Aluminum part and preparation method thereof

Abstract

The invention relates to the technical field of vehicles, in particular to an aluminum part, a preparation method thereof and a vehicle. The preparation method of the aluminum part comprises the following steps that an aluminum-containing workpiece is subjected to anodic oxidation treatment, an aluminum oxide film is formed on the aluminum-containing workpiece, and the pore diameter of the aluminum oxide film ranges from 10 nm to 40 nm; performing primary hole sealing treatment on the aluminum oxide film by using a first hole sealing agent, wherein the first hole sealing agent comprises fluorozirconate; and performing secondary hole sealing treatment on the aluminum oxide film subjected to the primary hole sealing treatment by using a second hole sealing agent, wherein the second hole sealing agent comprises a silicon-based compound. By means of the method, the workpiece surface whitening risk can be reduced, and the requirement for acid and alkali resistance can be met while it is guaranteed that the workpiece appearance meets the customer requirement.

Description

Technical Field

[0001] This application relates to the field of vehicle technology, and in particular to aluminum parts and methods for their preparation. Background Technology

[0002] Aluminum and aluminum alloys are chosen for automotive window trim due to their unique physicochemical properties. However, automotive exterior parts are more susceptible to corrosion from the climate, thus requiring improved surface performance. Anodizing, a relatively mature surface treatment technology for aluminum alloy workpieces, typically involves forming an oxide film of appropriate thickness on the aluminum alloy surface under different process conditions, which can improve the surface properties of the aluminum alloy. However, the oxide film surface contains numerous micropores, making its corrosion resistance, weather resistance, and stain resistance insufficient for the use requirements of exterior parts. Therefore, it is necessary to seal the micropores on the oxide film surface. Common sealing methods include electrophoretic coating, boiling water sealing, and metal salt sealing. Among these, the macromolecular resin in electrophoretic coating cannot penetrate into the oxide film pores, only covering the oxide film surface; boiling water sealing has a poor sealing effect and its performance cannot meet practical needs; metal salt sealing mainly uses Ni-containing... 2+ and F - The chemicals used in this process pose significant risks to the environment and human health, necessitating strict regulations on their emissions. Consequently, the treatment costs for the resulting wastewater and liquid are high, and the sealing products are prone to a whitish appearance. Currently, Ni-free solutions have been developed. 2+ This environmentally friendly sealing agent eliminates the need for extensive resource-intensive treatment of sealing waste liquid and wastewater after use, achieving Ni-containing... 2+ The sealing agent has a good sealing effect, but it was found during use that it does not contain Ni. 2+ When environmentally friendly sealing agents are used on aluminum alloy workpieces, there is a problem that cannot simultaneously meet the requirements for appearance and acid and alkali resistance. Specifically, this manifests as: using Ni-free... 2+ After using environmentally friendly sealing agents, aluminum alloy workpieces are prone to developing a grayish-white appearance, which fails to meet customer aesthetic requirements. Prioritizing appearance would sacrifice acid and alkali resistance. Summary of the Invention

[0003] Based on this, the first aspect of this application provides a method for preparing an aluminum part, the technical solution of which is as follows:

[0004] A method for preparing an aluminum part includes the following steps:

[0005] Anodizing is performed on an aluminum-containing workpiece to form an aluminum oxide film on the workpiece, wherein the pore size of the aluminum oxide film is in the range of 10 nm to 40 nm.

[0006] The alumina film is subjected to a first sealing treatment using a first sealing agent, wherein the first sealing agent includes fluorozirconate;

[0007] The alumina film after the first sealing treatment is subjected to a second sealing treatment using a second sealing agent, which includes a silicon-based compound.

[0008] The second aspect of this application provides an aluminum component, which is manufactured by the preparation method described above.

[0009] Compared with traditional solutions, this application has the following advantages:

[0010] This application involves controlling the pore size of the alumina film during anodizing of aluminum workpieces. A first sealing agent, comprising fluorozirconate, is then used for initial sealing. Fluorozirconate ions hydrolyze within the pores of the alumina film, generating zirconium hydroxide, which fills the micropores, achieving the first stage of anodizing sealing. Since the pore size of the alumina film is controlled within the range of 10nm to 40nm during anodizing, the hydrolysis products of fluorozirconate ions can fill the pores, reducing accumulation at the pore openings and minimizing the risk of whitening and dusting on the workpiece surface. After the first stage of anodizing sealing, a second sealing agent, comprising a silicon-based compound, is used for a second stage of sealing, further sealing the pore openings of the alumina film and reducing the risk of whitening and dusting on the workpiece surface. Furthermore, the aluminum part obtained after the second sealing exhibits good acid and alkali resistance. In short, the method of this application can reduce the risk of whitening on the workpiece surface, ensuring that the workpiece appearance meets customer requirements while also satisfying corrosion resistance requirements. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of this application and to more completely understand this application and its beneficial effects, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a real-world image of the aluminum component in Comparative Example 1.

[0013] Figure 2 This is a real-world image of the aluminum component in Comparative Example 2.

[0014] Figure 3 This is a real-world image of the aluminum component in Comparative Example 3.

[0015] Figure 4 This is a real-world image of the aluminum component in Comparative Example 4.

[0016] Figure 5 This is a real-world view of the aluminum component from Example 1;

[0017] Figure 6 This is a real-world view of the aluminum component from Example 2;

[0018] Figure 7 This is a real-world view of the aluminum component in Example 3;

[0019] Figure 8 This is a schematic diagram for evaluating the corrosion resistance level of aluminum parts. Detailed Implementation

[0020] The present application will be further described in detail below with reference to specific embodiments. The present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0022] Unless otherwise stated or in case of contradiction, the terms or phrases used herein shall have the following meanings:

[0023] The first aspect of this application provides a method for preparing an aluminum part. In one embodiment, the method for preparing the aluminum part includes the following steps:

[0024] S10. The aluminum-containing workpiece is subjected to anodizing treatment to form an aluminum oxide film on the aluminum-containing workpiece, wherein the pore size of the aluminum oxide film is in the range of 10nm~40nm.

[0025] Optionally, before anodizing the aluminum-containing workpiece, the following steps are further included:

[0026] The aluminum-containing workpiece is subjected to pretreatment, which includes at least one of the following: degreasing, pickling, electrochemical polishing, and descaling.

[0027] In this embodiment, the aluminum-containing workpiece is subjected to degreasing, pickling, electrochemical polishing, and film removal and dust removal treatments in sequence. The aluminum-containing workpiece can be made of aluminum or an aluminum alloy.

[0028] The degreasing treatment of the aluminum-containing workpiece includes the following steps: immersing the aluminum-containing workpiece in a degreasing solution. Optionally, the degreasing solution includes a degreasing activator. The temperature of the degreasing solution is controlled at 50℃~65℃. The immersion time in the degreasing solution is 600s~700s. The degreasing treatment also includes the following step: removing the aluminum-containing workpiece and rinsing it thoroughly with pure water. The purpose of the degreasing treatment is to remove residual lubricating oil from the forming process and polishing slurry from the polishing process from the surface of the aluminum-containing workpiece, preventing them from affecting subsequent oxidation steps and causing problems such as color difference.

[0029] After degreasing, the workpiece needs to be thoroughly neutralized and rinsed with water. In this embodiment, after degreasing, the aluminum-containing workpiece undergoes pickling, including the following steps: immersing the aluminum-containing workpiece in a pickling solution. Optionally, the pickling solution includes sulfuric acid with a concentration of 150 g / L to 160 g / L. The immersion time in the pickling solution is 100 s to 1000 s. The pickling process also includes the following step: removing the aluminum-containing workpiece and rinsing it thoroughly with pure water. The purpose of the pickling process is to prevent excessive alkaline degreasing solution from being carried into the electrochemical polishing solution.

[0030] The aluminum-containing workpiece is subjected to electrochemical polishing after pickling, comprising the following steps: using the aluminum-containing workpiece as the anode, immersing the anode and cathode in an electrochemical polishing solution and applying an electric current. Optionally, the electrochemical polishing solution comprises sulfuric acid with a concentration of 600 g / L, phosphoric acid with a concentration of 450 g / L to 550 g / L, and aluminum ions with a concentration of 32 g / L to 40 g / L. The temperature of the electrochemical polishing solution is controlled at 56℃ to 60℃. The voltage applied is 20V to 30V. The energizing time is 600s to 900s. In this embodiment, the cathode can be a lead plate. After applying voltage to both the anode and cathode for electrochemical polishing, the aluminum-containing workpiece is immediately removed after power is cut off and rinsed twice with pure water. Electrochemical polishing is performed to improve the surface smoothness of the workpiece while removing some of the oil residue not completely removed in the previous degreasing process, preventing it from affecting the subsequent anodizing step.

[0031] The aluminum-containing workpiece undergoes a film removal and ash removal process after electrochemical polishing, comprising the following steps: immersing the aluminum-containing workpiece in an alkaline solution, then removing it and placing it in an acidic solution. Optionally, the alkaline solution includes sodium hydroxide with a concentration of 20 g / L to 30 g / L. The immersion time in the alkaline solution is 15 to 30 seconds. The acidic solution includes sulfuric acid with a concentration of 160 g / L to 200 g / L. The immersion time in the acidic solution is 60 to 90 seconds. After removing the aluminum-containing workpiece from the alkaline solution, it is rinsed twice with pure water, then placed in the acidic solution, and then rinsed twice with secondary pure water. Since a loose aluminum oxide film quickly forms on the surface of the aluminum-containing workpiece after electrochemical polishing when exposed to air, which affects the conductivity of the subsequent anodizing step, this film removal and ash removal step is to remove the aluminum oxide film from the surface of the aluminum alloy workpiece.

[0032] The pretreated aluminum-containing workpiece is then subjected to anodizing. In this embodiment, the pore size of the anodized alumina film is controlled within the range of 10 nm to 40 nm. For example, the pore size is controlled within the range of 20 nm to 40 nm, or within the range of 30 nm to 40 nm. Optionally, the aluminum-containing workpiece is used as the anode, and the anode and cathode are immersed in an electrolyte, with a voltage applied across the anode and cathode for anodizing. In this embodiment, the anode is the aluminum-containing workpiece, and the cathode is a lead plate.

[0033] Optionally, the electrolyte includes sulfuric acid and phosphoric acid, wherein the concentration of sulfuric acid is 160 g / L to 200 g / L, and the concentration of phosphoric acid is 80 g / L to 100 g / L. Anodizing uses an aluminum-containing workpiece as the anode, applies a constant DC voltage, and utilizes the different solubilities of aluminum in different electrolytes to form oxide films of different states on the surface. Among these, the oxide film formed using sulfuric acid as the anodizing electrolyte is transparent and colorless, has good corrosion resistance and wear resistance, and is easy to dye. However, its pore size is smaller than that formed using phosphoric acid as the electrolyte, which is not conducive to sealing and filling. In this embodiment, the pore size of the alumina film is controlled by adjusting the electrolyte ratio. Adding a small amount of phosphoric acid to the sulfuric acid electrolyte can reduce the growth rate of the alumina film and increase its porosity, thereby expanding the pore size of the alumina film to a certain extent.

[0034] Optimizing the anodizing process conditions can help widen the pore size of the alumina film. For example, appropriately increasing the oxidation voltage can widen the pore size of the alumina film. Optionally, the oxidation voltage for anodizing is 10V~20V. For example, oxidation voltages of 10V, 12V, 15V, 18V, and 20V. The oxidation time for anodizing is 500s~1500s. For example, oxidation times of 500s, 800s, 1000s, 1200s, and 1500s. The oxidation temperature for anodizing is 10℃~30℃. For example, oxidation temperatures of 10℃, 15℃, 20℃, 25℃, and 30℃.

[0035] The anodizing process also includes the following steps: immediately after power is cut off, remove the aluminum-containing workpiece, rinse it twice with secondary pure water, and then immerse it in secondary pure water.

[0036] After anodizing, aluminum-containing workpieces develop a porous alumina film on their surface. Optionally, the thickness of the alumina film is 5μm to 10μm. The gloss meets the requirement of 200~300 GU (60°). However, due to its porous structure, SO4 can easily remain in the pores of the alumina film during anodizing. 2+ Mg 2+ Si 2+Alumina films containing impurities such as ions and without pore sealing easily adsorb dirt, therefore, deep cleaning of the alumina film is necessary. Optionally, ultrasonic cleaning can be performed on the alumina film. The anodized aluminum-containing workpiece is immersed in secondary pure water and ultrasonically cleaned at a power of 0.1kW~1kW, a frequency of 20kHz~40kHz, and a time of 10~20 minutes. After ultrasonic cleaning, it is rinsed with secondary pure water for later use. Compared to traditional immersion cleaning, ultrasonic cleaning has a better cleaning effect on the pores of the alumina film, which is conducive to the formation of an alkaline environment within the pores, facilitating the filling of the sealing agent.

[0037] S20. The alumina film is sealed with a first sealing agent, wherein the first sealing agent includes fluorozirconate.

[0038] In this embodiment, an aluminum-containing workpiece with an alumina film on its surface is immersed in a cold sealing tank filled with a first sealing liquid, which includes a first sealing agent and a tank preparation solvent. The tank preparation solvent is pure water. The concentration of the first sealing agent in the first sealing liquid is 10 g / L to 100 g / L. Optionally, the first sealing agent includes fluorozirconate, and the mass percentage of the fluorozirconate in the first sealing agent is 0.1% to 20%. For example, the mass percentages are 0.1%, 1%, 5%, 10%, 15%, and 20%. By controlling the concentration of fluorozirconate on the surface of the alumina film, the reaction rate can be controlled, which helps to reduce the risk of whitening and dusting on the workpiece surface. Optionally, the fluorozirconate includes at least one of ammonium fluorozirconate, potassium fluorozirconate, sodium fluorozirconate, potassium-sodium composite fluorozirconate, potassium hydrogen fluorozirconate, lithium fluorozirconate, and cerium fluorozirconate. During the primary sealing process, fluoride ions react with the alumina film, and the reaction equation is: Al₂O₃ + 12F⁻. - +H₂O=2AlF₆ 3- +OH - Subsequently, zirconate ions hydrolyze within the pores of the alumina membrane to generate zirconium hydroxide, as shown in the reaction equation: ZrF6 2- +4H₂O=Zr(OH)₄+6F - +4H + Zr(OH)4 acts as a filler for the micropores, achieving the first stage of oxidation sealing. At this time, because the pore size of the alumina film is controlled within the range of 10nm~40nm during the anodizing process, the hydrolysis products of fluorozirconate ions can fill the pores of the alumina film, reducing the accumulation at the pore openings and thus reducing the risk of whitening and dusting on the workpiece surface.

[0039] Optionally, the first sealing agent further includes 0.1% to 20% acetic acid by mass as a pH inhibitor to adjust the solution pH. Optionally, the first sealing agent does not contain Ni. 2+ It is a nickel-free sealing agent, which helps reduce environmental pollution. Optionally, the first sealing agent also includes a solvent, which can be water.

[0040] During a single-stage sealing process, appropriately extending the sealing time helps zirconium hydroxide fill the entire oxide film pores. However, excessively long sealing times can affect production cycle time and make it difficult to match actual production requirements. Furthermore, appropriately increasing the sealing temperature can improve sealing efficiency and shorten sealing time; however, excessively high sealing temperatures (>40℃) can cause an excessively rapid reaction rate, making the sealing process difficult to control and hindering the control of whitening on the workpiece surface. Optionally, the sealing temperature for a single-stage sealing process is 20℃~35℃. For example, the sealing temperatures for a single-stage sealing process are 20℃, 25℃, 30℃, and 35℃. The single-stage sealing process is performed at room temperature, and optionally, the sealing time for a single-stage sealing process is 500s~2000s. For example, the sealing times for a single-stage sealing process are 500s, 1000s, 1500s, and 2000s.

[0041] Optionally, the pressure drop of the circulating pump during the primary sealing process is 0.05MPa ~ 0.15MPa. The primary sealing process also includes the following steps: immediately cleaning the aluminum-containing workpiece with secondary pure water after it is removed.

[0042] S30. The alumina film after the first sealing treatment is subjected to a second sealing treatment using a second sealing agent, wherein the second sealing agent includes a silicon-based compound.

[0043] In this embodiment, the aluminum-containing workpiece after the first sealing treatment is immersed in a heat-sealing tank filled with a second sealing liquid. The second sealing liquid includes a second sealing agent and a tank preparation solvent. The tank preparation solvent is pure water. The concentration of the second sealing agent in the second sealing liquid is 10 g / L to 100 g / L. Optionally, the silicon-based compound has a mass percentage of 0.1% to 20% in the second sealing agent. For example, the mass percentage is 0.1%, 1%, 5%, 10%, 15%, or 20%. Optionally, the silicon-based compound includes at least one of silicates and organosilanes. Optionally, the silicate includes sodium silicate. The organosilane includes at least one of epoxy silane compounds, methyl silane compounds, and phenyl silane compounds.

[0044] Optionally, the second sealing agent further includes 0.1% to 20% acetic acid by mass as a pH inhibitor to adjust the solution pH. Optionally, the second sealing agent does not contain Ni. 2+ This is a nickel-free sealing agent, which helps reduce environmental pollution. Optionally, the second sealing agent also includes a solvent, which can be water.

[0045] Optionally, the sealing temperature for the secondary sealing process is 95℃~100℃, such as 90℃, 95℃, 98℃, or 100℃. Performing the secondary sealing process at a high temperature is beneficial for sealing the pores of the alumina film. Optionally, the sealing time for the secondary sealing process is 500s~2000s, such as 500s, 1000s, 1500s, or 2000s.

[0046] After the secondary sealing process is completed, the aluminum-containing workpiece is taken out and immediately rinsed with secondary pure water, and then dried in an oven at 50℃~100℃.

[0047] In this embodiment, during the anodizing process of aluminum-containing workpieces, the pore size of the alumina film is controlled. Then, a first sealing agent comprising fluorozirconate is used for a primary sealing treatment. Fluorozirconate ions hydrolyze within the pores of the alumina film to generate zirconium hydroxide, which fills the micropores, achieving the first stage of anodizing sealing. Since the pore size of the alumina film is controlled within the range of 10nm to 40nm during the anodizing process, the hydrolysis products of the fluorozirconate ions can fill the pores, reducing accumulation at the pore openings and thus minimizing the risk of whitening and dusting on the workpiece surface. After the first stage of anodizing sealing, a second sealing agent comprising a silicon-based compound is used for a secondary sealing treatment to seal the pore openings of the alumina film, further reducing the risk of whitening and dusting on the workpiece surface. Furthermore, after the second sealing treatment, the resulting aluminum part exhibits excellent corrosion resistance. In short, the method of this application can reduce the risk of whitening on the workpiece surface, ensuring that the workpiece appearance meets customer requirements while also satisfying corrosion resistance requirements.

[0048] While traditional nickel salt sealing agents can achieve a salt spray resistance of ≥240h, it cannot exceed 360h, and the wastewater and waste liquid treatment is cumbersome and costly. The first and second sealing agents in the above embodiments can both be nickel-free. 2+ This reduces the cost and production efficiency requirements of factory wastewater and waste liquid discharge treatment, has a salt spray resistance of ≥360h, and can overcome the problem of graying and whitening on the workpiece surface caused by traditional nickel-free sealing agents, reducing the risk of graying and whitening on the aluminum parts surface, ensuring appearance yield, and can also take into account corrosion resistance. The resulting aluminum parts not only have good corrosion resistance, but also good salt spray corrosion resistance, meeting the performance requirements of automotive window exterior parts.

[0049] A second aspect of this application provides an aluminum component, which in one embodiment is prepared by the preparation method described above.

[0050] The following description is further illustrated with specific embodiments and comparative examples. Unless otherwise specified, the raw materials involved in the following specific embodiments and comparative examples are all commercially available. Unless otherwise specified, the instruments used are all commercially available. Unless otherwise specified, the processes involved are conventionally selected by those skilled in the art.

[0051] Comparative Example 1

[0052] This comparative example provides an aluminum part and its preparation method, the steps of which are as follows:

[0053] The 6063 aluminum alloy workpieces were subjected to degreasing, pickling, electrochemical polishing, film removal and ash removal, anodizing, ultrasonic cleaning, primary sealing and secondary sealing in sequence.

[0054] The anodizing process includes the following steps: A 6063 aluminum alloy workpiece is used as the anode and immersed in an anodizing bath. The anodizing bath consists of sulfuric acid (160 g / L) and phosphoric acid (90 g / L). A constant 15 V DC voltage is applied at 18°C ​​for 720 s, during which an aluminum oxide film forms on the surface of the aluminum alloy workpiece. Immediately after power is cut off, the workpiece is removed, rinsed twice with distilled water, and then immersed in distilled water again. The pore size of the aluminum oxide film on the surface of the 6063 aluminum alloy workpiece is measured using a scanning electron microscope; the pore size is ~23 nm. The main parameters and pore sizes of the anodizing process are summarized in Table 1.

[0055] The primary sealing process includes the following steps: Immersing a 6063 aluminum alloy workpiece with an alumina film on its surface into a traditional nickel-containing cold sealing tank. This tank is filled with a first sealing solution, prepared by mixing a first sealing agent and water to achieve a concentration of 50 g / L. The first sealing agent comprises 10 wt% nickel fluoride, 10 wt% acetic acid, and 80 wt% water. After immersion in the first sealing solution at 20°C for 900 seconds, the workpiece is immediately removed and rinsed with secondary pure water. The main parameters of the primary sealing process are summarized in Table 1.

[0056] The secondary sealing process includes the following steps: The 6063 aluminum alloy workpiece, after the initial sealing process, is immersed in a traditional nickel-containing heat-sealing tank filled with a second sealing liquid. The second sealing liquid is prepared by mixing a second sealing agent and water to achieve a concentration of 50 g / L. The second sealing agent comprises 10 wt% nickel acetate, 10 wt% acetic acid, and 80 wt% water. After immersion in the second sealing liquid at 98°C for 1200 seconds, the workpiece is immediately removed and rinsed with secondary pure water to obtain the aluminum part.

[0057] Comparative Examples 2 to 4

[0058] Comparative Examples 2 to 4 provide an aluminum part and its preparation method, which are basically the same as Comparative Example 1. The main differences are shown in Table 1.

[0059] Table 1

[0060]

[0061] Where ~ indicates a fluctuation of 1 nm above or below the given value.

[0062] The aluminum parts obtained from Comparative Examples 1 to 4 were subjected to visual inspection. See the attached images for the actual appearance. Figures 1-4 In Comparative Example 1, the aluminum part exhibited a severely whitish appearance (level 5) after the secondary sealing treatment. Comparative Examples 2-4 showed improved appearances after the secondary sealing treatment, exhibiting only a slight whitish appearance (levels 3-3.5). This indicates that after traditional nickel-containing first and second sealing treatments, the aluminum part inevitably exhibits an abnormal whitish appearance. Increasing the oxidation voltage, the first sealing time, and the first sealing temperature can improve the whitish appearance problem, but cannot completely solve it. Increasing the first sealing temperature shows the best improvement effect.

[0063] Examples 1 to 3, Comparative Example 3

[0064] Examples 1 to 3 provide an aluminum part and its preparation method, which are basically the same as Comparative Example 3. The main differences are shown in Table 2.

[0065] Table 2

[0066]

[0067] Where ~ indicates a fluctuation of 1 nm above or below the given value.

[0068] The aluminum parts obtained in Examples 1 to 3 and Comparative Example 3 were subjected to performance tests. The test items are as follows:

[0069] Project 1: See the actual appearance of the aluminum parts in each embodiment. Figures 5-7 And Table 3.

[0070] Project 2: Test the thickness of the aluminum oxide film on the surface of aluminum parts. The results are shown in Table 3.

[0071] Project 3: Alkali Resistance Test. Immerse the sample in a sodium hydroxide solution with a pH of 13.0 for 10 minutes, remove, wash, and air dry naturally before surface rating. The rating criteria are as follows: Figure 8 The results are shown in Table 3.

[0072] Project 4: Acid and Alkali Resistance Composite Test. First, immerse the sample in a test solution with a pH of 1.6 for 10 minutes, then remove and rinse. Next, immerse it in a test solution with a pH of 13.0 for 10 minutes, remove, rinse, and allow to air dry. Then, perform surface rating according to the rating criteria. Figure 8 The results are shown in Table 3.

[0073] Project 5: Refer to ISO 9227 Copper Salt Accelerated Acetic Acid (CASS) test. Observe the surface after 8 hours. The results are shown in Table 3.

[0074] Project 6: Refer to ISO 9227 Neutral Salt Spray (NSS) test. Observe the surface after 360 hours. The results are shown in Table 3.

[0075] Table 3

[0076]

[0077] Combination Figures 5 to 7 As can be seen, compared with Comparative Example 3, the aluminum parts of Examples 1-3 do not have the problem of surface dusting or whitening, and their performance meets the requirements by passing the alkali resistance 13.0 test, acid and alkali resistance 1.6+13.0 test, CASS-8H and NSS-360H test. The nickel-free sealing technology used in this patent application effectively solves the problem of poor appearance of workpieces produced by traditional nickel-containing sealing agents, achieving both appearance and surface performance while reducing environmental pollution.

[0078] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0079] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for preparing an aluminum part, characterized in that, Includes the following steps: Anodizing is performed on an aluminum-containing workpiece to form an aluminum oxide film on the workpiece, wherein the pore size of the aluminum oxide film is in the range of 10 nm to 40 nm. The alumina film is subjected to a first sealing treatment using a first sealing agent, wherein the first sealing agent includes fluorozirconate; The alumina film after the first sealing treatment is subjected to a second sealing treatment using a second sealing agent, which includes a silicon-based compound.

2. The method for preparing aluminum parts according to claim 1, characterized in that, The primary sealing process meets the following process conditions: (1) The sealing temperature is 20℃~35℃; (2) The sealing time is 500s~2000s.

3. The method for preparing aluminum parts according to claim 1, characterized in that, Includes the following features: (1) The fluorozirconate includes at least one of ammonium fluorozirconate, potassium fluorozirconate, sodium fluorozirconate, potassium sodium composite fluorozirconate, potassium hydrogen fluorozirconate, lithium fluorozirconate and cerium fluorozirconate; (2) The mass percentage of the fluorozirconate in the first sealing agent is 0.1% to 20%.

4. The method for preparing aluminum parts according to claim 1, characterized in that, Includes the following features: (1) The first sealing agent further includes acetic acid at a mass percentage of 0.1% to 20%; (2) During the first sealing process, the aluminum-containing workpiece with the alumina film on the surface is immersed in the first sealing liquid. The first sealing liquid includes a first sealing agent and a mixing solvent. The concentration of the first sealing agent in the first sealing liquid is 10g / L~100g / L.

5. The method for preparing aluminum parts according to claim 1, characterized in that, The silicon-based compound includes at least one of silicates and organosilanes.

6. The method for preparing aluminum parts according to claim 1, characterized in that, The secondary sealing process meets the following process conditions: (1) The sealing temperature is 90℃~100℃; (2) The sealing time is 500s~2000s.

7. The method for preparing aluminum parts according to claim 1, characterized in that, Includes the following features: (1) The silicon-based compound accounts for 0.1% to 20% of the mass percentage in the second sealing agent; (2) The second sealing agent also includes acetic acid at a mass percentage of 0.1% to 20%; (3) During the secondary sealing process, the aluminum-containing workpiece after the primary sealing process is immersed in the second sealing liquid. The second sealing liquid includes a second sealing agent and a tank preparation solvent. The concentration of the second sealing agent in the second sealing liquid is 10g / L~100g / L.

8. The method for preparing an aluminum part according to any one of claims 1 to 7, characterized in that, The anodizing process meets the following process conditions: (1) The oxidation voltage for anodizing is 10V~20V; (2) The oxidation time for anodizing is 500s~1500s; (3) The oxidation temperature of anodizing is 10℃~30℃.

9. The method for preparing the aluminum part according to any one of claims 1 to 7, characterized in that, The electrolyte for anodic oxidation includes sulfuric acid and phosphoric acid, wherein the concentration of sulfuric acid is 160 g / L to 200 g / L and the concentration of phosphoric acid is 80 g / L to 100 g / L.

10. An aluminum component, characterized in that, It is prepared by any one of the preparation methods according to claims 1 to 9.

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