Method for preparing superhydrophobic ternary alloy coating, product obtained thereby, and applications thereof

Abstract

The present invention discloses a preparation method of a superhydrophobic ternary alloy coating, which comprises the following steps: in an ice-water mixed bath, stirring and using anodic oxidation to construct a honeycomb porous titanium template with an open type and a structure where pores penetrate through each other on the surface of pure titanium; using the honeycomb porous titanium template as a substrate, adopting a double-pulse electrodeposition method, regulating the current density in two steps, and stirring to obtain a Ni-Co-Zn electrodeposited coating; after artificial aging or natural aging, promoting the growth of a large number of ZnO dendrites and assembling them into a structure similar to the spherical crown of cocklebur, which has superhydrophobicity. The present invention also discloses the application of the coating in a waterproof and self-cleaning PCB circuit board. The present invention can obtain a superhydrophobic surface without secondary low surface energy coating modification, which is fast, convenient, green and environmentally friendly; the prepared Ni-Co-Zn superhydrophobic ternary alloy metal coating has excellent self-repairing, self-cleaning and anti-icing performance, providing inspiration for the research and development of anti-icing surfaces and self-cleaning alloy materials.

Description

Technical Field

[0001] The present invention belongs to the field of superhydrophobic materials, and particularly relates to a preparation method of a superhydrophobic ternary alloy coating, a product obtained thereby, and applications thereof. Background Art

[0002] Superhydrophobic materials have attracted much attention due to their wide application prospects in anti-wetting, anti-icing, self-cleaning, anti-corrosion and other aspects. Common preparation methods include electrochemical method, femtosecond laser, self-assembly method, sol-gel method, etc. With the rapid development of bionic materials, using electrochemical regulation of composition-structure to construct nano-microstructures, and then performing secondary modification with low surface energy coatings to obtain superhydrophobic surfaces has become the main research direction in the future for some time. However, in actual production applications, superhydrophobic surfaces are easily affected by external conditions. For example, under the action of ultraviolet rays, mechanical friction, etc., the hydrophobic substances on their surfaces are degraded or the micro-nano structures are damaged, thereby reducing or losing the superhydrophobic performance. In addition, the low surface energy silanes or perfluorinated organic compounds used in secondary modification will decompose under light or in the natural environment for a certain period of time, with poor weather resistance or their products polluting the environment. Moreover, the production efficiency of low surface energy carbon-fluorine coatings is low, the process is complex, and the equipment cost is high, thus restricting their industrial application. In view of this, it is particularly necessary to develop a superhydrophobic surface with high efficiency, environmental protection and low cost.

[0003] The most typical superhydrophobic surface is the lotus leaf. Many observations have been made by researchers, and it is found that the superhydrophobic performance of the lotus leaf is the result of the synergistic effect of micron-scale papillae structures and wax-like substances. In 2002, domestic scholars such as Jiang Lei et al. showed that there are nano-scale structures under the micron-scale structures of the lotus leaf, revealing that micro-nano geometric structures and wax-like substances are necessary conditions for forming superhydrophobic performance, and they are applied to bionic coatings. A superhydrophobic surface refers to a surface with a static contact angle of the water droplet greater than 150° and a rolling angle (SA) less than 10°. It widely exists in nature, such as superhydrophobic surfaces of rice leaves, rose petals, gecko feet, water strider legs, insect eyes, butterfly wings, beetle back shells, etc. With the performance requirements of spacecraft materials for light weight, high strength, hydrophobic anti-icing and weather resistance, the strength and surface performance of traditional alloys such as Al or Mg can no longer meet the requirements. Preparing key parts such as spacecraft wings with honeycomb porous Ti and endowing it with special surface structures and physical and chemical properties has become the future development trend.

[0004] However, porous titanium exhibits superhydrophilicity and strong oxidizing properties, making it difficult to remove atmospheric pollutants adhering to its surface. In recent years, methods such as using fluorocarbon polymers to reduce the surface free energy of materials have limited effectiveness in improving the anti-fouling and self-cleaning properties of titanium alloy surfaces. Therefore, how to construct a superhydrophobic surface with a suitable geometric topology texture has become the key. Anodic oxidation technology is a mature process for forming nanotube structures on the surface of metals such as titanium or aluminum, which is fast and simple. However, the traditional anodic oxidation process to obtain TiO2 nanotube array structure features has defects such as tube wall shielding effect, large growth stress, and easy peeling, and is not suitable for industrial applications. Considering the excellent physical properties of titanium alloys, how to construct an open and interconnected structure on the surface of titanium alloys, improve the interfacial bonding force between its surface function and the titanium substrate, and extend the service life of the coating is an urgent problem to be solved. Summary of the Invention

[0005] Object of the Invention: In order to overcome the deficiencies in the prior art, the object of the present invention is to provide a preparation method of a superhydrophobic ternary alloy coating that is simple and convenient and does not require secondary modification with a low surface energy coating; another object of the present invention is to provide a superhydrophobic ternary alloy coating with a multi-order component intergrown and symbiotic mixed crystal structure, a cocklebur-like spherical crown texture with multi-tentacle ZnO dendrites, capable of self-repairing, self-cleaning, and anti-icing; still another object of the present invention is to provide an application of the superhydrophobic ternary alloy coating in a waterproof and self-cleaning PCB circuit board.

[0006] Technical Solution: A preparation method of a superhydrophobic ternary alloy coating according to the present invention includes the following steps:

[0007] (1) In an ice-water mixed bath, stir and use anodic oxidation to construct a honeycomb porous titanium template with an open and through-hole structure on the surface of a pure titanium substrate;

[0008] (2) Using the honeycomb porous titanium template as the substrate, adopt a double-pulse electroplating method with a pulse frequency of 1.5 - 2.5 kHz and a positive-negative current duty ratio of 1:3 - 1:5. Regulate the current density in two steps. The initial current density for the first time is 0.25 - 0.3 A / cm 2 , the time is 1100 - 1200 s, the current density for the second time is 0.4 - 0.5 A / cm 2 , the time is 2400 - 2500 s, and the concentration of Zn 2+ in the plating solution is 25 - 100 g / L, stir to obtain a Ni-Co-Zn ternary electroplated coating;

[0009] (3) After artificial aging or natural aging of the Ni-Co-Zn ternary electroplated coating, a superhydrophobic ternary alloy coating is obtained.

[0010] Further, in step (1), the voltage of the anodic oxidation method is 160 - 180 V, and the current at equilibrium decreases to 0.01 - 0.03 A / cm 2 , and the ice - water mixed oxidation solution includes: 360 - 370 g / L of sulfuric acid, 55 - 65 g / L of hydrochloric acid, 10 - 20 g / L of phosphoric acid, and 2 - 4 g / L of glycerol, and the temperature is set at 3 - 5 °C. The pure titanium substrate is stress - relieved annealed in an Ar atmosphere at 440 - 460 °C for 2 - 4 h, then mirror - polished, cleaned with hot alkaline solution, ultrasonically cleaned with deionized water, and dried with nitrogen. The stirring is magnetic stirring with a rotation speed of 300 - 350 rpm.

[0011] Further, in step (2), the plating solution includes: 90 - 95 g / L of nickel sulfate, 20 - 25 g / L of cobalt sulfate, 25 - 100 g / L of zinc sulfate, 50 - 55 g / L of boric acid, 5 - 7 g / L of acetic acid, and 3 - 10 g / L of complexing agent. The pH of the plating solution is 4.0 - 5.0, and the temperature is 30 - 37 °C. The complexing agent is citrate. The stirring rate is 200 - 300 rpm. Among them, when the concentration of zinc sulfate in the plating solution is 50 g / L, the super - hydrophobicity of the alloy coating is the best, with a WCA value as high as 153.2° and an SA lower than 7.8°.

[0012] Further, in step (3), after natural aging for more than 14 days, the surface of the coating turns hydrophobic; after artificial aging at 200 °C, it shows hydrophobicity after only 7 days and reaches super - hydrophobicity after more than 10 days, with a WCA value as high as 153° and an SA lower than 7.8°. At this time, the element contents in the super - hydrophobic ternary alloy coating are: 71.6 - 76.6 wt.% Zn, 5.3 - 8.0 wt.% Ni, 2.1 - 4.6 wt.% Co, and the rest is O. Artificial aging at 200 °C is preferred. After artificial aging at 200 °C, it reaches hydrophobicity after only 4 days of exposure to dry air and reaches super - hydrophobicity after more than 7 days. Artificial aging accelerates the preferential growth of multi - tentacle ZnO dendrites from the Ni - Co - Zn alloy. However, after the aging temperature is higher than 300 °C, some synapses are melted, the cocklebur structure evolves into a hairy - flaky ZnO phase, and a "carbon nanotube" - like columnar crystal structure appears, and the super - hydrophobicity decreases significantly. Compared with natural aging, artificial aging can achieve the transition from hydrophilic to super - hydrophobic in a shorter time because artificial aging can promote the rapid growth of spherical - cap textures.

[0013] A super - hydrophobic ternary alloy coating obtained by the above - mentioned preparation method, including ZnO dendrites, Ni nanocrystals, and Co nanocrystals, has a cocklebur - like spherical - cap structure, with ZnO dendrites as tentacles and Ni nanocrystals or Co nanocrystals as spherical nuclei, and has a self - healing function.

[0014] An application of the above - mentioned super - hydrophobic ternary alloy coating in a waterproof and self - cleaning PCB circuit board.

[0015] Preparation principle: The double-pulse electrodeposition technique is adopted to prepare the mixed crystal with multi-component phase intergrowth by regulating the current density in two steps. Meanwhile, the concentration of Zn in the alloy plating solution is optimized, and the Ni-Co-Zn ternary alloy is electrodeposited on the porous titanium. The nanocrystals grow and pin inside the pores of the porous titanium, significantly improving the interfacial bonding force between the coating and the titanium substrate. In the as-electrodeposited state, the Ni-Co-Zn alloy shows hydrophilicity. However, after natural aging (25 °C) for more than 7 days, the surface of the coating undergoes a reversible transformation and shows hydrophobicity. Under the condition of natural aging, the surface components and texture of the alloy undergo self-assembly evolution, and the nanocrystalline Zn is slowly oxidized into ZnO dendrites with synaptic structures, thus possessing a hydrophobic structure. After artificial aging at 200 °C, a similar Xanthium strumarium spherical crown shape with ZnO as the antenna and nanocrystalline Ni or Co as the spherical shell is rapidly formed. A large number of dendrites have a large specific surface area, which is beneficial to the formation of a saturated airbag effect at the gas-solid interface, realizing a superhydrophobic surface. Measured by the BET method on an ASAP 2020Plus HD88 fully automatic specific surface area and micropore porosity analyzer, the specific surface area is as high as 60-110 m 2+ ² / g. 2

[0016] The electrodeposited Ni-Co-Zn ternary alloy also has self-healing function. After the coating is dry-worn for 15 minutes under a 100 g load and then left standing in dry air for more than 7 days, its superhydrophobic performance and anti-icing performance recover to more than 90% of that before wear. This is mainly because after the synapses of the multi-antenna ZnO dendrites are worn, and after meeting the thermodynamic growth conditions, some of the worn multi-antenna ZnO dendrites are re-oxidized and regenerated from the Ni-Co-Zn alloy, and continue to grow preferentially and finally evolve into the ZnO phase, reconstructing the multi-antenna spherical crown texture growing on the nanocrystalline Ni or Co spherical shell to form a micro-nano multi-scale rough surface, achieving the superhydrophobic surface effect. The superhydrophobic alloy coating prepared by this method has excellent self-cleaning and anti-icing performance, effectively making up for the disadvantages of low surface energy polymers such as fluorocarbon coatings, such as poor weather resistance, easy damage, and poor interfacial bonding with the metal matrix. The method is innovative and the process is fast. At the same time, the efficient self-healing function of the metal coating will significantly improve its service life.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following significant features:

[0018] 1. A superhydrophobic surface can be obtained without secondary modification of a low surface energy coating, which is fast, convenient, green and environmentally friendly;

[0019] ​2. The prepared Ni-Co-Zn superhydrophobic ternary alloy metal coating has excellent self-cleaning and anti-icing properties, effectively making up for the shortcomings of low surface energy polymers such as fluorocarbon coatings, including poor weather resistance, easy damage, and poor interfacial bonding with the metal matrix. Compared with low surface energy silanes or perfluorinated organic compounds used in traditional modification, it has good weather resistance, is not easily decomposed, and significantly improves its service life.

[0020] 3. The obtained honeycomb porous titanium with interconnected pores is hydrophilic as the substrate and has wettability at the interface with the plating solution, which is conducive to the rapid diffusion of metal ions in the alloy plating solution into the pores and the occurrence of pinning growth, significantly improving the interfacial bonding force and the service life of the coating, and facilitating industrial promotion and application.

[0021] 4. The prepared Ni-Co-Zn superhydrophobic ternary alloy metal coating can undergo self-assembly evolution. Whether it is natural aging or artificial aging, after about 7 days, a reversible transformation of hydrophobicity will occur. In this process, artificial aging accelerates the self-assembly evolution process of the phase composition and microstructure on the surface of the alloy layer.

[0022] 5. The prepared Ni-Co-Zn superhydrophobic ternary alloy metal coating has a strong self-repair function. After dry wear with a 100g load for 15 minutes and then standing in dry air for >7 days, its superhydrophobic performance (WCA value) and anti-icing performance are restored to 70% of that before wear; when extended to 14 days, it can be restored to more than 90%. This is because some of the worn multi-tentacle ZnO dendrites are re-oxidized and regenerated from the Ni-Co-Zn alloy, continuously undergoing preferential growth and finally evolving into the ZnO phase, and re-establishing a multi-tentacle spherical crown texture growing on the nanocrystalline Ni or Co spherical shell to achieve a superhydrophobic surface. Description of the Drawings

[0023] Figure 1 It is the SEM image of the honeycomb porous titanium surface obtained under different anodic oxidation DC voltages in the present invention. Among them, a is 140V, b is 160V, and c is 180V.

[0024] Figure 2 It is the test result diagram of the water droplet contact angle WCA of the porous titanium substrate surface obtained under different DC voltages in the present invention.

[0025] Figure 3 It is the FE-SEM image of the texture growth morphology of pulse electrodeposited Ni-Co-Zn under different Zn 2+ concentration conditions. Among them, the Zn 2+ concentration of a is 0g / L, the Zn 2+ concentration of b is 25g / L, the Zn 2+ concentration of c is 50g / L, and the Zn 2+ concentration of d is 100g / L.

[0026] Figure 4 It is a curve graph showing the change rule of the surface wettability of each plating sample under different aging treatments (temperature, time) of the present invention. Among them, the Zn concentration of a is 25 g / L, the Zn concentration of b is 50 g / L, and the Zn concentration of c is 100 g / L; 2+ concentration is 25 g / L, and the Zn concentration of b 2+ concentration is 50 g / L, and the Zn concentration of c 2+ concentration is 100 g / L;

[0027] Figure 5 It is an SEM image of the plating sample of Example 1 of the present invention after aging at 200 °C and being exposed to air for 14 days;

[0028] Figure 6 It is an SEM image of the plating sample of Example 6 of the present invention after natural aging at 25 °C and being exposed to air for 14 days;

[0029] Figure 7 It is an SEM image of the plating sample of Example 7 of the present invention after artificial aging at 100 °C and being exposed to air for 14 days;

[0030] Figure 8 It is an SEM image of the plating sample of Example 8 of the present invention after artificial aging at 300 °C and being exposed to air for 14 days;

[0031] Figure 9 It is an OM image of the surface of pure titanium, porous titanium and plating samples (50 g / L Zn 2+ ) after different aging temperatures, showing the characteristics of delayed icing at -10 °C. Among them, a is pure titanium, b is porous titanium, c is the plating layer obtained in Example 5, d is the plating layer obtained in Example 6, e is the plating layer obtained in Example 7, and f is the plating layer obtained in Example 1;

[0032] Figure 10 It is a curve showing the change relationship between the surface wettability of the plating layer after wear of the present invention and the exposure time in air;

[0033] Figure 11 It is an SEM image of the change in the wear surface morphology of the present invention after dry wear under a 100 g load, artificial aging at 200 °C for 2 h, and exposure to air for different times. Among them, a is after wear (0 days), b is exposed to air for 7 days, c is 14 days, and d is a partial enlarged view of c. Detailed implementation manners

[0034] Example 1

[0035] A preparation method of a superhydrophobic ternary alloy plating layer includes the following steps:

[0036] (1) Prepare an open-type honeycomb porous titanium substrate with interconnected pores:

[0037] The pure titanium substrate was stress-relieved annealed at 450 °C for 2 h in an Ar atmosphere. The pure titanium (TA1) plate was wire-cut into a 90×10×2 mm cuboid titanium sheet, and then mirror-polished, cleaned with hot alkaline solution, ultrasonically cleaned with deionized water for 15 min, and dried with nitrogen. In an ice-water mixed bath, anodic oxidation was carried out in a constant voltage mode of high voltage - low current to reduce the micro-arc oxidation induced by high current, which would cause local pores to be dissolved. The voltage of the anodic oxidation method was 160 V, and the current decreased to 0.01 A / cm at equilibrium. 2 The ice-water mixed oxidation solution included: 360 g / L sulfuric acid, 60 g / L hydrochloric acid, 20 g / L phosphoric acid, and 2 g / L glycerol. The temperature was set at 5 °C, and magnetic stirring at a speed of 300 rpm was assisted during the process to keep the electrolyte uniform, and a honeycomb porous titanium template with an open-type and pore-through structure was constructed on the surface of the pure titanium substrate.

[0038] (2) Electrodeposit a Ni-Co-Zn ternary electrodeposited coating on the honeycomb porous titanium obtained in step (1):

[0039] The porous titanium substrate was activated with 5 wt.% dilute hydrochloric acid for 5 s and then immediately subjected to electrodeposition. The experiment used a double-pulse electrodeposition technique with a pulse frequency of 1.5 kHz, a positive-negative current duty cycle of 1:3, and the current density was set in 2 steps to prepare a mixed crystal structure with multi-component phase intergrowth, which was convenient for the preferential growth of active Zn from the alloy and its oxidation to form multi-tentacle ZnO dendrites. The initial current density was 0.25 A / cm 2 for a duration of 1200 s, and the second current density was 0.45 A / cm 2 for a time of 2400 s. The plating solution included: 94 g / L nickel sulfate, 25 g / L cobalt sulfate, 50 g / L zinc sulfate, 53 g / L boric acid, 5 g / L acetic acid, and 5 g / L complexing agent. The stirring rate was 300 rpm, the pH was controlled at about 4.5, and the temperature was 30 °C.

[0040] (3) Perform aging treatment on the coating obtained in step (2)

[0041] The Ni-Co-Zn ternary electrodeposited coating was subjected to artificial aging treatment at 200 °C and left to stand in dry air for 14 days, and then a superhydrophobic ternary alloy coating was obtained. At this time, the content of each element in the superhydrophobic ternary alloy coating was: 75.8 wt.% Zn, 6.1 wt.% Ni, 3.5 wt.% Co, and the rest was O.

[0042] The superhydrophobic ternary alloy coating obtained by the preparation method of this embodiment includes ZnO dendrites, Ni nanocrystals, and Co nanocrystals, and has a cocklebur-like spherical crown structure. The ZnO dendrites are tentacles, and the Ni nanocrystals or Co nanocrystals are the spherical nuclei, with self-healing function. When the concentration of zinc sulfate in the plating solution is 50 g / L, the superhydrophobicity of the alloy coating is the best, and its WCA value is as high as 153.2°, and the SA is lower than 7.8°.

[0043] The adhesion of the coating was tested by the "cross scribing" method using a cutting tool, and it was found that: there was no obvious peeling of the electrodeposited coating, indicating that the coating had good toughness and strong bonding force with the substrate, significantly improving its service life.

[0044] Application 1

[0045] The coating obtained in Example 1 was applied to the PCB circuit board of 3C electronic products, and a lotus leaf effect was formed on the surface to achieve functions such as waterproofing and self-cleaning. The pulse electrodeposited nano-superhydrophobic alloy coating obtained in Example 1 can be carried out on the surfaces of PCB circuit board substrates such as plastics and ITO glass plates, and has advantages such as strong interfacial bonding force, low stress, and long service life. A nano-layer network for waterproofing, moisture-proofing, and anti-corrosion was formed on the PCB surface. This network consists of multi-tentacle ZnO dendrites with a cocklebur-like spherical crown texture, forming an air cushion effect, and having functions such as superhydrophobicity and self-cleaning. At the same time, compared with traditional fluorocarbon and other high-polymer superhydrophobic coatings that are prone to volatilize toxic odors when heated, the electrodeposited ternary superhydrophobic alloy obtained in Example 1 is green and environmentally friendly and can meet the service in an environment above 200 °C.

[0046] Example 2

[0047] The rest of the steps of this example are the same as those of Example 1, and the only difference is that: in step (1), the voltage of the anodization method is replaced with 140 V.

[0048] Comparative Example 1

[0049] The rest of the steps of this example are the same as those of Example 1, and the only difference is that: in step (1), the voltage of the anodization method is replaced with 180 V.

[0050] Example 3

[0051] The rest of the steps of this example are the same as those of Example 1, and the only difference is that: in step (2), the concentration of zinc sulfate in the plating solution is changed to 25 g / L.

[0052] Example 4

[0053] The rest of the steps of this example are the same as those of Example 1, and the only difference is that: in step (2), the concentration of zinc sulfate in the plating solution is changed to 100 g / L.

[0054] Example 5

[0055] All the other steps of this embodiment are the same as those of Embodiment 1, and the only difference is that in step (3), the artificial aging treatment at 200°C is changed to natural aging treatment (25°C).

[0056] Embodiment 6

[0057] All the other steps of this embodiment are the same as those of Embodiment 1, and the only difference is that in step (3), the artificial aging temperature is reduced from 200°C to 100°C.

[0058] Embodiment 7

[0059] All the other steps of this embodiment are the same as those of Embodiment 1, and the only difference is that in step (3), the artificial aging temperature is increased from 200°C to 300°C.

[0060] Under different voltage conditions, the SEM images of the surface characteristic morphology of honeycomb porous titanium are shown as Figure 1 shown in a-c. Among them, for the film layer prepared under the condition of 160V in Embodiment 1, the pore size is uniform and dense, the pore size is concentrated in the range of 300-400nm, and the static water contact angle WCA of the water droplet is about 35°, showing hydrophilicity, as Figure 2 shown. It is beneficial to the wetting of the surface interface of the subsequent electroplating solution, and is beneficial for the metal ions in the electrolyte to quickly enter the pores of the porous titanium and realize the "pinning" type nanocrystalline growth, improving the interfacial bonding force between the coating and the titanium substrate. For the film layer prepared under the condition of 140V in Comparative Example 1, only a locally irregular porous titanium substrate surface is formed under the condition of 140V, which ultimately leads to a weak interfacial bonding force between the subsequent coating and the titanium substrate, and defects such as easy peeling are likely to occur. For the film layer prepared under the condition of 180V in Embodiment 2, a relatively high DC voltage of 180V is used, resulting in partial dissolution of some of the formed porous texture, as Figure 1 shown in c, forming an introverted, double-wall tube type honeycomb porous titanium structure, resulting in an electric field shielding effect at the pore wall opening during the electrodeposition process. Ultimately, the nanocrystals do not grow outward along the pores, the coating interfacial bonding force is poor, and the electrodeposition efficiency is low.

[0061] For the as-electrodeposited state, the microscopic morphology characteristics of Embodiment 3 are characterized, as Figure 3 shown in a. When the concentration of Zn 2+ is 25g / L, due to the concentration polarization control of the Zn 2+ ion diffusion in the cathode region, the consumed Zn 2+It cannot be replenished in time, which inhibits the preferential growth of Zn. The microstructure is mainly spherical, and the multi-tentacle growth is irregular. Compared with Example 1, the coating surface bonding strength of Example 3 is slightly worse. After the coating adhesion test is carried out by cross scribing with a cutting tool, obvious large pieces fall off at the cross edges and square areas, indicating that the coating has poor toughness under this process condition and shows brittle cracking. After artificial aging at 200 °C and standing in dry air for 14 days, its WCA value is as high as 145° and SA is lower than 9.5°. In the delayed icing experiment on the surface of this specimen, the complete icing time of water droplets is 1275 s, and the ice type is peach-shaped. Compared with Example 1, the WCA value of this specimen is slightly lower, and its hydrophobicity and anti-icing performance are slightly worse.

[0062] As for the as-electrodeposited state, the microscopic morphology characteristics of Example 4 are characterized as follows Figure 3 as shown in 2+ Figure

[0063] Under the process conditions of Example 1, the microscopic morphology of the coating surface is as shown in Figure 3 Figure 2+ c. The structure of the electrodeposited Ni-Co-Zn alloy is dense, and the mixed crystal phases of the three components are embedded and symbiotic, with a grain size of 200 nm. Under different conditions, the WCA, SA and anti-icing time results of the porous titanium substrate and the coating specimens before and after aging are listed in Table 1 below. It can be seen from Table 1 that in the as-electrodeposited state, this coating shows hydrophilicity; after different aging treatments, a reversible hydrophobic transformation occurs on the coating surface. The key factors affecting hydrophobicity are the subsequent aging treatment and the

[0064] Table 1 Comparison of Hydrophobicity and Anti-Icing Properties of Porous Titanium Substrate, Examples 1-7 and Comparative Example 1

[0065]

[0066] Note: The surface of the porous titanium is hydrophilic, and water droplets adsorb on its surface and do not roll off, so SA>90°

[0067] The curve graph of the change law of the surface wettability of each coating specimen under different aging treatment (temperature, time) conditions is as shown in Figure 4As shown in the figure. Analysis shows that: whether it is artificial aging or natural aging, the hydrophobicity of the ternary alloy coating shows an upward trend with the extension of time in dry air. Among them, for the samples after artificial aging, the rising rate is faster. After 7 days, the WCA value > 130°; while natural aging requires 14 days to reach WCA value > 120°, which is mainly attributed to the rate at which the active Zn embedded in the mixed crystal oxidizes into the ZnO phase.

[0068] After the coating of Example 1 was left standing in dry air for 14 days, its WCA value reached as high as 153.2° and the SA was lower than 7.8°, showing superhydrophobicity, as Figure 4 b and Figure 5 shown. This is mainly due to the fact that artificial aging at 200 °C meets the thermodynamic conditions required for its growth. The ZnO dendrites preferentially grow outward on the surface of the Ni crystal embryos, forming ZnO dendrites with multi-antenna textures and a similar cocklebur structure with nanocrystalline Ni or Co as the spherical nuclei, which has a large specific surface area and is conducive to the formation of a saturated airbag effect at the gas-solid interface, promoting the water droplets to make point contact with the sample surface and finally achieving the effect of a superhydrophobic surface.

[0069] As Figure 6 , since Example 5 was not artificially aged, it could not meet the thermodynamic conditions required for the rapid preferential growth of the Zn-rich phase from the Ni-Co-Zn mixed crystal. Only a small amount of active Zn was oxidized into the ZnO phase and appeared in the form of columnar crystals. After the wettability test, the coating surface showed hydrophobic characteristics at this time, with a WCA value of 115° and an SA higher than 11.2°. In the characterization of the delayed icing performance on the sample surface, the complete icing time of the water droplets on the sample surface was 939 s. Compared with the examples, the WCA value of this sample was significantly reduced, and its hydrophobicity and ice inhibition ability were poor.

[0070] As Figure 7 , after Example 6 was artificially aged at 100 °C and then left standing in dry air for 14 days, a papillary structure was formed on the surface of the alloy coating, with a large number of ZnO dendrites and a micro-nano geometric rough surface. Its WCA value was 142° and the complete icing time was 1179 s. Compared with the examples, the WCA value of this sample was slightly lower, but its hydrophobicity and ice inhibition ability were comparable.

[0071] As Figure 8 , after Example 7 was aged at 300 °C, the regular cocklebur spherical crown texture quickly evolved into a hairy flaky ZnO phase at the high temperature of 300 °C. At this temperature, some of the ZnO synaptic structures were melted, and the micro-nano second-order rough structure changed into a first-order micron level, exposing a large number of flat coatings, resulting in a significant decrease in the contact angle. Its WCA value was only 108°, and the complete icing time of the water droplets was 1250 s. Compared with the examples, the superhydrophobicity and anti-icing performance of this sample were significantly reduced.

[0072] On a perspective freezing stage at -10°C, the anti-icing characteristics were studied by comparing the delayed icing time of water droplets and their ice shapes. The results are as Figure 9 shown: The ice shape of the water droplets on the surface of the coating sample prepared from the plating solution containing 50 g / L Zn 2+ is peach-shaped after complete icing, and the required time is up to 1418 s, which is nearly 20 times longer than the icing time of water on the porous titanium substrate, thus showing excellent anti-icing characteristics.

[0073] After dry wear for 15 minutes under a 100 g load, through artificial aging at 200°C for 2 h, and standing in dry air for different times, the changes in WCA and SA on the surface of the coating before and after wear were observed to evaluate its self-repair performance, and the changes in the surface morphology of the wear were observed to judge its self-repair function. Through comparison, it was found that: The WCA and SA values on the surface of the coating after standing for 14 days are basically the same as those before wear and can be restored to more than 90%, thus showing a strong self-repair function, as Figure 10 shown. This is mainly because after the papilla texture of the multi-tentacle ZnO dendrites is worn, the active Zn embedded in the mixed crystal will continue to grow preferentially, so that some of the worn multi-tentacle ZnO dendrites will be re-oxidized and regenerated from the Ni-Co-Zn alloy, and continue to grow preferentially and finally evolve into the ZnO phase, and re-construct a multi-tentacle spherical crown texture growing on the nanocrystalline Ni or Co spherical shell to achieve a superhydrophobic surface. SEM images of the surface morphology change characteristics of the coating after the sample is naturally aged for 0, 7, and 14 days after wear are as Figure 11 shown.

[0074] Example 8

[0075] A preparation method of a superhydrophobic ternary alloy coating, comprising the following steps:

[0076] (1) Prepare an open-type honeycomb porous titanium substrate with interconnected pores:

[0077] The pure titanium substrate is stress-relieved annealed at 440°C in an Ar atmosphere for 4 h. The pure titanium (TA1) plate is wire-cut into a 90×10×2 mm rectangular titanium sheet, and then mirror-polished, cleaned with hot alkali solution, ultrasonically cleaned with deionized water for 15 min, and dried with nitrogen. In an ice-water bath, an anodic oxidation is carried out in a constant voltage mode of high voltage - low current to reduce the local pores dissolved due to the micro-arc oxidation induced by high current. The voltage of the anodic oxidation method is 180 V, and the current is reduced to 0.03 A / cm at equilibrium 2, the ice-water mixed oxidation solution includes: 370 g / L of sulfuric acid, 55 g / L of hydrochloric acid, 10 g / L of phosphoric acid, and 4 g / L of glycerol. The temperature is set at 3°C, and during the process, magnetic stirring at a rotation speed of 350 rpm is used to keep the electrolyte uniform, so as to construct a honeycomb porous titanium template with an open type and a structure where pores are interconnected on the surface of the pure titanium substrate.

[0078] (2) Electro-deposit a Ni-Co-Zn ternary electro-deposited coating on the honeycomb porous titanium obtained in step (1):

[0079] The porous titanium substrate is activated with 5 wt.% dilute hydrochloric acid for 5 s and then immediately subjected to electro-deposition. The experiment uses a double-pulse electro-deposition technique with a pulse frequency of 2.5 kHz, a positive-negative current duty ratio of 1:5, and the current density is set in 2 steps to prepare a mixed crystal structure with multi-component phase intergrowth and symbiosis, which is convenient for preferential growth of active Zn from the alloy and its oxidation to form multi-tentacle ZnO dendrites. The initial current density is 0.3 A / cm 2 , the duration is 1100 s, and the second current density is 0.4 A / cm 2 , and the time is 2500 s. The plating solution includes: 90 g / L of nickel sulfate, 20 g / L of cobalt sulfate, 25 g / L of zinc sulfate, 50 g / L of boric acid, 7 g / L of acetic acid, and 3 g / L of complexing agent. The stirring rate is 200 rpm, the pH is controlled at about 4.0, and the temperature is 37°C.

[0080] (3) Perform aging treatment on the coating obtained in step (2)

[0081] After natural aging of the Ni-Co-Zn ternary electro-deposited coating for 11 days, a superhydrophobic ternary alloy coating is obtained. At this time, the content of each element in the superhydrophobic ternary alloy coating is: 76.6 wt.% Zn, 5.3 wt.% Ni, 4.6 wt.% Co, and the rest is O.

[0082] The superhydrophobic ternary alloy coating obtained by the preparation method of this example includes ZnO dendrites, Ni nanocrystals, and Co nanocrystals, and has a structure similar to a cocklebur spherical crown. The ZnO dendrites are tentacles, and the Ni nanocrystals or Co nanocrystals are spherical nuclei, and it has a self-healing function.

[0083] Example 9

[0084] A preparation method of a superhydrophobic ternary alloy coating includes the following steps:

[0085] (1) Prepare a honeycomb porous titanium substrate with an open type and interconnected pores:

[0086] The pure titanium substrate was stress-relieved annealed at 460 °C for 3 h in an Ar atmosphere. The pure titanium (TA1) plate was wire-cut into a cuboid titanium sheet with dimensions of 90×10×2 mm, and then mirror-polished, cleaned with hot alkaline solution, ultrasonically cleaned with deionized water for 15 min, and dried with nitrogen. In an ice-water mixed bath, anodic oxidation was carried out in a constant voltage mode with high voltage and low current to reduce the micro-arc oxidation induced by high current, which could cause local pores to be dissolved. The voltage of the anodic oxidation method was 170 V, and the current decreased to 0.02 A / cm at equilibrium. 2 The ice-water mixed oxidation solution included: 365 g / L sulfuric acid, 65 g / L hydrochloric acid, 15 g / L phosphoric acid, and 3 g / L glycerol. The temperature was set at 5 °C, and magnetic stirring at a speed of 325 rpm was used during the process to keep the electrolyte uniform, and a honeycomb porous titanium template with an open type and pore-to-pore through structure was constructed on the surface of the pure titanium substrate.

[0087] (2) Electrodeposit a Ni-Co-Zn ternary electrodeposited coating on the honeycomb porous titanium obtained in step (1):

[0088] The porous titanium substrate was activated with 5 wt.% dilute hydrochloric acid for 5 s and then immediately subjected to electrodeposition. The experiment used a double-pulse electrodeposition technique with a pulse frequency of 2 kHz, a positive-to-negative current duty cycle of 1:4, and the current density was set in 2 steps to prepare a mixed crystal structure with multi-component phase intergrowth, which facilitated the preferential growth of active Zn from the alloy and its oxidation to form multi-tentacle ZnO dendrites. The initial current density was 0.28 A / cm 2 , the duration was 1150 s, and the second current density was 0.5 A / cm 2 , and the time was 2450 s. The plating solution included: 95 g / L nickel sulfate, 23 g / L cobalt sulfate, 100 g / L zinc sulfate, 55 g / L boric acid, 6 g / L acetic acid, and 10 g / L complexing agent. The stirring rate was 250 rpm, the pH was controlled at about 5.0, and the temperature was 347 °C.

[0089] (3) Perform aging treatment on the coating obtained in step (2)

[0090] After artificial aging of the Ni-Co-Zn ternary electrodeposited coating at 200 °C for 5 days, a superhydrophobic ternary alloy coating was obtained. At this time, the element contents in the superhydrophobic ternary alloy coating were: 71.6 wt.% Zn, 8.0 wt.% Ni, 2.1 wt.% Co, and the rest was O.

[0091] The superhydrophobic ternary alloy coating obtained by the preparation method of this example includes ZnO dendrites, Ni nanocrystals, and Co nanocrystals, and has a structure similar to a cocklebur spherical crown. The ZnO dendrites are tentacles, and the Ni nanocrystals or Co nanocrystals are spherical nuclei, and it has a self-healing function.

Claims

1. A method for preparing a superhydrophobic ternary alloy coating, characterized in that, It includes the following steps: (1) In an ice-water mixed bath, stir and use anodic oxidation to construct a honeycomb porous titanium template on the surface of a pure titanium substrate; (2)Using a honeycomb porous titanium template as the substrate, the double-pulse electrodeposition method is adopted. The pulse frequency is 1.5 - 2.5 kHz, the duty cycle of the positive and negative currents is 1:3 - 1:5, and the current density is regulated in two steps. The initial current density for the first time is 0.25 - 0.3 A / cm 2 , the time is 1100 - 1200 s, the current density for the second time is 0.4 - 0.5 A / cm 2 , the time is 2400 - 2500 s, stir, and obtain the Ni-Co-Zn ternary electrodeposited coating; (3) After subjecting the Ni-Co-Zn ternary electrodeposited coating to artificial aging at 200 °C and standing in dry air for 14 days, a superhydrophobic ternary alloy coating is obtained; In the step (1), the voltage of the anodic oxidation method is 160V, and the current density is reduced to 0.01 - 0.03 A / cm² at equilibrium. 2 , and the oxidation solution includes: 360 - 370 g / L of sulfuric acid, 55 - 65 g / L of hydrochloric acid, 10 - 20 g / L of phosphoric acid, and 2 - 4 g / L of glycerol, and the temperature is set at 3 - 5 °C; In the step (2), the plating solution includes: nickel sulfate 90-95 g / L, cobalt sulfate 20-25 g / L, zinc sulfate 50 g / L, boric acid 50-55 g / L, acetic acid 5-7 g / L, and complexing agent 3-10 g / L.

2. The preparation method of a superhydrophobic ternary alloy coating according to claim 1, characterized in that: In the step (1), the pure titanium substrate is stress-relieved annealed at 440-460 °C in an Ar atmosphere for 2-4 h, then subjected to mirror polishing, hot alkali solution cleaning, deionized water ultrasonic cleaning, and nitrogen drying.

3. The preparation method of a superhydrophobic ternary alloy coating according to claim 1, characterized in that: In the step (1), the stirring is magnetic stirring, and the rotation speed is 300-350 rpm.

4. The preparation method of a superhydrophobic ternary alloy coating according to claim 1, characterized in that: The pH of the plating solution is 4.0-5.0, and the temperature is 30-37 °C.

5. The preparation method of a superhydrophobic ternary alloy coating according to claim 1, characterized in that: The complexing agent is citrate.

6. The preparation method of a superhydrophobic ternary alloy coating according to claim 1, wherein: In the step (3), the content of each element in the superhydrophobic ternary alloy coating is: 71.6~76.6 wt. % Zn, 5.3~8.0 wt. % Ni, 2.1~4.6 wt. % Co, and the balance is O.

7. The superhydrophobic ternary alloy coating obtained by the preparation method according to any one of claims 1 to 6, characterized in that: It includes ZnO dendrites, Ni nanocrystals and Co nanocrystals, with a cocklebur-like spherical crown structure. The ZnO dendrites are tentacles, and the Ni nanocrystals or Co nanocrystals are spherical nuclei. It has a self-healing function and a specific surface area of 60-110 m 2 / g.

8. Application of a superhydrophobic ternary alloy coating according to claim 7 in a waterproof and self-cleaning PCB circuit board.

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