A superhydrophobic and superoleophobic coating with a columnar structure, its preparation method and application

Abstract

The present invention relates to a superhydrophobic and superoleophobic coating with a columnar structure, its preparation method and application, including a substrate. An array composed of a number of columnar structures is prepared on the surface of the substrate by laser engraving. A reentrant structure is generated by growing nano-ZnO needle-like structures on the surface of the columnar structures by hydrothermal synthesis method to construct a multi-level rough structure, so as to increase the contact area between the substrate and the SiO₂ precursor solution. Controlling the parameters of the columnar structures can take into account the effects of the roughness and wettability of the substrate. The SiO₂ precursor solution is completely covered on the surface of the reentrant structure by spraying method and cured to obtain the superhydrophobic and superoleophobic coating. The SiO₂ precursor solution is obtained by modifying SiO₂ particles with a low surface energy surfactant, which not only ensures the low surface energy characteristics of the coating, but also increases the roughness of the coating, improving the superhydrophobic and superoleophobic properties, stability and durability of the superhydrophobic and superoleophobic coating. It is simple and economical and can be widely applied, especially in preventing metal corrosion in the ocean.

Description

Technical Field

[0001] The present invention belongs to the field of superhydrophobic and superoleophobic functional materials, and particularly relates to a superhydrophobic and superoleophobic coating with a columnar structure, a preparation method thereof, and an application thereof. Background Art

[0002] Existing anti-corrosion coatings have high costs, complex processes, and some materials are volatile and harmful to marine organisms. Moreover, most of the existing materials can only achieve hydrophobicity and are difficult to achieve oleophobicity. However, there is a lot of floating oil in the ocean. If only hydrophobicity is achieved without oleophobicity, the oil will pollute and adhere to the anti-corrosion coating, reducing the mechanical stability of the coating and shortening the service life of the coating. Therefore, it is necessary to manufacture a superhydrophobic and superoleophobic coating that can simultaneously have superhydrophobic and superoleophobic properties to improve the anti-corrosion life of metals in the ocean.

[0003] The main defects of existing superhydrophobic and superoleophobic coatings are as follows: A micro-nano structure introducing a micron-sized concave corner feature is used to prepare a superhydrophobic and superoleophobic coating by combining a micro-nano structure and a low surface energy component through an oxidation process, so that an air layer is formed between the oil droplet and the micro-nano structure, and the oil droplet has the characteristic of freely rolling on the surface of the structure. If the surface of the micro-nano structure is not completely attached by the low surface energy component, or the low surface energy component enters the micro-nano structure to affect the wettability, the superhydrophobic and superoleophobic properties will be weakened, and the mechanical stability does not meet the ideal requirements after undergoing water and oil immersion and impact tests. Since the sea waves in seawater will always give an impact force to the coating, the stability and durability of the superhydrophobic and superoleophobic coating are difficult to meet the application requirements.

[0004] Secondly, the oleophobic property of the low surface energy component of the superhydrophobic and superoleophobic coating is not good. Under the invasion of oil stains for many times, the coating gradually shows oleophilicity. For example, this situation often occurs in crude oil pipelines. If the time is too long, crude oil will adhere to the pipeline, which will cause pipeline blockage and reduction of service life.

[0005] In addition, expensive materials and processing methods are used in the preparation of the superhydrophobic and superoleophobic coating. For example, methods such as using templates and lithography to precisely prepare a bio-inspired superhydrophobic coating with a re-entrant geometry are currently proposed. However, these methods require complex procedures, expensive equipment, and specific substrates, which limit the large-scale production and practical application of the coating. Therefore, the manufacturing cost is relatively high, which is not conducive to the wide use of the superhydrophobic and superoleophobic coating. Summary of the Invention

[0006] The present invention aims to solve at least one of the above technical problems to some extent. The present invention provides a superhydrophobic and superoleophobic coating with a columnar structure, a preparation method thereof, and an application thereof, which improve the superhydrophobic and superoleophobic properties, stability, and durability of the superhydrophobic and superoleophobic coating, are simple and economical, and can be widely applied, especially in preventing metal corrosion in the ocean.

[0007] The technical solution adopted by the present invention to solve its technical problems is as follows:

[0008] A superhydrophobic and superoleophobic coating with a columnar structure, including a substrate. The surface of the substrate has an array composed of a number of columnar structures. The spacing between adjacent columnar structures is 120 - 400 μm, the height of the columnar structures is 150 - 500 μm, and the diameter of the columnar structures is 100 - 300 μm. Nano-ZnO needle-like structures are grown on the surface of the columnar structures to form a re-entrant structure, and the surface of the re-entrant structure is completely covered with a cured SiO2 precursor solution, which is obtained by modifying SiO2 particles with a low surface energy surfactant.

[0009] Due to the change in the microstructure of the substrate surface caused by the columnar structures, the roughness of the substrate surface is increased, so the superhydrophobic and superoleophobic properties of the coating are enhanced. The parameters of the above columnar structure array affect the superhydrophobic and superoleophobic properties of the coating, and its design basis is as follows:

[0010] (1) Spacing between adjacent columnar structures: The diameter of the columnar structures is 100 - 300 μm. If the spacing ≤ 120 μm, the SiO2 particles cannot completely cover the surface of the spacing between the columnar structures, and the superhydrophobic and superoleophobic properties of the coating surface are weakened; if the spacing ≥ 400 μm, it will cause a decrease in the roughness of the substrate surface, and the substrate surface roughness will affect the wettability of the coating, then the superhydrophobic and superoleophobic properties of the coating surface are weakened; further, the spacing between adjacent columnar structures is preferably 150 - 300 μm. In the preferred range, the water contact angle of water on the surface of this superhydrophobic and superoleophobic coating ≥ 160.5°, the contact angle of glycerol ≥ 154°, the contact angle of ethylene glycol ≥ 153°, and the contact angle of soybean oil ≥ 151°.

[0011] (2) Height of the columnar structures: The diameter of the columnar structures is 100 - 300 μm. If the height ≥ 500 μm, droplets will enter the gaps between the columnar structures, and the superhydrophobic and superoleophobic properties of the coating surface are weakened; if the height ≤ 150 μm, it will cause a decrease in the roughness of the substrate surface, and the surface roughness will affect the wettability of the coating, then the superhydrophobic and superoleophobic properties of the coating surface are weakened; further, the height of the columnar structures is preferably 200 - 400 μm. In the preferred range, the water contact angle of water on the surface of this superhydrophobic and superoleophobic coating ≥ 160°, the contact angle of glycerol ≥ 154°, the contact angle of ethylene glycol ≥ 152.5°, and the contact angle of soybean oil ≥ 151°.

[0012] The coating is not only used for the protection of metal substrates, but can be used for various material substrates. Further, the substrate is an Al alloy substrate; on the one hand, the Al alloy substrate is small in mass, convenient to carry, has good wear resistance and ductility, and has a high number of reusable times, and can be easily shaped into rectangular, cylindrical, conical and other shapes to meet the needs of various scenarios; on the other hand, a large proportion of the industrial machinery and equipment used in the ocean is made of Al alloy. Selecting an Al alloy substrate as the substrate facilitates the application of the coating to prevent metal corrosion in the ocean.

[0013] Furthermore, a conformal coating layer is provided between the surface of the reentrant structure and the solidified SiO2 precursor liquid. The conformal coating layer can further stably adhere the SiO2 particles modified with a low surfactant to the surface of the reentrant structure, thereby enhancing the robustness of the superamphiphobic coating.

[0014] Furthermore, if the ratio of the volume of the SiO2 precursor liquid to the area of the re-entrant structure surface is too small, the SiO2 particles may not be completely and evenly covered on the microscopic surface of the substrate, and the super-amphiphobicity of the coating will be weakened. If the ratio of the volume of the SiO2 precursor liquid to the area of the re-entrant structure surface is too large, the coating may easily crack during the curing process, thereby affecting the mechanical stability of the coating. The ratio of the volume of the SiO2 precursor liquid to the area of the re-entrant structure surface is (0.2-0.6) mL:4 cm 2 , can be further preferably (0.3~0.5)mL:4cm 2 , further improving the superamphiphobicity and mechanical stability of the coating.

[0015] Furthermore, the low surfactant is H,1H,2H,2H-perfluorodecyltriethoxysilane, and the SiO2 precursor liquid is a fluorinated SiO2 nanoparticle suspension.

[0016] Tetraethoxysilane will accelerate the hydrolysis to form SiO2 in alkaline solution. H,1H,2H,2H-perfluorodecyltriethoxysilane will graft the hydroxyl perfluorodecyltriethoxysilane to the SiO2 surface through condensation reaction, providing low surface energy groups. A large number of low surface energy groups -CF3 and -CF2 are successfully grafted onto the surface of the SiO2 filler. Due to the appropriate rough structure combined with the low surface energy groups, a durable air layer can be formed, which further makes the coating have excellent crude oil water repellency.

[0017] Further, if the proportion of SiO2 nanoparticles or tetraethoxysilane is too small, it is likely that the SiO2 particles cannot completely and evenly cover the re-entrant structure surface of the substrate, resulting in a weakening of the superhydrophobic and superoleophobic properties of the coating. If the proportion of SiO2 nanoparticles or tetraethoxysilane is too large, the SiO2 particles are likely to be unevenly distributed when covering the re-entrant structure surface of the substrate, leading to a reduction in the superhydrophobic and superoleophobic properties of the coating surface. If the proportion of H,1H,2H,2H-perfluorodecyltriethoxysilane is too small, low surface energy groups such as -CF3 and -CF2 are not easily grafted onto the SiO2 surface completely, reducing the superhydrophobic and superoleophobic properties of the coating surface. If the proportion of H,1H,2H,2H-perfluorodecyltriethoxysilane is too large, it will cause waste of resources and increase unnecessary costs. Therefore, the SiO2 precursor solution includes SiO2 nanoparticles and a low surface energy surfactant, and the mass ratio of SiO2 nanoparticles, absolute ethanol, ammonia water, tetraethoxysilane, and H,1H,2H,2H-perfluorodecyltriethoxysilane is: (2 - 2.5):(12 - 15):100:(2 - 2.5):(1 - 1.25), which can balance the cost and further improve the superhydrophobic and superoleophobic properties of the coating.

[0018] The preparation method of the above superhydrophobic and superoleophobic coating with a columnar structure includes:

[0019] Using laser engraving to prepare an array composed of several columnar structures on the substrate surface;

[0020] Using hydrothermal synthesis to grow nano-ZnO needle-like structures on the columnar structure surface;

[0021] Spraying the SiO2 precursor solution on the re-entrant structure surface and then curing to obtain the superhydrophobic and superoleophobic coating.

[0022] Using laser engraving to construct columnar microstructures and combining with hydrothermal synthesis to grow nano-ZnO needle-like structures to generate re-entrant structures, which can form a solid-liquid-gas composite interface. By constructing a multi-level rough structure, the stability and durability of the superhydrophobic and superoleophobic coating can be enhanced. Spraying the SiO2 precursor modified by a low surface energy surfactant on the re-entrant structure surface of the substrate, the functionalized particles and polymers have the advantages of simple manufacturing, economy, and scalability, facilitating wide application.

[0023] Further, it includes preparing the SiO2 precursor solution. The method for preparing the SiO2 precursor solution includes: dispersing SiO2 nanoparticles in absolute ethanol and ammonia water solution, magnetically stirring and mixing evenly at room temperature, then ultrasonically stirring for 5 - 10 min, and subsequently adding tetraethoxysilane and H,1H,2H,2H-perfluorodecyltriethoxysilane, and magnetically stirring for 1.5 - 2.5 h, which can form a fluorinated SiO2 nanoparticle suspension, and the preparation is simple and economical.

[0024] Further, the substrate is ultrasonically treated in absolute ethanol for 10 - 20 min. After taking out the substrate and drying it in a blower, the surface of the substrate can be cleaned, facilitating the combination of the columnar structure and the substrate. Then, a columnar structure is engraved on the surface of the substrate with a laser engraving machine. After laser engraving, the ultrasonic treatment operation can be repeated to clean the surface of the substrate, facilitating the combination of the columnar structure and nano-ZnO.

[0025] Further, the hydrothermal synthesis method includes:

[0026] Take isopropanol and zinc acetate, heat and mix them evenly at 70 - 90 °C, add triethylamine and react fully to obtain a ZnO seed solution. The mass ratio of isopropanol, zinc acetate to triethylamine is: (2 - 2.5):(2.5 - 3):100;

[0027] Take the ZnO seed solution and the substrate with a columnar structure, react at 85 - 95 °C for 1 - 2 h. After taking out the substrate and rinsing it, then react at 100 - 120 °C for 2 - 4 h to grow nano-ZnO needle-like structures on the surface of the columnar structure to form a reentrant structure.

[0028] Isopropanol is used as a solvent, zinc acetate is used as a precursor solution, and triethylamine is used as a stabilizer. If the proportion of zinc acetate and triethylamine is too small, it is easy to cause insufficient Zn 2+ ion concentration, affecting the crystallization of ZnO. If the proportion of zinc acetate and triethylamine is too large, it will cause waste of resources and increase unnecessary costs; the ZnO seed solution can be obtained by continuous reaction for 8 - 15 min. When the ZnO seed solution undergoes hydrothermal reaction with the substrate, when the Zn 2+ ions and OH - ion concentration reaches a certain critical value, ZnO crystal nuclei begin to form, and subsequent crystal growth on the crystal nuclei can occur. 40 - 60 mL of ZnO seed solution reacts with a 4 cm 2 substrate, and nano-needle-like structures can be successfully prepared.

[0029] Further, it includes spraying a three-proof paint solution on the surface of the reentrant structure, heating and curing to obtain a three-proof paint layer, and then spraying a SiO2 precursor solution on the surface of the three-proof paint layer, heating and curing to obtain a superhydrophobic and oleophobic coating; the three-proof paint solution can be sprayed at a distance of 10 - 15 cm with N2 at 0.25 Mpa at room temperature, and the substrate can be placed on a heating plate to heat and cure the three-proof paint solution, which has the advantage of simple preparation and can enhance the robustness of the superhydrophobic and oleophobic coating.

[0030] Regarding the application of the above superhydrophobic and oleophobic coating with a columnar structure, the superhydrophobic and oleophobic coating is arranged on the metal surface to prevent water and oil from adhering to the metal surface and corroding the metal.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] (1) An array composed of several columnar structures is constructed on the substrate surface. Nano-ZnO needle-like structures are grown on the surface of the columnar structures to generate a re-entrant structure, constructing a multi-level rough structure. Controlling the parameters of the columnar structures can balance the influence of the roughness and wettability of the substrate, increase the contact area between the substrate and the SiO2 precursor solution, enabling the SiO2 particles in the SiO2 precursor solution to better adhere to the surface of the re-entrant structure. This further increases the mechanical stability of the coating. At the same time, the SiO2 precursor solution modified by a low surface energy surfactant not only ensures the low surface energy characteristics of the coating, but also the SiO2 particles increase the roughness of the coating. The complete coverage of the SiO2 particles can improve the superhydrophobic and superoleophobic properties, thereby enhancing the superhydrophobicity, stability, and durability of the superhydrophobic coating. The water contact angle on the surface of this superhydrophobic coating can reach ≥150°, the contact angle of glycerol ≥146°, the contact angle of ethylene glycol ≥144°, and the contact angle of soybean oil ≥141°.

[0033] (2) H,1H,2H,2H-perfluorodecyltriethoxysilane is used to modify the SiO2 particles to form a fluorinated SiO2 nanoparticle suspension, promoting the superhydrophobic and superoleophobic properties of the surface and improving the superoleophobic property of the coating. Affected by wettability, water, glycerol, and ethylene glycol can roll off the substrate freely at 10°. Controlling the proportion of the low surface energy surfactant component and the volume ratio of the SiO2 precursor solution to the surface area of the re-entrant structure can further improve the mechanical stability and superhydrophobicity of the coating.

[0034] (3) Combining laser engraving, hydrothermal synthesis, and spraying methods to prepare the superhydrophobic coating, the raw materials are cheaper than those of existing superhydrophobic coating preparation methods, the manufacturing is simple, economical, and easy to mass-produce and promote.

[0035] (4) An Al alloy substrate can be used, which has the advantages of a small structural mass, convenient to carry, good wear resistance, long-term resistance to water and oil erosion, a high number of reusable times, and its corrosion voltage is lower than that of the Al alloy matrix; the corrosion current density of the superhydrophobic coating is lower than that of the Al alloy matrix, which can meet the requirements of various occasions, especially being convenient to be applied to prevent metal corrosion in the ocean. Description of the Drawings

[0036] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, where:

[0037] Figure 1 It is a measurement diagram of the water contact angle on the superhydrophobic coating in Embodiment 2 of the present invention.

[0038] Figure 2 It is a measurement diagram of the soybean oil contact angle on the superhydrophobic coating in Embodiment 3 of the present invention.

[0039] Figure 3It is the SEM image of the superhydrophobic and superoleophobic coating in Embodiment 3 of the present invention, and it can be seen that the SiO2 particles are completely covered.

[0040] Figure 4 It is the SEM image of the superhydrophobic and superoleophobic coating in Comparative Example 1 of the present invention, and it can be seen that the SiO2 particles are not completely covered. Detailed implementation manners

[0041] The embodiments of the present invention will be described in detail below. The examples are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0042] The materials and reagents used in the following examples are described:

[0043] The diameter of the SiO2 nanoparticles is 10 - 20 nm; the purity of tetraethoxysilane (TEOS) is 99.9%, and the purity of H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES) is 97%; the concentration of ammonia water is 25 - 28 wt%; the three-proof paint solution TN-4011 is purchased from Shenzhen Tinglan Industrial Co., Ltd.

[0044] Example 1:

[0045] A preferred implementation manner of the preparation method of the superhydrophobic and superoleophobic coating with a columnar structure according to the present invention includes the following steps:

[0046] S1. Prepare the SiO2 precursor solution: Disperse 1.0 g of SiO2 nanoparticles in 44 mL of absolute ethanol and 6 mL of ammonia water solution, magnetically stir for 30 min at room temperature to mix evenly, then ultrasonically stir for 5 min, and then add 1.0 mL of tetraethoxysilane and 0.5 mL of H,1H,2H,2H-perfluorodecyltriethoxysilane, and magnetically stir for 2 h to form a fluorinated SiO2 nanoparticle suspension as the SiO2 precursor solution;

[0047] S2. Prepare the substrate: Place a 4 cm 2 Al alloy substrate in absolute ethanol and ultrasonically treat it for 20 min. Take out the Al alloy substrate and dry it in a blower at 60 °C;

[0048] S3. Prepare the columnar structure: Use a laser engraving machine to punch an array composed of several columnar structures on the Al alloy substrate treated in step S2. The spacing between adjacent columnar structures is 120 μm, the height of the columnar structures is 300 μm, and the diameter of the columnar structures is 100 μm. Take the Al alloy substrate and repeat the treatment in step S2;

[0049] S4. Growth of ZnO nano-needle structures: 50 mL of isopropanol and 1.1 g of zinc acetate were added to a flask, which was heated at 85°C and stirred under magnetic stirring for 15 minutes. 1.4 mL of triethylamine was added to the flask, and the reaction was started and continued for 10 minutes to obtain a ZnO seed solution. The Al alloy substrate treated in step S3 and 50 mL of the ZnO seed solution were transferred to a Teflon autoclave, sealed, and heated at 90°C for 1 hour. The Al alloy substrate was then removed and rinsed with deionized water, and heated again at 100°C for 3 hours to grow nano-ZnO needle structures on the surface of the columnar structure.

[0050] S5. Preparation of a super amphiphobic coating: The Al alloy substrate treated in step S4 was sprayed with 1.0 mL of the conformal coating solution at a distance of 15 cm using 0.25 MPa N2 at room temperature and allowed to stand at room temperature for 10 min. The Al alloy substrate was then placed on a 150°C hot plate and heated for 5 min. After heat curing, a conformal coating layer was obtained. 0.4 mL of the SiO2 precursor liquid prepared in step S1 was sprayed on the conformal coating layer according to the same operation method as for spraying the conformal coating solution. After spraying, the substrate was cured at 60°C for 2 h to obtain an Al alloy super amphiphobic coating.

[0051] Wettability experiment of super-amphiphobic coating: The above-mentioned Al alloy super-amphiphobic coating was placed on a 10° inclined plane, and droplets of water, glycerol, ethylene glycol and soybean oil were placed on the coating with a dropper. The experiment was repeated 20 times, and all the droplets could slide off the coating quickly. Then, the contact angle of the Al alloy super-amphiphobic coating to water, glycerol, ethylene glycol and soybean oil was measured by a contact angle meter. The average value of the 20 experimental measurements showed that the contact angle of water was 152.5°, the contact angle of glycerol was 148.9°, the contact angle of ethylene glycol was 147.6°, and the contact angle of soybean oil was 144.2°. Its corrosion voltage was -0.706V, and the corrosion current density was 1.951×10 -5 A.cm -2 ; After soaking in 3.5% NaCl solution for 36 hours, the contact angle of water was measured to be 150.2°, the contact angle of glycerol was 148.4°, the contact angle of ethylene glycol was 145°, and the contact angle of soybean oil was 144.5°; after soaking in soybean oil for 36 hours, the contact angle of water was measured to be 148.1°, the contact angle of glycerol was 147.5°, the contact angle of ethylene glycol was 145.1°, and the contact angle of soybean oil was 143.6°.

[0052] Embodiment 2:

[0053] A preferred embodiment of the preparation method of the superhydrophobic and superoleophobic coating with a columnar structure according to the present invention. The difference between the obtained Al alloy superhydrophobic and superoleophobic coating and that of Example 1 lies in: S3. Preparation of columnar structure: The distance between adjacent columnar structures is 150 μm, the height of the columnar structure is 300 μm, and the diameter of the columnar structure is 100 μm.

[0054] Wettability experiment of the superhydrophobic and superoleophobic coating: Place the above-mentioned Al alloy superhydrophobic and superoleophobic coating on a 10° inclined plane, and use a dropper to place droplets of water, glycerol, ethylene glycol, and soybean oil on the coating respectively. Conduct the experiment 20 times, and all droplets can quickly slide off the coating; then use an instrument to measure the contact angles of the Al alloy superhydrophobic and superoleophobic coating with respect to water, glycerol, ethylene glycol, and soybean oil. After conducting the experiment and measuring 20 times and taking the average, it can be obtained that the water contact angle is 160.8°, the contact angle of glycerol is 154.4°, the contact angle of ethylene glycol is 153.1°, and the contact angle of soybean oil is 151.2°; its corrosion voltage is -0.930 V, and the corrosion current density is 4.980×10 -6 A·cm -2 ; After soaking in 3.5% NaCl solution for 36 h, the measured water contact angle is 157.2°, the contact angle of glycerol is 155.4°, the contact angle of ethylene glycol is 153.1°, and the contact angle of soybean oil is 151.5°. After soaking in soybean oil for 36 h, the measured water contact angle is 156.4°, the contact angle of glycerol is 154.5°, the contact angle of ethylene glycol is 152.6°, and the contact angle of soybean oil is 150.6°.

[0055] Example 3:

[0056] A preferred embodiment of the preparation method of the superhydrophobic and superoleophobic coating with a columnar structure according to the present invention. The difference between the obtained Al alloy superhydrophobic and superoleophobic coating and that of Example 1 lies in: S3. Preparation of columnar structure: The distance between adjacent columnar structures is 250 μm, the height of the columnar structure is 300 μm, and the diameter of the columnar structure is 100 μm.

[0057] Wettability experiment of the superhydrophobic and superoleophobic coating: Place the above-mentioned Al alloy superhydrophobic and superoleophobic coating on a 10° inclined plane, and use a dropper to place droplets of water, glycerol, ethylene glycol, and soybean oil on the coating respectively. Conduct the experiment 20 times, and all droplets can quickly slide off the coating; then use an instrument to measure the contact angles of the Al alloy superhydrophobic and superoleophobic coating with respect to water, glycerol, ethylene glycol, and soybean oil. After conducting the experiment and measuring 20 times and taking the average, it can be obtained that the water contact angle is 161.6°, the contact angle of glycerol is 155.6°, the contact angle of ethylene glycol is 153.9°, and the contact angle of soybean oil is 152.0°; its corrosion voltage is -0.925 V, and the corrosion current density is 3.45×10 -6 A·cm -2; After soaking in 3.5% NaCl solution for 36 h, the water contact angle was measured to be 159.2°, the contact angle of glycerol was 152.4°, the contact angle of ethylene glycol was 151.1°, and the contact angle of soybean oil was 150.5°; after soaking in soybean oil for 36 h, the water contact angle was measured to be 158.4°, the contact angle of glycerol was 151.9°, the contact angle of ethylene glycol was 150.8°, and the contact angle of soybean oil was 150.1°.

[0058] Comparative Example 1:

[0059] A preparation method of a superhydrophobic and superoleophobic coating, the obtained Al alloy superhydrophobic and superoleophobic coating by this method is different from that in Example 3 in that: S3. Prepare columnar structures: the spacing between adjacent columnar structures is 50 μm, the height of the columnar structure is 300 μm, and the diameter of the columnar structure is 100 μm.

[0060] Superhydrophobic and superoleophobic coating wettability experiment: Place the above-mentioned Al alloy superhydrophobic and superoleophobic coating on a 10° inclined plane, and use a dropper to place droplets of water, glycerol, ethylene glycol, and soybean oil on the coating respectively. Conduct the experiment 20 times, and all droplets can slide off the coating, but the sliding speed is very slow; then use an instrument to measure the contact angles of the Al alloy superhydrophobic and superoleophobic coating with water, glycerol, ethylene glycol, and soybean oil. The average value obtained by conducting the experiment and measuring 20 times can show that the water contact angle is 128.1°, the contact angle of glycerol is 122.4°, the contact angle of ethylene glycol is 116.8°, and the contact angle of soybean oil is 114.5°; its corrosion voltage is -0.048 V, and the corrosion current density is 6.221×10 - 5 A·cm -2 ; After soaking in 3.5% NaCl solution for 36 h, the water contact angle was measured to be 125.2°, the contact angle of glycerol was 120.4°, the contact angle of ethylene glycol was 113.1°, and the contact angle of soybean oil was 111.5°; after soaking in soybean oil for 36 h, the water contact angle was measured to be 124.4°, the contact angle of glycerol was 119.5°, the contact angle of ethylene glycol was 112.6°, and the contact angle of soybean oil was 110.6°.

[0061] The comparison results between Example 3 and Comparative Example 1 show that the too small spacing between the columnar structures on the substrate surface is not conducive to the complete coverage of the surface between the spacings by SiO2 particles during spraying, so the superhydrophobic and superoleophobic properties of the coating will be weakened.

[0062] Comparative Example 2:

[0063] A preparation method of a superhydrophobic and superoleophobic coating, the obtained Al alloy superhydrophobic and superoleophobic coating by this method is different from that in Example 3 in that: S3. Prepare columnar structures: the spacing between adjacent columnar structures is 500 μm, the height of the columnar structure is 300 μm, and the diameter of the columnar structure is 100 μm.

[0064] Superhydrophobic and oleophobic coating wettability experiment: Place the above-mentioned superhydrophobic and oleophobic Al alloy coating on a 10° inclined plane, and use a dropper to place droplets of water, glycerol, ethylene glycol, and soybean oil on the coating respectively. Conduct the experiment 20 times, and all droplets can slide off the coating, but the sliding speed is very slow; then use an instrument to measure the contact angles of the superhydrophobic and oleophobic Al alloy coating with water, glycerol, ethylene glycol, and soybean oil. By averaging the experimental measurements 20 times, the water contact angle can be obtained as 132.3°, the glycerol contact angle as 126.7°, the ethylene glycol contact angle as 121.9°, and the soybean oil contact angle as 119.5°; its corrosion voltage is -0.161 V, and the corrosion current density is 5.486×10 - 5 A·cm -2 ; After soaking in 3.5% NaCl solution for 36 h, the measured water contact angle is 129.2°, the glycerol contact angle is 123.4°, the ethylene glycol contact angle is 118.1°, and the soybean oil contact angle is 116.5°. After soaking in soybean oil for 36 h, the measured water contact angle is 128.4°, the glycerol contact angle is 122.5°, the ethylene glycol contact angle is 117.6°, and the soybean oil contact angle is 115.6°.

[0065] The comparison results between Example 3 and Comparative Example 2 show that if the distance between the columnar structures on the substrate surface is too large, the surface roughness will decrease, and the surface roughness will affect the wettability of the coating. Therefore, the superhydrophobic and oleophobic properties of the coating will be weakened.

[0066] Example 4:

[0067] A preferred implementation method of the preparation method of the superhydrophobic and oleophobic coating with columnar structures according to the present invention. The difference between the obtained superhydrophobic and oleophobic Al alloy coating and that in Example 1 is as follows: S3. Prepare columnar structures: The distance between adjacent columnar structures is 300 μm, the height of the columnar structures is 300 μm, and the diameter of the columnar structures is 100 μm.

[0068] Superhydrophobic and oleophobic coating wettability experiment: Place the above-mentioned superhydrophobic and oleophobic Al alloy coating on a 10° inclined plane, and use a dropper to place droplets of water, glycerol, ethylene glycol, and soybean oil on the coating respectively. Conduct the experiment 20 times, and all droplets can slide off the coating quickly; then use an instrument to measure the contact angles of the superhydrophobic and oleophobic Al alloy coating with water, glycerol, ethylene glycol, and soybean oil. By averaging the experimental measurements 20 times, the water contact angle can be obtained as 161.3°, the glycerol contact angle as 154.8°, the ethylene glycol contact angle as 153.4°, and the soybean oil contact angle as 151.5°; its corrosion voltage is -0.944 V, and the corrosion current density is 4.105×10 -6 A·cm -2; After soaking in 3.5% NaCl solution for 36 h, the measured water contact angle was 158.6°, the contact angle of glycerol was 152.1°, the contact angle of ethylene glycol was 151.3°, and the contact angle of soybean oil was 150.3°; after soaking in soybean oil for 36 h, the measured water contact angle was 158.1°, the contact angle of glycerol was 151.5°, the contact angle of ethylene glycol was 150.6°, and the contact angle of soybean oil was 149.8°.

[0069] Example 5:

[0070] A preferred embodiment of the preparation method of the super-biphobic coating with a columnar structure according to the present invention. The difference between the obtained Al alloy super-biphobic coating and that of Example 1 lies in: S3. Preparation of columnar structure: the distance between adjacent columnar structures is 400 μm, the height of the columnar structure is 300 μm, and the diameter of the columnar structure is 100 μm.

[0071] Wettability experiment of the super-biphobic coating: Place the above-mentioned Al alloy super-biphobic coating on a 10° inclined plane, and use a dropper to place droplets of water, glycerol, ethylene glycol, and soybean oil on the coating respectively. Conduct the experiment 20 times, and all droplets can quickly slide off the coating; then use an instrument to measure the contact angles of the Al alloy super-biphobic coating with respect to water, glycerol, ethylene glycol, and soybean oil. The average value obtained by measuring 20 times shows that the water contact angle is 150.2°, the contact angle of glycerol is 146.7°, the contact angle of ethylene glycol is 144.3°, and the contact angle of soybean oil is 141.8°; its corrosion voltage is -0.644 V, and the corrosion current density is 2.353×10 -5 A·cm -2 ; After soaking in 3.5% NaCl solution for 36 h, the measured water contact angle was 147.2°, the contact angle of glycerol was 145.4°, the contact angle of ethylene glycol was 144.1°, and the contact angle of soybean oil was 141.9°; after soaking in soybean oil for 36 h, the measured water contact angle was 146.4°, the contact angle of glycerol was 144.5°, the contact angle of ethylene glycol was 143.6°, and the contact angle of soybean oil was 140.6°.

[0072] Example 6:

[0073] A preferred embodiment of the preparation method of the super-biphobic coating with a columnar structure according to the present invention. The difference between the obtained Al alloy super-biphobic coating and that of Example 1 lies in: S3. Preparation of columnar structure: the distance between adjacent columnar structures is 200 μm, the height of the columnar structure is 150 μm, and the diameter of the columnar structure is 100 μm.

[0074] Superhydrophobic and oleophobic coating wettability experiment: Place the above-mentioned Al alloy superhydrophobic and oleophobic coating on a 10° inclined plane, and use a dropper to place droplets of water, glycerol, ethylene glycol, and soybean oil on the coating respectively. Conduct the experiment 20 times, and all droplets can quickly slide off the coating. Then use an instrument to measure the contact angles of the Al alloy superhydrophobic and oleophobic coating with water, glycerol, ethylene glycol, and soybean oil. After conducting the experiment 20 times and taking the average value, the water contact angle can be obtained as 155.1°, the contact angle of glycerol is 151.8°, the contact angle of ethylene glycol is 150.3°, and the contact angle of soybean oil is 148.9°. Its corrosion voltage is -0.777V, and the corrosion current density is 1.502×10 -5 A·cm -2 ; After soaking in 3.5% NaCl solution for 36h, the measured water contact angle is 153.3°, the contact angle of glycerol is 150.9°, the contact angle of ethylene glycol is 148.2°, and the contact angle of soybean oil is 147.6°; After soaking in soybean oil for 36h, the measured water contact angle is 151.9°, the contact angle of glycerol is 149.8°, the contact angle of ethylene glycol is 147.6°, and the contact angle of soybean oil is 146.5°.

[0075] Example 7:

[0076] A preferred implementation of the preparation method of the superhydrophobic and oleophobic coating with a columnar structure described in the present invention. The difference between the obtained Al alloy superhydrophobic and oleophobic coating and that of Example 1 is as follows: S3. Preparation of columnar structure: The spacing between adjacent columnar structures is 200μm, the height of the columnar structure is 200μm, and the diameter of the columnar structure is 100μm.

[0077] Superhydrophobic and oleophobic coating wettability experiment: Place the above-mentioned Al alloy superhydrophobic and oleophobic coating on a 10° inclined plane, and use a dropper to place droplets of water, glycerol, ethylene glycol, and soybean oil on the coating respectively. Conduct the experiment 20 times, and all droplets can quickly slide off the coating. Then use an instrument to measure the contact angles of the Al alloy superhydrophobic and oleophobic coating with water, glycerol, ethylene glycol, and soybean oil. After conducting the experiment 20 times and taking the average value, the water contact angle can be obtained as 161.1°, the contact angle of glycerol is 154.9°, the contact angle of ethylene glycol is 153.3°, and the contact angle of soybean oil is 151.4°. Its corrosion voltage is -0.939V, and the corrosion current density is 4.455×10 -6 A·cm -2 ; After soaking in 3.5% NaCl solution for 36h, the measured water contact angle is 158.4°, the contact angle of glycerol is 151.9°, the contact angle of ethylene glycol is 151.0°, and the contact angle of soybean oil is 150.1°; After soaking in soybean oil for 36h, the measured water contact angle is 157.8°, the contact angle of glycerol is 151.3°, the contact angle of ethylene glycol is 150.3°, and the contact angle of soybean oil is 149.5°.

[0078] Example 8:

[0079] A preferred embodiment of the preparation method of the superhydrophobic and superoleophobic coating with a columnar structure according to the present invention. The difference between the obtained Al alloy superhydrophobic and superoleophobic coating and that of Example 1 lies in: S3. Preparation of columnar structure: The spacing between adjacent columnar structures is 200 μm, the height of the columnar structure is 250 μm, and the diameter of the columnar structure is 100 μm.

[0080] Wettability experiment of the superhydrophobic and superoleophobic coating: Place the above-mentioned Al alloy superhydrophobic and superoleophobic coating on a 10° inclined plane, and use a dropper to place droplets of water, glycerol, ethylene glycol, and soybean oil on the coating respectively. Conduct the experiment 20 times, and all droplets can quickly slide off the coating; then use an instrument to measure the contact angles of the Al alloy superhydrophobic and superoleophobic coating with respect to water, glycerol, ethylene glycol, and soybean oil. After conducting the experiment and measuring 20 times and taking the average value, it can be obtained that the water contact angle is 162.3°, the contact angle of glycerol is 156.2°, the contact angle of ethylene glycol is 154.7°, and the contact angle of soybean oil is 153.3°; its corrosion voltage is -0.971 V, and the corrosion current density is 2.376×10 -6 A·cm -2 ; After soaking in 3.5% NaCl solution for 36 h, the measured water contact angle is 159.7°, the contact angle of glycerol is 153.4°, the contact angle of ethylene glycol is 152.2°, and the contact angle of soybean oil is 151.5°; after soaking in soybean oil for 36 h, the measured water contact angle is 159.1°, the contact angle of glycerol is 152.4°, the contact angle of ethylene glycol is 151.9°, and the contact angle of soybean oil is 150.5°.

[0081] Example 9:

[0082] A preferred embodiment of the preparation method of the superhydrophobic and superoleophobic coating with a columnar structure according to the present invention. The difference between the obtained Al alloy superhydrophobic and superoleophobic coating and that of Example 1 lies in: S3. Preparation of columnar structure: The spacing between adjacent columnar structures is 200 μm, the height of the columnar structure is 300 μm, and the diameter of the columnar structure is 100 μm.

[0083] Wettability experiment of the superhydrophobic and superoleophobic coating: Place the above-mentioned Al alloy superhydrophobic and superoleophobic coating on a 10° inclined plane, and use a dropper to place droplets of water, glycerol, ethylene glycol, and soybean oil on the coating respectively. Conduct the experiment 20 times, and all droplets can quickly slide off the coating; then use an instrument to measure the contact angles of the Al alloy superhydrophobic and superoleophobic coating with respect to water, glycerol, ethylene glycol, and soybean oil. After conducting the experiment and measuring 20 times and taking the average value, it can be obtained that the water contact angle is 160.9°, the contact angle of glycerol is 154.6°, the contact angle of ethylene glycol is 153.5°, and the contact angle of soybean oil is 151.4°; its corrosion voltage is -0.933 V, and the corrosion current density is 4.805×10 -6 A·cm -2; After soaking in 3.5% NaCl solution for 36 h, the measured water contact angle was 157.3°, the contact angle of glycerol was 155.6°, the contact angle of ethylene glycol was 153.3°, and the contact angle of soybean oil was 151.8°; After soaking in soybean oil for 36 h, the measured water contact angle was 156.6°, the contact angle of glycerol was 154.8°, the contact angle of ethylene glycol was 152.8°, and the contact angle of soybean oil was 150.9°.

[0084] Comparative Example 3:

[0085] A method for preparing a superhydrophobic and superoleophobic coating, the difference between the obtained Al alloy superhydrophobic and superoleophobic coating and that of Example 9 lies in: S3. Preparing columnar structures: the spacing between adjacent columnar structures is 200 μm, the height of the columnar structure is 50 μm, and the diameter of the columnar structure is 100 μm.

[0086] Superhydrophobic and superoleophobic coating wettability experiment: Place the above Al alloy superhydrophobic and superoleophobic coating on a 10° inclined plane, and use a dropper to place droplets of water, glycerol, ethylene glycol, and soybean oil on the coating respectively. Conduct the experiment 20 times, and all the droplets can slide off the coating, but the sliding speed is very slow; Then use an instrument to measure the contact angles of the Al alloy superhydrophobic and superoleophobic coating with water, glycerol, ethylene glycol, and soybean oil. The average value obtained by conducting the experiment and measuring 20 times can show that the water contact angle is 128.5°, the contact angle of glycerol is 117.3°, the contact angle of ethylene glycol is 114.6°, and the contact angle of soybean oil is 111.4°; Its corrosion voltage is -0.058 V, and the corrosion current density is 6.151×10 - 5 A·cm -2 ; After soaking in 3.5% NaCl solution for 36 h, the measured water contact angle was 125.9°, the contact angle of glycerol was 115.5°, the contact angle of ethylene glycol was 136.1°, and the contact angle of soybean oil was 109.1°; After soaking in soybean oil for 36 h, the measured water contact angle was 124.2°, the contact angle of glycerol was 114.8°, the contact angle of ethylene glycol was 111.5°, and the contact angle of soybean oil was 109.7°.

[0087] The comparison results between Example 9 and Comparative Example 3 show that if the height of the columnar structures on the coating surface is too small, it will lead to a decrease in surface roughness, and the surface roughness will affect the wettability of the coating. Therefore, the superhydrophobic and superoleophobic properties of the coating will be weakened.

[0088] Comparative Example 4:

[0089] A method for preparing a superhydrophobic and superoleophobic coating, the difference between the obtained Al alloy superhydrophobic and superoleophobic coating and that of Example 9 lies in: S3. Preparing columnar structures: the spacing between adjacent columnar structures is 200 μm, the height of the columnar structure is 600 μm, and the diameter of the columnar structure is 100 μm.

[0090] Superhydrophobic and oleophobic coating wettability experiment: Place the above-mentioned superhydrophobic and oleophobic coating on an Al alloy on a 10° inclined plane. Use a dropper to place droplets of water, glycerol, ethylene glycol, and soybean oil on the coating respectively. Conduct the experiment 20 times. All droplets can slide off the coating, but the sliding speed is very slow. Then use an instrument to measure the contact angles of the superhydrophobic and oleophobic coating on Al alloy with respect to water, glycerol, ethylene glycol, and soybean oil. After measuring 20 times and taking the average, the water contact angle is 129.8°, the contact angle of glycerol is 121.7°, the contact angle of ethylene glycol is 118.9°, and the contact angle of soybean oil is 115.5°; its corrosion voltage is -0.093V, and the corrosion current density is 5.764×10 - 5 A·cm -2 ⁻². After soaking in 3.5% NaCl solution for 36h, the measured water contact angle is 127.5°, the contact angle of glycerol is 118.8°, the contact angle of ethylene glycol is 116.2°, and the contact angle of soybean oil is 113.7°; after soaking in soybean oil for 36h, the measured water contact angle is 126.8°, the contact angle of glycerol is 118.1°, the contact angle of ethylene glycol is 115.5°, and the contact angle of soybean oil is 113.2°.

[0091] The comparison results between Example 9 and Comparative Example 4 show that if the height of the columnar structure on the coating surface is too large, it will cause the droplets to enter the gaps between the columnar structures, making the droplets unable to maintain a completely spherical shape. Therefore, the superhydrophobic and oleophobic properties of the coating will be weakened.

[0092] Example 10:

[0093] A preferred implementation of the preparation method of the superhydrophobic and oleophobic coating with columnar structure according to the present invention. The difference between the obtained Al alloy superhydrophobic and oleophobic coating and that of Example 1 is as follows: S3. Prepare columnar structures: The spacing between adjacent columnar structures is 200μm, the height of the columnar structure is 400μm, and the diameter of the columnar structure is 100μm.

[0094] Superhydrophobic and oleophobic coating wettability experiment: Place the above-mentioned Al alloy superhydrophobic and oleophobic coating on a 10° inclined plane. Use a dropper to place droplets of water, glycerol, ethylene glycol, and soybean oil on the coating respectively. Conduct the experiment 20 times. All droplets can slide off the coating quickly. Then use an instrument to measure the contact angles of the superhydrophobic and oleophobic coating on Al alloy with respect to water, glycerol, ethylene glycol, and soybean oil. After measuring 20 times and taking the average, the water contact angle is 160.5°, the contact angle of glycerol is 154.1°, the contact angle of ethylene glycol is 152.9°; the contact angle of soybean oil is 151.1°; its corrosion voltage is -0.921V, and the corrosion current density is 5.505×10 -6 A·cm -2; After soaking in 3.5% NaCl solution for 36 h, the water contact angle was measured to be 156.9°, the contact angle of glycerol was 155.2°, the contact angle of ethylene glycol was 152.9°, and the contact angle of soybean oil was 151.3°; After soaking in soybean oil for 36 h, the water contact angle was measured to be 156.1°, the contact angle of glycerol was 154.3°, the contact angle of ethylene glycol was 152.3°, and the contact angle of soybean oil was 150.3°.

[0095] Example 11:

[0096] A preferred embodiment of the preparation method of the superhydrophobic and superoleophobic coating with a columnar structure according to the present invention. The difference between the obtained Al alloy superhydrophobic and superoleophobic coating and that of Example 1 lies in: S3. Preparation of columnar structure: The spacing between adjacent columnar structures is 200 μm, the height of the columnar structure is 500 μm, and the diameter of the columnar structure is 100 μm.

[0097] Wettability experiment of the superhydrophobic and superoleophobic coating: Place the above Al alloy superhydrophobic and superoleophobic coating on a 10° inclined plane, and use a dropper to place droplets of water, glycerol, ethylene glycol, and soybean oil on the coating respectively. Conduct the experiment 20 times, and all droplets can quickly slide off the coating; Then use an instrument to measure the contact angles of the Al alloy superhydrophobic and superoleophobic coating with respect to water, glycerol, ethylene glycol, and soybean oil. The average value obtained by measuring 20 times experimentally shows that the water contact angle is 153.8°, the contact angle of glycerol is 149.7°, the contact angle of ethylene glycol is 147.9°, and the contact angle of soybean oil is 145.3°; Its corrosion voltage is -0.741 V, and the corrosion current density is 1.723×10 -5 A·cm -2 ; After soaking in 3.5% NaCl solution for 36 h, the water contact angle was measured to be 151.5°, the contact angle of glycerol was 149.6°, the contact angle of ethylene glycol was 146.2°, and the contact angle of soybean oil was 145.7°; After soaking in soybean oil for 36 h, the water contact angle was measured to be 149.4°, the contact angle of glycerol was 148.7°, the contact angle of ethylene glycol was 146.3°, and the contact angle of soybean oil was 144.8°.

[0098] Example 12:

[0099] A preferred embodiment of the preparation method of the superhydrophobic and superoleophobic coating with a columnar structure according to the present invention. The difference between the obtained Al alloy superhydrophobic and superoleophobic coating and that of Example 1 lies in: S3. Preparation of columnar structure: The spacing between adjacent columnar structures is 200 μm, the height of the columnar structure is 300 μm, and the diameter of the columnar structure is 100 μm; S5. Preparation of the superhydrophobic and superoleophobic coating: Spray 0.2 mL of the SiO2 precursor solution prepared in step S1 on the three-proof paint layer.

[0100] Superhydrophobic and oleophobic coating wettability experiment: Place the above-mentioned superhydrophobic and oleophobic Al alloy coating on a 10° inclined plane, and use a dropper to place droplets of water, glycerol, ethylene glycol, and soybean oil on the coating. Conduct the experiment 20 times, and all droplets can quickly slide off the coating. Then, use an instrument to measure the contact angles of the superhydrophobic and oleophobic Al alloy coating with respect to water, glycerol, ethylene glycol, and soybean oil. After conducting the experiment 20 times and taking the average, the water contact angle is 151.7°, the glycerol contact angle is 147.1°, the ethylene glycol contact angle is 146.3°, and the soybean oil contact angle is 143.5°. Its corrosion voltage is -0.685 V, and the corrosion current density is 2.091×10 -5 A·cm -2 ; After soaking in 3.5% NaCl solution for 36 h, the measured water contact angle is 149.1°, the glycerol contact angle is 147.2°, the ethylene glycol contact angle is 143.8°, and the soybean oil contact angle is 143.3°. After soaking in soybean oil for 36 h, the measured water contact angle is 146.8°, the glycerol contact angle is 146.2°, the ethylene glycol contact angle is 143.9°, and the soybean oil contact angle is 142.5°.

[0101] Example 13:

[0102] A preferred implementation of the method for preparing a superhydrophobic and oleophobic coating with a columnar structure according to the present invention. The difference between the obtained superhydrophobic and oleophobic Al alloy coating and that of Example 12 is as follows: S5. Prepare the superhydrophobic and oleophobic coating: Spray 0.3 mL of the SiO2 precursor solution prepared in step S1 on the three-proof paint layer.

[0103] Superhydrophobic and oleophobic coating wettability experiment: Place the above-mentioned superhydrophobic and oleophobic Al alloy coating on a 10° inclined plane, and use a dropper to place droplets of water, glycerol, ethylene glycol, and soybean oil on the coating. Conduct the experiment 20 times, and all droplets can quickly slide off the coating. Then, use an instrument to measure the contact angles of the superhydrophobic and oleophobic Al alloy coating with respect to water, glycerol, ethylene glycol, and soybean oil. After conducting the experiment 20 times and taking the average, the water contact angle is 161.3°, the glycerol contact angle is 155.1°, the ethylene glycol contact angle is 153.4°, and the soybean oil contact angle is 151.8°. Its corrosion voltage is -0.944 V, and the corrosion current density is 4.105×10 -6 A·cm -2 ; After soaking in 3.5% NaCl solution for 36 h, the measured water contact angle is 158.5°, the glycerol contact angle is 152.1°, the ethylene glycol contact angle is 151.4°, and the soybean oil contact angle is 150.3°. After soaking in soybean oil for 36 h, the measured water contact angle is 158.2°, the glycerol contact angle is 151.6°, the ethylene glycol contact angle is 150.5°, and the soybean oil contact angle is 149.9°.

[0104] Comparative Example 5:

[0105] A method for preparing a super-amphiphobic coating, wherein the Al alloy super-amphiphobic coating obtained by the method is different from that of Example 13 in that: S5, preparing a super-amphiphobic coating: spraying 0.1 mL of the SiO2 precursor liquid obtained in step S1 on the conformal coating layer.

[0106] Super-amphiphobic coating wettability experiment: The above-mentioned Al alloy super-amphiphobic coating was placed on a 10° inclined plane, and droplets of water, glycerol, ethylene glycol and soybean oil were placed on the coating with a dropper. The experiment was repeated 20 times. All droplets could slide off the coating, but the sliding speed was very slow. Then the contact angles of the Al alloy super-amphiphobic coating to water, glycerol, ethylene glycol and soybean oil were measured by an instrument. The average value of the 20 experimental measurements showed that the contact angles of water, glycerol, ethylene glycol and soybean oil were 131.4°, 123.3°, 120.5° and 118.3°, respectively. The corrosion voltage was -0.137 V, and the corrosion current density was 5.643×10 - 5 A.cm -2 After immersion in 3.5% NaCl solution for 36 hours, the contact angles of water, glycerol, ethylene glycol, and soybean oil were measured to be 128.5°, 120.6°, 117.4°, and 115.8°, respectively. After immersion in soybean oil for 36 hours, the contact angles of water, glycerol, ethylene glycol, and soybean oil were measured to be 127.3°, 119.7°, 116.8°, and 115.1°, respectively.

[0107] The comparison results of Example 13 and Comparative Example 5 show that if the ratio of the volume of the sprayed SiO2 precursor liquid to the area of the sprayed substrate is too small, the SiO2 particles will not be completely and evenly covered on the microscopic surface of the substrate, and thus the super amphiphobicity of the coating will be weakened.

[0108] Comparative Example 6:

[0109] A method for preparing a super-amphiphobic coating, wherein the Al alloy super-amphiphobic coating obtained by the method is different from that of Example 13 in that: S5, preparing a super-amphiphobic coating: spraying 0.7 mL of the SiO2 precursor liquid obtained in step S1 on the conformal coating layer.

[0110] Super-amphiphobic coating wettability experiment: The above-mentioned Al alloy super-amphiphobic coating was placed on a 10° inclined plane, and droplets of water, glycerol, ethylene glycol, and soybean oil were placed on the coating with a dropper. The experiment was repeated 20 times. All droplets were able to slide off the coating, but the sliding speed was very slow. Then, the contact angle of the Al alloy super-amphiphobic coating to water, glycerol, ethylene glycol, and soybean oil was measured by an instrument. The average value of the experimental measurement of 20 times showed that the contact angle of water was 127.7°, the contact angle of glycerol was 122.6°, the contact angle of ethylene glycol was 118.3°, and the contact angle of soybean oil was 116.2°. Its corrosion voltage was -0.037V, and the corrosion current density was 6.641×10 - 5 A.cm -2 ; After soaking in 3.5% NaCl solution for 36 hours, the contact angle of water was measured to be 122.9°, the contact angle of glycerol was 119.5°, the contact angle of ethylene glycol was 115.7°, and the contact angle of soybean oil was 113.6°; after soaking in soybean oil for 36 hours, the contact angle of water was measured to be 122.3°, the contact angle of glycerol was 119.0°, the contact angle of ethylene glycol was 115.1°, and the contact angle of soybean oil was 136.8°.

[0111] The comparison results of Example 13 and Comparative Example 6 show that if the ratio of the volume of the sprayed SiO2 precursor liquid to the area of the sprayed substrate is too large, the coating will dry and crack during the curing process of the SiO2 precursor liquid coating after spraying, reducing the mechanical stability of the coating, and thus the super amphiphobicity of the coating will be weakened.

[0112] Embodiment 14:

[0113] A preferred embodiment of the method for preparing a super-amphiphobic coating having a columnar structure described in the present invention, wherein the Al alloy super-amphiphobic coating obtained by the method differs from that in Example 12 in that: S5, preparing a super-amphiphobic coating: spraying 0.5 mL of the SiO2 precursor liquid obtained in step S1 on the conformal coating layer.

[0114] Super-amphiphobic coating wettability experiment: The above-mentioned Al alloy super-amphiphobic coating was placed on a 10° inclined plane, and droplets of water, glycerol, ethylene glycol and soybean oil were placed on the coating with a dropper. The experiment was repeated 20 times, and all the droplets could slide off the coating quickly. Then, the contact angles of the Al alloy super-amphiphobic coating to water, glycerol, ethylene glycol and soybean oil were measured by an instrument. The average value of the 20 experimental measurements showed that the contact angles of water, glycerol, ethylene glycol and soybean oil were 160.6°, 154.3°, 153.1° and 151.3°, respectively. The corrosion voltage was -0.925V, and the corrosion current density was 5.33×10 -6 A.cm -2; After soaking in 3.5% NaCl solution for 36 hours, the contact angle of water was measured to be 157.2°, the contact angle of glycerol was 155.3°, the contact angle of ethylene glycol was 152.9°, and the contact angle of soybean oil was 151.3°; after soaking in soybean oil for 36 hours, the contact angle of water was measured to be 156.1°, the contact angle of glycerol was 154.2°, the contact angle of ethylene glycol was 152.5°, and the contact angle of soybean oil was 150.3°.

[0115] Embodiment 15:

[0116] A preferred embodiment of the method for preparing a super-amphiphobic coating having a columnar structure described in the present invention, wherein the Al alloy super-amphiphobic coating obtained by the method differs from that in Example 12 in that: S5, preparing a super-amphiphobic coating: spraying 0.6 mL of the SiO2 precursor liquid obtained in step S1 on the conformal coating layer.

[0117] Super-amphiphobic coating wettability experiment: The above-mentioned Al alloy super-amphiphobic coating was placed on a 10° inclined plane, and droplets of water, glycerol, ethylene glycol and soybean oil were placed on the coating with a dropper. The experiment was repeated 20 times, and all the droplets could slide off the coating quickly. Then, the contact angles of the Al alloy super-amphiphobic coating to water, glycerol, ethylene glycol and soybean oil were measured by an instrument. The average value of the 20 experimental measurements showed that the contact angles of water, glycerol, ethylene glycol and soybean oil were 150.9°, 146.9°, 144.8° and 142.3°, respectively. The corrosion voltage was -0.663V, and the corrosion current density was 2.231×10 -5 A.cm -2 ; After soaking in 3.5% NaCl solution for 36 hours, the contact angle of water was measured to be 147.9°, the contact angle of glycerol was 146.2°, the contact angle of ethylene glycol was 144.9°, and the contact angle of soybean oil was 142.8°; after soaking in soybean oil for 36 hours, the contact angle of water was measured to be 147.1°, the contact angle of glycerol was 145.3°, the contact angle of ethylene glycol was 144.2°, and the contact angle of soybean oil was 141.3°.

[0118] In the above method, microscopic columnar structures are formed on the surface of the Al alloy substrate by a laser engraving machine. Due to the change of the surface microstructure, nano-ZnO needle-like structures grow on the surface of the columnar structures to form a re-entrant structure, constructing a multi-level rough structure. Controlling the parameters of the columnar structures can take into account the influence of the roughness and wettability of the substrate, increase the contact area between the substrate and the SiO2 precursor solution, so that the SiO2 particles in the SiO2 precursor solution can better adhere to the surface of the re-entrant structure, thereby increasing the mechanical stability of the coating. At the same time, the SiO2 precursor solution modified by a low surface energy surfactant not only ensures the low surface energy characteristics of the coating, but also the SiO2 particles increase the roughness of the coating. The complete coverage of the SiO2 particles can improve the superhydrophobic and superoleophobic properties, increasing the roughness of the substrate surface, so the superhydrophobic and superoleophobic properties of the coating are enhanced. The good superhydrophobic and superoleophobic properties can prevent metals from being corroded in seawater, and have the advantages of small structural mass, convenient to carry, good wear resistance and ductility.

[0119] In terms of the preparation method, spraying functional particles and polymers on the substrate has the advantages of simplicity, economy and scalability, and the materials are inexpensive. The overall method is simple to manufacture and easy to mass-produce. The above superhydrophobic and superoleophobic coating can not only be used to prevent water and oil from adhering to the metal surface and corroding the metal, but also can be used on various material substrates and is suitable for various environments. After testing, the water contact angle ≥ 150°, the contact angle of glycerol ≥ 146°, the contact angle of ethylene glycol ≥ 144°, the contact angle of soybean oil ≥ 141°. The coating can be reused, can be applied to various occasions to meet various needs, and its corrosion voltage can reach below -0.644V, lower than the -0.541V corrosion voltage of the Al alloy substrate; the corrosion current density can reach 2.353×10 -5 A·cm -2 below, lower than the 2.686×10 -5 A·cm -2 corrosion current density of the Al alloy substrate, especially being convenient for the anti-corrosion of metals in seawater.

[0120] The series of detailed descriptions listed above are only specific descriptions of the feasible embodiments of the present invention, and they are not intended to limit the protection scope of the present invention. Any equivalent embodiments or changes made without departing from the technical spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A superhydrophobic and superoleophobic coating with a columnar structure, characterized in that, It includes a substrate, on the surface of which there is an array composed of a number of columnar structures. The spacing between adjacent columnar structures is 120 - 400 μm, the height of the columnar structures is 150 - 500 μm, and the diameter of the columnar structures is 100 - 300 μm. Nano-ZnO needle-like structures are grown on the surface of the columnar structures to form a re-entrant structure, and the surface of the re-entrant structure is completely covered with a solidified SiO2 precursor solution. The volume ratio of the SiO2 precursor solution to the surface area of the re-entrant structure is (0.2 - 0.6) mL : 4 cm 2 , and the SiO2 precursor solution is obtained by modifying SiO2 particles with a low surface energy surfactant. The low surface energy surfactant is H,1H,2H,2H-perfluorodecyltriethoxysilane. The SiO2 precursor solution includes SiO2 nanoparticles, a low surface energy surfactant, absolute ethanol, ammonia water, and tetraethoxysilane. The mass ratio of SiO2 nanoparticles, absolute ethanol, ammonia water, tetraethoxysilane, and H,1H,2H,2H-perfluorodecyltriethoxysilane is: (2 - 2.5) : (12 - 15) : 100 : (2 - 2.5) : (1 - 1.25).

2. The superhydrophobic and superoleophobic coating with a columnar structure according to claim 1, characterized in that, The substrate is an Al alloy substrate.

3. A superhydrophobic and superoleophobic coating having a columnar structure according to claim 1, characterized in that, There is a three-proof paint layer between the surface of the re-entrant structure and the cured SiO2 precursor solution.

4. The superhydrophobic and superoleophobic coating with a columnar structure according to claim 1, wherein The SiO2 precursor solution is a fluorinated SiO2 nanoparticle suspension.

5. The preparation method of the superhydrophobic and superoleophobic coating with a columnar structure according to any one of claims 1 to 4, characterized in that, The method includes: Preparing an array composed of a plurality of columnar structures on the surface of the substrate by laser engraving; Growing nano-ZnO needle-like structures on the surface of the columnar structures by hydrothermal synthesis; Spraying the SiO2 precursor solution on the surface of the re-entrant structure and curing it to obtain a super-hydrophobic and oleophobic coating.

6. The preparation method of the superhydrophobic and superoleophobic coating with a columnar structure according to claim 5, characterized in that, The hydrothermal synthesis method includes: Taking isopropanol and zinc acetate, heating and mixing them evenly at 70-90 °C, adding triethylamine and fully reacting to obtain a ZnO seed solution. The mass ratio of isopropanol, zinc acetate to triethylamine is: (2-2.5):(2.5-3):100; Taking the ZnO seed solution and the substrate with columnar structures and reacting them at 85-95 °C for 1-2 h. After taking out the substrate and rinsing it, reacting it at 100-120 °C for 2-4 h to grow nano-ZnO needle-like structures on the surface of the columnar structures to form a re-entrant structure.

7. The preparation method of the superhydrophobic and superoleophobic coating with a columnar structure according to claim 5, characterized in that It includes spraying a three-proof paint solution on the surface of the re-entrant structure, heating and curing it to obtain a three-proof paint layer, and then spraying the SiO2 precursor solution on the surface of the three-proof paint layer and heating and curing it to obtain a super-hydrophobic and oleophobic coating.

8. Use of the super-omniphobic coating with a columnar structure according to any one of claims 1 to 4, characterized in that, The super-hydrophobic and oleophobic coating is arranged on the metal surface and is used to prevent water and oil from adhering to the metal surface and corroding the metal.

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