Anodic oxidation dyeing method for 2A12 aluminum alloy

Abstract

The invention relates to the technical field of 2A12 aluminum alloy surface treatment, in particular to a 2A12 aluminum alloy anodic oxidation dyeing method which comprises the steps that S1, an oxidation film dyeing performance index prediction value is obtained; s2, an oxidation film dyeing performance index threshold value range is set, and then a 2A12 aluminum alloy workpiece to be dyed is subjected to pretreatment and anodic oxidation treatment in sequence; s3, the 2A12 aluminum alloy workpiece is washed with water to remove residual acid; s4, the 2A12 aluminum alloy workpiece with the residual acid removed is put into a coloring agent BK to be dyed; s5, the workpiece is put into a nickel acetate sealing agent WBX for hole sealing; s6, baking after blow-drying, and then inspecting the appearance of the 2A12 aluminum alloy workpiece; by introducing the oxidation film dyeing performance prediction model, anodic oxidation parameters can be scientifically predicted and dynamically adjusted, and ideal dyeing effect can be obtained in each treatment, so that products which are uniform in dyeing, good in durability, high in production efficiency and stable in quality are obtained, and the reliability and adaptability of the process are remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of 2A12 aluminum alloy surface treatment, in particular to a method for anodizing and dyeing the 2A12 aluminum alloy. Background Art

[0002] 2A12 aluminum alloy is widely used in aerospace, automobile manufacturing, and architectural decoration due to its excellent mechanical properties and corrosion resistance. However, in order to further improve its aesthetics and functionality, anodizing dyeing process is particularly important. The surface of untreated aluminum alloy is monotonous and unattractive. Dyeing can give the workpiece a variety of colors, significantly improving the aesthetics of the product and meeting the diverse market needs.

[0003] When dyeing, traditional processes rely on historical data and the experience of operators to set process parameters. They lack scientific basis and systematic optimization methods, leading to problems such as uneven dyeing, poor durability, low production efficiency, poor adaptability, and waste of resources. Specifically, due to factors such as uneven oxide film thickness and irregular porosity distribution, the color after dyeing varies in depth, affecting the appearance quality; when the oxide film structure is not dense enough or has defects, the dyed workpiece is prone to fading and discoloration, reducing the service life; and repeated trials to adjust parameters not only increase the consumption of raw materials and energy, but also extend the production cycle and increase costs. In addition, when environmental conditions such as temperature and humidity change, the process parameters cannot be adjusted in time, resulting in fluctuations in product quality and increased scrap rate. These problems not only affect the appearance quality and durability of the product, but also limit the competitiveness and market expansion capabilities of enterprises. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for anodizing and dyeing of 2A12 aluminum alloy. By introducing an oxide film dyeing performance prediction model, the anodizing parameters can be scientifically predicted and dynamically adjusted to ensure that an ideal dyeing effect can be obtained each time the treatment is carried out, thereby achieving products with uniform dyeing, good durability, high production efficiency and stable quality, and significantly improving the reliability and adaptability of the process.

[0005] A method for anodizing and dyeing a 2A12 aluminum alloy of the present invention comprises the following steps:

[0006] S1, measuring the copper content of the 2A12 aluminum alloy workpiece to be dyed and the current ambient temperature and humidity, inputting the copper content, the current ambient temperature and humidity and the anodizing parameters into a pre-constructed oxide film dyeing performance prediction model to obtain an oxide film dyeing performance index prediction value;

[0007] The quality of the oxide film directly affects the penetration and distribution of the dye. A uniform, dense and consistent oxide film can ensure that the dye penetrates the film layer evenly, avoiding the problem of different shades of color. If the oxide film is uneven in thickness or has defects, a mottled and uneven color effect may appear after dyeing, seriously affecting the appearance quality of the product.

[0008] High-quality oxide film can significantly reduce the scrap rate caused by dyeing failure. Through the predicted value of oxide film dyeing performance index, the quality of oxide film can be scientifically evaluated before processing, and the anodizing parameters can be dynamically adjusted according to the predicted results. This method avoids the uncertainty caused by reliance on experience and trial and error in traditional processes, ensuring that ideal dyeing effects can be obtained every time. Accurate parameter adjustment not only improves the adaptability of the process, but also reduces quality fluctuations caused by environmental changes or different initial conditions.

[0009] During the oxidation process, copper reacts with aluminum in a complex chemical reaction, which causes the growth rate and final thickness of the oxide film to change. A higher copper content may slow down the formation of the oxide film, making it thinner and less dense.

[0010] An increase in ambient temperature usually accelerates the growth rate of the oxide film, but too high a temperature may cause the oxide film to form too quickly and become uneven. The appropriate temperature range can ensure that the oxide film thickness is moderate and uniform. In a high humidity environment, the evaporation rate of water in the electrolyte slows down, which may affect the concentration and conductivity of the electrolyte, and thus affect the formation of the oxide film.

[0011] Anodizing parameters include:

[0012] Sulfuric acid concentration: Sulfuric acid is used as an electrolyte, and its concentration directly affects the growth rate and thickness of the oxide film. A higher sulfuric acid concentration can accelerate the formation of the oxide film, but too high a concentration may cause the film layer to be uneven or loose;

[0013] Aluminum ion concentration: Aluminum ions will gradually accumulate during the electrolysis process. Too high a concentration may affect the conductivity and reaction rate of the electrolyte, resulting in a decrease in the quality of the oxide film.

[0014] Electrolyte temperature: The electrolyte temperature has a significant effect on the growth rate and structure of the oxide film; a suitable low temperature can slow down the oxidation rate and make the oxide film more dense and uniform;

[0015] Voltage: directly affects the growth rate and thickness of the oxide film. Higher voltage can accelerate the formation of the oxide film, but too high voltage may cause the film to be too thick or cracks to appear.

[0016] Current density: determines the growth rate of the oxide film. A higher current density can accelerate the formation of the oxide film, but too high a current density may cause an uneven film layer or even burn the workpiece.

[0017] Electrolysis time: The longer the electrolysis time, the thicker the oxide film. However, too long a time may cause the oxide film to be too thick, affecting the subsequent dyeing effect.

[0018] Step S1 determines the copper content and current ambient temperature and humidity of the 2A12 aluminum alloy workpiece, and inputs the results into a pre-built oxide film dyeing performance prediction model in combination with the anodizing parameters to obtain an oxide film dyeing performance index prediction value. This process can scientifically predict and optimize process parameters, ensuring that an ideal oxide film can be obtained each time anodizing treatment is performed, laying a good foundation for subsequent dyeing quality.

[0019] S2, setting a threshold range of the oxide film staining performance index, and comparing the oxide film staining performance index prediction value with the oxide film staining performance index threshold range;

[0020] If the oxide film dyeing performance index prediction value is outside the oxide film dyeing performance index threshold range, the anodizing parameters are adjusted and the oxide film dyeing performance index prediction value is obtained again until the oxide film dyeing performance index prediction value is within the oxide film dyeing performance index threshold range, and then the 2A12 aluminum alloy workpiece to be dyed is pretreated and anodized in sequence;

[0021] When the predicted value is not within the threshold range, the anodizing parameters (such as voltage, current density, temperature, time, etc.) can be adjusted in time to ensure that the quality of the final oxide film meets the requirements. This method not only improves the adaptability of the process, but also reduces the quality fluctuations caused by environmental changes or different initial conditions. At the same time, the predicted value of the oxide film dyeing performance index is compared with the threshold range, which reduces the time and resource consumption of repeated experiments.

[0022] S3. After anodizing, the 2A12 aluminum alloy workpiece is washed with water to remove residual acid;

[0023] Water washing can effectively remove residual electrolyte (such as sulfuric acid) and other reaction products attached to the surface of the oxide film, preventing these substances from continuing to react chemically with the workpiece in subsequent processes and affecting the quality and dyeing effect of the oxide film. The clean surface helps the subsequent dyeing and sealing processes to proceed smoothly, ensuring that the dye and sealant can be evenly attached to the oxide film, thereby obtaining ideal dyeing effects and protective performance.

[0024] S4, putting the 2A12 aluminum alloy workpiece after the residual acid is removed into the dye BK for dyeing, and after dyeing, washing with water to remove the dye on the surface of the 2A12 aluminum alloy workpiece;

[0025] Through dyeing, the workpiece can be given the desired color, significantly improving its appearance quality and visual appeal to meet the needs of different application scenarios and customers. The dye can evenly penetrate into the micropores of the oxide film and firmly bond with the oxide film to ensure color consistency and durability, avoiding color unevenness or fading. Washing after dyeing can effectively remove the excess dye that has not been absorbed on the surface of the workpiece, preventing these excess substances from affecting the quality of the workpiece and the stability of the dyeing effect in subsequent processes.

[0026] S5, placing the 2A12 aluminum alloy workpiece into nickel acetate sealant WBX for hole sealing, and washing with water after the hole sealing is completed;

[0027] The sealant can fill and seal the micropores in the oxide film, preventing moisture, oxygen and other corrosive media in the external environment from penetrating into the substrate, significantly improving the corrosion resistance and protective performance of the oxide film; after sealing, washing with water can effectively remove the excess sealant that has not been absorbed on the surface of the workpiece, ensuring the surface is clean and does not affect subsequent processing or use;

[0028] S6. Bake after drying, and then inspect the appearance of the 2A12 aluminum alloy workpiece;

[0029] Blow-drying and baking can completely remove moisture and residual moisture on the surface of the workpiece, ensuring that the sealer and dye layer are completely dried and cured, enhancing their stability and durability.

[0030] As a preferred embodiment of the present invention, the pre-processing method in step S2 includes:

[0031] S21. Remove surface defects of 2A12 aluminum alloy workpiece by physical polishing and grinding;

[0032] S22, then remove the oil stains on the surface of the 2A12 aluminum alloy workpiece;

[0033] S23, after removing oil stains and defects, chemically polishing the 2A12 aluminum alloy workpiece;

[0034] The pretreatment step ensures the high quality and flatness of the workpiece surface by eliminating surface defects, removing oil stains and chemical polishing, laying a solid foundation for the successful implementation of subsequent anodizing and dyeing processes.

[0035] As a preferred embodiment of the present invention, the method of physical polishing and grinding comprises:

[0036] Use 400# flocking sandpaper to grind the workpiece to remove appearance defects, and then use a scouring pad to polish the 2A12 aluminum alloy workpiece as a whole until the appearance is consistent, with a finish of ≤0.8um;

[0037] 400# flocking sandpaper has a moderate particle size, which can remove surface defects without excessively damaging the workpiece surface and retain sufficient material thickness. Compared with coarser or finer sandpaper, 400# flocking sandpaper can achieve ideal grinding effect in a shorter time, improving production efficiency. After being polished with flocking sandpaper, the surface is basically flat, but there may still be tiny irregularities. Further polishing with a scouring pad can refine these tiny defects and make the entire surface reach a highly consistent finish.

[0038] The oxide film formed during the anodizing process contains a large number of micropores, which are crucial for the penetration of dyes. Surface finish ≤ 0.8 μm can ensure a more uniform distribution of micropores in the oxide film and avoid local uneven thickness caused by surface roughness.

[0039] The method for removing oil stains from the surface of 2A12 aluminum alloy workpiece includes:

[0040] Immerse the 2A12 aluminum alloy workpiece in a degreasing agent with a temperature of 50-60°C and a concentration of 15% w / w, and use ultrasonic waves; remove the workpiece and wash it with water to remove the surface oil and degreasing agent;

[0041] The degreasing agent can be sodium hydroxide solution, sodium carbonate solution, etc. 50-60℃ will not cause thermal damage to the aluminum alloy material, ensuring that the physical properties of the workpiece are not affected. At the same time, 50-60℃ can accelerate the dissolution rate of the degreasing agent on grease and oil, and improve the decontamination efficiency;

[0042] Water washing can effectively remove the residual degreasing agent and dissolved oil on the surface of the workpiece to ensure that the surface is completely clean. This step prevents the degreasing agent residue from having adverse effects on the workpiece in subsequent processes (such as anodizing and dyeing);

[0043] Chemical polishing methods include:

[0044] Immerse the 2A12 aluminum alloy workpiece in a chemical polishing liquid SK (Quanshengxing: 80% phosphoric acid, 20% additive) at a temperature of 90-100°C, and wash with water after treatment; then put it into a neutralizer CH (Quanshengxing: 60% sodium persulfate, 40% corrosion inhibitor) at room temperature and a concentration of 10-20% w / w to remove the generated ash;

[0045] Chemical polishing can further remove minor defects that physical polishing cannot completely eliminate, such as tiny scratches and pits, making the workpiece surface smoother and flatter. The smooth surface helps the dye to evenly penetrate into the oxide film, ensuring the consistency and durability of the color and avoiding the phenomenon of uneven color depth or fading.

[0046] The chemical polishing liquid at 90-100℃ is highly active and can evenly treat the entire workpiece surface in a short time, avoiding the problem of insufficient or excessive local treatment, which makes the surface unevenness and the oxide layer be dissolved and removed faster, thus improving the polishing efficiency;

[0047] Room temperature treatment reduces energy consumption, and the neutralizer CH at a concentration of 10-20% w / w can effectively neutralize acid residues without causing excessive treatment or waste, thus balancing the effect and cost and reducing waste liquid discharge.

[0048] As a preferred embodiment of the present invention, the method of anodizing in step S2 comprises:

[0049] S2a, equipped with the following electrolyte: sulfuric acid concentration: 180-220g / L, aluminum ion concentration <10g / L; and the electrolyte temperature is controlled at 8-10℃;

[0050] Sulfuric acid is the main electrolyte, and its concentration directly affects the growth rate and thickness of the oxide film. The concentration range of 180-220g / L can ensure that the oxide film is uniform and dense while providing sufficient conductivity and reaction activity. Aluminum ions will gradually accumulate during the anodizing process. Too high a concentration will affect the conductivity and reaction rate of the electrolyte, resulting in a decrease in the quality of the oxide film. Controlling the aluminum ion concentration below 10g / L can ensure the stability of the electrolyte composition and maintain ideal oxidation conditions.

[0051] Controlling the electrolyte temperature at 8-10°C can slow down the oxidation rate and make the oxide film denser and more uniform;

[0052] S2b, the voltage is set to climb for 5 minutes, and the final voltage is 18V;

[0053] The 5-minute ramp-up can effectively prevent the oxide film from forming too quickly due to a sudden increase in voltage. If the voltage reaches a high value instantly, the oxide film may grow too quickly locally, resulting in an uneven or loose structure, or even cracks.

[0054] The 18V voltage can ensure that the oxide film is formed quickly and evenly without causing film defects or material damage due to excessive voltage, thus achieving the best balance between efficiency and quality.

[0055] S2c, place the pretreated 2A12 aluminum alloy workpiece into the electrolyte, and control the current density at 1-3A / dm 2 , the electrolysis time is 50-70min; the thickness of the obtained oxide film is 10-15um;

[0056] 1-3A / dm 2The current density can ensure the oxide film to form quickly and be uniform and dense. Too high a current density may cause local overheating or uneven oxide film, while too low a current density will slow down the oxide film formation and affect production efficiency.

[0057] The oxide film thickness of 10-15μm is not only sufficient to provide good corrosion resistance, but also has high hardness and wear resistance. It is particularly suitable for applications that need to withstand frequent friction or wear. The oxide film in this thickness range can provide sufficient microporous structure to allow the dye to penetrate evenly, ensuring color consistency and durability, while preventing excessive penetration or accumulation of the dye.

[0058] As a preferred embodiment of the present invention, the calculation method of the oxide film dyeing performance index includes:

[0059] S1a, measure the oxide film thickness at multiple points, and calculate the average film thickness and thickness standard deviation;

[0060] When measuring the thickness of the oxide film, non-destructive measurement tools should be used, such as: ellipsometer, optical microscope or laser thickness gauge;

[0061] Select i measuring points on the surface of the 2A12 aluminum alloy workpiece after anodizing, and ensure that these points are evenly distributed in different areas of the workpiece to reflect the thickness variation of the entire surface;

[0062] The calculation formula for the average film thickness is:

[0063]

[0064] Where h is the average film thickness, t i is the thickness of the ith measurement point, and n is the total number of measurement points;

[0065] The thickness standard deviation is calculated as:

[0066]

[0067] Where, h is the thickness standard deviation, t is the average film thickness, and t i is the thickness of the ith measurement point, and n is the total number of measurement points;

[0068] The average film thickness determines the depth and uniformity of the dye penetrating into the oxide film. Appropriate film thickness ensures that the dye fully penetrates and forms a uniform color distribution. If the film thickness is too thin, the dye may not fully penetrate, resulting in a light color. If the film thickness is too thick, it may make it difficult for the dye to penetrate or the coloring may be uneven.

[0069] The thickness standard deviation reflects the uniformity of the oxide film thickness. A lower standard deviation means a uniform oxide film thickness, which helps the dye to penetrate evenly and avoid the phenomenon of different shades of color. If the standard deviation is large, the oxide film thickness is uneven, which may lead to poor dyeing results, or even partial undyed or over-dyed conditions.

[0070] S1b, placing the oxide film sample in an X-ray CT scanner, obtaining a high-resolution three-dimensional image, reconstructing the scan data, and generating a three-dimensional structural image of the oxide film sample; segmenting and quantitatively analyzing the three-dimensional structural image by image analysis software, and calculating the porosity;

[0071] By placing the oxide film sample in an X-ray CT scanner for high-resolution three-dimensional imaging, its internal structure can be fully evaluated without destroying the sample, the porosity can be accurately calculated, and potential quality problems can be identified. This method not only improves the accuracy and efficiency of detection, but also provides a scientific basis and technical support for optimizing production processes, predicting performance, and reducing rework. At the same time, the generated three-dimensional images are also convenient for intuitive display and communication, thereby significantly improving the quality and production efficiency of oxide film products.

[0072] Porosity directly affects the penetration ability of dyes. Appropriate porosity allows dyes to evenly penetrate the oxide film, ensuring the consistency and durability of the dyeing effect. If the porosity is too high, the dye may over-penetrate, resulting in too dark a color or dye accumulation. If the porosity is too low, the dye may not penetrate enough, resulting in light or uneven colors.

[0073] S1c, measure the roughness of the oxide film;

[0074] When measuring the roughness of the oxide film, use methods that will not damage the oxide film, such as: laser confocal microscopy, white light interferometry, atomic force microscopy, non-contact optical profilometer, etc.;

[0075] Roughness reflects the smoothness of the oxide film surface; lower roughness (i.e. smoother surface) helps the dye adhere evenly, ensuring color consistency and durability; if the surface is too rough, it may cause the dye to accumulate in certain areas, causing uneven color or fading;

[0076] S1d, weighted calculation of the four parameters of average film thickness, thickness standard deviation, porosity and roughness is performed to obtain the oxide film dyeing performance index. The calculation formula is as follows:

[0077] DPI=w a ·A+w b ·B+w c ·C+w d ·D; (1)

[0078] Among them, DPI is the oxide film dyeing performance index;

[0079] w a 、w b 、w c 、w d are the average film thickness, thickness standard deviation, porosity and roughness weights, respectively, and w a +w b +w c +w d =1; The weights of the above four parameters can be obtained by expert evaluation method, experimental verification method, hierarchical analysis method, etc.;

[0080] A, B, C, and D are the values ​​of the four parameters, namely, average film thickness, thickness standard deviation, porosity, and roughness;

[0081] By weighted calculation of average film thickness, thickness standard deviation, porosity and roughness, not only can the quality of the oxide film be comprehensively evaluated and the accuracy and reliability of the evaluation be improved, but also the process parameters can be optimized, a standardized evaluation system can be established, and the decision-making process can be simplified. This method provides important support for the quality control and performance prediction of the oxide film, and significantly improves the quality and competitiveness of the final product.

[0082] As a preferred embodiment of the present invention, a method for setting a threshold range of an oxide film dyeing performance index comprises:

[0083] S21. Collect the average film thickness, thickness standard deviation, porosity and roughness of the oxide film from the 2A12 aluminum alloy workpieces that have been successfully dyed in the past;

[0084] S22, calculating the DPI value of the successfully dyed 2A12 aluminum alloy workpiece according to formula (1);

[0085] S23, analyzing the distribution of the above DPI values ​​to find out the DPI value range of most successfully dyed 2A12 aluminum alloy workpieces;

[0086] S24, taking a 2A12 aluminum alloy workpiece sample, dyeing it within the set threshold range, verifying the validity of the oxide film dyeing performance index threshold range, and adjusting the oxide film dyeing performance index threshold range according to the experimental results;

[0087] By collecting the average film thickness, thickness standard deviation, porosity and roughness of the oxide film from previously successfully dyed 2A12 aluminum alloy workpieces, calculating its DPI value, analyzing the DPI value distribution and determining the DPI value range of most successfully dyed workpieces, and then verifying and adjusting the threshold range through experiments, this method can scientifically and reasonably set the threshold range of the oxide film dyeing performance index. This method not only ensures the accuracy of the threshold based on historical data, but also ensures its effectiveness through experimental verification, thereby optimizing process parameters, improving production efficiency and product quality, reducing the defective rate, and providing a reliable basis for subsequent production and quality control.

[0088] As a preferred embodiment of the present invention, a method for constructing an oxide film dyeing performance prediction model comprises:

[0089] S11, collecting historical data of 2A12 aluminum alloy workpieces that have been successfully dyed in the past, and preprocessing the historical data;

[0090] Specifically, historical data of 2A12 aluminum alloy workpieces that have been successfully dyed in the past are collected, which may include their average film thickness, thickness standard deviation, porosity, roughness, copper content, ambient temperature and humidity, and anodizing parameters. In order to obtain high-quality historical data, the data can be preprocessed to remove outliers, missing values, and duplicate data in the historical data. The historical data of different dimensions can be standardized through methods such as minimum-maximum normalization, standard normalization, or logarithmic transformation, so that all input data are within the same range, which is convenient for subsequent data analysis.

[0091] S12, analyzing the relationship between each data category in the historical data and the oxide film dyeing performance index by a statistical method to obtain a correlation value;

[0092] Based on the above embodiments, the relationship between each data category in the historical data and the oxide film dyeing performance index can be analyzed through statistical methods such as Pearson correlation coefficient, mutual information, and chi-square test to identify key influencing factors and provide metrics for subsequent steps, so that high-correlation categories can be used for subsequent model training and low-correlation or irrelevant data categories can be eliminated, which can effectively improve the accuracy of the prediction model and optimize the actual process flow.

[0093] S13, defining a correlation partition range, assigning data categories to corresponding intervals according to correlation values, and sorting the data categories in each interval;

[0094] S14, setting an interval screening threshold, selecting several intervals to merge according to the interval screening threshold, and obtaining a related data category;

[0095] Specifically, in order to optimize the data processing process, data categories can be divided into different intervals according to correlation values. Sorting within the interval can efficiently organize data and divide the entire feature space into multiple intervals. Only part of the data is processed in each interval, which reduces the computational complexity of global sorting and provides support for subsequent screening. According to the data density of different partitions, the size of the interval can be dynamically adjusted, and high-correlation intervals can be selected and merged through the screening threshold to further screen out the most relevant feature categories, simplify the feature set, improve the flexibility of data processing, and reduce the complexity for subsequent modeling.

[0096] S15, selecting a machine learning model as an oxide film dyeing performance prediction model, and training and optimizing the oxide film dyeing performance prediction model according to historical data of the associated data category;

[0097] S16. Deploy the optimized oxide film dyeing performance prediction model into practical applications;

[0098] Specifically, in this step, you can select machine learning models such as linear regression, random forest, neural network, etc. as the basic architecture of the model, and divide the standardized data of the associated data category into training set and validation set. Use the training set to train the machine learning model. You can adjust the hyperparameters of the machine learning model according to the change in loss during the training process. Use the test set to evaluate the performance of the trained machine learning model on unseen data. You can tune the machine learning based on the evaluation results. The tuning methods include adjusting the model architecture, modifying the loss function, and adjusting the hyperparameters.

[0099] The above method systematically collects, processes and analyzes historical data, and uses machine learning models to build a prediction model for oxide film dyeing performance. It not only ensures the accuracy and completeness of the data, but also screens out key influencing factors through standardized processing and statistical analysis. This method can accurately capture the relationship between each parameter and dyeing performance, optimize the model architecture and hyperparameters, and thus improve the accuracy and generalization ability of the prediction model. Ultimately, the model deployed in practical applications can predict the dyeing performance of oxide films in real time, significantly improve production efficiency and product quality, reduce the defective rate, and provide a scientific basis for process optimization.

[0100] As a preferred embodiment of the present invention, in step S4, the parameters of the dye BK (Wanxi: 35%-40% metal salt, 60% organic matter, and inorganic acid remainder) are: temperature 20-30°C, concentration 10-15g / L;

[0101] The double water washing method is used to remove the surface dye of 2A12 aluminum alloy workpiece;

[0102] In the temperature range of 20-30℃, the dye BK can maintain proper activity, ensuring that it evenly penetrates into the micropores of the oxide film to form a uniform and consistent color; the concentration of 10-15g / L can provide a moderate dyeing depth while ensuring the dyeing effect;

[0103] The double washing method ensures that the dye on the surface of the workpiece is thoroughly cleaned through two washing steps. The first washing can initially remove most of the residual dye, and the second washing further removes the remaining trace dye to avoid uneven dyeing or discoloration in subsequent processes.

[0104] As a preferred embodiment of the present invention, the parameters of nickel acetate sealant WBX (Wanxi: nickel acetate 75%, sodium acetate 5%, complexing agent 20%) are: temperature 70-80°C, concentration 5g / L, pH 5.0-6.0;

[0105] In the temperature range of 70-80℃, nickel acetate sealer WBX can accelerate the chemical reaction rate with the oxide film surface, ensuring that the sealer effectively fills the micropores and cracks in the oxide film; the concentration of 5g / L can provide a moderate sealer content while ensuring the sealing effect; pH 5.0-6.0 is a weakly acidic environment, which helps the nickel ions in the sealer to better bind to the oxide film surface, forming a stable sealing layer, enhancing its corrosion resistance and wear resistance.

[0106] As a preferred embodiment of the present invention, the specific method of drying and then baking comprises:

[0107] Blow dry with clean dry air and let stand for 2 hours, then bake at 85℃ with nitrogen for 30 minutes;

[0108] The above-mentioned specific method of drying and then baking not only ensures the rapid and uniform drying of the workpiece surface, but also allows the internal moisture to evaporate fully through the standing time, reducing possible problems during the baking process; nitrogen baking is carried out at a temperature of 85°C, which can not only accelerate the curing of the sealing layer, but also avoid high temperature damage and oxidation reactions, thereby ensuring the quality and stability of the sealing layer.

[0109] Compared with the prior art, the present invention has the following beneficial effects:

[0110] (1) A prediction model for the dyeing performance of oxide films was introduced. By scientifically predicting and dynamically adjusting the anodizing parameters, the ideal dyeing effect can be achieved each time. This method avoids the uncertainty caused by the reliance on experience and trial and error in traditional processes, and significantly improves the uniformity and consistency of dyeing. The prediction model can optimize the anodizing parameters in real time according to factors such as copper content, ambient temperature and humidity, ensuring that the process parameters are always within the optimal range, thereby achieving stable and high-quality dyeing effects.

[0111] (2) Anodizing forms a dense oxide film on the surface of aluminum alloy, which not only enhances the corrosion resistance of the material, but also provides a good foundation for subsequent dyeing treatment. The dyeing process further fills the micropores in the oxide film, enhances the integrity and protective effect of the film layer, and extends the service life of the workpiece; in addition, this sequence ensures that the dye can penetrate into the oxide film evenly, avoiding the problems of uneven color and poor adhesion that may be caused by direct dyeing, thereby improving the stability and durability of the dyeing effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0112] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0113] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0114] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0115] Secondly, the term "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0116] Embodiment 1:

[0117] A method for anodizing and dyeing a 2A12 aluminum alloy comprises the following steps:

[0118] S1. Determine the copper content of the 2A12 aluminum alloy workpiece to be dyed and the current ambient temperature and humidity;

[0119] Copper content: The copper content was measured to be 3.85% (wt).

[0120] Current ambient temperature and humidity: ambient temperature is 22°C, relative humidity is 50%;

[0121] S2. Setting the threshold range of the oxide film dyeing performance index;

[0122] Through historical data analysis and experimental verification, it was determined that the oxide film staining performance index threshold range is 80 to 90;

[0123] S3. Input the copper content, current ambient temperature and humidity, and anodizing parameters into the pre-built oxide film dyeing performance prediction model; the parameters are as follows:

[0124] Anodizing parameters: sulfuric acid concentration: 220g / L, aluminum ion concentration: 9g / L, electrolyte temperature: 9°C, final voltage: 18V, current density: 2.5A / dm 2 , electrolysis time: 60min;

[0125] The copper content is 3.85% (wt).

[0126] The ambient temperature is 22°C and the relative humidity is 50%;

[0127] The predicted value of the oxide film dyeing performance index calculated by the oxide film dyeing performance prediction model is 85.32, which is within the threshold range of the oxide film dyeing performance index, so there is no need to adjust the anodizing parameters;

[0128] S4, pre-processing steps:

[0129] Use 400# flocking sandpaper to grind the workpiece to remove appearance defects, and then use a scouring pad to polish the 2A12 aluminum alloy workpiece as a whole until the appearance is consistent and the finish is 0.8μm.

[0130] The 2A12 aluminum alloy workpiece was immersed in a degreasing agent with a temperature of 60°C and a concentration of 15% w / w, and ultrasonic waves were used; after being taken out, the workpiece was washed with water to remove the surface oil and degreasing agent.

[0131] S5, immerse the 2A12 aluminum alloy workpiece in a chemical polishing liquid SK at a temperature of 95°C, wash with water after treatment; then put it into a neutralizing agent CH at room temperature and a concentration of 13% w / w to remove the generated ash;

[0132] S6, placing the pretreated 2A12 aluminum alloy workpiece into an electrolyte, and treating the 2A12 aluminum alloy workpiece according to the above anodizing parameters;

[0133] S7. After anodizing, the 2A12 aluminum alloy workpiece is fully washed with water to remove the acidic substances remaining on the surface;

[0134] S8, putting the 2A12 aluminum alloy workpiece after the residual acid is removed into the dye BK for dyeing, the parameters of the dye BK are: temperature 25° C., concentration 11 g / L; after dyeing, using a double water washing method to remove the dye on the surface of the 2A12 aluminum alloy workpiece;

[0135] S9, placing the 2A12 aluminum alloy workpiece in nickel acetate sealant WBX for sealing, the parameters of the nickel acetate sealant WBX are: temperature 76°C, concentration 5g / L, pH 5.3; washing with water after sealing;

[0136] S10. Blow dry with clean dry air and let stand for 2 hours, then bake at 85°C with nitrogen for 30 minutes; then inspect the appearance of the 2A12 aluminum alloy workpiece.

[0137] Embodiment 2:

[0138] A method for anodizing and dyeing a 2A12 aluminum alloy comprises the following steps:

[0139] S1. Determine the copper content of the 2A12 aluminum alloy workpiece to be dyed and the current ambient temperature and humidity;

[0140] Copper content: The copper content was measured to be 4.8% (wt).

[0141] Current ambient temperature and humidity: ambient temperature is 23°C, relative humidity is 50%;

[0142] S2. Setting the threshold range of the oxide film dyeing performance index;

[0143] Through historical data analysis and experimental verification, it was determined that the oxide film staining performance index threshold range is 80 to 90;

[0144] S3, input the copper content, current ambient temperature and humidity, and anodizing parameters into a pre-constructed oxide film dyeing performance prediction model; the parameters are as follows (the same as in Example 1):

[0145] Anodizing parameters: sulfuric acid concentration: 220g / L, aluminum ion concentration: 9g / L, electrolyte temperature: 9°C, final voltage: 18V, current density: 2.5A / dm 2 , electrolysis time: 60min;

[0146] The copper content is 4.8% (wt).

[0147] The ambient temperature is 23°C and the relative humidity is 50%;

[0148] The predicted value of the oxide film dyeing performance index calculated by the oxide film dyeing performance prediction model is 95.36, which is outside the threshold range of the oxide film dyeing performance index, and the anodizing parameters need to be adjusted;

[0149] The final anodizing parameters were adjusted to: sulfuric acid concentration: 190 g / L, aluminum ion concentration: 8 g / L, electrolyte temperature: 8.5 °C, final voltage: 18 V, current density: 2.0 A / dm 2 , electrolysis time: 55min;

[0150] S4, pre-processing steps:

[0151] Use 400# flocking sandpaper to grind the workpiece to remove appearance defects, and then use a scouring pad to polish the 2A12 aluminum alloy workpiece as a whole until the appearance is consistent and the finish is 0.6μm.

[0152] The 2A12 aluminum alloy workpiece was immersed in a degreasing agent with a temperature of 58°C and a concentration of 15% w / w, and ultrasonic waves were used; after being taken out, the workpiece was washed with water to remove the surface oil and degreasing agent.

[0153] S5, immerse the 2A12 aluminum alloy workpiece in a chemical polishing liquid SK at a temperature of 93°C, wash with water after treatment; then put it into a neutralizing agent CH at room temperature and a concentration of 12% w / w to remove the generated ash;

[0154] S6, placing the pretreated 2A12 aluminum alloy workpiece into an electrolyte, and treating the 2A12 aluminum alloy workpiece according to the above anodizing parameters;

[0155] S7. After anodizing, the 2A12 aluminum alloy workpiece is fully washed with water to remove the acidic substances remaining on the surface;

[0156] S8, putting the 2A12 aluminum alloy workpiece after the residual acid is removed into the dye BK for dyeing, the parameters of the dye BK are: temperature 24° C., concentration 10 g / L; after dyeing, using a double water washing method to remove the dye on the surface of the 2A12 aluminum alloy workpiece;

[0157] S9, placing the 2A12 aluminum alloy workpiece in nickel acetate sealant WBX for sealing, the parameters of the nickel acetate sealant WBX are: temperature 75°C, concentration 4.5g / L, pH 5.2; washing with water after sealing;

[0158] S10. Blow dry with clean dry air and let stand for 2 hours, then bake at 85°C with nitrogen for 30 minutes; then inspect the appearance of the 2A12 aluminum alloy workpiece.

[0159] The workpieces obtained in Example 1 and Example 2 were inspected for appearance and no defective products were found.

[0160] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for anodizing and dyeing 2A12 aluminum alloy, characterized in that: The following steps are involved: S1, measuring the copper content of the 2A12 aluminum alloy workpiece to be dyed and the current ambient temperature and humidity, inputting the copper content, the current ambient temperature and humidity and the anodizing parameters into a pre-constructed oxide film dyeing performance prediction model to obtain an oxide film dyeing performance index prediction value; S2, setting the oxide film dyeing performance index threshold range, if the oxide film dyeing performance index prediction value is outside the oxide film dyeing performance index threshold range, adjusting the anodizing parameters and re-obtaining the oxide film dyeing performance index prediction value, until the oxide film dyeing performance index prediction value is within the oxide film dyeing performance index threshold range, and then performing pretreatment and anodizing treatment on the 2A12 aluminum alloy workpiece to be dyed; S3. After anodizing, the 2A12 aluminum alloy workpiece is washed with water to remove residual acid; S4, putting the 2A12 aluminum alloy workpiece after the residual acid is removed into the dye BK for dyeing, and after dyeing, washing with water to remove the dye on the surface of the 2A12 aluminum alloy workpiece; S5, placing the 2A12 aluminum alloy workpiece into nickel acetate sealant WBX for hole sealing, and washing with water after the hole sealing is completed; S6. Bake after drying, and then inspect the appearance of the 2A12 aluminum alloy workpiece.

2. The method for anodizing and dyeing 2A12 aluminum alloy according to claim 1, characterized in that: The pre-processing method in step S2 comprises: S21. Remove surface defects of 2A12 aluminum alloy workpiece by physical polishing and grinding; S22, then remove the oil stains on the surface of the 2A12 aluminum alloy workpiece; S23. After removing oil stains and defects, the 2A12 aluminum alloy workpiece is chemically polished.

3. The method for anodizing and dyeing 2A12 aluminum alloy according to claim 2, characterized in that: The physical polishing method comprises: Use 400# flocking sandpaper to grind the workpiece to remove appearance defects, and then use a scouring pad to polish the 2A12 aluminum alloy workpiece as a whole until the appearance is consistent, with a finish of ≤0.8um; The method for removing oil stains from the surface of a 2A12 aluminum alloy workpiece comprises: Immerse the 2A12 aluminum alloy workpiece in a degreasing agent with a temperature of 50-60°C and a concentration of 15% w / w, and use ultrasonic waves; remove the workpiece and wash it with water to remove the surface oil and degreasing agent; The chemical polishing method comprises: The 2A12 aluminum alloy workpiece is immersed in a chemical polishing liquid SK at a temperature of 90-100°C, and washed with water after treatment; then placed in a neutralizing agent CH at room temperature and a concentration of 10-20% w / w to remove the generated ash.

4. The method for anodizing and dyeing 2A12 aluminum alloy according to claim 1, characterized in that: The method of anodizing in step S2 comprises: S2a, equipped with the following electrolyte: sulfuric acid concentration: 180-220g / L, aluminum ion concentration <10g / L; and the electrolyte temperature is controlled at 8-10℃; S2b, the voltage is set to climb for 5 minutes, and the final voltage is 18V; S2c, place the pretreated 2A12 aluminum alloy workpiece into the electrolyte, and control the current density at 1-3A / dm 2 The electrolysis time is 50-70min; the thickness of the obtained oxide film is 10-15um.

5. The method for anodizing and dyeing 2A12 aluminum alloy according to claim 1, characterized in that: The calculation method of the oxide film dyeing performance index comprises: S1a, measure the oxide film thickness at multiple points, and calculate the average film thickness and thickness standard deviation; S1b, placing the oxide film sample in an X-ray CT scanner, obtaining a high-resolution three-dimensional image, reconstructing the scan data, and generating a three-dimensional structural image of the oxide film sample; segmenting and quantitatively analyzing the three-dimensional structural image by image analysis software, and calculating the porosity; S1c, measure the roughness of the oxide film; S1d, weighted calculation of the four parameters of average film thickness, thickness standard deviation, porosity and roughness is performed to obtain the oxide film dyeing performance index. The calculation formula is as follows: DPI=w a ·A+w b ·B+w c ·C+w d ·D; (1) Among them, DPI is the oxide film dyeing performance index; w a 、w b 、w c 、w d are the average film thickness, thickness standard deviation, porosity and roughness weights, respectively, and w a +w b +w c +w d =1; A, B, C, and D are the values ​​of the four parameters, namely, average film thickness, thickness standard deviation, porosity, and roughness, respectively.

6. The method for anodizing and dyeing 2A12 aluminum alloy according to claim 5, characterized in that: The method for setting the threshold range of the oxide film staining performance index comprises: S21. Collect the average film thickness, thickness standard deviation, porosity and roughness of the oxide film from the 2A12 aluminum alloy workpieces that have been successfully dyed in the past; S22, calculating the DPI value of the successfully dyed 2A12 aluminum alloy workpiece according to formula (1); S23, analyzing the distribution of the above DPI values ​​to find out the DPI value range of most successfully dyed 2A12 aluminum alloy workpieces; S24. Take a 2A12 aluminum alloy workpiece sample and dye it within the set threshold range to verify the validity of the oxide film dyeing performance index threshold range, and adjust the oxide film dyeing performance index threshold range based on the experimental results.

7. The method for anodizing and dyeing 2A12 aluminum alloy according to claim 1, characterized in that: The method for constructing the oxide film dyeing performance prediction model comprises: S11, collecting historical data of 2A12 aluminum alloy workpieces that have been successfully dyed in the past, and preprocessing the historical data; S12, analyzing the relationship between each data category in the historical data and the oxide film dyeing performance index by a statistical method to obtain a correlation value; S13, defining a correlation partition range, assigning the data categories to corresponding intervals according to the correlation values, and sorting the data categories in each interval; S14, setting an interval screening threshold, selecting a number of intervals according to the interval screening threshold for merging, and obtaining a related data category; S15, selecting a machine learning model as the oxide film dyeing performance prediction model, and training and optimizing the oxide film dyeing performance prediction model according to the historical data of the associated data category; S16. Deploy the optimized oxide film dyeing performance prediction model into practical applications.

8. The method for anodizing and dyeing 2A12 aluminum alloy according to claim 1, characterized in that: In step S4, the parameters of the dye BK are: temperature 20-30°C, concentration 10-15 g / L; The double water washing method is used to remove the surface dye of 2A12 aluminum alloy workpiece.

9. The method for anodizing and dyeing 2A12 aluminum alloy according to claim 1, characterized in that: The parameters of the nickel acetate sealant WBX are: temperature 70-80° C., concentration 5 g / L, and pH 5.0-6.

0.

10. The method for anodizing and dyeing 2A12 aluminum alloy according to claim 1, characterized in that: The specific method of post-blow drying and baking comprises: After blowing dry with clean dry air and leaving it to stand for 2 hours, it was baked at 85°C with nitrogen for 30 minutes.

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