Preparation method of super-hydrophobic aluminum profile and application thereof in marine environment

Abstract

The application discloses a preparation method of super-hydrophobic aluminum profiles and application thereof in marine environment and belongs to the technical field of aluminum alloy materials. Firstly, alloy elements are optimized in the application, and secondly, in a key process step, i.e., an anodic oxidation, an anode electrolyte composition is optimized, and a basic electrolyte and a modified additive are arranged. A polyethylene glycol-titanium potassium oxalate-citric acid ternary composite additive is adopted, a double-voltage gradient oxidation process is combined, a multistage composite structure is constructed in an oxidation film, and an aluminum alloy profile with high hardness (>=500HV) and stable super-hydrophobicity (a contact angle >=160 DEG) is realized. The super-hydrophobic aluminum profile prepared by the method has strong corrosion resistance and still maintains excellent performance in an extreme environment, remarkably prolongs the service life of equipment, and improves the safety and stability of offshore facilities.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy material technology, specifically relating to a method for preparing superhydrophobic aluminum profiles and their application in marine environments. Background Technology

[0002] Aluminum is relatively abundant and possesses advantages such as low density, good thermal and electrical conductivity, high strength, good corrosion resistance, and good machinability. It has wide applications in aerospace, shipbuilding, machinery, and instrumentation industries, and is one of the main materials chosen for lightweight structural design. In atmospheric environments, pure aluminum materials naturally form a self-healing oxide film on their surface, providing good corrosion resistance. To improve the strength of aluminum, it is alloyed. Cast aluminum alloys mainly include Al-Si, Al-Cu, Al-Mg, and Al-Zn systems. Among them, Al-Si aluminum alloys have better casting performance but relatively poorer corrosion resistance. The marine environment is harsh and complex, and the safety of various equipment operating in this environment is of great concern. In marine environments, aluminum profiles face long-term challenges such as chloride ion corrosion, microbial adhesion, and ultraviolet aging.

[0003] Traditional superhydrophobic surfaces rely on chemical plating or fluorination, which suffers from drawbacks such as complex processes, high environmental toxicity, and poor durability. For example, Chinese patent application CN202010567890.X discloses a method for surface treatment of aluminum alloys, comprising the following steps: pretreating the aluminum alloy surface; placing the pretreated aluminum alloy in a chemical polishing solution for chemical polishing, the chemical polishing solution comprising the following components by mass fraction: phosphoric acid: 55%-75%; sulfuric acid: 15%-30%; polyethylene glycol: 10%-25%; copper sulfate: 2%-5%; and anodizing the chemically polished aluminum alloy. This aluminum alloy surface treatment method reduces the need for traditional alkaline etching and, by adding copper sulfate and polyethylene glycol to the chemical polishing solution to increase its viscosity, reduces corrosion of the aluminum alloy.

[0004] For example, Chinese patent application CN202311056501.7 discloses a surface treatment method for aluminum alloys. The method involves grinding, polishing, cleaning, and etching the surface of the aluminum alloy, immersing the aluminum alloy in a silane coupling agent solution, removing it, and then heating and curing it. This generates a superhydrophobic film layer with micro-nano structure in situ on the surface of the aluminum alloy. Due to the micro-nano composite rough structure of the surface coating, the aluminum alloy treated by this method exhibits superhydrophobic and corrosion-resistant properties.

[0005] Therefore, with current technologies, these coatings are prone to peeling off, and the construction of micro- and nano-structures mostly relies on chemical etching or template methods, making it difficult to precisely control the morphology. Therefore, it is necessary to develop a method for preparing superhydrophobic aluminum profiles that combines high mechanical stability, environmental friendliness, and high durability. Summary of the Invention

[0006] This invention addresses the problems existing in the prior art by developing a polyethylene glycol-potassium titanium oxalate-citric acid ternary composite additive and combining it with a dual-voltage gradient oxidation process to construct a multi-level composite structure in the oxide film. This simultaneously achieves the construction of aluminum alloy profiles with high hardness (≥500HV) and stable superhydrophobicity (contact angle ≥160°), making it particularly suitable for marine environments. It effectively resists chloride ion corrosion, microbial adhesion, and ultraviolet aging, significantly improving equipment safety and service life.

[0007] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a superhydrophobic aluminum profile includes the following preparation steps:

[0009] (1) Batching and smelting: Batching is carried out according to the following mass percentages: Cu 3-8%, Fe 2-5%, Mn 5-9%, Mg 1-2%, Zn 1-2%, Si 0.5-0.8%, Ni 0.1%, Ti 0.05%, Zr 0.05-0.1%, Y 0.02-0.05%, Sc 0.01-0.03%, with the remainder being Al and unavoidable impurities. The total amount of unavoidable impurities is ≤0.1%. The mixture is smelted at high temperature for 6-8 hours to obtain aluminum alloy melt; after refining and casting, a cast rod is obtained.

[0010] (2) The cast rod obtained in step (1) is placed in a homogenizing furnace and heated to 480-550℃ for 10-15 hours. After the homogenization treatment is completed, it is cooled. The cast rod is then extruded and aged to obtain aluminum alloy profiles.

[0011] (3) Immerse the aluminum alloy profile in an alkaline degreasing solution at 55-60℃ for 3-5 minutes to remove oil stains, take it out, and wash it with water;

[0012] (4) Then immerse it in an acidic solution at 50-55℃ for 30-40 seconds to improve the surface smoothness;

[0013] (5) Anodizing treatment: The aluminum alloy substrate treated in step (4) is anodized in an electrolyte, with the aluminum alloy as the anode and the aluminum plate as the cathode. The oxidation voltage is 15-20V and the current density is 1-2A / dm³. 2 The electrolyte temperature is 10-20℃, and the oxidation time is 20-40 minutes; then the voltage is increased to 80-100V, and the oxidation time is 20-30 minutes. Air stirring is used during the anodizing process.

[0014] (6) Post-treatment: After anodizing, the profile is treated with hot air at 100-120℃ for 30 minutes; then the treated aluminum alloy substrate is immersed in passivation solution at 80-85℃ for 15-30 minutes, taken out and drained of surface moisture, and dried at 80-90℃ for 2-4 hours to obtain the preparation method of superhydrophobic aluminum profile.

[0015] Furthermore, in step (2) aging treatment, the aging temperature is 165-175℃ and the aging treatment time is 10-12h.

[0016] Furthermore, the composition of the alkaline degreasing solution in step (3) is: 50g / L NaOH, 20g / L Na3PO4, and water as the solvent.

[0017] Furthermore, in step (4), the acidic solution is a mixture of phosphoric acid and nitric acid, with a mass concentration of 70% for phosphoric acid and a mass concentration of 30% for nitric acid, which are obtained by mixing them in a volume ratio of 1:1.

[0018] Furthermore, in step (5), the electrolyte comprises a base electrode solution and a modified additive, wherein the base electrode solution comprises oxalic acid, phosphoric acid and sulfuric acid, with an oxalic acid concentration of 40 g / L, a phosphoric acid concentration of 20 g / L and a sulfuric acid concentration of 5 g / L; the modified additive comprises polyethylene glycol, potassium titanium oxalate and citric acid, with a polyethylene glycol concentration of 10 g / L, a potassium titanium oxalate concentration of 10 g / L and a citric acid concentration of 10 g / L.

[0019] Furthermore, the passivation solution in step (6) consists of chromic anhydride, sodium fluoride and water, with a chromic anhydride concentration of 200 g / L, a sodium fluoride concentration of 20 g / L and water as the solvent.

[0020] A method for preparing superhydrophobic aluminum profiles is disclosed. The aluminum alloy profiles prepared by this method are processed according to actual needs and applied to deep-sea equipment and offshore wind power facilities.

[0021] Beneficial effects:

[0022] (1) First, the alloy elements of this invention are optimized. The main elements work together: core metal elements such as Cu (3-8%) and Mn (5-9%) form Al2CuMg and Al6Mn strengthening phases to improve strength; Fe (2-5%) refines grains, and Mg and Zn enhance the age hardening effect; the addition of Zr and Sc forms nano-Al3(Sc,Zr) dispersed phases, which inhibit recrystallization and improve high-temperature stability; the Si content is controlled to avoid coarse silicon phases, and the total amount of impurities ≤0.1% can effectively prevent grain boundary segregation.

[0023] (2) In the key process step of anodizing, the composition of the anolyte was optimized, and a base electrolyte and modifying additives were set. In the base electrolyte, oxalic acid promotes the growth of porous layers, phosphoric acid expands pores, and sulfuric acid enhances reaction activity. At the same time, the modifying additives were added, and the three worked synergistically to improve the corrosion resistance of the material. Polyethylene glycol (PEG1000): as a surfactant, it reduces the surface tension of the electrolyte, promotes the penetration of the electrolyte in the micropores, and inhibits film defects caused by bubble retention; potassium titanium oxalate releases TiO2 during the anodizing process. 2+ By driving the embedding of the film into the alumina lattice with an electric field, Ti-O-Al bonds are formed, thereby improving the microhardness of the film; while citric acid and Al 3+ The formation of a stable complex ([Al(C6H5O7)]⁻) slows down the alumina deposition rate and induces the directional growth of micropores. Simultaneously, the carboxylic acid groups carbonize during the hot air post-treatment stage, generating hydrophobic carbon chains (-CH2-), further enhancing the superhydrophobic properties of the profile surface. Moreover, the three components exhibit the best effect under equal concentration conditions.

[0024] (3) Simultaneously, dual voltage gradient oxidation is adopted. The first stage (15-20V): low voltage generates a dense barrier layer (thickness of about 2-3μm) to reduce the active dissolution of the matrix Al; the second stage (80-100V): high voltage induces "electric breakdown effect" to epitaxially grow a multi-level microporous structure on the dense layer (increasing the specific surface area).

[0025] (4) Finally, the passivation solution is used for sealing. Chromic anhydride (200g / L) and sodium fluoride (20g / L) work together to form a Cr-OF-Al passivation film to fill the microcracks in the oxide layer.

[0026] (5) The superhydrophobic aluminum profiles prepared by this method are not only highly corrosion resistant, but also maintain excellent performance in extreme environments, significantly extending the service life of equipment and improving the safety and stability of offshore facilities. Attached Figure Description

[0027] Figure 1 The microstructure and energy dispersive spectroscopy (EDS) analysis of the aluminum alloy in simulated seawater after 2000 hours of experimentation in Example 1 of this invention are shown in (a) for the aluminum alloy before corrosion, (b) for the aluminum alloy after corrosion, and (c) for the EDS analysis of the corroded surface. Detailed Implementation

[0028] The technical solution of the present invention will be further described below with reference to specific embodiments, but it is not limited thereto.

[0029] Example 1

[0030] A method for preparing a superhydrophobic aluminum profile includes the following preparation steps:

[0031] (1) Batching and smelting: Batching is carried out according to the following mass percentages: Cu 3%, Fe 2%, Mn 5%, Mg 1%, Zn 1%, Si 0.5%, Ni 0.1%, Ti 0.05%, Zr 0.1%, Y 0.05%, Sc 0.03%, with the remainder being Al and unavoidable impurities. The total amount of unavoidable impurities is ≤0.1%. The mixture is smelted at high temperature for 6-8 hours to obtain aluminum alloy melt; then refined and cast to obtain cast rods.

[0032] (2) The casting rod obtained in step (1) is placed in a homogenizing furnace and heated to 480°C for 10 hours. After the homogenization treatment is completed, it is cooled. The casting rod is then extruded and aged to obtain aluminum alloy profiles.

[0033] (3) Immerse the aluminum alloy profile in an alkaline degreasing solution at 55-60℃ for 3 minutes to remove oil stains, take it out, and wash it with water.

[0034] (4) Then immerse it in an acidic solution at 50-55℃ for 30 seconds to improve the surface smoothness;

[0035] (5) Anodizing treatment: The aluminum alloy substrate treated in step (4) is anodized in an electrolyte, with the aluminum alloy as the anode and the aluminum plate as the cathode. The oxidation voltage is 15V and the current density is 1A / dm³. 2 The electrolyte temperature is 10-20℃, and the oxidation time is 20 minutes; then the voltage is increased to 80V, and the oxidation is carried out for 20 minutes. Air stirring is used during the anodizing process.

[0036] (6) Post-treatment: The anodized profile is treated with hot air at 100-120℃ for 30 minutes; then the treated aluminum alloy substrate is immersed in passivation solution at 80-85℃ for 15 minutes, taken out and drained of surface moisture, and dried at 80-90℃ for 2 hours to obtain the preparation method of superhydrophobic aluminum profile.

[0037] In step (2), the aging temperature is 165-175℃ and the aging time is 10h.

[0038] The alkaline degreasing solution in step (3) consists of 50 g / L NaOH, 20 g / L Na3PO4, and water as the solvent.

[0039] Step (4) The acidic solution is a mixture of phosphoric acid and nitric acid, with a mass concentration of 70% for phosphoric acid and 30% for nitric acid. The two are mixed in a volume ratio of 1:1.

[0040] Step (5) The electrolyte contains a base electrode solution and a modifying additive. The base electrode solution contains oxalic acid, phosphoric acid and sulfuric acid, with a concentration of 40 g / L for oxalic acid, 20 g / L for phosphoric acid and 5 g / L for sulfuric acid. The modifying additive contains polyethylene glycol, potassium titanium oxalate and citric acid, with a concentration of 10 g / L for polyethylene glycol, 10 g / L for potassium titanium oxalate and 10 g / L for citric acid.

[0041] Step (6) The passivation solution consists of chromic anhydride, sodium fluoride and water. The concentration of chromic anhydride is 200 g / L, the concentration of sodium fluoride is 20 g / L, and the solvent is water.

[0042] Example 2

[0043] A method for preparing a superhydrophobic aluminum profile includes the following preparation steps:

[0044] (1) Batching and smelting: Batching is carried out according to the following mass percentages: Cu 5%, Fe 3%, Mn 7%, Mg 2%, Zn 2%, Si 0.6%, Ni 0.1%, Ti 0.05%, Zr 0.1%, Y 0.02%, Sc 0.01%, with the remainder being Al and unavoidable impurities. The total amount of unavoidable impurities is ≤0.1%. The mixture is smelted at high temperature for 6-8 hours to obtain aluminum alloy melt; then refined and cast to obtain cast rods.

[0045] (2) The cast rod obtained in step (1) is placed in a homogenizing furnace and heated to 500°C for 12 hours. After the homogenization treatment is completed, it is cooled. The cast rod is then extruded and aged to obtain aluminum alloy profiles.

[0046] (3) Immerse the aluminum alloy profile in an alkaline degreasing solution at 55-60℃ for 3 minutes to remove oil stains, take it out, and wash it with water.

[0047] (4) Then immerse it in an acidic solution at 50-55℃ for 30 seconds to improve the surface smoothness;

[0048] (5) Anodizing treatment: The aluminum alloy substrate treated in step (4) is anodized in an electrolyte, with the aluminum alloy as the anode and the aluminum plate as the cathode. The oxidation voltage is 20V and the current density is 1A / dm³. 2 The electrolyte temperature is 10-20℃, and the oxidation time is 30 minutes; then the voltage is increased to 90V, and the oxidation time is 25 minutes. Air stirring is used during the anodizing process.

[0049] (6) Post-treatment: The anodized profile is treated with hot air at 100-120℃ for 30 minutes; then the treated aluminum alloy substrate is immersed in passivation solution at 80-85℃ for 20 minutes, taken out and drained of surface moisture, and dried at 80-90℃ for 3 hours to obtain the preparation method of superhydrophobic aluminum profile.

[0050] In step (2), the aging temperature is 165-175℃ and the aging time is 11h.

[0051] The alkaline degreasing solution in step (3) consists of 50 g / L NaOH, 20 g / L Na3PO4, and water as the solvent.

[0052] Step (4) The acidic solution is a mixture of phosphoric acid and nitric acid, with a mass concentration of 70% for phosphoric acid and 30% for nitric acid. The two are mixed in a volume ratio of 1:1.

[0053] Step (5) The electrolyte contains a base electrode solution and a modifying additive. The base electrode solution contains oxalic acid, phosphoric acid and sulfuric acid, with a concentration of 40 g / L for oxalic acid, 20 g / L for phosphoric acid and 5 g / L for sulfuric acid. The modifying additive contains polyethylene glycol, potassium titanium oxalate and citric acid, with a concentration of 10 g / L for polyethylene glycol, 10 g / L for potassium titanium oxalate and 10 g / L for citric acid.

[0054] Step (6) The passivation solution consists of chromic anhydride, sodium fluoride and water. The concentration of chromic anhydride is 200 g / L, the concentration of sodium fluoride is 20 g / L, and the solvent is water.

[0055] Example 3

[0056] A method for preparing a superhydrophobic aluminum profile includes the following preparation steps:

[0057] (1) Batching and smelting: Batching is carried out according to the following mass percentages: Cu 8%, Fe 5%, Mn 9%, Mg 2%, Zn 2%, Si 0.8%, Ni 0.1%, Ti 0.05%, Zr 0.1%, Y 0.05%, Sc 0.03%, with the remainder being Al and unavoidable impurities. The total amount of unavoidable impurities is ≤0.1%. The mixture is smelted at high temperature for 6-8 hours to obtain aluminum alloy melt; then refined and cast to obtain cast rods.

[0058] (2) The cast rod obtained in step (1) is placed in a homogenizing furnace and heated to 550°C for 15 hours. After the homogenization treatment is completed, it is cooled. The cast rod is then extruded and aged to obtain aluminum alloy profiles.

[0059] (3) Immerse the aluminum alloy profile in an alkaline degreasing solution at 55-60℃ for 5 minutes to remove oil stains, take it out, and wash it with water.

[0060] (4) Then immerse it in an acidic solution at 50-55℃ for 40 seconds to improve the surface smoothness;

[0061] (5) Anodizing treatment: The aluminum alloy substrate treated in step (4) is anodized in an electrolyte, with the aluminum alloy as the anode and the aluminum plate as the cathode. The oxidation voltage is 20V and the current density is 2A / dm³. 2 The electrolyte temperature is 10-20℃, and the oxidation time is 40 minutes; then the voltage is increased to 80-100V, and the oxidation time is 30 minutes. Air stirring is used during the anodizing process.

[0062] (6) Post-treatment: The anodized profile is treated with hot air at 100-120℃ for 30 minutes; then the treated aluminum alloy substrate is immersed in passivation solution at 80-85℃ for 30 minutes, taken out and drained of surface moisture, and dried at 80-90℃ for 4 hours to obtain the preparation method of superhydrophobic aluminum profile.

[0063] In step (2), the aging temperature is 165-175℃ and the aging time is 12h.

[0064] The alkaline degreasing solution in step (3) consists of 50 g / L NaOH, 20 g / L Na3PO4, and water as the solvent.

[0065] Step (4) The acidic solution is a mixture of phosphoric acid and nitric acid, with a mass concentration of 70% for phosphoric acid and 30% for nitric acid. The two are mixed in a volume ratio of 1:1.

[0066] Step (5) The electrolyte contains a base electrode solution and a modifying additive. The base electrode solution contains oxalic acid, phosphoric acid and sulfuric acid, with a concentration of 40 g / L for oxalic acid, 20 g / L for phosphoric acid and 5 g / L for sulfuric acid. The modifying additive contains polyethylene glycol, potassium titanium oxalate and citric acid, with a concentration of 10 g / L for polyethylene glycol, 10 g / L for potassium titanium oxalate and 10 g / L for citric acid.

[0067] Step (6) The passivation solution consists of chromic anhydride, sodium fluoride and water. The concentration of chromic anhydride is 200 g / L, the concentration of sodium fluoride is 20 g / L, and the solvent is water.

[0068] Comparative Example 1

[0069] This comparative example is identical to Example 3 in all raw materials and processing methods except that Zr is not added to the alloy composition. That is:

[0070] A method for preparing a superhydrophobic aluminum profile includes the following preparation steps:

[0071] (1) Batching and smelting: Batching according to mass percentage: Cu 8%, Fe 5%, Mn 9%, Mg 2%, Zn 2%, Si 0.8%, Ni 0.1%, Ti 0.05%, Y 0.05%, Sc 0.03%, the remainder being Al and unavoidable impurities, the total amount of unavoidable impurities being ≤0.1%, smelting at high temperature for 6-8 hours to obtain aluminum alloy melt; then refining and casting to obtain cast rods.

[0072] Comparative Example 2

[0073] This comparative example is identical to Example 3 in all raw materials and processing methods except that Sc is not added to the alloy composition. That is:

[0074] A method for preparing a superhydrophobic aluminum profile includes the following preparation steps:

[0075] (2) Batching and smelting: Batching is carried out according to the following mass percentages: Cu 8%, Fe 5%, Mn 9%, Mg 2%, Zn 2%, Si 0.8%, Ni 0.1%, Ti 0.05%, Zr 0.1%, Y 0.05%, with the remainder being Al and unavoidable impurities. The total amount of unavoidable impurities is ≤0.1%. The mixture is smelted at high temperature for 6-8 hours to obtain aluminum alloy melt. After refining and casting, the resulting rod is obtained.

[0076] Comparative Example 3

[0077] In this comparative example, except for changing the electrolyte composition (i.e., not using modified additives), the raw materials and process steps are the same as in Example 1. That is, in step (5):

[0078] Step (5) The electrolyte is the basic electrode solution, which contains oxalic acid, phosphoric acid and sulfuric acid, with an oxalic acid concentration of 40 g / L, a phosphoric acid concentration of 20 g / L and a sulfuric acid concentration of 5 g / L.

[0079] Comparative Example 4

[0080] In this comparative example, except for changing the electrolyte composition (i.e., not using polyethylene glycol in the modifying additive), the other raw materials and process steps are the same as in Example 1. That is, in step (5):

[0081] Step (5) The electrolyte contains a base electrode solution and a modified additive. The base electrode solution contains oxalic acid, phosphoric acid and sulfuric acid, with a concentration of 40 g / L for oxalic acid, 20 g / L for phosphoric acid and 5 g / L for sulfuric acid. The modified additive contains potassium titanium oxalate and citric acid, with a concentration of 10 g / L for potassium titanium oxalate and 10 g / L for citric acid.

[0082] Comparative Example 5

[0083] In this comparative example, except for changing the electrolyte composition (i.e., not using potassium titanium oxalate in the modified additives), the other raw materials and process steps are the same as in Example 1. That is, in step (5):

[0084] Step (5) The electrolyte contains a base electrode solution and a modified additive. The base electrode solution contains oxalic acid, phosphoric acid and sulfuric acid, with an oxalic acid concentration of 40 g / L, a phosphoric acid concentration of 20 g / L and a sulfuric acid concentration of 5 g / L. The modified additive contains polyethylene glycol and citric acid, with a polyethylene glycol concentration of 10 g / L and a citric acid concentration of 10 g / L.

[0085] Comparative Example 6

[0086] In this comparative example, except for changing the electrolyte composition (i.e., omitting citric acid in the modified additive), the raw materials and process steps are the same as in Example 1. Specifically, in step (5):

[0087] Step (5) The electrolyte contains a base electrode solution and a modified additive. The base electrode solution contains oxalic acid, phosphoric acid and sulfuric acid, with a concentration of 40 g / L for oxalic acid, 20 g / L for phosphoric acid and 5 g / L for sulfuric acid. The modified additive contains polyethylene glycol and potassium titanium oxalate, with a concentration of 10 g / L for polyethylene glycol and 10 g / L for potassium titanium oxalate.

[0088] Comparative Example 7

[0089] In this comparative example, except for changing the electrolyte composition (i.e., reducing the concentration of each raw material in the modified additive), the other raw materials and process steps are the same as in Example 1. That is, in step (5):

[0090] Step (5) The electrolyte contains a base electrode solution and a modifying additive. The base electrode solution contains oxalic acid, phosphoric acid and sulfuric acid, with a concentration of 40 g / L for oxalic acid, 20 g / L for phosphoric acid and 5 g / L for sulfuric acid. The modifying additive contains polyethylene glycol, potassium titanium oxalate and citric acid, with a concentration of 8 g / L for polyethylene glycol, 8 g / L for potassium titanium oxalate and 8 g / L for citric acid.

[0091] Comparative Example 8

[0092] In this comparative example, except for changing the electrolyte composition (i.e., increasing the concentration of each raw material in the modified additive), the other raw materials and process steps are the same as in Example 1. That is, in step (5):

[0093] Step (5) The electrolyte contains a base electrode solution and a modifying additive. The base electrode solution contains oxalic acid, phosphoric acid and sulfuric acid, with a concentration of 40 g / L for oxalic acid, 20 g / L for phosphoric acid and 5 g / L for sulfuric acid. The modifying additive contains polyethylene glycol, potassium titanium oxalate and citric acid, with a concentration of 12 g / L for polyethylene glycol, 12 g / L for potassium titanium oxalate and 12 g / L for citric acid.

[0094] Performance testing

[0095] The aluminum alloy materials obtained in Examples 1-3 and Comparative Examples 1-8 were subjected to performance tests. The test indicators and methods are as follows:

[0096] Oxide film thickness measurement: According to ISO 2360:2017 "Measurement of thickness of nonconductive coatings on nonmagnetic metallic substrates—Eddy current method", five measurement points were taken for each sample and the average value was calculated. Test instrument: Eddy Current Coating Thickness Gauge (model: Surfix SFN, accuracy ±0.5μm).

[0097] Hardness: The hardness test of the alloy specimens was conducted in accordance with GB / T23.1 standard.

[0098] Contact angle, static contact angle: according to ASTM D7334-21 "Standard Implementation Procedure for Evaluating Surface Wettability by Contact Angle Measurement", deionized water droplet volume 4μL.

[0099] Salt spray test:

[0100] Salt spray test chamber (model: Q-FOG CCT1100, conforming to ASTM B117-22 standard), conditions: 5% NaCl solution, pH 6.5-7.2, temperature 35±2℃, spray pressure 0.8-1.2 bar, continuous spray mode. The time of first occurrence of substrate corrosion was recorded according to ISO 10289:2021 "Corrosion testing and rating methods for conversion coatings and anodic oxide coatings on metallic substrates".

[0101] Mechanical property testing: Universal testing machine (Model: Instron 5985, load accuracy ±0.5%). Tests were conducted according to ASTM E8 / E8M-22 "Metallic materials, tensile testing," with specimen dimensions conforming to scale 5 of ISO 6892-1:2020 (gauge length 50 mm, width 12.5 mm). All performance tests were repeated 10 times, and the results were averaged.

[0102] Table 1 Performance Test Results

[0103]

[0104] As can be seen from the data in the table, the aluminum alloy material obtained in the embodiments of the present invention is significantly superior to the comparative examples in terms of oxide film thickness, hardness, contact angle, and tensile strength, demonstrating excellent comprehensive performance and corrosion resistance. Especially in the salt spray test, the durability time of the embodiments far exceeds that of the comparative examples, further verifying its stability in complex environments. Comparative examples 1-2, which changed the alloy element composition, and comparative examples 3-8, which changed the composition of the modifying additives, failed to achieve the excellent effects of the embodiments. This indicates that the alloy ratio and the use and composition of the modifying agents in the present invention are crucial to improving the comprehensive performance of the material. When Zr or Sc elements are insufficient, the high-temperature stability of the alloy decreases, and the homogenization treatment is insufficient, leading to coarsening of the grains after extrusion (average size > 20 μm), poor oxide film uniformity, and reduced thickness (18-20 μm), thus affecting its corrosion resistance and mechanical strength. Without the addition of modifying additives, the oxide film is highly brittle, with a hardness of only 320 HV, and pitting corrosion occurs after 800 hours of salt spray testing. Without polyethylene glycol in the modifier (Comparative Example 4): the micropore distribution was uneven, and the contact angle decreased to 152°; without potassium titanium oxalate (Comparative Example 5): the film hardness was insufficient, the surface was easily worn, and the contact angle was 148°; without citric acid (Comparative Example 6): the hydrophobic carbon chain was missing, and the contact angle was only 142°. When the concentration of the modifier was adjusted (8 g / L or 12 g / L), the overall performance was slightly lower than that of Example 1, indicating that the synergistic effect of the same concentration (10 g / L) was the best: adjusting the concentration too high or too low affected the overall performance of the material, verifying that 10 g / L was the optimal ratio, ensuring the long-term stability of the material under high temperature and high humidity environments.

[0105] Deep-sea simulated corrosion resistance test:

[0106] Test conditions:

[0107] Solution: 5% NaCl solution (simulating seawater salinity), pH 7.2±0.1.

[0108] Pressure: 5 MPa (simulating the static water pressure at a depth of 5000m), using a high-pressure reactor (model: PARR 4575).

[0109] Temperature: 10±1℃ (simulating the low temperature environment of the deep sea).

[0110] Cyclic shock: pressure fluctuation range of 5±0.5 MPa, frequency of 1 Hz (60 cycles per minute), total test time of 2000 hours.

[0111] Reference standard: ISO 11489:2021 "Metallic materials - High pressure corrosion test method".

[0112] Testing indicators:

[0113] Weight loss rate: calculated according to ASTM G31-21 "Metal Immersion Corrosion Test Standard", with a sample size of 50×25×3 mm. Ten samples were repeated for each experimental group, and the average value was taken.

[0114] Surface morphology: SEM was used to observe pitting corrosion, and EDS was used to analyze corrosion products.

[0115] Table 2 Results of Deep-Sea Simulated Corrosion Resistance Test

[0116]

[0117] As can be seen from the data in Table 2, the weight loss rate of Example 1 (0.04 mg / cm²) is much lower than that of the comparative example, which is attributed to the density of its oxide film and its excellent corrosion resistance. SEM showed that its surface was free of pitting corrosion, and the structure was dense before and after corrosion. The surface self-corrosion products were mainly AlO(OH), i.e., Al₂O₃·H₂O.

[0118] It should be noted that the above embodiments are merely some preferred embodiments of the present invention, and not all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

Claims

1. A method for preparing a superhydrophobic aluminum profile, characterized in that, The preparation steps include the following: (1) Batching and smelting: Batching is carried out according to the following mass percentages: Cu 3-8%, Fe 2-5%, Mn 5-9%, Mg 1-2%, Zn 1-2%, Si 0.5-0.8%, Ni 0.1%, Ti 0.05%, Zr 0.05-0.1%, Y 0.02-0.05%, Sc 0.01-0.03%, with the remainder being Al and unavoidable impurities. The total amount of unavoidable impurities is ≤0.1%. The mixture is smelted at high temperature for 6-8 hours to obtain aluminum alloy melt; then refined and cast to obtain cast rods. (2) The cast rod obtained in step (1) is placed in a homogenizing furnace and heated to 480-550℃ for 10-15 hours. After the homogenization treatment is completed, it is cooled. The cast rod is then extruded and aged to obtain aluminum alloy profiles. (3) Immerse the aluminum alloy profile in an alkaline degreasing solution at 55-60℃ for 3-5 minutes to remove oil stains, take it out, and wash it with water; (4) Then immerse it in an acidic solution at 50-55℃ for 30-40 seconds to improve the surface smoothness; (5) Anodizing treatment: The aluminum alloy substrate treated in step (4) is anodized in an electrolyte, with the aluminum alloy as the anode and the aluminum plate as the cathode. The oxidation voltage is 15-20V and the current density is 1-2A / dm³. 2 The electrolyte temperature is 10-20℃, and the oxidation time is 20-40 minutes; Increase the voltage to 80-100V and oxidize for 20-30 minutes, using air stirring during the anodizing process; (6) Post-treatment: After anodizing, the profile is treated with hot air at 100-120℃ for 30 minutes; then the treated aluminum alloy substrate is immersed in passivation solution at 80-85℃ for 15-30 minutes, taken out and drained of surface moisture, and dried at 80-90℃ for 2-4 hours to obtain superhydrophobic aluminum profile. Step (5) The electrolyte contains a base electrode solution and a modifying additive. The base electrode solution contains oxalic acid, phosphoric acid and sulfuric acid, with a concentration of 40 g / L for oxalic acid, 20 g / L for phosphoric acid and 5 g / L for sulfuric acid. The modifying additive contains polyethylene glycol, potassium titanium oxalate and citric acid, with a concentration of 10 g / L for polyethylene glycol, 10 g / L for potassium titanium oxalate and 10 g / L for citric acid.

2. The method for preparing the superhydrophobic aluminum profile according to claim 1, characterized in that, In step (2), the aging temperature is 165-175℃ and the aging time is 10-12h.

3. The method for preparing the superhydrophobic aluminum profile according to claim 1, characterized in that, The alkaline degreasing solution in step (3) consists of 50 g / L NaOH, 20 g / L Na3PO4, and water as the solvent.

4. The method for preparing the superhydrophobic aluminum profile according to claim 1, characterized in that, Step (4) The acidic solution is a mixture of phosphoric acid and nitric acid, with a mass concentration of 70% for phosphoric acid and 30% for nitric acid. The two are mixed in a volume ratio of 1:

1.

5. The method for preparing the superhydrophobic aluminum profile according to claim 1, characterized in that, Step (6) The passivation solution consists of chromic anhydride, sodium fluoride and water. The concentration of chromic anhydride is 200 g / L, the concentration of sodium fluoride is 20 g / L, and the solvent is water.

6. A method for preparing the superhydrophobic aluminum profile according to any one of claims 1-5, characterized in that, The aluminum alloy profiles prepared by this method can be processed according to actual needs and applied to deep-sea equipment and offshore wind power facilities.

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