Super-hydrophobic copper surface for stator water-cooling copper pipe and preparation method of super-hydrophobic copper surface

Abstract

The invention relates to a preparation method of a super-hydrophobic copper surface for a stator water-cooling copper pipe. The method comprises the steps that the surface of the water-cooled copper pipe is cleaned through alkaline cleaning liquid, and the surface of the water-cooled copper pipe comprises a copper oxide layer; carrying out acid pickling treatment on the cleaned copper oxide layer through an acidic cleaning solution so as to form a surface layer with a nano porous structure on the copper oxide layer; and the surface layer is placed in a stearic acid solution to be soaked, so that the super-hydrophobic copper surface is formed on the surface layer. Based on the method, the method can adapt to the shape of a long and thin pipeline, the influence of oxide deposition can be effectively overcome, and a super-hydrophobic layer is formed on the inner surface of the water-cooled copper pipe.

Description

Technical Field

[0001] The present application relates to the technical field of metal material surface treatment, and in particular to a super-hydrophobic copper surface for a stator water-cooling copper tube and a preparation method thereof. Background Art

[0002] When the generator is running, the air-core copper coil, iron core and end guard ring will generate heat due to the magnetic induction current, and the heat will increase with the increase of output power, so it needs to be dissipated in time. Water cooling is the main cooling method because of its high efficiency, but the conductivity and corrosiveness of water bring significant problems. In long-term use, the dissolved oxygen, CO2 and low pH value in the water cause corrosion products to deposit in the copper tube, forming oxide layers such as copper oxide, resulting in reduced heat exchange efficiency and gradually reducing the inner diameter of the copper tube, causing a decrease in water flow. In severe cases, it may even cause water flow blockage and cause major accidents.

[0003] Although the generator is regularly chemically cleaned to maintain the cooling effect, the metal surface after pickling is very easy to oxidize again, so that the copper tube is still covered with oxides most of the time. Long-term oxidative corrosion causes copper oxide and cuprous oxide to adhere to the inner surface of the tube, and the extremely small cross-section further aggravates the decline in heat transfer efficiency. At present, existing super-hydrophobic surface preparation technologies such as self-assembly, etching and electrochemical deposition are difficult to apply to small-section long copper tubes, and cannot effectively treat surfaces covered with oxides. Summary of the invention

[0004] The embodiments of the present invention provide a super-hydrophobic copper surface for a stator water-cooling copper tube and a preparation method thereof, which at least solves the problem that the super-hydrophobic surface preparation method in the related art is difficult to apply to long copper tubes with small cross-sections and cannot effectively treat surfaces covered by oxides.

[0005] According to a first aspect of an embodiment of the present invention, there is provided a method for preparing a super-hydrophobic copper surface for a stator water-cooling copper tube, comprising:

[0006] Cleaning the surface of the water-cooled copper tube using an alkaline cleaning solution, wherein the surface of the water-cooled copper tube includes a copper oxide layer;

[0007] Performing an acid wash treatment on the cleaned copper oxide layer with an acid wash solution to form a surface layer having a nanoporous structure on the copper oxide layer;

[0008] The surface layer is placed in a stearic acid solution for immersion treatment to form a super-hydrophobic copper surface on the surface layer.

[0009] According to a second aspect of an embodiment of the present invention, a super hydrophobic copper surface is provided. The super hydrophobic copper surface is prepared according to the method described in the first aspect.

[0010] Beneficial effects of the embodiments of the present invention:

[0011] The super-hydrophobic copper surface preparation method for stator water-cooled copper tube provided in the embodiment of the present invention forms a nanoporous structure on the copper oxide layer through alkaline cleaning and pickling steps, so that stearic acid molecules can be stably attached to the porous surface to form a super-hydrophobic coating, thereby effectively overcoming the influence of oxide deposition, so that super-hydrophobic properties are successfully applied to water-cooled copper tubes in long-term service. Through the periodic use of alkaline cleaning solution and acid cleaning solution, the cleaning and pretreatment of copper tubes are realized without adding additional complex equipment and expensive drugs, simplifying the process steps. In addition, by forming a super-hydrophobic layer on the inner surface of the water-cooled copper tube, the heat exchange efficiency can be improved, and the possibility of oxide deposition is reduced, thereby effectively extending the service life of the copper tube and reducing the cleaning frequency. Finally, since there is no need to use traditional physical processing methods, its cleaning and pickling steps can be used for large length, narrow cross-sectional size copper tube surface modification. The nanoporous structure prepared on the basis of chemical cleaning can fully cover and adapt to the long and thin pipeline shape.

[0012] The details of one or more embodiments of the invention are set forth in the following drawings and description so that other features, objects, and advantages of the invention are more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other embodiments can be obtained based on these drawings without creative work.

[0014] Figure 1 A flow chart of a method for preparing a super-hydrophobic copper surface for a stator water-cooling copper tube provided by an exemplary embodiment of the present invention.

[0015] Figure 2 A schematic diagram of a super-hydrophobic surface of a nanoporous structure provided by an exemplary embodiment of the present invention.

[0016] Figure 3 A schematic diagram of another super-hydrophobic surface of a nanoporous structure provided by an exemplary embodiment of the present invention.

[0017] Figure 4 A schematic diagram of a wetting angle test result provided by an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0018] Embodiments of the present embodiment will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present embodiment are shown in the accompanying drawings, it should be understood that the present embodiment can be implemented in various forms and should not be construed as being limited to the embodiments set forth herein, which are instead provided for a more thorough and complete understanding of the present embodiment. It should be understood that the drawings and embodiments of the present embodiment are only for exemplary purposes and are not intended to limit the scope of protection of the present embodiment.

[0019] Due to the existing super-hydrophobic surface preparation technology such as self-assembly, etching and electrochemical deposition, it is difficult to apply to long copper tubes with small cross-sections, and the surface covered by oxide cannot be effectively treated. In order to solve the problems existing in the prior art, the preparation of the super-hydrophobic layer is more suitable for copper tubes with long and small cross-sections, and its heat exchange efficiency and corrosion resistance are improved. The present invention provides a super-hydrophobic copper surface preparation method for stator water-cooled copper tubes.

[0020] Figure 1 A flow chart of a method for preparing a super-hydrophobic copper surface for a stator water-cooling copper tube provided by an exemplary embodiment of the present invention. Figure 1 As shown, the method includes the following steps.

[0021] Step S101, cleaning the surface of the water-cooled copper tube with an alkaline cleaning solution, wherein the surface of the water-cooled copper tube includes a copper oxide layer.

[0022] Step S102 , performing an acid wash treatment on the cleaned copper oxide layer using an acid wash solution to form a surface layer having a nanoporous structure on the copper oxide layer.

[0023] Step S103, placing the surface layer in a stearic acid solution for immersion treatment to form a super hydrophobic copper surface on the surface layer.

[0024] Firstly, the surface of the water-cooled copper tube is cleaned by an alkaline cleaning solution, wherein the surface of the water-cooled copper tube includes a copper oxide layer.

[0025] In the embodiment of the present invention, the oily impurities and organic matter on the inner surface of the water-cooled copper tube can be removed by using an alkaline cleaning liquid. In practical applications, the above-mentioned oily impurities and organic matter and other pollutants are often adsorbed on the surface of the copper tube, affecting the subsequent pickling effect, and therefore need to be removed first.

[0026] In this embodiment, the alkaline cleaning solution may include sodium phosphate solution, sodium hydroxide solution, sodium carbonate solution, sodium bicarbonate solution, sodium tripolyphosphate solution, etc.

[0027] Among them, sodium phosphate has a chelating effect on grease and some metal ions, which can effectively decompose and remove grease and scale. It can form stable complexes with calcium, magnesium and other ions in water, thereby preventing these ions from forming precipitation during the cleaning process. Sodium hydroxide can effectively remove stubborn grease and organic dirt. Its high alkalinity can accelerate the saponification of grease, which can further improve the cleaning effect. Sodium carbonate is a milder alkaline cleaning agent that has a good cleaning effect on grease and organic matter and is relatively safe. It can be used with sodium phosphate to enhance the comprehensive decontamination ability of alkaline cleaning fluid. Sodium bicarbonate, as an auxiliary ingredient, can be used in conjunction with other alkaline agents to help remove slight oxides and loose dirt, while alleviating the corrosiveness of stronger alkalis. Sodium tripolyphosphate has a dispersing effect, which can prevent oily substances and organic matter from reattaching to the surface of copper pipes and help remove impurities that are difficult to dissolve.

[0028] In practical applications, the various components in the alkaline cleaning solution can be used alone or in combination to adjust the alkalinity strength of the cleaning solution, the cleaning effect and the protective effect on the copper substrate.

[0029] Taking the alkaline cleaning liquid as sodium phosphate solution as an example, the sodium phosphate solution can be composed of 1%-5% sodium phosphate solution. When the surface of the water-cooled copper tube is cleaned by the sodium phosphate solution, the system ambient temperature can be maintained at 50°C to 60°C. Specifically, the temperature is set at 50°C to 60°C, which can enhance the decontamination ability of the cleaning liquid and enable oily impurities and organic matter to dissolve and fall off faster.

[0030] In an optional embodiment, when the surface of the water-cooled copper tube is cleaned by an alkaline cleaning liquid, the alkaline cleaning liquid can be injected into the water-cooled copper tube system, and the water flow direction of the alkaline cleaning liquid can be switched based on a first preset time interval to perform forward and reverse circulation cleaning on the surface of the water-cooled copper tube.

[0031] During the cleaning process, forward and reverse circulation cleaning can be achieved by periodically switching the water flow direction of the cleaning solution. Based on the forward and reverse circulation cleaning method, the flushing effect of the solution can be improved and the uniformity of cleaning can be increased, especially for long and narrow copper tube sections, which can effectively avoid the problem of incomplete cleaning due to stagnation of solution in some areas. Optionally, a small amount of surfactant can be added to the sodium phosphate solution to further increase the permeability and wettability of the cleaning solution, making it easier to contact the oxide layer on the inner wall of the copper tube.

[0032] In practical applications, during the cleaning process, the first preset time interval may include 0.5 hours to 1 hour. In order to ensure that the cleaning liquid can effectively cover and contact the entire inner wall surface of the pipeline, the inlet and outlet of the stator coil cooling water may be switched every 0.5 hours to 1 hour to reverse the water flow direction.

[0033] In an optional embodiment, after the surface of the water-cooled copper tube is cleaned with an alkaline cleaning solution, the surface of the water-cooled copper tube may also be cleaned with deionized water to remove the alkaline cleaning solution remaining on the surface of the water-cooled copper tube.

[0034] In this embodiment, after the alkaline cleaning is completed, the copper tube is rinsed with deionized water. The deionized water cleaning step is intended to remove residual components in the alkaline cleaning solution to prevent them from affecting the activity of the acid cleaning solution in the subsequent pickling process. Deionized water does not contain minerals and impurities, so it can thoroughly clean the surface of the copper tube without introducing new ionic substances, ensuring the purity of the surface chemical environment in preparation for pickling.

[0035] Optionally, in demanding applications, multiple deionized water rinses can be used to ensure that the cleaning agent is completely removed and further reduce the possibility of residual alkaline substances. In addition, a low-temperature drying step can be added after the deionized water rinse to avoid water droplets remaining on the inner surface of the copper tube and ensure uniform contact with the cleaning solution during pickling.

[0036] After the deionized water rinse is completed, the cleaned copper oxide layer can be pickled with an acidic cleaning solution to form a surface layer with a nanoporous structure on the copper oxide layer.

[0037] In this embodiment, after the deionized water rinse, an acid wash treatment is performed to further remove the relatively stubborn copper oxide layer and form a nanoporous structure on the surface.

[0038] The acidic cleaning solution in this embodiment may include a mixed solution of citric acid, formic acid and ethylenediaminetetraacetic acid, with a concentration of 2% to 4%, and a cleaning temperature of 40°C to 70°C. Among them, citric acid and formic acid are organic acids that can gently dissolve oxides on the copper surface, while ethylenediaminetetraacetic acid has good complexing ability, which can effectively remove copper ions and prevent them from being redeposited on the inner wall of the copper tube. In addition, the control of the pickling temperature can optimize the formation of nanoporous structures, which helps to provide structural support with high adhesion for subsequent super-hydrophobic coatings.

[0039] In an optional embodiment, an acidic cleaning liquid is injected into the water-cooled copper pipe system, and the water flow direction is switched based on a second preset time interval, and the pickling liquid is ensured to be evenly distributed throughout the copper pipe through forward and reverse cycle pickling, and the copper oxide layer is completely removed, while a surface nanoporous structure is generated. The nanoporous structure increases the surface area, which is conducive to the stable attachment of the subsequent hydrophobic layer. Optionally, the second preset time interval may include 20 minutes to 30 minutes.

[0040] In an optional embodiment, ultrasonic vibration can be used to assist pickling during the pickling stage. For copper tubes with thicker oxide layers, ultrasonic waves can increase the diffusivity and permeability of the pickling solution and accelerate the stripping of the oxide.

[0041] After the nanoporous structure is formed, the surface layer can be placed in a stearic acid solution for immersion treatment to form a super-hydrophobic copper surface on the surface layer.

[0042] In this embodiment, the stearic acid solution can be a mixed solution of stearic acid and ethanol, wherein the mass fraction of stearic acid is 1.5% to 2%. Ethanol as a solvent can accelerate the attachment of stearic acid to the copper surface, and stearic acid molecules have a long chain structure and can form a stable hydrophobic layer with the nanoporous structure.

[0043] Optionally, the concentration of stearic acid can be appropriately adjusted according to the use environment of the copper tube. For example, in a high humidity environment, the concentration of stearic acid can be appropriately increased to enhance the durability of the hydrophobic layer. In addition, stearic acid can also be mixed with other hydrophobic organic acids (such as myristic acid) to enhance the corrosion resistance and stability of the hydrophobic layer.

[0044] In an optional embodiment, during the soaking treatment, the soaking time can be 120 minutes. After a long soaking period, the stearic acid molecules can fully penetrate into the nanoporous structure, ensuring the uniformity and stability of the hydrophobic layer and forming a durable super-hydrophobic surface. The super-hydrophobic surface of the nanoporous structure in this embodiment is as follows Figure 2 and Figure 3 shown.

[0045] In an optional embodiment, after the stearic acid immersion treatment, a low-temperature heat treatment (such as 60°C to 80°C) can be performed to help the stearic acid molecules adhere more firmly to the surface of the copper tube, further improving the stability and durability of the hydrophobic layer.

[0046] The preparation method provided by the embodiment of the present invention forms a stable nanoporous structure on the inner wall of the copper tube by three steps of cleaning, pickling and soaking, and further forms a super-hydrophobic coating by the treatment of stearic acid solution. This super-hydrophobic layer can effectively block the direct contact between oxidizing substances in water and the copper tube, reduce the deposition of oxides, and extend the service life of the copper tube. In addition, due to the use of chemical solution treatment method, not only the process is simple, and no additional complex equipment is required, it is suitable for the inner surface treatment of large quantities of long-sized copper tubes, and has good application prospects.

[0047] This method removes the oxide layer on the surface of the copper tube through the dual effects of alkaline cleaning and acid cleaning, providing a suitable attachment structure for stearic acid molecules. At the same time, extended solutions such as periodic forward and reverse cleaning, ultrasonic assistance, and heat treatment further enhance the practicality of the solution, allowing the preparation method to maintain excellent performance in a variety of working conditions.

[0048] In the following, in conjunction with specific embodiments, a method for preparing a super-hydrophobic copper surface for a stator water-cooling copper tube provided by an embodiment of the present invention is described in detail.

[0049] Example 1

[0050] In this embodiment, the copper oxide layer of the corrosion product on the surface of the stator water-cooling copper tube is used as the treatment substrate, and the steps are as follows:

[0051] Alkaline cleaning: Place the water-cooled copper tube to be treated in a 1% sodium phosphate alkaline solution at a temperature of 60°C to remove oily impurities in the system.

[0052] Pickling: Use a 2% citric acid solution to pickle the substrate after alkaline cleaning. During the pickling process, the system temperature is maintained at 50-60°C and the cleaning time is 20 minutes to form a surface layer with a nanoporous structure on the surface of the substrate.

[0053] Super hydrophobic coating treatment: The acid-washed substrate was immersed in a stearic acid solution to form a super hydrophobic layer on the surface. After treatment, the sample was tested for a wetting angle, and the wetting angle of the surface was measured to be 174.3°, proving that the surface has good super hydrophobicity. The schematic diagram of the wetting angle test results is attached. Figure 4 shown.

[0054] Example 2

[0055] In this embodiment, the preparation of a super-hydrophobic surface is achieved on a copper oxide layer substrate through improved processing steps, the steps are as follows:

[0056] Deionized water rinsing: Rinse the copper oxide layer on the surface of the stator water-cooled copper tube in deionized water to remove dust and light dirt on the surface and provide a clean surface for subsequent pickling.

[0057] Acid washing: the substrate after being rinsed with deionized water is immersed in a citric acid solution with a mass fraction of 4%, the temperature is maintained at 60° C., and the treatment time is 30 minutes.

[0058] Super-hydrophobic coating treatment: The acid-washed substrate was immersed in a 2% by mass stearic acid solution for 2 hours at a temperature of 0°C.

[0059] Example 3

[0060] In this embodiment, the processing steps are similar to those in Example 2, but the temperature during the super-hydrophobic coating treatment is adjusted. The specific steps are as follows:

[0061] Deionized water flushing: Using the copper oxide layer, a corrosion product on the surface of the stator water-cooling copper tube, as the base, deionized water is used to flush and remove dust and impurities on the surface.

[0062] Acid washing: the substrate rinsed with deionized water is immersed in a citric acid solution with a mass fraction of 4%, the temperature is set at 60° C., and the treatment time is 20 minutes to form a nanoporous structure on the surface of the substrate.

[0063] Super hydrophobic coating treatment: The substrate treated with super hydrophobic coating is placed in a 2% by mass stearic acid solution at 20°C for 2 hours. Properly increasing the temperature can promote the adsorption of stearic acid and make the hydrophobic layer more uniform and stable.

[0064] Performance Testing

[0065] The static contact angle test was conducted on the samples of Examples 1 to 3 and the comparative samples. The static contact angle of the samples was tested using a JC-2000C1 contact angle measuring instrument. The test results are shown in Table 1:

[0066] Table 1 Static contact angle test results

[0067] Static contact angle Example 1 174.3° Example 2 172.6° Example 3 172.4°

[0068] The experimental results show that the super-hydrophobic copper surface prepared by the method of the present invention has a high static contact angle, which verifies its excellent hydrophobic performance.

[0069] It should be noted that the term "including" and its variations used in the embodiments of the present invention are open inclusions, that is, "including but not limited to". The term "based on" means "based at least in part on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments". The modifications of "one" and "multiple" mentioned in the embodiments of the present invention are illustrative rather than restrictive. Those skilled in the art should understand that unless the context clearly indicates otherwise, it should be understood as "one or more".

[0070] The user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in the embodiments of the present invention are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant laws, regulations and standards of relevant countries and regions, and provide corresponding operation entrances for users to choose to authorize or refuse.

[0071] The various steps described in the method implementation methods provided in the embodiments of the present invention may be performed in different orders and / or in parallel. In addition, the method implementation methods may include additional steps and / or omit the steps shown. The scope of protection of the present invention is not limited in this respect.

[0072] The term "embodiment" in this specification refers to specific features, structures or characteristics described in conjunction with the embodiment that can be included in at least one embodiment of the present invention. The appearance of this phrase in various places in the specification does not necessarily mean the same embodiment, nor does it mean that it is mutually exclusive with other embodiments and is independent or optional. The various embodiments in this specification are described in a related manner, and the same or similar parts between the various embodiments refer to each other. In particular, for the device, equipment, and system embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts refer to the partial description of the method embodiment.

[0073] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of patent protection. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a super-hydrophobic copper surface for a stator water-cooling copper tube, comprising: Cleaning the surface of the water-cooled copper tube using an alkaline cleaning solution, wherein the surface of the water-cooled copper tube includes a copper oxide layer; Performing an acid wash treatment on the cleaned copper oxide layer with an acid wash solution to form a surface layer having a nanoporous structure on the copper oxide layer; The surface layer is placed in a stearic acid solution for immersion treatment to form a super-hydrophobic copper surface on the surface layer.

2. The method according to claim 1, characterized in that The alkaline cleaning solution includes a sodium phosphate solution; the concentration of the alkaline cleaning solution is 1% to 5%, and the temperature of the alkaline cleaning solution is 50° C. to 60° C.

3. The method according to claim 1, characterized in that The cleaning process of the surface of the water-cooled copper tube by using an alkaline cleaning liquid comprises: The alkaline cleaning liquid is injected into the water-cooled copper pipe system, and the water flow direction of the alkaline cleaning liquid is switched based on a first preset time interval to perform forward and reverse circulation cleaning on the surface of the water-cooled copper pipe.

4. The method according to claim 1, characterized in that: After the surface of the water-cooled copper tube is cleaned by the alkaline cleaning solution, the method further comprises: The surface of the water-cooled copper tube is cleaned with deionized water to remove the alkaline cleaning liquid remaining on the surface of the water-cooled copper tube.

5. The method according to claim 1, characterized in that: The acid cleaning solution includes citric acid solution, formic acid solution and ethylenediaminetetraacetic acid solution; the concentration of the acid cleaning solution is 2% to 4%, and the temperature of the acid cleaning solution is 40° C. to 70° C.

6. The method according to claim 1, characterized in that The step of performing an acid wash treatment on the cleaned copper oxide layer by using an acid wash solution to form a surface layer having a nanoporous structure on the copper oxide layer comprises: The acid cleaning liquid is injected into the water-cooled copper pipe system, and the water flow direction of the acid cleaning liquid is switched based on a second preset time interval to perform forward and reverse circulation cleaning on the copper oxide layer.

7. The method according to claim 1, characterized in that The stearic acid solution is a mixed solution of stearic acid and ethanol, wherein the mass fraction of stearic acid in the stearic acid solution is 1.5% to 2%.

8. The method according to claim 1, characterized in that The time for immersing the surface layer in the stearic acid solution is 120 minutes.

9. A super hydrophobic copper surface, characterized in that The super hydrophobic copper surface is prepared according to the method described in any one of claims 1 to 8.

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