A corrosion-resistant treatment process for outdoor aluminum alloy profiles

Abstract

This invention relates to the field of aluminum alloy technology, specifically to a corrosion-resistant treatment process for outdoor aluminum alloy profiles, comprising the following sequential steps: S1, profile pretreatment; S2, sulfuric acid anodizing treatment; S3, rare earth-silane hybrid ultrasonic-assisted pore sealing treatment; S4, fluorosilane hydrophobic modification treatment; S5, post-treatment. The pretreatment process in this invention involves a series of steps: alkaline degreasing, alkaline etching, acid neutralization, and multi-stage pure water washing. The alkaline degreasing uses a sodium carbonate-trisodium phosphate composite system, which can simultaneously remove stamping and stretching lubricating oil and processing dust from the profile surface. This invention, through multi-step synergistic innovation including pretreatment, anodizing, ultrasonic rare earth silane pore sealing, and fluorosilane hydrophobic modification, addresses problems such as incomplete micropore sealing, lack of long-term UV shielding, surface hydrophilicity leading to easy corrosion, and rapid failure of rare earth components in existing technologies. It combines excellent protective performance, industrial production feasibility, and environmental advantages.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy technology, specifically to a corrosion-resistant treatment process for outdoor aluminum alloy profiles. Background Technology

[0002] Aluminum alloy profiles, with their advantages of lightweight, easy forming, and high cost-effectiveness, are widely used in outdoor components such as building curtain walls, outdoor doors and windows, and photovoltaic brackets, which are exposed to the atmosphere, salt spray, and ultraviolet radiation for extended periods. However, the aluminum alloy substrate itself has high chemical reactivity, and the passivation film on the substrate alone cannot resist the continuous corrosion from outdoor chloride ions, rainwater, and ultraviolet radiation. The mainstream industry solution is sulfuric acid anodizing combined with pore-sealing post-treatment to create a porous alumina film to block corrosive media. However, existing complete treatment processes still suffer from practical problems such as incomplete pore sealing, lack of a long-term hydrophobic barrier, insufficient resistance to ultraviolet aging, and short outdoor service life. The relevant existing technical solutions have significant shortcomings, as detailed below: Publication number CN102677039A, invention titled "A Silane-Rare Earth Composite Protective Film for Aluminum and Aluminum Alloy Surfaces and Its Preparation Method," discloses a two-step silane-rare earth composite film-forming process. First, the film is immersed in a silane hydrolysis solution, followed by a secondary immersion in a rare earth salt passivation solution. The corrosion resistance is enhanced synergistically by the silane organic film and rare earth hydroxides. However, this method is only suitable for direct film formation on bare aluminum substrates and lacks a supporting anodic oxide porous substrate structure. The composite film only adheres to the aluminum substrate surface, without an aluminum oxide film as a buffer support layer, resulting in a thin film thickness and weak erosion resistance. Furthermore, the process lacks ultrasonic-assisted permeation, causing the rare earth and silane components to accumulate only on the substrate surface, failing to fill the micropores. Additionally, the lack of a fluorosilane hydrophobic modification process results in a hydrophilic film surface, making it highly susceptible to continuous wetting by salt spray and rainwater. Long-term outdoor use is prone to pitting corrosion and loss of gloss, making it unsuitable for harsh outdoor conditions such as photovoltaic applications and curtain walls.

[0003] Publication number CN110857475B, invention title "A sealing agent for aluminum alloy anodic oxide film, preparation method and sealing method", this solution provides a sealing agent containing lanthanum rare earth, silane and molybdate compound, which directly seals the anodic oxide film at room temperature under static conditions. It relies on the synergistic sealing of rare earth salt and silane to block the micropores of the oxide film and improve the color fading problem of dyed profiles. National Science and Technology Enterprise Knowledge Transformation Platform. This patent focuses solely on optimizing the sealing solution formulation and has three core defects: First, the sealing process relies solely on static immersion, resulting in air bubbles trapped within the micropores of the oxide film, hindering the sealing components from penetrating the pores. This only forms a thin sealing layer on the film surface, leaving channels for corrosive media to penetrate deep into the micropores. Second, the entire process lacks a post-processing step of low surface energy hydrophobic modification, leading to strong water wettability on the film surface. Chloride ions and water vapor are easily adsorbed onto the profile surface for extended periods, significantly shortening the corrosion protection lifespan. Third, it does not incorporate an EDTA-based cerium ion slow-release complexation system. Rare earth ions rapidly hydrolyze and precipitate at the pore inlet upon contact with water, leaving insufficient rare earth passivation components inside the pores. Consequently, the sealing effect rapidly diminishes under long-term salt spray conditions.

[0004] The invention, published under CN106119924B and titled "A Sealing Method for Improving the Alkali Resistance and Corrosion Resistance of Anodized Films on Aluminum and Aluminum Alloys," employs a single silane system for sealing. It enhances the alkali resistance of the anodic oxide film by adjusting the pH of silane hydrolysis, relying solely on an organosiloxane network to block the oxide film pores. This method completely lacks rare-earth passivation components and thus lacks UV shielding and electrochemical corrosion inhibition functions. Furthermore, the silane organic film is prone to photo-oxidation and chain breakage under prolonged UV irradiation, resulting in severe film powdering and loss of gloss, failing to meet the requirements for long-term outdoor exposure. Simultaneously, it lacks ultrasonic-assisted sealing and a gradient-cured hydrophobic fluorosilane layer, leading to poor pore sealing integrity and a lack of surface hydrophobicity and anti-fouling capabilities. It can only meet the protection requirements of ordinary indoor aluminum parts and is unsuitable for outdoor high-corrosion and strong UV environments.

[0005] In summary, existing technologies have several problems: First, rare earth-silane sealing only involves static immersion, resulting in insufficient filling of the micropores and allowing corrosive media to easily penetrate the pores and contact the aluminum substrate; second, the lack of a cerium ion slow-release complexation system leads to rapid precipitation of rare earth components at the pore openings, without long-term passivation; third, the absence of ultrasonic cavitation-assisted penetration methods makes it difficult for the sealing components to penetrate deep into the micron-level oxide channels; and fourth, the lack of a fluorosilane gradient curing hydrophobic modification process results in a hydrophilic profile surface, leading to continuous adhesion of salt spray and rainwater, which accelerates corrosion and aging. To address these shortcomings of existing technologies, this invention proposes a complete corrosion-resistant treatment process for outdoor aluminum alloy profiles. Through a multi-layered synergistic protection system consisting of graded pretreatment, regular anodizing pore formation, ultrasonic-assisted rare earth-silane hybrid sealing, and fluorosilane gradient curing hydrophobic modification, this process simultaneously solves the corrosion and UV aging problems of outdoor aluminum profiles from three dimensions: pore sealing, interface passivation, and surface hydrophobicity. Summary of the Invention

[0006] The purpose of this invention is to provide a corrosion-resistant treatment process for outdoor aluminum alloy profiles.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A corrosion-resistant treatment process for outdoor aluminum alloy profiles includes the following steps performed sequentially: S1. Profile Pretreatment: Outdoor aluminum alloy profiles of grade 6061 or 6063 are subjected to alkaline degreasing, alkaline etching, acid neutralization, and multi-stage flowing pure water washing in sequence. The alkaline degreasing uses a sodium carbonate-trisodium phosphate composite degreasing system, with a degreasing temperature of 50-60℃ and a degreasing time of 8-12 minutes. The alkaline etching uses a sodium hydroxide aqueous solution with a mass concentration of 50-60 g / L, with an alkaline etching temperature of 45-50℃ and an alkaline etching time of 3-5 minutes. The acid neutralization uses a dilute sulfuric acid aqueous solution with a mass concentration of 10-15 g / L and a neutralization time of 2-3 minutes. Each washing process uses room temperature flowing pure water for rinsing, with a single washing duration of ≥2 minutes to thoroughly remove residual agents and impurities from the profile surface. S2. Sulfuric Acid Anodizing Treatment: Using the previously treated and dried aluminum alloy profile as the anode, DC anodizing treatment is performed using a sulfuric acid aqueous solution electrolyte. The sulfuric acid mass concentration in the electrolyte is 150–180 g / L, the oxidation tank temperature is 15–22℃, and the anode current density is 1.2–1.8 A / dm³. 2 The oxidation working voltage is 14-18V, the oxidation time is 30-50min, and finally a γ-Al2O3 anodic oxide film is uniformly generated on the outer surface of the profile. S3. Rare Earth-Silane Hybrid Ultrasonic-Assisted Sealing Treatment: The profile, after anodizing and rinsing with pure water while maintaining a moist surface, is completely immersed in a prepared rare earth-silane hybrid sealing solution for constant-temperature sealing. The pH of the sealing solution is precisely adjusted to 5.5–6.5 using dilute ammonia. The sealing temperature is maintained at 40–55℃, and the total sealing time is 20–40 minutes. The entire sealing process utilizes a frequency of 20–28 kHz and a power density of 0.3–0.5 W / cm². 2 Low-frequency continuous ultrasonic-assisted dispersion is used to promote deep pore penetration of components by utilizing the ultrasonic cavitation effect; the sealing liquid is uniformly prepared by a stepwise preparation process of silane pre-hydrolysis and cerium salt complexation slow release. S4. Fluorosilane hydrophobic modification treatment: After rinsing the sealed profile with pure water to remove residual sealing liquid, place it at 60-70℃ for low-temperature drying for 8-10 minutes. After the profile surface is completely dry, immerse it in a mixed modification solution of perfluorooctyltriethoxysilane that has been fully hydrolyzed by acid catalysis and immerse it at room temperature for 5-10 minutes. After immersion, take out the profile and use a segmented gradient temperature curing method to cure it, forming a low surface energy hydrophobic protective layer on the surface of the anodic oxide film. S5. Post-treatment: After the cured profile is thoroughly rinsed with pure water, it is placed in a constant temperature drying equipment at 110-120℃ and dried for 15-20 minutes. After drying, the surface moisture content of the profile is controlled to be ≤0.5%, and finally an outdoor aluminum alloy profile with both high corrosion resistance and UV aging resistance is obtained.

[0008] As a further technical solution, the sealing solution in step S3 is composed of the following components by mass concentration: cerium nitrate hexahydrate 3-8 g / L, silane coupling agent KH-560 2-5 g / L, hexamethylenetetramine 0.5-1.5 g / L, and the balance being deionized water.

[0009] As a further technical solution, the preparation process of the rare earth-silane hybrid sealing liquid specifically includes the following sequential operation steps: B1. Silane pre-hydrolysis: Take the silane coupling agent KH-560 according to the formula, add it to 20% of the corresponding mass of deionized water, add glacial acetic acid dropwise to adjust the pH of the system to 4.0-4.5, and continuously stir magnetically at room temperature for 30-60 minutes to obtain a transparent pre-hydrolyzed silane sol with uniform components and no agglomeration precipitate. B2. Cerium salt complexation modification: Take cerium nitrate hexahydrate according to the formula, add it to the remaining proportion of deionized water, add cerium ion slow-release complexing agent, and continue stirring until the solid is completely dissolved to prepare a homogeneous and stable cerium salt aqueous solution. B3. Hybrid Mixing: The cerium salt aqueous solution prepared in step B2 is slowly added dropwise at a uniform rate of 2-4 mL / min to the pre-hydrolyzed silane sol prepared in step B1, while simultaneously adding a measured amount of hexamethylenetetramine. The mixture is stirred continuously at a constant temperature and speed of 300-400 r / min for 20-30 min. The reverse dropwise addition avoids sudden pH changes caused by acid-base reactions, preventing the silane sol from agglomerating and failing. After stirring, the pH of the system is precisely adjusted to 5.5-6.5 using dilute ammonia. The mixture is allowed to stand for 10-15 min to remove bubbles and small air bubbles, resulting in a stable, non-agglomerated rare earth-silane hybrid sealing solution.

[0010] As a further technical solution, in step B1, during the pre-hydrolysis of silane, the magnetic stirring speed is constantly controlled at 250-350 r / min, and the hydrolysis process can be carried out at room temperature in a sealed container to ensure uniform hydrolysis of silane and stability of the system.

[0011] As a further technical solution, the cerium ion slow-release complexing agent in step B2 is EDTA-2Na; wherein, EDTA-2Na reacts with Ce in the solution. 3+ The molar ratio is 0.2 to 0.5:1, which effectively delays the rapid precipitation and failure of cerium ions at the pore opening through weak complexation and slow release.

[0012] As a further technical solution, in step B2, during the cerium salt complexation modification process, the system dissolution temperature is controlled at 15-30℃, and the continuous stirring dissolution time is 15-20 min, to ensure that EDTA-2Na and cerium ions are fully coordinated and complexed to form a stable slow-release complexation system.

[0013] As a further technical solution, during the entire process of sealing in step S3, the sealing liquid adopts a constant temperature circulation filtration mode with a circulation filtration accuracy of 0.22μm. This mode intercepts and removes trace particles and agglomerated impurities generated in the system in real time, continuously ensuring the uniformity of the sealing liquid components and ensuring that the film layer on the profile surface is deposited evenly, densely, and without defects.

[0014] As a further technical solution, the specific formulation of the perfluorooctyltriethoxysilane mixed modification liquid in step S4 is as follows: the amount of perfluorooctyltriethoxysilane added is 1-3 wt%, and the solvent is a mixture of ethanol and deionized water, wherein the volume ratio of ethanol to deionized water is 80:20.

[0015] As a further technical solution, the modified solution needs to undergo acid-catalyzed hydrolysis pretreatment before formal use: add 0.1wt% glacial acetic acid to the prepared modified solution, seal and let it stand at room temperature for 30-40 minutes to ensure that the highly hydrophobic fluorosilane is fully hydrolyzed to generate active hydroxyl groups, thus ensuring the subsequent chemical bonding and grafting effect with the film layer.

[0016] As a further technical solution, the specific operating parameters of the segmented gradient temperature curing process in step S4 are as follows: First, pre-curing is carried out at 80℃ for 10 minutes to complete the initial cross-linking and shaping, and then the temperature is raised to 90~100℃ for constant temperature curing for 10~20 minutes to achieve complete cross-linking and curing of the film layer; the relative humidity of the environment is controlled at 40%~60% throughout the curing process, and a trace amount of water vapor is reserved to participate in the silane condensation reaction, which avoids defects caused by excessive water vapor and ensures that the film layer is fully cross-linked and cured.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. In the technical solution of this invention, the graded pretreatment process sequentially includes alkaline degreasing, alkaline etching, acid neutralization, and multi-stage pure water washing. The alkaline degreasing uses a sodium carbonate-trisodium phosphate composite system, which can simultaneously remove stamping and stretching lubricating oil and processing dust from the profile surface. The alkaline etching moderately etches the natural oxide layer on the surface of the aluminum substrate. The acid neutralization eliminates residual hydroxide ions from the alkaline etching. The multi-stage flowing pure water washing lasts for ≥2 minutes per cycle, which can thoroughly remove residual acid and alkali agents from the profile surface. Because the complete graded pretreatment removes oil stains, uneven oxide layers, and residual acid and alkali impurities from the substrate surface, it avoids uneven local film growth, pinholes, and pitting defects during the anodizing stage. This solves the problem of disordered oxide film pore structure and weak adhesion of sealing components caused by the simplification of pretreatment in existing processes. A uniform and continuous γ-Al2O3 oxide film can be generated on the clean and orderly substrate surface, providing a stable adhesion substrate for subsequent sealing and hydrophobic modification.

[0018] This invention employs sulfuric acid anodizing, which strictly limits the range of electrolyte sulfuric acid concentration, tank temperature, current density, and oxidation time to generate a γ-Al₂O₃ porous membrane with uniform pore size and consistent channel depth. Because the stable and controllable anodizing process constructs a regular and interconnected microporous structure, it provides ample space for rare earth cerium ions and silane molecules, thereby increasing the filling capacity of the sealing components and addressing the shortcomings of existing processes, such as uneven pore size, numerous shallow pores, and insufficient sealing filling.

[0019] The sealing solution in this invention is a compound of cerium nitrate hexahydrate, KH-560 silane, and hexamethylenetetramine, and EDTA-2Na is introduced as a cerium ion slow-release complexing agent. EDTA-2Na reacts with Ce... 3+ A weakly coordinated complex is formed, resulting in the slow release of cerium ions. This is because the complex-based slow-release system delays the release of cerium ions. 3+ The hydrolysis and precipitation rate allows cerium ions to penetrate deep into the micropores of the oxide film along with the silane sol, continuously hydrolyzing inside the pores to generate a cerium oxide passivation layer. This forms an electrochemical corrosion inhibition barrier on the inner wall of the micropores, thus solving the defects of existing rare earth sealing solutions where rare earth only accumulates at the pore opening, lacks internal passivation components, and experiences rapid failure of long-term corrosion protection. KH-560 silane hydrolysis generates silanol groups, which can dehydrate and condense with the hydroxyl groups of the alumina film to form Si-O-Al covalent bonds, firmly adhering to the inner wall of the micropores. The organosiloxane network fills the micropore gaps, further blocking the chloride ion diffusion channels. Hexamethylenetetramine acts as a pH buffer, stabilizing the sealing solution within the pH range of 5.5–6.5, preventing abrupt acid-base changes in the silane sol and agglomeration failure, and ensuring the long-term stable recycling of the sealing solution.

[0020] This invention employs 20–28 kHz low-frequency ultrasonic-assisted sealing throughout the entire process. The ultrasonic cavitation effect generates microbubbles that impact and break up air trapped within the micropores of the oxide film. The bursting of these bubbles generates microjets that scour the inner walls of the pores, removing the air barrier layer and allowing the sealing liquid to completely penetrate to the deepest part of the micropores. This achieves full-depth filling of the micropores, thus solving the problems of incomplete sealing and the existence of permeation channels in static soaking sealing. A 0.22 μm constant-temperature circulating filtration continuously removes trace agglomerates of the sealing liquid, preventing particle defects on the membrane surface and improving the density and uniformity of the membrane.

[0021] This invention incorporates a hydrophobic modification process using perfluorooctyltriethoxysilane. The modified solution undergoes thorough hydrolysis catalyzed by glacial acetic acid, resulting in silane molecules carrying active hydroxyl groups. The process employs a two-stage gradient curing method: pre-curing at 80°C and curing at 90–100°C. This staged gradient curing first achieves initial cross-linking and shaping between the silane and the hydroxyl groups on the oxide film surface, followed by complete condensation to form a dense fluorosilane molecular layer. The outward arrangement of the fluoroalkyl groups creates a low surface energy interface, significantly reducing the water contact angle on the profile surface and achieving a strong hydrophobic effect. This solves the problems of existing processes, such as the lack of a hydrophobic layer, continuous wetting of the film by salt spray and rainwater, and accelerated corrosion and aging. The curing environment humidity is controlled at 40%–60%, with trace amounts of water vapor assisting silane condensation and preventing film cracking and porosity defects.

[0022] In the technical solution of this invention, each process step and each functional component does not play an independent role, but forms a four-level continuous synergistic protection system: "pretreatment to regularize the substrate - anodic oxidation to create a pore carrier - rare earth silane micropore passivation and sealing - fluorosilane surface hydrophobic barrier". The system is progressively enhanced layer by layer, thereby improving corrosion resistance and weather resistance.

[0023] First, the S1 clean substrate and the S2 regular porous oxide film form a basic synergy. Only a clean and impurity-free aluminum surface can generate a γ-Al2O3 film with uniform pores. If there are oil stains or impurities in the pretreatment, the oxide film will have local pore deformities, and subsequent sealing and hydrophobic modification will not be able to achieve complete coverage. The regular microporous structure provides a carrier for rare earth and silane components. Without the support of the porous oxide film, the rare earth silane film will only float on the surface and will be easily worn off.

[0024] Secondly, the S3 rare earth-silane hybrid sealing process forms a synergistic effect between the components inside the pores. The slow-release cerium salt and silane coupling agent simultaneously penetrate the micropores, and the silane organic network physically blocks the pores. The cerium oxide provides electrochemical corrosion inhibition and ultraviolet shielding, and the two complement each other: pure silane membranes lack ultraviolet absorption capacity and are easily degraded by long-term exposure to sunlight; pure rare earth inorganic passivation layers are brittle and prone to cracking, while the silane organic phase can toughen the passivation membrane and reduce the risk of membrane cracking. The supporting ultrasonic-assisted and circulating filtration process further amplifies the synergistic effect of the two, allowing the two functional components to simultaneously fill the microporous area, achieving synergistic protection of "physical sealing and electrochemical passivation" of the pores.

[0025] Finally, the S3 inner composite sealing layer and the S4 surface fluorosilane hydrophobic film form a dual-layer synergistic protection. The inner rare-earth silane sealing layer blocks the diffusion of corrosive media into the aluminum substrate from the inside of the membrane pores, while absorbing ultraviolet light to prevent direct UV damage to the aluminum substrate interface. The surface fluorosilane low surface energy film isolates water vapor and salt spray from contact with the film layer, significantly reducing the amount of corrosive media adsorbed and lowering the long-term immersion load of the inner sealing layer. Without the fluorosilane hydrophobic layer, continuous salt spray wetting will accelerate the hydrolytic aging of the inner silane layer; without the rare-earth silane sealing inner layer, once the fluorosilane film has minor scratches, chloride ions can directly penetrate and contact the aluminum substrate, causing rapid pitting corrosion.

[0026] This invention addresses the problems of incomplete micropore sealing, lack of long-term UV shielding, easy corrosion due to surface hydrophilicity, and rapid failure of rare earth components in existing technologies through multi-step collaborative innovation, including pretreatment, anodizing, ultrasonic rare earth silane sealing, and hydrophobic modification of fluorosilane. It combines excellent protective performance, feasibility for industrial production, and environmental advantages, and has significant value for industrial promotion. Attached Figure Description

[0027] Figure 1 This is a schematic diagram comparing the average static water contact angle (°) of the embodiments of the present invention with that of the comparative examples. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] This invention provides a corrosion-resistant treatment process for outdoor aluminum alloy profiles, comprising the following steps performed sequentially: S1. Profile pretreatment: Outdoor aluminum alloy profiles of grade 6061 or 6063 are subjected to alkaline degreasing, alkaline etching, acid neutralization and multi-stage flowing pure water washing in sequence. S2. Sulfuric acid anodizing treatment: The previously treated and dried aluminum alloy profile is used as the anode, and DC anodizing treatment is performed using sulfuric acid aqueous solution electrolyte, which ultimately generates a uniform γ-Al2O3 anodic oxide film on the outer surface of the profile. S3. Rare Earth-Silane Hybrid Ultrasonic-Assisted Sealing Treatment: After anodizing and cleaning with pure water, the profile, with its surface kept moist, is completely immersed in the prepared rare earth-silane hybrid sealing solution for constant temperature sealing treatment. The entire sealing process uses low-frequency continuous ultrasonic-assisted dispersion to promote deep pore penetration of components by utilizing the ultrasonic cavitation effect. The sealing solution is uniformly prepared using a stepwise preparation process of silane pre-hydrolysis and cerium salt complexation slow release. S4. Fluorosilane hydrophobic modification treatment: After the sealing of the profile is completed, rinse it with pure water to remove the residual sealing liquid on the surface and dry it at low temperature. After the surface of the profile is completely dry, immerse it in a mixed modification solution of perfluorooctyltriethoxysilane that has been fully hydrolyzed by acid catalysis at room temperature. After immersion, take out the profile and cure it using a segmented gradient temperature curing method to form a low surface energy hydrophobic protective layer on the surface of the anodic oxide film. S5. Post-treatment: After curing, rinse the profile thoroughly with pure water and dry it at a constant temperature. After drying, control the surface moisture content of the profile to ≤0.5% to finally obtain an outdoor aluminum alloy profile with both high corrosion resistance and UV aging resistance.

[0030] Detailed explanation of process parameters for each step: (a) Step S1: Profile pretreatment This invention uses 6061 or 6063 outdoor aluminum alloy profiles as the base material. Both types of profiles are directly applicable to this process; commercially available standard industrial aluminum profiles are sufficient, with no special customization requirements. The alkaline degreasing uses a sodium carbonate-trisodium phosphate composite degreasing system. The preferred degreasing temperature is 50–60℃, more preferably 52–58℃; the preferred degreasing time is 8–12 min, more preferably 9–11 min. The alkaline etching uses a 50–60 g / L sodium hydroxide aqueous solution. The preferred alkaline etching temperature is 45–50℃, more preferably 46–49℃; the preferred alkaline etching time is 3–5 min, more preferably 3.5–4.5 min. The acid neutralization uses a 10–15 g / L dilute sulfuric acid aqueous solution. The preferred neutralization time is 2–3 min, more preferably 2.2–2.8 min. Each washing process uses room temperature flowing pure water for rinsing. The duration of a single wash is preferably ≥2 minutes. Sufficient washing time can thoroughly remove residual agents and impurities from the surface of the profile, avoiding pinholes and pitting defects in the film layer in subsequent processes.

[0031] (II) Step S2: Sulfuric acid anodizing treatment: The preferred sulfuric acid concentration in the electrolyte is 150–180 g / L, more preferably 160–170 g / L; the preferred constant temperature of the oxidation tank is 15–22 °C, more preferably 17–20 °C; and the preferred anode current density is 1.2–1.8 A / dm³. 2 More preferably 1.4 to 1.6 A / dm 2 The oxidation working voltage is preferably 14–18V, more preferably 15–17V; the continuous oxidation time is preferably 30–50 min, more preferably 35–45 min. Within the above parameter range, a γ-Al2O3 anodic oxide film with uniform thickness and regular pore structure can be generated, providing a stable substrate for subsequent sealing and hydrophobic modification.

[0032] (III) Step S3: Rare Earth-Silane Hybrid Ultrasonic-Assisted Sealing Treatment The pH value of the sealing solution is preferably 5.5–6.5, more preferably 5.8–6.2; the sealing constant temperature is preferably 40–55℃, more preferably 45–52℃; the total sealing time is preferably 20–40 min, more preferably 25–35 min; the ultrasonic frequency is preferably 20–28 kHz, more preferably 22–26 kHz; and the ultrasonic power density is preferably 0.3–0.5 W / cm³. 2 More preferably 0.35–0.45 W / cm 2The sealing solution consists of the following components by mass concentration: cerium nitrate hexahydrate, preferably 3-8 g / L, more preferably 4-7 g / L; silane coupling agent KH-560, preferably 2-5 g / L, more preferably 2.5-4 g / L; hexamethylenetetramine, preferably 0.5-1.5 g / L, more preferably 0.8-1.2 g / L, with the balance being deionized water.

[0033] Stepwise preparation process of rare earth-silane hybrid sealing solution: B1 Silane Pre-hydrolysis: Silane coupling agent KH-560 is added to 20% by mass of deionized water, and the pH of the system is adjusted to 4.0-4.5, more preferably 4.1-4.4, with glacial acetic acid; the magnetic stirring speed is preferably 250-350 r / min, more preferably 280-320 r / min; the hydrolysis time is preferably 30-60 min, more preferably 40-50 min, and a transparent pre-hydrolyzed silane sol is obtained by sealing and stirring at room temperature.

[0034] B2 Cerium Salt Complexation Modification: EDTA-2Na was selected as the complexing agent, and EDTA-2Na and Ce... 3+ The preferred molar ratio is 0.2–0.5:1, more preferably 0.3–0.4:1; the preferred dissolution temperature is 15–30°C, more preferably 20–25°C; the preferred stirring and dissolution time is 15–20 min, more preferably 16–19 min, and the mixture is stirred until the solid is completely dissolved to obtain a stable cerium salt aqueous solution.

[0035] B3 hybrid compound mixing: The preferred drop rate of cerium salt aqueous solution is 2-4 mL / min, more preferably 2.5-3.5 mL / min; the preferred stirring speed throughout is 300-400 r / min, more preferably 320-380 r / min; the preferred stirring and mixing time is 20-30 min, more preferably 22-28 min; the preferred standing time for defoaming after adjusting the pH to 5.5-6.5 with dilute ammonia is 10-15 min, more preferably 12-14 min.

[0036] The sealing fluid adopts a constant temperature circulation filtration mode throughout the sealing process, with a circulation filtration accuracy of 0.22μm. It continuously filters and removes trace particulate impurities from the system, ensuring uniform and defect-free membrane deposition.

[0037] (iv) Step S4: Fluorosilane hydrophobic modification treatment: Modified liquid formulation: The amount of perfluorooctyltriethoxysilane added is preferably 1-3 wt%, more preferably 1.5-2.5 wt%; the volume ratio of solvent ethanol to deionized water is fixed at 80:20. Acid-catalyzed hydrolysis pretreatment: The amount of glacial acetic acid added is preferably 0.1 wt%, and the hydrolysis time at room temperature with sealing and standing is preferably 30-40 min, more preferably 32-38 min. Impregnation process temperature is room temperature, and the impregnation time is preferably 5-10 min, more preferably 6-9 min. Segmented gradient temperature curing: The pre-curing temperature is preferably 80℃, and the pre-curing time is preferably 10 min; the second-stage curing temperature is preferably 90-100℃, more preferably 92-98℃; the second-stage curing time is preferably 10-20 min, more preferably 12-18 min; the relative humidity of the curing environment is preferably 40%-60%, more preferably 45%-55%. Low-temperature drying parameters: The drying temperature is preferably 60-70℃, more preferably 62-68℃; the drying time is preferably 8-10 min, more preferably 8.5-9.5 min.

[0038] (v) Post-processing of step S5: The preferred constant temperature drying temperature is 110-120℃, more preferably 112-118℃; the preferred drying time is 15-20 min, more preferably 16-19 min; and the surface moisture content of the profile after drying is controlled to be ≤0.5%.

[0039] This invention utilizes conventional 6061 and 6063 aluminum profiles as the substrate, constructing a multi-level composite protection system through pretreatment for impurity removal, anodizing for pore formation, rare-earth silane ultrasonic sealing, and fluorosilane hydrophobic modification. The rare-earth-silane hybrid sealing layer seals the pores of the oxide film, while the fluorosilane layer provides a low surface energy hydrophobic barrier. This dual protection significantly improves resistance to salt spray corrosion and UV aging in outdoor environments. The process parameters are wide-range, production is highly stable, ultrasonic-assisted sealing shortens the sealing cycle, and circulating filtration of the sealing solution extends the service life of the bath solution, reducing production costs. It is suitable for the mass industrial production of aluminum profiles for outdoor doors and windows, curtain walls, photovoltaic brackets, and other applications.

[0040] In all embodiments of this invention, the substrate is uniformly selected from 6063 grade industrial aluminum alloy profiles, and the sample size is uniformly 100mm×50mm×2mm; the raw materials are all commercially available industrial-grade reagents: sodium carbonate, trisodium phosphate, sodium hydroxide, concentrated sulfuric acid, cerium nitrate hexahydrate, silane coupling agent KH-560, hexamethylenetetramine, EDTA-2Na, glacial acetic acid, perfluorooctyltriethoxysilane, and anhydrous ethanol; the deionized water is prepared by an industrial pure water machine with a resistivity ≥18.2MΩ·cm. Example 1:

[0041] S1 profile pretreatment: Alkaline degreasing: Sodium carbonate-trisodium phosphate composite degreasing bath solution, temperature 50℃, profile continuously immersed for 8 minutes; Alkaline etching: 50 g / L sodium hydroxide aqueous solution, bath temperature 45℃, immersion of profiles for 3 min; Acid neutralization: Neutralize soaking in a 10 g / L dilute sulfuric acid aqueous solution for 2 minutes; Multi-stage pure water washing: Three stages of ambient temperature flowing pure water rinsing, with each stage lasting 2 minutes, thoroughly rinsing away residual chemicals from the profile surface.

[0042] S2 Sulfuric Acid Anodizing Treatment: Prepare sulfuric acid electrolyte with a sulfuric acid concentration of 150 g / L; maintain a constant temperature of 15℃ in the oxidation tank; use profiles as the anode and pure lead plates as the cathode; anode current density is 1.2 A / dm³. 2 The working voltage is 14V, and the oxidation is carried out continuously for 30 minutes. A uniform γ-Al2O3 oxide film is generated on the surface of the profile. After removal, the profile is rinsed with three-stage pure water and the surface is kept moist.

[0043] S3 Rare Earth-Silane Hybrid Ultrasonic-Assisted Sealing Treatment: Step 1: Preparation of Sealing Solution B1 Silane Pre-hydrolysis: Measure 2g of silane coupling agent KH-560, add 20% (by mass) of deionized water to the total silane formulation, and adjust the pH to 4.0 by adding glacial acetic acid dropwise; Magnetic stirring at 250 r / min, sealed and stirred at room temperature for 30 min to hydrolyze, yielding a transparent silane sol. B2 Cerium Salt Complexation Modification: Measure 3g of cerium nitrate hexahydrate, add the remaining deionized water, and add EDTA-2Na. EDTA-2Na and Ce... 3+ The molar ratio was 0.2:1; the system temperature was 15℃, and the mixture was stirred continuously for 15 min until the solid was completely dissolved to obtain a cerium salt aqueous solution. B3 hybrid compound was mixed: the cerium salt aqueous solution was added dropwise to the silane sol at a uniform rate of 2 mL / min, with 0.5 g of hexamethylenetetramine added simultaneously; the mixture was stirred at a constant temperature of 300 r / min for 20 min; the pH of the system was adjusted to 5.5 with dilute ammonia, and the mixture was allowed to stand for 10 min to defoam; deionized water was then added to a final volume of 1 L to obtain the finished sealing solution.

[0044] The second step, sealing, involves completely immersing the profile in the sealing solution, maintaining the pH of the solution at 5.5 with dilute ammonia; the sealing temperature is kept constant at 40℃, and the total sealing time is 20 minutes; the ultrasonic equipment is used throughout the process, with an ultrasonic frequency of 20kHz and a power density of 0.3W / cm³. 2 The sealing solution is filtered through a 0.22μm filter element at a constant temperature to continuously remove trace impurities from the system. After sealing, the profile is removed and rinsed with three levels of pure water.

[0045] S4 fluorosilane hydrophobic modification treatment: Low-temperature drying: Place the profile in an oven at 60℃ for 8 minutes until the surface is completely dry; Preparation and hydrolysis of modified solution: 1 wt% perfluorooctyltriethoxysilane was added, and the volume ratio of solvent ethanol to deionized water was 80:20; 0.1 wt% glacial acetic acid was added, and the solution was sealed and allowed to stand at room temperature for 30 min for hydrolysis. Room temperature impregnation: The profile is completely immersed in the modified liquid and removed after immersion at a constant temperature for 5 minutes; Segmented gradient curing: Pre-curing at 80℃ for 10 minutes, then heating to 90℃ and maintaining a constant temperature for 10 minutes; relative humidity of the curing environment controlled at 40%.

[0046] After S5 post-treatment curing, the profile is thoroughly rinsed with pure water and dried in a 110℃ constant temperature oven for 15 minutes. After drying, the surface moisture content of the profile is tested to be ≤0.5%, and the finished outdoor corrosion-resistant aluminum alloy profile is obtained. Example 2:

[0047] S1 profile pretreatment: Alkaline degreasing: Sodium carbonate-trisodium phosphate composite degreasing bath, temperature 60℃, profile continuously immersed for 12 minutes; Alkaline etching: 60 g / L sodium hydroxide aqueous solution, bath temperature 50℃, immersion of profiles for 5 min; Acid neutralization: Neutralize by soaking in a 15 g / L dilute sulfuric acid solution for 3 minutes; Multi-stage pure water washing: Three stages of ambient temperature flowing pure water rinsing, with each stage lasting 2 minutes, thoroughly rinsing away residual chemicals from the profile surface.

[0048] S2 Sulfuric Acid Anodizing Treatment: Prepare a sulfuric acid electrolyte with a sulfuric acid concentration of 180 g / L; maintain a constant temperature of 22℃ in the oxidation tank; use a profile as the anode and a pure lead plate as the cathode; anode current density is 1.8 A / dm³. 2 The working voltage is 18V, and the oxidation is carried out for 50 minutes to form a uniform γ-Al2O3 oxide film on the surface of the profile. After removal, the profile is rinsed with three-stage pure water and the surface is kept moist.

[0049] S3 Rare Earth-Silane Hybrid Ultrasonic-Assisted Sealing Treatment: Step 1: Preparation of Sealing Solution B1 Silane Pre-hydrolysis: 5g of silane coupling agent KH-560 was measured and added to deionized water (20% of the total mass of the silane formulation). Glacial acetic acid was added dropwise to adjust the pH to 4.5. The mixture was magnetically stirred at 350 rpm and hydrolyzed at room temperature under sealed conditions for 60 minutes to obtain a transparent silane sol. B2 Cerium Salt Complexation Modification: 8g of cerium nitrate hexahydrate was measured and added to the remaining deionized water. EDTA-2Na was added, and EDTA-2Na reacted with Ce... 3+ The molar ratio was 0.5:1; the system temperature was 30℃, and the mixture was stirred continuously for 20 min until the solid was completely dissolved to obtain a cerium salt aqueous solution. B3 hybrid compound was mixed thoroughly: the cerium salt aqueous solution was added dropwise to the silane sol at a uniform rate of 4 mL / min, with 1.5 g of hexamethylenetetramine added simultaneously; the mixture was stirred at a constant temperature of 400 r / min for 30 min; the pH of the system was adjusted to 6.5 with dilute ammonia, and the mixture was allowed to stand for 15 min to defoam; deionized water was then added to a final volume of 1 L to obtain the finished sealing solution.

[0050] The second step, sealing, involves completely immersing the profile in the sealing solution, maintaining the pH of the solution at 6.5 with dilute ammonia; the sealing temperature is kept constant at 55℃, and the total sealing time is 40 minutes; the ultrasonic equipment is used throughout the process, with an ultrasonic frequency of 28kHz and a power density of 0.5W / cm³. 2 The sealing solution is filtered through a 0.22μm filter element at a constant temperature to continuously remove trace impurities from the system. After sealing, the profile is removed and rinsed with three levels of pure water.

[0051] S4 fluorosilane hydrophobic modification treatment: Low-temperature drying: Place the profile in an oven at 70℃ and dry for 10 minutes until the surface is completely dry; Preparation and hydrolysis of modified solution: 3 wt% perfluorooctyltriethoxysilane was added, and the volume ratio of solvent ethanol to deionized water was 80:20; 0.1 wt% glacial acetic acid was added, and the solution was sealed and allowed to stand at room temperature for 40 min for hydrolysis. Room temperature impregnation: The profile is completely immersed in the modified liquid and removed after being impregnated at a constant temperature for 10 minutes; Segmented gradient curing: Pre-curing at 80℃ for 10 minutes, then heating to 100℃ and maintaining a constant temperature for 20 minutes; relative humidity of the curing environment controlled at 60%.

[0052] After S5 post-treatment curing, the profile is thoroughly rinsed with pure water and dried in a 120℃ constant temperature oven for 20 minutes. After drying, the surface moisture content of the profile is tested to be ≤0.5%, and the finished outdoor corrosion-resistant aluminum alloy profile is obtained. Example 3:

[0053] S1 profile pretreatment: Alkaline degreasing: Sodium carbonate-trisodium phosphate composite degreasing bath solution, temperature 55℃, profile continuously immersed for 10 minutes; Alkaline etching: 55 g / L sodium hydroxide aqueous solution, bath temperature 48℃, profile immersion for 4 min; Acid neutralization: Neutralize soaking in a 12 g / L dilute sulfuric acid aqueous solution for 2.5 min; Multi-stage pure water washing: Three stages of ambient temperature flowing pure water rinsing, with each stage lasting 2 minutes, thoroughly rinsing away residual chemicals from the profile surface.

[0054] S2 sulfuric acid anodizing treatment: Sulfuric acid electrolyte was prepared with a sulfuric acid concentration of 165 g / L; the oxidation tank was kept at a constant temperature of 18℃; a profile was used as the anode, and a pure lead plate was used as the cathode; the anode current density was 1.5 A / dm³. 2 The working voltage is 16V, and the oxidation is carried out for 40 minutes to form a uniform γ-Al2O3 oxide film on the surface of the profile. After removal, the profile is rinsed with three-stage pure water and the surface is kept moist.

[0055] S3 Rare Earth-Silane Hybrid Ultrasonic-Assisted Sealing Treatment: Step 1: Preparation of Sealing Solution B1 Silane Pre-hydrolysis: 3.5 g of silane coupling agent KH-560 was metered and added to deionized water (20% of the total silane mass). Glacial acetic acid was added dropwise to adjust the pH to 4.2. The mixture was magnetically stirred at 300 r / min and hydrolyzed at room temperature under sealed conditions for 45 min to obtain a transparent silane sol. B2 Cerium Salt Complexation Modification: 5.5 g of cerium nitrate hexahydrate was metered and added to the remaining deionized water. EDTA-2Na was added, and EDTA-2Na reacted with Ce... 3+ The molar ratio was 0.35:1; the system temperature was 22℃, and the mixture was stirred continuously for 18 min until the solid was completely dissolved to obtain a cerium salt aqueous solution. B3 hybrid compound was mixed thoroughly: the cerium salt aqueous solution was added dropwise to the silane sol at a uniform rate of 3 mL / min, with 1.0 g of hexamethylenetetramine added simultaneously; the mixture was stirred at a constant temperature of 350 r / min for 25 min; the pH of the system was adjusted to 6.0 with dilute ammonia, and the mixture was allowed to stand for 12 min to defoam. Deionized water was then added to a final volume of 1 L to obtain the finished sealing solution.

[0056] The second step, sealing, involves completely immersing the profile in the sealing solution, maintaining the pH of the solution at 6.0 with dilute ammonia; the sealing temperature is kept constant at 48℃, and the total sealing time is 30 minutes; the ultrasonic equipment is used throughout the process, with an ultrasonic frequency of 24kHz and a power density of 0.4W / cm³. 2 The sealing solution is filtered through a 0.22μm filter element at a constant temperature to continuously remove trace impurities from the system. After sealing, the profile is removed and rinsed with three levels of pure water.

[0057] S4 fluorosilane hydrophobic modification treatment: Low-temperature drying: Place the profile in an oven at 65℃ for 9 minutes until the surface is completely dry; Preparation and hydrolysis of modified solution: 2 wt% perfluorooctyltriethoxysilane was added, and the volume ratio of solvent ethanol to deionized water was 80:20; 0.1 wt% glacial acetic acid was added, and the solution was sealed and allowed to stand at room temperature for 35 min for hydrolysis. Room temperature impregnation: The profile is completely immersed in the modified liquid and removed after 7 minutes of constant temperature impregnation; Segmented gradient curing: Pre-curing at 80℃ for 10 minutes, then heating to 95℃ and maintaining a constant temperature for 15 minutes; relative humidity of the curing environment controlled at 50%.

[0058] After S5 post-treatment curing, the profile is thoroughly rinsed with pure water and dried in a 115℃ constant temperature oven for 18 minutes. After drying, the surface moisture content of the profile is tested to be ≤0.5%, thus obtaining the finished outdoor corrosion-resistant aluminum alloy profile.

[0059] Comparative Example 1: All steps S1, S2, S3, S4, and S5 were performed in their entirety, with temperature, duration, current, ultrasonic treatment, and modification / curing parameters all consistent with those in Example 3. The only difference was that cerium nitrate hexahydrate was omitted when preparing the sealing solution; the amounts of silane and hexamethylenetetramine remained unchanged; the other sealing solution preparation steps were identical. The rare-earth cerium ion passivation system was absent, and the oxide film pores were sealed solely by silane organic compounds.

[0060] Comparative Example 2: All processes, bath formulations, and modified curing parameters are exactly the same as in Example 3; only the ultrasonic device is not turned on in the rare earth silane sealing process, and the sealing is completed by static immersion only, without ultrasonic enhancement of micropore filling effect.

[0061] Comparative Example 3: All steps S1, S2, and S3 are performed in their entirety, with process parameters and sealing liquid formulation remaining consistent with those in Example 3. The fluorosilane impregnation and gradient curing steps are skipped, and the material is directly processed into S5 drying after sealing and washing. The profile surface has no low surface energy hydrophobic protective layer.

[0062] Comparative Example 4: The pretreatment process parameters for S1 are completely consistent with those in Example 3; The S2 anodic oxidation electrolyte, temperature, current, and oxidation time are the same as in Example 3; The sealing agent is a commercially available standard nickel-cobalt salt sealant, which is statically immersed at room temperature for 25 minutes without rare earth silane or ultrasonic assistance. Without setting a fluorosilane hydrophobic modification process, the sample was directly dried at 115℃ for 18 minutes after sealing and washing, serving as a standard industry control sample.

[0063] test: Each group of samples used a 100mm×50mm×2mm 6063 aluminum profile, with 3 parallel samples per group, and the test results were taken as the arithmetic mean.

[0064] Experiment 1: Neutral Salt Spray Corrosion Performance Test 1.1 Experimental Objective: The resistance of the anodic oxide composite film to chloride ion corrosion of each group of samples was compared. The duration of continuous spraying until the first visible pitted white corrosion spots appeared on the sample surface was used as the evaluation index to verify the synergistic anti-corrosion effect of the rare earth cerium passivation, ultrasonic sealing and fluorosilane hydrophobic three-layer protection system.

[0065] 1.2 Experimental Instruments and Reagents: Instruments: Neutral salt spray test chamber, digital display constant temperature oven, stereomicroscope, electronic balance; Reagents: Industrial grade sodium chloride, deionized water; 1.3 Test Methods: Prepare a 5% sodium chloride test solution and adjust the pH of the solution to 6.5–7.2 using dilute sodium hydroxide / dilute hydrochloric acid; Sample pretreatment: Grind off the burrs on all four sides of the profile. The back and cut surfaces of the sample are completely covered and sealed with neutral high-temperature resistant silicone sealant, leaving only the front intact modified film layer as the test surface. The sealant is allowed to cure at room temperature for 24 hours before being put into the test. Salt spray chamber parameter settings: constant temperature 35℃, continuous spray mode, salt spray deposition rate controlled at 1-2 mL / 80 cm. 2 • h; The sample should be placed at a 30° angle to avoid prolonged immersion of the local surface in liquid. Observation record: The sample surface was observed every 4 hours using a stereomicroscope, and the time when the first white alumina corrosion spots appeared was recorded; if no corrosion spots were found after 1500 hours, the observation period was extended to 2000 hours; Parallel test: Three samples in each group were tested simultaneously, and the average corrosion initiation time was taken as the final data.

[0066] 1.4 Experimental Data: Table 1. Average time to first appearance of corrosion spots. Example 1 1820 Example 2 2080 Example 3 1950 Comparative Example 1 710 Comparative Example 2 1090 Comparative Example 3 1280 Comparative Example 4 430 The salt spray resistance time of the three sets of examples was significantly longer than that of all comparative examples; Comparative Example 3 and Comparative Example 1: After removing rare earth cerium salts, the corrosion time decreased from 1950 h to 710 h. 3+ Slow hydrolysis within the micropores of the oxide film generates a cerium oxide passivation film, which blocks the pores and inhibits the electrochemical corrosion of the aluminum substrate; silane organic films alone cannot achieve long-term micropore sealing, and chloride ions can easily penetrate the film layer and cause pitting corrosion. Comparative Example 3 and Comparative Example 2: The corrosion time without ultrasonic assistance was reduced to 1090 h. During static immersion, air bubbles were trapped in the oxide micropores, hindering the entry of silane-cerium components into the pores; ultrasonic cavitation can break up the bubbles and enhance liquid penetration, achieving complete sealing of the micropores inside and out; without ultrasonic treatment, only the film is formed on the surface, and defects exist inside the pores, making it easy for corrosive media to penetrate inward; Comparative Example 3 and Comparative Example 3: The corrosion time was reduced to 1280 hours due to the absence of the fluorosilane hydrophobic layer. The fluorosilane film has extremely low surface energy, which significantly reduces the wetting and adsorption of salt droplets on the profile surface and reduces the contact between chloride ions, water vapor and oxide film; relying solely on the sealing layer cannot prevent the continuous adsorption of salt spray, and the risk of corrosion under long-term spraying increases significantly. Comparative Example 4, the traditional nickel-cobalt sealing sample, exhibited the worst corrosion resistance, showing white corrosion spots after only 430 hours. Traditional inorganic nickel salt sealing lacks an organic hydrophobic layer and a rare earth passivation barrier, resulting in limited pore-blocking effectiveness and making it highly susceptible to failure under outdoor salt spray conditions.

[0067] Experiment 2: UV accelerated aging and weather resistance test 2.1 Experimental Objective: The weather resistance performance is evaluated by the degree of gloss decay of the film layer after UV aging, simulating a long-term outdoor sun exposure environment. The lower the gloss loss rate, the stronger the film layer's resistance to photodegradation and chalking.

[0068] 2.2 Test Instruments: Instruments: UVB accelerated aging test chamber, 60° portable gloss meter, dust-free wiping cloth; 2.3 Test Methods: The aging chamber is equipped with UVB-313 ultraviolet lamps with an irradiance of 0.63W / m². 2 Standard cycle: 8 hours of UV irradiation (60℃), 4 hours of condensation and humidification (50℃), 12 hours per cycle, total aging cycle 1000 hours; Before aging, wipe the sample surface with a dust-free ethanol cloth, and after standing and drying, measure the initial gloss value of 60° for each group of samples. Take 5 points for each sample to calculate the average gloss. After completing 1000 hours of cyclic aging, the sample was wiped under the same conditions, and the average gloss value at 60° was measured again. The formula for calculating gloss loss rate is: Gloss loss rate = (Average gloss value before aging - Average gloss value after aging) ÷ Average gloss value before aging × 100%; the results of 3 samples in each group are taken as the arithmetic mean.

[0069] 2.4 Experimental Data: Table 21000h UV aging average light loss rate Example 1 3.4 Example 2 2.3 Example 3 2.8 Comparative Example 1 13.1 Comparative Example 2 9.2 Comparative Example 3 7.8 Comparative Example 4 18.7 The gloss loss rate of all three sets of examples was less than 3.4%, and the gloss retention of the film layer was excellent after ultraviolet aging, which can meet the long-term exposure conditions of outdoor curtain walls and photovoltaic profiles. Comparative Example 1, without rare earth cerium salts, showed a significant increase in gloss loss rate to 13.1%. Trivalent cerium possesses an ultraviolet absorption and shielding effect, which can prevent ultraviolet light from directly damaging the silane organic chain segments; without cerium components, the silane organic film is prone to photo-oxidative decomposition, resulting in surface gloss loss and slight powdering; Comparative Example 2 lacks ultrasonic sealing, resulting in incomplete sealing of oxide micropores. Ultraviolet light and moisture can penetrate the pores and erode the interface between the film and the aluminum substrate, leading to a decrease in interfacial bonding strength and an accelerated rate of gloss decay. In Comparative Example 3, the fluorine-free silane hydrophobic layer experienced continuous water vapor penetration into the membrane during the aging and condensation stage, which accelerated the hydrolytic aging of the organosilane and significantly increased the degree of gloss loss. Traditional nickel-cobalt sealing comparative example 4 lacks an organic hybrid protective layer. The inorganic sealing layer itself has no UV shielding capability. After long-term UV irradiation, the film layer cracks and pulverizes severely, resulting in the highest light loss rate.

[0070] Experiment 3: Hydrophobicity test of surface static water contact angle: 3.1 Experimental Objective: The test profiles are evaluated for their hydrophobicity. A higher static water contact angle indicates better surface hydrophobicity, resistance to salt spray adhesion, and resistance to outdoor dirt accumulation. The test also distinguishes the decisive role of the fluorosilane modification process in surface wetting properties.

[0071] 3.2 Experimental Instruments and Reagents: Instruments: Optical contact angle meter; Reagents: High-purity deionized water; 3.3 Test Methods: Sample pretreatment: Wipe the film surface with anhydrous ethanol, let it stand and dry in a dust-free environment at room temperature for 30 minutes to remove surface oil and dust interference; Measurement operation: The instrument quantitatively adds 5 μL of deionized water to the flat film area, the camera captures the droplet profile, and the software automatically calculates the static contact angle; Five non-overlapping flat areas were selected for testing on each sample. The average value of each sample was taken, and the average contact angle of each group of three samples was obtained by summing the results.

[0072] 3.4 Experimental Data: Table 3 Example 1 115.8 Example 2 121.9 Example 3 118.5 Comparative Example 1 117.6 Comparative Example 2 116.8 Comparative Example 3 61.7 Comparative Example 4 57.5 Examples 1, 2, and 3 all underwent hydrophobic modification with fluorosilane, and the contact angles were all higher than 115°, which are strong hydrophobic surfaces. Comparative Examples 1 and 2 fully retained the fluorosilane modification process, only lacking the core components of the sealing stage. The contact angles were very similar to those of the examples, proving that rare earth cerium salts and ultrasonic sealing only act on the sealing of pores inside the film layer and do not directly change the hydrophobic wetting properties of the profile surface. After the fluorosilane modification was removed in Comparative Example 3, the contact angle dropped sharply to 61.7°, which is only a weakly hydrophilic surface. Moisture and salt droplets can easily spread and be adsorbed on the surface of the profile, which greatly increases the risk of long-term outdoor corrosion. Traditional nickel-cobalt sealing comparison example 4 has no organic low surface energy coating, the lowest contact angle, and the surface is extremely prone to adsorbing water vapor and salt, resulting in significantly accelerated corrosion and aging during outdoor service.

[0073] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A corrosion-resistant treatment process for outdoor aluminum alloy profiles, characterized in that, The following steps are performed sequentially: S1. Profile Pretreatment: Outdoor aluminum alloy profiles of grade 6061 or 6063 are subjected to alkaline degreasing, alkaline etching, acid neutralization, and multi-stage flowing pure water washing in sequence. The alkaline degreasing uses a sodium carbonate-trisodium phosphate composite degreasing system, with a degreasing temperature of 50-60℃ and a degreasing time of 8-12 minutes. The alkaline etching uses a sodium hydroxide aqueous solution with a mass concentration of 50-60 g / L, with an alkaline etching temperature of 45-50℃ and an alkaline etching time of 3-5 minutes. The acid neutralization uses a dilute sulfuric acid aqueous solution with a mass concentration of 10-15 g / L and a neutralization time of 2-3 minutes. S2. Sulfuric Acid Anodizing Treatment: Using the previously treated and dried aluminum alloy profile as the anode, DC anodizing treatment is performed using a sulfuric acid aqueous solution electrolyte. The sulfuric acid mass concentration in the electrolyte is 150–180 g / L, the oxidation tank temperature is 15–22℃, and the anode current density is 1.2–1.8 A / dm³. 2 The oxidation working voltage is 14-18V, the oxidation time is 30-50min, and finally a γ-Al2O3 anodic oxide film is uniformly generated on the outer surface of the profile. S3. Rare Earth-Silane Hybrid Ultrasonic-Assisted Sealing Treatment: The profile, after anodizing and rinsing with pure water while maintaining a moist surface, is completely immersed in a prepared rare earth-silane hybrid sealing solution for constant-temperature sealing. The pH of the sealing solution is precisely adjusted to 5.5–6.5 using dilute ammonia. The sealing temperature is maintained at 40–55℃, and the total sealing time is 20–40 minutes. The entire sealing process utilizes a frequency of 20–28 kHz and a power density of 0.3–0.5 W / cm². 2 Low-frequency continuous ultrasonic-assisted dispersion; the sealing liquid is uniformly prepared by a stepwise preparation process of silane pre-hydrolysis and cerium salt complexation slow release; S4. Fluorosilane hydrophobic modification treatment: After rinsing the sealed profile with pure water to remove residual sealing liquid, place it at 60-70℃ for low-temperature drying for 8-10 minutes. After the profile surface is completely dry, immerse it in a mixed modification solution of perfluorooctyltriethoxysilane that has been fully hydrolyzed by acid catalysis and immerse it at room temperature for 5-10 minutes. After immersion, take out the profile and use a segmented gradient temperature curing method to cure it, forming a low surface energy hydrophobic protective layer on the surface of the anodic oxide film. S5. Post-treatment: After the cured profile is thoroughly rinsed with pure water, it is placed in a constant temperature drying equipment at 110-120℃ and dried for 15-20 minutes. After drying, the surface moisture content of the profile is controlled to be ≤0.5%, and finally outdoor aluminum alloy profiles are obtained.

2. The corrosion-resistant treatment process for outdoor aluminum alloy profiles according to claim 1, characterized in that, The sealing solution in step S3 consists of the following components by mass concentration: cerium nitrate hexahydrate 3-8 g / L, silane coupling agent KH-560 2-5 g / L, hexamethylenetetramine 0.5-1.5 g / L, and the balance is deionized water.

3. The corrosion-resistant treatment process for outdoor aluminum alloy profiles according to claim 2, characterized in that, The preparation process of the rare earth-silane hybrid sealing solution specifically includes the following sequential operation steps: B1. Silane pre-hydrolysis: Take the silane coupling agent KH-560 according to the formula, add it to 20% of the corresponding mass of deionized water, add glacial acetic acid dropwise to adjust the pH of the system to 4.0-4.5, and continuously stir magnetically at room temperature for 30-60 minutes to obtain pre-hydrolyzed silane sol. B2. Cerium salt complexation modification: Take cerium nitrate hexahydrate according to the formula, add it to the remaining proportion of deionized water, add cerium ion slow-release complexing agent, and continue stirring until the solid is completely dissolved to prepare a cerium salt aqueous solution. B3. Hybridization and Mixing: The cerium salt aqueous solution prepared in step B2 is slowly added dropwise at a uniform rate of 2-4 mL / min to the pre-hydrolyzed silane sol prepared in step B1, and a measured amount of hexamethylenetetramine is added simultaneously. The mixture is stirred continuously at a constant temperature and speed of 300-400 r / min for 20-30 min. After stirring, the pH value of the system is precisely adjusted to 5.5-6.5 with dilute ammonia water. The mixture is allowed to stand for 10-15 min to remove bubbles and small air bubbles, thus obtaining the finished rare earth-silane hybrid sealing solution.

4. The corrosion-resistant treatment process for outdoor aluminum alloy profiles according to claim 2, characterized in that, During the silane pre-hydrolysis process in step B1, the magnetic stirring speed is kept constant at 250–350 r / min.

5. The corrosion-resistant treatment process for outdoor aluminum alloy profiles according to claim 2, characterized in that, In step B2, the cerium ion slow-release complexing agent is EDTA-2Na; wherein, EDTA-2Na reacts with Ce in the solution. 3+ The molar ratio is 0.2 to 0.5:

1.

6. The corrosion-resistant treatment process for outdoor aluminum alloy profiles according to claim 2, characterized in that, In step B2, during the cerium salt complexation modification process, the system dissolution temperature is controlled at 15–30°C, and the continuous stirring dissolution time is 15–20 min.

7. The corrosion-resistant treatment process for outdoor aluminum alloy profiles according to claim 1, characterized in that, Throughout the sealing process in step S3, the sealing solution adopts a constant temperature circulating filtration mode with a filtration accuracy of 0.22μm.

8. The corrosion-resistant treatment process for outdoor aluminum alloy profiles according to claim 1, characterized in that, The specific formulation of the perfluorooctyltriethoxysilane mixed modification solution in step S4 is as follows: the amount of perfluorooctyltriethoxysilane added is 1-3 wt%, and the solvent is a mixture of ethanol and deionized water, wherein the volume ratio of ethanol to deionized water is 80:

20.

9. The corrosion-resistant treatment process for outdoor aluminum alloy profiles according to claim 1, characterized in that, Before the modified solution is used, it needs to undergo acid-catalyzed hydrolysis pretreatment: add 0.1 wt% glacial acetic acid to the prepared modified solution and let it stand at room temperature for 30-40 minutes for hydrolysis.

10. The corrosion-resistant treatment process for outdoor aluminum alloy profiles according to claim 1, characterized in that, The specific operating parameters of the segmented gradient temperature curing process described in step S4 are as follows: First, pre-curing at 80℃ for 10 minutes to complete the initial cross-linking and shaping, then heating to 90-100℃ for constant temperature curing for 10-20 minutes; the relative humidity of the environment during the entire curing process is controlled at 40%-60%.

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