Simple and convenient method for forming fluoride-free super-hydrophobic iron-based photo-thermal frost prevention and removal composite coating based on unsaturated fatty acid one-step high-temperature treatment

Abstract

The invention relates to the field of super-hydrophobic composite coatings, in particular to a simple and convenient method for forming a fluorine-free super-hydrophobic iron-based photo-thermal frost prevention and removal composite coating based on unsaturated fatty acid one-step high-temperature treatment, which comprises the following steps: by taking intrinsic hydrophilic reduced iron powder as a matrix, adjusting the treatment ratio of unsaturated fatty acid high-temperature oil bath, and preparing the fluorine-free super-hydrophobic iron-based photo-thermal frost prevention and removal composite coating. And meanwhile, nano-scale heat-conducting particles are introduced, so that the fluorine-free super-hydrophobic iron-based photo-thermal frost prevention and removal particles are prepared in one step. The experiment steps are simple and safe, the prepared product has excellent super-hydrophobic performance, a particle coating is constructed through a thermal bonding method, and the fluorine-free super-hydrophobic iron-based photo-thermal anti-defrosting composite coating with good frosting delaying and photo-thermal rapid defrosting capacity in the extreme refrigeration environment is obtained in combination with the good photo-thermal performance of the particle coating.

Description

Technical Field

[0001] The invention relates to the field of super-hydrophobic composite coatings, and specifically to a simple method for forming a fluorine-free super-hydrophobic iron-based photothermal anti-defrosting composite coating based on one-step high-temperature treatment of unsaturated fatty acids. Background Art

[0002] Photothermal composite materials are multifunctional materials that can efficiently absorb solar energy and convert it into thermal energy. They are special performance materials formed by artificially compounding two or more materials with different properties. This characteristic of photothermal composite materials gives them great potential in solving the energy crisis. In recent years, photothermal composite materials have been widely used in seawater desalination, temperature difference power generation, wearable health monitoring and other fields with high efficiency and environmental protection.

[0003] As global climate change intensifies, extreme weather events occur frequently, especially in high-latitude areas and cold seasons. The formation and accumulation of frost has a serious impact on various infrastructure and transportation vehicles. In the fields of aviation, electricity, construction, transportation, etc., the accumulation of frost will not only lead to a decline in equipment performance and increased energy consumption, but may also cause mechanical failures and structural damage, posing a major threat to operational safety. Therefore, the research on efficient and environmentally friendly anti-defrosting technology has become a scientific and technological issue that needs to be solved urgently.

[0004] Traditional defrosting methods mainly include mechanical defrosting, chemical defrosting and electric heating defrosting. Although these methods can solve the frost problem to a certain extent, they often have shortcomings such as high energy consumption, low efficiency, high cost and environmental pollution. For example, mechanical defrosting requires a lot of energy and manpower, and may damage the surface of the equipment; chemical defrosting may cause chemical pollution and secondary treatment problems; although electric heating defrosting is direct and effective, it consumes a lot of energy, and long-term operation may accelerate equipment aging.

[0005] In recent years, passive defrosting technology has gradually attracted attention due to its advantages such as low energy consumption and environmental protection. Among them, photothermal anti-defrosting technology, as an emerging passive defrosting method, has attracted much attention due to its high photothermal conversion efficiency and clean energy utilization. Photothermal anti-defrosting / defrosting coatings absorb solar energy and convert it into thermal energy to increase the surface temperature of the coating, thereby preventing the formation of frost or accelerating the melting of frost. However, a single photothermal coating still has certain limitations in the anti-defrosting process. For example, the low energy density and intermittent nature of solar energy limit the development of all-weather anti-defrosting technology; at the same time, a single coating material often cannot simultaneously meet the requirements of efficient photothermal conversion and excellent anti-defrosting performance. Therefore, combining photothermal materials with other functional materials to develop multifunctional composite anti-defrosting coatings has become a research hotspot.

[0006] As a functional material with excellent waterproof and anti-fouling properties, superhydrophobic coatings have also shown great potential in the field of anti-frost in recent years. By increasing the hydrophobicity of the coating surface, superhydrophobic coatings reduce the capture rate of supercooled water droplets in the air on the coating surface, thereby achieving the purpose of anti-frost. However, a single superhydrophobic coating may still face the problem of ice and frost accumulation in extremely cold and humid environments.

[0007] Based on the above background, the research on photothermal anti-frost composite coatings has emerged. This composite coating combines a photothermal material with a superhydrophobic coating to achieve all-weather and efficient anti-frost effects through synergistic effects. Specifically, the photothermal material is responsible for absorbing solar energy and converting it into heat energy to increase the surface temperature of the coating; the superhydrophobic coating, through its excellent hydrophobicity, delays the formation of ice and frost and reduces the adhesion strength between ice and the coating surface. The combination of the two not only overcomes the limitations of a single coating in the anti-frost process but also achieves efficient and environmentally friendly anti-frost effects. By coating a superhydrophobic coating on the surface of the device, it is difficult for the droplets condensed on the surface to adhere, thereby forming a "water-repellent" property on the surface, effectively preventing the uniform growth of the frost layer, thus effectively preventing the formation of frost, significantly improving the heat exchange efficiency and refrigeration effect of the equipment, reducing energy consumption and maintenance costs, and having important practical application value. Summary of the Invention

[0008] In order to solve the problems of the existing anti-frost composite coatings, such as complex preparation processes, high prices, the need for specific equipment, and no other additional functions, by mixing and adding each reactant in the same reaction vessel and carrying out continuous reactions simultaneously under high-temperature oil bath, this invention avoids the lengthy separation process and intermediate purification process, and provides a simple method for forming a fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating through one-step high-temperature treatment of unsaturated fatty acids. This not only shortens the experimental process and reduces costs but also endows the iron-based coating with superhydrophobicity and discovers the performance of delaying frost formation. Its combination with the photothermal effect under light conditions can achieve photothermal defrosting, so it has potential application value in the fields of photothermal anti-frost and so on.

[0009] This invention uses reduced iron powder as the reactant and unsaturated fatty acid as the reaction solvent. Through the esterification reaction between the native hydroxyl groups on the original reduced iron powder and the carboxyl groups in the unsaturated fatty acid, hydrophobic modification is carried out. Coupled with adjusting the dosage of nano-silicon carbide, fluorine-free superhydrophobic iron-based photothermal anti-frost composite coatings with different wettability effects and photothermal properties are prepared. Using the prepared fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating as the structural unit, a fluorine-free superhydrophobic iron-based photothermal anti-frost coating with both superhydrophobic anti-frost function and photothermal effect is constructed, and its wetting performance, anti-frost performance, photothermal performance, and photothermal defrosting performance are explored.

[0010] To achieve the above-mentioned invention objectives, the technical solution provided by the present invention is a simple method for forming a fluorine-free superhydrophobic iron-based photothermal defrosting composite coating through one-step high-temperature treatment of unsaturated fatty acids. The method includes the following steps:

[0011] Take a certain amount of reduced iron powder and place it in unsaturated fatty acids; add nano-scale heat-conducting particles and make the nano-scale heat-conducting particles uniformly dispersed in the system;

[0012] Place the system in a high-temperature oil bath for reaction. After the reaction, wash it several times and dry it to obtain a fluorine-free superhydrophobic iron-based photothermal defrosting composite coating.

[0013] Preferably, the unsaturated fatty acids are linolenic acid and linoleic acid.

[0014] Preferably, the mixing ratio of the unsaturated fatty acids is linolenic acid:linoleic acid = 1:1.

[0015] Preferably, the mass ratio of the amount of reduced iron powder used to the amount of unsaturated fatty acids used is 1:5.

[0016] Preferably, the nano-scale heat-conducting particles are silicon carbide, and the mass ratio of the silicon carbide to the reduced iron powder is 1:10 - 7:10.

[0017] Preferably, the temperature of the oil bath reaction is 140 °C, the reaction time is 7.5 h, wash it with absolute ethanol until the absolute ethanol is clear and transparent after washing, and vacuum dry it for 2 h.

[0018] The second aspect of the present invention provides a fluorine-free superhydrophobic iron-based photothermal defrosting composite coating prepared by using the above-mentioned method.

[0019] The third aspect of the present invention provides the application of the fluorine-free superhydrophobic iron-based photothermal defrosting composite coating in the fields of frost prevention for precision instrument equipment and photothermal defrosting, etc.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) The present invention provides a simple method for forming a fluorine-free superhydrophobic iron-based photothermal defrosting composite coating through one-step high-temperature treatment of unsaturated fatty acids. By adopting an experimental method of one-step synthesis, it avoids the long separation process and intermediate purification process, shortens the experimental process, and reduces the time cost; the preparation process is simple and does not require the use of large and expensive equipment.

[0022] (2) The present invention uses a simple and efficient method with intrinsically hydrophilic reduced iron powder as the base material, and endows the reduced iron powder with superhydrophobicity by using unsaturated fatty acids. The experimental raw materials are easy to obtain, the experimental cost is low, the operation is convenient, it is fluorine-free and environmentally friendly, and has broad market prospects.

[0023] (3) The fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating prepared by the present invention has good water repellency and anti-fouling self-cleaning properties. It can also rapidly heat up under light conditions, exhibiting a photothermal effect, and can achieve excellent anti-frost performance in a refrigeration environment. Combining with the photothermal effect, it can achieve photothermal defrosting, and has potential application value in the field of anti-frost for precision instrument equipment. Description of the Drawings

[0024] Figure 1 Shows the water contact angle and rolling angle of the fluorine-free superhydrophobic iron-based photothermal anti-frost composite coatings prepared in Examples 1-7 of the present invention;

[0025] Figure 2 Shows the anti-fouling self-cleaning performance demonstration diagram of the fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating prepared in Example 5 of the present invention;

[0026] Figure 3 Shows the temperature change curves of the fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating prepared in Example 5 of the present invention and the comparative example within 0-300 s under one sun intensity irradiation;

[0027] Figure 4 Shows the infrared thermal imaging diagrams of the fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating prepared in Example 5 of the present invention and the comparative example within 0-300 s under one sun intensity irradiation;

[0028] Figure 5 Shows the frost layer growth diagrams obtained by observing the coating surface from the side of the fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating prepared in Example 5 of the present invention and the comparative example during continuous refrigeration for 1800 s;

[0029] Figure 6 Shows the frost layer growth thickness change curves of the fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating prepared in Example 5 of the present invention and the comparative example during continuous refrigeration for 1800 s;

[0030] Figure 7 Shows the frost layer coverage rate curves of the fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating prepared in Example 5 of the present invention and the comparative example during continuous refrigeration for 3600 s;

[0031] Figure 8 Shows the temperature change curves of the fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating prepared in Example 5 of the present invention and the comparative example within 3600 s under one sun intensity irradiation in a continuous refrigeration environment;

[0032] Figure 9 The defrosting state and infrared thermal imaging diagrams of the coating surface over time of the fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating prepared in Example 5 of the present invention under one sun intensity irradiation in a non-refrigeration environment;

[0033] Figure 10 The defrosting state of the surface of the fluorine-free superhydrophobic iron-based photothermal defrosting composite coating prepared in Example 5 of the present invention over time during natural defrosting in a non-refrigerated environment and the infrared thermal imaging diagram. Detailed implementation manners

[0034] To make the above objects, features, and advantages of the present invention more apparent and understandable, the following will describe in detail the specific implementation manners of the present invention with reference to the accompanying drawings. Many specific details are set forth in the following description to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0035] Example 1

[0036] The present invention provides a simple method for forming a fluorine-free superhydrophobic iron-based photothermal defrosting composite coating through one-step high-temperature treatment based on unsaturated fatty acids, which includes the following steps:

[0037] Step S100: Weigh 1 g of reduced iron powder and add it to a glass container. Then add 2.5 ml of linolenic acid, 2.5 ml of linoleic acid, and 0.1 g of nano silicon carbide to the glass container, and then stir evenly with a glass rod to obtain a mixed solution; react the mixed solution under the condition of oil bath heating at 140 °C for 7.5 h to obtain a particle suspension system for use.

[0038] Step S200: Clean the particle suspension system obtained in step S100. Use a magnet to apply an external magnetic force to make the particle products in the suspension system sink to the bottom, and use absolute ethanol to wash to remove the related compounds and functional reagents that have not reacted completely. After washing 5 times, remove the absolute ethanol washing solution.

[0039] Step S300: Place the product obtained in step S200 in a vacuum dryer and dry it for 2 h to finally obtain a fluorine-free superhydrophobic iron-based photothermal defrosting composite coating, denoted as FLLTH@SiC-NSM-1.

[0040] Disperse the above-prepared FLLTH@SiC-NSM-1 particles evenly in absolute ethanol, and use it as a structural unit to construct a fluorine-free superhydrophobic iron-based photothermal defrosting composite coating on a solid substrate by thermal bonding. First, evenly coat 0.5 ml of a methacrylic resin binder on the solid substrate, and place it in an oven at 80 °C for a period of time to form a sticky surface on the solid substrate. Then, use the drop-coating method to evenly distribute the FLLTH@SiC-NSM-1 particles on the sticky surface, and place it in a thermal environment at 80 °C for 1 h to obtain a fluorine-free superhydrophobic iron-based photothermal defrosting composite coating.

[0041] Example 2

[0042] Step S100: Weigh 1 g of reduced iron powder and add it to a glass container. Then add 2.5 ml of linolenic acid, 2.5 ml of linoleic acid and 0.2 g of nano-silicon carbide to the glass container. After that, use a glass rod to stir evenly to obtain a mixed solution. React the mixed solution under the condition of oil bath heating at 140 °C for 7.5 h to obtain a particle suspension system for use.

[0043] Step S200: Clean the particle suspension system obtained in step S100. Use a magnet to add an external magnetic force to make the particle products in the suspension system sink to the bottom, and use absolute ethanol to clean to remove the related compounds and functional reagents that have not reacted completely. After cleaning 5 times, remove the absolute ethanol cleaning solution.

[0044] Step S300: Place the product obtained in step S200 in a vacuum dryer and dry it for 2 h to finally obtain a fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating, denoted as FLLTH@SiC-NSM-2.

[0045] And use FLLTH@SiC-NSM-2 particles as structural units to construct a fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating. The coating preparation steps are the same as those in Example 1.

[0046] Example 3

[0047] Step S100: Weigh 1 g of reduced iron powder and add it to a glass container. Then add 2.5 ml of linolenic acid, 2.5 ml of linoleic acid and 0.3 g of nano-silicon carbide to the glass container. After that, use a glass rod to stir evenly to obtain a mixed solution. React the mixed solution under the condition of oil bath heating at 140 °C for 7.5 h to obtain a particle suspension system for use.

[0048] Step S200: Clean the particle suspension system obtained in step S100. Use a magnet to add an external magnetic force to make the particle products in the suspension system sink to the bottom, and use absolute ethanol to clean to remove the related compounds and functional reagents that have not reacted completely. After cleaning 5 times, remove the absolute ethanol cleaning solution.

[0049] Step S300: Place the product obtained in step S200 in a vacuum dryer and dry it for 2 h to finally obtain a fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating, denoted as FLLTH@SiC-NSM-3.

[0050] And use FLLTH@SiC-NSM-3 particles as structural units to construct a fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating. The coating preparation steps are the same as those in Example 1.

[0051] Example 4

[0052] Step S100: Weigh 1 g of reduced iron powder and add it to a glass container. Then, add 2.5 ml of linolenic acid, 2.5 ml of linoleic acid, and 0.4 g of nano-silicon carbide to the glass container. After that, use a glass rod to stir evenly to obtain a mixed solution. React the mixed solution under the condition of oil bath heating at 140 °C for 7.5 h to obtain a particle suspension system for later use.

[0053] Step S200: Clean the particle suspension system obtained in Step S100. Use a magnet to apply an external magnetic force to make the particle products in the suspension system sink to the bottom, and use absolute ethanol to clean to remove the incompletely reacted related compounds and functional reagents. After cleaning 5 times, remove the absolute ethanol cleaning solution.

[0054] Step S300: Place the product obtained in Step S200 in a vacuum dryer and dry it for 2 h to finally obtain a fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating, denoted as FLLTH@SiC-NSM-4.

[0055] And use FLLTH@SiC-NSM-4 particles as the structural unit to construct a fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating. The coating preparation steps are the same as those in Example 1.

[0056] Example 5

[0057] Step S100: Weigh 1 g of reduced iron powder and add it to a glass container. Then, add 2.5 ml of linolenic acid, 2.5 ml of linoleic acid, and 0.5 g of nano-silicon carbide to the glass container. After that, use a glass rod to stir evenly to obtain a mixed solution. React the mixed solution under the condition of oil bath heating at 140 °C for 7.5 h to obtain a particle suspension system for later use.

[0058] Step S200: Clean the particle suspension system obtained in Step S100. Use a magnet to apply an external magnetic force to make the particle products in the suspension system sink to the bottom, and use absolute ethanol to clean to remove the incompletely reacted related compounds and functional reagents. After cleaning 5 times, remove the absolute ethanol cleaning solution.

[0059] Step S300: Place the product obtained in Step S200 in a vacuum dryer and dry it for 2 h to finally obtain a fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating, denoted as FLLTH@SiC-NSM-5.

[0060] And use FLLTH@SiC-NSM-5 particles as the structural unit to construct a fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating. The coating preparation steps are the same as those in Example 1.

[0061] Example 6

[0062] Step S100: Weigh 1 g of reduced iron powder and add it to a glass container. Then add 2.5 ml of linolenic acid, 2.5 ml of linoleic acid, and 0.6 g of nano silicon carbide to the glass container. Then use a glass rod to stir evenly to obtain a mixed solution. React the mixed solution under the condition of oil bath heating at 140 °C for 7.5 h to obtain a formed particle suspension system for later use.

[0063] Step S200: Clean the particle suspension system obtained in Step S100. Use a magnet to add an external magnetic force to make the particle products in the suspension system sink to the bottom, and use absolute ethanol to clean to remove the related compounds and functional reagents that have not reacted completely. After cleaning 5 times, remove the absolute ethanol cleaning solution.

[0064] Step S300: Place the product obtained in Step S200 in a vacuum dryer and dry it for 2 h to finally obtain a fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating, denoted as FLLTH@SiC-NSM-6.

[0065] And use FLLTH@SiC-NSM-6 particles as the structural unit to construct a fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating. The coating preparation steps are the same as those in Example 1.

[0066] Example 7

[0067] Step S100: Weigh 1 g of reduced iron powder and add it to a glass container. Then add 2.5 ml of linolenic acid, 2.5 ml of linoleic acid, and 0.7 g of nano silicon carbide to the glass container. Then use a glass rod to stir evenly to obtain a mixed solution. React the mixed solution under the condition of oil bath heating at 140 °C for 7.5 h to obtain a formed particle suspension system for later use.

[0068] Step S200: Clean the particle suspension system obtained in Step S100. Use a magnet to add an external magnetic force to make the particle products in the suspension system sink to the bottom, and use absolute ethanol to clean to remove the related compounds and functional reagents that have not reacted completely. After cleaning 5 times, remove the absolute ethanol cleaning solution.

[0069] Step S300: Place the product obtained in Step S200 in a vacuum dryer and dry it for 2 h to finally obtain a fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating, denoted as FLLTH@SiC-NSM-7.

[0070] And use FLLTH@SiC-NSM-7 particles as the structural unit to construct a fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating. The coating preparation steps are the same as those in Example 1.

[0071] Table 1 is the summary table of the added material masses in Examples 1 to 7;

[0072]

[0073] Comparative Example

[0074] Using reduced iron powder as a structural unit, a reduced iron powder coating surface was constructed on a solid substrate by thermal bonding. Other conditions were the same as those in the preparation steps of the coating in Example 1. The difference between this comparative example and the above-mentioned examples was that the reduced iron powder used was a hydrophilic material itself.

[0075] It should be noted that, compared with Examples 1 to 7, the preparation steps were basically the same, only the dosages of some reagents were adjusted, and the ratios were different. See Table 1. The products of Examples 1 to 7 were respectively subjected to wetting property tests, anti-fouling and self-cleaning performance tests, photothermal performance tests, anti-frosting performance tests, photothermal defrosting performance tests, etc. The product characteristics were not very different. The test process of the product in Example 5 will be used as an example for illustration below.

[0076] I. Conduct a wetting property test on the fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating. See Figure 1 ;

[0077] The specific measurement methods for the wetting property include:

[0078] Step H100, Static water contact angle measurement: Drop 5 μL of deionized water on five different areas of the sample, and use the instrument to measure the contact angle of each water droplet, and then take the average of these measured values to obtain the data of the static water contact angle.

[0079] Step H200, Rolling angle determination: By adjusting the angle on the tilting table, when 10 μL of deionized water is dropped at five different positions on the sample and can roll, record and fix this specific angle, and this angle is the rolling angle of the sample.

[0080] Step H300, Static moisture resistance observation: Drop water droplets on the surface of the sample and observe the static state of the water droplets to evaluate the moisture resistance of the sample.

[0081] Among them, from Figure 1It can be seen that the water contact angles of the fluorine-free superhydrophobic iron-based photothermal defrosting composite coatings obtained in Examples 1 to 7 are greater than or equal to 150°, and the rolling angles are less than or equal to 10°, showing extreme anti-wetting ability to the aqueous phase. However, the reduced iron powder used as a comparative example contains a large number of hydrophilic groups in itself, which makes it easily wetted by the aqueous phase, and the measured water contact angle is 0°. According to the method adopted in the embodiments of the present invention, using reduced iron powder as a raw material, endowing it with superhydrophobic performance and photothermal defrosting performance. This is mainly because the native hydroxyl groups of reduced iron powder react with the carboxyl groups in unsaturated fatty acids under high-temperature conditions, forming ester bonds between them, and then introducing the long alkyl chains of unsaturated fatty acids to achieve the hydrophobic modification effect. In addition, nanoscale SiC is attached to the particle surface, greatly improving its surface roughness and making the hierarchical difference more significant, forming a micro-nano rough surface and endowing the sample with superhydrophobicity.

[0082] II. Perform the anti-fouling and self-cleaning performance test of the fluorine-free superhydrophobic iron-based photothermal defrosting composite coating, see Figure 2 ;

[0083] Specific test method for anti-fouling and self-cleaning performance: Test the fluorine-free superhydrophobic iron-based photothermal defrosting composite coating prepared in Example 5. Use sand and gravel as the pollutant model, drop water droplets on the inclined coating, and evaluate the self-cleaning performance of the coating by observing the effect of the water droplets removing the pollutant soil. Then, use juice, cola, tea, milk, milk tea, coffee, and dye sewage as the pollutant models respectively. Place the coating on an inclined platform and evaluate the anti-fouling ability of the coating by the state of the pollutants dropped on the coating.

[0084] Figure 2 This is the display diagram of the anti-fouling and self-cleaning performance of the fluorine-free superhydrophobic iron-based photothermal defrosting composite coating prepared in Example 5 of the present invention. As Figure 2 (a) shows, sand particles are evenly distributed on the surface of the fluorine-free superhydrophobic iron-based photothermal defrosting composite coating. By continuously dropping water droplets, the sand particles on the coating surface will roll off the coating surface together with the water droplets, and there are no sand particles and water droplets remaining on the coating surface, showing good self-cleaning performance. Figure 2 (b) to (g) are the rolling processes of milk, milk tea, dye sewage, coffee, grape juice, and peach juice on the surface of the fluorine-free superhydrophobic iron-based photothermal defrosting composite coating in sequence. After the pollutants are dropped on the inclined super-black coating surface, they roll off quickly and there is no residue.

[0085] III. Perform the photothermal performance test of the fluorine-free superhydrophobic iron-based photothermal defrosting composite coating, see Figures 3 - 4 ;

[0086] Specific test method for photothermal performance: The fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating prepared in Example 5 was tested. A xenon lamp light source with an AM 1.5G filter was used to simulate a standard sunlight with a power density of 1000 W m -2 . The simulated sunlight was vertically irradiated on the coating surface for 0 s to 300 s, and an infrared thermal imager was used to test the temperature change on the surface of the coating material.

[0087] As Figure 3 and 4 shown, when testing the temperature response of the fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating, as the irradiation time of the xenon lamp increased, the temperature on the coating surface also continued to rise, and its surface temperature changed rapidly with the start of irradiation. At an irradiance of 1 sun, the surface temperature of the coating rapidly rose to 53.9 °C within the first 120 seconds and reached an equilibrium temperature of approximately 66.0 °C after 300 seconds of irradiation. This phenomenon indicates that the coating can efficiently convert the absorbed light energy into heat energy, thereby achieving rapid heating, which provides a solid foundation for the photothermal anti-frost performance. During the 300-second test time, the surface temperature of the untreated comparative coating only reached 39.3 °C, which is much lower than the surface temperature of the fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating, further confirming the superiority of the fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating in terms of photothermal conversion efficiency.

[0088] IV. The anti-frost performance of the fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating was tested. Refer to Figures 5 - 7 ;

[0089] Specific test method for anti-frost performance: The fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating prepared in Example 5 was tested. A refrigeration table was used to simulate a refrigeration environment. The fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating and the comparative example were placed on the refrigeration table and refrigerated for 3600 s, and the frosting situation on the coating surface was observed.

[0090] As Figure 5 and 6 shown in 7, when testing the anti-frost performance of the fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating, as the refrigeration time increased, the frost layer on the surface of the comparative example grew faster. After 1800 s, it was approximately twice the length of the frost layer growth of the coating in Example 5, indicating that the fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating has obvious anti-frost performance. And the frost layer coverage rate of the comparative coating reached 100% at 900 s. When the coating in Example 5 was refrigerated for 3600 s, the surface of the coating was still partially frosted, and the frost layer coverage rate was 41.15%. It shows that the fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating has excellent anti-frost performance compared to the comparative coating.

[0091] V. Perform the photothermal defrosting performance test on the fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating. Refer to Figures 8 - 10 ;

[0092] Specific test method for photothermal defrosting performance: Test the fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating prepared in Example 5. After placing the coating on a refrigeration table until its surface is completely frosted, use a xenon lamp light source with an AM 1.5G filter to simulate a standard sunlight with a power density of 1000 W m -2 . Simulate the standard sunlight vertically irradiating the surface of the coating in a continuous refrigeration environment for 0 s to 3600 s, and use an infrared thermal imager to test the temperature change of the coating surface.

[0093] As Figure 8 shown, when performing the photothermal defrosting performance test on the fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating, as the light irradiation progresses, the surface temperature of the fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating reaches above zero at 240 s. And as the subsequent refrigeration proceeds, although its temperature fluctuates, it remains above zero, while the temperature of the comparative coating remains below zero. This shows that the fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating can exert its excellent photothermal performance to achieve anti-frost application under good light irradiation conditions.

[0094] As Figure 9 、 10 shown, when performing the photothermal defrosting performance test on the fluorine-free superhydrophobic iron-based photothermal anti-frost composite coating, after turning off the refrigeration table, let Example 5 defrost naturally without xenon lamp irradiation. Its natural defrosting takes 187 s. With the help of an infrared thermal image, it is found that its temperature rises slowly. When defrosting under the irradiation of a sunlight intensity, it is found that the temperature of Example 5 rises rapidly, and complete defrosting can be achieved in 50 s. And as the light irradiation continues, the surface temperature of the coating continues to rise. After 70 s, the surface temperature reaches 15 °C. Thus, it can be seen that using solar energy can achieve rapid defrosting, without the supply of external energy, without generating secondary pollution or causing damage to refrigeration equipment, and can quickly and effectively remove frost, and can be applied to the anti-frost field of precision instrument equipment.

[0095] In addition, it should be understood that the above-described embodiments are only used to explain the present invention in detail, but the present invention is not limited to the above detailed methods. For those skilled in the art, within the spirit and principle of the present invention, any improvement to the present invention, the equivalent replacement of each raw material of the present invention product, the selection of specific methods, etc., should all be covered within the protection scope and disclosure scope of the present invention.

Claims

1. A simple method for forming a fluorine-free super-hydrophobic iron-based light-heat anti-defrosting composite coating based on one-step high-temperature treatment of unsaturated fatty acids, characterized in that: The following steps are involved: A certain amount of reduced iron powder is placed in unsaturated fatty acid; nano-scale thermal conductive particles are added and the nano-scale thermal conductive particles are evenly dispersed in the system; The system is placed in a high-temperature oil bath for reaction, and after the reaction, it is washed several times and dried to obtain a fluorine-free super-hydrophobic iron-based photothermal anti-defrosting composite coating.

2. A simple method for forming a fluorine-free super-hydrophobic iron-based light-heat-defrost-proof composite coating based on one-step high-temperature treatment of unsaturated fatty acids according to claim 1, characterized in that: The unsaturated fatty acids are linolenic acid and linoleic acid.

3. According to the simple method for forming a fluorine-free super-hydrophobic iron-based light-heat anti-defrosting composite coating based on one-step high-temperature treatment of unsaturated fatty acids as described in claim 2, it is characterized in that: The mixed ratio of the unsaturated fatty acids is linolenic acid:linoleic acid=1:

1.

4. The simple method for forming a fluorine-free super-hydrophobic iron-based light-heat-defrost-proof composite coating based on one-step high-temperature treatment of unsaturated fatty acids according to claim 1, characterized in that: The mass ratio of the reduced iron powder to the unsaturated fatty acid is 1:

5.

5. The simple method for forming a fluorine-free super-hydrophobic iron-based light-heat anti-defrosting composite coating based on one-step high-temperature treatment of unsaturated fatty acids according to claim 1, characterized in that: The nano-scale thermally conductive particles are silicon carbide, and the mass ratio of the silicon carbide to the reduced iron powder is 1:10 to 7:

10.

6. The simple method for forming a fluorine-free super-hydrophobic iron-based light-heat-defrost-proof composite coating based on one-step high-temperature treatment of unsaturated fatty acids according to claim 1, characterized in that: The temperature of the oil bath reaction was 140 °C, the reaction time was 7.5 h, and the product was washed with anhydrous ethanol until the anhydrous ethanol was clear and transparent after washing, and then dried in vacuum for 2 h.

7. A fluorine-free super-hydrophobic iron-based light-heat-defrost-proof composite coating is realized based on one-step high-temperature treatment of unsaturated fatty acids, characterized in that: The coating is prepared by a simple method for forming a fluorine-free super-hydrophobic iron-based photothermal anti-defrosting composite coating based on one-step high-temperature treatment of unsaturated fatty acids as described in any one of claims 1-6.

8. According to claim 7, the fluorine-free super-hydrophobic iron-based photothermal anti-defrosting composite coating based on unsaturated fatty acid one-step high-temperature treatment has the performance of delaying frosting and photothermal defrosting, and is applied to the anti-frost field of precision instruments and equipment.

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