An ultra-bipolar coating metal composite based on a three-layer structure and a preparation method thereof

Abstract

The application belongs to the field of super-amphiphobic materials, and discloses a super-amphiphobic coated metal composite material based on a three-layer structure, which comprises, from bottom to top, a silanized metal substrate, an intermediate layer and a super-amphiphobic coating layer; the intermediate layer is formed by immersing and drying an emulsion of microcapsules dissolved in an organic polymer matrix solution, and the microcapsules are formed by wrapping photosensitizers and first SiO2 super-amphiphobic particles with a polymer matrix; the super-amphiphobic coating layer contains second SiO2 super-amphiphobic particles; the first SiO2 super-amphiphobic particles and the second SiO2 super-amphiphobic particles are nano-SiO2 modified by silane coupling agents and then modified by perfluoroalkyl silane. By introducing nano-SiO2 with low surface energy functional groups into the intermediate layer and the super-amphiphobic coating layer, and by designing the intermediate layer to be formed by drying microcapsules containing SiO2 super-amphiphobic particles dissolved in an organic polymer matrix solution, the surface of the composite material and the composite material after surface damage can still maintain the effects of being hydrophobic and oleophobic.

Description

Technical Field

[0001] This invention belongs to the technical field of superhydrophobic materials, and more specifically, relates to a superhydrophobic coated metal composite material based on a three-layer structure and its preparation method. Background Technology

[0002] Metallic materials play an irreplaceable and crucial role in the development of various industries and fields today, possessing superior performance. However, in practical applications, corrosion is an unavoidable problem for metallic materials, significantly affecting their mechanical properties and service life. Water is the most common corrosive medium, especially affecting carbon steel. Preventing water from contacting metal surfaces reduces the risk of water-induced surface contamination. Similarly, avoiding direct contact between oil and metal improves the anti-fouling properties of metal products and their drag-reducing ability in oil. These measures all contribute to maintaining the stability of metallic materials.

[0003] Superhydrophobic and superoleophobic coatings, with their dual properties of superhydrophobicity and superoleophobicity, have shown broad application prospects, including metal corrosion protection, self-cleaning, antifouling, anti-icing, drag reduction, and liquid separation. Therefore, successfully preparing such high-performance superhydrophobic coatings on metal substrates will enhance the protection of metal materials and extend the service life of metal products. In recent years, with the deepening research on superhydrophobic coatings, preparation methods have become increasingly diverse. Regardless of the method used, the basic principle remains the same: first, a micro-nano rough structure is constructed on the substrate surface, and then modified with low surface energy materials to impart superhydrophobic and superoleophobic properties, such as template methods, etching methods, and electrodeposition methods. However, these methods all suffer from poor wear resistance and weather resistance, and short service life. Currently, research on superhydrophobic coatings is mainly at the laboratory basic research stage, facing challenges such as complex processes, high preparation costs, low reproducibility, and insufficient stability and mechanical strength, making it difficult to realize large-scale applications. Summary of the Invention

[0004] To address the above-mentioned deficiencies or improvement needs of existing technologies, this invention provides a superhydrophobic coating metal composite material based on a three-layer structure and its preparation method. The purpose is to improve the superhydrophobic properties of the metal composite material and solve the problem of insufficient weather resistance of the metal composite material by introducing nano-SiO2 modified with low surface energy functional groups into the intermediate layer and the superhydrophobic coating, and designing the intermediate layer as a microcapsule containing SiO2 superhydrophobic particles dissolved in an organic polymer matrix solution and dried.

[0005] To achieve the above objectives, according to one aspect of the present invention, a superhydrophobic coating metal composite material based on a three-layer structure is provided, comprising, from bottom to top: a silanized metal matrix, an intermediate layer, and a superhydrophobic coating;

[0006] The intermediate layer is formed by dipping and drying an emulsion of microcapsules dissolved in an organic polymer matrix solution, and the microcapsules are formed by encapsulating photosensitizers and first SiO2 superhydrophobic particles in a polymer matrix.

[0007] The superhydrophobic coating contains second SiO2 superhydrophobic particles;

[0008] The first SiO2 superhydrophobic particles and the second SiO2 superhydrophobic particles are prepared by modifying nano-SiO2 with silane coupling agent with perfluoroalkyl silane.

[0009] As a preferred embodiment of the present invention, the organic polymer matrix is ​​selected from polydimethylsiloxane, epoxy silane resin, epoxy modified silicone resin or γ-glycidoxypropyltrimethoxysilane.

[0010] As a preferred embodiment of the present invention, the polymer matrix is ​​selected from polystyrene, polyurethane or polyimide;

[0011] The photosensitizer is selected from benzophenone, stilbene diketone, or benzotriazole;

[0012] The mass ratio of the photosensitizer to the first SiO2 superhydrophobic particles is (0.5-2):1;

[0013] The mass ratio of either the photosensitizer or the first SiO2 superhydrophobic particles to the polymer matrix is ​​less than 1:10.

[0014] As a preferred embodiment of the present invention, the superhydrophobic coating further includes an epoxy resin, wherein the epoxy resin is selected from epoxy resin E44 or epoxy resin E51;

[0015] The mass ratio of the epoxy resin to the second SiO2 superhydrophobic particles is (1-3):1.

[0016] As a preferred embodiment of the present invention, the silane coupling agent modified nano-SiO2 is prepared by hydrolyzing the silane coupling agent to form a silane coupling agent hydrolysate, and then mixing it with nano-SiO2 particles.

[0017] The perfluoroalkyl silane is selected from one of perfluorodecyltrimethoxysilane, perfluorooctyltriethoxysilane, perfluorooctyltriethoxysilane, perfluorobutylvinyltriethoxysilane, perfluorohexylpropyltrichlorosilane, and perfluorohexyltrimethoxysilane; perfluorodecyltrimethoxysilane is preferred.

[0018] As a preferred embodiment of the present invention, the nano-SiO2 modified by the silane coupling agent is prepared by adding silane coupling agent KH-570 to a mixed solution of butyl acetate and deionized water, and then adding polypropylene and tetrafluoroethylene resin in sequence and mixing thoroughly to obtain a hydrolysate of silane coupling agent KH-570, and then adding nano-SiO2 particles to a mixed solution of anhydrous ethanol and ammonia.

[0019] As a preferred embodiment of the present invention, the modification of the nano-SiO2 modified with silane coupling agent by perfluorodecyltrimethoxysilane is specifically achieved by adding the nano-SiO2 modified with silane coupling agent and perfluorodecyltrimethoxysilane to a hexane solution with a pH of 5.5-7.5.

[0020] As a preferred embodiment of the present invention, the metal matrix is ​​selected from one of iron, aluminum, copper, magnesium, or an iron alloy.

[0021] As a preferred embodiment of the present invention, the thickness of the intermediate layer is 0.5 to 1.5 μm; and the thickness of the superhydrophobic coating is 2 to 3 μm.

[0022] According to another aspect of the present invention, a method for preparing a superhydrophobic coated metal composite material based on a three-layer structure as described in any of the first aspects of the present invention is provided, comprising the following steps:

[0023] Includes the following steps:

[0024] (1) The silanized metal matrix is ​​immersed in the intermediate layer solution and dried and cured to obtain a metal matrix with an intermediate layer;

[0025] The intermediate layer solution is prepared by adding a photosensitizer and second SiO2 superhydrophobic particles to a polymer matrix solution and mixing them evenly, then adding a precipitant, mixing thoroughly at room temperature, co-precipitating thoroughly, drying to obtain microcapsules, and dissolving the microcapsules in an organic polymer matrix solution to obtain the intermediate layer solution.

[0026] (2) The suspension containing the second SiO2 superhydrophobic particles is mixed with epoxy resin and sprayed onto the surface of the intermediate layer of the metal matrix with the intermediate layer by spraying method. After heating and curing, the superhydrophobic coated metal composite material is obtained; wherein, the preparation of the first SiO2 superhydrophobic particles and the second SiO2 superhydrophobic particles is as follows: nano SiO2 is modified by silane coupling agent hydrolysate to prepare silane coupling agent modified nano SiO2, and the silane coupling agent modified nano SiO2 is modified by perfluoroalkyl silane.

[0027] In summary, compared with the prior art, the technical solutions conceived in this invention have the following beneficial effects:

[0028] (1) The present invention proposes a superhydrophobic coating metal composite material based on a three-layer structure, which includes a silanized metal matrix, an intermediate layer and a superhydrophobic coating from bottom to top, and each of the superhydrophobic coating and the intermediate layer independently contains SiO2 superhydrophobic particles.

[0029] First, the SiO2 superhydrophobic particles replace the original high surface energy groups on the surface of nano-SiO2 with low surface energy functional groups. The modified SiO2 particles have a large number of low surface energy functional groups on their surface. At the same time, due to the formation of a dual rough structure at the micron and nano scale on the surface of nano-SiO2, the superhydrophobic surface is constructed together with the low surface energy modification. Furthermore, the nano-SiO2 surface has abundant silanol groups (Si-OH), which facilitates chemical modification and can improve mechanical strength and wear resistance, and has good chemical stability.

[0030] Furthermore, SiO2 superhydrophobic particles are introduced into the coating and intermediate layer of the metal composite material, so that the surface of the metal composite material maintains hydrophobic and oleophobic effects. At the same time, an intermediate layer with a microcapsule structure is prepared by encapsulating SiO2 superhydrophobic particles and photosensitizer with a polymer matrix. When the coating surface is damaged, the intermediate layer at the damaged area is exposed. Under light irradiation, the photosensitizer absorbs light energy to destroy the microcapsules and release the SiO2 superhydrophobic particles stored inside the microcapsules. This allows the damaged area to continue to maintain the superhydrophobic properties and significantly improves the weather resistance of the superhydrophobic coating.

[0031] (2) Preferably, based on the fact that the metal matrix needs to be alkylated, the intermediate layer contains, for example, alkyl groups in polydimethylsiloxane, and the intermediate layer contains, for example, alkyl groups in polydimethylsiloxane, and the epoxy resin in the superhydrophobic coating changes from the original inorganic-organic combination to an organic-organic combination, which significantly improves the bonding strength and effectively enhances the bonding effect between the coating surface and the substrate material.

[0032] (3) Preferably, the mass ratio of the polymer matrix to the first SiO2 superhydrophobic particles should be greater than 10:1, so as to achieve the effect of microcapsules fully encapsulating the first SiO2 superhydrophobic particles.

[0033] (4) Preferably, the mass ratio of epoxy resin to the second SiO2 superhydrophobic particles should be between 1:3 and 1:1. Too much epoxy resin will lead to a decrease in hydrophobic and oleophobic properties, while too little epoxy resin will lead to a decrease in bonding strength.

[0034] (5) Preferably, the thickness of the intermediate layer should be controlled within the range of 0.5 to 1.5 μm, and the thickness of the super hydrophobic coating should be controlled within the range of 1.5 to 2.5 μm. If the coating thickness is too thin, the coating will fail after slight wear and the hydrophobic and oleophobic properties will decrease. If the coating thickness is too thick, it will lead to unnecessary cost increases.

[0035] (6) This invention prepares a microcapsule structure by encapsulating second SiO2 superhydrophobic particles and a photosensitizer in a polymer matrix, and then dissolving the microcapsule in an organic polymer matrix solution to form an intermediate layer solution. An alkylated metal matrix is ​​then immersed in the intermediate layer solution, dried, and cured to obtain a metal matrix with an intermediate layer. A superhydrophobic coating, a mixture of second SiO2 superhydrophobic particles and epoxy resin, is then sprayed onto the metal matrix using a spraying method. After curing, a superhydrophobic coating metal composite material is formed. This process is relatively simple, less affected by experimental conditions, uses low-cost raw materials, and innovatively proposes a three-layer strong bonding structure.

[0036] In summary, this invention innovatively proposes the design of a three-layer strongly bonded metal composite material. This material is prepared by secondary modification of nano-SiO2 with silane coupling agent and perfluorosilicone-based trimethoxysilane, using a microcapsule structure of second SiO2 superhydrophobic particles as the intermediate layer. The intermediate layer solution is sequentially immersed on the surface of an alkylated metal matrix, and then a superhydrophobic coating made by mixing the first SiO2 superhydrophobic particles with epoxy resin is sprayed onto the surface. This process effectively improves the weather resistance of the superhydrophobic coating, which helps to provide a new idea and method for the research and application of metal-based superhydrophobic coatings. Attached Figure Description

[0037] Figure 1 This is a flowchart illustrating the preparation process of the superhydrophobic coated metal composite material based on a three-layer structure, as exemplified in Examples 1-5 of this invention.

[0038] Figure 2 This is a flowchart illustrating the preparation process of SiO2 superhydrophobic particles as exemplified in Examples 1-5 of this invention;

[0039] Figure 3 This is a flowchart illustrating the preparation of the intermediate layer solution in Examples 1-5 of the present invention;

[0040] Figure 4 This is a flowchart illustrating the process of obtaining a superhydrophobic coating by spraying a second SiO2 superhydrophobic particle solution, as exemplified in Examples 1-5 of the present invention.

[0041] Figure 5 This is an example of the oil contact angle test of a superhydrophobic coated metal composite material with a three-layer structure before and after the wear resistance test, as exemplified in Embodiment 1 of the present invention. Figure 1 In the figure, (a) is the oil contact angle before the wear resistance test, and (b) is the oil contact angle after the wear resistance test;

[0042] Figure 6 This is an example of Embodiment 2 of the present invention, showing the oil contact angle test of a superhydrophobic coated metal composite material with a three-layer structure before and after a wear resistance test. Figure 2In the figure, (a) is the oil contact angle before the wear resistance test, and (b) is the oil contact angle after the wear resistance test;

[0043] Figure 7 This is an example of the oil contact angle test of the superhydrophobic coated metal composite material based on a three-layer structure before and after the wear resistance test in Embodiment 3 of the present invention. Figure 3 In the figure, (a) is the oil contact angle before the wear resistance test, and (b) is the oil contact angle after the wear resistance test;

[0044] Figure 8 This is an example of the oil contact angle test of the superhydrophobic coated metal composite material based on a three-layer structure before and after the wear resistance test in Embodiment 4 of the present invention. Figure 4 In the figure, (a) is the oil contact angle before the wear resistance test, and (b) is the oil contact angle after the wear resistance test;

[0045] Figure 9 This is an example of the oil contact angle test of the superhydrophobic coated metal composite material based on a three-layer structure before and after the wear resistance test in Embodiment 5 of the present invention. Figure 5 In the figure, (a) is the oil contact angle before the wear resistance test, and (b) is the oil contact angle after the wear resistance test. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0047] This invention employs a co-precipitation method to prepare an intermediate layer solution. An alkylated metal substrate is immersed in an intermediate layer solution containing first SiO2 superhydrophobic particles. After drying and curing, a metal substrate with an intermediate layer is obtained. A spraying method is used to prepare a metal-based superhydrophobic coating. Specifically, a prepared suspension of second SiO2 superhydrophobic particles is mixed with epoxy resin and uniformly sprayed onto the intermediate layer on the surface of the metal substrate using a spray gun. After heating and curing, a metal-based superhydrophobic coating is obtained.

[0048] The SiO2 superhydrophobic particles are prepared by modifying nano-SiO2 with silane coupling agent with perfluoroalkyl silane. Since there are selectable types of silane coupling agent and perfluoroalkyl silane, the first SiO2 superhydrophobic particles in the intermediate layer and the second SiO2 superhydrophobic particles in the superhydrophobic coating are the same or different SiO2 superhydrophobic particles.

[0049] The secondary modified SiO2 and SiO2 superhydrophobic particles mentioned in the instruction manual are the same substance.

[0050] The specific preparation scheme of the superhydrophobic coated metal composite material based on the three-layer structure of the present invention is as follows:

[0051] (1) Alkylation treatment of metal matrix:

[0052] The metal substrate is mechanically polished with sandpaper, and then cleaned and purified with anhydrous ethanol and deionized water to remove the oxide layer and impurities from the surface. It is then dried before use. Specifically, iron, aluminum, and copper are preferred metal substrate materials.

[0053] A silane coupling agent, such as one of silane coupling agents KH-570, KH-560 and KH-550, is dissolved in deionized water and anhydrous ethanol and hydrolyzed under a neutral environment to obtain a silane coupling agent hydrolysate.

[0054] The metal substrate, after removing the oxide layer and impurities, is immersed in a silane coupling agent hydrolysate and dried at 70–90°C for 1–2 hours to complete the curing of the silane film. Notably, the coating only needs to be in a semi-cured state during preparation; complete drying and curing are not required.

[0055] (2) Preparation of SiO2 superhydrophobic particles or modification of silica:

[0056] A suitable amount of silane coupling agent was added to a mixed solution of butyl acetate and deionized water, followed by the sequential addition of a certain amount of polypropylene and tetrafluoroethylene resin. The mixture was stirred at room temperature until fully stirred to obtain a hydrolysate of the coupling agent. A suitable amount of nano-SiO2 particles was taken, and appropriate amounts of anhydrous ethanol and ammonia were added. After magnetic stirring until homogeneous, a uniformly dispersed nano-SiO2 suspension was obtained. The obtained hydrolysate of the coupling agent was then added to the nano-SiO2 suspension, and the mixture was stirred at a constant temperature of 70–85°C for 4–5 hours using a magnetic stirrer to obtain a mixed solution. This mixed solution was filtered several times, and the filter cake was washed multiple times with ethyl acetate. Finally, it was dried in a drying oven to obtain nano-SiO2 particles modified with the silane coupling agent.

[0057] Take an appropriate amount of nano-SiO2 particles modified with a silane coupling agent, add them to a mixture of n-hexane solution and HCl with a concentration between 0.65M and 0.55M-0.70M, and maintain a constant temperature of 65℃ with magnetic stirring for 1.5 hours. Slowly add a certain amount of perfluoroalkylsilane, such as perfluorodecyltrimethoxysilane, perfluorooctyltriethoxysilane, perfluorooctyltriethoxysilane, perfluorobutylvinyltriethoxysilane, perfluorohexylpropyltrichlorosilane, and perfluorohexyltrimethoxysilane. Continue to maintain a constant temperature of 65℃ (60-70℃) with magnetic stirring for 5.0-6.0 hours to obtain a nano-SiO2 solution that has been modified with perfluoroalkylsilane for the second time. Finally, filter the solution 3 to 5 times in a sand core funnel, and dry it in a drying oven at 80℃ for 3-4 hours to obtain SiO2 superhydrophobic particles.

[0058] The mass ratio of silane coupling agent to SiO2 is controlled between 1:15 and 1:25, and the amount of perfluoroalkylsilane used is sufficient.

[0059] (3) Preparation of a metal substrate containing an intermediate layer:

[0060] A polymer matrix, such as one of polystyrene, polyurethane and polyimide, deionized water and toluene are mixed in a neutral environment and stirred with a magnetic stirrer at 40-50°C for 2-3 hours to obtain a polymer matrix solution.

[0061] A certain amount of photosensitizer, such as benzophenone, stilbene diketone, benzotriazole, or a benzotriazole derivative, is added sequentially to an appropriate amount of polymer matrix solution. This mixture is then magnetically stirred at a constant temperature of 30–40°C for 1–2 hours with the aforementioned SiO2 superhydrophobic particles to obtain a homogeneous mixed solution. A precipitant, polyethylene glycol (15–25% polystyrene), is slowly added to the mixed solution while stirring thoroughly at room temperature to ensure complete co-precipitation. The solution is then placed in a drying oven and dried at 80°C for 3–4 hours to obtain microcapsules containing both photosensitizer and SiO2 superhydrophobic particles.

[0062] The microcapsules containing photosensitizers and SiO2 superhydrophobic particles were added to a certain amount of organic polymer matrix solution. For example, the organic polymer matrix was selected from polydimethylsiloxane (PDMS), epoxy silane resin (including bisphenol A type epoxy resin or phenolic epoxy resin), epoxy modified silicone resin or γ-glycidoxypropyltrimethoxysilane (GPTMS). After mixing evenly, the alkylated metal substrate sample was immersed in the mixed solution. After immersion, the sample was dried in a drying oven at 80°C for 1.5 hours to complete the curing of the intermediate layer.

[0063] (4) Preparation of superhydrophobic coated metal composite materials:

[0064] A certain amount of epoxy resin, such as epoxy resin E44 or epoxy resin E51, is diluted with ethyl acetate and mixed with the above-mentioned SiO2 superhydrophobic particles. The mixture is stirred at a constant temperature of 25-30°C for 2-3 hours. Then, W593 modified amine curing agent is slowly added and stirring is continued for 1-2 hours (the mass ratio of curing agent to epoxy resin is selected as 30-40%) to form a superhydrophobic suspension.

[0065] Finally, the obtained superhydrophobic suspension is evenly sprayed onto the surface of the intermediate layer of the metal substrate containing the intermediate layer using a spray gun. The temperature of the drying oven is controlled at 70-80℃, and the superhydrophobic coated metal composite material is obtained after constant temperature curing for 2-3 hours.

[0066] The present invention uses a spray gun with a nozzle diameter of 0.7mm, an exhaust pressure of 0.28MPa, controls the distance between the spray gun and the metal substrate surface to be 20-25cm, and the spray gun moving speed to be about 5cm / s.

[0067] The three-layer strongly bonded superhydrophobic coated metal composite material prepared based on the above embodiments consists of a silanized metal matrix, an intermediate layer, and a superhydrophobic coating layer, from bottom to top. The superhydrophobic coating layer and the intermediate layer each contain SiO2 superhydrophobic particles independently.

[0068] The intermediate layer is formed by dissolving a polymer matrix and microcapsules containing photosensitizers and SiO2 superhydrophobic particles in an organic polymer matrix solution. The intermediate layer exhibits high bonding strength with both the primer (metal substrate surface) and the topcoat (superhydrophobic coating), effectively enhancing the adhesion between the coating surface and the substrate material. Simultaneously, when the topcoat (superhydrophobic coating) surface is damaged, the intermediate layer is exposed at the damaged area. Under light irradiation, the photosensitizer absorbs light energy, destroying the microcapsules and releasing the stored SiO2 superhydrophobic particles. This allows the damaged area to maintain its superhydrophobic properties, significantly improving the weather resistance of the superhydrophobic coating.

[0069] Some specific embodiments will be given below, along with detailed descriptions in conjunction with the accompanying drawings.

[0070] The specific preparation methods of Examples 1-5 are as follows: Figure 1 As shown, the details are as follows:

[0071] (1) Silanization treatment of metal matrix:

[0072] The metal substrate is mechanically polished using sandpaper of different grits ranging from 100 to 2000 grit, followed by ultrasonic cleaning in anhydrous ethanol for 20 minutes. After removal, it is rinsed with deionized water 3-5 times to thoroughly remove all impurities and residual solvent from the surface. The substrate is then dried with cool air and stored in a dry, clean environment for later use.

[0073] The silane coupling agent KH-570, deionized water and anhydrous ethanol were mixed in a neutral environment at a mass ratio of 1:2:4 and stirred with a magnetic stirrer at 30°C for 1.5 h to obtain a hydrolyzed silane coupling agent KH-570 solution.

[0074] The metal substrate sample after removing the oxide layer and impurities was immersed in a silane coupling agent KH-570 solution for 180 seconds. After immersion, the sample was dried in a drying oven at 80°C for 1.5 hours to complete the curing of the silane film.

[0075] (2) Preparation of SiO2 superhydrophobic particles, such as Figure 2 As shown:

[0076] Take 0.3g of silane coupling agent KH-570 and add it to a mixed solution of butyl acetate and deionized water. Then add 5.0g of polypropylene and tetrafluoroethylene resin in sequence. Stir the mixture magnetically at 25℃ for 5h to obtain the hydrolysate of coupling agent KH-570.

[0077] Take 5.0 g of nano-SiO2 particles, add 150 ml of anhydrous ethanol and 20 mL of ammonia water, and stir magnetically for 1.5 h to obtain a uniformly dispersed nano-SiO2 suspension. Then, add the obtained coupling agent KH-570 hydrolysate to the suspension and stir at a constant temperature of 80 °C for 4.5 h in a magnetic stirrer. Filter the above mixture 3 to 5 times, wash the filter cake several times with ethyl acetate, and then dry it in a drying oven at 80 °C for later use.

[0078] Take 1.2g of nano-SiO2 modified with silane coupling agent KH-570, add it to a mixture of n-hexane solution and 0.65M HCl, keep the temperature constant at 65℃ and stir magnetically for 1.5h, slowly add a certain amount of perfluorodecyltrimethoxysilane solution, and continue to keep the temperature constant at 65℃ and stir magnetically for 5h to obtain SiO2 superhydrophobic particle solution. Finally, filter it 3-5 times in a sand core funnel, put it in a drying oven and dry it at 80℃ for 3h to obtain SiO2 superhydrophobic particles.

[0079] (3) Preparation of a metal substrate containing an intermediate layer:

[0080] like Figure 3As shown, polystyrene, deionized water, and toluene were mixed in a 1:2:5 mass ratio under neutral conditions and stirred with a magnetic stirrer at 40°C for 2 hours to obtain a polystyrene solution. 1.0 g of benzophenone and the aforementioned SiO2 superhydrophobic particles were added sequentially to 50 mL of the polystyrene solution, and the mixture was stirred magnetically at 30°C for 1 hour to obtain a homogeneous solution. Polyethylene glycol (20% polystyrene) was slowly added to the solution while stirring at a constant temperature of 25°C to ensure thorough mixing of the polystyrene, benzophenone, and SiO2 superhydrophobic particles, allowing for complete co-precipitation. The mixture was then dried in an oven at 80°C for 3.5 hours to obtain microcapsules containing a photosensitizer and SiO2 superhydrophobic particles. The obtained microcapsules were added to 500 mL of PDMS and stirred at a constant temperature of 30°C for 2 hours to form a mixed solution.

[0081] The treated metal substrate sample was immersed in the mixed solution for 240 seconds. After immersion, the sample was dried in a drying oven at 80°C for 1.5 hours to complete the curing of the intermediate layer.

[0082] (4) Preparation of superhydrophobic coated metal composite materials:

[0083] like Figure 4 As shown, a certain amount of epoxy resin E44 was diluted with ethyl acetate and mixed with the obtained SiO2 superhydrophobic particles. The mixture was stirred at a constant temperature of 30°C for 2.0 h. Then, W593 modified amine curing agent was slowly added and stirring continued for 1.5 h. The mass ratio of curing agent to epoxy resin E44 was selected as 35%. Finally, the obtained superhydrophobic suspension was uniformly sprayed onto the surface of the intermediate layer of the metal substrate containing the intermediate layer using a spray gun. The temperature of the drying oven was controlled at 80°C, and the mixture was cured at a constant temperature for 2.5 h to obtain the superhydrophobic coated metal composite material.

[0084] The spray gun used has a nozzle diameter of 0.7mm, an exhaust pressure of 0.28MPa, and the distance between the spray gun and the metal substrate surface is controlled at 20-25cm. The spray gun moving speed is about 5cm / s.

[0085] Based on the specific preparation method described above, examples were prepared with different mass ratios of SiO2 superhydrophobic particles and epoxy resin E44; the thickness of each layer was uncontrollable, but the same preparation steps were maintained within a reasonable range. Details are as follows:

[0086] In Example 1, the intermediate layer is 1.28 μm thick, the superhydrophobic coating is 2.86 μm thick, and the corresponding mass ratio of the second SiO2 superhydrophobic particles to epoxy resin E44 is 1:8.

[0087] In Example 2, the intermediate layer is 1.24 μm thick, the superhydrophobic coating is 2.75 μm thick, and the corresponding mass ratio of the second SiO2 superhydrophobic particles to epoxy resin E44 is 1:5.

[0088] In Example 3, the intermediate layer is 1.31 μm thick, the superhydrophobic coating is 2.64 μm thick, and the corresponding mass ratio of the second SiO2 superhydrophobic particles 2 to epoxy resin E44 is 1:3.

[0089] In Example 4, the intermediate layer thickness was 1.22 μm, the superhydrophobic layer thickness was 2.51 μm, and the corresponding mass ratio of the second SiO2 superhydrophobic particles to epoxy resin E44 was 1:1.5.

[0090] In Example 5, the intermediate layer thickness is 1.34 μm, the superhydrophobic coating thickness is 2.49 μm, and the corresponding mass ratio of the second SiO2 superhydrophobic particles to epoxy resin E44 is 1:1.

[0091] The superhydrophobic coated metal composite material prepared in the above embodiments was subjected to water and oil contact angle tests, as well as wear resistance tests, based on the superhydrophobic coating:

[0092] Adhesion performance test:

[0093] The adhesion of the superhydrophobic coating prepared in this invention was tested using a cross-cut adhesion test. The coating system was cut into a grid pattern while ensuring the scratches penetrated the substrate to evaluate the separation resistance between the coating and the substrate. A 2mm cross-cut adhesion test blade was used to cut the coating surface at a speed of approximately 30mm / s. The coating was then rotated 90° and the above operation was repeated to draw a 2×2mm grid pattern on the sample surface, ensuring the scratch depth penetrated the coating. After gently brushing away debris from the coating surface with a soft brush, transparent cross-cut adhesion tape was used. The tape was repeatedly pressed with the fingers to maintain good contact with the coating surface, and then slowly peeled off at an angle of approximately 60°. After peeling, the peeling condition of the sample surface was observed, and the coating was graded according to the adhesion rating standard.

[0094] Abrasion resistance test:

[0095] This invention uses the sand impact test, which is more likely to occur under natural conditions, to quantify the wear resistance of the prepared superhydrophobic coating surface. First, the prepared sample is fixed on an inclined plane at a 30° angle. 50g of fine sand for one sand impact is weighed using an electronic balance. The sand outlet of the separatory funnel is vertically aligned with the center of the sample. The sample surface is continuously impacted with fine sand with a diameter of about 200μm at a height of 30cm. After 10 cycles of this test, the change in the contact angle of the superhydrophobic coating is measured.

[0096] In Example 1, the water contact angle and oil contact angle were 135.9° and 110.3°, respectively. According to the cross-cut adhesion test in GB / T8266-88, the superhydrophobic coating had an adhesion rating of 5B. The change in oil contact angle before and after wear was also observed after the aforementioned abrasion resistance test. Figure 5 In the figure, (a) is the oil contact angle before the wear resistance test (110.3°), and (b) is the oil contact angle after the wear resistance test (106.5°).

[0097] In Example 2, the water contact angle and oil contact angle were 149.1° and 138.7°, respectively. According to the cross-cut adhesion test in GB / T8266-88, the superhydrophobic coating had an adhesion rating of 5B. The change in oil contact angle before and after wear was also observed after the aforementioned abrasion resistance test. Figure 6 In the figure, (a) is the oil contact angle before the wear resistance test (138.7°), and (b) is the oil contact angle after the wear resistance test (130.4°).

[0098] In Example 3, the water contact angle and oil contact angle were 156.9° and 151.1°, respectively; according to the cross-cut adhesion test in GB / T8266-88, the adhesion grade of the superhydrophobic coating was 4B. Figure 7 In the figure, (a) is the oil contact angle before the wear resistance test (151.1°), and (b) is the oil contact angle after the wear resistance test (142.4°).

[0099] In Example 4, the water contact angle and oil contact angle were 165.1° and 157.9°, respectively; according to the cross-cut adhesion test in GB / T8266-88, the adhesion grade of the superhydrophobic coating was 4B. Figure 8 In the figure, (a) is the oil contact angle before the wear resistance test (157.9°), and (b) is the oil contact angle after the wear resistance test (150.2°).

[0100] In Example 5, the water contact angle and oil contact angle were 164.5° and 157.3°, respectively; according to the cross-cut adhesion test in GB / T8266-88, the adhesion grade of the superhydrophobic coating was 3B. Figure 9 In the figure, (a) is the oil contact angle before the wear resistance test (157.3°), and (b) is the oil contact angle after the wear resistance test (149.7°).

[0101] Based on the above tests of water and oil contact angles, as well as the wear resistance test, it can be concluded that:

[0102] The mass ratio of the second SiO2 superhydrophobic particles to epoxy resin E44 is controlled between 1:3 and 1:1. Excessive epoxy resin content results in a lower coating surface roughness, fewer low surface energy nanoparticles, and lower hydrophobicity and oleophobicity; insufficient epoxy resin content reduces the adhesion of the modified nanoparticles, leading to decreased coating wear resistance and adhesion. According to national standards, if a small portion of the coating peels off at scratches, and this peeling is less than 5% of the total coating area, the coating adhesion grade reaches 4B, which meets the requirements. Therefore, the corresponding metal composite materials in Examples 3-5 achieve the required coating adhesion grades.

[0103] There is no unified standard for wear resistance. The coating prepared in this invention exhibits an oleophobic angle change of approximately 5% before and after wear, and retains its superhydrophobic and amphoteric properties even after wear, indicating excellent wear resistance. When the outermost superhydrophobic and amphoteric coating is damaged due to excessive wear, the intermediate layer is exposed at the damaged area. The photosensitizer in the intermediate layer absorbs energy under light, causing the microcapsules to rupture and releasing the SiO2 superhydrophobic and amphoteric particles stored inside, thus allowing the damaged area to continue to maintain its superhydrophobic and amphoteric properties.

[0104] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A superhydrophobic coated metal composite material based on a three-layer structure, characterized in that, From bottom to top, it includes: a silanized metal substrate, an intermediate layer, and a superhydrophobic coating; The intermediate layer is formed by dipping and drying an emulsion of microcapsules dissolved in an organic polymer matrix solution, and the microcapsules are formed by encapsulating photosensitizers and first SiO2 superhydrophobic particles in a polymer matrix. The superhydrophobic coating contains second SiO2 superhydrophobic particles; the thickness of the intermediate layer is 0.5–1.5 μm; The first SiO2 superhydrophobic particles and the second SiO2 superhydrophobic particles are prepared by modifying nano-SiO2 with silane coupling agent with perfluoroalkyl silane. The organic polymer matrix is ​​selected from polydimethylsiloxane; the polymer matrix is ​​selected from polystyrene; the photosensitizer is selected from benzophenone, stilbene diketone, or benzotriazole; the mass ratio of the photosensitizer to the first SiO2 superhydrophobic particles is (0.5-2):1; the mass ratio of either the photosensitizer or the first SiO2 superhydrophobic particles to the polymer matrix is ​​less than 1:10; The superhydrophobic coating further includes an epoxy resin, which is selected from epoxy resin E44 or epoxy resin E51; the mass ratio of the epoxy resin to the second SiO2 superhydrophobic particles is (1-3):1; the perfluoroalkylsilane is selected from perfluorodecyltrimethoxysilane.

2. The superhydrophobic coated metal composite material based on a three-layer structure as described in claim 1, characterized in that, The silane coupling agent modified nano-SiO2 is prepared by hydrolyzing the silane coupling agent to form a silane coupling agent hydrolysate, and then mixing it with nano-SiO2 particles.

3. The superhydrophobic coated metal composite material based on a three-layer structure as described in claim 2, characterized in that, The silane coupling agent modified nano-SiO2 is prepared by adding silane coupling agent KH-570 to a mixed solution of butyl acetate and deionized water, followed by the sequential addition of polypropylene and tetrafluoroethylene resin and thorough mixing to obtain a hydrolysate of silane coupling agent KH-570, and then adding nano-SiO2 particles to a mixed solution of anhydrous ethanol and ammonia.

4. The superhydrophobic coated metal composite material based on a three-layer structure as described in claim 1, characterized in that, The modification of nano-SiO2 modified with silane coupling agent by perfluorodecyltrimethoxysilane is specifically achieved by adding the nano-SiO2 modified with silane coupling agent and perfluorodecyltrimethoxysilane to a hexane solution with a pH of 5.5-7.

5.

5. The superhydrophobic coated metal composite material based on a three-layer structure as described in claim 1, characterized in that, The metal matrix is ​​selected from one of iron, aluminum, copper, magnesium, or an iron alloy.

6. The superhydrophobic coated metal composite material based on a three-layer structure as described in claim 1, characterized in that, The thickness of the superhydrophobic coating is 2–3 μm.

7. The method for preparing a superhydrophobic coated metal composite material based on a three-layer structure as described in any one of claims 1 to 6, characterized in that, Includes the following steps: (1) The silanized metal matrix is ​​immersed in an intermediate layer solution and dried and cured to obtain a metal matrix with an intermediate layer; wherein, the intermediate layer solution is prepared by adding a photosensitizer and first SiO2 superhydrophobic particles to a polymer matrix solution and mixing them evenly, then adding a precipitant, mixing thoroughly at room temperature, co-precipitating thoroughly, drying to obtain microcapsules, and dissolving the microcapsules in an organic polymer matrix solution to obtain the intermediate layer solution; (2) A suspension containing second SiO2 superhydrophobic particles is mixed with epoxy resin and sprayed onto the surface of the intermediate layer of the metal matrix with the intermediate layer by spraying method. After heating and curing, a superhydrophobic coated metal composite material is obtained; wherein, the preparation of the first SiO2 superhydrophobic particles and the second SiO2 superhydrophobic particles is as follows: nano SiO2 is modified by silane coupling agent hydrolysate to prepare silane coupling agent modified nano SiO2, and the silane coupling agent modified nano SiO2 is obtained by perfluoroalkyl silane modification.

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