Photo-thermal super-hydrophobic coating and preparation method thereof

Abstract

The invention relates to a photo-thermal super-hydrophobic coating and a preparation method thereof, and belongs to the technical field of super-hydrophobic coatings. A coating material adopted by the coating comprises the following components in parts by weight: 1 part of nano carbon black, 44 to 5 parts of nano Fe3O4, 2 to 4 parts of 1H, 1H, 2H, 2H-perfluorodecyl trimethoxysilane, 47 to 64 parts of absolute ethyl alcohol, 6 to 8 parts of epoxy resin, 1 to 2 parts of an epoxy resin curing agent and 9 to 18 parts of ethyl acetate; the particle size of the nano carbon black is 15 nm to 25 nm, and the particle size of the nano Fe3O4 is 160 nm to 240 nm; the coating is excellent in super-hydrophobic performance and good in photo-thermal performance and icing resistance, can well protect a base body in a severe environment, and is particularly suitable for being used as a surface coating of a fan blade used in the severe environment. According to the method, the coating material is prepared into suspension liquid, the suspension liquid is sprayed on the base body, the coating surface is uniform, the method is suitable for any base body in any shape, the process is simple, and operation is easy and convenient.

Description

Technical Field

[0001] The present invention relates to a photothermal superhydrophobic coating and a preparation method thereof, belonging to the technical field of superhydrophobic coatings. Background Art

[0002] Ice formation, as a common phenomenon in nature, poses non-negligible negative effects and challenges to multiple key industries such as aviation, power supply, transportation, and shipping.

[0003] The wettability of a solid surface is usually determined by its surface chemical composition and microstructure. Due to its unique non-wettability, that is, the contact angle between a water droplet and the solid surface > 150° and the rolling angle < 10°, superhydrophobic surfaces have extremely important application prospects in fields such as industrial production and daily life. Inspired by the "lotus effect", the key to preparing superhydrophobic surfaces is to combine low-surface-energy substances with micro-nano hierarchical structures to construct a micro-nano composite structure that mimics the lotus leaf surface. Compared with single micro or nano structures, the micro-nano secondary hierarchical structure can effectively intercept more air, form a stable air layer between the solid surface and the liquid droplet, greatly reduce the solid-liquid contact area, and enable the surface to achieve a larger contact angle and a smaller rolling angle. This feature makes superhydrophobic coatings with micro-nano structured superhydrophobic surfaces widely accepted and regarded as an effective anti-icing countermeasure.

[0004] In order to endow superhydrophobic coatings with more efficient anti-icing performance, people have incorporated photothermal materials into superhydrophobic coating materials to prepare photothermal superhydrophobic coatings. Since photothermal materials have the ability to efficiently convert clean and sustainable solar energy into heat energy, photothermal superhydrophobic coatings can utilize the principle of photothermal reaction, that is, absorb solar energy and convert it into heat energy, thereby effectively melting and removing the ice layer covering the material surface, achieving environmentally friendly and efficient de-icing, and at the same time having the characteristics of convenient production and low cost. Therefore, photothermal superhydrophobic coatings play an important role in the field of anti-icing and de-icing.

[0005] Chinese patent application with publication number CN117447917A discloses a wear-resistant micro-nano structured superhydrophobic coating with a photothermal effect and a preparation method thereof. The method includes the following steps: spin-coating a defoamed PDMS prepolymer and curing agent mixture onto a substrate and performing pre-curing treatment; adding micron carbon black particles or nano carbon black particles with a photothermal effect into an organic solvent respectively and performing ultrasonic dispersion to obtain a dispersion; spraying the micron carbon black dispersion onto the surface of the substrate coated with PDMS, and then spraying the nano carbon black dispersion to obtain a coating with a micro-nano structure and a photothermal effect; then spraying a layer of PDMS prepolymer and curing agent mixture diluted with an organic solvent on the surface and performing low-temperature curing to obtain a superhydrophobic film. This method has a complex preparation process, a high cost, and a poor photothermal effect, which is insufficient to meet the current usage requirements. Summary of the Invention

[0006] To overcome the defects of the existing technology, one of the purposes of the present invention is to provide a photothermal superhydrophobic coating; the coating has excellent superhydrophobic performance, good photothermal performance and anti-icing performance, and can better protect the substrate in harsh environments, especially suitable for use as the surface coating of fan blades used in harsh environments.

[0007] Another purpose of the present invention is to provide a preparation method of the photothermal superhydrophobic coating.

[0008] To achieve the purpose of the present invention, the following technical solutions are provided.

[0009] A photothermal superhydrophobic coating, in the coating material used for the coating, the components and their weight parts are as follows:

[0010]

[0011] Among them, the particle size of nano-carbon black is 15nm - 25nm, and the particle size of nano-Fe3O4 is 160nm - 240nm;

[0012] The coating material is prepared into a suspension and sprayed on the substrate to prepare a photothermal superhydrophobic coating.

[0013] Preferably, the thickness of the coating is 90μm - 130μm.

[0014] The substrate of the superhydrophobic coating is fiberglass, preferably a fan blade made of fiberglass.

[0015] A preparation method of the photothermal superhydrophobic coating of the present invention, the steps of the method are as follows:

[0016] (1) Nano-carbon black and nano-Fe3O4 are successively added to absolute ethanol and ultrasonically dispersed evenly, and then 1H,1H,2H,2H-perfluorodecyltrimethoxysilane is added and further ultrasonically dispersed evenly to obtain a modified nano-particle dispersion;

[0017] Preferably, nano-carbon black and nano-Fe3O4 are successively added to absolute ethanol and ultrasonically dispersed, the ultrasonic time is 20min - 30min, and the ultrasonic power is 150W - 180W;

[0018] Preferably, when adding 1H,1H,2H,2H-perfluorodecyltrimethoxysilane for further ultrasonic dispersion, the ultrasonic time is 20min - 30min, and the ultrasonic power is 150W - 180W;

[0019] (2) Epoxy resin and curing agent are added to ethyl acetate and stirred evenly to obtain an epoxy resin solution;

[0020] Preferably, the epoxy resin is E-51 epoxy resin with a molecular weight of 600;

[0021] Preferably, the curing agent is T-31 epoxy resin curing agent with an amine value of 460 mg KOH / g to 550 mg KOH / g;

[0022] Preferably, the epoxy resin and the curing agent are added into ethyl acetate and stirred at 50°C to 60°C for 1 h to 2 h until evenly mixed.

[0023] (3) Add the epoxy resin solution to the modified nanoparticle dispersion and mix, and disperse evenly by ultrasonic wave to prepare a suspension of nanoparticles and low surface energy mixture, which is the coating material suspension;

[0024] Preferably, when adding the epoxy resin solution to the modified nanoparticle dispersion and mixing, the ultrasonic time for ultrasonic dispersion is 1 h to 2 h, and the ultrasonic power is 150 W to 180 W.

[0025] (4) Spray the coating material suspension on a clean substrate, dry it, and prepare a photothermal superhydrophobic coating;

[0026] Air spraying is preferably used, specifically:

[0027] Vertically spray the coating material suspension onto the clean substrate with a spray gun, the spraying distance is 10 cm to 15 cm, and the air pressure is 0.2 MPa to 0.3 MPa.

[0028] The clean substrate can be obtained by conventional technical means in the art. For example, ultrasonic cleaning is used to clean the surface of the substrate to remove impurities such as dust and oil adhered to the surface of the substrate.

[0029] Preferably, dry at 80°C to 100°C for 30 min to 40 min.

[0030] Beneficial effects

[0031] (1) The present invention provides a photothermal superhydrophobic coating. The water contact angles of the coating are all greater than 150°, and the sliding angles are all less than 10°. It has excellent hydrophobicity, and excellent photothermal performance and anti-icing performance. It can be well applied to harsh environments, especially on the fan blades used in harsh environments for anti-icing and de-icing.

[0032] (2) The present invention provides a photothermal superhydrophobic coating. In this coating, smaller-sized particles (nano carbon black) and larger-sized particles (nano Fe3O4) are combined. The smaller-sized particles can be relatively distributed in the gaps between the larger-sized particles, thus effectively reducing the large agglomeration of the particles. Since the larger-sized nano Fe3O4 has a hard texture, its mechanical strength is significantly improved after uniform distribution; the smaller-sized nano carbon black is distributed in the gaps of the larger-sized nano Fe3O4, constructing a micro-nano structure and forming a suitable roughness. After optimizing the dosage ratio of nano carbon black and nano Fe3O4, the particles of the two sizes are evenly distributed in the microstructure, overlapping and interlocking with each other, having an obvious sense of hierarchy, forming a honeycomb-like micro-nano structure. A large number of air cavities are stored in the "honeycomb" holes to hold up water droplets, thus achieving the superhydrophobic effect. Moreover, due to the high specific surface area of the double-sized nanoparticles and the uniformly layered micro-nano structure, and its layered structure, as well as the fact that both nano carbon black and nano Fe3O4 have a photothermal effect, light can be captured by the coating through multiple reflections inside the coating and effectively converted into heat, so it has a good anti-icing and de-icing effect.

[0033] (3) The present invention provides a photothermal superhydrophobic coating. In this coating, the dosages of nanoparticles and epoxy resin are limited. Different from the common view in the prior art that when the dosage of the binder epoxy resin is large, its wear resistance and corrosion resistance are good, the present invention finds based on a large number of experiments that if the binder epoxy resin is used in excess, the superhydrophobic film will lose its superhydrophobicity, indicating that the mass ratio of nanoparticles to epoxy resin is crucial and not the more the better. The reason is that too much epoxy resin will completely wrap the nanoparticles, resulting in the loss of their hydrophobicity.

[0034] (4) The present invention provides a photothermal superhydrophobic coating. In this coating, the dosages of nanoparticles and the hydrophobic modifier 1H,1H,2H,2H-perfluorodecyltrimethoxysilane are limited. Different from the common view in the prior art that when the dosage of the hydrophobic modifier 1H,1H,2H,2H-perfluorodecyltrimethoxysilane is large, its hydrophobic performance is good, the present invention finds based on a large number of experiments that if the hydrophobic modifier 1H,1H,2H,2H-perfluorodecyltrimethoxysilane is used in excess, the superhydrophobic film will lose its superhydrophobicity, indicating that the mass ratio of nanoparticles to the hydrophobic modifier 1H,1H,2H,2H-perfluorodecyltrimethoxysilane is crucial and not the more the better. The reason is that too much 1H,1H,2H,2H-perfluorodecyltrimethoxysilane will fill the surface microstructures, reducing its roughness and thus leading to a decrease in its hydrophobicity.

[0035] (5) The present invention provides a photothermal superhydrophobic coating with a thickness of 90 μm to 130 μm, which will not cause an increase in internal stress due to excessive thickness, thus avoiding cracking and peeling of the coating.

[0036] (6) The present invention provides a method for preparing a photothermal superhydrophobic coating. The method involves preparing a suspension of the coating material and obtaining the coating by spraying it onto a substrate. The surface of the coating is uniform and applicable to any substrate of any shape. The process is simple and easy to operate.

[0037] (7) The present invention provides a method for preparing a photothermal superhydrophobic coating. In the preparation method, nano-carbon black particles with smaller particle sizes are first added to a solvent, and then nano-Fe3O4 with larger particle sizes is added to the solvent. This can enable the smaller particle-sized particles to be better distributed in the gaps between the larger particle-sized particles, resulting in a better hydrophobic effect.

[0038] (8) The present invention provides a method for preparing a photothermal superhydrophobic coating. In the preparation method, air spraying is preferably used. The suspension is vertically sprayed onto a clean substrate with a spray gun at a spraying distance of 10 cm to 15 cm. If the distance is too close, it will lead to poor atomization effect, uneven coating, too thick coating film and sagging phenomenon; if the distance is too far, part of the coating slurry will volatilize on the way to the substrate surface, resulting in too thin coating film, uneven coating, poor covering power and decreased adhesion; the air pressure is 0.2 MPa to 0.3 MPa. Appropriate spraying air pressure can not only make the coating atomize more finely, thus obtaining a more uniform coating surface, but also improve the adhesion between the coating and the substrate; if the air pressure is too high, the speed of the coating droplets is too fast, which may affect their contact effect with the substrate and lead to a decrease in adhesion.

[0039] (9) The present invention provides a method for preparing a photothermal superhydrophobic coating. In the preparation method, it is preferably dried at 80 °C to 100 °C for 30 min to 40 min; when the drying temperature is too low and the time is too short, the coating is not completely cured, resulting in unstable performance and easy damage during use; when the drying temperature is too high and the time is too long, it is easy to cause the coating to crack and lose its hydrophobicity. Description of the Drawings

[0040] Figure 1 Schematic diagram of the static water contact angle of the photothermal superhydrophobic coating prepared in Example 1.

[0041] Figure 2 Scanning electron microscope (SEM) image of the photothermal superhydrophobic coating prepared in Example 1.

[0042] Figure 3 Schematic diagram of the static water contact angle of the photothermal superhydrophobic coating prepared in Example 2.

[0043] Figure 4 Scanning electron microscope (SEM) image of the photothermal superhydrophobic coating prepared in Example 2.

[0044] Figure 5The time-lapse icing effect diagrams of the photothermal superhydrophobic coating (C-Fe3O4 superhydrophobic coating) prepared in Example 1 and the control group (uncoated fiberglass) at -20°C without light illumination.

[0045] Figure 6 The temperature increase effect diagrams of the photothermal superhydrophobic coating (C-Fe3O4 superhydrophobic coating) prepared in Example 1 and the control group (uncoated) under 1 sun intensity (1Sun, 1 W / cm 2 )

[0046] Figure 7 The time-lapse icing effect diagrams of the photothermal superhydrophobic coating (C-Fe3O4 superhydrophobic coating) prepared in Example 2 and the control group (uncoated fiberglass) at -20°C without light illumination.

[0047] Figure 8 The temperature increase effect diagrams of the photothermal superhydrophobic coating (C-Fe3O4 superhydrophobic coating) prepared in Example 2 and the control group (uncoated) under 1 sun intensity (1Sun, 1 W / cm 2 )

[0048] Figure 9 The static water contact angle schematic diagram of the photothermal superhydrophobic coating prepared in Comparative Example 1. Detailed implementation manners

[0049] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments, but it is not intended to limit the invention patent.

[0050] In the following embodiments:

[0051] The particle size of nano carbon black is 15 nm to 25 nm, and the particle size of nano Fe3O4 is 160 nm to 240 nm;

[0052] The air spraying gun model is R2-F with a 0.8 caliber, made by Baoli in Taiwan;

[0053] Contact angle and rolling angle test: Measured by the overall tilt platform contact angle measuring instrument model CA500, produced by Guangdong Beidou Precision Instruments Co., Ltd.;

[0054] Scanning electron microscope test: Using the field emission scanning electron microscope with the instrument model Zeiss Sigma 300, through the scientific compass detection agency platform;

[0055] Anti-icing performance test: Using the high and low temperature and humidity test chamber model JY-HJ-205, produced by Shanghai Juyi Instrument Equipment Co., Ltd.;

[0056] Photothermal performance test: Using the solar simulator model BBZM-Ⅲ, produced by Bobei Optical Factory.

[0057] Example 1

[0058] (1) Add 0.5 g of nano carbon black into 30 ml of absolute ethanol, stir manually for 1 min, then add 2.5 g of nano Fe3O4, stir manually for 1 min, and then ultrasonicate for 30 min with an ultrasonic power of 180 W to obtain a uniform nano-particle dispersion; add 1 ml of 1H,1H,2H,2H-perfluorodecyltrimethoxysilane, and then ultrasonicate for 30 min with an ultrasonic power of 180 W to obtain a modified nano-particle dispersion;

[0059] (2) Add 3 g of E-51 epoxy resin and 0.8 g of T-31 epoxy resin curing agent into 10 ml of ethyl acetate, stir at 50 °C for 2 h until evenly mixed to obtain an epoxy resin solution;

[0060] (3) Add the epoxy resin solution into the modified nano-particle dispersion and mix, ultrasonicate for 2 h with an ultrasonic power of 180 W, and ultrasonically disperse evenly to obtain a suspension of nano-particles and low surface energy mixture, which is the coating material suspension;

[0061] (4) Clean the surface of the substrate with ultrasonic cleaning to remove impurities such as dust and oil adhering to the surface of the substrate, and obtain a clean substrate, where the substrate is a fan blade made of fiberglass;

[0062] Adopt the air spraying process, set the air pressure to 0.3 MPa, the spraying angle to 90°, and the spraying distance to 15 cm. Use a spray gun to vertically spray the coating material suspension onto the clean substrate in 3 times; after spraying, dry at 100 °C for 40 min; a photothermal superhydrophobic coating is prepared on the substrate.

[0063] Perform the following performance tests on the photothermal superhydrophobic coating prepared in this example:

[0064] (1) Hydrophobic performance test

[0065] Test the static water contact angle and rolling angle of the coating. The results of the static water contact angle are as Figure 1 shown. The water contact angle is 158° and the rolling angle is 3°, showing excellent hydrophobic performance.

[0066] (2) Microscopic morphology observation

[0067] Observe the microscopic morphology of the coating. The results are as Figure 2 shown. The thickness of the coating is 130 μm. The surface of the coating film shows a typical villous structure. Nano carbon black particles and nano Fe3O4 particles are evenly dispersed in the coating, and the overlapping situation between particles is excellent. The formed micro-nano structure has a delicate structure and a tight and orderly arrangement, and the micro-nano composite effect is significant.

[0068] (3) Delayed icing effect test

[0069] The coating prepared in Example 1 was used as the experimental group, namely the C-Fe3O4 superhydrophobic coating. The substrate of the control group was the same as that of the example, but there was no coating on the surface, that is, uncoated fiberglass. The delayed icing effect diagrams of the experimental group and the control group at -20 °C without light are shown as Figure 5 shown

[0070] The substrate of the control group was completely frozen at 18 s, while the substrate with the coating in the experimental group was completely frozen at 20 min 15 s, which was 67.5 times that of the uncoated substrate in the control group, strongly proving that the coating prepared in Example 1 has excellent hydrophobic properties

[0071] (4) Photothermal performance effect test

[0072] The coating prepared in Example 1 was used as the experimental group, namely the C-Fe3O4 superhydrophobic coating. The substrate of the control group was the same as that of the example, but there was no coating on the surface, that is, uncoated. The heating-up effect diagrams of the experimental group and the control group under 1 sun intensity (1 Sun, 1 W / cm 2 ) are shown as Figure 7 shown

[0073] The results showed that the temperature of the substrate in the control group tended to be stable at 300 s, reaching about 44 °C. While the substrate with the coating in the experimental group rapidly heated up to 66 °C and tended to be stable after 240 s under the irradiation of 1 sun intensity, indicating that the coating prepared in Example 1 has good photothermal performance under light

[0074] Example 2

[0075] (1) Add 0.5 g of nano carbon black into 40 ml of absolute ethanol, stir manually for 1 min, then add 2 g of nano Fe3O4, stir manually for 1 min, and then ultrasonicate for 20 min with an ultrasonic power of 150 W to obtain a uniform nano-particle dispersion; add 1 ml of 1H,1H,2H,2H-perfluorodecyltrimethoxysilane, and then ultrasonicate for 20 min with an ultrasonic power of 150 W to obtain a modified nano-particle dispersion

[0076] (2) Add 4 g of E-51 epoxy resin and 1 g of T-31 epoxy resin curing agent into 20 ml of ethyl acetate, stir at 60 °C for 1 h until evenly stirred to obtain an epoxy resin solution

[0077] (3) Add the epoxy resin solution into the modified nano-particle dispersion and mix, ultrasonicate for 1 h with an ultrasonic power of 150 W, and ultrasonically disperse evenly to obtain a suspension of nano-particles and low surface energy mixture, which is the coating material suspension

[0078] (4) Clean the surface of the substrate by ultrasonic cleaning to remove impurities such as dust and oil adhering to the surface of the substrate, and obtain a clean substrate. The substrate is a fan blade made of fiberglass.

[0079] Adopt the air spraying process, set the air pressure to 0.2 MPa, the spraying angle to 90°, and the spraying distance to 10 cm. Use a spray gun to vertically spray the coating material suspension onto the clean substrate in 2 times; after spraying, dry it at 80 °C for 30 min; a photothermal superhydrophobic coating is prepared on the substrate.

[0080] Perform the following performance tests on the photothermal superhydrophobic coating prepared in this example:

[0081] (1) Hydrophobic performance test

[0082] Test the static water contact angle and rolling angle of the coating. The results of the static water contact angle are as Figure 3 shown. The water contact angle is 156°, and the rolling angle is 6°, showing relatively excellent hydrophobic performance.

[0083] (2) Microscopic morphology observation

[0084] Observe the microscopic morphology of the coating. The results are as Figure 4 shown. The thickness of the coating is 90 μm. The surface of the coating film shows a typical villous structure. The nano-carbon black particles and nano-Fe3O4 particles are evenly dispersed in the coating, and the particles are well overlapped. The formed micro-nano structure has a delicate structure and a tight and orderly arrangement, and the micro-nano composite effect is significant.

[0085] (3) Delayed icing effect test

[0086] The coating prepared in Example 2 is used as the experimental group, that is, the C-Fe3O4 superhydrophobic coating. The substrate of the control group is the same as that of the example, but there is no coating on the surface, that is, fiberglass without coating; test the delayed icing effect diagrams of the experimental group and the control group at -20 °C without light, as Figure 6 shown.

[0087] The results show that the substrate of the control group is completely frozen at 18 s, and the substrate with the coating in the experimental group is completely frozen at 9 min 47 s, which is 32.6 times that of the substrate without coating, strongly proving that the coating prepared in Example 2 has excellent hydrophobic performance.

[0088] (4) Photothermal performance effect test

[0089] The coating prepared in Example 2 was used as the experimental group, i.e., the C-Fe3O4 superhydrophobic coating. The substrate of the control group was the same as that of Example 2, but there was no coating on the surface, i.e., no coating. The heating effect diagrams of the experimental group and the control group under 1 sun intensity (1 Sun, 1 W / cm 2 ) are shown as Figure 8 follows.

[0090] The results showed that the temperature of the substrate in the control group tended to be stable at 300 s, reaching 44 °C. However, the substrate with the coating in the experimental group rapidly heated up to 61 °C and gradually tended to be stable after 270 s under the irradiation of 1 sun intensity. It can be seen that the coating prepared in Example 2 has relatively good photothermal performance under light.

[0091] The coating nanoparticles prepared in the above example were uniformly dispersed and crosslinked with epoxy resin, which not only improved the interaction between the nanoparticles, but also improved the adhesion between the coating and the substrate. After curing, the coating has good wear resistance and corrosion resistance, and the adhesion between the coating and the substrate is excellent.

[0092] Comparative Example 1

[0093] In Comparative Example 1, only based on Example 1, the ratio of carbon black to Fe3O4 was changed from 1:4.6 to 1:6, that is, 0.5 g of carbon black and 3 g of Fe3O4 were added as nanoparticles, and a coating was prepared on the substrate, and other conditions remained unchanged.

[0094] The following performance tests were carried out on the coating prepared in this comparative example:

[0095] The static water contact angle and rolling angle of the coating were tested. The results of the static water contact angle are shown as Figure 9 follows. The water contact angle was 146°, less than 150°, indicating that the coating lost the superhydrophobic effect. It was proved that the ratio of nano carbon black to nano Fe3O4 was crucial. The reason was that after the dosage of Fe3O4 exceeded the scope specified in this patent, there were too many nano Fe3O4 with larger particle sizes, resulting in an increase in the pores between Fe3O4 and Fe3O4, and the insufficient amount of nano carbon black with smaller particle sizes to fill all the pores, resulting in the aggregation of larger particle size Fe3O4, thus losing the superhydrophobic effect.

Claims

1. A photothermal superhydrophobic coating, characterized in that: In the coating material used for the said coating, the components and their weight parts are as follows: The particle size of the nano carbon black is 15 nm to 25 nm, and the particle size of the nano Fe3O4 is 160 nm to 240 nm; Prepare the said coating material into a suspension and spray it on the substrate to prepare a photothermal superhydrophobic coating.

2. The photo-thermal superhydrophobic coating according to claim 1, wherein: The thickness of the said coating is 90 μm to 130 μm.

3. The one kind of photothermal superhydrophobic coating according to claim 1 or 2, characterized in that: The substrate of the said coating is fiberglass.

4. The one kind of photothermal superhydrophobic coating according to claim 3, wherein: The substrate of the said coating is a fan blade made of fiberglass.

5. A method for preparing a photothermal superhydrophobic coating according to any one of claims 1 to 4, characterized in that: (1) Add nano carbon black and nano Fe3O4 into absolute ethanol successively and disperse them evenly by ultrasonic wave, then add 1H,1H,2H,2H-perfluorodecyltrimethoxysilane and disperse them evenly by ultrasonic wave further to obtain a modified nano-particle dispersion liquid; (2) Add epoxy resin and curing agent into ethyl acetate and stir evenly to obtain an epoxy resin solution; (3) Add the epoxy resin solution into the modified nano-particle dispersion liquid and mix, and disperse them evenly by ultrasonic wave to prepare a coating material suspension; (4) Spray the coating material suspension on the clean substrate and dry it to prepare a photothermal superhydrophobic coating.

6. The preparation method of a photothermal superhydrophobic coating according to claim 5, characterized in that: In step (4), air spraying is adopted, specifically: use a spray gun to vertically spray the coating material suspension on the clean substrate, the spraying distance is 10 cm to 15 cm, and the air pressure is 0.2 MPa to 0.3 MPa.

7. The preparation method of a photothermal superhydrophobic coating according to claim 5, characterized in that: In step (1), nano carbon black and nano Fe3O4 are added into absolute ethanol successively and dispersed by ultrasonic wave, the ultrasonic time is 20 min to 30 min, and the ultrasonic power is 150 W to 180 W; add 1H,1H,2H,2H-perfluorodecyltrimethoxysilane and disperse them evenly by ultrasonic wave further, the ultrasonic time is 20 min to 30 min, and the ultrasonic power is 150 W to 180 W.

8. The preparation method of a photothermal superhydrophobic coating according to claim 5, characterized in that: In step (2), the epoxy resin is E-51 epoxy resin; the curing agent is T-31 epoxy resin curing agent; add the epoxy resin and the curing agent into ethyl acetate and stir at 50 °C to 60 °C for 1 h to 2 h to stir evenly.

9. The preparation method of a photothermal superhydrophobic coating according to claim 5, wherein: In step (3), add the epoxy resin solution into the modified nano-particle dispersion liquid and mix, the ultrasonic time for ultrasonic dispersion is 1 h to 2 h, and the ultrasonic power is 150 W to 180 W.

10. The preparation method of a photothermal superhydrophobic coating according to claim 5, characterized in that: In step (4), the clean substrate is obtained by cleaning the surface of the substrate by ultrasonic cleaning to remove the dust and oil adhered to the surface of the substrate; dry it at 80 °C to 100 °C for 30 min to 40 min.

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