A super-hydrophobic ni-al metal coating

Abstract

The application relates to a super-hydrophobic Ni-Al metal coating and belongs to the technical field of hydrophobic metal coatings. First, nickel-coated aluminum powder is sprayed on a surface by an atmospheric plasma spraying process to form a Ni-Al metal layer with a micro-nano rough structure, then the surface of the Ni-Al metal layer is subjected to low-surface-energy modification treatment by using a stearic acid ethanol solution, and then drying is carried out to form a super-hydrophobic Ni-Al metal coating on the surface of the workpiece. The Ni-Al metal coating has the characteristics of a large contact angle and a small rolling angle, meets the performance indexes of a super-hydrophobic surface, and has excellent bonding strength with a substrate, so the application has a good application prospect in the super-hydrophobic field.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of super-hydrophobic Ni-Al metal coating, belong to hydrophobic metal coating technical field. BACKGROUND

[0002] Many power facilities are covered with ice in winter, which not only affects normal power supply work, but also causes economic losses. The common deicing methods are mechanical deicing and electric heating deicing, but these two methods greatly consume manpower and material resources, and the reciprocating operation can cause irreversible damage to the structure workpiece. In addition, in the northern salt lake area, the air is humid and contains a lot of salt, the water vapor in the air is liquefied, sublimated or spread and adhered on the metal surface in the form of rime, and at the same time, it can also cause corrosion to the metal. Therefore, a new method of using super-hydrophobic surface to prevent icing has emerged as the times require. The super-hydrophobic surface has low surface energy, and together with its own rough structure, it forms a Cassie wetting model, so it is difficult for water droplets with high surface tension to stay on the super-hydrophobic surface, and therefore it is a good method to prevent icing.

[0003] There are mainly four methods to prepare super-hydrophobic surface: template forming method, phase separation and crystallization method, surface chemical modification, and surface coating modification. The first three methods are relatively complex, and the preparation and replication require high, so it is difficult to truly large-scale industrial application. The surface coating modification method can almost overcome all the shortcomings of the first three methods, and using immersion coating, spraying and other methods can form a large area of uniform super-hydrophobic coating on the material surface.

[0004] At present, when preparing super-hydrophobic coating by thermal spraying process, most of them only consider hardness, wear resistance and corrosion resistance, but the bonding between the coating and the substrate is very important. For example, copper powder, aluminum powder, iron-nickel-chromium alloy powder, nickel-chromium alloy powder, zinc-aluminum alloy powder, tungsten carbide and cobalt agglomerated powder, nickel-based self-fluxing alloy powder and amorphous alloy powder prepared by thermal spraying process, although they have high hardness and good corrosion resistance, but they all have the problems of weak bonding force with the substrate and easy peeling, which leads to the failure of super-hydrophobic coating. SUMMARY

[0005] In view of the shortcomings of the existing super-hydrophobic coating, the present application provides a kind of super-hydrophobic Ni-Al metal coating, nickel-coated aluminum powder forms a specific micro-nano rough structure by atmospheric plasma spraying process, and at the same time, the nickel-coated aluminum powder spontaneously generates a large amount of heat during the spraying process and produces micro-metallurgical bonding with the substrate, so the bonding force is significantly enhanced. In combination with stearic acid low surface energy modification treatment, the micro-nano rough structure formed on the substrate surface realizes the super-hydrophobic function.

[0006] The purpose of the present application is achieved by the following technical solutions.

[0007] A superhydrophobic Ni-Al metal coating is a coating with a micro-nano rough structure on the surface and has undergone low surface energy modification treatment. The surface roughness Ra = 10~14μm, the contact angle CA = 150°~160°, and the roll-off angle SA = 5°~10°.

[0008] The superhydrophobic Ni-Al metal coating was prepared using the following method:

[0009] Nickel-coated aluminum powder is sprayed onto the surface of a workpiece preheated to 100–200°C using an atmospheric plasma spraying process. Compressed air is used to cool the workpiece during the spraying process, resulting in a Ni-Al metal layer with a micro-nano rough structure on the workpiece surface. The workpiece containing the Ni-Al metal layer is then immersed in an ethanol solution of stearic acid, or an ethanol solution of stearic acid is coated onto the surface of the Ni-Al metal layer to completely cover the surface of the Ni-Al metal layer for low surface energy modification treatment. Finally, it is dried to form a superhydrophobic Ni-Al metal coating on the workpiece surface.

[0010] The process parameters for atmospheric plasma spraying are as follows: current 400-500A, voltage 50-65V, working gas flow rate 30-40L / min, auxiliary gas flow rate 1-4L / min, spraying distance 120-150mm, carrier gas flow rate 3-9L / min, powder feed rate 15-25g / min, spraying angle 80-90°, spraying distance 120-150mm, and nickel-coated aluminum powder particle size 45-100μm.

[0011] Furthermore, the surface of the workpiece to be coated is first cleaned with solvent to remove oil, dust and other impurities, and then sandblasted to increase the surface roughness, which is beneficial to improve the adhesion between the workpiece and the coating. The surface roughness of the workpiece is preferably Ra = 3 to 7 μm.

[0012] Furthermore, the mass ratio of Ni to Al in the nickel-coated aluminum powder is 75:25 to 85:15.

[0013] Furthermore, a low surface energy modification treatment was performed on the workpiece containing the Ni-Al metal layer using an ethanol solution of stearic acid with a concentration of 0.05–0.15 mol / L and a temperature of 30–60 °C. Subsequently, the workpiece was dried after standing for 10–60 min (i.e., the time for low surface energy modification treatment of the workpiece containing the Ni-Al metal layer using the ethanol solution of stearic acid).

[0014] Furthermore, drying at 80–200°C for 0.5–6 hours will form a superhydrophobic Ni-Al metal coating on the workpiece surface.

[0015] Furthermore, the thickness of the superhydrophobic Ni-Al metal coating is 0.1–0.25 mm.

[0016] Beneficial effects:

[0017] (1) This invention utilizes atmospheric plasma spraying to coat nickel-coated aluminum powder onto a substrate, forming a rough surface with a corn-stick-shaped micro / nano structure. Stearic acid is then used to modify this rough surface with low surface energy, resulting in a uniform distribution of methyl functional groups that act as a water barrier. This prevents water droplets from wetting the coating upon contact, causing them to disperse into small puddles. This reduces the physical adsorption force of the coating on the water droplets and allows them to rebound under elasticity and surface tension, re-stabilizing on the coating surface in a better aggregated state. Simultaneously, the corn-stick-shaped micro / nano structure, with its small tip and uniform nanostructure distribution, reduces the actual contact area between the water droplets and the coating, making it easier for the droplets to roll on the coating surface. Therefore, the Ni-Al metal coating with a corn-stick-shaped micro / nano structure described in this invention has a large contact angle and a small roll-off angle, meeting the performance requirements of a superhydrophobic surface.

[0018] (2) The present invention uses nickel-coated aluminum powder with a particle size of 45-100μm as the powder to be sprayed. At the same time, the atmospheric plasma spraying process conditions are optimized so that the nickel-coated aluminum powder in this particle size range can be in a molten and semi-molten state at a lower spraying power. At the same time, the exothermic reaction of nickel and aluminum can be fully carried out at a larger spraying distance, so that the nickel-coated aluminum powder can be further melted and reach the substrate surface at high temperature. At this time, the lower half of the large-particle-size nickel-coated aluminum powder is completely melted, while the upper half is in the air and will cool rapidly, leaving some characteristics of the coating powder. The small-particle-size nickel-coated aluminum powder will be completely melted into droplets and splashed on the coating to form a partial submicron structure, thus forming a corn stick-shaped micro-nano composite structure.

[0019] (3) Compared with traditional mechanically mixed Ni / Al powder, the nickel-coated aluminum powder used in this invention is conducive to forming a special corn-stick-shaped micro-nano composite structure, in which the nanostructure can be uniformly distributed on the surface of the micron structure, while the submicron structure and nanostructure distribution obtained by mechanically mixed Ni / Al powder are random and irregular; moreover, nickel-coated aluminum powder can improve the heat release efficiency of nickel and aluminum, allowing the powder to reach the substrate at a higher temperature and form a micro-metallurgical bond with the substrate, thereby ensuring that the prepared Ni-Al metal coating has a better hydrophobic effect and a higher bonding strength with the substrate.

[0020] (4) By selecting nickel-coated aluminum powder with a particle size of 45-100μm as the powder to be sprayed, optimizing the atmospheric plasma spraying process conditions, and combining it with stearic acid low surface energy modification treatment, a Ni-Al metal coating with high bonding strength to the substrate and superhydrophobic function was obtained. Compared with the current Ni-Al metal coating, which is only used as a transition bonding layer in thermal spraying composite coating, the application range of Ni-Al metal coating is broadened, and it has good application prospects in the field of superhydrophobicity. Attached Figure Description

[0021] Figure 1 This is a scanning electron microscope (SEM) image of the surface of the superhydrophobic Ni-Al metal coating prepared in Example 1.

[0022] Figure 2 The image shows the contact angle of the superhydrophobic Ni-Al metal coating prepared in Example 1.

[0023] Figure 3 The image shows the contact angle of the superhydrophobic Ni-Al metal coating prepared in Example 2. Detailed Implementation

[0024] The present invention will be further described below with reference to specific embodiments. Unless otherwise specified, the methods described are conventional methods, and the raw materials described are obtainable from publicly available commercial sources.

[0025] Example 1

[0026] (1) First, clean the surface of the 1060 aluminum alloy workpiece to be sprayed with ethanol (AR, analytical grade). Then, use 20-60 mesh white corundum sand to sandblast the surface of the workpiece to be sprayed. Use compressed air to blow away the white corundum sand particles remaining on the surface of the workpiece so that the surface roughness Ra of the workpiece reaches ~6μm.

[0027] (2) The nickel-coated aluminum powder (Ni 80wt%, Al 20wt%) with a particle size of 45-100μm was placed in an oven at 150℃ and dried. Then the dried nickel-coated aluminum powder was loaded into a powder feeder.

[0028] (3) Clamp the workpiece on the workbench and preheat it to ~150℃; set the spraying travel route program for the robot arm that installs the spray gun, and then use atmospheric plasma spraying technology to spray nickel-coated aluminum powder onto the surface of the workpiece. However, compressed air is used to cool the workpiece during the spraying process. After the spraying is completed, a Ni-Al metal layer with a thickness of 0.1mm and a micro-nano rough structure is formed on the surface of the workpiece.

[0029] The process parameters for atmospheric plasma spraying are as follows: current is 500A, voltage is 60V, spraying angle is 90°, spraying distance is 120mm, working gas (Ar) flow rate is 40L / min, auxiliary gas (H2) flow rate is 3L / min, carrier gas (N2) flow rate is 6L / min, and powder feeding rate is 25g / min.

[0030] (4) Immerse the workpiece containing the Ni-Al metal layer in an ethanol solution of stearic acid at a temperature of 50°C and a concentration of 0.14 mol / L for 10 min, and then put the workpiece in an oven at 80°C to dry for 30 min, so that a superhydrophobic Ni-Al metal coating is formed on the surface of the workpiece.

[0031] The morphology of the prepared superhydrophobic Ni-Al metal coating was characterized from... Figure 1 The SEM images show that the coating surface is uniformly distributed with micron-sized structures, while nanoparticles fill the gaps between the micron-sized structures or are located on their surface. The nanoparticles and micron-sized structures together form a corn-stick-shaped micro-nano rough structure.

[0032] Using a CA500 contact angle meter, the contact angle CA of the prepared superhydrophobic Ni-Al metal coating was measured to be 156°, indicating that the coating possesses superhydrophobic properties. Figure 2 As shown.

[0033] A 2 μL water droplet was rolled 1 mm on the surface of the prepared superhydrophobic Ni-Al metal coating, and its rolling angle SA = 8.160° was measured.

[0034] The surface of the Ni-Al metal layer prepared in step (3) was tested using a roughness tester. Five different locations were selected for testing, and each location was tested three times and the average value was taken. The surface roughness Ra was measured to be 10-14 μm.

[0035] Example 2

[0036] (1) First, clean the surface of the 1060 aluminum alloy workpiece to be sprayed with ethanol (AR, analytical grade). Then, use 20-60 mesh white corundum sand to sandblast the surface of the workpiece to be sprayed. Use compressed air to blow away the white corundum sand particles remaining on the surface of the workpiece so that the surface roughness Ra of the workpiece reaches ~6μm.

[0037] (2) The nickel-coated aluminum powder (Ni 80wt%, Al 20wt%) with a particle size of 45-100μm was placed in an oven at 150℃ and dried. Then the dried nickel-coated aluminum powder was loaded into a powder feeder.

[0038] (3) Clamp the workpiece on the workbench and preheat it to ~150℃; set the spraying travel route program for the robot arm that installs the spray gun, and then use atmospheric plasma spraying technology to spray nickel-coated aluminum powder onto the surface of the workpiece. However, compressed air is used to cool the workpiece during the spraying process. After the spraying is completed, a Ni-Al metal layer with a thickness of 0.16mm and a micro-nano rough structure is formed on the surface of the workpiece.

[0039] The process parameters for atmospheric plasma spraying are as follows: current is 480A, voltage is 55V, spraying angle is 90°, spraying distance is 120mm, working gas (Ar) flow rate is 32L / min, auxiliary gas (H2) flow rate is 1.5L / min, carrier gas (N2) flow rate is 6L / min, and powder feeding rate is 25g / min.

[0040] (4) Immerse the workpiece containing the Ni-Al metal layer in an ethanol solution of stearic acid at a temperature of 50°C and a concentration of 0.14 mol / L for 10 min, and then put the workpiece in an oven at 80°C to dry for 30 min, so that a superhydrophobic Ni-Al metal coating is formed on the surface of the workpiece.

[0041] The morphology of the prepared superhydrophobic Ni-Al metal coating was characterized. According to the characterization results, there is a corn-stick-shaped micro-nano rough structure on the surface of the coating. This micro-nano rough structure is composed of micro-structures and nanoparticles filling the gaps between the micro-structures and deposited on the surface of the micro-structures.

[0042] The contact angle CA of the prepared superhydrophobic Ni-Al metal coating was measured to be 150° using a CA500 contact angle meter, indicating that the coating possesses superhydrophobic properties. Figure 3 As shown.

[0043] A 2 μL water droplet was rolled 1 mm on the surface of the prepared superhydrophobic Ni-Al metal coating, and its rolling angle SA = 8.920° was measured.

[0044] The surface of the Ni-Al metal layer prepared in step (3) was tested using a roughness tester. Five different locations were selected for testing, and each location was tested three times and the average value was taken. The surface roughness Ra was measured to be 10-14 μm.

[0045] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A superhydrophobic Ni-Al metal coating, characterized in that: Surface roughness Ra = 10~14 μm, contact angle CA = 150° o ~160 o Roll angle SA=5 o ~10 o Specifically, it is prepared using the following method: Nickel-clad aluminum powder is sprayed onto a preheated surface (100-200°C) using atmospheric plasma spraying. o For workpiece C, compressed air is used to cool the workpiece during the spraying process, forming a Ni-Al metal layer with a corn-stick-shaped micro-nano rough structure on the workpiece surface; then the workpiece containing the Ni-Al metal layer is immersed in an ethanol solution of stearic acid or the surface of the Ni-Al metal layer is coated with an ethanol solution of stearic acid and completely covered to perform low surface energy modification treatment, and finally dried, thus forming a superhydrophobic Ni-Al metal coating on the workpiece surface. The process parameters for atmospheric plasma spraying are as follows: current 400~500 A, voltage 50~65 V, working gas flow rate 30~40 L / min, auxiliary gas flow rate 1~4 L / min, spraying distance 120~150 mm, carrier gas flow rate 3~9 L / min, powder feed rate 15~25 g / min, and spraying angle 80~90 degrees Celsius. o The spraying distance is 120~150 mm, and the particle size of the nickel-coated aluminum powder is 45~100 μm.

2. The superhydrophobic Ni-Al metal coating according to claim 1, characterized in that: The surface of the workpiece to be coated is first cleaned with solvent to remove oil, dust and impurities, and then sandblasted to increase the surface roughness.

3. The superhydrophobic Ni-Al metal coating according to claim 2, characterized in that: The surface roughness of the workpiece is Ra = 3~7 μm.

4. The superhydrophobic Ni-Al metal coating according to claim 1, characterized in that: The mass ratio of Ni to Al in nickel-coated aluminum powder is 75:25 to 85:

15.

5. A superhydrophobic Ni-Al metal coating according to claim 1, characterized in that: A concentration of 0.05–0.15 mol / L and a temperature of 30–60 °C were used. o The workpiece containing the Ni-Al metal layer was subjected to low surface energy modification treatment with an ethanol solution of stearic acid of C, and then dried after standing for 10 to 60 minutes.

6. A superhydrophobic Ni-Al metal coating according to claim 1, characterized in that: Set at 80~200 o Drying at C for 0.5~6 h will form a superhydrophobic Ni-Al metal coating on the workpiece surface.

7. A superhydrophobic Ni-Al metal coating according to any one of claims 1 to 6, characterized in that: The thickness of the superhydrophobic Ni-Al metal coating is 0.1~0.25 mm.

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