A multi self-repairing anticorrosive and antifouling coating and a preparation method thereof

Abstract

This invention discloses a multi-layer self-healing anti-corrosion and anti-fouling coating and its preparation method. The method uses hollow cerium dioxide as a nano-container to load a benzotriazole corrosion inhibitor and a 4,5-dichloro-2-n-octyl-3-isothiazolinone antifouling agent. The surface of the cerium dioxide loading mixture is then modified with silane acrylate, significantly improving the particle dispersibility in the acrylic composite coating. Finally, it is polymerized with acrylic acid and methyl methacrylate to prepare the multi-layer self-healing anti-corrosion and antifouling coating. Furthermore, constant current co-deposition further enhances the effect. The resulting coating possesses excellent anti-corrosion and antifouling properties, providing long-term protection for various metal materials and extending their service life.

Description

Technical Field

[0001] This invention belongs to the field of functional materials technology, specifically relating to a multi-layer self-healing anti-corrosion and anti-fouling coating and its preparation method. Background Technology

[0002] Developing coatings with both superhydrophobic and self-healing properties based on the "lotus effect" and intelligent protection mechanisms is a current direction in coating development. For example, patent document CN115651533A discloses a method for preparing a superhydrophobic self-healing silane coating. Hollow cerium dioxide is used as a nano-container to load a benzotriazole corrosion inhibitor, which is then mixed with bissilane and hydrolyzed on a metal surface to obtain a superhydrophobic self-healing coating. The coating can form a rough micro-nano structure on the metal substrate surface through the hydrolysis of bissilane, thus giving the coating both superhydrophobic and self-healing properties.

[0003] However, during the actual research and development process, the inventors discovered that by further optimizing the composition of the hollow cerium dioxide load and improving the coating preparation method, a more uniform and dense anti-corrosion and anti-fouling coating can be prepared. Compared with the superhydrophobic self-healing silane coating disclosed in the prior art CN115651533A, it has a more significant anti-corrosion effect and outstanding anti-fouling performance. Summary of the Invention

[0004] Therefore, based on the prior application, and through improvements, this invention proposes a multi-layer self-healing anti-corrosion and anti-fouling coating and its preparation method. The resulting coating has excellent anti-corrosion and anti-fouling properties and can be applied to corrosion protection and anti-fouling of various metal materials.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: This invention provides a multi-layer self-healing anti-corrosion and anti-fouling coating and its preparation method, comprising the following steps: S1. Prepare hollow cerium dioxide nanoparticles; S2. Load the hollow cerium dioxide from step S1 with a mixture, the mixture being composed of a corrosion inhibitor and an antifouling agent, to obtain cerium dioxide nanoparticles loaded with the mixture. S3. Immerse the cerium dioxide nanoparticles of the loaded mixture obtained in step S2 into an organic solvent containing vinyltrimethoxysilane to prepare vinyltrimethoxysilane modified cerium dioxide nanoparticles. S4. Acrylic acid, methyl methacrylate and vinyltrimethoxysilane-modified cerium dioxide nanoparticles obtained in step S3 are mixed evenly and polymerized on the metal surface to be coated by electrochemical polymerization to form the multi-layer self-healing anti-corrosion and anti-fouling coating. Alternatively, acrylic acid, methyl methacrylate, and the vinyltrimethoxysilane-modified cerium dioxide nanoparticles obtained in step S3 can be mixed evenly and prepared by free radical solution polymerization to obtain an acrylic composite resin. The resulting composite can then be sprayed onto the metal surface to be coated to form the aforementioned multi-layer self-healing anti-corrosion and anti-fouling coating.

[0006] In the coating preparation method of the present invention, hollow cerium dioxide nanoparticles are used as nanocontainers to simultaneously load corrosion inhibitors and antifouling agents. On the other hand, by modifying the surface of the hollow cerium dioxide nanoparticles loaded with corrosion inhibitors and antifouling agents with vinyltrimethoxysilane, the dispersibility of the particles in the acrylic composite coating can be significantly improved, thereby preparing a more uniform and dense anti-corrosion and antifouling coating.

[0007] Preferably, in step S1, the hollow cerium dioxide nanoparticles are prepared by the following method: dissolving silica nanoparticles in an organic solvent, dissolving cerium nitrate hexahydrate in water, combining the two solutions, reacting at 120-150℃ for 20-24h, and annealing the reaction product at 450-550℃ to obtain hollow cerium dioxide nanoparticles.

[0008] Preferably, in step S1, the particle size of the silica nanoparticles is 300-500 nm, and the concentration of the silica nanoparticles in the organic solvent is 2-5 g / 50 mL.

[0009] Preferably, in step S1, the concentration of the cerium nitrate hexahydrate in water is 1-1.5 g / 5 mL.

[0010] Preferably, in step S1, the organic solvent used to dissolve the silica nanoparticles includes ethylene glycol.

[0011] Preferably, in step S2, the corrosion inhibitor is benzotriazole and the antifouling agent is 4,5-dichloro-2-n-octyl-3-isothiazolinone.

[0012] Preferably, in step S2, the mass ratio of the corrosion inhibitor to the antifouling agent is 3-1:1-3.

[0013] Preferably, in step S2, the hollow cerium dioxide from step S1 is dissolved in a mixed solvent of anhydrous ethanol and deionized water, and then a corrosion inhibitor and an antifouling agent are added respectively. After complete dissolution, the corrosion inhibitor is ensured to have the maximum loading in the hollow cerium dioxide by vacuuming and ultrasonic operation. Finally, the hollow cerium dioxide nanoparticles with the loaded mixture are obtained by centrifugation and drying.

[0014] Preferably, in step S2, the concentration of the hollow cerium dioxide in the mixed solvent is 1-1.5 g / 50 mL, and the concentration of the mixture in the mixed solvent is 0.5-1 g / 50 mL.

[0015] Preferably, the vacuum-ultrasonic operation involves vacuuming for 15-20 minutes, releasing the air to the room's atmospheric pressure, and then ultrasonicating for 30-45 minutes. This operation is repeated 5-7 times.

[0016] Preferably, in step S3, surface modification is performed using a vinyltrimethoxysilane / anhydrous ethanol solution at a volume ratio of 0.5-2%. This can be achieved by immersing cerium dioxide nanoparticles loaded with the mixture in the vinyltrimethoxysilane / anhydrous ethanol solution for 1-3 hours, followed by drying. The drying temperature is typically 30-60°C, such as 30°C, 40°C, 50°C, or 60°C.

[0017] In step S4, the coating can be formed by uniformly mixing acrylic acid, methyl methacrylate, and the vinyltrimethoxysilane-modified cerium dioxide nanoparticles obtained in step S3, first synthesizing an acrylic resin through free radical solution polymerization, and then spraying the composite of the acrylic resin mixed with vinyltrimethoxysilane-modified cerium dioxide nanoparticles onto the metal surface to be coated; alternatively, acrylic acid, methyl methacrylate, and the vinyltrimethoxysilane-modified cerium dioxide nanoparticles obtained in step S3 can be uniformly mixed and directly polymerized on the metal surface to be coated through electrochemical polymerization. This results in a denser coating, stronger adhesion to the substrate, and superior performance. Preferably, in step S4, constant current electrochemical polymerization is used to co-deposit the coating on the surface of the metal substrate to be coated, resulting in a denser coating and higher bonding strength.

[0018] Preferably, in step S4, the mass ratio of acrylic acid, methyl methacrylate and vinyltrimethoxysilane modified cerium dioxide nanoparticles is 45-55:45-55:1-3.

[0019] Preferably, a constant current of 0.3-0.8 mA / cm is used. 2 The polymerization time is 20-40 minutes.

[0020] Preferably, the metal substrate undergoes pretreatment before coating, including polishing and cleaning. For example, in some embodiments, it may first be polished sequentially with sandpaper of different grits to remove surface impurities and oxides, and then ultrasonically cleaned in an organic solvent to remove surface organic matter. The organic solvent may be ethanol, acetone, etc.

[0021] Preferably, the metal substrate to be coated includes, but is not limited to, low-carbon steel substrate, aluminum alloy substrate, and copper-nickel alloy substrate.

[0022] In a second aspect, the present invention provides a multi-layer self-healing anti-corrosion and anti-fouling coating prepared by the above method. This coating can be applied to the protection and anti-fouling of various metal materials in corrosive media, thereby extending their service life in corrosive media.

[0023] Compared with the prior art, the beneficial effects of the present invention are: This invention discloses a multi-layer self-healing anti-corrosion and anti-fouling coating and its preparation method. Hollow cerium dioxide is used as a nano-container to load a benzotriazole corrosion inhibitor and a 4,5-dichloro-2-n-octyl-3-isothiazolinone antifouling agent. The surface of the cerium dioxide loading mixture is then modified with silane acrylate, significantly improving the dispersion of particles in the acrylic composite coating. Finally, it is polymerized with acrylic acid and methyl methacrylate to prepare the multi-layer self-healing anti-corrosion and antifouling coating. Furthermore, constant current co-deposition further enhances the effect. The resulting coating exhibits excellent anti-corrosion and antifouling properties, providing long-term protection for various metal materials and extending their service life. In addition, the preparation method of this invention is simple, reproducible, and the formulation is non-toxic and pollution-free, making it suitable for large-scale industrial applications. Attached Figure Description

[0024] Figure 1 SEM image of hollow cerium dioxide nanoparticles; Figure 2 TEM image of hollow cerium dioxide nanoparticles; Figure 3 TEM image of CeO2 loaded with a mixture of benzotriazole and 4,5-dichloro-2-n-octyl-3-isothiazolinone; Figure 4 A schematic diagram of differential thermal analysis before and after loading a mixture of benzotriazole and 4,5-dichloro-2-n-octyl-3-isothiazolinone onto hollow cerium dioxide nanoparticles; Figure 5 The coating contact angle measurement diagrams for Examples 1-2 are shown. Figure 6 Images of coating samples from Examples 1-1 and 1-2; Figure 7 Electrochemical impedance spectroscopy results of untreated aluminum alloy substrates and coatings from Examples 2-1, 2-2, and Comparative Example 2 in a 3.5% NaCl solution corrosive medium. Figure 8 The electrochemical impedance spectroscopy results are shown for the coatings of Examples 2-2 and Comparative Example 2 after immersion in a 3.5% NaCl solution corrosive medium for 240 hours. Figure 9 The electrochemical impedance spectroscopy results are shown for the coatings of Example 3 and Comparative Example 3 after being scratched and immersed in a 3.5% NaCl solution corrosive medium for 0.5 h and 12 h. Figure 10 The results show the antifouling performance of the aluminum alloy surface coatings in simulated seawater for Examples 2-2 and Comparative Example 2. Detailed Implementation

[0025] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0026] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0027] Example 1-1 A multi-layer self-healing anti-corrosion and anti-fouling coating and its preparation method The method for preparing this anti-corrosion and anti-fouling coating includes the following steps: (1) Preparation of hollow cerium dioxide: Two g of silica nanoparticles with a particle size of 300 nm were added to 50 mL of ethylene glycol and sonicated (900 W) for half an hour. Separately, 1 g of cerium nitrate hexahydrate was dissolved in 5 mL of deionized water. The two liquids were mixed and placed in a vacuum autoclave, reacting at 120 °C for 24 h. After the reaction, the autoclave was cooled to room temperature, and the product was washed five times each with deionized water and anhydrous ethanol. The product was then collected by centrifugation and washed five times each with deionized water and anhydrous ethanol. The precipitate was dried at 80 °C for 4 h. A 4 mol / L sodium hydroxide solution was used to etch a silica template, which was allowed to stand at room temperature for 2 days. The resulting solution was collected by centrifugation, washed five times each with ethanol and deionized water, and dried. Finally, the product was annealed in a muffle furnace at 450 °C for 2 h to obtain hollow cerium dioxide nanoparticles. The prepared hollow cerium dioxide nanoparticles were tested by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the results are shown below. Figure 1 and 2 As shown, this indicates that the cerium dioxide nanoparticles prepared by this step do indeed have a hollow structure.

[0028] (2) Preparation of cerium dioxide nanoparticles loaded with mixture (BTAH / DCOIT@CeO2) 1 g of the hollow cerium dioxide nanoparticles prepared above were added to a mixed solution of 25 mL anhydrous ethanol and 25 mL deionized water and sonicated (900 W) for half an hour. Then, 0.5 g of benzotriazole and 0.5 g of 4,5-dichloro-2-n-octyl-3-isothiazolinone were added, and the mixture was stirred thoroughly until completely dissolved. Sonication was continued for another half hour. After evacuating for 15 minutes, the pressure was released to atmospheric pressure, and sonication was repeated for another half hour. This vacuum-sonication cycle was repeated 5 times to ensure maximum loading of the benzotriazole and 4,5-dichloro-2-n-octyl-3-isothiazolinone mixture in the hollow cerium dioxide nanocontainer. The cerium dioxide nanoparticles loaded with benzotriazole and 4,5-dichloro-2-n-octyl-3-isothiazolinone were then collected by centrifugation and dried in a vacuum drying oven at 50 °C for 2 hours. h, cerium dioxide nanoparticles (BTAH / DCOIT@CeO2) loaded with benzotriazole and 4,5-dichloro-2-n-octyl-3-isothiazolinone were prepared, and their TEM test results are as follows. Figure 3 As shown in the figure. In addition, differential thermal analysis was performed on hollow cerium dioxide before and after loading a mixture of benzotriazole and 4,5-dichloro-2-n-octyl-3-isothiazolinone. The results are shown in the figure. The results show that the mixture has been loaded into the hollow cerium dioxide nanocontainer, and its loading is as high as 22.7%.

[0029] (3) Preparation of vinyltrimethoxysilane modified cerium dioxide nanoparticles (BTAH / DCOIT@CeO2 / silane) Prepare 50 mL of a 1% (v / v) vinyltrimethoxysilane / anhydrous ethanol solution, immerse 0.1 g of cerium dioxide nanoparticles loaded with the mixture in the solution for 2 hours, remove and dry completely at 40 °C to obtain BTAH / DCOIT@CeO2 / silane nanoparticles.

[0030] (4) Pretreatment of low-carbon steel substrate: The low-carbon steel substrate is first polished with 150-grit, 320-grit, 600-grit, 1200-grit and 2000-grit sandpaper to remove impurities and oxides from the surface. Then it is ultrasonically cleaned in anhydrous ethanol and acetone for 20 minutes to remove organic matter from the surface. Finally, it is dried with N2 for later use.

[0031] (5) Preparation of composite coating: Acrylic acid, methyl methacrylate, and BTAH / DCOIT@CeO2 / silane raw materials were prepared in a mass ratio of 50:50:2 and mixed evenly. First, a free radical solution polymerization method was used (referring to the literature "Synthesis of Water-Soluble Hydroxyl Acrylic Resin for Aluminum Coating, Guangdong Chemical Industry, 2018, 45(12): 98-99+124") to polymerize the acrylic acid and methyl methacrylate to form pure acrylic resin. Then, the acrylic resin composite mixed with BTAH / DCOIT@CeO2 / silane particles was sprayed onto the pretreated low-carbon steel surface. After complete curing, a chemically polymerized composite coating was obtained on the low-carbon steel surface. The sample image is shown below. Figure 6 As shown.

[0032] Examples 1-2 Steps (1)-(4) are the same as in Example 1-1.

[0033] Step (5) Preparation of the composite coating: Acrylic acid, methyl methacrylate, and BTAH / DCOIT@CeO2 / silane were mixed evenly at a mass ratio of 50:50:2, and a constant current of 0.5 mA / cm was applied. 2 Electropolymerization was performed on the surface of low-carbon steel for 30 minutes. The sample was then removed and dried at 40℃ for 2 hours to obtain a multi-layer self-healing anti-corrosion and anti-fouling coating. The contact angle of the multi-layer self-healing anti-corrosion and anti-fouling coating on the low-carbon steel surface was measured using a contact angle tester. The results are as follows: Figure 5 As shown, the contact angle is higher than 150°. This embodiment demonstrates a multi-layered self-healing, anti-corrosion, and anti-fouling coating sample constructed on a low-carbon steel surface. Figure 6 As shown.

[0034] Comparative Example 1 The coating preparation method in this comparative example, referring to the method in Example 1 of prior application CN115651533A, includes the following steps: (1) Preparation of hollow cerium dioxide: Same as Example 1-1 (2) Preparation of cerium dioxide nanoparticles loaded with corrosion inhibitor (BTAH@CeO2) 1g of the hollow cerium dioxide nanoparticles prepared above were added to 50mL of anhydrous ethanol and sonicated (900W) for half an hour. Then, 0.5g of benzotriazole was added and stirred thoroughly to dissolve completely. The sonication was continued for another half hour. After vacuuming for 15 minutes, the gas was released to atmospheric pressure and sonicated for another half hour. This vacuuming-sonication operation was repeated 5 times to ensure that the benzotriazole corrosion inhibitor was loaded to the maximum extent in the hollow cerium dioxide nanocontainer. The hollow cerium dioxide nanoparticles loaded with benzotriazole were then collected by centrifugation and dried in a vacuum drying oven at 50℃ for 2 hours to obtain hollow cerium dioxide nanoparticles loaded with benzotriazole with a loading of 20.8%.

[0035] (3) Pretreatment of aluminum alloy substrate: Same as Example 1-1.

[0036] (4) Preparation of composite coating: Anhydrous ethanol, deionized water, hexadecyltrimethoxysilane, and ethyl silicate were mixed evenly in a volume ratio of 75:25:2:2. Acetic acid was added to adjust the pH of the solution to 4. The solution was then hydrolyzed at 35°C for 72 hours. Hollow cerium dioxide nanoparticles loaded with benzotriazole (2 g / 100 mL) were then added. After sonication (900 W) for half an hour, the solution was immersed in a pretreated aluminum alloy substrate for 15 minutes. After washing three times with anhydrous ethanol, the solution was dried in a vacuum drying oven at 100°C for 1 hour to obtain the coating, which also has a contact angle higher than 150°.

[0037] Example 2-1 A multi-layer self-healing anti-corrosion and anti-fouling coating and its preparation method The method for preparing this anti-corrosion and anti-fouling coating includes the following steps: (1) Preparation of hollow cerium dioxide: Five g of 500 nm silica nanoparticles were added to 50 mL of ethylene glycol and sonicated (900 W) for half an hour. Separately, 1.5 g of cerium nitrate hexahydrate was dissolved in 5 mL of deionized water. The two liquids were mixed and placed in a vacuum autoclave, reacting at 150 °C for 24 h. After the reaction, the autoclave was cooled to room temperature, and the product was washed five times each with deionized water and anhydrous ethanol. The product was then collected by centrifugation and washed five times each with deionized water and anhydrous ethanol. The precipitate was dried at 100 °C for 4 h. A 4 mol / L sodium hydroxide solution was used to etch a silica template, which was allowed to stand at room temperature for 2 days. The resulting solution was collected by centrifugation, washed five times each with ethanol and deionized water, and dried. Finally, the product was annealed in a muffle furnace at 550 °C for 2 h to obtain hollow cerium dioxide nanoparticles (which were confirmed to have a hollow structure by SEM and TEM).

[0038] (2) Preparation of cerium dioxide nanoparticles loaded with mixture (BTAH / DCOIT@CeO2) 1.5 g of the hollow cerium dioxide nanoparticles prepared above were added to a mixed solution of 25 mL anhydrous ethanol and 25 mL deionized water and sonicated (900 W) for half an hour. Then, 0.25 g of benzotriazole and 0.75 g of 4,5-dichloro-2-n-octyl-3-isothiazolinone were added, and the mixture was stirred thoroughly until completely dissolved. Sonication continued for another half hour. After evacuating for 20 minutes, the pressure was released to atmospheric pressure, and sonication was repeated for another half hour. This vacuum-sonication cycle was repeated 5 times to ensure maximum loading of the benzotriazole and 4,5-dichloro-2-n-octyl-3-isothiazolinone mixture in the hollow cerium dioxide nanocontainer. The cerium dioxide nanoparticles loaded with benzotriazole and 4,5-dichloro-2-n-octyl-3-isothiazolinone were then collected by centrifugation and dried in a vacuum drying oven at 70 °C for 2 hours. h, cerium dioxide nanoparticles loaded with benzotriazole and 4,5-dichloro-2-n-octyl-3-isothiazolinone were prepared with a loading of 23.5%.

[0039] (3) Preparation of vinyltrimethoxysilane modified cerium dioxide nanoparticles (BTAH / DCOIT@CeO2 / silane): Prepare 50 mL of a 1% (v / v) vinyltrimethoxysilane / anhydrous ethanol solution, immerse 0.1 g of cerium dioxide nanoparticles loaded with the mixture in the solution for 2 hours, and then remove and dry completely at 40 °C.

[0040] (4) Pretreatment of aluminum alloy substrate: The aluminum alloy substrate is first polished with 150-grit, 320-grit, 600-grit, 1200-grit and 2000-grit sandpaper to remove impurities and oxides from the surface. Then it is ultrasonically cleaned in anhydrous ethanol and acetone for 20 minutes to remove organic matter from the surface. Finally, it is dried with N2 for later use.

[0041] (5) Preparation of composite coating: Acrylic acid, methyl methacrylate, and BTAH / DCOIT@CeO2 / silane raw materials were prepared in a mass ratio of 50:50:1. Acrylic acid and methyl methacrylate were chemically polymerized to obtain pure acrylic resin. BTAH / DCOIT@CeO2 / silane particles were then added and mixed evenly. The composite was then sprayed onto the pretreated aluminum alloy surface. After complete curing, a chemically polymerized composite coating was obtained on the aluminum alloy surface.

[0042] Example 2-2 A multi-layer self-healing anti-corrosion and anti-fouling coating and its preparation method The method for preparing this anti-corrosion and anti-fouling coating includes the following steps: Steps (1)-(4) are the same as in Example 1.

[0043] Step (5) Preparation of the composite coating: Acrylic acid, methyl methacrylate, and BTAH / DCOIT@CeO2 / silane were mixed uniformly at a mass ratio of 50:50:1, and a constant current of 0.5 mA / cm was applied. 2 Electropolymerization was performed on the aluminum alloy surface for 30 minutes. The aluminum alloy sample was then removed and dried at 40°C for 2 hours to obtain a multi-layer self-healing anti-corrosion and anti-fouling coating with a contact angle higher than 150°.

[0044] Comparative Example 2 The coating preparation method in this comparative example, referring to the method in Example 2 of prior application CN115651533A, includes the following steps: (1) Preparation of hollow cerium dioxide: Same as Example 2-1 (2) Preparation of cerium dioxide nanoparticles loaded with corrosion inhibitor (BTAH@CeO2) 1.5g of the hollow cerium dioxide nanoparticles prepared above were added to 50mL of anhydrous ethanol and sonicated (900W) for half an hour. Then, 1g of benzotriazole was added and stirred thoroughly to dissolve it completely. The sonication was continued for another half hour. After vacuuming for 20 minutes, the pressure was released to atmospheric pressure and sonicated for another half hour. This vacuuming-sonication operation was repeated 5 times to ensure that the benzotriazole corrosion inhibitor was loaded to the maximum extent in the hollow cerium dioxide nanocontainer. The hollow cerium dioxide nanoparticles loaded with benzotriazole were then collected by centrifugation and dried in a vacuum drying oven at 70℃ for 2 hours to obtain hollow cerium dioxide nanoparticles loaded with benzotriazole with a loading of 20.2%.

[0045] (3) Pretreatment of aluminum alloy substrate: Same as Example 2-1.

[0046] (4) Preparation of composite coating: Anhydrous ethanol, deionized water, hexadecyltrimethoxysilane, and ethyl silicate were mixed evenly in a volume ratio of 75:25:2:2. Acetic acid was added to adjust the pH of the solution to 4. The solution was then hydrolyzed at 40°C for 72 hours. Hollow cerium dioxide nanoparticles loaded with benzotriazole (3 g / 100 mL) were then added. After sonication (900 W) for half an hour, the solution was immersed in a pretreated aluminum alloy substrate for 20 minutes. After washing three times with anhydrous ethanol, the solution was placed in a vacuum drying oven and dried at 120°C for 1 hour to obtain the coating, which also has a contact angle higher than 150°.

[0047] Example 3: A multi-layer self-healing anti-corrosion and anti-fouling coating and its preparation method The method for preparing this anti-corrosion and anti-fouling coating includes the following steps: (1) Preparation of hollow cerium dioxide: 3 g of silica nanoparticles with a particle size of 300 nm were added to 50 mL of ethylene glycol and sonicated (900 W) for half an hour. Separately, 1.2 g of cerium nitrate hexahydrate was dissolved in 5 mL of deionized water. The two liquids were mixed and placed in a vacuum autoclave, reacting at 120 °C for 24 h. After the reaction, the autoclave was cooled to room temperature, and the product was washed five times each with deionized water and anhydrous ethanol. The product was then collected by centrifugation and washed five times each with deionized water and anhydrous ethanol. The precipitate was dried at 90 °C for 4 h. A 4 mol / L sodium hydroxide solution was used to etch a silica template, which was allowed to stand at room temperature for 2 days. The resulting solution was collected by centrifugation, washed five times each with ethanol and deionized water, and dried. Finally, the product was annealed in a muffle furnace at 500 °C for 2 h to obtain hollow cerium dioxide nanoparticles (which were confirmed to have a hollow structure by SEM and TEM).

[0048] (2) Preparation of cerium dioxide nanoparticles (BTAH / DCOIT@CeO2) loaded with a mixture: 1.2 g of the hollow cerium dioxide nanoparticles prepared above were added to a mixed solution of 25 mL anhydrous ethanol and 25 mL deionized water and sonicated (900 W) for half an hour. Then, 0.75 g of benzotriazole and 0.25 g of 4,5-dichloro-2-n-octyl-3-isothiazolinone were added, and the mixture was stirred thoroughly until completely dissolved. Sonication was continued for another half hour. After evacuating for 15 minutes, the pressure was released to atmospheric pressure, and sonication was repeated for another half hour. This vacuum-sonication cycle was repeated 5 times to ensure maximum loading of the benzotriazole and 4,5-dichloro-2-n-octyl-3-isothiazolinone mixture in the hollow cerium dioxide nanocontainer. The cerium dioxide nanoparticles loaded with benzotriazole and 4,5-dichloro-2-n-octyl-3-isothiazolinone were then collected by centrifugation and dried in a vacuum drying oven at 60 °C for 2 hours. h, cerium dioxide nanoparticles (BTAH / DCOIT@CeO2) loaded with a mixture of benzotriazole and 4,5-dichloro-2-n-octyl-3-isothiazolinone were prepared.

[0049] (3) Preparation of vinyltrimethoxysilane modified cerium dioxide nanoparticles (BTAH / DCOIT@CeO2 / silane): Prepare 50 mL of a 1% (v / v) vinyltrimethoxysilane / anhydrous ethanol solution, immerse 0.1 g of cerium dioxide nanoparticles loaded with the mixture in the solution for 2 hours, and then remove and dry completely at 40 °C.

[0050] (4) Pretreatment of copper-nickel alloy substrate: The copper-nickel alloy substrate is first polished with 150-grit, 320-grit, 600-grit, 1200-grit and 2000-grit sandpaper to remove surface impurities and oxides. Then it is ultrasonically cleaned in anhydrous ethanol and acetone for 20 minutes to remove surface organic matter. Finally, it is dried with N2 for later use.

[0051] (5) Preparation of acrylic composite coating: Acrylic acid, methyl methacrylate, and BTAH / DCOIT@CeO2 / silane were mixed evenly at a mass ratio of 50:50:3, and a constant current of 0.5 mA / cm was applied. 2 Electropolymerization was performed on the aluminum alloy surface for 30 minutes. The aluminum alloy sample was then removed and dried at 40°C for 2 hours to obtain a multi-layer self-healing anti-corrosion and anti-fouling coating with a contact angle higher than 150°.

[0052] Comparative Example 3 The coating preparation method in this comparative example, referring to the method in Example 3 of prior application CN115651533A, includes the following steps: (1) Preparation of hollow cerium dioxide: Same as Example 3 (2) Hollow cerium dioxide supported corrosion inhibitor: 1.2 g of the hollow cerium dioxide nanoparticles prepared above were added to 50 mL of anhydrous ethanol and sonicated (900 W) for half an hour. Then, 0.5 g of benzotriazole was added and stirred thoroughly until completely dissolved. Sonication continued for another half hour. Vacuum was applied for 15 min, then the pressure was released to atmospheric pressure, and sonication was repeated for another half hour. This vacuum-sonication cycle was repeated 5 times to ensure maximum loading of the benzotriazole corrosion inhibitor in the hollow cerium dioxide nanocontainer. The benzotriazole-loaded hollow cerium dioxide nanoparticles were then collected by centrifugation and dried in a vacuum drying oven at 60 °C for 2 h to obtain benzotriazole-loaded hollow cerium dioxide nanoparticles. Differential thermal analysis was performed on the hollow cerium dioxide before and after loading with benzotriazole corrosion inhibitor. The results showed that benzotriazole was loaded into the hollow cerium dioxide nanocontainer, and its loading was as high as 20.6%.

[0053] (3) Pretreatment of copper-nickel alloy substrate: The copper-nickel alloy substrate is first polished with 150-grit, 320-grit, 600-grit, 1200-grit and 2000-grit sandpaper to remove surface impurities and oxides. Then it is ultrasonically cleaned in anhydrous ethanol and acetone for 20 minutes to remove surface organic matter. Finally, it is dried with N2 for later use.

[0054] (4) Preparation of silane coating: Anhydrous ethanol, deionized water, hexadecyltrimethoxysilane, and ethyl silicate were mixed evenly in a volume ratio of 75:25:2:2, and acetic acid was added to adjust the pH of the solution to 4. The solution was then hydrolyzed at 37°C for 72 hours. Hollow cerium dioxide nanoparticles loaded with benzotriazole (2.5 g / 100 mL) were then added. After sonication (900 W) for half an hour, the solution was immersed in a pretreated copper-nickel alloy substrate for 20 minutes. After washing three times with anhydrous ethanol, the solution was placed in a vacuum drying oven and dried at 100°C for 1 hour to obtain a silane coating with both superhydrophobic and self-healing properties, and its contact angle was also higher than 150°.

[0055] Experimental Example 1: Performance Testing of Acrylic Composite Coating (1) Protective performance test The coated aluminum alloys obtained in Examples 2-1, 2-2, and Comparative Example 2 were immersed in a 3.5% NaCl solution corrosive medium for 0.5 hours, and then subjected to electrochemical impedance spectroscopy. An untreated aluminum alloy was used as a control. The results are as follows: Figure 7 As shown in Table 1.

[0056] As can be seen, compared with the untreated aluminum alloy, the composite coating prepared by the applicant using the method in the prior application CN115651533A in Comparative Example 2 showed a significant improvement in electrochemical impedance. However, further, the coating obtained by using the method in this application, with a loaded mixture and modified with vinyltrimethoxysilane, showed an even more significant improvement. Moreover, the charge transfer resistance of the composite coating prepared by the electrochemical polymerization method (Example 2-2) was significantly higher than that of the composite coating prepared by the chemical polymerization method (Example 2-1). In Example 2-2, the cerium dioxide acrylic composite coating with a loaded mixture showed the greatest increase in charge transfer resistance, even after immersion for 240 hours ( Figure 8 After that, its charge transfer resistance is much higher than that of Comparative Example 2, and the protection efficiency reaches 99.9%, which has excellent corrosion resistance and long-term protection performance.

[0057] Similarly, the protective efficiency of the hollow cerium dioxide acrylic composite coatings in the mixtures of Examples 1 and 3 was measured to be over 99.9%.

[0058] Table 1 Electrochemical impedance spectroscopy results of aluminum alloy substrates after different treatments

[0059] (2) Self-healing performance test The coatings constructed on the copper-nickel alloy surfaces in Example 3 and Comparative Example 3 were scratched with a 1 cm mark, and then immersed in a 3.5% NaCl solution as a corrosive medium. Electrochemical impedance spectroscopy was performed after immersion for 0.5 hours and 12 hours, respectively. The results are as follows: Figure 9As shown in Table 2.

[0060] As can be seen from the above test results, with the extension of soaking time (from 0.5 hours to 12 hours), the charge transfer resistance of the cerium dioxide acrylic coating with the loaded mixture in Example 3 and the coating in Comparative Example 3 both increased. However, after 12 hours of self-healing, the charge transfer resistance of the acrylic composite coating with the loaded mixture of cerium dioxide was 4 times that of the coating in Comparative Example 3, indicating that the acrylic composite coating constructed after loading the hollow cerium dioxide mixture has better self-healing performance.

[0061] Similarly, the charge transfer resistance of the cerium dioxide-acrylic composite coatings of the loaded mixtures in Examples 1 and 2 was measured to be 4.2 times and 3.9 times that of the coatings in Comparative Examples 1 and 2, respectively.

[0062] Table 2. Electrochemical impedance spectroscopy results of the sample coatings in Example 3 and Comparative Example 3.

[0063] (3) Antifouling performance test The coated aluminum alloy substrates from Examples 2-2 and Comparative Example 2 were immersed in diatom culture solution for 30 days and then observed under a fluorescence microscope. The results are as follows: Figure 10 As shown.

[0064] Fluorescence results showed that the cerium dioxide-acrylic composite coating of the loaded mixture in Examples 2-2 of the present invention had almost no diatom adhesion, while the coating surface of Comparative Example 2 had more diatom adhesion. This indicates that the multi-layer self-healing anti-corrosion and anti-fouling coating prepared by the present invention has excellent anti-fouling performance.

[0065] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for preparing a multi-layer self-healing anti-corrosion and anti-fouling coating, characterized in that, Includes the following steps: S1. Prepare hollow cerium dioxide nanoparticles; S2. Load the hollow cerium dioxide from step S1 with a mixture, the mixture being composed of a corrosion inhibitor and an antifouling agent, to obtain cerium dioxide nanoparticles loaded with the mixture. S3. Immerse the cerium dioxide nanoparticles of the loaded mixture obtained in step S2 into an organic solvent containing vinyltrimethoxysilane to prepare vinyltrimethoxysilane modified cerium dioxide nanoparticles. S4. Acrylic acid, methyl methacrylate and vinyltrimethoxysilane-modified cerium dioxide nanoparticles obtained in step S3 are mixed evenly and polymerized on the metal surface to be coated by electrochemical polymerization to form the multi-layer self-healing anti-corrosion and anti-fouling coating. Alternatively, acrylic acid, methyl methacrylate, and the vinyltrimethoxysilane-modified cerium dioxide nanoparticles obtained in step S3 can be mixed evenly and prepared by free radical solution polymerization to obtain an acrylic composite resin. The resulting composite can then be sprayed onto the metal surface to be coated to form the aforementioned multi-layer self-healing anti-corrosion and anti-fouling coating.

2. The multi-layer self-healing anti-corrosion and anti-fouling coating according to claim 1, characterized in that, The hollow cerium dioxide nanoparticles are prepared by the following method: silicon dioxide nanoparticles are dissolved in an organic solvent, and cerium nitrate hexahydrate is dissolved in water. The two solutions are combined and reacted at 120-150℃ for 20-24h. The reaction product is washed, dried, and annealed at 450-550℃ to obtain hollow cerium dioxide nanoparticles.

3. The method for preparing the multi-layer self-healing anti-corrosion and anti-fouling coating according to claim 1, characterized in that, In step S2, the corrosion inhibitor is benzotriazole and the antifouling agent is 4,5-dichloro-2-n-octyl-3-isothiazolinone.

4. The method for preparing the multi-layer self-healing anti-corrosion and anti-fouling coating according to claim 3, characterized in that, In step S2, the mass ratio of the corrosion inhibitor to the antifouling agent is 3-1:1-3.

5. The method for preparing the multi-layer self-healing anti-corrosion and anti-fouling coating according to claim 1, characterized in that, In step S2, the hollow cerium dioxide from step S1 is dissolved in a mixed solvent of anhydrous ethanol and deionized water, and then corrosion inhibitors and antifouling agents are added separately. After complete dissolution, vacuuming and ultrasonic operation are used to ensure that the corrosion inhibitors are loaded to the maximum extent in the hollow cerium dioxide. Finally, the hollow cerium dioxide nanoparticles with the loaded mixture are obtained by centrifugation and drying.

6. The method for preparing the multi-layer self-healing anti-corrosion and anti-fouling coating according to claim 5, characterized in that, In step S2, the concentration of the hollow cerium dioxide in the mixed solvent is 1-1.5 g / 50 mL, and the concentration of the mixture in the mixed solvent is 0.5-1 g / 50 mL; The vacuum-ultrasound operation involves vacuuming for 15-20 minutes, then releasing the air to atmospheric pressure, followed by ultrasound for 30-45 minutes. This operation is repeated 5-7 times.

7. The method for preparing the multi-layer self-healing anti-corrosion and anti-fouling coating according to claim 1, characterized in that, In step S3, surface modification is performed using a vinyltrimethoxysilane / anhydrous ethanol solution at a volume ratio of 0.5-2%.

8. The method for preparing the multi-layer self-healing anti-corrosion and anti-fouling coating according to any one of claims 1-7, characterized in that, In step S4, a coating is co-deposited on the surface of the metal substrate to be coated using constant current electrochemical polymerization.

9. The method for preparing the multi-layer self-healing anti-corrosion and anti-fouling coating according to claim 8, characterized in that, In step S4, the mass ratio of acrylic acid, methyl methacrylate, and vinyltrimethoxysilane-modified cerium dioxide nanoparticles is 45-55:45-55:1-3; the constant current used is 0.3-0.8 mA / cm². 2 The polymerization time is 20-40 minutes.

10. A multi-layer self-healing anti-corrosion and anti-fouling coating prepared by the preparation method according to any one of claims 1-9.

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