A corrosion-resistant aluminum alloy shell and a method for manufacturing the same
By magnetron sputtering a silver-titanium alloy layer onto the surface of an aluminum alloy shell and performing micro-arc oxidation treatment, combined with chemical plating of a Ni-WP lanthanum-infiltrated layer, the problems of insufficient corrosion resistance and hardness of the aluminum alloy shell were solved, achieving higher corrosion resistance and hardness.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DONGGUAN HUAHANG XINMA METAL CO LTD
- Filing Date
- 2026-06-22
- Publication Date
- 2026-07-31
AI Technical Summary
The existing aluminum alloy shell has high porosity and weak adhesion of the anodic oxide film, resulting in poor corrosion resistance. During the micro-arc oxidation process, the difference in thermal expansion coefficient between the film and the aluminum alloy shell causes stress concentration, which generates defects and affects corrosion resistance and hardness.
A silver-titanium alloy layer is magnetron sputtered onto the surface of an aluminum alloy shell. After micro-arc oxidation treatment, a Ni-WP lanthanum infiltrated layer is chemically plated. The difference in thermal expansion coefficient is mitigated by the silver-titanium alloy layer, forming a dense ceramic layer. Nano CeO2 particles and W elements are introduced into the micropores to improve chemical stability and hardness.
It significantly improves the corrosion resistance and hardness of the aluminum alloy shell, reduces film defects, and enhances the density and self-healing ability of the chemical plating layer.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of aluminum alloy technology, specifically to a corrosion-resistant aluminum alloy shell and its preparation method. Background Technology
[0002] Aluminum alloys are widely used in the protection of the shells of automobiles and marine equipment due to their low density and high strength. However, aluminum alloys are chemically active. Although a natural aluminum oxide film can be formed on the surface, the film has a limited thickness and a loose and porous structure, which limits its protective ability against the substrate. It is easily damaged by mechanical friction or corrosive media, causing the substrate to lose its protection and corrode rapidly.
[0003] Aluminum alloys are often treated with anodizing for corrosion resistance. This electrochemical oxidation process forms a thick aluminum oxide film on the surface of the casing, improving surface hardness and corrosion resistance. However, conventional anodized films still suffer from high porosity and weak adhesion, resulting in relatively weak corrosion resistance. Therefore, existing technologies often employ micro-arc oxidation. Compared to anodizing, which uses high-voltage plasma discharge to continuously increase the operating voltage to the critical voltage, this process involves localized high-temperature sintering to generate a thicker ceramic oxide film, achieving higher hardness, wear resistance, and corrosion resistance. However, due to differences in thermal expansion coefficients, defects can easily form between the film and the aluminum alloy casing, resulting in insufficient corrosion resistance and hardness.
[0004] In summary, solving the above problems and developing a corrosion-resistant aluminum alloy shell and its preparation method are of great significance. Summary of the Invention
[0005] The purpose of this invention is to provide a corrosion-resistant aluminum alloy shell and its preparation method, so as to solve the problems mentioned in the background art.
[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A method for preparing a corrosion-resistant aluminum alloy shell includes the following steps: S1: The surface of the aluminum alloy shell is successively polished, washed, and dried to obtain a pretreated aluminum alloy substrate; S2: A silver-titanium alloy layer is magnetron sputtered onto the surface of a pretreated aluminum alloy substrate to obtain a magnetron sputtered aluminum alloy. S3: Micro-arc oxidation treatment is performed on the surface of the magnetron sputtered aluminum alloy to obtain a micro-arc anodized aluminum alloy; S4: After sequential sensitization and activation on the surface of micro-arc aluminum alloy, a corrosion-resistant layer is chemically plated to obtain a corrosion-resistant aluminum alloy shell; In the magnetron sputtering process, the target material used is a silver-titanium alloy, and the mass ratio of silver to titanium is 1:4~9; The corrosion-resistant layer contains lanthanum.
[0007] Preferably, during the magnetron sputtering process, the working gas is argon, the working pressure is 0.6~1.2Pa, the magnetron sputtering current is 0.8~1.6A, the voltage is 300~450V, and the time is 30~70min.
[0008] Preferably, the chemical plating solution used in the chemical plating process includes the following raw materials: 0.5~1.5 g / L lanthanum nitrate, 0.2~1 g / L polyethylene glycol, 18~30 g / L nickel sulfate, 4~8 g / L sodium tungstate, 25~45 g / L sodium hypophosphite, 3~8 g / L sodium citrate, 12~15 g / L disodium ethylenediaminetetraacetate, 8~15 g / L sodium hydroxide, 3~6 g / L sodium fluoride, 0.001~0.003 g / L urea, with a pH of 9~12.
[0009] Preferably, the temperature during the chemical plating process is 50~70℃ and the time is 45~90min.
[0010] Preferably, the micro-arc oxidation electrolyte used in the micro-arc oxidation process includes the following raw materials: 1~2 g / L cerium dioxide, 1~2 g / L sodium tungstate, 12~20 g / L sodium silicate, 3~7 g / L potassium hydroxide, and 1~4 g / L sodium fluoride.
[0011] Preferably, in the micro-arc oxidation process, the stainless steel plate is used as the negative electrode, the magnetron sputtered aluminum alloy is used as the positive electrode, the temperature is 20~30℃, the duty cycle is 20~25%, and the current density is 5~10A / dm³. 2 The frequency is 500~1000Hz and the duration is 20~30min.
[0012] Preferably, the sensitizing solution used in the sensitization process includes the following raw materials: 8~10g / L stannous chloride and 25~30mL / L hydrochloric acid; the sensitization time is 3~8min.
[0013] Preferably, the activation solution used in the activation process includes the following raw materials: 8~10g / L silver nitrate; the activation time is 60~150s.
[0014] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: The present invention significantly improves the corrosion resistance and hardness of the aluminum alloy shell by sequentially magnetron sputtering a silver-titanium alloy layer on the surface of the aluminum alloy shell, followed by micro-arc oxidation treatment in a silicate electrolyte containing cerium oxide and sodium tungstate, and finally chemically plating a Ni-WP lanthanum infiltrated layer.
[0015] In the micro-arc oxidation process, sodium silicate is used as the main salt for film formation. Under the high-temperature sintering effect generated by high-voltage discharge, a ceramic layer containing α-Al2O3, γ-Al2O3, SiO2 and mullite phase is generated on the surface of aluminum alloy. This ceramic layer can serve as a hard and corrosion-resistant interface layer. By introducing cerium dioxide and sodium tungstate, nano-CeO2 particles can fill the discharge micropores of the micro-arc oxidation film, reduce film defects, and release Ce ions when the coating is damaged to generate a corrosion-inhibiting self-repairing effect. The addition of sodium tungstate introduces W element, which enhances the chemical stability and hardness of the film.
[0016] However, due to the significant difference in thermal expansion coefficients between the single micro-arc oxidation ceramic layer and the aluminum substrate, stress concentration and cracks inevitably occur, leading to reduced corrosion resistance. Therefore, this application further employs a magnetron sputtered silver-titanium alloy layer as an intermediate transition layer. During the micro-arc oxidation process, titanium can generate TiO2 or Al-Ti-O composite oxides to form a transition intermediate layer, alleviating the stress caused by the difference in thermal expansion coefficients. Meanwhile, silver is dispersed in elemental form within the pores and on the surface of the micro-arc oxidation layer, providing active deposition sites for subsequent electroless plating, improving the density of the electroless plating layer, and thus enhancing hardness and corrosion resistance.
[0017] Preferably, this application further electrolessly coats the surface of the micro-arc aluminum oxide alloy with a Ni-WP layer, which has excellent corrosion resistance and wear resistance. To further improve the hardness of the coating, this application also introduces lanthanum nitrate, which can react with Ni. 2+ The co-deposition of lanthanum into the Ni-WP coating refines the grains and improves the density of the coating. At the same time, the introduced polyethylene glycol not only improves wettability but also acts as a dispersant to stabilize La ions, promoting uniform co-deposition of lanthanum, improving the quality of the chemical coating, and thus enhancing corrosion resistance.
[0018] However, it should be noted that the subsequent activation process time needs to be limited to 60~150s. This is because the micro-arc oxidation layer of this application already contains a certain amount of elemental silver inside the pores, which can serve as deposition sites. When the activation time continues to increase, it may cause silver to agglomerate in the micropores, causing pore blockage, and may also cause the ceramic layer to become loose, resulting in void defects, which reduces hardness and corrosion resistance. Detailed Implementation
[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0020] Example 1: A method for preparing a corrosion-resistant aluminum alloy shell includes the following steps: S1: After polishing the surface of the aluminum alloy shell with 600~1500 grit sandpaper, wash it with deionized water and anhydrous ethanol respectively, and dry it to obtain the pretreated aluminum alloy substrate. S2: Fix the pretreated aluminum alloy substrate on the sample stage, using a silver-titanium alloy target with a mass ratio of 1:6 as the target material, and evacuate to 6×10⁻⁶. -4 Pa, high-purity argon gas was introduced, the working gas pressure was adjusted to 0.8 Pa, the sputtering current was controlled to 1.1 A, the voltage was 300 V, and the magnetron sputtering treatment was carried out for 60 min to obtain magnetron sputtered aluminum alloy; S3: Prepare a micro-arc oxidation electrolyte with raw materials of 1.6 g / L cerium dioxide, 1.4 g / L sodium tungstate, 15 g / L sodium silicate, 6 g / L potassium hydroxide, and 3 g / L sodium fluoride; suspend the magnetron sputtered aluminum alloy in the micro-arc oxidation electrolyte, using a stainless steel plate as the negative electrode and the magnetron sputtered aluminum alloy as the positive electrode, at a temperature of 25℃, a duty cycle of 20%, and a current density of 5 A / dm³. 2 The micro-arc oxidation process was performed at a frequency of 500 Hz for 25 min, followed by sealing with deionized water at 90 ℃ for 5 min to obtain a micro-arc oxidized aluminum alloy. S4: Prepare a sensitizing solution with 10 g / L stannous chloride and 30 mL / L hydrochloric acid; an activation solution with 8 g / L silver nitrate; and a chemical plating solution with 1.2 g / L lanthanum nitrate, 0.6 g / L polyethylene glycol, 25 g / L nickel sulfate, 7 g / L sodium tungstate, 30 g / L sodium hypophosphite, 5 g / L sodium citrate, 15 g / L disodium ethylenediaminetetraacetate, 12 g / L sodium hydroxide, 4 g / L sodium fluoride, and 0.002 g / L urea. Sensitize the micro-arc aluminum alloy with the sensitizing solution for 5 min, then activate it with the activation solution for 120 s. Finally, suspend the micro-arc aluminum alloy in the chemical plating solution and chemically platrude it at 60°C for 55 min to obtain a corrosion-resistant aluminum alloy shell.
[0021] Example 2: A method for preparing a corrosion-resistant aluminum alloy shell includes the following steps: S1: After polishing the surface of the aluminum alloy shell with 600~1500 grit sandpaper, wash it with deionized water and anhydrous ethanol respectively, and dry it to obtain the pretreated aluminum alloy substrate. S2: Fix the pretreated aluminum alloy substrate on the sample stage, using a silver-titanium alloy target with a mass ratio of 1:6 as the target material, and evacuate to 6×10⁻⁶. -4 Pa, high-purity argon gas was introduced, the working gas pressure was adjusted to 0.8 Pa, the sputtering current was controlled to 1.1 A, the voltage was 300 V, and the magnetron sputtering treatment was carried out for 35 min to obtain magnetron sputtered aluminum alloy; S3: Prepare a micro-arc oxidation electrolyte with raw materials of 1.6 g / L cerium dioxide, 1.4 g / L sodium tungstate, 15 g / L sodium silicate, 6 g / L potassium hydroxide, and 3 g / L sodium fluoride; suspend the magnetron sputtered aluminum alloy in the micro-arc oxidation electrolyte, using a stainless steel plate as the negative electrode and the magnetron sputtered aluminum alloy as the positive electrode, at a temperature of 25℃, a duty cycle of 20%, and a current density of 5 A / dm³. 2 The micro-arc oxidation process was performed at a frequency of 500 Hz for 25 min, followed by sealing with deionized water at 90 ℃ for 5 min to obtain a micro-arc oxidized aluminum alloy. S4: Prepare a sensitizing solution with 10 g / L stannous chloride and 30 mL / L hydrochloric acid; an activation solution with 8 g / L silver nitrate; and a chemical plating solution with 1.2 g / L lanthanum nitrate, 0.6 g / L polyethylene glycol, 25 g / L nickel sulfate, 7 g / L sodium tungstate, 30 g / L sodium hypophosphite, 5 g / L sodium citrate, 15 g / L disodium ethylenediaminetetraacetate, 12 g / L sodium hydroxide, 4 g / L sodium fluoride, and 0.002 g / L urea. Sensitize the micro-arc aluminum alloy with the sensitizing solution for 7 min, then activate it with the activation solution for 90 s. Finally, suspend the micro-arc aluminum alloy in the chemical plating solution and chemically platrude it at 65°C for 80 min to obtain a corrosion-resistant aluminum alloy shell.
[0022] Example 3: A method for preparing a corrosion-resistant aluminum alloy shell includes the following steps: S1: After polishing the surface of the aluminum alloy shell with 600~1500 grit sandpaper, wash it with deionized water and anhydrous ethanol respectively, and dry it to obtain the pretreated aluminum alloy substrate. S2: Fix the pretreated aluminum alloy substrate on the sample stage, using a silver-titanium alloy target with a mass ratio of 1:6 as the target material, and evacuate to 6×10⁻⁶. -4 Pa, high-purity argon gas was introduced, the working gas pressure was adjusted to 0.8 Pa, the sputtering current was controlled to 1.1 A, the voltage was 300 V, and the magnetron sputtering treatment was carried out for 65 min to obtain magnetron sputtered aluminum alloy; S3: Prepare a micro-arc oxidation electrolyte with raw materials of 1.6 g / L cerium dioxide, 1.4 g / L sodium tungstate, 15 g / L sodium silicate, 6 g / L potassium hydroxide, and 3 g / L sodium fluoride; suspend the magnetron sputtered aluminum alloy in the micro-arc oxidation electrolyte, using a stainless steel plate as the negative electrode and the magnetron sputtered aluminum alloy as the positive electrode, at a temperature of 25℃, a duty cycle of 20%, and a current density of 5 A / dm³. 2 The micro-arc oxidation process was performed at a frequency of 500 Hz for 25 min, followed by sealing with deionized water at 90 ℃ for 5 min to obtain a micro-arc oxidized aluminum alloy. S4: Prepare a sensitizing solution with raw materials of 10 g / L stannous chloride and 30 mL / L hydrochloric acid; an activation solution with raw materials of 8 g / L silver nitrate; and a chemical plating solution with raw materials of 1.2 g / L lanthanum nitrate, 0.6 g / L polyethylene glycol, 25 g / L nickel sulfate, 7 g / L sodium tungstate, 30 g / L sodium hypophosphite, 5 g / L sodium citrate, 15 g / L disodium ethylenediaminetetraacetate, 12 g / L sodium hydroxide, 4 g / L sodium fluoride, and 0.002 g / L urea. Sensitize the micro-arc aluminum alloy with the sensitizing solution for 4 min, then activate it with the activation solution for 150 s. Finally, suspend the micro-arc aluminum alloy in the chemical plating solution and chemically plating it at 55℃ for 70 min to obtain a corrosion-resistant aluminum alloy shell.
[0023] Comparative Example 1: Based on Example 1, silver-titanium alloy was sputtered without magnetron sputtering, and the remaining processes were the same as in Example 1, specifically including the following steps: S1: After polishing the surface of the aluminum alloy shell with 600~1500 grit sandpaper, wash it with deionized water and anhydrous ethanol respectively, and dry it to obtain the pretreated aluminum alloy substrate. S2: Prepare a micro-arc oxidation electrolyte with raw materials of 1.6 g / L cerium dioxide, 1.4 g / L sodium tungstate, 15 g / L sodium silicate, 6 g / L potassium hydroxide, and 3 g / L sodium fluoride; suspend the pretreated aluminum alloy substrate in the micro-arc oxidation electrolyte, using a stainless steel plate as the negative electrode and the pretreated aluminum alloy substrate as the positive electrode, at a temperature of 25℃, a duty cycle of 20%, and a current density of 5 A / dm³. 2 The micro-arc oxidation process was performed at a frequency of 500 Hz for 25 min, followed by sealing with deionized water at 90 ℃ for 5 min to obtain a micro-arc oxidized aluminum alloy. S3: Prepare a sensitizing solution with raw materials of 10 g / L stannous chloride and 30 mL / L hydrochloric acid; an activation solution with raw materials of 8 g / L silver nitrate; and a chemical plating solution with raw materials of 1.2 g / L lanthanum nitrate, 0.6 g / L polyethylene glycol, 25 g / L nickel sulfate, 7 g / L sodium tungstate, 30 g / L sodium hypophosphite, 5 g / L sodium citrate, 15 g / L disodium ethylenediaminetetraacetate, 12 g / L sodium hydroxide, 4 g / L sodium fluoride, and 0.002 g / L urea. Sensitize the micro-arc aluminum alloy with the sensitizing solution for 5 min, then activate it with the activation solution for 120 s. Finally, suspend the micro-arc aluminum alloy in the chemical plating solution and chemically plating it at 60℃ for 55 min to obtain a corrosion-resistant aluminum alloy shell.
[0024] Comparative Example 2: Based on Example 1, pure titanium was used as the target material for sputtering, and the remaining processes were the same as in Example 1, specifically including the following steps: S1: After polishing the surface of the aluminum alloy shell with 600~1500 grit sandpaper, wash it with deionized water and anhydrous ethanol respectively, and dry it to obtain the pretreated aluminum alloy substrate. S2: Fix the pretreated aluminum alloy substrate onto the sample stage, using a pure titanium target as the target material, and evacuate to 6×10⁻⁶. -4 Pa, high-purity argon gas was introduced, the working gas pressure was adjusted to 0.8 Pa, the sputtering current was controlled to 1.1 A, the voltage was 300 V, and the magnetron sputtering treatment was carried out for 60 min to obtain magnetron sputtered aluminum alloy; S3: Prepare a micro-arc oxidation electrolyte with raw materials of 1.6 g / L cerium dioxide, 1.4 g / L sodium tungstate, 15 g / L sodium silicate, 6 g / L potassium hydroxide, and 3 g / L sodium fluoride; suspend the magnetron sputtered aluminum alloy in the micro-arc oxidation electrolyte, using a stainless steel plate as the negative electrode and the magnetron sputtered aluminum alloy as the positive electrode, at a temperature of 25℃, a duty cycle of 20%, and a current density of 5 A / dm³. 2 The micro-arc oxidation process was performed at a frequency of 500 Hz for 25 min, followed by sealing with deionized water at 90 ℃ for 5 min to obtain a micro-arc oxidized aluminum alloy. S4: Prepare a sensitizing solution with 10 g / L stannous chloride and 30 mL / L hydrochloric acid; an activation solution with 8 g / L silver nitrate; and a chemical plating solution with 1.2 g / L lanthanum nitrate, 0.6 g / L polyethylene glycol, 25 g / L nickel sulfate, 7 g / L sodium tungstate, 30 g / L sodium hypophosphite, 5 g / L sodium citrate, 15 g / L disodium ethylenediaminetetraacetate, 12 g / L sodium hydroxide, 4 g / L sodium fluoride, and 0.002 g / L urea. Sensitize the micro-arc aluminum alloy with the sensitizing solution for 5 min, then activate it with the activation solution for 120 s. Finally, suspend the micro-arc aluminum alloy in the chemical plating solution and chemically platrude it at 60°C for 55 min to obtain a corrosion-resistant aluminum alloy shell.
[0025] Comparative Example 3: Based on Example 1, without the addition of polyethylene glycol, the remaining processes are the same as in Example 1, specifically including the following steps: S1: After polishing the surface of the aluminum alloy shell with 600~1500 grit sandpaper, wash it with deionized water and anhydrous ethanol respectively, and dry it to obtain the pretreated aluminum alloy substrate. S2: Fix the pretreated aluminum alloy substrate on the sample stage, using a silver-titanium alloy target with a mass ratio of 1:6 as the target material, and evacuate to 6×10⁻⁶. -4 Pa, high-purity argon gas was introduced, the working gas pressure was adjusted to 0.8 Pa, the sputtering current was controlled to 1.1 A, the voltage was 300 V, and the magnetron sputtering treatment was carried out for 60 min to obtain magnetron sputtered aluminum alloy; S3: Prepare a micro-arc oxidation electrolyte with raw materials of 1.6 g / L cerium dioxide, 1.4 g / L sodium tungstate, 15 g / L sodium silicate, 6 g / L potassium hydroxide, and 3 g / L sodium fluoride; suspend the magnetron sputtered aluminum alloy in the micro-arc oxidation electrolyte, using a stainless steel plate as the negative electrode and the magnetron sputtered aluminum alloy as the positive electrode, at a temperature of 25℃, a duty cycle of 20%, and a current density of 5 A / dm³.2 The micro-arc oxidation process was performed at a frequency of 500 Hz for 25 min, followed by sealing with deionized water at 90 ℃ for 5 min to obtain a micro-arc oxidized aluminum alloy. S4: Prepare a sensitizing solution with 10 g / L stannous chloride and 30 mL / L hydrochloric acid; an activation solution with 8 g / L silver nitrate; and a chemical plating solution with 1.2 g / L lanthanum nitrate, 25 g / L nickel sulfate, 7 g / L sodium tungstate, 30 g / L sodium hypophosphite, 5 g / L sodium citrate, 15 g / L disodium ethylenediaminetetraacetate, 12 g / L sodium hydroxide, 4 g / L sodium fluoride, and 0.002 g / L urea. Sensitize the micro-arc aluminum alloy with the sensitizing solution for 5 min, then activate it with the activation solution for 120 s. Finally, suspend the micro-arc aluminum alloy in the chemical plating solution and chemically platrude it at 60°C for 55 min to obtain a corrosion-resistant aluminum alloy shell.
[0026] Comparative Example 4: Based on Example 1, the activation treatment time was increased, while the remaining processes were the same as in Example 1, specifically including the following steps: S1: After polishing the surface of the aluminum alloy shell with 600~1500 grit sandpaper, wash it with deionized water and anhydrous ethanol respectively, and dry it to obtain the pretreated aluminum alloy substrate. S2: Fix the pretreated aluminum alloy substrate on the sample stage, using a silver-titanium alloy target with a mass ratio of 1:6 as the target material, and evacuate to 6×10⁻⁶. -4 Pa, high-purity argon gas was introduced, the working gas pressure was adjusted to 0.8 Pa, the sputtering current was controlled to 1.1 A, the voltage was 300 V, and the magnetron sputtering treatment was carried out for 60 min to obtain magnetron sputtered aluminum alloy; S3: Prepare a micro-arc oxidation electrolyte with raw materials of 1.6 g / L cerium dioxide, 1.4 g / L sodium tungstate, 15 g / L sodium silicate, 6 g / L potassium hydroxide, and 3 g / L sodium fluoride; suspend the magnetron sputtered aluminum alloy in the micro-arc oxidation electrolyte, using a stainless steel plate as the negative electrode and the magnetron sputtered aluminum alloy as the positive electrode, at a temperature of 25℃, a duty cycle of 20%, and a current density of 5 A / dm³. 2 The micro-arc oxidation process was performed at a frequency of 500 Hz for 25 min, followed by sealing with deionized water at 90 ℃ for 5 min to obtain a micro-arc oxidized aluminum alloy. S4: Prepare a sensitizing solution with 10 g / L stannous chloride and 30 mL / L hydrochloric acid; an activation solution with 8 g / L silver nitrate; and a chemical plating solution with 1.2 g / L lanthanum nitrate, 0.6 g / L polyethylene glycol, 25 g / L nickel sulfate, 7 g / L sodium tungstate, 30 g / L sodium hypophosphite, 5 g / L sodium citrate, 15 g / L disodium ethylenediaminetetraacetate, 12 g / L sodium hydroxide, 4 g / L sodium fluoride, and 0.002 g / L urea. Sensitize the micro-arc aluminum alloy with the sensitizing solution for 5 min, then activate it with the activation solution for 240 s. Finally, suspend the micro-arc aluminum alloy in the chemical plating solution and chemically platrude it at 60°C for 55 min to obtain a corrosion-resistant aluminum alloy shell.
[0027] It should be noted that the raw materials involved in the above process are not subject to any special restrictions and include, for example: aluminum alloy shell, model AL6061-T6; cerium dioxide, particle size 20~50nm; sodium tungstate, Na2WO4·2H2O; sodium silicate, Na2SiO3·9H2O; stannous chloride, SnCl2·2H2O; lanthanum nitrate, La(NO3)3·6H2O; polyethylene glycol, molecular weight 400; nickel sulfate, NiSO4·6H2O; sodium hypophosphite, NaH2PO2·H2O; sodium citrate, Na3C6H5O7·2H2O; all raw materials are commercially available.
[0028] Performance testing: (1) Simulated seawater corrosion solution was prepared according to ASTM D1141-98. A three-electrode system was used, with the samples prepared in each example and comparative example as the working electrode, the calomel electrode as the reference electrode, and the platinum electrode as the auxiliary electrode. The voltage range was -0.3~0.3V, the scan rate was 1mV / s, and the corrosion current density was measured. The exposed area of the sample was 1cm². 2 ; (2) The microhardness of the samples prepared in the examples and comparative examples was measured using a Vickers hardness tester. The load was 100g and the loading time was 10 seconds. The experimental data are shown in the table below.
[0029]
[0030] As shown in the table, Comparative Example 1, without magnetron sputtering of silver-titanium alloy, lacks a corrosion-resistant interface layer, is prone to stress and defects, and exhibits decreased corrosion resistance and hardness. Comparative Example 2 uses pure titanium as the target material for sputtering. The introduction of titanium alleviates the stress concentration caused by the coefficient of thermal expansion, resulting in significantly better corrosion resistance than Comparative Example 1. However, its hardness is not as good as that of Example 1, indicating that the silver introduced by magnetron sputtering can promote the uniformity and density of subsequent chemical coating deposition. In Comparative Example 3, the absence of polyethylene glycol makes it difficult to penetrate to the bottom of the pores, resulting in defects and decreased uniformity and density of the chemical coating, leading to a decrease in corrosion resistance and hardness. In Comparative Example 4, the activation treatment time was increased, causing excessive agglomeration of silver particles at the micropore openings, blocking the pores and resulting in defects in the chemical coating, decreased corrosion resistance, and a slight decrease in hardness.
[0031] In summary, the aluminum alloy shell prepared in this application has excellent corrosion resistance and good hardness.
[0032] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing a corrosion-resistant aluminum alloy shell, characterized in that: Includes the following steps: S1: The surface of the aluminum alloy shell is successively polished, washed, and dried to obtain a pretreated aluminum alloy substrate; S2: A silver-titanium alloy layer is magnetron sputtered onto the surface of a pretreated aluminum alloy substrate to obtain a magnetron sputtered aluminum alloy. S3: Micro-arc oxidation treatment is performed on the surface of the magnetron sputtered aluminum alloy to obtain a micro-arc anodized aluminum alloy; S4: After sequential sensitization and activation on the surface of micro-arc aluminum alloy, a corrosion-resistant layer is chemically plated to obtain a corrosion-resistant aluminum alloy shell; In the magnetron sputtering process, the target material used is a silver-titanium alloy, and the mass ratio of silver to titanium is 1:4~9; The corrosion-resistant layer contains lanthanum.
2. The method for preparing a corrosion-resistant aluminum alloy shell according to claim 1, characterized in that: During the magnetron sputtering process, the working gas is argon, the working pressure is 0.6~1.2Pa, the magnetron sputtering current is 0.8~1.6A, the voltage is 300~450V, and the time is 30~70min.
3. The method for preparing a corrosion-resistant aluminum alloy shell according to claim 1, characterized in that: The chemical plating process uses a chemical plating solution comprising the following raw materials: 0.5-1.5 g / L lanthanum nitrate, 0.2-1 g / L polyethylene glycol, 18-30 g / L nickel sulfate, 4-8 g / L sodium tungstate, 25-45 g / L sodium hypophosphite, 3-8 g / L sodium citrate, 12-15 g / L disodium ethylenediaminetetraacetate, 8-15 g / L sodium hydroxide, 3-6 g / L sodium fluoride, and 0.001-0.003 g / L urea, with a pH of 9-12.
4. The method for preparing a corrosion-resistant aluminum alloy shell according to claim 1, characterized in that: During the chemical plating process, the temperature is 50~70℃ and the time is 45~90min.
5. The method for preparing a corrosion-resistant aluminum alloy shell according to claim 1, characterized in that: The micro-arc oxidation electrolyte used in the process includes the following raw materials: 1~2g / L cerium dioxide, 1~2g / L sodium tungstate, 12~20g / L sodium silicate, 3~7g / L potassium hydroxide, and 1~4g / L sodium fluoride.
6. The method for preparing a corrosion-resistant aluminum alloy shell according to claim 1, characterized in that: During the micro-arc oxidation process, a stainless steel plate is used as the negative electrode, and a magnetron sputtered aluminum alloy is used as the positive electrode. The temperature is 20~30℃, the duty cycle is 20~25%, and the current density is 5~10A / dm². 2 The frequency is 500~1000Hz and the duration is 20~30min.
7. The method for preparing a corrosion-resistant aluminum alloy shell according to claim 1, characterized in that: The sensitization process uses a sensitizing solution comprising the following ingredients: 8-10 g / L stannous chloride and 25-30 mL / L hydrochloric acid; the sensitization time is 3-8 min.
8. The method for preparing a corrosion-resistant aluminum alloy shell according to claim 1, characterized in that: The activation solution used in the activation process includes the following raw materials: 8~10g / L silver nitrate; the activation time is 60~150s.
9. A corrosion-resistant aluminum alloy shell prepared by the method for preparing a corrosion-resistant aluminum alloy shell according to any one of claims 1 to 8.