A multifunctional smart coating of F-MXene / SiO2 / PVDF / FP, its preparation method and application

Abstract

This invention discloses a multifunctional smart coating of F-MXene / SiO2 / PVDF / FP, its preparation method, and its application, belonging to the field of surface protection technology for metallic materials. The method involves composite MXene with SiO2, followed by PFDTES fluorination modification and the addition of PVDF and Al. 3+ A fluorescent probe was prepared using a dip-coating method to create a coating. This coating exhibits Ti3C2T... x The composite micro / nano hierarchical rough structure of MXene two-dimensional sheets and fluorinated SiO2 nanoparticles, with PVDF forming a bonding network and fluorescent probes uniformly dispersed within, provides the coating of this invention. This coating combines multiple functions, including superhydrophobicity, long-term corrosion protection, mechanical stability, and in-situ visual corrosion monitoring. The process of this invention is simple and low-cost, making it suitable for intelligent corrosion protection of metal components in marine engineering, aerospace, and other fields.

Description

Technical Field

[0001] This invention belongs to the field of metal material surface protection technology, specifically relating to a multifunctional intelligent coating of F-MXene / SiO2 / PVDF / FP that integrates superhydrophobicity, long-term corrosion protection, mechanical stability and in-situ visual monitoring of corrosion, as well as its preparation method and application. Background Technology

[0002] Metal corrosion is a critical issue affecting the service safety and lifespan of marine engineering, aerospace, and new energy equipment. Statistics show that global economic losses due to metal corrosion account for 3% to 5% of GDP annually. Inspired by the unique wettability of natural biological surfaces such as lotus leaves and water hyacinths, superhydrophobic coatings, through the construction of micro-nano rough structures and low surface energy modification, can form an air cushion layer to block corrosive media, thereby significantly slowing down the metal corrosion process and providing a new approach to metal protection.

[0003] In recent years, two-dimensional transition metal carbides / nitrides (MXenes), as emerging nanomaterials, have shown great potential in the field of anti-corrosion coatings due to their excellent mechanical properties, ion barrier properties, and surface modifiability. Ti3C2T x MXene is obtained by selectively etching a Ti3AlC2 precursor. Its layered structure can create a "maze effect" in the coating, extending the penetration path of corrosive media. At the same time, the abundant functional groups (-OH, -O, -F) on the surface provide active sites for chemical modification. Studies have shown that fluorinated MXene can construct micro-nano rough structures and, combined with low surface energy materials, achieve superhydrophobic properties and water contact angles of over 158°.

[0004] However, existing MXene-based anti-corrosion coatings primarily focus on improving static barrier performance. The protective performance of these coating systems declines sharply after mechanical damage, making it difficult to achieve long-term protection for metallic materials. Furthermore, they cannot simultaneously monitor the corrosion process in real-time and in-situ, thus lacking early warning capabilities. Aluminum alloys release Al during corrosion. 3+ Its concentration change can directly reflect the degree of corrosion, but traditional corrosion detection methods are difficult to achieve real-time, in-situ monitoring. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an F-MXene / SiO2 / PVDF / FP multifunctional smart coating, its preparation method, and its applications. This coating mimics the rough micro-nano hierarchical structure of the surface of *Lysimachia christinae*, possessing not only excellent superhydrophobicity, self-cleaning properties, mechanical stability, and long-term corrosion resistance, but also introducing Al... 3+ Specific fluorescent probes enable in-situ, visualized, and real-time monitoring of the corrosion process of aluminum alloys.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing an F-MXene / SiO2 / PVDF / FP multifunctional smart coating, comprising the following steps: (1) Preparation of F-MXene / SiO2 / PVDF materials: Anhydrous ethanol and 25% ammonia solution were mixed evenly, MXene and SiO2 nanoparticles were added, followed by TEOS, and the mixture was stirred at room temperature. Then PFDTES and PVDF were added sequentially, and the mixture was first ultrasonically stirred and then magnetically stirred to obtain a uniform and stable F-MXene / SiO2 / PVDF suspension. (2) Preparation of F-MXene / SiO2 / PVDF / FP multifunctional smart coating: The obtained F-MXene / SiO2 / PVDF suspension was reacted with Al 3+ Fluorescent probes are mixed evenly to obtain a mixed solution of F-MXene / SiO2 / PVDF / FP. After pretreatment of the aluminum alloy substrate, it is coated with DMF solution of PVDF and the mixed solution of F-MXene / SiO2 / PVDF / FP in sequence, and then dried and cured to obtain the multifunctional smart coating of F-MXene / SiO2 / PVDF / FP.

[0007] Furthermore, in step (1), the MXene is Ti3C2T. x MXene.

[0008] As a preferred option, Ti3C2T x The preparation method of MXene is as follows: LiF powder is slowly added to HCl solution and stirred until completely dissolved to form a homogeneous and transparent etching solution; the container containing the etching solution is placed in an ice-water bath, and Ti3AlC2 powder is slowly added. After the powder is completely dispersed, it is transferred to an oil bath and the reaction is continuously magnetically stirred; after the reaction is completed, the mixture is centrifuged and washed several times until the pH of the supernatant is >6, and the lower black precipitate is collected; the precipitate is freeze-dried to obtain Ti3C2T x MXene powder.

[0009] Preferably, the ratio of the LiF, Ti3AlC2 and HCl solutions is 0.6 g: 0.5 g: 10 mL.

[0010] Preferably, the concentration of the HCl solution is 9 mol / L, the temperature of the ice-water bath is controlled at 0-5℃, the temperature of the oil bath is controlled at 40℃, the stirring time is 48h, and the freeze-drying temperature is -50℃ for 12h.

[0011] Furthermore, in step (1), the ratio of the amounts of MXene, SiO2, anhydrous ethanol, ammonia, TEOS, PVDF and PFDTES is 0.15g:0.15g:11mL:1.5mL:0.25mL:1g:0.2mL.

[0012] Further, in step (2), the F-MXene / SiO2 / PVDF suspension and Al 3+ The mass ratio of the fluorescent probe is 100:1.

[0013] Further, in step (2), the Al 3+ The fluorescent probe is 8-hydroxyquinoline, with an excitation wavelength of 365 nm and an emission wavelength of 450 nm.

[0014] Further, in step (2), the pretreatment method of the aluminum alloy substrate is as follows: the aluminum alloy substrate is polished with 800-grit, 1000-grit, and 2000-grit sandpaper in sequence until the surface is flat to remove the oxide layer, and then ultrasonically cleaned in anhydrous ethanol and acetone for 10 minutes each, and dried at 60°C for 30 minutes for later use.

[0015] Further, in step (2), the method for preparing the PVDF DMF solution is as follows: dissolve PVDF in DMF, heat in an oil bath at 60°C and stir for 30 min to obtain the solution; wherein, the ratio of PVDF to DMF is 1g:20mL.

[0016] Further, in step (2), the aluminum alloy substrate is 6061 aluminum alloy.

[0017] Secondly, the present invention provides an F-MXene / SiO2 / PVDF / FP multifunctional smart coating prepared by the above-mentioned preparation method, wherein the coating has Ti3C2T x A composite micro / nano hierarchical rough structure of MXene two-dimensional sheets and SiO2 nanoparticles modified with PFDTES, with PVDF forming a flexible bonding network, and Al 3+ The fluorescent probe is uniformly dispersed within it.

[0018] Thirdly, the present invention also provides the application of the above-mentioned F-MXene / SiO2 / PVDF / FP multifunctional smart coating in aluminum alloy corrosion protection.

[0019] Compared with the prior art, the beneficial technical effects of the present invention are: (1) This invention utilizes Ti3C2T xThe labyrinth effect of MXene two-dimensional sheets, combined with SiO2 nanoparticles and PFDTES fluorination modification, constructs a biomimetic fractal micro-nano rough structure. Furthermore, PFDTES forms covalent bonds with MXene surface functional groups and SiO2, enabling the prepared F-MXene / SiO2 / PVDF / FP coating to achieve a water contact angle of up to 153.7° and a roll-off angle as low as 0.9°. It maintains superhydrophobic stability in acidic and alkaline environments, and its air trapping effect and corrosive media barrier ability are significantly better than traditional pure morphology-modified superhydrophobic coatings.

[0020] (2) This invention introduces PVDF adhesive to form a strong and tough bonding network inside the coating and at the interface between the coating and the metal substrate. The addition of PVDF significantly enhances the adhesion and resistance to mechanical damage of the coating, solving the key technical problems of poor mechanical stability and easy peeling of traditional superhydrophobic coatings. Experimental results show that after 700 sandpaper abrasion cycles and 140 tape peeling cycles, the water contact angle of the coating remains above 150°, the roll-off angle is below 2.5°, and the low-frequency impedance modulus is still nearly two orders of magnitude higher than that of the blank aluminum alloy, indicating that the coating can still maintain good corrosion protection after severe mechanical damage.

[0021] (3) The present invention uses Al 3+ A specific fluorescent probe loaded in the MXene / SiO2 composite system enables real-time, in-situ, and visualized monitoring of the corrosion process of aluminum alloys. The response mode is fluorescence enhancement, providing an effective means for early corrosion warning.

[0022] (4) The preparation process of this invention is simple, the conditions are mild and the cost is low. It is suitable for surface protection of complex-shaped metal components. The coating can be widely used in metal corrosion protection in marine engineering, aerospace, new energy equipment and other fields, and has broad application prospects. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the preparation process of the F-MXene / SiO2 / PVDF / FP multifunctional smart coating of the present invention.

[0024] Figure 2 The images shown are scanning electron microscope (SEM) images of the materials prepared in Example 1 of this invention; wherein, (a) is a Ti3C2T X (a) is a SEM image of MXene, and (b) is a SEM image of the F-MXene / SiO2 / PVDF / FP coating.

[0025] Figure 3The electrochemical test curves of the coating F-MXene / SiO2 / PVDF prepared in Example 1, the blank 6061 aluminum alloy, F-SiO2 / PVDF, and F-MXene / PVDF in 3.5wt.% NaCl solution are shown; where (a) is the Nyquist plot, (b) is the Bode plot, and (c) is the phase angle plot.

[0026] Figure 4 Electrochemical test curves of F-MXene / SiO2 / PVDF coatings prepared with different MXene to SiO2 mass ratios (1:5, 1:2, 1:1, 2:1, 5:1) in 3.5 wt.% NaCl solution; where (a) is the Nyquist plot, (b) is the Bode plot, and (c) is the phase angle plot.

[0027] Figure 5 The electrochemical test curves of the F-MXene / SiO2 / PVDF / FP coating prepared in Example 1 after mechanical damage are shown; where (a) is the Nyquist plot, (b) is the Bode plot, and (c) is the phase angle plot.

[0028] Figure 6 The curves showing the changes in wettability of the F-MXene / SiO2 / PVDF / FP coating prepared in Example 1 after mechanical damage are shown. Among them, (a) is the curve showing the changes in water contact angle and roll-off angle after a sandpaper abrasion cycle, and (b) is the curve showing the changes in water contact angle and roll-off angle after a tape peeling cycle.

[0029] Figure 7 The fluorescence monitoring results of the F-MXene / SiO2 / PVDF / FP coating prepared in Example 1 after artificial scratching and immersion in 3.5 wt.% NaCl solution are shown; where (a) is Al 3+ The fluorescence changes of the probe to different ions, (b) are fluorescence monitoring photos of the F-MXene / SiO2 / PVDF / FP coating after it was scratched and then immersed in 3.5 wt.% NaCl solution for different times. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0031] Example 1 Please see Figure 1 The preparation method of the F-MXene / SiO2 / PVDF / FP multifunctional smart coating provided in this embodiment includes the following specific steps: (1)Ti3C2T x Preparation of MXene: In a polytetrafluoroethylene (PTFE) beaker, 10 mL of 9 mol / L HCl solution was added, followed by slow addition of 0.6 g of LiF powder. The mixture was magnetically stirred for 10 min until completely dissolved, forming a homogeneous and transparent etching solution. The beaker was then placed in an ice-water bath at 0-5℃, and 0.5 g of Ti3AlC2 powder was slowly added. After the powder was completely dispersed, the mixture was transferred to an oil bath at 40℃ and continuously magnetically stirred for 48 h. After the reaction was complete, 50 mL of distilled water was added to the product, and the mixture was centrifuged at 3500 r / min for 10 min. The supernatant was discarded. The centrifugation-washing operation was repeated until the pH of the supernatant was >6, and the lower black precipitate was collected. The precipitate was placed in a freeze dryer and freeze-dried at -50℃ for 12 h to obtain multilayer Ti3C2T. x MXene powder.

[0032] (2) Preparation of F-MXene / SiO2 / PVDF materials: Measure 11 mL of anhydrous ethanol and 1.5 mL of 25% ammonia solution and mix well. Add 0.2 mL of TEOS and stir magnetically for 30 min. Add 0.15 g of MXene and 0.15 g of SiO2 nanoparticles and continue stirring at room temperature for 1 h. Then add 0.2 mL of PFDTES and 1 g of PVDF in sequence. First, stir ultrasonically for 30 min, and then stir magnetically for 60 min to obtain a uniform and stable F-MXene / SiO2 / PVDF suspension.

[0033] (3) Preparation of F-MXene / SiO2 / PVDF coating and F-MXene / SiO2 / PVDF / FP multifunctional smart coating: At 60℃, 1g of PVDF was dissolved in 20mL of DMF solution to obtain a PVDF DMF solution; then, the above F-MXene / SiO2 / PVDF suspension was taken and 8-hydroxyquinoline was added at a mass ratio of 100:1. The mixture was stirred at room temperature for 1h to obtain a uniform F-MXene / SiO2 / PVDF / FP mixture; a 6061 aluminum alloy substrate with a size of 25mm×10mm×1mm was polished sequentially with 800-grit, 1000-grit, and 2000-grit sandpaper, then ultrasonically cleaned in ethanol and acetone for 10min, and dried at 60℃ for 30min to obtain a pretreated 6061 aluminum alloy substrate.

[0034] The pretreated 6061 aluminum alloy substrate was vertically immersed in a PVDF DMF solution, then immediately immersed in an F-MXene / SiO2 / PVDF suspension. After holding for 3 seconds, it was slowly lifted out at a speed of 5 mm / s, left at room temperature for 5 minutes, and then transferred to a 60℃ forced-air drying oven for curing for 12 hours to obtain a product without identified Al. 3+ The probe is coated with F-MXene / SiO2 / PVDF.

[0035] The pretreated 6061 aluminum alloy substrate was vertically immersed in the DMF solution of PVDF, and then immediately immersed in the F-MXene / SiO2 / PVDF / FP mixture. After 3 seconds, it was slowly lifted out at a speed of 5 mm / s, placed at room temperature for 5 minutes, and then transferred to a 60℃ forced-air drying oven for curing for 12 hours to obtain the F-MXene / SiO2 / PVDF multifunctional smart coating.

[0036] Comparative Example 1 The preparation method of the F-MXene / SiO2 / PVDF coating in Example 1 is basically the same, except that MXene is not added, and only 0.3g of SiO2 is used to replace the mixture of MXene and SiO2. The remaining steps are the same to obtain the F-SiO2 / PVDF coating.

[0037] Comparative Example 2 The preparation method of the F-MXene / SiO2 / PVDF coating in Example 1 is basically the same, except that SiO2 is not added, and only 0.3g of MXene is used to replace the mixture of MXene and SiO2. The remaining steps are the same to obtain the F-MXene / PVDF coating.

[0038] Comparative Example 3 The preparation method of F-MXene / SiO2 / PVDF coating is basically the same as that of Example 1, except that the amount of MXene and SiO2 added is adjusted. At this time, the ratio of the amount of MXene and SiO2 added is 0.05g:0.25g, and F-MXene / SiO2 / PVDF coatings with different MXene contents are obtained.

[0039] Comparative Example 4 The preparation method of F-MXene / SiO2 / PVDF coating is basically the same as that of Example 1, except that the amount of MXene and SiO2 added is adjusted. At this time, the ratio of the amount of MXene and SiO2 added is 0.1 g: 0.2 g, and F-MXene / SiO2 / PVDF coatings with different MXene contents are obtained.

[0040] Comparative Example 5 The preparation method of F-MXene / SiO2 / PVDF coating is basically the same as that of Example 1, except that the amount of MXene and SiO2 added is adjusted. At this time, the ratio of the amount of MXene and SiO2 added is 0.2g:0.1g, and F-MXene / SiO2 / PVDF coatings with different MXene contents are obtained.

[0041] Comparative Example 6 The preparation method of F-MXene / SiO2 / PVDF coating is basically the same as that of Example 1, except that the amount of MXene and SiO2 added is adjusted. At this time, the ratio of the amount of MXene and SiO2 added is 0.25g:0.05g, and F-MXene / SiO2 / PVDF coatings with different MXene contents are obtained.

[0042] The water contact angle and roll-off angle of the F-MXene / SiO2 / PVDF coating in Example 1 and the coatings prepared in Comparative Examples 1-6 were tested. The specific test results are shown in Table 1.

[0043] Table 1 Water contact angle and roll-off angle for different coatings

[0044] As shown in Table 1, the water contact angle of Comparative Example 2 is relatively low, indicating that SiO2 nanoparticles play an important role in constructing micro-nano rough structures and improving superhydrophobic properties.

[0045] Please see Figure 2 , Figure 2 (a) Ti3C2T prepared in Example 1 x MXene's scanning electron microscope (SEM) images clearly show Ti3C2T x MXene exhibits a typical accordion-like multilayered structure. Figure 2 (b) is a scanning electron microscope (SEM) image of the F-MXene / SiO2 / PVDF / FP multifunctional smart coating prepared in Example 1, clearly showing Ti3C2T x The micro-nano hierarchical rough structure is composed of MXene two-dimensional sheets and SiO2 nanoparticles, with SiO2 nanoparticles uniformly distributed on Ti3C2T. x The MXene sheet surface and interlayer together construct a composite structure with multi-level roughness.

[0046] Figure 3 Electrochemical test curves of blank 6061 aluminum alloy, F-SiO2 / PVDF, F-MXene / PVDF and F-MXene / SiO2 / PVDF coating in 3.5wt.% NaCl solution are compared. Figure 3 (a) shows the Nyquist curve. The F-MXene / SiO2 / PVDF coating has the largest Nyquist arc radius and the best corrosion resistance. In contrast, the blank 6061 aluminum alloy has the smallest Nyquist arc radius and the worst corrosion resistance. Figure 3 (b) is the Bode plot, showing the low-frequency impedance modulus (|Z|) of the F-MXene / SiO2 / PVDF coating. 0.01Hz The value reached 4.22 × 104 Ω·cm 2 Compared to blank 6061 aluminum alloy (2.18×10), 3 Ω·cm 2 This represents an improvement of more than one order of magnitude. The low-frequency impedance modulus of the F-MXene / PVDF coating is 8.91 × 10⁻⁶. 3 Ω·cm 2 The F-SiO2 / PVDF coating has a strength of 5.01 × 10⁻⁶. 3 Ω·cm 2 Both are significantly lower than those of F-MXene / SiO2 / PVDF coatings. Figure 3 (c) shows the phase angle diagram. The peak phase angle of the F-MXene / SiO2 / PVDF coating in the mid-to-high frequency region is close to 80° with a broad and gentle peak shape, indicating that the coating has excellent capacitance characteristics and complete structural integrity, and can continuously suppress electrolyte permeation. In contrast, the phase angle of the blank aluminum alloy drops rapidly in the mid-to-high frequency region, indicating that its surface has no protective layer, and the corrosive medium directly contacts the metal surface. The above performance advantages stem from the physical barrier effect provided by the two-dimensional sheet structure of MXene, the additional barrier formed by the air layer trapped by the superhydrophobic surface, and the strong interfacial bonding between the low surface energy characteristics after fluorination modification and the metal substrate.

[0047] Figure 4 Electrochemical test curves of F-MXene / SiO2 / PVDF coatings prepared with different MXene to SiO2 mass ratios (1:5, 1:2, 1:1, 2:1, 5:1) on 6061 aluminum alloy substrates were compared to investigate the effect of different MXene contents on corrosion resistance. The tested ratios included: 0.05:0.25 (1:5), 0.1:0.2 (1:2), 0.15:0.15 (1:1), 0.2:0.1 (2:1), and 0.25:0.05 (5:1). Figure 4 (a) is the Nyquist plot. When the MXene / SiO2 mass ratio is 1:1, the Nyquist arc radius is the largest, indicating that the coating with this ratio has the highest charge transfer resistance and the best corrosion resistance. When the MXene content is too low (1:5) or too high (5:1), the Nyquist arc radius decreases significantly. Figure 4 (b) shows the Bode plot. When the MXene / SiO2 mass ratio is 1:1, its low-frequency impedance modulus reaches 1.78 × 10⁻⁶. 5 Ω·cm 2 It is the highest among all the proportions. Figure 4(c) shows the phase angle diagram. The coating with an MXene / SiO2 mass ratio of 1:1 exhibits the highest peak phase angle and the broadest peak shape in the mid-to-high frequency region, indicating that its coating structure is the most complete and dense. The coatings with ratios of 1:5 and 5:1 have lower peak phase angles and narrower peak shapes, indicating structural defects in the coatings. These results are attributed to the optimal balance of synergistic effects between MXene and SiO2 when the MXene / SiO2 mass ratio is 1:1. The two-dimensional sheets of MXene provide a physical barrier, while SiO2 nanoparticles fill the gaps between the sheets and enhance surface roughness, together constructing a dense micro-nano composite structure. When the MXene content is too low (e.g., 1:5), the coating is not dense enough, and corrosive media can easily penetrate through the pores between SiO2 particles; when the MXene content is too high (e.g., 5:1), the MXene sheets are prone to agglomeration and stacking, leading to structural defects and reducing the protective effect.

[0048] Figure 5 The electrochemical test curves of the F-MXene / SiO2 / PVDF / FP coating prepared in Example 1 after undergoing different cycles of sandpaper abrasion and tape peeling demonstrate that it still maintains good anti-corrosion performance after mechanical damage. Figure 5 (a) is the Nyquist plot. After 700 sandpaper abrasion cycles, the Nyquist arc radius of the coating decreased slightly but still maintained a large arc. After 140 tape peeling cycles, the Nyquist arc radius also maintained a large arc, indicating that the charge transfer resistance of the coating was still high after mechanical damage. Figure 5 (b) is the Bode plot, showing that the low-frequency impedance modulus of the coating after mechanical damage decreased from the original value of 4.22 × 10⁻⁶. 4 Ω·cm 2 They remained at 4.39×10 4 Ω·cm 2 (After 700 sandpaper passes) and 3.67×10 4 Ω·cm 2 (After 140 tape peels), it still has a lower low-frequency impedance modulus than blank 6061 aluminum alloy (2.18 × 10⁻⁶). 3 Ω·cm 2 It is one order of magnitude higher. Figure 5(c) shows the phase angle diagram. After mechanical damage, the peak phase angle of the coating in the mid-to-high frequency region remains above 70°, and the peak shape is still broad and gentle, indicating that although the coating structure is damaged to some extent, it still maintains good integrity and barrier performance. The above results show that the F-MXene / SiO2 / PVDF / FP coating can still maintain good corrosion protection ability after experiencing severe mechanical damage. This is because the strong adsorption and coordination between MXene, SiO2, the binder PVDF, and the metal substrate makes it difficult for the coating to completely detach from the substrate after mechanical damage. The remaining coating structure can form a discontinuous but effective protective barrier. At the same time, the excellent chemical stability and two-dimensional lamellar structure of MXene can still play a protective role by extending the penetration path of corrosive media, even when the surface is damaged.

[0049] Figure 6 The curves show the changes in water contact angle and roll-off angle of the F-MXene / SiO2 / PVDF / FP coating prepared in Example 1 after undergoing different cycles of sandpaper abrasion and tape peeling. Figure 6 (a) The curves showing the changes in water contact angle and roll-off angle after 700 sandpaper abrasion cycles. As the number of sandpaper abrasion cycles increases, the water contact angle gradually decreases, while the roll-off angle gradually increases. Even after 700 abrasion cycles, the coating remains superhydrophobic (contact angle > 150°, roll-off angle < 5°). Figure 6 (b) shows the changes in water contact angle and roll-off angle after 140 tape peeling cycles. With increasing tape peeling cycles, the water contact angle gradually decreases, while the roll-off angle gradually increases. Even after 140 peeling cycles, the coating remains superhydrophobic. These results indicate that the coating exhibits good mechanical stability. Although some micro / nano structures on the surface are damaged after sandpaper abrasion or tape peeling, the internal micro / nano binary structures of the coating are re-exposed. The newly exposed surface continues to provide sufficient roughness and low surface energy, thus enabling the coating to maintain its superhydrophobic properties even during continuous mechanical damage.

[0050] Figure 7 The images show fluorescence monitoring of the F-MXene / SiO2 / PVDF / FP coating of Example 1 after it was artificially scratched and then immersed in 3.5 wt.% NaCl solution for different times, demonstrating the fluorescence enhancement process. Figure 7 (a) indicates that Al 3+ Fluorescent probes for Al 3 + Fluorescence changes that exhibit specific recognition; Figure 7 (b) indicates that for the addition of Al 3+ The coating of the fluorescent probe does not fluoresce under ultraviolet light. However, with increasing immersion time, the coating containing Al... 3+The fluorescence intensity of the fluorescent probe coating gradually increased, eventually reaching a strong fluorescence intensity after immersion in 3.5 wt.% NaCl solution for 10 days. This fluorescence originates from Al. 3+ Fluorescent groups and metal corrosion at defect interfaces can produce Al. 3+ Furthermore, the fluorescent group and the specific Al-based 3+ Ion recognition enables fluorescence enhancement. For deeper scratches, the 6061 aluminum alloy substrate is directly exposed to the corrosive medium, leading to an electrochemical corrosion reaction at the metal-coating interface. In this case, the fluorescent probe targets the Al... 3+ The presence of Al is specifically identified and associated with Al 3+ The combination of these elements leads to enhanced fluorescence, while the undamaged areas of the coating remain superhydrophobic, effectively preventing electrolyte penetration and thus enabling real-time corrosion monitoring of 6061 aluminum alloy. Therefore, dynamic corrosion monitoring of coatings containing F-MXene / SiO2 / PVDF / FP superhydrophobic coatings can be achieved through fluorescence response behavior.

[0051] The above description is a preferred embodiment of the present invention, used to explain the technical solution of the present invention, and is not intended to limit the present invention. Those skilled in the art can make conventional modifications, equivalent substitutions and improvements within the spirit and principles of the present invention, all of which are still included within the protection scope of the present invention.

Claims

1. A method for preparing an F-MXene / SiO2 / PVDF / FP multifunctional smart coating, characterized in that, Includes the following steps: (1) Preparation of F-MXene / SiO2 / PVDF materials: Anhydrous ethanol and 25% ammonia solution were mixed evenly, MXene and SiO2 nanoparticles were added, followed by TEOS, and the mixture was stirred at room temperature. Then PFDTES and PVDF were added sequentially, and the mixture was first ultrasonically stirred and then magnetically stirred to obtain a uniform and stable F-MXene / SiO2 / PVDF suspension. (2) Preparation of F-MXene / SiO2 / PVDF / FP multifunctional smart coating: The obtained F-MXene / SiO2 / PVDF suspension was reacted with Al 3+ Fluorescent probes are mixed evenly to obtain a mixed solution of F-MXene / SiO2 / PVDF / FP. After pretreatment of the aluminum alloy substrate, it is coated with DMF solution of PVDF and the mixed solution of F-MXene / SiO2 / PVDF / FP in sequence, and then dried and cured to obtain the multifunctional smart coating of F-MXene / SiO2 / PVDF / FP.

2. The method for preparing an F-MXene / SiO2 / PVDF / FP multifunctional smart coating according to claim 1, characterized in that: In step (1), the MXene is Ti3C2T x MXene, Ti3C2T x The preparation method of MXene is as follows: LiF powder is slowly added to HCl solution and stirred until completely dissolved to form a homogeneous and transparent etching solution; the container containing the etching solution is placed in an ice-water bath, and Ti3AlC2 powder is slowly added. After the powder is completely dispersed, it is transferred to an oil bath and the reaction is continuously magnetically stirred; after the reaction is completed, the mixture is centrifuged and washed several times until the pH of the supernatant is >6, and the lower black precipitate is collected; the precipitate is freeze-dried to obtain Ti3C2T x MXene powder.

3. The method for preparing an F-MXene / SiO2 / PVDF / FP multifunctional smart coating according to claim 2, characterized in that: The ratio of LiF, Ti3AlC2 and HCl solution used is 0.6 g: 0.5 g: 10 mL; the concentration of HCl solution is 9 mol / L; the temperature of the ice-water bath is controlled at 0-5℃; the temperature of the oil bath is controlled at 40℃; the stirring time is 48 h; and the freeze-drying temperature is -50℃ for 12 h.

4. The method for preparing an F-MXene / SiO2 / PVDF / FP multifunctional smart coating according to claim 1, characterized in that: In step (1), the ratio of the amounts of MXene, SiO2, anhydrous ethanol, ammonia, TEOS, PVDF and PFDTES is 0.15g:0.15g:11mL:1.5mL:0.25mL:1g:0.2mL.

5. The method for preparing an F-MXene / SiO2 / PVDF / FP multifunctional smart coating according to claim 1, characterized in that: In step (2), the F-MXene / SiO2 / PVDF suspension and Al 3+ The mass ratio of the fluorescent probe is 100:

1.

6. The method for preparing an F-MXene / SiO2 / PVDF / FP multifunctional smart coating according to claim 1, characterized in that: In step (2), the Al 3+ The fluorescent probe is 8-hydroxyquinoline, with an excitation wavelength of 365 nm and an emission wavelength of 450 nm.

7. The method for preparing an F-MXene / SiO2 / PVDF / FP multifunctional smart coating according to claim 1, characterized in that: In step (2), the pretreatment method of the aluminum alloy substrate is as follows: the aluminum alloy substrate is polished with 800-grit, 1000-grit and 2000-grit sandpaper in sequence until the surface is flat to remove the oxide layer, and then ultrasonically cleaned in anhydrous ethanol and acetone for 10 min each, and dried at 60°C for 30 min for later use.

8. The method for preparing an F-MXene / SiO2 / PVDF / FP multifunctional smart coating according to claim 1, characterized in that: In step (2), the method for preparing the PVDF DMF solution is as follows: dissolve PVDF in DMF, heat in an oil bath at 60°C and stir for 30 min to obtain the solution; wherein, the ratio of PVDF to DMF is 1g:20mL.

9. The F-MXene / SiO2 / PVDF / FP multifunctional smart coating prepared by the method according to any one of claims 1-8, wherein the coating has Ti3C2T x A composite micro / nano hierarchical rough structure of MXene two-dimensional sheets and SiO2 nanoparticles modified with PFDTES, with PVDF forming a flexible bonding network, and Al 3+ The specific fluorescent probe is uniformly dispersed within it.

10. The application of the F-MXene / SiO2 / PVDF / FP multifunctional smart coating as described in claim 9 in the corrosion protection of aluminum alloys.

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