Super-hydrophobic self-cleaning aluminum alloy coating and preparation method thereof

Abstract

The invention discloses a super-hydrophobic self-cleaning aluminum alloy coating and a preparation method thereof, and belongs to the technical field of metal surface treatment.The preparation method comprises the following steps that S1, an aluminum alloy substrate is pretreated; s2, mixing TEOS, absolute ethyl alcohol and diluted hydrochloric acid in a beaker, and adding PFOTES to obtain sol; s3, mixing the SiO2 powder, the TiO2 powder, PVP (Polyvinyl Pyrrolidone) and deionized water, and carrying out spray granulation, so as to obtain SiO2-TiO2 composite powder; s4, the SiO2-TiO2 composite powder, absolute ethyl alcohol and PFOTES are mixed, and composite powder slurry is obtained; s5, spraying the sol on the surface of an aluminum alloy substrate, and drying to obtain an aluminum alloy basic coating; s6, the composite powder slurry is sprayed on the aluminum alloy coating base layer, and after drying, the aluminum alloy composite coating is obtained; and S7, the aluminum alloy substrate is placed in a drying oven for heat treatment, and the super-hydrophobic self-cleaning aluminum alloy coating is obtained. The coating system disclosed by the invention is stable and can effectively realize self-cleaning.

Description

Technical Field

[0001] The invention belongs to the technical field of metal surface treatment, and particularly relates to a super-hydrophobic self-cleaning aluminum alloy coating and a preparation method thereof. Background Art

[0002] The super-hydrophobicity of aluminum alloy refers to the ability of the aluminum alloy surface to repel water droplets through specific surface treatment technology. Water droplets are difficult to wet on its surface and show the characteristics of high contact angle (generally greater than 150°) and low rolling angle (generally less than 10°). This super-hydrophobic surface can significantly reduce the adhesion between liquid and solid, making it easy for water droplets to roll and slide on the surface, thereby achieving a self-cleaning effect. The self-cleaning property of aluminum alloy refers to the ability of the aluminum alloy surface to automatically remove or reduce surface pollutants and dirt without human intervention; this self-cleaning property is usually achieved through two mechanisms: one is that the air film layer formed on the super-hydrophobic surface can prevent pollutants from adhering to the surface, and the other is that the special microstructure of the surface can cause pollutants to automatically fall off under the action of natural forces such as wind and rain.

[0003] Aluminum alloy is the most widely used type of non-ferrous metal structural material in industry. Super-hydrophobic self-cleaning aluminum alloy coating has shown broad application prospects in many fields due to its unique properties. In the field of construction: it can be used for surface treatment of materials such as curtain walls and roofs, reducing cleaning costs and improving the aesthetics of buildings; in the field of transportation: it can be used for the shells of vehicles such as cars and airplanes to reduce rainwater accumulation and stain adhesion, and improve driving safety and aesthetics; in addition, it also has important applications in energy, electronics, military and other fields, such as anti-fouling treatment of solar panels and radar antenna covers. However, in real environments, although super-hydrophobic self-cleaning coatings can effectively repel dust and moisture, they are still unable to remove organic pollutants. These organic pollutants, such as oil stains, resins, etc., often have strong adhesion and can gradually accumulate on the surface of the coating, eventually causing the coating to lose its original super-hydrophobic properties, which not only affects the self-cleaning effect of the coating, but may also damage the long-term use of the coating.

[0004] Therefore, developing a simple and efficient super-hydrophobic self-cleaning aluminum alloy has become one of the problems that technicians in this field need to solve urgently. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention discloses a super hydrophobic self-cleaning aluminum alloy coating and a preparation method thereof. The present invention cooperates between a base coating and a composite coating on an aluminum alloy substrate. The former provides a good adhesion and hydrophobic basis, and the latter provides the main self-cleaning functional characteristics. The combination of the two makes the entire coating system both stable and effectively self-cleaning.

[0006] To achieve the above object, the present invention provides the following technical solutions: The present invention discloses a method for preparing a super-hydrophobic self-cleaning aluminum alloy coating, comprising the following steps: S1. The aluminum alloy substrate is polished, cleaned and dried to obtain a pretreated aluminum alloy substrate; S2. Tetraethoxysilane (TEOS) and anhydrous ethanol are placed in beakers respectively, and the beakers are placed on a magnetic stirrer to stir and mix, and at the same time, an appropriate amount of 0.05M dilute hydrochloric acid is added dropwise into the beaker, and stirring is continued. When the tetraethoxysilane (TEOS) solution in the beaker forms a transparent sol, perfluorooctyl triethoxysilane (PFOTES) is added into the beaker, and stirring is continued to obtain a uniformly dispersed sol; S3. SiO 2 Powder, TiO 2 The powder and PVP were added to another beaker in turn, and an appropriate amount of deionized water was added to the beaker. The beaker was then placed on an ultrasonic disperser for ultrasonic dispersion to obtain SiO 2 / TiO 2 The suspension is then sprayed and granulated to obtain SiO 2 -TiO 2 Composite powder; S4. The SiO prepared in step S3 2 -TiO 2 The composite powder is added into a container containing anhydrous ethanol, and the container is placed on a magnetic stirrer for stirring and mixing. Meanwhile, an appropriate amount of perfluorooctyltriethoxysilane is added into the container, and the stirring and mixing is continued to obtain a composite powder slurry; S5. The sol prepared in step S2 is evenly sprayed on the surface of the aluminum alloy substrate, and dried at 70 to 80° C. to obtain an aluminum alloy base coating; S6. The composite powder slurry prepared in step S4 is evenly sprayed on the aluminum alloy coating base layer obtained in step S5, and dried at 70-80° C. to obtain an aluminum alloy composite coating; S7. Place the aluminum alloy substrate coated with the composite coating obtained in step S6 in an oven and perform heat treatment at 400-450° C. for 1-2 hours to obtain a super-hydrophobic self-cleaning aluminum alloy coating.

[0007] Preferably, in step S2, the volume ratio of tetraethoxysilane (TEOS), anhydrous ethanol and dilute hydrochloric acid is (8-10): (40-45): (8-10).

[0008] Preferably, in step S2, the volume of the perfluorooctyltriethoxysilane (PFOTES) is 5% to 10% of the volume of tetraethoxysilane.

[0009] Preferably, in step S3, the SiO 2 and TiO 2 The mass ratio of SiO 2 The particle size of the powder is 2~5μm. 2 The particle size of the powder is 40~50nm.

[0010] Preferably, in step S3, the mass of the polyvinyl pyrrolidone (PVP) is SiO 2 With TiO 2 2%~4% of the total mass of powder.

[0011] Preferably, in step S3, the parameters of the spray granulation are: inlet air temperature is 150-200°C, outlet air temperature is 70-100°C, and spray pressure is 2-4 bar.

[0012] Preferably, in step S4, the SiO 2 -TiO 2 The mass ratio of the composite powder to anhydrous ethanol is 1:(4~6).

[0013] Preferably, in step S4, the mass of the perfluorooctyltriethoxysilane (PFOTES) is 2% to 4% of the mass of the SiO2-TiO2 composite powder.

[0014] Preferably, in step S5 and step S6, the carrier gas for spraying is air, the pressure range is 1.0-1.2 MPa, the vertical distance between the spray gun and the surface of the aluminum alloy substrate is 16-18 cm, and the speed of the spray gun movement is 0.8-1.0 cm / s.

[0015] The invention also discloses a super-hydrophobic self-cleaning aluminum alloy coating, and the super-hydrophobic self-cleaning aluminum alloy coating can be prepared by adopting the above-mentioned preparation method.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a super-hydrophobic self-cleaning aluminum alloy coating and a composite coating thereof. Through the cooperation between the base coating and the composite coating on the aluminum alloy substrate, the former provides a good adhesion and hydrophobic basis, and the latter provides the main self-cleaning functional characteristics. The combination of the two makes the entire coating system both stable and effectively self-cleaning. The specific mechanism is as follows: (1) The first layer of base coating provides basic hydrophobicity and adhesion: TEOS forms silanol groups (Si-OH) during the hydrolysis process. The presence of silanol groups (Si-OH) allows siloxane molecules to undergo a dehydration condensation reaction with the hydroxyl groups (Al-OH) on the surface of the aluminum alloy to form silicon-oxygen-aluminum bonds (Si-O-Al), allowing the siloxane molecules to firmly adhere to the surface of the aluminum alloy to form a dense film. This chemical bonding not only enhances the bonding strength between the coating and the aluminum alloy substrate, but also improves the durability of the coating. At the same time, When PFOTES is hydrolyzed, it also forms silanol groups (Si-OH), which can undergo condensation reaction with hydroxyl groups (Al-OH) on the surface of aluminum alloys to form silicon-oxygen-aluminum bonds (Si-O-Al). In this way, PFOTES can form a thin film containing fluorinated segments on the surface of aluminum alloys. Because fluorine atoms have strong electronegativity, very low surface tension and extremely high hydrophobicity, the fluorinated segments repel water molecules. The introduction of fluorinated segments significantly reduces the energy of the coating surface, making it difficult for water droplets to adhere, and they are prone to form balls and slide off.

[0017] (2) The second composite coating is composed of SiO containing PFOTES. 2 -TiO 2 The composite powder is not only super-hydrophobic, but also photocatalytically active: SiO 2 -TiO 2 The composite powder combines the high transparency of silicon dioxide with the photocatalytic activity of titanium dioxide. Titanium dioxide can decompose organic pollutants under ultraviolet light and has a self-cleaning effect. 2 It provides a stable skeleton structure. This composite material can decompose surface pollutants through photocatalysis. The introduction of PFOTES can be combined with SiO 2 -TiO 2 The micro-nano structure formed by the composite powder achieves super hydrophobicity. When water droplets touch the surface, they will form a spherical shape due to the super hydrophobicity and micro-nano structure of the surface. 2 The reactive oxygen species generated under light can decompose organic pollutants on the surface. As the water droplets roll, they can carry away the remnants of the decomposed pollutants, thereby keeping the surface clean. This synergistic effect makes the coating not only resistant to water droplet adhesion, but also self-cleaning with the help of the external environment (such as rain and sunlight). DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] The present invention discloses a super-hydrophobic self-cleaning aluminum alloy coating and a preparation method thereof, wherein the preparation method comprises the following steps: S1. The aluminum alloy substrate is polished, cleaned and dried to obtain a pretreated aluminum alloy substrate.

[0020] S2. Place TEOS, anhydrous ethanol and dilute hydrochloric acid in a volume ratio of (8-10): (40-45): (8-10) into a beaker in sequence, and place the beaker on a magnetic stirrer for stirring and mixing. The concentration of the dilute hydrochloric acid is 0.05M. When the TEOS solution in the beaker forms a transparent sol, add PFOTES into the beaker, wherein the volume of PFOTES is 5%-10% of the volume of the above-mentioned TEOS. Continue stirring to obtain a uniformly dispersed sol.

[0021] S3. SiO with a particle size of 2~5μm 2 Powder, TiO with a particle size of 40~50nm 2 Powder and PVP are added into another beaker in sequence (SiO 2 and TiO 2 The mass ratio of PVP is (1~2):1, the mass of SiO 2 With TiO 2 2%~4% of the total mass of the powder), and add an appropriate amount of deionized water into the beaker, and then place the beaker on an ultrasonic disperser for ultrasonic dispersion to obtain SiO 2 / TiO 2 The suspension is then sprayed and granulated under the conditions of an inlet air temperature of 150-200°C, an outlet air temperature of 70-100°C, and a spray pressure of 2-4 bar to obtain SiO 2 -TiO 2 Composite powder.

[0022] S4. The SiO prepared in step S3 2 -TiO 2 The composite powder and anhydrous ethanol are placed in another container at a mass ratio of 1: (4-6), and the container is placed on a magnetic stirrer for stirring and mixing. At the same time, an appropriate amount of PFOTES (wherein the mass of PFOTES is SiO 2 -TiO 2The mixture is stirred and mixed to obtain a composite powder slurry.

[0023] S5. The sol prepared in step S2 is evenly sprayed on the surface of the aluminum alloy substrate under the conditions that the carrier gas is air, the pressure range is 1.0~1.2MPa, the vertical distance between the spray gun and the surface of the aluminum alloy substrate is 16~18cm, and the speed of the spray gun is 0.8~1.0cm / s. After drying at 70~80℃, an aluminum alloy base coating is obtained.

[0024] S6. The composite powder slurry prepared in step S4 is evenly sprayed on the aluminum alloy coating base layer obtained in step S5 under the conditions that the carrier gas is air, the pressure range is 1.0~1.2MPa, the vertical distance between the spray gun and the surface of the aluminum alloy substrate is 16~18cm, and the speed of the spray gun is 0.8~1.0cm / s. After drying at 70~80℃, an aluminum alloy composite coating is obtained.

[0025] S7. Place the aluminum alloy substrate coated with the composite coating obtained in step S6 in an oven and perform heat treatment at 400-450° C. for 1-2 hours to obtain a super-hydrophobic self-cleaning aluminum alloy coating.

[0026] The technical solution of the present invention is further described below in conjunction with specific embodiments: Example 1

[0027] This embodiment provides a method for preparing a super-hydrophobic self-cleaning aluminum alloy coating, and the specific steps are as follows: S1. The aluminum alloy substrate is polished, cleaned and dried to obtain a pretreated aluminum alloy substrate.

[0028] S2. TEOS, anhydrous ethanol, and 0.05M dilute hydrochloric acid are placed in a beaker in a volume ratio of 9:42:9, and the beaker is placed on a magnetic stirrer for stirring and mixing. When the TEOS solution in the beaker forms a transparent sol, PFOTES with a volume of 8% of the above TEOS is added to the beaker, and stirring is continued to obtain a uniformly dispersed sol.

[0029] S3. SiO with a particle size of 3 μm 2 Powder, TiO with a particle size of 45nm 2 The powder is added into another beaker at a mass ratio of 1.5:1, and then the mass of the above SiO 2 With TiO 2 The total weight of the powder was 3% PVP, and an appropriate amount of deionized water was added to the beaker, and then the beaker was placed on an ultrasonic disperser for ultrasonic dispersion to obtain SiO 2 / TiO 2The suspension was then sprayed and granulated under the conditions of an inlet air temperature of 180°C, an outlet air temperature of 80°C, and a spray pressure of 3 bar to obtain SiO 2 -TiO 2 Composite powder.

[0030] S4. The SiO prepared in step S3 2 -TiO 2 The composite powder and anhydrous ethanol are placed in another container at a mass ratio of 1:5, and the container is placed on a magnetic stirrer for stirring and mixing. At the same time, the above-mentioned SiO 2 -TiO 2 Add 3% PFOTES by weight of the composite powder, continue stirring and mixing to obtain a composite powder slurry.

[0031] S5. The sol prepared in step S2 is evenly sprayed on the surface of the aluminum alloy substrate under the conditions that the carrier gas is air, the pressure range is 1.1 MPa, the vertical distance between the spray gun and the surface of the aluminum alloy substrate is 17 cm, and the speed of the spray gun is 0.9 cm / s. After drying at 75°C, an aluminum alloy base coating is obtained.

[0032] S6. The composite powder slurry prepared in step S4 is evenly sprayed on the aluminum alloy coating base layer obtained in step S5 under the conditions that the carrier gas is air, the pressure range is 1.1 MPa, the vertical distance between the spray gun and the surface of the aluminum alloy substrate is 17 cm, and the speed of the spray gun is 0.9 cm / s. After drying at 75°C, an aluminum alloy composite coating is obtained.

[0033] S7. Place the aluminum alloy substrate coated with the composite coating obtained in step S6 in an oven and perform heat treatment at 430° C. for 1.5 h to obtain a super-hydrophobic self-cleaning aluminum alloy coating. Example 2

[0034] This embodiment provides a method for preparing a super-hydrophobic self-cleaning aluminum alloy coating, and the specific steps are as follows: S1. The aluminum alloy substrate is polished, cleaned and dried to obtain a pretreated aluminum alloy substrate.

[0035] S2. Place TEOS, anhydrous ethanol, and 0.05M dilute hydrochloric acid in a volume ratio of 8:40:8 into a beaker, and place the beaker on a magnetic stirrer to stir and mix. When the TEOS solution in the beaker forms a transparent sol, add PFOTES in a volume of 5% of the above TEOS volume into the beaker, and continue stirring to obtain a uniformly dispersed sol.

[0036] S3. SiO with a particle size of 2 μm 2Powder, TiO with a particle size of 40nm 2 The powder is added into another beaker at a mass ratio of 1:1, and then the mass of the above SiO 2 With TiO 2 The total weight of the powder was 2% PVP, and an appropriate amount of deionized water was added to the beaker, and then the beaker was placed on an ultrasonic disperser for ultrasonic dispersion to obtain SiO 2 / TiO 2 The suspension was then sprayed and granulated under the conditions of an inlet air temperature of 150°C, an outlet air temperature of 70°C, and a spray pressure of 2 bar to obtain SiO 2 -TiO 2 Composite powder.

[0037] S4. The SiO prepared in step S3 2 -TiO 2 The composite powder and anhydrous ethanol are placed in another container at a mass ratio of 1:6, and the container is placed on a magnetic stirrer for stirring and mixing. At the same time, the above-mentioned SiO 2 -TiO 2 Add 2% PFOTES by weight of the composite powder, continue stirring and mixing to obtain a composite powder slurry.

[0038] S5. The sol prepared in step S2 is evenly sprayed on the surface of the aluminum alloy substrate under the conditions that the carrier gas is air, the pressure range is 1.0 MPa, the vertical distance between the spray gun and the surface of the aluminum alloy substrate is 16 cm, and the speed of the spray gun is 0.8 cm / s. After drying at 70°C, an aluminum alloy base coating is obtained.

[0039] S6. The composite powder slurry prepared in step S4 is evenly sprayed on the aluminum alloy coating base layer obtained in step S5 under the conditions that the carrier gas is air, the pressure range is 1.0 MPa, the vertical distance between the spray gun and the surface of the aluminum alloy substrate is 16 cm, and the speed of the spray gun is 0.8 cm / s. After drying at 70°C, an aluminum alloy composite coating is obtained.

[0040] S7. Place the aluminum alloy substrate coated with the composite coating obtained in step S6 in an oven and perform heat treatment at 400° C. for 2 h to obtain a super-hydrophobic self-cleaning aluminum alloy coating. Example 3

[0041] This embodiment provides a method for preparing a super-hydrophobic self-cleaning aluminum alloy coating, and the specific steps are as follows: S1. The aluminum alloy substrate is polished, cleaned and dried to obtain a pretreated aluminum alloy substrate.

[0042] S2. Place TEOS, anhydrous ethanol, and 0.05M dilute hydrochloric acid in a volume ratio of 10:45:10 into a beaker, and place the beaker on a magnetic stirrer to stir and mix. When the TEOS solution in the beaker forms a transparent sol, add PFOTES in a volume of 10% of the above TEOS volume into the beaker, continue stirring, and obtain a uniformly dispersed sol.

[0043] S3. SiO with a particle size of 5 μm 2 Powder, TiO with a particle size of 50nm 2 The powder is added into another beaker at a mass ratio of 2:1, and then the mass of the above SiO 2 With TiO 2 The total weight of the powder was 4% PVP, and an appropriate amount of deionized water was added to the beaker, and then the beaker was placed on an ultrasonic disperser for ultrasonic dispersion to obtain SiO 2 / TiO 2 The suspension was then sprayed and granulated under the conditions of an inlet air temperature of 200°C, an outlet air temperature of 100°C, and a spray pressure of 4 bar to obtain SiO 2 -TiO 2 Composite powder.

[0044] S4. The SiO prepared in step S3 2 -TiO 2 The composite powder and anhydrous ethanol are placed in another container at a mass ratio of 1:4, and the container is placed on a magnetic stirrer for stirring and mixing. At the same time, the above-mentioned SiO 2 -TiO 2 4% PFOTES by weight of the composite powder was added, and the mixture was stirred and mixed to obtain a composite powder slurry.

[0045] S5. The sol prepared in step S2 is evenly sprayed on the surface of the aluminum alloy substrate under the conditions that the carrier gas is air, the pressure range is 1.2 MPa, the vertical distance between the spray gun and the surface of the aluminum alloy substrate is 18 cm, and the speed of the spray gun is 1.0 cm / s. After drying at 80°C, an aluminum alloy base coating is obtained.

[0046] S6. The composite powder slurry prepared in step S4 is evenly sprayed on the aluminum alloy coating base layer obtained in step S5 under the conditions that the carrier gas is air, the pressure range is 1.2 MPa, the vertical distance between the spray gun and the surface of the aluminum alloy substrate is 18 cm, and the speed of the spray gun is 1.0 cm / s. After drying at 80°C, an aluminum alloy composite coating is obtained.

[0047] S7. Place the aluminum alloy substrate coated with the composite coating obtained in step S6 in an oven and perform heat treatment at 450° C. for 2 hours to obtain a super-hydrophobic self-cleaning aluminum alloy coating. Example 4

[0048] This embodiment provides a method for preparing a super-hydrophobic self-cleaning aluminum alloy coating, and the specific steps are as follows: S1. The aluminum alloy substrate is polished, cleaned and dried to obtain a pretreated aluminum alloy substrate.

[0049] S2. Place TEOS, anhydrous ethanol, and 0.05M dilute hydrochloric acid in a volume ratio of 10:42:10 into a beaker, and place the beaker on a magnetic stirrer to stir and mix. When the TEOS solution in the beaker forms a transparent sol, add PFOTES in a volume of 7% of the above TEOS volume into the beaker, and continue stirring to obtain a uniformly dispersed sol.

[0050] S3. SiO with a particle size of 3 μm 2 Powder, TiO with a particle size of 50nm 2 The powder is added into another beaker at a mass ratio of 2:1, and then the mass of the above SiO 2 With TiO 2 The total weight of the powder was 4% PVP, and an appropriate amount of deionized water was added to the beaker, and then the beaker was placed on an ultrasonic disperser for ultrasonic dispersion to obtain SiO 2 / TiO 2 The suspension was then sprayed and granulated under the conditions of an inlet air temperature of 150°C, an outlet air temperature of 100°C, and a spray pressure of 4 bar to obtain SiO 2 -TiO 2 Composite powder.

[0051] S4. The SiO prepared in step S3 2 -TiO 2 The composite powder and anhydrous ethanol are placed in another container at a mass ratio of 1:4, and the container is placed on a magnetic stirrer for stirring and mixing. At the same time, the above-mentioned SiO 2 -TiO 2 Add 2% PFOTES by weight of the composite powder, continue stirring and mixing to obtain a composite powder slurry.

[0052] S5. The sol prepared in step S2 is evenly sprayed on the surface of the aluminum alloy substrate under the conditions that the carrier gas is air, the pressure range is 1.0 MPa, the vertical distance between the spray gun and the surface of the aluminum alloy substrate is 18 cm, and the speed of the spray gun is 1.0 cm / s. After drying at 75°C, an aluminum alloy base coating is obtained.

[0053] S6. The composite powder slurry prepared in step S4 is evenly sprayed on the aluminum alloy coating base layer obtained in step S5 under the conditions that the carrier gas is air, the pressure range is 1.2 MPa, the vertical distance between the spray gun and the surface of the aluminum alloy substrate is 17 cm, and the speed of the spray gun is 0.8 cm / s. After drying at 80°C, an aluminum alloy composite coating is obtained.

[0054] S7. Place the aluminum alloy substrate coated with the composite coating obtained in step S6 in an oven and perform heat treatment at 450° C. for 1 hour to obtain a super-hydrophobic self-cleaning aluminum alloy coating. Example 5

[0055] This embodiment provides a method for preparing a super-hydrophobic self-cleaning aluminum alloy coating, and the specific steps are as follows: S1. The aluminum alloy substrate is polished, cleaned and dried to obtain a pretreated aluminum alloy substrate.

[0056] S2. Place TEOS, anhydrous ethanol, and 0.05M dilute hydrochloric acid in a volume ratio of 8:42:8 into a beaker, and place the beaker on a magnetic stirrer to stir and mix. When the TEOS solution in the beaker forms a transparent sol, add PFOTES in a volume of 5% of the above TEOS volume into the beaker, and continue stirring to obtain a uniformly dispersed sol.

[0057] S3. SiO with a particle size of 5 μm 2 Powder, TiO with a particle size of 40nm 2 The powder is added into another beaker at a mass ratio of 1:1, and then the mass of the above SiO 2 With TiO 2 The total weight of the powder was 4% PVP, and an appropriate amount of deionized water was added to the beaker, and then the beaker was placed on an ultrasonic disperser for ultrasonic dispersion to obtain SiO 2 / TiO 2 The suspension was then sprayed and granulated under the conditions of an inlet air temperature of 200°C, an outlet air temperature of 70°C, and a spray pressure of 3 bar to obtain SiO 2 -TiO 2 Composite powder.

[0058] S4. The SiO prepared in step S3 2 -TiO 2 The composite powder and anhydrous ethanol are placed in another container at a mass ratio of 1:5, and the container is placed on a magnetic stirrer for stirring and mixing. At the same time, the above-mentioned SiO 2 -TiO 24% PFOTES by weight of the composite powder was added, and the mixture was stirred and mixed to obtain a composite powder slurry.

[0059] S5. The sol prepared in step S2 is evenly sprayed on the surface of the aluminum alloy substrate under the conditions that the carrier gas is air, the pressure range is 1.2 MPa, the vertical distance between the spray gun and the surface of the aluminum alloy substrate is 16 cm, and the speed of the spray gun is 0.8 cm / s. After drying at 80°C, an aluminum alloy base coating is obtained.

[0060] S6. The composite powder slurry prepared in step S4 is evenly sprayed on the aluminum alloy coating base layer obtained in step S5 under the conditions that the spraying carrier gas is air, the pressure range is 1.0 MPa, the vertical distance between the spray gun and the surface of the aluminum alloy substrate is 18 cm, and the spray gun moves at a speed of 1.0 cm / s. After drying at 75°C, an aluminum alloy composite coating is obtained.

[0061] S7. Place the aluminum alloy substrate coated with the composite coating obtained in step S6 in an oven and perform heat treatment at 400° C. for 2 h to obtain a super-hydrophobic self-cleaning aluminum alloy coating.

[0062] Comparative Example 1 The difference between this comparative example and the above-mentioned Example 1 is that: the surface of the aluminum alloy substrate of this comparative example has only a basic coating, and the specific steps are as follows:

[0063] (1) The aluminum alloy substrate is polished, cleaned, and dried to obtain a pretreated aluminum alloy substrate.

[0064] (2) TEOS, anhydrous ethanol, and 0.05 M dilute hydrochloric acid are placed in a beaker in a volume ratio of 9:42:9, and the beaker is placed on a magnetic stirrer for stirring and mixing. When the TEOS solution in the beaker forms a transparent sol, PFOTES with a volume of 8% of the above TEOS is added to the beaker and stirring is continued to obtain a uniformly dispersed sol.

[0065] (3) The sol prepared in step (2) is evenly sprayed on the surface of the aluminum alloy substrate under the conditions that the carrier gas is air, the pressure range is 1.1 MPa, the vertical distance between the spray gun and the surface of the aluminum alloy substrate is 17 cm, and the speed of the spray gun is 0.9 cm / s. After drying at 75°C, an aluminum alloy base coating is obtained.

[0066] (4) The aluminum alloy substrate coated with the base coating prepared in step (3) is placed in an oven and heat treated at 430° C. for 1.5 h to obtain a super-hydrophobic self-cleaning aluminum alloy coating.

[0067] Comparative Example 2 The difference between this comparative example and the above-mentioned embodiment 1 is that: the surface of the aluminum alloy substrate of this comparative example has only a composite coating, and the specific steps are as follows:

[0068] (1) The aluminum alloy substrate is polished, cleaned, and dried to obtain a pretreated aluminum alloy substrate.

[0069] (2) SiO with a particle size of 3 μm 2 Powder, TiO with a particle size of 45nm 2 The powder is added into another beaker at a mass ratio of 1.5:1, and then the mass of the above SiO 2 With TiO 2 The total weight of the powder was 3% PVP, and an appropriate amount of deionized water was added to the beaker, and then the beaker was placed on an ultrasonic disperser for ultrasonic dispersion to obtain SiO 2 / TiO 2 The suspension was then sprayed and granulated under the conditions of an inlet air temperature of 180°C, an outlet air temperature of 80°C, and a spray pressure of 3 bar to obtain SiO 2 -TiO 2 Composite powder.

[0070] (3) SiO prepared in step (2) 2 -TiO 2 The composite powder and anhydrous ethanol are placed in another container at a mass ratio of 1:5, and the container is placed on a magnetic stirrer for stirring and mixing. At the same time, the above-mentioned SiO 2 -TiO 2 Add 3% PFOTES by weight of the composite powder, continue stirring and mixing to obtain a composite powder slurry.

[0071] (4) The composite powder slurry prepared in step (3) is evenly sprayed on the aluminum alloy coating base layer obtained in step S5 under the conditions that the carrier gas is air, the pressure range is 1.1 MPa, the vertical distance between the spray gun and the surface of the aluminum alloy substrate is 17 cm, and the speed of the spray gun is 0.9 cm / s. After drying at 75°C, an aluminum alloy composite coating is obtained.

[0072] (5) Placing the aluminum alloy substrate coated with the composite coating obtained in step (4) in an oven and heat treating it at 430° C. for 1.5 h to obtain a super-hydrophobic self-cleaning aluminum alloy coating.

[0073] The super-hydrophobic self-cleaning aluminum alloy coatings prepared in the above-mentioned embodiments 1-5 and the super-hydrophobic self-cleaning aluminum alloy coatings prepared in comparative examples 1 and 2 were tested. Ensure that the surface of the test sample in the above-mentioned embodiments is clean, free of oil and other impurities, use a 15μL micro-injector, drop deionized water on the sample surface, and use a water contact angle tester (in accordance with GB / T30693-2014 standard) to measure the static contact angle of the water drop on the surface of the aluminum alloy coating; then install the sample on a bracket that can adjust the tilt angle, use a 15μL micro-injector again, drop deionized water on the sample surface, slowly adjust the tilt angle of the bracket until the water drop begins to slide, and record the minimum tilt angle when the water drop begins to slide, that is, the rolling angle. Subsequently, graphite powder is evenly sprinkled on the surface of the aluminum alloy coating to simulate dust pollution, and deionized water is sprayed on the sample surface using a spray pot or a sprayer to simulate the natural rainfall flushing process, and the cleanliness of the aluminum alloy coating surface after the water droplet is flushed is observed and recorded. The results are shown in Table 1.

[0074] Table 1

[0075] As can be seen from Table 1, the super-hydrophobic self-cleaning aluminum alloy coatings prepared by Examples 1 to 5 exhibit remarkable superior performance. The water contact angles of the coatings of Examples 1 to 5 above all exceed 150°, and the rolling angle is less than 5°, which means that water droplets exhibit extremely high hydrophobicity on these aluminum alloy coatings, that is, water droplets can maintain a nearly spherical shape and easily roll off the surface; in addition, it is observed that there are almost no stains on the surfaces of these embodiments, which shows that they have excellent self-cleaning properties. In contrast, the water contact angles of Comparative Examples 1 and 2 are only 130.5° and 98.7°, respectively, which are far below 150°, and the rolling angles are relatively large, reaching 9° and 11°, which shows that on the surface of the aluminum alloy coating of the comparative example, water droplets tend to spread and are difficult to roll, resulting in the surface being easily contaminated and the self-cleaning effect being poor. In summary, the coatings of Examples 1 to 5 exhibit good hydrophobicity and self-cleaning ability, mainly because when water droplets are dropped on the surface of these coatings, due to the high contact angle and low rolling angle, the water droplets can roll on the surface like small balls and take away surface pollutants such as graphite powder. In contrast, on the coatings of Comparative Examples 1 and 2, water droplets are more likely to spread out and adhere to the surface to form stains, and the self-cleaning ability is relatively weak. This shows that the present invention can effectively improve the self-cleaning performance of the material by rationally designing the base coating and the composite coating on the aluminum alloy substrate; the base coating provides good adhesion and preliminary hydrophobicity, while the composite coating further enhances the hydrophobic properties and self-cleaning function of the surface, and the two complement each other and work together to improve the stability and self-cleaning efficiency of the entire coating system.

[0076] The above is a detailed introduction to a super hydrophobic self-cleaning aluminum alloy coating and a preparation method thereof disclosed in the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention, and the description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for those of ordinary skill in the art, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a super hydrophobic self-cleaning aluminum alloy coating, characterized in that: The following steps are involved: S1. The aluminum alloy substrate is polished, cleaned and dried to obtain a pretreated aluminum alloy substrate; S2. Tetraethoxysilane and anhydrous ethanol were placed in beakers, and the beakers were placed on a magnetic stirrer to stir and mix, and an appropriate amount of 0.05M dilute hydrochloric acid was added dropwise to the beaker, and stirring was continued. When the tetraethoxysilane solution in the beaker formed a transparent sol, perfluorooctyl triethoxysilane was added to the beaker, and stirring was continued to obtain a uniformly dispersed sol; S3. SiO2 powder, TiO2 powder and PVP were added to another beaker in turn, and an appropriate amount of deionized water was added to the beaker, and the beaker was placed on an ultrasonic disperser for ultrasonic dispersion to obtain a SiO2 / TiO2 suspension, and the suspension was sprayed and granulated to obtain a SiO2-TiO2 composite powder; S4. The SiO2-TiO2 composite powder prepared in step S3 is added to a container containing anhydrous ethanol, and placed on a magnetic stirrer for stirring and mixing, and an appropriate amount of perfluorooctyl triethoxysilane is added to the container, and stirring and mixing is continued to obtain a composite powder slurry; S5. The sol prepared in step S2 is evenly sprayed on the surface of the aluminum alloy substrate, and dried at 70 to 80 ° C to obtain an aluminum alloy base coating; S6. The composite powder slurry prepared in step S4 is evenly sprayed on the aluminum alloy coating base layer obtained in step S5, and dried at 70-80° C. to obtain an aluminum alloy composite coating; S7. Place the aluminum alloy substrate coated with the composite coating obtained in step S6 in an oven and perform heat treatment at 400-450° C. for 1-2 hours to obtain a super-hydrophobic self-cleaning aluminum alloy coating.

2. The method for preparing a super hydrophobic self-cleaning aluminum alloy coating according to claim 1, wherein: In step S2, the volume ratio of tetraethoxysilane, anhydrous ethanol and dilute hydrochloric acid is (8-10): (40-45): (8-10).

3. A method for preparing a super hydrophobic self-cleaning aluminum alloy coating according to claim 2, characterized in that, In step S2, the volume of the perfluorooctyltriethoxysilane is 5% to 10% of the volume of the tetraethoxysilane.

4. The method for preparing a super hydrophobic self-cleaning aluminum alloy coating according to claim 1, wherein: In step S3, the mass ratio of SiO2 to TiO2 is (1-2):1; the particle size of the SiO2 powder is 2-5 μm, and the particle size of the TiO2 powder is 40-50 nm.

5. A method for preparing a super hydrophobic self-cleaning aluminum alloy coating according to claim 4, characterized in that, In step S3, the mass of the PVP is 2% to 4% of the total mass of the SiO2 and TiO2 powders.

6. The method for preparing a super-hydrophobic self-cleaning aluminum alloy coating according to claim 1, characterized in that: In step S3, the parameters of the spray granulation are: inlet air temperature is 150-200°C, outlet air temperature is 70-100°C, and spray pressure is 2-4 bar.

7. The method for preparing a super-hydrophobic self-cleaning aluminum alloy coating according to claim 1, characterized in that: In step S4, the mass ratio of the SiO2-TiO2 composite powder to anhydrous ethanol is 1:(4-6).

8. The method for preparing a super-hydrophobic self-cleaning aluminum alloy coating according to claim 7, characterized in that: In step S4, the mass of the perfluorooctyltriethoxysilane is 2% to 4% of the mass of the SiO2-TiO2 composite powder.

9. The method for preparing a super-hydrophobic self-cleaning aluminum alloy coating according to claim 1, characterized in that: In step S5 and step S6, the carrier gas for spraying is air, the pressure range is 1.0-1.2 MPa, the vertical distance between the spray gun and the surface of the aluminum alloy substrate is 16-18 cm, and the speed of the spray gun movement is 0.8-1.0 cm / s.

10. A super-hydrophobic self-cleaning aluminum alloy coating prepared by the preparation method according to any one of claims 1 to 9.

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