Metal surface wave-absorbing and corrosion-preventing function integrated coating and preparation method

Abstract

The application relates to a metal surface wave-absorbing and corrosion-preventing function integrated coating and a preparation method, in particular to the following steps: first, magnetic modification of porous boron nitride nanosheets (BNNS), growth of polyaniline nanoparticles on the BNNS, directional arrangement of PANI-CFBN through a magnetic field, and finally coating of TiO2 nanoparticles to obtain a wave-absorbing and corrosion-preventing function coating. The wave-absorbing and corrosion-preventing function coating with a lotus leaf-shaped microstructure prepared by the application is modified through porous boron nitride nanosheets, polyaniline nanoparticles are grown on the porous boron nitride nanosheets, an electromagnetic wave absorption layer is formed, and additional interfaces are provided to enhance absorption and scattering. The directional arrangement of PANI-CFBN through a magnetic field improves the electromagnetic wave dissipation capacity, TiO2 nanoparticles are added to improve the dielectric constant of the material and improve the wave-absorbing capacity. The conductivity of polyaniline and the chemical stability of boron nitride jointly improve the corrosion-preventing performance of the material. In addition, the addition of modified TiO2 nanoparticles constructs a unique lotus leaf-shaped microstructure and improves the hydrophobicity of the material.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of functional composite materials, and relates to an integrated coating with wave-absorbing and corrosion-resistant functions on a metal surface and a preparation method thereof. Background Art

[0002] In the 21st century, the widespread use of electronics and microwave technologies has led to electromagnetic radiation pollution, posing a threat to human health and the proper operation of precision electronic equipment. Long-term exposure to electromagnetic waves can cause health problems and even cancer. In the military, advances in radar technology have increased the risk of electromagnetic detection and attack on traditional military equipment. Consequently, there is a growing demand for absorbing materials that can reduce the radar cross-section of military targets and improve their concealment. However, existing absorbing materials often lack the necessary corrosion resistance when used outdoors or in extreme environments, making them susceptible to corrosion by chemicals such as salt spray, acids, and alkalis, limiting their service life and scope of application.

[0003] Traditional materials struggle to achieve both high absorption and corrosion resistance. Boron nitride and polyaniline, due to their unique physical and chemical properties, are increasingly being researched for their applications in these areas. When used alone, these materials struggle to meet high-performance requirements for absorption and corrosion resistance. However, surface modification or compounding with other materials can significantly improve their absorption and corrosion resistance. However, the tendency of these materials to agglomerate severely limits the performance of the composites. Therefore, researching and developing new functional composite materials that possess both efficient electromagnetic wave absorption and excellent corrosion resistance is of strategic importance for reducing electromagnetic pollution, protecting human health, and improving the concealment and protective capabilities of military equipment.

[0004] The Chinese patent "A silicon nitride-silicon carbide porous ceramic absorbing material and its preparation method" (application number: CN202111550760.6, authorization number: CN114262230B, announcement date: 2022-12-13) discloses a preparation method of a silicon nitride-silicon carbide porous ceramic absorbing material. The porous material allows electromagnetic waves to be reflected on the surface of the material, and more electromagnetic waves can enter the interior of the material and be absorbed and attenuated. However, there is a problem of a relatively single absorption mechanism, and there is still much room for improvement in improving the absorption performance.

[0005] The Chinese patent "Preparation method of TiO2-coated carbonyl iron modified anti-corrosion and wave-absorbing composite material and its application in anti-corrosion and wave-absorbing coating" (application number: CN202410641098.2, authorization number: CN118496703A, announcement date: 2024.08.16) discloses a preparation method of TiO2-coated carbonyl iron modified anti-corrosion and wave-absorbing composite material and its application in anti-corrosion and wave-absorbing coating. Carbonyl iron is coated with TiO2 to obtain CIP@TiO2 powder. This material has excellent wave-absorbing properties, but due to the coating structure, the dispersibility is limited, which limits the wave-absorbing and anti-corrosion properties of the coating.

[0006] The Chinese patent "A polyaniline nanocomposite material for anti-corrosion coatings and its preparation method, a polyaniline composite anti-corrosion coating" (application number: CN202311674116.9, authorization number: CN117659758A, announcement date: 2024.03.08) discloses a polyaniline nanocomposite material for anti-corrosion coatings and its preparation method. Polyaniline is in situ polymerized on graphene nanosheets, avoiding material agglomeration and optimizing the structure, but the material has a relatively single function.

[0007] The Chinese patent "A heat-resistant and corrosion-resistant resin-based absorbing coating and its preparation method" (application number: CN202411177087.X, authorization number: CN119039821A, announcement date: 2024.11.29) discloses a heat-resistant and corrosion-resistant resin-based absorbing coating and its preparation method. An absorbing agent is mixed with a resin slurry to obtain an absorbing coating, which is sprayed on the surface of a substrate and cured to obtain a heat-resistant and corrosion-resistant resin-based absorbing coating. The coating has good anti-corrosion and absorbing properties, but the material has a single absorbing mechanism and limited corrosion resistance, which limits the application of the coating.

[0008] The Chinese patent "A zinc oxide / titanium dioxide / titanium carbide composite absorbing material and its preparation method" (application number: CN202310252776.1, authorization number: CN116333683A, announcement date: 2023.06.27) discloses a zinc oxide / titanium dioxide / titanium carbide composite absorbing material and its preparation method. x The zinc oxide / titanium dioxide / titanium carbide composite absorber is obtained by reacting it with Zn(CH3COO)2·2H2O in an autoclave and heat-treating it in a tube furnace under an argon atmosphere. However, the cost of this material is too high and its production is limited. Summary of the Invention

[0009] The purpose of the present invention is to provide a metal surface coating with integrated wave absorbing and anti-corrosion functions and a preparation method thereof, which solves the problem of applying electromagnetic wave absorption technology in extreme environments.

[0010] The present invention adopts two technical solutions:

[0011] The first aspect adopts an integrated coating with microwave absorption and anti-corrosion functions on the metal surface, including: a lotus-shaped PANI-CFBN@TiO2 casting liquid formed by a directional arranged PANI-CFBN composite material and modified TiO2 nanoparticles. The casting liquid is attached to the metal surface by spin coating.

[0012] The second aspect adopts a metal surface coating with integrated microwave absorption and corrosion protection functions and a preparation method, comprising the following steps:

[0013] Step 1: Preparation of porous BNNS

[0014] Boric acid and urea were dissolved in ultrapure water, heated and stirred, filtered and dried, and then dispersed in water. Phosphoric acid was added, stirred evenly, dried, and calcined in a horizontal tube furnace to obtain porous BNNS.

[0015] Step 2: Magnetic modification of porous BNNS

[0016] The porous BNNS prepared in step 1 was dispersed in deionized water, and Co(NO3)2·6H2O and FeSO4·7H2O were dispersed in a mixture of water and ethylene glycol (EG). The mixture was evenly mixed with the porous BNNS aqueous solution and ammonia was added to react. After drying, CoFe2O4-BNNS (CFBN) was obtained.

[0017] Step 3: Oriented alignment of PANI-CFBN composites

[0018] The CoFe2O4-BNNS obtained in step 2 was dispersed in deionized water, aniline and acidic solution were added, and after stirring evenly, ammonium sulfate (APS) mixed with acidic solution was added. A pulsed magnetic field coil was installed on the outside of the beaker, and the mixture was stirred in an ice bath for 12 hours. After standing, the mixture was washed and vacuum dried to obtain polyaniline / boron nitride composite nanomaterials (PANI-CFBN).

[0019] Step 4: Preparation of modified TiO2 nanoparticles

[0020] TiO2 is added into a mixed solution of anhydrous ethanol and deionized water, and concentrated ammonia is used to adjust the pH value; a coupling agent is added and stirred, aged at room temperature, and filtered and dried to obtain modified TiO2 nanoparticles.

[0021] Step 5: Constructing lotus-shaped PANI-CFBN@TiO2

[0022] The nanofillers prepared in steps three and four are dispersed in an organic solution, polyvinylidene fluoride (PVDF) powder is added, and the mixture is alternately stirred and ultrasonically treated. After standing, a uniform lotus-shaped PANI-CFBN@TiO2 casting solution is obtained.

[0023] Step 6: Preparation of PVDF-based PANI-CFBN@TiO2 coating

[0024] The casting solution obtained in step five is spin-coated on the metal surface using a spin coater to form a coating, and then dried to obtain an integrated coating with microwave absorbing and anti-corrosion functions.

[0025] The present invention is also characterized in that:

[0026] In step 1, the molar ratio of uric acid to boric acid is 1:2-2:1, the storage temperature is 80-100°C, the time is 2-3 hours, the molar ratio of urea borate precursor to phosphoric acid is 1:1, the stirring time at room temperature is 8-12 hours, and the mixture is heated to 1100°C at a rate of 5°C / min in a horizontal tube furnace for 4-6 hours.

[0027] In step 2, the amount of porous BNNS material is 0.01-0.02 mol, deionized water is 40-80 mL, the molar ratio of Co(NO3)2·6H2O and FeSO4·7H2O is 1:2, the volume ratio of the mixture of water and ethylene glycol (EG) is 1:3, the volume of the mixture is 40-80 mL, the ultrasonic stirring time is 30-60 min, the ammonia water is 4-6 mL, the high-pressure reaction temperature is 180-200°C, and the reaction time is 24 h.

[0028] The acidic solution in step 3 is either hydrochloric acid or sulfuric acid, with a concentration of 1.5 mol / L. The concentration of aniline in the acidic solution is 0.006 g / mL to 0.012 g / mL, the concentration of CFBN in deionized water is 0.005 g / mL to 0.01 g / mL, and the volume ratio of deionized water to the acidic solution is 1:5. The stirring time is 4-6 hours, the concentration of APS in the acidic solution is 0.225 g / mL to 0.3 g / mL, and the mass ratio of APS to CFBN is 6:1 to 9:1. The pulsed magnetic field coil is adjusted to a frequency of 50 Hz, an induction power of 2.2 kW to 12 kW, and the direction of the magnetic field is parallel to the bottom of the beaker.

[0029] In step 4, the volume ratio of anhydrous ethanol and deionized water is 1:1, the pH is adjusted to 9, the mass ratio of TiO2 and coupling agent (KH570) is 30:1 to 40:1, the concentration of TiO2 in the mixed solution of anhydrous ethanol and deionized water is 0.2 g / mL to 0.3 g / mL, and the aging time at room temperature is 20-30 minutes.

[0030] The organic solution in step five is N-dimethylformamide (DMF), the mass ratio of PANI-CFBN, TiO2, and PVDF is 2:1:2-4:1:4, and the concentration of PANI-CFBN in DMF is 0.15 g / mL to 0.3 g / mL.

[0031] The drying temperature in step 6 is 120°C for 18-24 hours. The spin coater speed is set to 800-1000 rpm for 5 seconds, and the casting solution is 1.5-2 mL.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] A functional composite material combining efficient electromagnetic wave absorption and excellent corrosion resistance can be obtained. The porous boron nitride nanosheets are modified, and polyaniline nanoparticles are grown on them to form an electromagnetic wave absorption layer, while also providing an additional interface to enhance absorption and scattering. The PANI-CFBN is aligned in a magnetic field, further optimizing the structure and improving the electromagnetic wave dissipation capacity. The addition of TiO2 nanoparticles increases the material's dielectric constant and improves its wave absorption capacity. The electrical conductivity of polyaniline and the chemical stability of boron nitride combine to enhance the material's corrosion resistance. Furthermore, the addition of modified TiO2 nanoparticles creates a unique lotus leaf-like microstructure, enhancing the material's hydrophobicity. This material excels in reducing electromagnetic pollution and improving military concealment, while being environmentally friendly and possessing broad application potential, portending significant economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of the microscopic morphology of the PVDF-based PANI-CFBN@TiO2 coating prepared by the present invention.

[0035] In the figure, 1-TiO2 nanoparticles, 2-polyaniline nanoparticles, 3-BNNS. DETAILED DESCRIPTION

[0036] The technical solution adopted by the present invention is a method for preparing an integrated material with wave-absorbing and anti-corrosion functions, comprising the following steps:

[0037] Step 1: Preparation of porous BNNS

[0038] Urea and boric acid are dissolved in 100-200 ml of ultrapure water at a molar ratio of 1:2-2:1, stored at 80-100°C for 2-3 hours, cooled naturally, and filtered and dried to obtain a uric acid borate precursor (M·2B). M·2B is then dispersed in water, and phosphoric acid is added at a molar ratio of 1:1 to M·2B. The mixture is stirred at room temperature for 8-12 hours, and filtered and dried to obtain a white M·2B·P precursor. The M·2B·P precursor is then placed in a horizontal tube furnace, purged with nitrogen, and heated to 1100°C at a rate of 5°C / min. The mixture is then held at this temperature for 4-6 hours to obtain loose, porous BNNS.

[0039] Step 2: Magnetic modification of porous BNNS

[0040] 0.01-0.02 mol of BNNS was dispersed in 40-80 mL of water. Simultaneously, Co(NO₃)₂·6H₂O and FeSO₄·7H₂O were dispersed in a 1:2 molar ratio in 40-80 mL of a mixture of water and ethylene glycol (EG) (water:EG ratio 1:3 by volume) and ultrasonically stirred for 30-60 minutes to obtain Solution A. The porous BNNS solution was added to Solution A and stirred until uniform. Afterwards, 4-6 mL of aqueous ammonia was added and stirred for 1-2 hours. The reaction was then carried out at high pressure at 180-200°C for 24 hours. After the reaction was complete, the high-pressure steam was cooled to room temperature. The resulting precipitate was filtered, washed three times with deionized water and ethanol, and dried to obtain CoFe₂O₄-BNNS (CFBN).

[0041] Step 3: Oriented alignment of PANI-CFBN composites

[0042] Add aniline to a 1.5 mol / L acidic (hydrochloric acid, sulfuric acid) solution at a concentration of 0.006 g / mL to 0.012 g / mL and stir until uniform. Add the CoFe2O4-BNNS obtained in step 2 to deionized water at a concentration of 0.005 g / mL to 0.01 g / mL, with a volume ratio of deionized water to acidic solution of 1:5. After ultrasonic dispersion, add the mixture to the aniline solution and stir for 4-6 hours. Add APS to an acidic (hydrochloric acid, sulfuric acid) solution at a concentration of 0.225 g / mL to 0.3 g / mL, with a mass ratio of APS to CFBN of 6:1 to 9:1. After stirring evenly, it was added dropwise into the first solution. Subsequently, a pulsed magnetic field coil was installed on the outside of the beaker and the frequency was adjusted to 50 Hz. The induction power was 2.2 kW to 12 kW. The direction of the magnetic field was parallel to the bottom of the beaker. After stirring in an ice bath for 12 hours, it was allowed to stand, washed with deionized water and ethanol 5 times each, and vacuum dried at 80°C for 24 hours to obtain polyaniline / boron nitride composite nanomaterials (PANI-CFBN).

[0043] Step 4: Preparation of modified TiO2 nanoparticles

[0044] A mixed solution was prepared by mixing anhydrous ethanol and deionized water in a volume ratio of 1:1, and the pH was adjusted to 9 with concentrated ammonia water; TiO2 was added thereto at a concentration of 0.2 g / mL to 0.3 g / mL, ultrasonically dispersed for 10 minutes, and stirred at 80°C for 20 minutes; KH-570 was added with a mass ratio of TiO2 to coupling agent (KH570) of 30:1 to 40:1, stirred for 1.5 hours, aged at room temperature for 20-30 minutes, and filtered and dried to obtain modified TiO2.

[0045] Step 5: Constructing lotus-shaped PANI-CFBN@TiO2

[0046] The nanofillers PANI-CFBN and modified TiO2 from steps three and four are added to the organic solution DMF, and a stable suspension is obtained after ultrasonic dispersion. Then, polyvinylidene fluoride (PVDF) powder is added to the suspension, wherein the mass ratio of PANI-CFBN, TiO2, and PVDF is 2:1:2-4:1:4, and the concentration of PANI-CFBN in DMF is 0.15 g / mL~0.3 g / mL. Magnetic stirring and ultrasonic treatment are used alternately, and then the mixture is allowed to stand to obtain a uniform lotus-shaped PANI-CFBN@TiO2 casting solution.

[0047] Step 6: Preparation of PVDF-based PANI-CFBN@TiO2 coating

[0048] The resulting uniform casting solution was spin-coated onto the metal surface using a spin coater at 800-1000 rpm for 5-8 seconds, using 1.5-2.0 mL of casting solution. The coating was then dried at 120°C for 18-24 hours to obtain an integrated coating with microwave-absorbing and corrosion-resistant properties.

[0049] The present invention magnetically modifies porous boron nitride nanosheets, controlling parameters to increase the electromagnetic wave magnetic loss mechanism and enhance wave absorption. By controlling the magnetic field, the modified porous BNNS loaded with polyaniline nanoparticles are oriented, resulting in improved conductivity in the doped state of polyaniline. This can inhibit corrosion through electron transfer, while forming a stable electromagnetic wave absorption layer and providing an additional interface to enhance absorption and scattering. TiO2 nanoparticles are modified with a coupling agent and coated on the PANI-CFB N surface to construct a composite material with a lotus leaf-like micromorphology, improving the material's hydrophobicity. Boron nitride has excellent chemical stability and, when combined with polyaniline and modified TiO2, can form a composite material with a synergistic effect, optimizing the material's corrosion resistance and dielectric constant. A coating is prepared using PVDF as the matrix, and the interfacial bonding of the coating is further enhanced by controlling the filler content.

[0050] The present invention modifies porous boron nitride nanosheets and grows polyaniline nanoparticles on them to form an electromagnetic wave absorption layer, while also providing additional interfaces to enhance absorption and scattering. By aligning the PANI-CFBN in a magnetic field, the structure is further optimized, improving the electromagnetic wave dissipation capacity. The addition of TiO2 nanoparticles simultaneously increases the material's dielectric constant and improves its wave absorption capacity. The electrical conductivity of polyaniline and the chemical stability of boron nitride combine to enhance the material's corrosion resistance. Furthermore, the addition of modified TiO2 nanoparticles creates a unique lotus leaf-like microstructure, enhancing the material's hydrophobicity. This material excels in reducing electromagnetic pollution and improving military concealment, while also being environmentally friendly and possessing broad application potential, potentially promising significant economic and social benefits.

[0051] Example 1 Preparation of PVDF-based PANI-CFBN coating

[0052] First, urea (0.6 g) and boric acid (1.24 g) were dissolved in 200 ml of ultrapure water, stored at 80°C for 2 hours, cooled to room temperature, and filtered and dried to obtain a urea borate precursor (M·2B). This was then dispersed in water, 1 g of phosphoric acid was added, stirred at room temperature for 8 hours, and filtered and dried to obtain a white M·2B·P precursor. The M·2B·P precursor was placed in a horizontal tube furnace, purged with nitrogen, and heated to 1100°C at a rate of 5°C / min. The temperature was maintained for 4 hours to obtain loose, porous BNNS.

[0053] 0.24 g of porous BNNS was dispersed in 40 mL of water. Simultaneously, 0.29 g of Co(NO₃)₂·6H₂O and 0.28 g of FeSO₄·7H₂O were dispersed in 40 mL of a mixture of water and ethylene glycol (EG) (water:ethylene glycol = 1:3) and stirred to obtain Solution A. The porous BNNS solution was added to Solution A and stirred to obtain a uniform mixture. Afterwards, 4 mL of ammonia was added and stirred for 1 hour. The mixture was then reacted at 180°C under high pressure for 24 hours. After the reaction was complete, the high-pressure steam was cooled to room temperature. The resulting precipitate was filtered, washed five times with deionized water and ethanol, and dried at 60°C to obtain CoFe₂O₄-BNNS.

[0054] 3g of aniline was added to 500mL of 1.5mol / L sulfuric acid solution and stirred. 1g of CoFe2O4-BNNS was added to 100mL of deionized water, ultrasonically dispersed, and then added to the aniline mixture and stirred for 4 hours to obtain Solution B. 6g of APS was then added to another 20mL of 1mol / L sulfuric acid solution, stirred, and then added dropwise to Solution B. A pulsed magnetic field coil was then installed outside the beaker, with the frequency adjusted to 50Hz and the induction power set to 2.2kW, with the magnetic field direction parallel to the bottom of the beaker. The solution was stirred in an ice bath for 12 hours and then allowed to stand. Finally, the solution was vacuum filtered, washed five times with deionized water and five times with ethanol, and dried at 80°C in a vacuum oven for 24 hours to obtain the polyaniline / boron nitride composite nanomaterial (PANI-CFBN).

[0055] Prepare 20 mL of a mixed solution of anhydrous ethanol and deionized water in a volume ratio of 1:1, and adjust the pH to 9 with concentrated ammonia water; weigh 4 g of TiO2 and pour it into a beaker, ultrasonically disperse it for 10 minutes, and stir it at 80°C for 20 minutes; mix 0.2 g of KH-570 with 20 mL of ethanol and add it to the beaker, stir it for 1.5 hours, age it at room temperature for 20 minutes, and filter and dry it to obtain modified TiO2 particles.

[0056] Ultrasonic dispersion of 1g of PANI-CFBN in 7ml of DMF solution was performed. 1g of polyvinylidene fluoride (PVDF) powder was then added, stirred, and allowed to stand until the resulting composite colloid was free of bubbles, resulting in a uniform PANI-CFBN casting solution. The casting solution was then spin-coated onto a metal surface using a spin coater at 800rpm for 5 seconds, using a 1.5ml casting solution. The coating was then dried at 120°C for 24 hours to produce an integrated coating with radar-absorbing and corrosion-resistant properties.

[0057] Example 2 Preparation of PVDF-based PANI-CFBN@TiO2 coating

[0058] First, urea (1.2 g) and boric acid (0.61 g) were dissolved in 200 ml of ultrapure water, stored at 100°C for 2 hours, cooled to room temperature, and filtered to dryness to obtain a urea borate precursor (M·2B). This was then dispersed in water, 1 g of phosphoric acid was added, stirred at room temperature for 12 hours, and filtered to dryness to obtain a white M·2B·P precursor. The M·2B·P precursor was placed in a horizontal tube furnace, purged with nitrogen, and heated to 1100°C at a rate of 5°C / min. The temperature was maintained for 6 hours to obtain loose, porous BNNS.

[0059] 0.24 g of porous BNNS was dispersed in 80 mL of water. Simultaneously, 0.29 g of Co(NO₃)₂·6H₂O and 0.28 g of FeSO₄·7H₂O were dispersed in 40 mL of a mixture of water and ethylene glycol (EG) (water:ethylene glycol = 1:3) and stirred to obtain Solution A. The porous BNNS solution was added to Solution A and stirred to obtain a uniform mixture. Afterward, 6 mL of ammonia was added and stirred for 2 hours. The mixture was then reacted at 200°C under high pressure for 24 hours. After the reaction was complete, the high-pressure steam was cooled to room temperature. The resulting precipitate was filtered, washed five times with deionized water and ethanol, and dried at 60°C to obtain CoFe₂O₄-BNNS.

[0060] 6g of aniline was added to 500mL of 1.5mol / L sulfuric acid solution and stirred. 0.5g of CoFe2O4-BNNS was added to 100mL of deionized water, ultrasonically dispersed, and then added to the aniline mixture and stirred for 4 hours to obtain Solution B. 4.5g of APS was then added to 20mL of 1mol / L hydrochloric acid solution, stirred, and then added dropwise to Solution B. The mixture was stirred in an ice bath for 12 hours and allowed to stand. Finally, the solution was vacuum filtered, washed five times with deionized water and five times with ethanol, and dried under vacuum at 80°C for 24 hours to obtain the polyaniline / boron nitride composite nanomaterial (PANI-CFBN).

[0061] Prepare 20 mL of a mixed solution of anhydrous ethanol and deionized water in a volume ratio of 1:1, and adjust the pH to 9 with concentrated ammonia water; weigh 4 g of TiO2 and pour it into a beaker, ultrasonically disperse it for 10 minutes, and stir it at 80°C for 20 minutes; mix 0.1 g of KH-570 with 10 mL of ethanol and add it to the beaker, stir it for 1.5 hours, age it at room temperature for 30 minutes, and filter and dry it to obtain modified TiO2 particles.

[0062] 2g of PANI-CFBN and 0.5g of TiO2 were ultrasonically dispersed in 7ml of DMF solution. 2g of polyvinylidene fluoride (PVDF) powder was then added, stirred evenly, and allowed to stand until the resulting composite colloid was free of bubbles, resulting in a uniform PANI-CFBN casting solution. The casting solution was then spin-coated onto a metal surface using a spin coater at 800 rpm for 5 seconds, with a total volume of 1.5ml. The coating was then dried to produce an integrated microwave-absorbing and corrosion-resistant coating.

[0063] Example 3 Preparation of PVDF-based PANI-CFBN@TiO2 coating

[0064] First, urea (0.6 g) and boric acid (1.24 g) were dissolved in 200 ml of ultrapure water, stored at 80°C for 2 hours, cooled naturally to room temperature, and filtered and dried to obtain a urea borate precursor (M·2B). This was then dispersed in water, 1 g of phosphoric acid was added, stirred at room temperature for 12 hours, and filtered and dried to obtain a white M·2B·P precursor. The M·2B·P precursor was placed in a horizontal tube furnace, purged with nitrogen, and heated to 1100°C at a rate of 5°C / min. The temperature was maintained for 4 hours to obtain loose, porous BNNS.

[0065] 0.48 g of porous BNNS was dispersed in 80 mL of water. Simultaneously, 0.29 g of Co(NO₃)₂·6H₂O and 0.28 g of FeSO₄·7H₂O were dispersed in 80 mL of a mixture of water and ethylene glycol (EG) (water:ethylene glycol = 1:3) and stirred to obtain Solution A. The porous BNNS solution was added to Solution A and stirred thoroughly. Afterward, 4 mL of ammonia was added and stirred for 2 hours. The mixture was then reacted at 180°C under high pressure for 24 hours. After the reaction was complete, the high-pressure steam was cooled to room temperature. The resulting precipitate was filtered, washed five times with deionized water and ethanol, and dried at 90°C to obtain CoFe₂O₄-BNNS.

[0066] 3g of aniline was added to 500mL of 1.5mol / L sulfuric acid solution and stirred. 0.5g of CoFe2O4-BNNS was added to 100mL of deionized water, ultrasonically dispersed, and then added to the aniline mixture and stirred for 6 hours to obtain Solution B. 4.5g of APS was then added to another 20mL of 1mol / L sulfuric acid solution, stirred, and then added dropwise to Solution B. A pulsed magnetic field coil was then installed outside the beaker, adjusted to a frequency of 50Hz and an induction power of 12kW, with the magnetic field direction parallel to the bottom of the beaker. The solution was stirred in an ice bath for 12 hours and allowed to stand. Finally, the solution was vacuum filtered, washed five times with deionized water and five times with ethanol, and dried at 80°C in a vacuum oven for 24 hours to obtain the polyaniline / boron nitride composite nanomaterial (PANI-CFBN).

[0067] Prepare 20 mL of a mixed solution of anhydrous ethanol and deionized water in a volume ratio of 1:1, and adjust the pH to 9 with concentrated ammonia water; weigh 6 g of TiO2 and pour it into a beaker, ultrasonically disperse it for 10 minutes, and stir it at 80°C for 20 minutes; mix 0.1 g of KH-570 with 10 mL of ethanol and add it to the beaker, stir it for 1.5 hours, age it at room temperature for 30 minutes, and filter and dry it to obtain modified TiO2 particles.

[0068] 1g of PANI-CFBN and 0.5g of TiO2 were ultrasonically dispersed in 7ml of DMF solution. 1g of polyvinylidene fluoride (PVDF) powder was then added, stirred evenly, and allowed to stand until no bubbles formed within the resulting composite colloid, resulting in a uniform PANI-CFBN casting solution. The casting solution was then spin-coated onto a metal surface using a spin coater at 800 rpm for 8 seconds, with a 2ml casting solution. The coating was then dried to produce an integrated microwave-absorbing and corrosion-resistant coating.

[0069] Example 4 Preparation of PVDF-based PANI-CFBN@TiO2 coating

[0070] First, urea (0.6 g) and boric acid (1.24 g) were dissolved in 200 ml of ultrapure water, stored at 80°C for 2 hours, cooled naturally to room temperature, and filtered and dried to obtain a urea borate precursor (M·2B). This was then dispersed in water, 1 g of phosphoric acid was added, stirred at room temperature for 12 hours, and filtered and dried to obtain a white M·2B·P precursor. The M·2B·P precursor was placed in a horizontal tube furnace, purged with nitrogen, and heated to 1100°C at a rate of 5°C / min. The temperature was maintained for 4 hours to obtain loose, porous BNNS.

[0071] 0.24 g of porous BNNS was dispersed in 40 mL of water. Simultaneously, 0.29 g of Co(NO₃)₂·6H₂O and 0.28 g of FeSO₄·7H₂O were dispersed in 80 mL of a mixture of water and ethylene glycol (EG) (water:ethylene glycol = 1:3) and stirred to obtain Solution A. The porous BNNS solution was added to Solution A and stirred to obtain a uniform mixture. Afterward, 4 mL of ammonia was added and stirred for 2 hours. The mixture was then reacted at 180°C under high pressure for 24 hours. After the reaction was complete, the high-pressure steam was cooled to room temperature. The resulting precipitate was filtered, washed five times with deionized water and ethanol, and dried at 60°C to obtain CoFe₂O₄-BNNS.

[0072] 3g of aniline was added to 500mL of 1.5mol / L sulfuric acid solution and stirred. 0.5g of CoFe2O4-BNNS was added to 100mL of deionized water, ultrasonically dispersed, and then added to the aniline mixture and stirred for 6 hours to obtain Solution B. 4.5g of APS was then added to another 20mL of 1mol / L sulfuric acid solution, stirred, and then added dropwise to Solution B. A pulsed magnetic field coil was then installed outside the beaker, adjusted to a frequency of 50Hz and an induction power of 12kW, with the magnetic field direction parallel to the bottom of the beaker. The solution was stirred in an ice bath for 12 hours and allowed to stand. Finally, the solution was vacuum filtered, washed five times with deionized water and five times with ethanol, and dried at 80°C in a vacuum oven for 24 hours to obtain the polyaniline / boron nitride composite nanomaterial (PANI-CFBN).

[0073] Prepare 20 mL of a mixed solution of anhydrous ethanol and deionized water in a volume ratio of 1:1, and adjust the pH to 9 with concentrated ammonia water; weigh 4 g of TiO2 and pour it into a beaker, ultrasonically disperse it for 10 minutes, and stir it at 80°C for 20 minutes; mix 0.1 g of KH-570 with 10 mL of ethanol and add it to the beaker, stir it for 1.5 hours, age it at room temperature for 20 minutes, and filter and dry it to obtain modified TiO2 particles.

[0074] 2g of PANI-CFBN and 0.5g of TiO2 were ultrasonically dispersed in 7ml of DMF solution. 2g of polyvinylidene fluoride (PVDF) powder was then added, stirred evenly, and allowed to stand until no bubbles formed within the resulting composite colloid, resulting in a uniform PANI-CFBN casting solution. The casting solution was then spin-coated onto a metal surface using a spin coater at 800 rpm for 5 seconds, with a total volume of 2ml. The coating was then dried to produce an integrated microwave-absorbing and corrosion-resistant coating.

[0075] Comparative Example 1

[0076] The only difference from Example 4 is that TiO2 nanoparticles are not added in step 4.

[0077] Comparative Example 2

[0078] The only difference from Example 4 is that no magnetic field is introduced in step 3.

[0079] Comparative Example 3

[0080] The only difference from Example 4 is that the mass ratio of PANI-CFBN to TiO2 is changed.

[0081] Table 1 is a comparison of the wave absorption and super-hydrophobic properties of the coatings with lotus leaf-like micromorphology in Example 4, the coatings of Comparative Example 1, Comparative Example 2, and Comparative Example 3. As can be seen from Table 1, the coating has the best overall performance in Example 4. The coating of Comparative Example 1 does not add TiO2 nanoparticles, which seriously affects the construction of a micro-nano structure with a lotus leaf shape. Comparative Example 2 does not introduce a magnetic field, and the PANI-CFBN composite material agglomerates, the material structure is disordered, and the electromagnetic wave propagation path becomes shorter, thus significantly affecting the wave absorption performance of the material. Comparative Example 3 changes the PANI-CFBN and TiO2 mass ratio, and the TiO2 nanoparticles agglomerate seriously. In Example 4, the coating with a lotus leaf-like micromorphology introduces a magnetic field to optimize the material structure. The porous BNNS extends the electromagnetic wave propagation path and promotes the absorption and scattering of electromagnetic waves. The directional arrangement of polyaniline and modified porous boron nitride further improves the material's anti-corrosion and wave-absorbing properties. The addition of TiO2 nanoparticles constructs a unique lotus leaf-like microstructure, which significantly improves the material's superhydrophobic properties. Therefore, it has the best overall performance and is superior to all comparative examples.

[0082] Table 1 Comparison of the microwave absorption and anti-corrosion properties of the PVDF-based PANI-CFBN@TiO2 coating in Example 4, the coating in Example 1, the coating in Example 2, and the coating in Example 3

[0083]

[0084]

[0085] Figure 1 This is a schematic diagram of the microscopic morphology of the PVDF-based PANI-CFBN@TiO2 coating prepared by the present invention. Figure 1 It can be seen that TiO2 nanoparticles are uniformly attached to the surface of PANI-CFBN.

[0086] Although specific embodiments of the present invention have been described above, those skilled in the art will appreciate that these are merely illustrative and that the scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, and such changes and modifications are intended to fall within the scope of the present invention.

Claims

1. A metal surface coating with integrated microwave absorption and corrosion protection functions, comprising: A lotus-shaped PANI-CFBN@TiO2 casting solution is constructed by aligning a PANI-CFBN composite material and modified TiO2 nanoparticles. The casting solution is attached to a metal surface by spin coating. The preparation method comprises the following steps: Step 1: Preparation of porous BNNS Boric acid and urea were dissolved in ultrapure water, heated and stirred, filtered and dried, and then dispersed in water. Phosphoric acid was added, stirred evenly, dried, and calcined in a horizontal tube furnace to obtain porous BNNS. Step 2: Magnetic modification of porous BNNS The porous BNNS prepared in step 1 was dispersed in deionized water, and Co(NO3)2·6H2O and FeSO4·7H2O were dispersed in a mixture of water and ethylene glycol. The mixture was evenly mixed with the porous BNNS aqueous solution and ammonia was added to react. After drying, CoFe2O4-BNNS was obtained. Step 3: Oriented alignment of PANI-CFBN composites The CoFe2O4-BNNS obtained in step 2 was dispersed in deionized water, aniline and acidic solution were added, and ammonium sulfate was added after stirring evenly. A pulsed magnetic field coil was installed on the outside of the beaker, and the mixture was stirred in an ice bath. The mixture was vacuum filtered, washed, and dried to obtain a polyaniline / boron nitride composite nanomaterial; Step 4: Preparation of modified TiO2 nanoparticles TiO2 is added to a mixed solution of anhydrous ethanol and deionized water, and concentrated ammonia is used to adjust the pH; a coupling agent is mixed with ethanol and then added with stirring, aged at room temperature, filtered and dried to obtain modified TiO2 nanoparticles; Step 5: Constructing lotus-shaped PANI-CFBN@TiO2 The nanofillers prepared in steps 3 and 4 were dispersed in an organic solution, polyvinylidene fluoride powder was added, and the mixture was stirred and ultrasonicated alternately. After standing, a uniform lotus leaf-shaped PANI-CFBN@TiO2 casting solution was obtained; Step 6: Preparation of PVDF-based PANI-CFBN@TiO2 coating Spin-coat the casting solution obtained in step 5 on the metal surface using a spin coater to form a coating, and dry it to obtain an integrated coating with microwave absorbing and anti-corrosion functions; The mass ratio of PANI-CFBN, TiO2, and PVDF is 2:1:2-4:1:

4.

2. A method for preparing a metal surface coating with integrated microwave absorption and anti-corrosion functions, characterized in that: The preparation method consists of the following steps: Step 1: Preparation of porous BNNS Boric acid and urea were dissolved in ultrapure water, heated and stirred, filtered and dried, and then dispersed in water. Phosphoric acid was added, stirred evenly, dried, and calcined in a horizontal tube furnace to obtain porous BNNS. Step 2: Magnetic modification of porous BNNS The porous BNNS prepared in step 1 was dispersed in deionized water, and Co(NO3)2·6H2O and FeSO4·7H2O were dispersed in a mixture of water and ethylene glycol. The mixture was evenly mixed with the porous BNNS aqueous solution and ammonia was added to react. After drying, CoFe2O4-BNNS was obtained. Step 3: Oriented alignment of PANI-CFBN composites The CoFe2O4-BNNS obtained in step 2 was dispersed in deionized water, aniline and acidic solution were added, and ammonium sulfate was added after stirring evenly. A pulsed magnetic field coil was installed on the outside of the beaker, and the mixture was stirred in an ice bath. The mixture was vacuum filtered, washed, and dried to obtain a polyaniline / boron nitride composite nanomaterial; Step 4: Preparation of modified TiO2 nanoparticles TiO2 is added to a mixed solution of anhydrous ethanol and deionized water, and concentrated ammonia is used to adjust the pH; a coupling agent is mixed with ethanol and then added with stirring, aged at room temperature, filtered and dried to obtain modified TiO2 nanoparticles; Step 5: Constructing lotus-shaped PANI-CFBN@TiO2 The nanofillers prepared in steps 3 and 4 were dispersed in an organic solution, polyvinylidene fluoride powder was added, and the mixture was stirred and ultrasonicated alternately. After standing, a uniform lotus leaf-shaped PANI-CFBN@TiO2 casting solution was obtained; Step 6: Preparation of PVDF-based PANI-CFBN@TiO2 coating Spin-coat the casting solution obtained in step 5 on the metal surface using a spin coater to form a coating, and dry it to obtain an integrated coating with microwave absorbing and anti-corrosion functions; The mass ratio of PANI-CFBN, TiO2, and PVDF is 2:1:2-4:1:

4.

3. The preparation method according to claim 2, characterized in that In the step 1, the molar ratio of uric acid to boric acid is 1:2-2:1, and the molar ratio of urea borate precursor to phosphoric acid is 1:

1.

4. The preparation method according to claim 2, characterized in that The horizontal tube furnace calcination in the step 1 is heated to 1100° C. at a rate of 5° C. / min, and the heating time is 4-6 hours.

5. The preparation method according to claim 2, characterized in that In the second step, the amount of the porous BNNS material is 0.01-0.02 mol, deionized water is 40-80 mL, the molar ratio of Co(NO3)2·6H2O and FeSO4·7H2O is 1:2, and the volume ratio of the mixture of water and ethylene glycol is 1:

3.

6. The preparation method according to claim 2, characterized in that In step 3, the concentration of aniline in the acidic solution is 0.006 g / mL~0.012 g / mL, the concentration of CFBN in deionized water is 0.005 g / mL~0.01 g / mL, the volume ratio of deionized water to the acidic solution is 1:5, the concentration of APS in the acidic solution is 0.225 g / mL~0.3 g / mL, and the mass ratio of APS to CFBN is 6:1~9:

1.

7. The preparation method according to claim 2, characterized in that In step 3, the frequency of the pulse magnetic field coil is adjusted to 50 Hz, the induction power is 2.2 kW to 12 kW, and the direction of the magnetic field is parallel to the bottom of the beaker.

8. The preparation method according to claim 2, characterized in that In step 4, the volume ratio of anhydrous ethanol and deionized water is 1:1, the pH is adjusted to 9, the mass ratio of TiO2 to coupling agent is 30:1~40:1, and the concentration of TiO2 in the mixed solution of anhydrous ethanol and deionized water is 0.2g / mL~0.3g / mL.

9. The preparation method according to claim 2, characterized in that The organic solution in step five is N-dimethylformamide, and the concentration of PANI-CFBN in DMF is 0.15 g / mL to 0.3 g / mL.

10. The preparation method according to claim 2, characterized in that In step 6, the spin coater speed is set to 800-1000 rpm, lasting for 5-8 s, and the casting solution is 1.5-2.0 mL.

Images