Super-hydrophobic composite coating with mechanical firmness, self-cleaning property and high wear resistance as well as method and application of super-hydrophobic composite coating

Abstract

The invention belongs to the field of new materials, and particularly relates to a super-hydrophobic composite coating with mechanical firmness, self-cleaning property and high wear resistance, a method and application thereof. According to the preparation method, epoxy resin (E51) is adopted as a binder, quartz sand, modified F-TiO nano particles and SiO nano particles are combined, and the quartz sand / F-TiO / SiO coated EP super-hydrophobic composite coating of a double-layer structure is prepared through a simple and convenient blade coating-spraying process. According to the coating, through multi-scale hierarchical structure design and low surface energy modification, a static water contact angle of 151 degrees and 1t are achieved; the rolling angle of 5 degrees shows excellent self-cleaning performance on liquid and solid pollutants. A mechanical stability test shows that in a Taber abrasion test, the coating still keeps good hydrophobicity after being abraded for 3000 cycles under the load of 250 g and abraded for 600 cycles under the load of 750 g; after 500 times of adhesive tape stripping experiments, the static water contact angle is still greater than 120 degrees, the rolling angle is as low as 5 degrees, and excellent wear resistance and substrate adhesion are shown.

Description

Technical Field

[0001] This invention belongs to the field of new materials, and specifically relates to a mechanically robust, self-cleaning, highly wear-resistant, superhydrophobic composite coating, its method, and its application. Background Technology

[0002] High contact angle (WCA>150) o and low sliding angle (SA<10) o Superhydrophobic surfaces, due to their anti-fouling, anti-icing, anti-friction, anti-corrosion, wear-resistant, and self-cleaning properties, have attracted much attention in academia and industrial applications. To date, various physicochemical methods have been developed to prepare superhydrophobic surfaces, including chemical etching, spraying, chemical vapor deposition, polymer phase separation, and electrospinning. It is well known that the preparation of superhydrophobic surfaces requires meeting two key conditions simultaneously: (a) a rough surface with micro / nanostructures; and (b) low surface energy materials. However, the microstructure of superhydrophobic surfaces is often fragile and easily damaged by mechanical friction or wear, leading to a decrease in the hydrophobicity of the coating. Although numerous superhydrophobic coatings have been reported, their superhydrophobicity cannot even withstand slight touch and friction. Therefore, preparing stable superhydrophobic surfaces for large-scale industrial applications remains a significant challenge.

[0003] Therefore, achieving good mechanical robustness in superhydrophobic coatings is key to solving this problem. In most cases, techniques for improving the wear resistance of superhydrophobic coatings mainly include constructing protective microstructures to protect fragile nanostructures, using adhesives to bond the coating material to a specific substrate, and methods to enable the surface to self-heal. The simplest and most feasible method to obtain a robust superhydrophobic coating is to embed micro / nano-inorganic additives with the desired mechanical stability, such as SiO2 particles, into a polymer binder. For example, some studies have used epoxy resin as a binder, along with hexadecyltrimethoxysilane-modified SiO2 and KH570-modified cellulose nanofibers, to create a wear-resistant superhydrophobic composite coating. By adjusting the ratio of epoxy resin to SiO2, a static water contact angle of 153.5° was achieved. o Based on this, KH570 modified cellulose nanofibers were added as a nano-reinforcing phase, significantly improving the coating's wear resistance and adhesion, preventing the collapse of the micro / nano structure, and maintaining good hydrophobicity even after 100 cycles of sandpaper abrasion and tape peeling. Another study proposed a wear-resistant honeycomb armor design using femtosecond laser micromachining and magnetron sputtering of NiCrAlY / YSZ coatings. This layered protection system employs a micron-scale honeycomb structure, physically encapsulating the fragile nanostructure and multilayer ceramic reinforcement materials. Extremely high wettability (CA: 162 ± 1.7) was achieved. o SA: 3.8 ± 0.3 oIt exhibits unprecedented durability under conditions including UV radiation (168 hours), chemical exposure (pH 1-14, 168 hours), sand / water impact, and simulated weathering. Even after 300 cm of abrasion on sandpaper, the CA (Chemical Acid) remains at 152°. However, this method requires a complex manufacturing process. To date, designing and scaling up the production of a universal, ultra-durable self-cleaning coating remains a challenge.

[0004] Spraying methods offer advantages such as ease of operation, controllable cost, and suitability for large-area application, which is beneficial for the research and application of superhydrophobic materials. Therefore, this invention utilizes epoxy resin (E51), modified nano-TiO2, nano-silica, and quartz sand to design and prepare a double-layer superhydrophobic quartz sand / F-TiO2 / SiO2@EP coating with excellent mechanical stability through simple scraping and spraying techniques. The microstructure, chemical composition, surface wettability changes, and mechanical stability of the coating were systematically studied. The coating exhibits 151... o Static water contact angle, <5 o The coating exhibits a high water roll-off angle, achieving a superhydrophobic effect and demonstrating excellent cleaning ability against liquid and solid contaminants on its surface. Simultaneously, the coating exhibits excellent abrasion resistance; in Taber abrasion tests, it maintained its superior hydrophobic properties after 600 cycles under a 750g load and 3000 cycles under a 250g load. Therefore, the proposed coating shows promise for practical applications, particularly providing a foundation for outdoor applications. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this invention provides a mechanically robust, self-cleaning, highly wear-resistant, superhydrophobic composite coating, method, and application thereof.

[0006] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a mechanically robust, self-cleaning, and highly wear-resistant superhydrophobic composite coating. The composite coating is a double-layer structured quartz sand / F-TiO2 / SiO2@EP superhydrophobic composite coating. The static water contact angle of the composite coating reaches 151° and the roll-off angle is <5°. In the Taber abrasion test, it remains hydrophobic after 3000 cycles under a 250 g load and 600 cycles under a 750 g load, and the contact angle is still >130° after 500 tape peels.

[0007] In a first aspect, the present invention provides a method for preparing a mechanically robust, self-cleaning, and highly wear-resistant superhydrophobic composite coating, comprising the following steps: Step 1: Preparation of hydrophobic F-TiO2 nanoparticles TiO2 nanoparticles were added to a beaker containing anhydrous ethanol, and a uniform suspension was obtained after ultrasonic treatment and magnetic stirring. PFTMS was then quickly added to the TiO2 / ethanol suspension, stirred, and dried in an oven to obtain PFTMS-modified TiO2 nanoparticles, i.e., F-TiO2 nanoparticles. Step 2: Preparation of superhydrophobic quartz sand / F-TiO2 / SiO2@EP coating Wash the glass plate alternately with ethanol and distilled water, then dry it for later use; weigh epoxy resin E51 and curing agent N-aminoethyl-γ-aminopropyltrimethoxysilane (KH-792), dissolve them in anhydrous ethanol, 60 o Stir for 10 minutes; add quartz sand and stir evenly, then spread evenly onto a glass plate and place in an oven at 60°C. o C is used for curing; next, F-TiO2 nanoparticles are dispersed in anhydrous ethanol, followed by the addition of E51 epoxy resin and curing agent KH-792. The mixture is magnetically stirred to form a uniform suspension; the suspension is then rapidly sprayed onto the surface of E51@quartz sand and placed in a 60°C oven for curing to obtain a quartz sand / F-TiO2 / SiO2@EP coating.

[0008] Furthermore, in step one, the mass ratio of TiO2 nanoparticles to anhydrous ethanol is 14:100.

[0009] Furthermore, in step one, the mass ratio of ethanol to PFTMS is 100:1.

[0010] Furthermore, in step one, the oven temperature is 60℃.

[0011] Furthermore, in step two, the mass ratio of epoxy resin E51 to curing agent N-aminoethyl-γ-aminopropyltrimethoxysilane is 1:0.8.

[0012] Furthermore, in step two, the mass ratio of quartz sand to E51 is 3:5.

[0013] Furthermore, in step two, 1 g of F-TiO2, 15 g of anhydrous ethanol, 1 g of E51, and 0.8 g of curing agent are used. Furthermore, in step two, during the spraying process, the spray gun is kept 15-20 cm away from the substrate, and the spraying pressure is 0.3 MPa.

[0014] Thirdly, this invention provides the application of mechanically robust, self-cleaning, and highly wear-resistant superhydrophobic composite coatings in the fields of building exterior walls and outdoor equipment.

[0015] Compared with the prior art, the advantages of the present invention are as follows: This invention utilizes epoxy resin (E51) as a binder, combined with quartz sand, modified F-TiO2 nanoparticles, and SiO2 nanoparticles, to prepare a two-layer quartz sand / F-TiO2 / SiO2@EP superhydrophobic composite coating through a simple scraping-spraying process. This coating, through multi-scale hierarchical structural design and low surface energy modification, achieves a static water contact angle of 151° and a roll-off angle of <5°, exhibiting excellent self-cleaning properties against liquid and solid contaminants. Mechanical stability tests show that in Taber abrasion tests, the coating maintains good hydrophobicity after 3000 cycles of wear under a 250 g load and 600 cycles of wear under a 750 g load; after 500 tape peel tests, the static water contact angle remains greater than 120°, and the roll-off angle is as low as 5°, demonstrating excellent wear resistance and substrate adhesion. The coating preparation process proposed in this study is simple to operate, cost-controllable, and easy to apply over large areas, providing a feasible solution for the practical application of superhydrophobic coatings in complex environments such as outdoors. Attached Figure Description

[0016] The invention will now be further described with reference to the accompanying drawings.

[0017] Figure 1 shows a schematic diagram of the preparation of superhydrophobic quartz sand / F-TiO2 / SiO2@EP coating; (a) the preparation process of superhydrophobic F-TiO2 nanoparticles, (b) a schematic diagram of the preparation process of superhydrophobic quartz sand / F-TiO2 / SiO2@EP coating. Figure 2. Optical images of (a) pristine TiO2 and (b) colored water droplets on F-TiO2 nanoparticles; (c) FTIR comparison of pristine TiO2 and F-TiO2 nanoparticles. Figure 3 shows the effect of different component contents on the static water contact angle and roll-off angle of the coating; (a) mass ratio of E51 to quartz sand; (b) mass ratio of F-TiO2 to SiO2; (c) total mass ratio of E51 to F-TiO2 and SiO2; (d) photographs of coloring droplets on the quartz sand / F-TiO2 / SiO2@EP coating and water splashing; (e) photograph of the self-cleaning performance of the quartz sand / F-TiO2 / SiO2@EP coating; (f) photograph of the silver mirror phenomenon of the quartz sand / F-TiO2 / SiO2@EP coating in water. Figure 4 shows (a, b, c) SEM images of the quartz sand / F-TiO2 / SiO2@EP coating at different magnifications; (d, e, f, g, h, i) EDS spectra and elemental distribution diagrams of the prepared superhydrophobic quartz sand / F-TiO2 / SiO2@EP coating. Figure 5 shows (a) a photograph of the Taber abrasion tester, weights, and abrasion coating; and (b) a photograph of colored water droplets sliding off the coating after the Taber abrasion test. Figure 6. Changes in the mass of the Taber before and after wear: (a) 750 g, (b) 250 g; Changes in the rolling angle of the Taber before and after wear: (a) 750 g, (b) 250 g; Figure 7 shows (a) the tape peeling test and the static water contact angle and sliding photograph of the coating after 500 tape peeling tests; (b) the relationship between the number of coating peeling tests and the static water contact angle; and (c) the relationship between the number of coating peeling tests and the water roll-off angle. Detailed Implementation

[0018] The invention will now be further described with reference to the accompanying drawings.

[0019] Materials, reagents and instruments Nano-titanium dioxide (TiO2, 100 nm, 99.8%) nanoparticles, silica sand (40-60 mesh), nano-silica (SiO2, 500 nm, 99.5%), 1H,1H,2H,2H-perfluorodecyltrimethoxysilane (PFTMS, 97%), epoxy resin (E51), N-aminoethyl-γ-aminopropyltrimethoxysilane (KH-792) were purchased from Shanghai Maclean Biochemical Co., Ltd., and anhydrous ethanol (C2H6O, 99.7%) was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0020] Example 1 A mechanically robust, self-cleaning, and highly wear-resistant superhydrophobic composite coating is disclosed. The composite coating is a two-layer structure quartz sand / F-TiO2 / SiO2@EP superhydrophobic composite coating. The static water contact angle of the composite coating reaches 151° and the roll-off angle is <5°. In the Taber abrasion test, it remains hydrophobic after 3000 cycles under a 250 g load and 600 cycles under a 750 g load. After 500 tape peels, the contact angle is still >130°.

[0021] The preparation method includes the following steps: Step 1: Preparation of hydrophobic F-TiO2 nanoparticles TiO2 nanoparticles were added to a beaker containing anhydrous ethanol, and a homogeneous suspension was obtained after ultrasonic treatment and magnetic stirring. PFTMS was then rapidly added to the TiO2 / ethanol suspension, stirred, and dried in an oven to obtain PFTMS-modified TiO2 nanoparticles, i.e., F-TiO2 nanoparticles. The mass ratio of TiO2 nanoparticles to anhydrous ethanol was 14:100, the mass ratio of ethanol to PFTMS was 100:1, and the oven temperature was 60℃. Step 2: Preparation of superhydrophobic quartz sand / F-TiO2 / SiO2@EP coating Wash the glass plate alternately with ethanol and distilled water, then dry it for later use; weigh epoxy resin E51 and curing agent N-aminoethyl-γ-aminopropyltrimethoxysilane, dissolve them in anhydrous ethanol, 60 o Stir for 10 minutes; add quartz sand and stir evenly, then spread evenly onto a glass plate and place in an oven at 60°C. o C is used for curing; next, F-TiO2 nanoparticles are dispersed in anhydrous ethanol, followed by the addition of E51 epoxy resin and curing agent KH-792. The mixture is magnetically stirred to form a uniform suspension; this suspension is then rapidly sprayed onto the surface of E51@quartz sand and placed in a 60℃ oven for curing to obtain a quartz sand / F-TiO2 / SiO2@EP coating. The mass ratio of epoxy resin E51 to curing agent N-aminoethyl-γ-aminopropyltrimethoxysilane is 1:0.8, and the mass ratio of quartz sand to E51 is 3:5. Specifically, 1 g of F-TiO2, 15 g of anhydrous ethanol, 1 g of E51, and 0.8 g of curing agent are used. During spraying, the spray gun is kept 15-20 cm away from the substrate, and the spraying pressure is 0.3 MPa.

[0022] Specifically: Preparation of hydrophobic F-TiO2 nanoparticles 12 g of TiO2 nanoparticles were added to a beaker containing 200 mL of anhydrous ethanol. A homogeneous suspension was obtained after sonication and magnetic stirring. Then, 4 mL of PFTMS was rapidly added to the TiO2 / ethanol suspension. The mixture was magnetically stirred at room temperature for 4 h, and then placed in a 60°C container. o TiO2 nanoparticles modified with PFTMS, referred to as F-TiO2 nanoparticles, were obtained by drying in an oven at C. The specific process is shown in Figure 1a.

[0023] Preparation of superhydrophobic quartz sand / F-TiO2 / SiO2@EP coating Wash the glass plate alternately with ethanol and distilled water, then dry it for later use. Weigh 1 g of epoxy resin E51 and 1 g of curing agent N-aminoethyl-γ-aminopropyltrimethoxysilane (KH-792), dissolve them in 10 mL of anhydrous ethanol, and set aside at 60°C. o Stir for 10 minutes. Add 1 g of quartz sand and stir well. Then, evenly coat the mixture onto a glass plate and place it in an oven at 60°C. oCuring was then performed at C. Next, 1.0 g of F-TiO2 nanoparticles were dispersed in 25 mL of anhydrous ethanol, followed by the addition of 0.65 g of E51 epoxy resin and 0.65 g of curing agent KH-792. The mixture was magnetically stirred to form a uniform suspension. This suspension was then rapidly sprayed onto the surface of E51@quartz sand and placed in an oven at 60°C. o C is used for curing to obtain a quartz sand / F-TiO2 / SiO2@EP coating. The specific process is shown in Figure 1b.

[0024] Example 2 Characterization and Testing (1) Structural characterization The surface morphology and thickness of the coating were observed using a scanning electron microscope (SEM, Hitachi Regulus 8220). The elemental composition was analyzed using energy-dispersive spectroscopy (EDS, EDAXOctane).

[0025] (2) Characterization of wettability The contact angle of the coating was measured using a DSA25S (KRü SS, Germany). During the measurement, approximately 4 microliters of water were dropped onto the coating surface by squeezing the syringe. After the droplet stabilized, a side view was taken to measure the contact angle.

[0026] (3) Taber wear test The abrasion resistance of materials was evaluated using a Taber abrasion tester according to ASTM D4060 standard. The experiment used a Calibrase® Cs-10 grinding wheel manufactured by Taber® Industries, applying two loads of 250 grams and 750 grams respectively. The test object was a 10 cm diameter coated glass substrate.

[0027] (4) Fourier Transform Infrared Spectroscopy (FTIR) The chemical composition of TiO2 and F-TiO2 nanoparticles was analyzed using Fourier transform infrared spectroscopy (FTIR, Thermo Fisher Scientific Nicolet iS10).

[0028] Example 3 Results and Discussion Wetting properties, self-cleaning properties and chemical composition Figure 2 Images a and b show optical photographs of water droplets stained on the surfaces of pristine TiO2 particles and modified F-TiO2 particles. The stained water droplets exhibit wetting behavior on the pristine TiO2 surface, indicating that the nanoparticles are hydrophilic. In contrast, the stained water droplets form spherical shapes on the F-TiO2 particle surface, displaying a typical Cassie-Baxter interface non-wetting contact state. This confirms that TiO2 nanoparticles acquire superhydrophobicity after PFTMS molecular modification. Figure 2c shows the FTIR spectra of TiO2 particles before and after PFTMS modification. Compared with the original TiO2 particles, the modified F-TiO2 particles exhibit several new absorption peaks. 1068 cm⁻¹ −1 The peaks at 1204 and 1146 cm⁻¹ are attributed to the asymmetric stretching vibrations of the Si-O-Ti bonds. Additionally, the peaks at 1204 and 1146 cm⁻¹ are also significant. −1 The absorption bands observed can be attributed to the stretching vibrations of the -CF3 and -CF2 groups in the PFTMS molecule. FTIR results confirm the successful PFTMS grafting, which effectively reduces the surface energy of TiO2 particles and achieves superhydrophobicity.

[0029] The overall balance between wettability and mechanical properties is key to the practical application of coatings, while the nano / micro-level layered structure of the surface is an important factor in regulating its surface wettability, especially its superhydrophobicity. Figure 3 This demonstrates how to achieve a perfect combination of superhydrophobicity and wear resistance by controlling the content of various components in a bilayer. As is well known, surface wettability requires not only reducing the surface energy of the solid-liquid interface but also controlling the micro / nano hierarchical structure. In the preparation of the bottom layer, a suitable ratio of quartz sand to E51 epoxy resin needs to be constructed to control the interparticle spacing of the bottom layer, allowing the top layer of nano-sized F-TiO2 to adhere to it, thereby achieving superhydrophobicity. Figure 3 As shown in Figure a, with the increase of quartz sand content, the static water contact angle of the coating decreases while the roll-off angle increases. Two different particle sizes were used in the top layer: modified F-TiO2 (100 nm) and SiO2 (500 nm). These two different particle sizes constructed a nano-hierarchical rough structure. It was found that when the mass ratio of F-TiO2 to SiO2 was 10:3, the coating exhibited the best superhydrophobic effect, reaching 151 nm. o Meanwhile, the sliding angle is as low as 2 o The overall mechanical properties of the coating benefit from the layered curing of the two epoxy resin layers, with the content of the top epoxy resin affecting the balance between overall mechanical properties and superhydrophobic properties. For example... Figure 3 As shown in c, when the ratio of E51 to the total particle mass is 1:2, a high contact angle (151°) can be ensured for the coating while maintaining mechanical properties. o ) and low roll angle (2 o By modulating the interaction between the bilayer particles and the binder, we prepared a coating with excellent superhydrophobic properties. Figure 3 d. Optical photographs of the dyeing liquid on quartz sand / F-TiO2 / SiO2@EP and water spray on the coating surface. Regarding the self-cleaning properties of the quartz sand / F-TiO2 / SiO2@EP coating, solid contaminants were sprayed onto the coating surface, and it was found that the solid contaminants on the surface could be easily removed by water droplets. Figure 3e). Simultaneously, immersing the coating in water reveals the classic silver mirror phenomenon ( Figure 3 f), confirming that the quartz sand / F-TiO2 / SiO2@EP coating has excellent superhydrophobicity.

[0030] Figure 4 Image a shows SEM images of the prepared superhydrophobic silica sand / F-TiO2 / SiO2@EP coating at different magnifications. At low magnification, numerous protrusions are visible on the surface of the silica sand / F-TiO2 / SiO2@EP coating, mainly composed of large-sized silica sand particles embedded in the underlying epoxy resin. These large-sized silica sand structures provide ample space for the top layer of silica sand / F-TiO2 / SiO2@EP, allowing it to fill the gaps between the large-sized silica sand particles and cover their surface. At high magnification, FE-SEM images show that the large-sized silica surface and gaps are densely covered by the superhydrophobic F-TiO2@EP layer. The F-TiO2 nanoparticles are interconnected with the micro-nano binary structure of EP. Figure 4 (b, c). The formation of these multi-scale hierarchical structures, coupled with the presence of low surface energy F-TiO2 particles, helps to trap air cushions in the structural gaps, thus forming a stable and continuous air layer. The significant reduction in solid-liquid contact area and surface energy is the key reason for achieving the designed superhydrophobicity of the bilayer quartz sand / F-TiO2 / SiO2@EP coating. To further investigate the elemental composition and distribution of the coating surface, Figure 4 The diagram shows the EDS spectrum and elemental distribution. The EDS spectrum confirmed the presence of Si, C, O, F, and Ti, with atomic percentages of 12.79%, 47.37%, 36.49%, 2.54%, and 0.8%, respectively. The F signal further confirmed the successful grafting of low surface energy PFTMS molecules onto the TiO2 particles. Furthermore, the elemental distribution shows a highly uniform distribution of all elements on the coating surface, which is crucial for achieving a stable and durable superhydrophobic coating.

[0031] Mechanical stability test of quartz sand / F-TiO2 / SiO2@EP coating As a protective barrier between the substrate and the external environment, the mechanical strength of the coating is a key factor in evaluating its outdoor performance. A limitation of traditional coatings is their susceptibility to mechanical damage due to their micron / nanoscale roughness, making it difficult to balance wettability and abrasion resistance. The abrasion resistance of our samples was measured using a Taber abrasion tester. Figure 5As shown in Figure a, we used a 750 g load and a matching abrasive wheel to conduct abrasion tests on the quartz sand / F-TiO2 / SiO2@EP coating. The coating material was sprayed onto a ring-shaped glass substrate of specified dimensions, and then the abrasion test was performed at a fixed position. After 600 cycles of abrasion under a 750 g load, the dyed water droplets could still quickly slide off the surface of the quartz sand / F-TiO2 / SiO2@EP coating without leaving any marks, maintaining excellent hydrophobic and self-cleaning properties. Figure 5 b).

[0032] During wear under a 750 g load, we test the coating condition every 200 cycles. Figure 6 As can be seen, the coating quality after 600 cycles differed from that before the wear test by only 0.0215g, which fully demonstrates the coating's hardness and mechanical strength. Furthermore, we tested the roll-off angle of the coating before and after wear. After 600 cycles of wear under a 750g load, the roll-off angle remained at 7°. o The following properties can still be maintained, including surface hydrophobicity and self-cleaning. Figure 6 c). In addition, we conducted more destructive tests on the quartz sand / F-TiO2 / SiO2@EP coating under a 250 g load. After 3000 wear cycles, the coating mass decreased by only 0.0338 g, and the water roll-off angle remained at 8°. o the following( Figure 6 (b, d) Wear tests demonstrated the sustained hydrophobicity of the quartz sand / F-TiO2 / SiO2@EP coating, and the bilayer quartz sand / F-TiO2 / SiO2@EP coating constructed in this study exhibited excellent interfacial mechanical stability. The enhanced interfacial stability is mainly attributed to the multi-scale bilayer structure design. First, the top layer of quartz sand / F-TiO2 / SiO2@EP contains epoxy resin, ensuring structural uniformity and wear resistance. Even after wear, the F-TiO2@EP layer retains its superhydrophobicity. Furthermore, the large-scale quartz sand structure in the bottom layer acts as a skeletal support for the coating, making a significant contribution to the overall hardness.

[0033] Thanks to its dual-layer resin design, the quartz sand / F-TiO2 / SiO2@EP coating exhibits excellent adhesion. The coating was sprayed onto a smooth glass surface, and its adhesion performance was tested using a tape peel test. The sample was fixed on a worktable, and tape was applied to the coating surface. A 2 kg weight was slowly rolled over the tape-covered surface, ensuring close contact between the tape and the coating. The tape was then quickly peeled off, completing one peel cycle, as shown in Figure 7a. The static water contact angle was measured every 100 peel cycles, as shown in Figure 7b. The results showed that the static water contact angle decreased slightly with increasing peel cycles. After 500 peel cycles, a small amount of peeling occurred on the coating surface, but the static water contact angle remained greater than 120°. o Even after 500 peel tests, the water roll-off angle on the coating surface remained as low as 5. o This indicates that the coating has good adhesion to the substrate.

Claims

1. A mechanically robust, self-cleaning, highly wear-resistant, superhydrophobic composite coating, characterized in that, The composite coating is a double-layer quartz sand / F-TiO2 / SiO2@EP superhydrophobic composite coating. The static water contact angle of the composite coating reaches 151° and the roll-off angle is <5°. In the Taber wear test, it still maintains a hydrophobic state after 3000 cycles under a 250 g load and 600 cycles under a 750 g load, and the contact angle is still >130° after 500 tape peels.

2. The method for preparing the mechanically robust, self-cleaning, and highly wear-resistant superhydrophobic composite coating according to claim 1, comprising the following steps: Step 1: Preparation of hydrophobic F-TiO2 nanoparticles TiO2 nanoparticles were added to a beaker containing anhydrous ethanol, and a uniform suspension was obtained after ultrasonic treatment and magnetic stirring. PFTMS was then quickly added to the TiO2 / ethanol suspension, stirred, and dried in an oven to obtain PFTMS-modified TiO2 nanoparticles, i.e., F-TiO2 nanoparticles. Step 2: Preparation of superhydrophobic quartz sand / F-TiO2 / SiO2@EP coating Wash the glass plate alternately with ethanol and distilled water, then dry it for later use; weigh epoxy resin E51 and curing agent N-aminoethyl-γ-aminopropyltrimethoxysilane, dissolve them in anhydrous ethanol, 60 o Stir for 10 minutes; add quartz sand and stir evenly, then spread evenly onto a glass plate and place in an oven at 60°C. o C is used for curing; next, F-TiO2 nanoparticles are dispersed in anhydrous ethanol, followed by the addition of E51 epoxy resin and curing agent KH-792. The mixture is then magnetically stirred to form a uniform suspension. The suspension was then rapidly sprayed onto the E51@quartz sand surface and cured in a 60°C oven to obtain a quartz sand / F-TiO2 / SiO2@EP coating.

3. The method according to claim 2, characterized in that, In step one, the mass ratio of TiO2 nanoparticles to anhydrous ethanol is 14:

100.

4. The method according to claim 2, characterized in that, In step one, the mass ratio of ethanol to PFTMS is 100:

1.

5. The method according to claim 2, characterized in that, In step one, the oven temperature is 60℃.

6. The method according to claim 2, characterized in that, In step two, the mass ratio of epoxy resin E51 to curing agent N-aminoethyl-γ-aminopropyltrimethoxysilane is 1:0.

8.

7. The method according to claim 2, characterized in that, In step two, the mass ratio of quartz sand to E51 is 3:

5. According to the method described in claim 2, in step two, 1 g of F-TiO2, 15 g of anhydrous ethanol, 1 g of E51, and 0.8 g of curing agent are used.

8. The method according to claim 2, characterized in that, In step two, during the spraying process, the spray gun is kept 15-20 cm away from the substrate, and the spraying pressure is 0.3 MPa.

9. The application of the composite coating of claim 1 in the fields of building exterior walls and outdoor equipment.

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