[0006] Further improvements are: Before the aluminum alloy sample is electrochemically dissolved, it is mounted and ultrasonically degreased; the mounting adopts aluminum or titanium hangers to fasten the workpiece.

[0007] The ultrasonic degreasing is specifically: Immerse the mounted aluminum alloy sample with an aged film layer in a 3% to 5% metal cleaning agent aqueous solution at 30°C to 40°C, turn on the ultrasonic cleaning machine, and clean it for 3 min to 5 min. After cleaning, use tap water to clean the metal cleaning agent aqueous solution on the sample.

[0008] The electrolyte is a sulfuric acid solution with a concentration of 200g / L-250g / L; after the electrochemical dissolution is completed, the obtained loose and porous aged film layer aluminum alloy sample is taken out and rinsed with deionized water.

[0009] The parameters of the electrochemical workstation are: current density of 1.5A / dm²-2.5A / dm², voltage of 14V-20V at room temperature; the time of the electrochemical dissolution is 2min-5min.

[0010] The chemical etching solution is a mixed solution of 35g / L-45g / L sodium hydroxide solution, 20g / L-30g / L sodium carbonate solution and 20g / L-30g / L sodium fluoride solution.

[0011] When performing the chemical etching, a magnetic stirrer is used to keep the chemical etching solution uniform.

[0012] The temperature of the chemical etching is controlled between 35° C. and 45° C., and the etching time is controlled between 60s and 120s.

[0013] The light emitting liquid is a mixed solution of 500ml / L-700ml / L nitric acid solution and 20ml / L-30ml / L sulfuric acid solution.

[0014] The light extraction treatment is carried out at room temperature, and the treatment time does not exceed 8 minutes.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The invention discloses a method for removing an over-aged film layer of aluminum alloy chemically oxidized. The method first makes the aged film layer loose and porous through electrochemical dissolution pretreatment. This step can effectively promote the penetration and reaction of the subsequent chemical corrosion liquid to the film layer, thereby significantly improving the efficiency of removing the film layer. At the same time, the uniformity of the electrochemical dissolution ensures the uniformity of the subsequent corrosion process, avoiding the problem of uneven corrosion rate in the traditional method. Due to the combined use of electrochemical dissolution and chemical corrosion, the film removal process can be more accurately controlled, avoiding the over-corrosion of parts caused by long-term corrosion. This not only protects the aluminum alloy substrate, but also ensures the dimensional accuracy and surface quality of the parts after the film layer is removed, meeting higher quality requirements. The method combines the dual effects of electrochemistry and chemical corrosion, and through reasonable step design and parameter setting, realizes the effective removal of the over-aged film layer of aluminum alloy chemically oxidized, while simplifying the complex steps in the traditional removal process, and improving the operability and stability of the overall process. Compared with traditional alkaline corrosion and pickling methods, the chemical corrosion solution (a mixed solution of sodium hydroxide solution, sodium carbonate solution and sodium fluoride solution) used in this method may have a lower environmental pollution risk, and the electrochemical dissolution process can effectively reduce the amount of chemical reagents used, which is in line with the current development trend of green manufacturing and energy conservation and emission reduction.

[0016] Furthermore, a sulfuric acid solution with a concentration of 200g / L-250g / L is used as the electrolyte, combined with a current density of 1.5A / dm²-2.5A / dm² and a voltage of 14V-20V at room temperature, and an electrochemical dissolution time of 2min-5min, which can quickly make the aged film layer loose and porous, providing a good pretreatment effect for subsequent chemical corrosion. This combination of electrochemical dissolution and chemical corrosion not only improves the removal efficiency, but also achieves precise control of the removal process, avoiding the problem of over-corrosion caused by long-term corrosion in traditional methods. The chemical corrosion solution is a mixture of 35g / L-45g / L sodium hydroxide solution, 20g / L-30g / L sodium carbonate solution and 20g / L-30g / L sodium fluoride solution. These components work synergistically to effectively accelerate the dissolution of the aged film layer. At the same time, a magnetic stirrer is used to keep the chemical corrosion solution uniform, ensuring the uniformity and consistency of the corrosion process. The temperature of chemical corrosion is controlled between 35℃-45℃, and the corrosion time is controlled between 60s-120s, which further optimizes the corrosion conditions and improves the removal efficiency and quality. The combination of electrochemical dissolution and chemical corrosion not only achieves the effective removal of the aged film layer, but also protects the aluminum alloy substrate to the maximum extent and avoids damage to the substrate caused by excessive corrosion. In addition, the light treatment step uses a mixture of 500ml / L-700ml / L nitric acid solution and 20ml / L-30ml / L sulfuric acid solution at room temperature for no more than 8 minutes, which further removes the residue and improves the finish and quality of the aluminum alloy surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 It is a flow chart of a method for removing an over-aged film layer of aluminum alloy chemical oxidation in the present invention; Figure 2 Schematic diagram of the structure of the electrochemical dissolution device according to an embodiment of the present invention.

[0019] Wherein: 1- cathode plate; 2- power supply; 3- electrolyte solution; 4- aluminum alloy sample with aged film layer. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0023] The present invention is further described in detail below in conjunction with the accompanying drawings: See also Figure 1 The embodiment of the present invention discloses a method for removing an aluminum alloy chemically oxidized over-aged film layer, comprising the following steps: Step 1: Use aluminum or titanium hangers to fasten the workpiece and hang the aluminum alloy sample with an aged film layer, so that the contact point is firm.

[0024] Step 2, ultrasonically degreasing the mounted aluminum alloy sample with the aged film layer; Immerse the mounted aluminum alloy sample with the aged film layer in a 3% to 5% metal cleaning agent aqueous solution at 30℃ to 40℃, turn on the ultrasonic cleaning machine, and clean it for 3min to 5min. After cleaning, use tap water to clean the metal cleaning agent aqueous solution on the sample.

[0025] Step 3, placing the aluminum alloy sample with an aged film layer as an anode in an electrolytic cell and adding an electrolyte, setting the electrochemical workstation parameters, and electrochemically dissolving the aluminum alloy sample to obtain a loose and porous aged film layer aluminum alloy sample; The electrolyte is a sulfuric acid solution with a concentration of 200g / L-250g / L; after the electrochemical dissolution is completed, the obtained loose porous aged film layer aluminum alloy sample is taken out and rinsed with deionized water. The parameters of the electrochemical workstation are that the current density is 1.5A / dm²-2.5A / dm² and the voltage is 14V-20V at room temperature; the electrochemical dissolution time is 2min-5min.

[0026] Step 4, placing the loose and porous aged film layer aluminum alloy sample in a chemical etching solution for chemical etching to obtain a corroded aluminum alloy sample; the chemical etching solution used is a mixed solution of sodium hydroxide solution, sodium carbonate solution and sodium fluoride solution; When performing the chemical etching, a magnetic stirrer is used to keep the chemical etching solution uniform. The chemical etching solution is a mixed solution of 35g / L-45g / L sodium hydroxide solution, 20g / L-30g / L sodium carbonate solution and 20g / L-30g / L sodium fluoride solution, the temperature is controlled between 35°C and 45°C, and the etching time is controlled between 60s and 120s.

[0027] Step 5, placing the corroded aluminum alloy sample into a polishing liquid, taking it out after polishing, rinsing and drying it, and completing the removal of the over-aged film layer of the aluminum alloy chemical oxidation.

[0028] The light emitting liquid is a mixed solution of 500ml / L-700ml / L nitric acid solution and 20ml / L-30ml / L sulfuric acid solution. The light emitting treatment is carried out at room temperature, and the treatment time does not exceed 8 minutes.

[0029] The invention discloses a method for removing an over-aged film layer of aluminum alloy chemically oxidized. The method first makes the aged film layer loose and porous through electrochemical dissolution pretreatment. This step can effectively promote the penetration and reaction of the subsequent chemical corrosion liquid to the film layer, thereby significantly improving the efficiency of removing the film layer. At the same time, the uniformity of the electrochemical dissolution ensures the uniformity of the subsequent corrosion process, avoiding the problem of uneven corrosion rate in the traditional method. Due to the combined use of electrochemical dissolution and chemical corrosion, the film removal process can be more accurately controlled, avoiding the over-corrosion of parts caused by long-term corrosion. This not only protects the aluminum alloy substrate, but also ensures the dimensional accuracy and surface quality of the parts after the film layer is removed, meeting higher quality requirements. The method combines the dual effects of electrochemistry and chemical corrosion, and through reasonable step design and parameter setting, realizes the effective removal of the over-aged film layer of aluminum alloy chemically oxidized, while simplifying the complex steps in the traditional removal process, and improving the operability and stability of the overall process. Compared with traditional alkaline corrosion and pickling methods, the chemical corrosion solution (a mixed solution of sodium hydroxide solution, sodium carbonate solution and sodium fluoride solution) used in this method has a lower environmental pollution risk, and the electrochemical dissolution process can effectively reduce the amount of chemical reagents used, which is in line with the current development trend of green manufacturing and energy conservation and emission reduction.

[0030] Example 1 Samples were selected: 2A12-H112 aluminum alloy material, which was chemically oxidized and then placed for a period of time, and then baked at 180°C for 2h to restore the aging process.

[0031] 1) Mounting: Use aluminum or titanium hangers to fasten and mount the workpiece, and the contact point is firm; 30℃2) Ultrasonic degreasing: immerse the mounted parts in a 3% metal cleaning agent aqueous solution, turn on the ultrasonic cleaning machine, and clean for 3 minutes; after cleaning, rinse off the ultrasonic solution with tap water; 3) Electrochemical dissolution: Prepare the solution according to the following ingredients: H2SO4 (analytical grade): 200g / L, select a suitable DC regulated power supply, select a lead plate as the cathode, hang the mounted workpiece on the anode, immerse the workpiece completely in the solution, and adjust the current density to 1.5A / dm 2 , the dissolution time is 2 minutes, and after the dissolution is completed, the workpiece is cleaned with tap water; 4) Chemical corrosion: Prepare the solution according to the chemical corrosion solution ingredients: NaOH (analytical grade): 35g / L; Na2CO3 (analytical grade): 20g / L; NaF (analytical grade): 20g / L, heat the solution to 35°C, immerse the workpiece after electrochemical dissolution in the chemical corrosion solution, and corrode for 100S. After the corrosion is completed, clean the workpiece with tap water; 5) Light emitting: Prepare the solution according to the following ingredients: HNO3 (analytical grade): 500ml / l; H2SO4 (analytical grade): 20ml / L, immerse the workpiece after chemical corrosion in the light emitting solution, light emitting for 2 minutes, and clean the workpiece with tap water after the light emitting is completed; 6) Perform subsequent surface treatment.

[0032] After removing the aged oxide film, the surface of the workpiece is uniform and delicate, without any roughness or excessive corrosion.

[0033] Example 2 Samples were selected: 2A12-T4 aluminum alloy material, which was chemically oxidized and then placed for a period of time, and then baked at 180°C for 2h to restore the aging process.

[0034] 1) Mounting: Use aluminum or titanium hangers to fasten and mount the workpiece, and the contact point is firm; 2) Ultrasonic degreasing: immerse the mounted parts in a 35°C, 4% metal cleaning agent aqueous solution, turn on the ultrasonic cleaning machine, and clean for 4 minutes; after cleaning, rinse off the ultrasonic solution with tap water; 3) Electrochemical dissolution: Prepare the solution according to the following ingredients: H2SO4 (analytical grade): 230g / L, select a suitable DC regulated power supply, select a lead plate as the cathode, hang the mounted workpiece on the anode, immerse the workpiece completely in the solution, and adjust the current density to 2.2A / dm 2 , the dissolution time is 4 minutes, and after the dissolution is completed, the workpiece is cleaned with tap water; 4) Chemical corrosion: Prepare the solution according to the chemical corrosion solution ingredients: NaOH (analytical grade): 40g / L; Na2CO3 (analytical grade): 25g / L; NaF (analytical grade): 25g / L, heat the solution to 40°C, immerse the workpiece after electrochemical dissolution in the chemical corrosion solution, and corrode for 100S. After the corrosion is completed, clean the workpiece with tap water; 5) Light emitting: Prepare the solution according to the ingredients of light emitting solution: HNO3 (analytical grade): 600ml / l; H2SO4 (analytical grade): 25ml / L, immerse the workpiece after chemical corrosion in the light emitting solution, light emitting for 5 minutes, and clean the workpiece with tap water after the light emitting is completed; 6) Perform subsequent surface treatment.

[0035] Example 3 Samples were selected: 5A06-H112 aluminum alloy material, which was chemically oxidized and then placed for a period of time, and then baked at 180°C for 2h to restore the aging process.

[0036] 1) Mounting: Use aluminum or titanium hangers to fasten and mount the workpiece, and the contact point is firm; 40℃2) Ultrasonic degreasing: immerse the mounted parts in a 5% metal cleaning agent aqueous solution, turn on the ultrasonic cleaning machine, and clean for 5 minutes; after cleaning, rinse off the ultrasonic solution with tap water; 3) Electrochemical dissolution: Prepare the solution according to the following ingredients: H2SO4 (analytical grade): 250g / L, select a suitable DC regulated power supply, select a lead plate as the cathode, hang the mounted workpiece on the anode, immerse the workpiece completely in the solution, and adjust the current density to 2.5A / dm 2 , the dissolution time is 5 min, and after the dissolution is completed, the workpiece is cleaned with tap water; 4) Chemical corrosion: Prepare the solution according to the chemical corrosion solution ingredients: NaOH (analytical grade): 45 g / L; Na2CO3 (analytical grade): 30 g / L; NaF (analytical grade): 30 g / L, heat the solution to 40°C, immerse the workpiece after electrochemical dissolution in the chemical corrosion solution, and corrode for 100 seconds. After the corrosion is completed, clean the workpiece with tap water; 5) Light emitting: Prepare the solution according to the ingredients of light emitting solution: HNO3 (analytical grade): 700ml / l; H2SO4 (analytical grade): 30ml / L, immerse the workpiece after chemical corrosion in the light emitting solution, light emitting for 8 minutes, and clean the workpiece with tap water after the light emitting is completed; 6) Perform subsequent surface treatment.

[0037] The following is a detailed introduction to the three aluminum alloy materials used in the three embodiments: (1) 2A12-H112 aluminum alloy material: Composition: 2A12-H112 aluminum plate is an alloy plate composed of aluminum, copper, magnesium, manganese and other elements. Among them, the aluminum content is not less than 90%, the copper content is between 1.2% and 2.0%, the magnesium content is between 2.0% and 3.0%, and the manganese content is between 0.3% and 0.9%.

[0038] performance: Strength and hardness: The tensile strength and yield strength of 2A12-H112 aluminum plate can reach 400MPa and 350MPa respectively, and the hardness is also high, reaching more than 110HB.

[0039] Plasticity: The aluminum plate has good plasticity, with an elongation of more than 12%, and is easy to process into various shapes and structures.

[0040] Corrosion resistance: The addition of copper element improves the corrosion resistance of aluminum plate, but the corrosion resistance is still not high. An aluminum layer can be added on the surface to improve the corrosion resistance.

[0041] Thermal conductivity: 2A12-H112 aluminum plate has high thermal conductivity, can quickly transfer heat, suitable for high temperature and high humidity environment.

[0042] Weldability: Spot welding has good weldability, but there is a tendency to form intergranular cracks when using gas welding and argon arc welding.

[0043] Application: Mainly used to make various high-load parts and components (but excluding stamping parts and forgings), such as aircraft skeleton parts, skins, bulkheads, wing ribs, wing beams, rivets and other parts working below 150°C.

[0044] (2) 2A12-T4 aluminum alloy material Composition: 2A12-T4 aluminum alloy material is mainly composed of aluminum, copper, magnesium, manganese and other elements. The copper content is relatively high, which can significantly improve the strength and hardness of the alloy; the addition of magnesium can improve the corrosion resistance of the alloy; the role of manganese is to improve the corrosion resistance and heat treatment strength of the alloy. At the same time, the addition of appropriate amounts of zinc, chromium and other elements can also improve the performance of the alloy.

[0045] performance: Mechanical properties: 2A12-T4 aluminum alloy material has excellent mechanical properties, with a tensile strength of up to 470MPa, a yield strength of 325MPa, an elongation of 10%, and a hardness of 120HB.

[0046] Heat resistance: It can still maintain good strength and heat resistance under high temperature conditions.

[0047] Machinability: It has good machinability and can be subjected to various forming processes such as forging, rolling, stretching, and extrusion.

[0048] Weldability: Good weld joint quality can be obtained by adopting appropriate welding process and method.

[0049] Application: Widely used in aerospace, automobile manufacturing, shipbuilding, electronic equipment and other fields. In the aerospace field, it is often used to manufacture aircraft structural parts, engine parts, spacecraft shells, etc.; in the automobile manufacturing field, it can be used to manufacture automobile bodies, wheels, engine parts, etc.; in the shipbuilding field, it can be used to manufacture hull structures, decks, bulkheads, etc.; in the electronic equipment field, it can be used to manufacture electronic shells, radiators, etc.

[0050] (3) 5A06-H112 aluminum alloy material Composition: 5A06-H112 aluminum rod belongs to Al-Mg series rust-proof aluminum alloy, the main alloying element is magnesium, the content is between 5.8% and 6.8%. In addition, it also contains a small amount of silicon, copper, zinc, manganese, titanium, beryllium, iron and other elements, the addition of these elements further improves the comprehensive performance of the alloy.

[0051] performance: Strength: It has high strength in the work-hardened state, especially excellent fatigue resistance.

[0052] Corrosion resistance: It exhibits good corrosion resistance in a variety of environments and is suitable for low-load parts working in liquid or gas media.

[0053] Weldability: Whether it is argon arc welding, gas welding or spot welding, the welded joint strength of 5A06-H112 aluminum bar is high, and the weld has good air tightness and plasticity.

[0054] Machinability: The machinability is poor in the annealed state, but acceptable in the semi-cold hardened state.

[0055] Application: Widely used in aerospace, weapons and ships, petrochemicals, transportation, electronic light industry and other fields. In the aerospace field, it is used to manufacture aircraft fuel tanks, oil pipes and other parts; in the weapons and ships field, it is used as an important structural material for ships and vessels; in the petrochemical industry, it is used to manufacture various corrosion-resistant pipes and containers.

[0056] The working principle of the present invention is as follows: Electrochemical anodic dissolution of the aged film layer loosens the aged film layer and produces pores. Combined with chemical corrosion to remove the loose film layer, the aged film layer can be removed while minimizing damage to the substrate.

[0057] Electrochemical dissolution treatment is based on the principle of electrochemistry. The aluminum alloy workpiece is used as the anode and placed in an electrolyte solution for power treatment. The aged chemical oxide film layer is loosened by electrolysis and electrolyte solution dissolution. Under the action of a strong external electric field, the aged oxide film layer is transformed into a porous oxide due to electrical breakdown and electrolyte solution dissolution. O2- migrates to the interface between the aluminum matrix and the oxide film, while Al3+ migrates to the interface between the oxide film and the solution. The migration of O2 fills the volume vacated by the consumption of the metal, allowing a new active layer to grow under the aged oxide film. As the reaction proceeds, the gaps in the aged film layer become larger and larger, making the aged oxide film loose and porous. After this step is completed, chemical corrosion is immediately carried out. The porous and loose film layer is easier to dissolve, and then light treatment is carried out to complete the removal of the aged film layer of the aluminum alloy chemical oxidation.

[0058] The oxide film generated by the electrochemical dissolution process is approximately 1-2μm, the aged film thickness is 0.125-1μm, and the total thickness is no more than 3μm. It will be corroded in the subsequent chemical corrosion process. The corroded film layer is thin and has little effect on the mechanical dimensions of the parts.

[0059] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for removing an over-aged film layer of an aluminum alloy chemically oxidized, characterized in that: The following steps are involved: The aluminum alloy sample with an aged film layer is used as an anode, placed in an electrolytic cell and an electrolyte is added, and the electrochemical workstation parameters are set to electrochemically dissolve the aluminum alloy sample to obtain a loose and porous aluminum alloy sample with an aged film layer; Putting the loose and porous aged film layer aluminum alloy sample into a chemical etching solution for chemical etching to obtain a corroded aluminum alloy sample; The corroded aluminum alloy sample is placed in a polishing liquid, and after the polishing treatment, it is taken out, rinsed and blown dry to complete the removal of the over-aged film layer of the aluminum alloy chemical oxidation.

2. The method for removing the over-aged film layer of aluminum alloy chemical oxidation according to claim 1 is characterized in that: Before the aluminum alloy sample is electrochemically dissolved, it is mounted and ultrasonically degreased; the mounting adopts aluminum or titanium hangers to fasten the workpiece.

3. The method for removing the over-aged film layer of aluminum alloy chemical oxidation according to claim 2 is characterized in that: The ultrasonic degreasing is specifically: Immerse the mounted aluminum alloy sample with an aged film layer in a 3% to 5% metal cleaning agent aqueous solution at 30°C to 40°C, turn on the ultrasonic cleaning machine, and clean it for 3 min to 5 min. After cleaning, use tap water to clean the metal cleaning agent aqueous solution on the sample.

4. The method for removing the over-aged film layer of aluminum alloy chemical oxidation according to claim 1 is characterized in that: The electrolyte is a sulfuric acid solution with a concentration of 200g / L-250g / L; after the electrochemical dissolution is completed, the obtained loose and porous aged film layer aluminum alloy sample is taken out and rinsed with deionized water.

5. The method for removing the over-aged film layer of aluminum alloy chemical oxidation according to claim 1 is characterized in that: The parameters of the electrochemical workstation are: current density of 1.5A / dm²-2.5A / dm², voltage of 14V-20V at room temperature; the time of the electrochemical dissolution is 2min-5min.

6. The method for removing the over-aged film layer of aluminum alloy chemical oxidation according to claim 1, characterized in that: The chemical etching solution is a mixed solution of 35g / L-45g / L sodium hydroxide solution, 20g / L-30g / L sodium carbonate solution and 20g / L-30g / L sodium fluoride solution.

7. The method for removing the over-aged film layer of aluminum alloy chemical oxidation according to claim 1 is characterized in that: When performing the chemical etching, a magnetic stirrer is used to keep the chemical etching solution uniform.

8. The method for removing the over-aged film layer of aluminum alloy chemical oxidation according to claim 1 is characterized in that: The temperature of the chemical etching is controlled between 35° C. and 45° C., and the etching time is controlled between 60s and 120s.

9. The method for removing the over-aged film layer of aluminum alloy chemical oxidation according to claim 1, characterized in that: The light emitting liquid is a mixed solution of 500ml / L-700ml / L nitric acid solution and 20ml / L-30ml / L sulfuric acid solution.

10. The method for removing the over-aged film layer of aluminum alloy chemical oxidation according to claim 1, characterized in that: The light extraction treatment is carried out at room temperature, and the treatment time does not exceed 8 minutes.

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