Anti-icing super-hydrophobic coating compositely prepared by laser electro-deposition

Abstract

The invention discloses an anti-icing super-hydrophobic coating compositely prepared by laser electrodeposition. A preparation method of the anti-icing super-hydrophobic coating comprises the following steps: step S1, constructing a micron-sized grid structure on the surface of a matrix by adopting a laser processing technology through a transverse and longitudinal straight line equal-interval cross scanning mode; the distance between every two adjacent straight lines is 50-200 [mu] m; performing ultrasonic cleaning on the sample subjected to laser processing, putting the sample into a diluted hydrochloric acid solution, and etching for 1 hour at the temperature of 60 DEG C; and S2, the substrate treated in the step S1 serves as an anode, the initial substrate serves as a cathode, electrochemical deposition is conducted in electrolyte, and the super-hydrophobic coating is obtained on the anode through deposition. The prepared super-hydrophobic coating is good in anti-icing performance, under the conditions that the environment temperature is-15 DEG C and the relative humidity is 50%, a common aluminum sheet can be iced within 30 seconds, a treated super-hydrophobic sample shows remarkable anti-icing performance, and the maximum icing delay time can reach 900 seconds.

Description

Technical Field

[0001] The present invention relates to the technical field of superhydrophobic materials, and in particular to a superhydrophobic coating prepared by laser electro-deposition composite for anti-icing. Background Art

[0002] The formation of ice is a common natural phenomenon. However, in many engineering fields, the accumulation or icing of ice can bring serious problems, such as economic losses, equipment failures, and safety hazards. For example, icing on the surface of an aircraft can affect aerodynamic performance, increase flight resistance, reduce lift, and even lead to accidents. Icing on transmission lines and substation equipment may cause power outages or equipment damage. Superhydrophobic surfaces are a special type of functional material obtained by constructing surface micro-nano structures and modifying them with low surface energy substances. Superhydrophobic surfaces can inhibit ice nucleation. By reducing the contact area between water and the surface and lowering the interfacial adhesion energy, superhydrophobic surfaces can inhibit the formation of ice nuclei. Superhydrophobic surfaces can reduce the adhesion strength of ice. Even if ice forms on a superhydrophobic surface, its adhesion strength is relatively low, and the ice layer is more easily removed by external forces such as wind blowing or vibration.

[0003] Currently, many studies have applied superhydrophobic surfaces to anti-icing. Mechanical durability has an important impact on the anti-icing performance of superhydrophobic surfaces. The mechanical stability of surface micro-nano structures and low surface energy coatings is the key to maintaining superhydrophobicity and anti-icing performance. Moreover, superhydrophobicity requires that the surface microstructure can accommodate the trapped air between the liquid-solid interfaces. However, most of the existing superhydrophobic coatings have problems such as single function and poor comprehensive performance. For example, superhydrophobic coatings prepared by electro-deposition and high-temperature curing methods may have poor mechanical durability. Huang X, Sun M, et al. created a transparent superhydrophobic coating with a customized nano-cone array structure through initiated chemical vapor deposition (iCVD). The optimized nano-cone array coating exhibited excellent water repellency, as well as outstanding anti-icing and anti-frosting performance. However, the nano-cone array structure provides a "point contact" mode, with a sufficient air layer between the water droplet and the surface, which reduces the liquid-solid interface and inhibits heat conduction. Electrochemical deposition is an efficient and cost-effective technique for preparing superhydrophobic surfaces. Parameters such as current density, voltage, time, and solution concentration during the preparation of superhydrophobic surfaces by electrochemical deposition can be precisely controlled, thereby achieving the regulation of coating thickness, morphology, and composition to meet different application requirements. However, there are still deficiencies in aspects such as mechanical stability and bonding strength, which in turn affect the anti-icing effect. Summary of the Invention

[0004] Aiming at the problem that the comprehensive performance of the current superhydrophobic coatings for anti-icing is imperfect and affects the anti-icing effect, the present invention provides a superhydrophobic coating prepared by laser electro-deposition composite for anti-icing.

[0005] The superhydrophobic coating prepared by laser electro-deposition composite for anti-icing provided by the present invention has the following preparation method:

[0006] S1. Using laser processing technology, a micron-scale grid structure is constructed on the surface of the substrate by means of equidistant cross-scanning in horizontal and vertical straight lines. Among them, the distance between adjacent straight lines is 50-200 μm; the sample after laser processing is ultrasonically cleaned and then put into a dilute hydrochloric acid solution for etching at 60 °C for 1 h.

[0007] Preferably, the number of laser scanning processes is 10-20 times.

[0008] S2. Electrochemical deposition is carried out on the basis of laser processing;

[0009] Taking the substrate treated in step S1 as the anode and the initial substrate as the cathode, electrochemical deposition is carried out in the electrolyte, and a superhydrophobic coating is deposited on the anode. After electrochemical deposition, the obtained sample is put into an oven and dried at 60 °C for 60 min.

[0010] Preferably, the substrate is an aluminum plate.

[0011] Preferably, the electrolyte is prepared by mixing myristic acid, absolute ethanol and magnesium chloride hexahydrate as raw materials, heating to 50 °C and stirring for 60 min.

[0012] Preferably, the voltage of the electrochemical deposition is 5 V and the deposition time is 60 min.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0014] (1) The superhydrophobic coating of the present invention has good anti-icing performance: under the conditions of an environmental temperature of -15 °C and a relative humidity of 50%, ordinary aluminum sheets can freeze within 30 seconds, while the treated superhydrophobic samples show significant anti-icing performance, and the ice formation delay time can reach up to 900 seconds at most.

[0015] (2) The superhydrophobic coating of the present invention has good mechanical wear resistance: the superhydrophobic coating loses its superhydrophobicity only after being worn for 240 cm.

[0016] (3) The preparation method of the superhydrophobic coating of the present invention is simple and feasible: the micro-nano structure formed by laser processing can significantly reduce the contact area between the liquid droplet and the surface. Combining with the functional coating of electrochemical deposition, the liquid droplet maintains "point contact" and forms a stable air layer (air cushion effect), thereby effectively inhibiting heat conduction and delaying the ice formation time.

[0017] Other advantages, objects and features of the present invention will be partly reflected by the following description, and partly will be understood by those skilled in the art through the research and practice of the present invention. Description of the Drawings

[0018] Figure 1 It is a laser processing path diagram.

[0019] Figure 2 It is a surface topography diagram of an aluminum plate after laser processing with different spacings, where (a), (b), and (c) are spacings of 50 μm, 100 μm, and 200 μm respectively.

[0020] Figure 3 It is a schematic diagram of an electrochemical deposition experimental device.

[0021] Figure 4 It is an elemental analysis diagram of the surface microstructure of the coating prepared in Example 1.

[0022] Figure 5 It is the surface topography of the coating electrochemically deposited on the original aluminum plate without laser processing.

[0023] Figure 6 It is the surface topography of the coating electrochemically deposited on the aluminum plate after laser processing.

[0024] Figure 7 It is a diagram of the ice formation process on the surface of the original aluminum plate.

[0025] Figure 8 It is a diagram of the ice formation process of the coating directly electrochemically deposited on the original aluminum plate.

[0026] Figure 9 It is a diagram of the ice formation process of the superhydrophobic coating electrochemically deposited on the aluminum plate after laser processing.

[0027] Figure 10 It is a schematic diagram of the mechanical durability test method.

[0028] Figure 11 It is a diagram of the mechanical durability test result.

[0029] Figure 12 It is a diagram of the ice formation time test results of the superhydrophobic coating with different spacings and different processing times. Detailed Embodiments

[0030] The following is a description of the preferred embodiments of the present invention with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0031] Example 1

[0032] A superhydrophobic coating prepared by laser-electrodeposition composite for anti-icing, and the preparation steps are as follows:

[0033] (1) Preparation of grid structure: Place the aluminum plate on the laser workbench and process it according to the Figure 1 shown processing path. Using laser processing technology, perform cross-scanning at equal intervals in the horizontal and vertical directions in a straight line. The distance between two adjacent parallel straight lines is controlled to be 50 μm. Repeat the laser processing 10 times, and finally form a micron-level grid structure on the aluminum plate. The processed sample is cleaned in an ultrasonic cleaner with deionized water and absolute ethanol for 10 minutes each to remove the surface Al 2 O 3 Then, place the sample in a 0.2 mol / L dilute hydrochloric acid solution for etching for 1 hour at an etching temperature of 60 °C to obtain the Figure 2 aluminum plate surface structure shown in (a).

[0034] (2) Preparation of electrolyte: Mix 16.8 g of myristic acid (CH 3( CH 2 ) 12 COOH), 50 ml of absolute ethanol, and 12 g of magnesium chloride hexahydrate (MgCl 2 (H 2 O) 6 and stir in an oil bath stirrer for 60 minutes at a temperature of 50 °C to obtain the electrolyte.

[0035] (3) Preparation of superhydrophobic coating by electrochemical deposition: Fix the aluminum plate sample obtained in step (1) with an electrode clamp as the anode, and use the original aluminum plate without laser treatment as the cathode. Place them in the electrolyte obtained in step (2) for electrochemical deposition for 60 minutes at a deposition voltage of 5 V. After electrochemical deposition, place the obtained sample in an oven for drying for 60 minutes at a temperature of 60 °C. The electrochemical deposition experimental device is arranged in parallel at a distance of 2 cm as shown in Figure 3 . The reaction equations are as follows:

[0036] CH 3 (CH 2 ) 12 COOH → CH 3 (CH 2 ) 12 COO - + H +

[0037] Al - 3e - → Al 3+

[0038] 2H + + 2e - → H 2

[0039] CH 3 (CH 2 ) 12COO - +Al 3+ →Al[CH 3 (CH 2 ) 12 COO] 3

[0040] Example 2

[0041] On the basis of Example 1, the number of laser processing times in step (1) was changed to 15 times, and other steps remained unchanged.

[0042] Example 3

[0043] On the basis of Example 1, the number of laser processing times in step (1) was changed to 20 times, and other steps remained unchanged.

[0044] Example 4

[0045] On the basis of Example 1, the spacing between adjacent two straight lines in step (1) was controlled to be 100 μm, and the aluminum plate surface structure shown in Figure 2 (b) was obtained, and other steps remained unchanged.

[0046] Example 5

[0047] On the basis of Example 4, the number of laser processing times in step (1) was changed to 15 times, and other steps remained unchanged.

[0048] Example 6

[0049] On the basis of Example 4, the number of laser processing times in step (1) was changed to 20 times, and other steps remained unchanged.

[0050] Example 7

[0051] On the basis of Example 1, the spacing between adjacent two straight lines in step (1) was controlled to be 200 μm, and the aluminum plate surface structure shown in Figure 2 (c) was obtained, and other steps remained unchanged.

[0052] Example 8

[0053] On the basis of Example 7, the number of laser processing times in step (1) was changed to 15 times, and other steps remained unchanged.

[0054] Example 9

[0055] On the basis of Example 7, the number of laser processing times in step (1) was changed to 20 times, and other steps remained unchanged.

[0056] In the method for preparing the superhydrophobic coating of the present invention, first, a micron-scale grid structure is formed by laser processing. The introduction of the grid structure not only improves the mechanical stability of the sample surface but also significantly enhances its durability. When the spacing between the laser processing paths is small, the grid structure is denser, forming a fine surface texture, which is beneficial to improving the micro-nano composite structure of the surface and providing a higher roughness for the superhydrophobic performance. However, too small a spacing may cause excessive overlap or insufficient melting of the material, resulting in irregular surface morphology or accumulation. When the spacing increases, the sparsity of the grid structure increases, and the surface roughness decreases. If the spacing is too large, there may be insufficient connection between the grids, leading to a decrease in mechanical stability and superhydrophobic performance. The present invention provides Figure 2 three sizes of spacings as shown. On the basis of laser processing, an electrochemical deposition experiment is carried out. The electrochemical deposition voltage is an important parameter affecting the coating quality. At a lower voltage, the deposition process is relatively slow, and the deposition particles of metals or compounds are usually smaller, and the coating is more uniform and smooth. For a superhydrophobic surface, this may not be conducive to forming sufficient micro-nano rough structures. A higher voltage will cause the deposition rate to increase, the coating particles to become larger, and even form a porous or hierarchical structure. Such a rough surface is more conducive to achieving superhydrophobicity, but too high a voltage may cause irregular deposition, resulting in an increased risk of surface defects or peeling. Therefore, a suitable voltage range needs to be selected. The present invention uses a deposition voltage of 5V.

[0057] The results of the surface element analysis of the coating prepared in Example 1 are shown in Figure 4 , and it can be seen that the main microstructural elements on the coating surface are Al, C, and O, which proves that aluminum myristate is formed.

[0058] On the basis of Example 1, step (1) is omitted, and the original aluminum plate is directly used for electrochemical deposition. The SEM image of the prepared coating surface is as shown in Figure 5 , and the micro-nano structure on the coating surface is relatively loose. The SEM image of the coating surface prepared in Example 1 is as shown in Figure 6 , and nano-particles and dendritic myristic acid are grown on the sample surface. These nano-structures appear as small, dense, and relatively uniform dot-like or strip-like distributions in the image, which are denser than the Figure 5 surface structure. Moreover, the contact angle test results show that the contact angle of the surface of the electrochemical deposition coating without laser processing is 157.4°, and the contact angle of the surface of the coating after laser processing and then electrochemical deposition reaches 160.454°. This shows that laser processing further significantly enhances the superhydrophobic performance of the coating surface.

[0059] Anti-icing experiment tests were conducted on the surface of the original aluminum plate, the superhydrophobic surface formed by direct electrodeposition on the original aluminum plate, and the superhydrophobic surface formed by laser-electrodeposition in Example 1. Test method: Anti-icing experiment: Test samples of 4 cm × 2 cm × 2 mm were placed in an environment with a temperature of -15 °C and a humidity of 50%, and the icing process was observed. The results are as Figure 7 , 8 , as shown in Figure 9. The surface of the original aluminum plate was completely iced at 30 s. The superhydrophobic surface formed by direct electrodeposition on the original aluminum plate was completely iced at 534 s. However, the superhydrophobic surface formed by the combination of laser and electrodeposition in the present invention was completely iced only at 900 s. This is because the micro-nano structure significantly enhances the anti-icing performance. The laser and electrodeposition composite process generates a more refined hierarchical micro-nano structure. These structures effectively reduce the contact area between the water droplet and the solid surface, and at the same time form a stable air cushion layer, reducing the heat conduction efficiency and delaying the icing process. Moreover, the improvement of surface roughness can improve the anti-icing performance. Laser processing further increases the surface roughness. After combining with the electrodeposition technology, a multi-scale structure is constructed, making it more difficult for the liquid droplets to spread and adhere to the surface, thus hindering the formation and growth of ice nuclei. Wear experiments were conducted on the superhydrophobic coatings directly electrodeposited on the original aluminum plate and the superhydrophobic coatings electrodeposited after laser processing. The mechanical durability test method is as Figure 10 shown. The test sample with a size of 4 cm × 2 cm × 2 mm was fixed at the bottom of a 100 g weight and pulled on 1000-mesh sandpaper at a uniform speed. Each 20 cm of pulling was counted as one wear cycle, and the change in the surface contact angle was tested once to characterize the surface wettability. The test results are shown in Figure 11 . It can be seen that the superhydrophobic coating on the surface of the original aluminum plate without laser processing lost its superhydrophobicity after 140 cm of wear, while the superhydrophobic coating electrodeposited on the aluminum plate after laser processing lost its superhydrophobicity only after 240 cm of wear. This shows that laser processing significantly enhances the bonding strength between the coating and the substrate. The multi-scale structure generated by laser processing can effectively disperse the external stress, reduce the local stress concentration, and improve the anti-wear performance and overall mechanical stability of the coating.

[0060] In the preparation of the superhydrophobic coating of the present invention, the spacing between adjacent two straight lines during laser processing and the number of repeated laser processing times will both affect the anti-icing performance of the finally formed superhydrophobic coating. The test results of the icing time of the superhydrophobic coatings with different spacings and different processing times are shown in Figure 12 . It can be seen from the results that when the number of processing times is 10 and the path spacing is 200 μm, the anti-icing performance of the obtained superhydrophobic coating is the best, reaching 900 s.

[0061] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the disclosed technical content within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A super-hydrophobic coating prepared by laser electrodeposition for anti-icing, characterized in that: The preparation method is as follows: S1, using laser processing technology to construct a micron-scale grid structure on the substrate surface by horizontal and vertical straight line equal spacing cross scanning; S2, electrochemical deposition based on laser processing; The substrate treated in step S1 is used as an anode, and the initial substrate is used as a cathode. Electrochemical deposition is performed in an electrolyte to deposit a super-hydrophobic coating on the anode.

2. The super-hydrophobic coating prepared by laser electrodeposition composite for anti-icing according to claim 1, characterized in that: In step S1, the spacing between adjacent straight lines is 50-200 μm.

3. The super-hydrophobic coating prepared by laser electrodeposition composite for anti-icing according to claim 1, characterized in that: Step S1 also includes, after ultrasonic cleaning, placing the laser processed sample in a dilute hydrochloric acid solution and etching at a temperature of 60° C. for 1 hour.

4. The super-hydrophobic coating prepared by laser electrodeposition composite for anti-icing according to claim 1, characterized in that: In step S1, the number of laser scanning processing is 10-20 times.

5. The super-hydrophobic coating prepared by laser electrodeposition composite for anti-icing according to claim 1, characterized in that: The substrate is an aluminum plate.

6. The super-hydrophobic coating prepared by laser electrodeposition composite for anti-icing according to claim 5, characterized in that: The electrolyte is prepared by mixing myristic acid, anhydrous ethanol and magnesium chloride hexahydrate as raw materials, heating to 50° C. and stirring for 60 minutes.

7. The super-hydrophobic coating prepared by laser electrodeposition for anti-icing according to claim 6, characterized in that: The voltage of the electrochemical deposition is 5V, and the deposition time is 60min.

8. The super-hydrophobic coating prepared by laser electrodeposition for anti-icing according to claim 7, characterized in that: After electrochemical deposition, the obtained sample was placed in an oven and dried at 60°C for 60 min.

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