A method for preparing a low-surface-energy super-hydrophobic coating on a copper alloy surface

Abstract

The application belongs to the field of surface modification of metal materials, and particularly relates to a preparation method of a low-surface-energy super-hydrophobic coating on a copper alloy surface, comprising the following steps: firstly, pretreating the metal, configuring a MOF ligand solution, preparing a MOF film layer on the copper alloy surface, configuring a calcium chloride-stearic acid-anhydrous ethanol low-energy modification solution, and immersing the MOF film layer sample in the low-energy solution to obtain the low-surface-energy super-hydrophobic coating. The preparation method has simple steps, low requirements for equipment and process, and fast preparation. The prepared coating has good adhesion with the copper alloy, can be uniformly distributed on the metal surface, has very low surface energy, can reach super-hydrophobicity, has good corrosion resistance and self-cleaning performance, and prolongs the service life of the copper alloy.

Description

Technical Field

[0001] This invention belongs to the field of surface modification of metallic materials, and specifically relates to a method for preparing a low surface energy superhydrophobic coating on a copper alloy surface. Background Technology

[0002] Copper alloys are widely used in the manufacture of seawater pipeline systems and ships due to their good resistance to seawater corrosion and biofouling. They are gradually taking a leading position in the application of marine materials. However, the corrosion behavior of copper alloys is not uniform corrosion but localized corrosion. Copper alloys have been in the extremely complex seawater environment for a long time. Due to localized corrosion, various leakage and failure accidents often occur in seawater systems and ships using copper alloys as materials.

[0003] Current research on the corrosion resistance of copper alloys mainly focuses on alloying, surface strengthening, electroless plating, and the application of corrosion inhibitors. Alloying introduces other elements into the copper alloy to achieve corrosion resistance, but the introduction of these elements can also lead to a decrease in other physical properties of the copper alloy. Surface strengthening uses physical methods to treat the surface, refining the grains and reducing surface microporosity. This method is mainly used to overcome corrosion caused by stress, but it is not very effective against chemical corrosion. Electroless plating and the application of corrosion inhibitors have become hot topics in recent years. Electroless plating covers the metal surface with a layer of metal to protect the internal metal, while corrosion inhibitors isolate the corrosive medium to a certain extent to achieve the effect of corrosion inhibition.

[0004] MOFs (Metal-Organic Fabrics) are porous materials with high specific surface areas. They are three-dimensional porous networks formed by metal ions and organic ligands according to specific coordination relationships. MOFs are resistant to high temperatures and do not easily decompose or volatilize. Their high specific surface area and porous structure can support corrosion inhibitors and be applied in the field of corrosion-resistant materials. Superhydrophobic surfaces are defined as surfaces with a contact angle greater than 150° and a roll-off angle less than 10° between the liquid and the substrate. Due to their water-repellent properties, superhydrophobic surfaces have broad application prospects in corrosion protection. In recent years, significant breakthroughs have been achieved in the research and development of superhydrophobic coatings. Superhydrophobic coatings possess high contact angle micro-wetting characteristics, which can alter the water-sensitive properties of MOFs materials.

[0005] CN112522703A discloses a fluorine-free superhydrophobic Zn-MOF composite coating on a magnesium alloy surface and its preparation method. Specifically, it discloses a method for preparing a superhydrophobic coating by using micro-arc oxidation, high-temperature and high-pressure reaction, and superhydrophobic modification. In this patent, the preparation of the MOF coating utilizes a high-temperature and high-pressure reaction, and the reaction conditions are relatively harsh, making it difficult to widely promote and apply.

[0006] Therefore, whether a better superhydrophobic treatment method can be provided to improve the corrosion resistance of copper alloys has become one of the technical problems that urgently need to be solved by those skilled in the art. Summary of the Invention

[0007] This invention provides a method for preparing a low surface energy superhydrophobic coating on a copper alloy surface, comprising the following steps: first, pretreating the metal; preparing a MOF ligand solution; preparing a low-energy modification solution of calcium chloride stearic acid and anhydrous ethanol; and immersing the MOF film sample in the low-energy solution to obtain the low surface energy superhydrophobic coating. The above preparation method is simple, requires low equipment and process specifications, and is fast. The prepared coating has good adhesion to the copper alloy and can be uniformly distributed on the metal surface. The coating has very low surface energy, achieves superhydrophobicity, and exhibits good corrosion resistance and self-cleaning properties, thus extending the service life of the copper alloy.

[0008] The main inventive concept of this invention is that in the prior art, the solution of using a metal framework structure on the surface of copper alloy to achieve the anti-corrosion effect requires the introduction of other metal ions to form an organometallic skeleton structure. However, the construction process mostly requires high temperature and high pressure reaction, which is difficult to operate and has a high risk factor.

[0009] MOF-199 is a MOF material formed by the coordination of copper ions and trimesic acid. However, due to its water-sensitive properties, it cannot achieve the slow release of the corrosion inhibitor in the liquid. This invention utilizes the metal ions provided by the metal material itself to form an organometallic framework. Taking advantage of the characteristics of anodic oxidation and the in-situ growth of metal ions provided by the metal itself, a mild and rapid reaction is carried out to construct the MOF-199 superhydrophobic coating at room temperature and under a relatively low DC voltage.

[0010] The specific technical solution of the present invention is as follows: A method for preparing a low surface energy superhydrophobic coating on a copper alloy surface, the specific preparation method including the following steps: (1) Metal pretreatment: copper alloy is selected for cleaning and rust removal, and then ultrasonically cleaned with acetone, ethanol and deionized water in sequence, and then dried for later use. The copper alloy used in this application may be selected from C7701 copper alloy, B10 copper alloy, or aluminum brass.

[0011] (2) Preparation of MOF-199 ligand solution: Zinc acetate and 1,3,5-benzenetricarboxylic acid were added to a mixed solvent of pure water, anhydrous ethanol and N,N dimethylformamide in a volume ratio of 1:1:1. The mixture was stirred and shaken to dissolve the solution completely, and the MOF-199 ligand solution was obtained for later use. In the above steps, the concentration of zinc acetate is 0.05-0.15 mol / L, the concentration of 1,3,5-benzenetricarboxylic acid is 0.5-0.7 mol / L, and the temperature is room temperature; In the prior art, the construction of MOF in a benzoic acid solution alone has the disadvantages of slow growth, uneven growth, or even no growth of MOF. In this application, by introducing zinc acetate, firstly, a strong electrolyte is added to the solution, which improves the conductivity of the solution. Secondly, the introduction of acetate ions promotes the formation of MOF. In practical applications, the inventors discovered that without the addition of zinc acetate, the formation of MOFs under the same conditions is greatly affected. Even if a MOF coating is formed, it suffers from weak metal adhesion and shallow thickness. However, with the addition of zinc acetate, the MOF coating has good adhesion, increased thickness, and significantly improved formation efficiency.

[0012] (3) Preparation of low surface energy solution: Anhydrous calcium chloride and stearic acid are added to anhydrous ethanol, heated and stirred at low speed to dissolve, and the low surface energy solution is set aside for later use. In the above steps, the concentration of anhydrous calcium chloride is 0.05-0.15 mol / L, and the concentration of stearic acid is 0.1-0.2 mol / L; (4) Preparation of coating: The pretreated copper alloy was placed in MOF-199 ligand solution as the anode, and a graphite sheet of the same size was used as the cathode. The anode was connected to a DC power supply for anodizing for a period of time. Then it was taken out and rinsed with deionized water, dried and placed in calcium chloride stearic acid anhydrous ethanol solution for a period of time. Then it was taken out and cleaned with anhydrous ethanol and dried. The surface of the copper alloy was coated with low surface energy MOF-199 superhydrophobic coating.

[0013] In the above steps, the distance between the two electrodes during anodic oxidation is 25 mm, the anodic oxidation voltage is 20-40 V, and the oxidation time is 10-30 min; the immersion time in the low surface energy solution is 3-5 h. Preferably, the above conditions are: oxidation voltage of 30V, oxidation time of 15min, and immersion time in low surface energy solution of 4h.

[0014] The purpose of anodizing is to generate copper ions from the oxidation of copper alloys to provide metal ions for the generation of MOF, while the purpose of immersion is to allow low surface energy materials to adhere to the sample surface.

[0015] The above preparation method utilizes the characteristic of anodic oxidation to generate ions on the sample surface. Combined with a ligand solution, a simple and rapid MOF-199 film with good bonding force can be grown in situ on the sample surface, giving the sample surface a certain micro-nano rough structure. Then, by modifying it with a low surface energy material, a MOF-199 coating with a low surface energy micro-nano rough structure is formed. The sample has superhydrophobicity, which improves the corrosion resistance of copper alloy.

[0016] Preferably, the cleaning and rust removal steps in step (1) are as follows: the copper alloy is polished by passing it through metallographic sandpaper of #240, #600, #1000 and #1500 in sequence.

[0017] Preferably, in step (2), the zinc acetate concentration is 0.1 mol / L, the concentration of 1,3,5-benzenetricarboxylic acid is 0.6 mol / L, and the temperature is room temperature.

[0018] Preferably, in step (2), the stirring speed is 300-360 rpm and the stirring time is 15 min.

[0019] Preferably, in step (3), the concentration of anhydrous calcium chloride is 0.1 mol / L and the concentration of stearic acid is 0.1 mol / L.

[0020] The above preparation method is simple in steps and requires simple equipment and processes. The prepared coating has good adhesion to the copper metal surface and can be evenly distributed on the metal surface. The coating surface has very low surface energy, good hydrophobic effect and can reach superhydrophobicity. It has good corrosion resistance and cleanability, and extends the service life of copper alloy.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) No roughening treatment is required on the metal surface, which avoids uneven and difficult-to-control etching process and avoids damage to the substrate material and the environment. (2) MOF-199 with a large specific surface area was stably synthesized on the surface, providing a new approach for future use with corrosion inhibitors; (3) The adhesion of the low surface energy MOF coating makes it difficult for corrosive media to approach the copper alloy substrate, increases hydrophobicity, increases the corrosion resistance of the copper alloy, and extends the service life of the copper alloy. (4) The copper alloy is subjected to anodizing, soaking and other operations, which improves the hydrophobicity and corrosion resistance of the copper alloy. The process does not involve high temperature and high pressure, high voltage and high current, and the operation is simple and safe. Attached Figure Description

[0022] Figure 1 The image shows the contact angle test results of the copper alloy low surface energy coating obtained in Example 1. Figure 2 This is a comparison diagram of the electrochemical impedance spectroscopy test results of the copper alloy low surface energy coating prepared in Example 1 and the blank sample substrate. Figure 3 This is a comparison of the electrochemical impedance spectroscopy results of the copper alloy low surface energy coating prepared in Example 2 and the blank sample substrate. Figure 4 This is a comparison of the electrochemical impedance spectroscopy results of the low surface energy copper alloy coating prepared in Example 3 and the blank sample substrate. Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. The copper alloy dimensions in the following embodiments are all 40*20*2mm. Example 1

[0024] A method for preparing a low surface energy nanocoating on a copper alloy surface: (1) Copper alloy pretreatment C7701 copper alloy was selected and polished sequentially with #240, #600, #1000, and #1500 metallographic sandpaper to clean and remove rust. Then, the surface was rinsed with deionized water to remove surface residue. Next, it was ultrasonically cleaned with acetone, ethanol, and deionized water for 10 minutes each, and then dried for later use. The ultrasonic cleaning was performed at a frequency of 28KHz, and the acetone, ethanol, and deionized water completely submerged the C7701 copper alloy. (2) Preparation of MOF-199 ligand solution Prepare 150 ml of a mixed solution of 0.1 mol / L zinc acetate and 0.6 mol / L 1,3,5-benzenetricarboxylic acid using a mixed solvent consisting of pure water, anhydrous ethanol and DMF in a volume ratio of 1:1:1. Stir vigorously for 15 min at a stirring speed of 360 rpm and then sonicate for 10 min.

[0025] (3) Preparation of low surface energy solutions Prepare 150 ml of a solution of 0.1 mol / L anhydrous calcium chloride and 0.1 mol / L stearic acid using anhydrous ethanol. Heat the solution to 40°C and stir vigorously for 30 min to disperse the calcium chloride evenly. The stirring speed is 360 rpm. This will yield a low surface energy solution.

[0026] (4) Coating preparation The pretreated C7701 copper alloy was placed in MOF-199 ligand solution for anodic oxidation. The copper alloy was used as the anode and the graphite sheet of the same size was used as the cathode. The distance between the two electrodes was 25 mm, the oxidation voltage was 30 V, and the oxidation time was 15 min. The surface was then rinsed with deionized water, dried, and cooled to room temperature. The treated C7701 copper alloy was immersed in a low surface energy solution for 4 hours, then rinsed with anhydrous ethanol, dried and cooled to room temperature, and then placed in a drying oven at 60°C for 2 hours to obtain a low surface energy superhydrophobic coating.

[0027] Comparative Example 1 A method for preparing a low surface energy nanocoating on a copper alloy surface: (1) Copper alloy pretreatment C7701 copper alloy was selected and polished sequentially with metallographic sandpaper of #240, #600, #1000, and #1500 to clean and remove rust. Then, the surface was rinsed with deionized water to remove surface residue. Next, it was ultrasonically cleaned with acetone, ethanol, and deionized water for 10 minutes each, and then dried for later use. During ultrasonic cleaning, the acetone, ethanol, and deionized water completely submerged the C7701 copper alloy. (2) Preparation of MOF-199 ligand solution Prepare 150 ml of a mixed solution of 0.2 mol / L zinc acetate and 0.5 mol / L 1,3,5-benzenetricarboxylic acid using a mixed solvent of pure water, anhydrous ethanol, and DMF in a ratio of 1:1:1. Stir vigorously for 15 min at a stirring speed of 360 rpm and then sonicate for 10 min.

[0028] (3) Preparation of low surface energy solutions Prepare 150 ml of a solution of 0.1 mol / L anhydrous calcium chloride and 0.1 mol / L stearic acid using anhydrous ethanol. Heat the solution to 40°C and stir vigorously for 30 min to disperse the calcium chloride evenly. The stirring speed is 360 rpm. This will yield a low surface energy solution.

[0029] (4) Coating preparation The pretreated C7701 copper alloy was placed in a MOF-199 ligand solution for anodic oxidation. The copper alloy was used as the anode and a graphite sheet of the same size was used as the cathode. The distance between the two electrodes was 25 mm, the oxidation voltage was 30 V, and the oxidation time was 15 min. The surface was then rinsed with deionized water, dried, and cooled to room temperature. The treated C7701 copper alloy was then immersed in a low surface energy solution for 4 h, rinsed with anhydrous ethanol, dried, and cooled to room temperature. Finally, it was placed in a drying oven at 60 °C for 2 h to obtain a low surface energy superhydrophobic coating.

[0030] Experimental Example 1 For the C7701 copper alloy surface coatings prepared in Example 1 and Comparative Example 1, the contact angle of the coating surface was measured using a contact angle meter. The measurement was performed using the stop-drop method with a 3µL water droplet. The contact angle of Example 1 was measured to be 152.4°. Figure 1 As shown in the figure, the C7701 copper alloy surface coating prepared has superhydrophobicity.

[0031] Electrochemical tests were performed on the coating using an electrochemical workstation with a three-electrode system. The working electrode was a C7701 copper alloy surface coating, the reference electrode was a saturated calomel electrode, and the auxiliary electrode was a platinum sheet. The electrolyte was a 3.5% sodium chloride solution. The corrosion resistance of the coating surface was tested using electrochemical impedance spectroscopy. The impedance arc represents the corrosion resistance of the coating; a larger impedance arc indicates better corrosion resistance. The results were fitted using Z-View software, as shown below. Figure 2 As shown, the total impedance of the uncoated C7701 copper alloy is 4224.6 Ω•cm. 2 In Example 1, the total impedance of the coated C7701 copper alloy was 28118 Ω•cm. 2 Compared with the uncoated copper alloy, the coating of the present invention greatly improves the corrosion resistance of C7701 copper alloy. The difference between Comparative Example 1 and the Example is that different reactant concentrations are used. The MOF-199 coating in Comparative Example 1 was not successfully constructed. Only by using the specific ligand solution of the present invention can a copper alloy superhydrophobic coating with good corrosion resistance and MOF-199 coating be obtained. Example 2

[0032] A method for preparing a low surface energy nanocoating on a copper alloy surface: (1) Copper alloy pretreatment B10 copper alloy was selected and polished sequentially with metallographic sandpaper of #240, #600, #1000, and #1500 to clean and remove rust. Then, the surface was rinsed with deionized water to remove surface residue. Next, it was ultrasonically cleaned with acetone, ethanol, and deionized water for 10 minutes each, and then dried for later use. The ultrasonic cleaning was performed at a frequency of 28KHz, and the acetone, ethanol, and deionized water were completely submerged in the B10 copper alloy. (2) Preparation of MOF-199 ligand solution Prepare 150 ml of a mixed solution of 0.1 mol / L zinc acetate and 0.58 mol / L 1,3,5-benzenetricarboxylic acid using a mixed solvent consisting of pure water, anhydrous ethanol and DMF in a volume ratio of 1:1:1. Stir vigorously for 15 min at a stirring speed of 360 rpm and then sonicate for 10 min.

[0033] (3) Preparation of low surface energy solutions Prepare 150 ml of a solution of 0.1 mol / L anhydrous calcium chloride and 0.1 mol / L stearic acid using anhydrous ethanol. Heat the solution to 40°C and stir vigorously for 30 min to disperse the calcium chloride evenly. The stirring speed is 360 rpm. This will yield a low surface energy solution.

[0034] (4) Coating preparation The pretreated B10 copper alloy was placed in a MOF-199 ligand solution for anodic oxidation. The copper alloy was used as the anode and a graphite sheet of the same size was used as the cathode. The distance between the two electrodes was 25 mm, the oxidation voltage was 25 V, and the oxidation time was 16 min. The surface was then rinsed with deionized water, dried, and cooled to room temperature. The treated B10 copper alloy was then immersed in a low surface energy solution for 4 h, rinsed with anhydrous ethanol, dried, and cooled to room temperature. Finally, it was placed in a drying oven at 60 °C for 2 h to obtain a low surface energy superhydrophobic coating.

[0035] Electrochemical tests were performed on the coating using an electrochemical workstation with a three-electrode system. The working electrode was a B10 copper alloy surface coating, the reference electrode was a saturated calomel electrode, and the auxiliary electrode was a platinum sheet. The electrolyte was a 3.5% sodium chloride solution. The corrosion resistance of the coating surface was tested using electrochemical impedance spectroscopy. The impedance arc represents the corrosion resistance of the coating; a larger impedance arc indicates better corrosion resistance. The results were fitted using Z-View software. Figure 3 As shown, the total impedance of the uncoated B10 copper alloy is 341.1 Ω•cm. 2 In Example 2, the total impedance of the coated B10 copper alloy was 28172 Ω•cm. 2 Compared with the uncoated B10 copper alloy, the coating of the present invention greatly improves the corrosion resistance of the B10 copper alloy. The difference between Example 2 and Example 1 is that different copper alloys are used. According to the electrochemical impedance spectroscopy data, the present invention can also be applied to B10 copper alloy. Example 3

[0036] A method for preparing a low surface energy nanocoating on a copper alloy surface: (1) Copper alloy pretreatment Aluminum brass is selected and polished sequentially with metallographic sandpaper of #240, #600, #1000, and #1500 to clean and remove rust. Then, the surface is rinsed with deionized water to remove surface residue. Next, it is ultrasonically cleaned with acetone, ethanol, and deionized water for 10 minutes each, and then dried for later use. The ultrasonic cleaning is performed at a frequency of 28KHz, and the aluminum brass is submerged in acetone, ethanol, and deionized water. (2) Preparation of MOF-199 ligand solution Prepare 150 ml of a mixed solution of 0.11 mol / L zinc acetate and 0.61 mol / L 1,3,5-benzenetricarboxylic acid using a mixed solvent consisting of pure water, anhydrous ethanol and DMF in a volume ratio of 1:1:1. Stir vigorously for 15 min at a stirring speed of 360 rpm and then sonicate for 10 min.

[0037] (3) Preparation of low surface energy solutions Prepare 150 ml of a solution of 0.1 mol / L anhydrous calcium chloride and 0.1 mol / L stearic acid using anhydrous ethanol. Heat the solution to 40°C and stir vigorously for 30 min to disperse the calcium chloride evenly. The stirring speed is 360 rpm. This will yield a low surface energy solution.

[0038] (4) Coating preparation The pretreated aluminum brass was anoly oxidized in a MOF-199 ligand solution, with a copper alloy as the anode and an equally sized graphite sheet as the cathode. The distance between the two electrodes was 25 mm, the oxidation voltage was 35 V, and the oxidation time was 20 min. The surface was then rinsed with deionized water, dried, and cooled to room temperature. The treated aluminum brass was then immersed in a low surface energy solution for 4 h, rinsed with anhydrous ethanol, dried, and cooled to room temperature. Finally, it was placed in a 60 °C drying oven for 2 h to obtain a low surface energy superhydrophobic coating.

[0039] Electrochemical tests were performed on the coating using an electrochemical workstation with a three-electrode system. The working electrode was an aluminum brass surface with a superhydrophobic coating, the reference electrode was a saturated calomel electrode, and the auxiliary electrode was a platinum sheet. The electrolyte was a 3.5% sodium chloride solution. The corrosion resistance of the coating surface was tested using electrochemical impedance spectroscopy. The impedance arc represents the corrosion resistance of the coating; a larger impedance arc indicates better corrosion resistance. The results were fitted using Z-View software. Figure 4 As shown, the total impedance of uncoated aluminum brass is 3692.1 Ω•cm. 2 In Example 3, the coated aluminum brass had a total impedance of 27372 Ω•cm. 2 Compared with uncoated aluminum brass, the coating of the present invention greatly improves the corrosion resistance of aluminum brass. The difference between Example 3 and Example 1 is that different copper alloys are used. According to the electrochemical impedance spectroscopy data, the present invention can also be applied to aluminum brass.

[0040] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a low surface energy superhydrophobic coating on a copper alloy surface, characterized by, The specific steps are as follows: (1) Metal pretreatment: Select copper alloy for cleaning and rust removal, and polish the metal surface to 1500# with sandpaper. Then, use deionized water and anhydrous ethanol for ultrasonic cleaning in sequence, and let it dry for later use. (2) Preparation of MOF-199 ligand solution: Zinc acetate and tricresyl benzene were added to a mixture of equal volumes of water, ethanol and DMF, respectively, and stirred and sonicated to dissolve them completely to obtain MOF-199 ligand solution for later use; The concentration of zinc acetate was 0.05-0.15 mol / L, the concentration of 1,3,5-benzenetricarboxylic acid was 0.5-0.7 mol / L, and the temperature was room temperature. (3) Preparation of low surface energy solution: Add anhydrous calcium chloride and stearic acid to anhydrous ethanol solution, heat and stir at low speed to dissolve, and obtain a low surface energy solution for later use; (4) Preparation of coating: The pretreated copper alloy was placed in MOF-199 ligand solution as the anode, and a graphite sheet of the same size was used as the cathode. The anode was connected to a DC power supply for anodizing for a period of time. Then it was taken out and rinsed with deionized water, dried and placed in a low surface energy solution for a period of time. Then it was taken out and cleaned with anhydrous ethanol and dried. The surface of the copper alloy was coated with a low surface energy MOF-199 superhydrophobic coating.

2. The method for preparing a low surface energy superhydrophobic coating on a copper alloy surface according to claim 1, characterized in that, The rust removal and cleaning steps in step (1) are as follows: the copper alloy is polished by passing it through metallographic sandpaper of 240#, 600#, 1000# and 1500# in sequence.

3. The method for preparing a low surface energy superhydrophobic coating on a copper alloy surface according to claim 1, characterized in that, The copper alloy is selected from C7701 copper alloy, B10 copper alloy, or aluminum brass.

4. The method for preparing a low surface energy superhydrophobic coating on a copper alloy surface according to claim 1, characterized in that, In step (2), the concentration of zinc acetate is 0.1 mol / L, the concentration of 1,3,5-benzenetricarboxylic acid is 0.6 mol / L, and the temperature is room temperature.

5. The method of claim 1, wherein the copper alloy surface is prepared by the steps of: In step (2), the stirring speed is 300-360 rpm and the stirring time is 15 min.

6. The method for preparing a low surface energy superhydrophobic coating on a copper alloy surface according to claim 1, characterized in that, In step (3), the concentration of anhydrous calcium chloride is 0.05-0.15 mol / L, the concentration of stearic acid is 0.1-0.2 mol / L, and the temperature is 40℃.

7. The method for preparing a low surface energy superhydrophobic coating on a copper alloy surface according to claim 6, characterized in that, In step (3), the concentration of anhydrous calcium chloride is 0.1 mol / L and the concentration of stearic acid is 0.1 mol / L.

8. The method for preparing a low surface energy superhydrophobic coating on a copper alloy surface according to claim 1, characterized in that, In step (4), the distance between the two electrodes in the anodic oxidation is 25 mm, the oxidation voltage is 20-40 V, and the oxidation time is 10-30 min; the immersion time in the low surface energy solution is 3-5 h.

9. The method for preparing a low surface energy superhydrophobic coating on a copper alloy surface according to claim 8, characterized in that, In step (4), the oxidation voltage is 30V and the oxidation time is 15min; the immersion time in the low surface energy solution is 4h.

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