An environmentally friendly chemical copper plating solution for die-cast aluminum alloys and its copper plating method
By using an environmentally friendly chemical copper plating solution to treat die-cast aluminum alloys, the pretreatment before electroplating is simplified, the grain fineness and adhesion of the coating are improved, the complexity and pollution problems of the secondary zinc immersion process are solved, and an environmentally friendly and efficient copper plating effect is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANCHANG HANGKONG UNIVERSITY
- Filing Date
- 2023-06-06
- Publication Date
- 2026-06-30
AI Technical Summary
In the existing electroplating process for die-cast aluminum alloys, the secondary zinc immersion process is cumbersome, time-consuming, and difficult to analyze and maintain the plating solution. Furthermore, the traditional copper plating solution contains sodium hypophosphite, which may lead to eutrophication of the water body.
An environmentally friendly chemical copper plating solution is used, consisting of copper salts, complexing agents, surfactants, and pH adjusters. Die-cast aluminum alloy components are treated with a specific process, simplifying pre-plating treatment and avoiding phosphorus contamination.
It simplifies the pretreatment process for electroplating, reduces costs, improves the fineness and adhesion of the coating grains, reduces hydrogen bubble retention, produces a uniform coating without heating, and is environmentally friendly with no phosphorus emissions.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to the field of C23C18 / 16 technology, specifically to an environmentally friendly chemical copper plating solution for die-cast aluminum alloys and its copper plating method. Background Technology
[0002] Die-cast aluminum alloys generally contain more alloying elements than their wrought counterparts, resulting in superior performance. They can be directly manufactured into complex shapes using metal forming processes, eliminating the need for large and complex machining equipment. This offers advantages such as saving metal resources, reducing costs, and minimizing labor time, leading to their widespread application in both aerospace and civilian industries. Before use, die-cast aluminum alloy components typically require surface treatment. Electroplating is one of the most common methods, imparting excellent protective and decorative properties, extending service life, and expanding application range. The electroplating process for die-cast aluminum alloy components usually involves a secondary zinc immersion pretreatment to enhance the adhesion between the plating layer and the die-cast aluminum alloy. The purpose of zinc immersion is to remove the oxide film from the workpiece surface while forming a dense, uniform zinc replacement layer. This prevents the aluminum surface from being re-oxidized, shifting the surface electrode potential of the aluminum in the positive direction. This overcomes the displacement reaction between the aluminum substrate and metal ions in the plating solution, ensuring a strong bond between the plating layer and the die-cast aluminum alloy substrate. However, the secondary zinc immersion process is cumbersome and complex, takes a long time, and is difficult to analyze and maintain.
[0003] It has been found that copper plating by displacement of die-cast aluminum alloys can eliminate the need for secondary zinc immersion and stripping processes, simplifying the electroplating production process of die-cast aluminum alloys, reducing production costs, protecting the environment, and reducing pollution emissions. However, there is very little research on copper plating by displacement of die-cast aluminum alloys. Kang Ruixue et al. used a choline chloride-ethylene glycol eutectic system to prepare a copper layer on the surface of die-cast aluminum alloys by immersion, but this method takes too long and cannot be practically applied. Chinese patent application number 201710149761.7 discloses a copper plating solution and a copper plating method, providing an ethylenediamine system for copper plating by displacement to replace secondary zinc immersion. However, the copper plating solution contains sodium hypophosphite, and if the phosphorus content in the wastewater exceeds the standard, it will accelerate the eutrophication of water bodies.
[0004] Therefore, providing an environmentally friendly, phosphorus-free copper plating solution and its copper plating method for die-cast aluminum alloys is currently the main technical problem that needs to be solved. Summary of the Invention
[0005] To address the above problems, the first aspect of this invention provides an environmentally friendly chemical copper plating solution for die-cast aluminum alloys. The solvent of the environmentally friendly chemical copper plating solution is water, and its components, by mass concentration, include 30-40 g / L of copper salt, 40-75 g / L of complexing agent, 0.5-1 g / L of surfactant, and 5-15 g / L of pH adjuster.
[0006] The copper salt is selected from one or more of copper sulfate pentahydrate, copper chloride, copper nitrate, and copper carbonate.
[0007] The CAS number for the copper sulfate pentahydrate is 7758-99-8.
[0008] Preferably, the solvent of the environmentally friendly chemical copper plating solution is deionized water.
[0009] Preferably, the preparation method of the environmentally friendly chemical copper plating solution includes the following steps:
[0010] Add copper salt and complexing agent to a beaker, add water and stir until fully dissolved, then add surfactant and stir. After stirring until dissolved, add pH adjuster to adjust the pH value to 8.5±0.5 to obtain environmentally friendly chemical copper plating solution.
[0011] Furthermore, the preparation method of the environmentally friendly chemical copper plating solution includes the following steps:
[0012] Add copper sulfate pentahydrate and complexing agent to a beaker, add deionized water and stir until fully dissolved, then add surfactant and stir. After stirring until dissolved, add pH adjuster to adjust the pH value to 8.5±0.5 to obtain environmentally friendly chemical copper plating solution.
[0013] Preferably, the complexing agent is selected from one or more of trisodium citrate, disodium ethylenediaminetetraacetate, and potassium sodium tartrate.
[0014] To improve the fineness of the deposited coating grains, as well as the brightness and adhesion of the coating, the inventors discovered during experiments that by using trisodium citrate, disodium ethylenediaminetetraacetate, and potassium sodium tartrate as complexing agents in this application, the anions in these substances can complex with copper ions in the copper plating solution during the surface copper plating treatment of die-cast aluminum alloys. This reduces the concentration of free copper ions in the copper plating solution, thereby reducing the rate of the displacement reaction, further refining the grains of the deposited coating, improving the brightness of the coating, and further enhancing the adhesion between the coating and the die-cast aluminum alloy.
[0015] Preferably, the surfactant is an anionic surfactant.
[0016] Preferably, the anionic surfactant is selected from one or more of sodium dodecylbenzenesulfonate, sodium dialkyl sulfate, sodium dodecyl sulfonate, sodium tetradecylbenzenesulfonate, sodium hexadecylbenzenesulfonate, and sodium octadecylbenzenesulfonate.
[0017] Furthermore, the anionic surfactant is sodium dodecylbenzenesulfonate.
[0018] To improve the adhesion between the copper plating layer and the die-cast aluminum alloy substrate after copper plating, the inventors discovered during experiments that when using an Al-Si-Cu die-cast aluminum alloy with a silicon content of 7.5–12% and a copper content of 1.5–4%, sodium dodecylbenzenesulfonate can be used as a surfactant during the copper plating process. Sodium dodecylbenzenesulfonate can reduce the interfacial tension of the copper plating solution, making it difficult for hydrogen bubbles generated by the corrosion reaction to remain on the surface of the die-cast aluminum alloy, thereby effectively improving the adhesion between the replacement copper plating layer and the die-cast aluminum alloy substrate.
[0019] Preferably, the pH adjuster is one or a combination of sodium hydroxide and potassium hydroxide.
[0020] To improve the adhesion between the copper plating layer and the die-cast aluminum alloy substrate, the inventors discovered during experiments that by using sodium hydroxide or potassium hydroxide as a pH adjuster to a pH of 8.5±0.5, coarse plating crystals and poor adhesion were avoided. The possible reason is that die-cast aluminum alloy is an amphoteric metal that can react with alkalis, and the displacement reaction rate is very fast under acidic conditions, which easily leads to coarse plating crystals, poor gloss and adhesion; under strong alkaline conditions, it is easy to corrode the die-cast aluminum alloy substrate, resulting in poor adhesion as well.
[0021] A second aspect of the present invention provides a copper plating method for die-cast aluminum alloys, wherein the die-cast aluminum alloys are surface-treated using an environmentally friendly chemical copper plating solution.
[0022] Preferably, the copper plating method for the die-cast aluminum alloy includes the following steps:
[0023] S1: Place the die-cast aluminum alloy components in a degreasing solution to remove oil. The temperature of the degreasing solution is 70-80℃ and the degreasing time is 3-8 minutes. Then rinse them clean with running water and pure water in sequence.
[0024] S2: Place the die-cast aluminum alloy component in a whitening solution for whitening treatment. The temperature of the whitening solution is 15-45℃, and the whitening treatment time is 2-6 minutes. Rinse it clean with running water and pure water in sequence.
[0025] S3: Immerse the die-cast aluminum alloy components, after degreasing and whitening treatment, in an environmentally friendly chemical copper plating solution for 5-10 minutes. The temperature of the environmentally friendly chemical copper plating solution is 20-35℃, and the pH value is 8.5±0.5.
[0026] S4: Clean with deionized water and dry for later use.
[0027] Preferably, the whitening solution contains ammonium bifluoride and hydrogen peroxide solution.
[0028] Preferably, the ammonium bifluoride concentration in the whitening solution is 100-300 g / L, and the whitening solution contains 150-250 mL / L of hydrogen peroxide solution with a hydrogen peroxide volume fraction of 15-35%.
[0029] Furthermore, the solvent for the whitening liquid is water.
[0030] Furthermore, the whitening solution contains ammonium bifluoride with a mass concentration of 200 g / L, and the whitening solution contains a hydrogen peroxide solution with a volume fraction of 15-35% at 200 mL / L.
[0031] The hydrogen peroxide solution contains 30% hydrogen peroxide by volume.
[0032] Preferably, the die-cast aluminum alloy is an Al-Si-Cu series die-cast aluminum alloy with a silicon content of 7.5-12% and a copper content of 1.5-4%.
[0033] To improve the rate of aluminum replacement copper plating in die-cast aluminum alloys and enhance the adhesion between the copper plating layer and the die-cast aluminum alloy substrate, the inventors discovered during experiments that after degreasing the surface of die-cast aluminum alloy components with a degreasing solution, a whitening solution containing 100–300 g / L ammonium bifluoride and 15–25% hydrogen peroxide was applied to the surface for whitening treatment. This was particularly effective for die-cast aluminum alloy components with a silicon content of 7.5–12% and a copper content of 1.5–4%. The whitening solution effectively removed silicon from the surface of the die-cast aluminum alloy components, reducing the impact of silicon on the activity of the die-cast aluminum alloy and the adhesion to the plating layer. Furthermore, during the copper plating process, the copper in the die-cast aluminum alloy substrate could form localized corrosion cells with the aluminum, increasing the rate of aluminum replacement copper plating. A copper content of 1.5–4% in the die-cast aluminum alloy further improved the adhesion between the copper plating layer and the die-cast aluminum alloy substrate.
[0034] Beneficial effects
[0035] 1. In this invention, a copper plating solution with environmentally friendly components can be obtained by using specific complexing agents, surfactants, and pH adjusters.
[0036] 2. By using the environmentally friendly chemical copper plating solution provided in this invention, the deposited coating has fine grains and good brightness and adhesion.
[0037] 3. By using the environmentally friendly chemical copper plating solution provided in this invention, the hydrogen bubbles generated by the corrosion reaction are difficult to remain on the surface of the die-cast aluminum alloy, effectively improving the bonding force between the replacement copper plating layer and the die-cast aluminum alloy substrate.
[0038] 4. By adopting the copper plating method for die-cast aluminum alloys provided in this invention, the secondary zinc immersion process in the pretreatment of die-cast aluminum alloys for electroplating can be effectively replaced, simplifying the pretreatment process of die-cast aluminum alloys for electroplating, saving costs, and making the operation simple.
[0039] 5. By adopting the copper plating method for die-cast aluminum alloys provided in this invention, the technical effects of simple process, fast replacement speed, uniform coating and good adhesion are achieved.
[0040] 6. By adopting the copper plating method for die-cast aluminum alloys provided in this invention, a large temperature range is achieved during the copper plating process, no heating is required, and no harmful substances are generated during use. Attached Figure Description
[0041] Figure 1 Example 1 of this invention uses die-cast aluminum alloy ADC10, and the surface macroscopic morphology after replacement copper plating treatment is shown in the figure.
[0042] Figure 2 Example 2 of this invention uses die-cast aluminum alloy ADC10, and the surface macroscopic morphology is shown after replacement copper plating and thermal shock test treatment.
[0043] Figure 3 Example 3 of this invention uses die-cast aluminum alloy ADC12, which undergoes copper replacement plating followed by nickel electroplating. This is a macroscopic surface morphology image.
[0044] Figure 4 Example 4 of this invention uses die-cast aluminum alloy ADC12, which is replaced by copper plating, then electroplated with nickel, and then subjected to thermal shock test. The surface macroscopic morphology is shown in the figure. Detailed Implementation
[0045] The die-cast aluminum alloy components used in Examples 1-4 are die-cast aluminum alloy test pieces.
[0046] Example 1
[0047] The first aspect of this embodiment provides an environmentally friendly chemical copper plating solution for die-cast aluminum alloys. The solvent of the environmentally friendly chemical copper plating solution is water, and its components, by mass concentration, include 30 g / L copper sulfate pentahydrate, 50 g / L complexing agent, 0.5 g / L surfactant, and 15 g / L pH adjuster.
[0048] The preparation method of the environmentally friendly chemical copper plating solution includes the following steps:
[0049] Add copper sulfate pentahydrate and complexing agent to a beaker, add deionized water and stir until fully dissolved, then add surfactant and stir. After stirring until dissolved, add pH adjuster to adjust the pH value to 8.5±0.5 to obtain environmentally friendly chemical copper plating solution.
[0050] The CAS number for the copper sulfate pentahydrate is 7758-99-8.
[0051] The complexing agent is potassium sodium tartrate.
[0052] The surfactant is sodium dodecylbenzenesulfonate.
[0053] The pH adjuster is sodium hydroxide.
[0054] The second aspect of this embodiment provides a copper plating method for die-cast aluminum alloys, wherein the die-cast aluminum alloys are surface-treated using an environmentally friendly chemical copper plating solution.
[0055] The copper plating method for die-cast aluminum alloys includes the following steps:
[0056] S1: Place the die-cast aluminum alloy component in a degreasing solution at a temperature of 70°C for 5 minutes, and then rinse it with running water and pure water in sequence.
[0057] S2: Place the die-cast aluminum alloy component in a whitening solution for whitening treatment. The temperature of the whitening solution is 30℃ and the whitening treatment time is 4 minutes. Rinse it clean with running water and pure water in sequence.
[0058] S3: Immerse the die-cast aluminum alloy components, which have undergone degreasing and whitening treatment, in an environmentally friendly chemical copper plating solution for 5 minutes. The temperature of the environmentally friendly chemical copper plating solution is 30℃ and the pH value is 8.5.
[0059] S4: Clean with deionized water and dry for later use.
[0060] The solvent of the whitening solution is water, the whitening solution contains ammonium fluoride with a mass concentration of 200 g / L, and the whitening solution contains 200 mL / L of hydrogen peroxide solution with a volume fraction of 30%.
[0061] The die-cast aluminum alloy is die-cast aluminum alloy ADC10.
[0062] Example 2
[0063] The first aspect of this embodiment provides an environmentally friendly chemical copper plating solution for die-cast aluminum alloys. The solvent of the environmentally friendly chemical copper plating solution is water, and its components, by mass concentration, include 30 g / L copper sulfate pentahydrate, 60 g / L complexing agent, 0.8 g / L surfactant, and 10 g / L pH adjuster.
[0064] The preparation method of the environmentally friendly chemical copper plating solution includes the following steps:
[0065] Add copper sulfate pentahydrate and complexing agent to a beaker, add deionized water and stir until fully dissolved, then add surfactant and stir. After stirring until dissolved, add pH adjuster to adjust the pH value to 8.0 to obtain environmentally friendly chemical copper plating solution.
[0066] The CAS number for the copper sulfate pentahydrate is 7758-99-8.
[0067] The complexing agent is disodium oxalate tetraacetate and potassium sodium tartrate, and the mass ratio of disodium oxalate tetraacetate and potassium sodium tartrate is 1:5.
[0068] The surfactant is sodium dodecylbenzenesulfonate.
[0069] The pH adjuster is sodium hydroxide.
[0070] The second aspect of this embodiment provides a copper plating method for die-cast aluminum alloys, wherein the die-cast aluminum alloys are surface-treated using an environmentally friendly chemical copper plating solution.
[0071] The copper plating method for die-cast aluminum alloys includes the following steps:
[0072] S1: Place the die-cast aluminum alloy component in a degreasing solution at a temperature of 70°C for 5 minutes, and then rinse it with running water and pure water in sequence.
[0073] S2: Place the die-cast aluminum alloy component in a whitening solution for whitening treatment. The temperature of the whitening solution is 30℃ and the whitening treatment time is 4 minutes. Rinse it clean with running water and pure water in sequence.
[0074] S3: Immerse the die-cast aluminum alloy components, which have undergone degreasing and whitening treatment, in an environmentally friendly chemical copper plating solution for 10 minutes. The temperature of the environmentally friendly chemical copper plating solution is 30℃ and the pH value is 8.0.
[0075] S4: Clean with deionized water and dry for later use.
[0076] The solvent of the whitening solution is water, and the whitening solution contains ammonium fluoride with a mass concentration of 200 g / L and a hydrogen peroxide solution with a volume fraction of 30% at 200 mL / L.
[0077] The die-cast aluminum alloy is die-cast aluminum alloy ADC10.
[0078] Example 3
[0079] The first aspect of this embodiment provides an environmentally friendly chemical copper plating solution for die-cast aluminum alloys. The solvent of the environmentally friendly chemical copper plating solution is water, and its components, by mass concentration, include 35 g / L copper sulfate pentahydrate, 70 g / L complexing agent, 1 g / L surfactant, and 15 g / L pH adjuster.
[0080] The preparation method of the environmentally friendly chemical copper plating solution includes the following steps:
[0081] Add copper sulfate pentahydrate and complexing agent to a beaker, add deionized water and stir until fully dissolved, then add surfactant and stir. After stirring and dissolving, add pH adjuster to adjust the pH value to 8.8 to obtain environmentally friendly chemical copper plating solution.
[0082] The CAS number for the copper sulfate pentahydrate is 7758-99-8.
[0083] The complexing agent is disodium oxalate tetraacetate and potassium sodium tartrate, and the mass ratio of disodium oxalate tetraacetate and potassium sodium tartrate is 1:2.5.
[0084] The surfactant is sodium dodecylbenzenesulfonate.
[0085] The pH adjuster is sodium hydroxide.
[0086] The second aspect of this embodiment provides a copper plating method for die-cast aluminum alloys, wherein the die-cast aluminum alloys are surface-treated using an environmentally friendly chemical copper plating solution.
[0087] The copper plating method for die-cast aluminum alloys includes the following steps:
[0088] S1: Place the die-cast aluminum alloy component in a degreasing solution at a temperature of 70°C for 5 minutes, and then rinse it with running water and pure water in sequence.
[0089] S2: Place the die-cast aluminum alloy component in a whitening solution for whitening treatment. The temperature of the whitening solution is 30℃ and the whitening treatment time is 4 minutes. Rinse it clean with running water and pure water in sequence.
[0090] S3: The die-cast aluminum alloy components, after degreasing and whitening treatment, are immersed in an environmentally friendly chemical copper plating solution for 10 minutes for copper plating. The temperature of the environmentally friendly chemical copper plating solution is 30℃ and the pH value is 8.8.
[0091] S4: Clean with deionized water and dry for later use.
[0092] The solvent of the whitening solution is water, the whitening solution contains ammonium fluoride with a mass concentration of 200 g / L, and the whitening solution contains 200 mL / L of hydrogen peroxide solution with a volume fraction of 30%.
[0093] The die-cast aluminum alloy is die-cast aluminum alloy ADC12.
[0094] Example 4
[0095] The first aspect of this embodiment provides an environmentally friendly chemical copper plating solution for die-cast aluminum alloys. The solvent of the environmentally friendly chemical copper plating solution is water, and its components, by mass concentration, include 38 g / L copper sulfate pentahydrate, 75 g / L complexing agent, 1 g / L surfactant, and 12 g / L pH adjuster.
[0096] The preparation method of the environmentally friendly chemical copper plating solution includes the following steps:
[0097] Add copper sulfate pentahydrate and complexing agent to a beaker, add deionized water and stir until fully dissolved, then add surfactant and stir. After stirring until dissolved, add pH adjuster to adjust the pH value to 8.5 to obtain environmentally friendly chemical copper plating solution.
[0098] The CAS number for the copper sulfate pentahydrate is 7758-99-8.
[0099] The complexing agent is disodium oxalate tetraacetate and potassium sodium tartrate, and the mass ratio of disodium oxalate tetraacetate and potassium sodium tartrate is 1:4.
[0100] The surfactant is sodium dodecylbenzenesulfonate.
[0101] The pH adjuster is potassium hydroxide.
[0102] The second aspect of this embodiment provides a copper plating method for die-cast aluminum alloys, wherein the die-cast aluminum alloys are surface-treated using an environmentally friendly chemical copper plating solution.
[0103] The copper plating method for die-cast aluminum alloys includes the following steps:
[0104] S1: Place the die-cast aluminum alloy component in a degreasing solution at a temperature of 70°C for 5 minutes, and then rinse it with running water and pure water in sequence.
[0105] S2: Place the die-cast aluminum alloy component in a whitening solution for whitening treatment. The temperature of the whitening solution is 30℃ and the whitening treatment time is 4 minutes. Rinse it clean with running water and pure water in sequence.
[0106] S3: The die-cast aluminum alloy components, after degreasing and whitening treatment, are immersed in an environmentally friendly chemical copper plating solution for 8 minutes for copper plating treatment. The temperature of the environmentally friendly chemical copper plating solution is 30℃ and the pH value is 8.5.
[0107] S4: Clean with deionized water and dry for later use.
[0108] The solvent of the whitening solution is water, and the whitening solution contains ammonium fluoride with a mass concentration of 200 g / L and a hydrogen peroxide solution with a volume fraction of 30% at 200 mL / L.
[0109] The die-cast aluminum alloy is die-cast aluminum alloy ADC12.
[0110] Performance testing
[0111] 1. Appearance Test
[0112] The surface coatings of the die-cast aluminum alloy specimens treated with environmentally friendly chemical copper plating solution in Examples 1-4 were subjected to appearance testing. The test results are shown in Table 1. The morphological images of the die-cast aluminum alloy specimens surface-treated with environmentally friendly chemical copper plating solution in Example 1 are shown in Table 1. Figure 1 .
[0113] Table 1
[0114]
[0115]
[0116] 2. Thermal shock test
[0117] The die-cast aluminum alloy specimens surface-treated with environmentally friendly chemical copper plating solution in Example 2 were placed in a 250°C oven and baked for 3 hours. Afterward, the specimens were removed, placed in 25°C water, rinsed with deionized water, dried, and their surface morphology observed. The test results are shown in Table 2, and the morphology images are shown below. Figure 2 .
[0118] Table 2
[0119] Test Project Example 2 Appearance No bubbling or peeling
[0120] Through Table 2 and Figure 2 The test results show that after prolonged high-temperature baking and rapid cooling, the copper-plated aluminum alloy test piece obtained by surface treatment with environmentally friendly chemical copper plating solution in this application does not exhibit blistering or peeling of the copper plating layer on its surface, and the copper plating layer has good adhesion to the substrate.
[0121] 3. Appearance test after nickel plating
[0122] The die-cast aluminum alloy sample obtained by surface treatment with an environmentally friendly chemical copper plating solution in Example 3 was placed into a nickel plating solution for surface nickel plating. The nickel plating solution contained nickel sulfate (260-300 g / L), nickel chloride (35-45 g / L), and boric acid (40-50 g / L). The pH value of the nickel plating solution was 3.9, the plating temperature was 35°C, and the plating time was 30 minutes. After rinsing with deionized water, the sample was dried and the surface morphology was observed. The test results are shown in [Figure number missing]. Figure 3 .
[0123] pass Figure 3 It can be seen that the copper-plated die-cast aluminum alloy specimen obtained in Example 3 has a bright and smooth surface after being further nickel-plated, without bubbling or peeling.
[0124] 4. Nickel plating thermal shock test
[0125] The die-cast aluminum alloy specimen obtained by surface treatment with environmentally friendly chemical copper plating solution in Example 4 was processed using the following steps:
[0126] S1. The die-cast aluminum alloy sample obtained by surface treatment with an environmentally friendly chemical copper plating solution is placed in a nickel plating solution for surface nickel plating. The nickel plating solution contains nickel sulfate at a mass concentration of 260-300 g / L, nickel chloride at a mass concentration of 35-45 g / L, and boric acid at a mass concentration of 40-50 g / L. The pH value of the nickel plating solution is 3.9, the nickel plating temperature is 35℃, the nickel plating time is 60 min, and then it is rinsed with deionized water.
[0127] S2. Place the die-cast aluminum alloy test piece in a 250℃ oven and bake for 3 hours. Then, take out the die-cast aluminum alloy test piece, place it in 25℃ water, wash it with deionized water, and blow it dry.
[0128] The surface morphology of the die-cast aluminum alloy specimens after drying was observed. (See the morphology diagram below.) Figure 4 .
[0129] pass Figure 4 It can be seen that after prolonged high-temperature baking and rapid cooling, the coating on the sample surface showed no blistering, peeling, or flaking, indicating that the copper coating and nickel coating had good adhesion, and the die-cast aluminum alloy sample had good adhesion to the replacement copper coating.
Claims
1. A copper plating method for die-cast aluminum alloys, characterized in that, Includes the following steps: S1: Place the die-cast aluminum alloy components in a degreasing solution to remove oil. The temperature of the degreasing solution is 70-80℃ and the degreasing time is 3-8 minutes. Then rinse them clean with running water and pure water in sequence. S2: Place the die-cast aluminum alloy component in a whitening solution for whitening treatment. The temperature of the whitening solution is 15-45℃, and the whitening treatment time is 2-6 minutes. Rinse it clean with running water and pure water in sequence. S3: Immerse the die-cast aluminum alloy components, after degreasing and whitening treatment, in an environmentally friendly chemical copper plating solution for 5-10 minutes. The temperature of the environmentally friendly chemical copper plating solution is 20-35℃, and the pH value is 8.5±0.
5. S4: Clean with deionized water and dry for later use; The solvent of the environmentally friendly chemical copper plating solution is water, and its components, by mass concentration, include 30-40 g / L copper salt, 40-75 g / L complexing agent, 0.5-1 g / L surfactant, and 5-15 g / L pH adjuster. The complexing agent is selected from one or more of trisodium citrate, disodium ethylenediaminetetraacetate, and potassium sodium tartrate. The surfactant is sodium dodecylbenzenesulfonate; The whitening solution contains ammonium bifluoride and hydrogen peroxide; the mass concentration of ammonium bifluoride in the whitening solution is 100-300 g / L, and the whitening solution contains 150-250 mL / L of hydrogen peroxide solution with a hydrogen peroxide volume fraction of 15-35%. The die-cast aluminum alloy is an Al-Si-Cu series die-cast aluminum alloy with a silicon content of 7.5-12% and a copper content of 1.5-4%.
2. The copper plating method for die-cast aluminum alloys as described in claim 1, characterized in that, The preparation method of the environmentally friendly chemical copper plating solution includes the following steps: Add copper salt and complexing agent to a beaker, add water and stir until fully dissolved, then add surfactant and stir. After stirring until dissolved, add pH adjuster to adjust the pH value to 8.5±0.5 to obtain environmentally friendly chemical copper plating solution.
3. The copper plating method for die-cast aluminum alloys as described in claim 1, characterized in that, The copper salt is selected from one or more of copper sulfate pentahydrate, copper chloride, copper nitrate, and copper carbonate.