A flower-shaped micro-nano double-layer structure super-hydrophobic coating and its preparation method

Abstract

The invention discloses a kind of flower-like micro-nano double-layer structure super-hydrophobic coating and preparation method thereof, relate to material surface coating technical field.The preparation method of flower-like micro-nano double-layer structure super-hydrophobic coating of the present invention, comprise the following steps:Bonding powder is added in solvent and fully mixed, is sprayed onto substrate surface after mixing, after drying treatment, base layer is obtained;Described bonding powder is glass powder or thermoplastic powder;Polydimethylsiloxane and reduced iron powder are sequentially added in n-heptane solution, stir, and obtain modified mixed liquor;Modified mixed liquor is sequentially cleaned and dried, and reduced iron powder modifier is obtained;Reduced iron powder modifier is coated on base surface, is heat-treated, and super-hydrophobic top layer is formed at base surface, and flower-like micro-nano double-layer structure super-hydrophobic coating is obtained.The preparation method of the present invention can prepare and have excellent wear resistance, and the super-hydrophobic coating with strong substrate bonding force, solves the existing super-hydrophobic surface mechanical stability problem.

Description

Technical Field

[0001] The present invention relates to the technical field of material surface coatings, and in particular to a flower-shaped micro-nano double-layer structure super-hydrophobic coating and a preparation method thereof. Background Art

[0002] Many materials corrode in harsh operating environments, deteriorating their performance. Metals such as iron, copper, aluminum, and stainless steel are susceptible to chemical or electrochemical corrosion in harsh environments such as water, acid, alkali, and salt, which deteriorates their performance. Because corrosion is initiated at the interface between the aqueous medium and the material, modifying the interfacial effect of the material to impart superhydrophobicity can prevent corrosion, thereby extending the material's service life and expanding the application range of engineering metals.

[0003] Superhydrophobic surfaces originally originated from the surface of lotus leaves. Related research has shown that the lotus leaf surface has micro- and nano-scale structures. The synergistic interaction of surface micro- and nano-structures is the key factor in the superhydrophobic properties of the material surface. Therefore, the preparation of surface coatings with micro- and nano-rough structures is conducive to achieving surface superhydrophobicity. However, superhydrophobic surface coatings often suffer from poor mechanical stability, such as poor wear resistance and poor adhesion to the substrate, which poses great challenges to the practical application of superhydrophobic materials. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to propose a method for preparing a flower-shaped micro-nano double-layer structure super-hydrophobic coating, which can prepare a super-hydrophobic coating with excellent wear resistance and strong bonding with the substrate, solving the problem of poor mechanical stability of the existing super-hydrophobic surface.

[0005] Another object of the present invention is to provide a flower-shaped micro-nano double-layer structure super-hydrophobic coating, which is prepared by the above-mentioned preparation method. The super-hydrophobic coating of the present invention has excellent mechanical stability and super-hydrophobic properties.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] A method for preparing a flower-shaped micro-nano double-layer super-hydrophobic coating comprises the following steps:

[0008] (1) adding a bonding powder to a solvent and mixing thoroughly, spraying the mixed powder onto the surface of the substrate, and drying the mixed powder to obtain a base layer; the bonding powder is glass powder or thermoplastic powder;

[0009] (2) adding polydimethylsiloxane and reduced iron powder to the n-heptane solution in sequence and stirring evenly to obtain a modified mixed solution;

[0010] (3) washing and drying the modified mixed solution in sequence to obtain a modified reduced iron powder;

[0011] (4) The reduced iron powder modified substance is coated on the surface of the base layer and subjected to heat treatment to form a super-hydrophobic surface layer on the surface of the base layer, thereby obtaining a flower-like micro-nano double-layer structure super-hydrophobic coating.

[0012] Preferably, in step (2), the usage ratio of the polydimethylsiloxane, the reduced iron powder and the n-heptane solution is 1 g: (5-10 g): (10-30 ml).

[0013] Preferably, the operation method of step (2) is as follows: polydimethylsiloxane is added to the n-heptane solution, magnetically stirred for 5 to 10 minutes at a stirring speed of 300 to 600 rpm, and then reduced iron powder is added, magnetically stirred for 30 to 60 minutes at a stirring speed of 300 to 600 rpm to obtain a modified mixed solution.

[0014] Preferably, step (3) comprises the following steps:

[0015] Add n-heptane to the modified mixed solution and stir and clean it. The cleaning time is 5 to 10 minutes and the stirring speed is 300 to 600 rpm.

[0016] The modified mixed liquid after cleaning is dried at a temperature of 70 to 150° C. for 2 to 4 hours.

[0017] Preferably, in step (1), the thermoplastic powder is any one or more combinations of polyethylene terephthalate powder, polyphenylene sulfide powder, and polyetheretherketone powder (PEEK powder).

[0018] Preferably, in step (1), the mass ratio of the bonding powder to the volume ratio of the solvent is 1 g: (5-15 ml).

[0019] Preferably, in step (1), the bonding powder and the solvent are mixed as follows:

[0020] The mixture was stirred magnetically for 5 to 15 minutes at a stirring speed of 300 to 600 rpm, and then ultrasonically treated for 5 to 10 minutes.

[0021] Preferably, in step (1), the drying temperature is 100-150° C., and the drying time is 10-30 min;

[0022] In step (1), the solvent is ethanol.

[0023] Preferably, in step (4), the heat treatment temperature is 300-540° C., the holding time is 200-2000 min, and the heating rate is 5-15° C. / min.

[0024] Preferably, the thickness of the base layer is 10 to 50 μm.

[0025] A flower-shaped micro-nano double-layer super-hydrophobic coating is prepared by the above-mentioned preparation method of the flower-shaped micro-nano double-layer super-hydrophobic coating. The flower-shaped micro-nano double-layer super-hydrophobic coating comprises a base layer and a super-hydrophobic surface layer arranged in sequence from bottom to top.

[0026] The technical solutions provided by the embodiments of the present application may have the following beneficial effects:

[0027] 1. The flower-shaped micro-nano double-layer super-hydrophobic coating prepared by this technical solution is a modified super-hydrophobic material based on reduced iron powder. The air layer existing in the micro-nano structure of the super-hydrophobic surface can block the direct contact between water and the substrate. When the coating is placed underwater, a silver air layer appears on the surface. This air layer can effectively hinder the migration of ions to the coating surface, making the super-hydrophobic coating have excellent corrosion resistance, and the application of iron-based materials is further expanded.

[0028] 2. The super-hydrophobic coating of this technical solution has excellent mechanical stability. By using glass powder or thermoplastic powder as an intermediate layer between the adhesion substrate and the super-hydrophobic surface layer, this technical solution can not only solve the problem of weak bonding between the super-hydrophobic surface layer and the substrate, but also its excellent adhesion can enable the coating to be applied to a variety of substrate surfaces. In addition, the super-hydrophobic coating prepared by this technical solution also has excellent wear resistance, corrosion resistance and anti-fouling properties.

[0029] 3. The super-hydrophobic coating provided by this technology is non-toxic, environmentally friendly, and uses green solvents. The preparation process is simple, low-cost, and highly economical, making it suitable for large-scale industrial production. In terms of application, it can be applied to the surfaces of medical devices, automotive engines, car bodies, and other mechanical parts, as well as ships. It is particularly valuable in preventing corrosion and pollution of iron-based materials, extending the material's service life, reducing material consumption, and saving maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the contact angle of the super-hydrophobic coating prepared in Example 1 of the present invention;

[0031] Figure 2 This is a SEM top view of the super-hydrophobic coating prepared in Example 1 of the present invention;

[0032] Figure 3 This is a SEM cross-sectional image of the super-hydrophobic coating prepared in Example 1 of the present invention;

[0033] Figure 4 This is a cross-sectional local component test diagram of the super-hydrophobic coating prepared in Example 1 of the present invention;

[0034] Figure 5 The figure is a test result diagram of the salt spray test of the super-hydrophobic coating prepared in Example 1 of the present invention;

[0035] Figure 6 Graph showing the mechanical stability test results of the super-hydrophobic coating prepared in Example 1 of the present invention;

[0036] Figure 7 Schematic diagram of the antifouling performance testing process of the super-hydrophobic coating prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0037] For ease of understanding of the present invention, the present invention will be described more fully below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0038] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in this field or the product instructions were used. Raw materials used without manufacturer specified are all commercially available conventional products.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0040] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0041] A method for preparing a flower-shaped micro-nano double-layer super-hydrophobic coating comprises the following steps:

[0042] (1) adding a bonding powder to a solvent and mixing thoroughly, spraying the mixed powder onto the surface of the substrate, and drying the mixed powder to obtain a base layer; the bonding powder is glass powder or thermoplastic powder;

[0043] (2) adding polydimethylsiloxane (PDMS) and reduced iron powder to the n-heptane solution in sequence and stirring evenly to obtain a modified mixed solution;

[0044] (3) washing and drying the modified mixed solution in sequence to obtain a modified reduced iron powder;

[0045] (4) The reduced iron powder modified substance is coated on the surface of the base layer and subjected to heat treatment to form a super-hydrophobic surface layer on the surface of the base layer, thereby obtaining a flower-like micro-nano double-layer structure super-hydrophobic coating.

[0046] It is worth noting that the super-hydrophobic coating prepared by this technical solution is a modified super-hydrophobic material based on iron. The air layer present in the super-hydrophobic surface micro-nanostructure can block the direct contact between water and metallic iron. When the coating is placed underwater, a silver air layer appears on the surface. This air layer can effectively hinder the migration of ions to the coating surface, making the super-hydrophobic iron-based material have excellent corrosion resistance, and the application of iron-based materials is further expanded.

[0047] The preparation method of this technical solution first builds one deck of base at substrate surface, then the reduced iron powder (i.e. modifier) ​​modified by PDMS is coated on base surface, finally coating is heat-treated, obtains flower-like micro-nano double-layer structure super-hydrophobic coating.The principle realizing coating super-hydrophobicity and corrosion resistance in this technical solution is mainly for constructing micro-nano structure on surface, reduced iron powder is under high-temperature heating effect, mutual diffusion bonding agglomeration between the reduced iron powder contacting each other, constitutes dense and irregularly shaped micron agglomerates, with obvious micron-level rough structure, these micron agglomerates are further observed, there is a dense nano-flaky and needle-like oxide on its surface, the mutual coordination of micron structure and nanostructure provides many air bags to coating surface, these air bags hinder water from contacting with coating solid surface, when water droplets fall on coating surface, water droplets are almost suspended in coating surface, effectively reduce corrosion ions while realizing coating super-hydrophobicity and migrate to coating surface by aqueous medium, so that coating surface has anti-corrosive performance.

[0048] The flower-like micro-nano double-layer structure super-hydrophobic coating prepared by this technical solution also has excellent mechanical stability, not only has stronger bonding force with substrate, coating surface also has good wear resistance. The super-hydrophobic coating of this technical solution makes glass powder or thermoplastic powder heat and melt in preparation process, utilizes material to bond substrate and modifier in molten state. Now, glass powder or thermoplastic powder are as the intermediate layer of substrate and modifier, on the one hand, coating can be made to be firmly bonded to substrate, on the other hand, it is also possible to make glass powder or thermoplastic powder and modifier carry out wrapping or half-wrapped physical bonding, strengthen the close combination between modified particles.

[0049] It's important to note that reduced iron powder, also known as "double absorbent," is a gray or black powder primarily composed of elemental iron. It's typically produced by reducing ferroferric oxide (Fe3O4) in a stream of hydrogen or carbon monoxide under high heat. Reduced iron powder is a powder with a very loose microstructure and a large surface area.

[0050] Preferably, the particle size of the reduced iron powder selected in this technical solution is 80-200 mesh.

[0051] Specifically, before spraying the base layer in step (1), impurities on the surface of the substrate are first removed to enhance the bonding force between the bonding powder and the substrate, thereby increasing the adhesion of the entire super-hydrophobic coating to the substrate.

[0052] Specifically, the substrate is made of a metal material or an inorganic non-metallic material.

[0053] Preferably, in step (4), the method of coating the modified substance on the surface of the base layer includes any one of sieving, spraying and sprinkling. Among them, the sieving method is to place the base layer on a horizontal surface, and use a sieve to cover the surface of the base layer with a layer of modified substance, and the sieve used can be a particle size of 200-800 mesh; the spraying or sprinkling method is to add the modified substance to an ethanol solution, use a stirrer to fully mix, and then spray or sprinkling. Preferably, the ratio of the modified substance to the ethanol solution is 3g: (5-10ml), which can coat the modified substance on the surface of the base layer and facilitate subsequent heat treatment.

[0054] Further explanation, in step (2), the usage ratio of the polydimethylsiloxane, the reduced iron powder and the n-heptane solution is 1g: (5-10g): (10-30ml). Within this ratio range, the PDMS-wrapped modified reduced iron powder can be obtained.

[0055] Further explanation, the operation method of step (2) is as follows: polydimethylsiloxane (PDMS) is added to the n-heptane solution, magnetically stirred for 5 to 10 minutes at a stirring speed of 300 to 600 rpm, and then reduced iron powder is added, magnetically stirred for 30 to 60 minutes at a stirring speed of 300 to 600 rpm to obtain a modified mixed solution.

[0056] The technical solution adds polydimethylsiloxane (PDMS) to an n-heptane solution, and magnetically stirs it for 5 to 10 minutes at a stirring speed of 300 to 600 rpm to fully dissolve it in the n-heptane solution; then, reduced iron powder is added, and magnetically stirred for 30 to 60 minutes at a stirring speed of 400 to 600 rpm to obtain a modified mixed solution. The reduced iron powder is modified by using the PDMS in the solution, thereby reducing the solid surface energy of the reduced iron powder.

[0057] To further illustrate, step (3) includes the following steps:

[0058] To wash away excess PDMS, n-heptane (10-20 ml) was added to the modified mixture and stirred for 5-10 min at a stirring speed of 300-600 rpm.

[0059] The modified mixed liquid after cleaning is dried at a temperature of 70 to 150° C. for 2 to 4 hours.

[0060] Further explanation, in step (1), the thermoplastic powder is any one or more combinations of polyethylene terephthalate powder (PET powder), polyphenylene sulfide powder (PPS powder), and polyetheretherketone powder (PEEK powder).

[0061] Further explanation, in step (1), the mass ratio of the bonding powder to the volume ratio of the solvent is 1g:(5-15ml). Within this ratio, a better spraying effect can be obtained and it is convenient to dry and remove the solvent later. Exemplary mass ratios of the bonding powder to the volume ratio of the solvent are 1g:5ml, 1g:6ml, 1g:7ml, 1g:8ml, 1g:9ml, 1g:10ml, 1g:11ml, 1g:12ml, 1g:13ml, 1g:14ml, 1g:15ml, but are not limited thereto.

[0062] To further illustrate, in step (1), the method of mixing the bonding powder and the solvent is as follows:

[0063] The bonding powder is fully mixed in the solvent by magnetic stirring for 5 to 15 minutes at a stirring speed of 300 to 600 rpm, and then ultrasonic treatment is performed for 5 to 10 minutes.

[0064] Further explanation, in step (1), the drying temperature is 100-150°C and the drying time is 10-30 minutes;

[0065] In step (1), the solvent is ethanol.

[0066] It is worth noting that the drying method of step (1) is as follows: the sample is placed in an oven for drying at a temperature of 100-150°C for 10-30 minutes. After drying, a base layer is obtained on the surface of the substrate, which is used as an adhesive.

[0067] Further explanation: in step (4), the heat treatment temperature is 300-540°C, the holding time is 200-2000 min, and the heating rate is 5-15°C / min.

[0068] It is worth noting that the heat treatment method of the present technical solution is as follows: the substrate coated with the modifier is placed in a heat treatment furnace, and the heat treatment is carried out at a temperature of 300-540°C for 200-2000min, with a heating rate of 5-15°C / min, and the temperature is taken out when it drops to room temperature. The heat treatment temperature of the present technical solution should be higher than the melting point temperature of the base layer to ensure that the base layer can be melted during the heat treatment process so that the base layer can give full play to the effect of bonding, thereby improving the mechanical stability of the super-hydrophobic coating. Therefore, in order to ensure that the base layer can be completely melted, the heat treatment temperature should be higher than the melting point temperature of the base layer by more than 20°C.

[0069] Further description, the thickness of the base layer is 10 to 50 μm.

[0070] It is worth noting that the thickness control of present technical program base layer is between 10~50 μm, can not only promote the bonding force between super-hydrophobic top layer and substrate, and can promote the super-hydrophobic performance of flower-like micro-nano double-layer structure super-hydrophobic coating, if coating thickness is too thin (<10 μm), base layer cohesion can be caused to decline, the bonding powder of base layer is difficult to wrap up modifier, when coating is too thick (>50 μm), the bonding powder of base layer is too much, causes to wrap up modifier transition, the modifier of heating and melting rear surface is covered by base layer, is unfavorable for forming super-hydrophobic surface structure.Present technical program specifically can control base layer thickness by controlling the consumption of spraying solution.

[0071] A flower-shaped micro-nano double-layer super-hydrophobic coating is prepared by the above-mentioned preparation method of the flower-shaped micro-nano double-layer super-hydrophobic coating. The flower-shaped micro-nano double-layer super-hydrophobic coating comprises a base layer and a super-hydrophobic surface layer arranged in sequence from bottom to top.

[0072] It is worth noting that the flower-shaped micro-nano double-layer structure super-hydrophobic coating of this technical solution is an iron-based super-hydrophobic coating with a micro-nano structure. It has excellent corrosion resistance, mechanical stability and anti-fouling properties. It can be used in offshore platforms, underwater detectors, medical equipment and ships, etc., and further expands the application of iron-based materials, especially in the corrosion and pollution prevention of iron-based materials, extending the service life of the material, reducing losses, reducing maintenance costs, and having good economic benefits.

[0073] The technical solution of the present invention is further described below with reference to specific embodiments.

[0074] Example 1

[0075] The method for preparing the flower-shaped micro-nano double-layer super-hydrophobic coating of this embodiment comprises the following steps:

[0076] (1) Preparation of a base layer: Before preparation, a glass substrate is placed in ethanol, acetone, and deionized water solutions in sequence for ultrasonic cleaning and drying; 2 g of glass powder is added to 10 ml of ethanol solution, stirred with a magnetic stirrer for 10 min, and then ultrasonically treated in an ultrasonic cleaner for 10 min to fully mix, wherein the stirring speed is 600 rpm. After fully mixing, the solution is sprayed onto the surface of the glass substrate using a spray gun and dried at a drying temperature of 120°C for 10 min. After drying, a uniform glass powder base layer is obtained on the surface of the glass substrate;

[0077] (2) 1 g of PDMS was added to 10 ml of n-heptane solution and stirred for 10 min using a stirrer at a stirring speed of 400 rpm. After the PDMS was fully dissolved in n-heptane, 5 g of reduced iron powder was added and the mixture was stirred at a stirring speed of 400 rpm for 30 min to obtain a modified mixed solution.

[0078] (3) The modified mixed solution of step (2) was added to 20 ml of n-heptane solution for stirring and washing at a stirring speed of 600 rpm for 10 min. To remove the solvent, the washed solution was placed in an oven and dried at a temperature of 70° C. for 4 h to obtain a PDMS-modified reduced iron powder;

[0079] (4) 6 g of the modified reduced iron powder of step (3) was uniformly mixed in 10 ml of ethanol solution and sprayed on the surface of the base layer in step (1). The coating was placed in a 540°C heat treatment furnace and kept warm for 200 min at a heating rate of 10°C / min. After the holding time was over, it was taken out after cooling to room temperature to form a super-hydrophobic surface layer on the surface of the base layer, thereby obtaining a flower-shaped micro-nano double-layer structure super-hydrophobic coating.

[0080] Example 2

[0081] The method for preparing the flower-shaped micro-nano double-layer super-hydrophobic coating of this embodiment comprises the following steps:

[0082] (1) Preparation of the base layer: Before preparation, the copper sheet (i.e., the polar region) was placed in ethanol, acetone, and deionized water solutions for ultrasonic cleaning and drying. 1 g of polyethylene terephthalate powder (PET powder) was added to 10 ml of ethanol solution, stirred with a magnetic stirrer for 10 min, and then ultrasonically treated in an ultrasonic cleaner for 5 min to fully mix. The stirring speed was 500 rpm. After fully mixing, the solution was sprayed onto the surface of the copper sheet substrate using a spray gun and dried at a drying temperature of 100°C for 30 min. After drying, a uniform PET powder base layer was obtained on the surface of the copper sheet.

[0083] (2) 1 g of PDMS was added to 19 ml of n-heptane solution and stirred for 10 min using a stirrer at a stirring speed of 400 rpm. After the PDMS was fully dissolved in the n-heptane, 7.5 g of reduced iron powder was added and the mixture was stirred at a stirring speed of 400 rpm for 50 min to obtain a modified mixed solution.

[0084] (3) The modified mixed solution of step (2) was added to 15 ml of n-heptane solution for stirring and washing at a stirring speed of 600 rpm for 10 min. To remove the solvent, the washed solution was placed in an oven and dried at a temperature of 80° C. for 2 h to obtain a PDMS-modified reduced iron powder;

[0085] (4) 6 g of the reduced iron modification of step (3) was uniformly mixed in 16 ml of ethanol solution and drop-coated on the surface of the base layer in step (1). The coating was placed in a 300 ° C heat treatment furnace and kept warm for 1440 min at a heating rate of 10 ° C / min. After the insulation time was over, it was taken out after cooling to room temperature to obtain a flower-shaped micro-nano double-layer structure super-hydrophobic coating.

[0086] Example 3

[0087] The method for preparing the flower-shaped micro-nano double-layer super-hydrophobic coating of this embodiment comprises the following steps:

[0088] (1) Preparation of the base layer: Before preparation, the aluminum sheet substrate was placed in ethanol, acetone, and deionized water solutions in sequence for ultrasonic cleaning and drying; 1 g of polyphenylene sulfide powder (PPS powder) was added to 15 ml of ethanol solution, stirred with a magnetic stirrer for 10 min, and then ultrasonically treated in an ultrasonic cleaner for 5 min to fully mix, wherein the stirring speed was 400 rpm. After fully mixing, the solution was sprayed onto the surface of the aluminum sheet substrate using a spray gun and dried at a drying temperature of 140°C for 10 min. After drying, a uniform PPS powder base layer was obtained on the surface of the aluminum sheet;

[0089] (2) 1 g of PDMS was added to 29 ml of n-heptane solution and stirred for 10 min using a stirrer at a stirring speed of 600 rpm. After the PDMS was fully dissolved in the n-heptane, 10 g of reduced iron powder was added and the mixture was stirred at a stirring speed of 600 rpm for 60 min to obtain a modified mixed solution.

[0090] (3) The modified mixed solution of step (2) was added to 10 ml of n-heptane solution for stirring and washing at a stirring speed of 600 rpm for 10 min. To remove the solvent, the washed solution was placed in an oven and dried at a temperature of 100° C. for 3 h to obtain a PDMS-modified reduced iron powder;

[0091] (4) 3 g of the modified reduced iron powder in step (3) was uniformly mixed in 10 ml of ethanol solution and sprayed on the surface of the base layer in step (1). The coating was placed in a 320°C heat treatment furnace and kept warm for 1440 min at a heating rate of 10°C / min. After the holding time was over, it was cooled to room temperature and then taken out to obtain a flower-shaped micro-nano double-layer structure super-hydrophobic coating.

[0092] Example 4

[0093] The method for preparing the flower-shaped micro-nano double-layer super-hydrophobic coating of this embodiment comprises the following steps:

[0094] (1) Preparation of the base layer: Before preparation, the stainless steel sheet substrate was placed in ethanol, acetone, and deionized water solution in sequence for ultrasonic cleaning and drying; 2 g of polyetheretherketone powder (PEEK powder) was added to 15 ml of ethanol solution, stirred with a magnetic stirrer for 10 min, and then ultrasonically treated in an ultrasonic cleaner for 10 min to fully mix, wherein the stirring speed was 500 rpm. After fully mixing, the solution was sprayed onto the surface of the stainless steel substrate using a spray gun and dried at a drying temperature of 120°C for 10 min. After drying, a uniform PEEK powder base layer was obtained;

[0095] (2) 2 g of PDMS was added to 25 ml of n-heptane solution and stirred for 10 min using a stirrer at a stirring speed of 600 rpm. After the PDMS was fully dissolved in the n-heptane, 7 g of reduced iron powder was added and the mixture was stirred at a stirring speed of 600 rpm for 60 min to obtain a modified mixed solution.

[0096] (3) The modified mixed solution of step (2) was added to 20 ml of n-heptane solution for stirring and washing at a stirring speed of 600 rpm for 10 min. To remove the solvent, the washed solution was placed in an oven and dried at a temperature of 100° C. for 4 h to obtain a PDMS-modified reduced iron powder;

[0097] (4) The reduced iron powder modified product of step (3) is evenly covered on the surface of the base layer in step (1) using a 200-mesh screen, and the coating is then placed in a 360°C heat treatment furnace for 2000 minutes at a heating rate of 10°C / min. After the insulation time is over, it is taken out after cooling to room temperature to obtain a flower-shaped micro-nano double-layer structure super-hydrophobic coating.

[0098] Specifically, the surface water contact angle, SEM top view, SEM cross-sectional view and component test of the flower-shaped micro-nano double-layer structure super-hydrophobic coating prepared in Example 1 were tested, and the test results were as follows: Figure 1-4 As shown, the super hydrophobic coating prepared in Example 1 was subjected to corrosion resistance test, mechanical stability test and antifouling performance test, and the test results are shown in FIG. Figure 5-7 shown.

[0099] Figure 1 This is a schematic diagram of the contact angle profile of the surface of the flower-shaped micro-nano double-layer structure superhydrophobic coating (hereinafter referred to as the superhydrophobic coating) prepared in Example 1. It can be seen that the water contact angle on the surface of the superhydrophobic coating can reach 158°, the coating surface has a high contact angle, and the coating surface has superhydrophobic properties.

[0100] Figure 2 and Figure 3 The SEM top view and SEM cross-sectional view of the surface of the super-hydrophobic coating prepared in Example 1 are respectively. Figure 2 It can be seen from a that the surface of the super-hydrophobic coating is composed of irregularly shaped micron clusters and has obvious micron-level rough structures. These rough structures are reduced iron powder (particle size 200 mesh) after heat treatment. Under the effect of high temperature heating, the reduced iron powders in contact with each other diffuse and bond together. The micron clusters on its surface are magnified and analyzed. Figure 2 In b, it can be clearly seen that there are a large number of nano-sheet and filamentous oxides on the surface of the micron cluster. These nano-scale oxides are densely distributed on the surface of the micron-sized reduced iron powder particles and construct a micro-nano-scale hierarchical structure on the surface of the super-hydrophobic coating. Figure 3 The cross-sectional structure of the super-hydrophobic coating can be seen. The middle bonding layer (dashed line area) constructed by glass powder is clearly visible in the figure. The glass powder after high temperature heat treatment is mixed with the substrate and micron-sized reduced iron powder without obvious boundary layer. Figure 3 The white box area) is subjected to element scanning analysis, and the results are as follows Figure 4 As shown, the main elements in the glass frit interlayer are O, Na, Si, K, and Ca (from the glass frit), with a small amount of Fe (6.49% from the reduced iron powder). Elemental analysis indicates that the glass frit interlayer (i.e., the base layer) and the reduced iron powder on the coating surface undergo effective interdiffusion bonding during high-temperature heat treatment. The presence of the glass frit interlayer effectively improves the poor compatibility between the reduced iron powder and the substrate surface, enhancing the mechanical stability of the coating surface.

[0101] Figure 5 The test results of the salt spray test of the super hydrophobic coating prepared in Example 1 of the present invention are shown. The neutral salt spray test is used to simulate the corrosive environment of marine applications. The salt spray test is carried out for 3 days at a temperature of 35°C and a concentration of 5wt% NaCl, and the contact angle of the coating surface is measured every other day. Figure 5 It can be seen that the contact angle of the coating is still greater than 150° after 24 hours of salt spray test, the contact angle is lower than 150° after 48 hours, and the contact angle is lower than about 90° after 72 hours, indicating that the superhydrophobic coating has excellent corrosion resistance.

[0102] Figure 6 Super-hydrophobic coating mechanical stability test result obtained for Example 1. Wear test is carried out using a sample having a size of 2.5cm × 4.0cm. During testing, the sample is inverted on a silicon carbide sandpaper (400#) surface, and under a load of 100g, the coating surface is scratched with sandpaper in a fixed direction at a speed of 1cm / s, with 20 centimeters of movement as a cycle, and the change of a surface WCA value is recorded after each cycle. As can be seen from the figure, the coating has gone through 8 cycles and the contact angle is only less than 150 °, and the angle is greater than 140 °, and there is still a higher contact angle, which embodies the excellent mechanical stability of the coating.

[0103] Figure 7 The antifouling performance test diagram of the super hydrophobic coating surface prepared in Example 1 is shown. The super hydrophobic coating surface is tilted at a certain angle, a certain amount of sand is evenly sprinkled on the end of the sample, and droplets are sucked with a needle to perform the antifouling performance test. Figure 7 As can be seen in the image above, the droplet, after free-falling, quickly rolls off the surface of the superhydrophobic sample, carrying away any sand along the way. It takes less than 1ml of water to completely remove all the sand from the superhydrophobic sample, indicating that the adhesion between the sand and the superhydrophobic coating is very low. The rolling water droplet easily removes contaminants, resulting in the coating exhibiting excellent antifouling properties and potential applications in the antifouling field.

[0104] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are intended solely to illustrate the principles of the present invention and are not to be construed in any way as limiting the scope of protection of the present invention. Based on the explanations herein, those skilled in the art will readily conceive of other specific embodiments of the present invention without inventive effort, and such embodiments will fall within the scope of protection of the present invention.

Claims

1. A method for preparing a flower-shaped micro-nano double-layer structure super-hydrophobic coating, characterized in that: The following steps are involved: (1) Adding a bonding powder to a solvent and fully mixing the mixture, spraying the mixture onto the surface of a substrate, and drying the mixture to obtain a base layer, wherein the thickness of the base layer is 10 to 50 μm; the mass ratio of the bonding powder to the volume of the solvent is 1 g: (5 to 15 ml); the bonding powder is glass powder or thermoplastic powder, and the thermoplastic powder is any one or more of polyethylene terephthalate powder, polyphenylene sulfide powder, and polyetheretherketone powder; (2) adding polydimethylsiloxane and reduced iron powder to the n-heptane solution in sequence and stirring evenly to obtain a modified mixed solution; the amount ratio of the polydimethylsiloxane, the reduced iron powder and the n-heptane solution is 1g: (5-10g): (10-30ml); (3) washing and drying the modified mixed liquid in sequence to obtain a modified reduced iron powder; (4) The reduced iron powder modified substance is coated on the surface of the base layer and subjected to heat treatment to form a super hydrophobic surface layer on the surface of the base layer, thereby obtaining a flower-like micro-nano double-layer super hydrophobic coating; wherein the heat treatment temperature is 300~540℃, the holding time is 200~2000min, and the heating rate is 5~15℃ / min.

2. The method for preparing a flower-shaped micro-nano double-layer structure super-hydrophobic coating according to claim 1, wherein The operation method of step (2) is as follows: add polydimethylsiloxane to the n-heptane solution, stir magnetically for 5 to 10 minutes at a stirring speed of 300 to 600 rmp / min, then add reduced iron powder, stir magnetically for 30 to 60 minutes at a stirring speed of 300 to 600 rmp / min, and obtain a modified mixed solution.

3. The method for preparing a flower-shaped micro-nano double-layer structure super-hydrophobic coating according to claim 1, wherein Step (3) includes the following steps: Add n-heptane to the modified mixed solution and stir and clean it. The cleaning time is 5-10 minutes and the stirring speed is 300-600 rpm. The modified mixed liquid after cleaning is dried at a drying temperature of 70-150°C and a drying time of 2-4 hours.

4. The method for preparing a flower-shaped micro-nano double-layer structure super-hydrophobic coating according to claim 1, wherein In step (1), the drying temperature is 100-150°C and the drying time is 10-30 minutes; In step (1), the solvent is ethanol.

5. A flower-shaped micro-nano double-layer structure super-hydrophobic coating, characterized in that: The flower-shaped micro-nano double-layer structure super-hydrophobic coating is prepared by the preparation method of any one of claims 1 to 4, wherein the flower-shaped micro-nano double-layer structure super-hydrophobic coating comprises a base layer and a super-hydrophobic surface layer arranged sequentially from bottom to top.

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