Corrosion-resistant nano ceramic coating for aircraft and preparation method thereof

Abstract

The application discloses an aircraft corrosion-resistant nanometer ceramic coating and a preparation method thereof, relates to the technical field of coating, and belongs to the patent classification C09D1 / 00. The method comprises the following steps: firstly, hydroxylation and silane coupling agent surface modification are carried out on zirconia-alumina composite nanometer ceramic powder; then, free radical copolymerization grafting of trifluoroethyl acrylate monomers is carried out to form modified nanometer ceramic powder coated with fluoropolymer resin. Meanwhile, a three-dimensional interpenetrating network structure matrix resin is prepared by copolymerization and isocyanate crosslinking of allyl modified bisphenol A epoxy resin and acrylic polysiloxane resin. Finally, the modified nanometer ceramic powder is compounded with the crosslinking modified matrix resin and additives, and the final coating is obtained through dispersion and defoaming. The inorganic ceramic core-organic fluororesin coating layer structure and the high crosslinking density resin matrix are synergistically combined, the corrosion resistance of the coating in harsh environments such as acid, alkali, salt mist and aviation fuel is significantly improved, and the coating is especially suitable for the protection of the surface of an aircraft.

Description

Technical Field

[0001] This invention relates to the field of coating technology, belonging to patent classification number C09D1 / 00, specifically to a corrosion-resistant nano-ceramic coating for aircraft and its preparation method. Background Technology

[0002] In the aerospace field, aircraft face complex and harsh service environments throughout their entire life cycle, including high salinity and humidity in the ocean, low temperature and pressure at high altitudes, acid and alkali corrosion, and airflow erosion. As the first line of defense for the aircraft's airframe and critical components, the corrosion resistance of the coating directly determines the aircraft's structural safety, stealth stability, and service life. With the continuous development of aviation technology, aircraft speed, endurance, and combat radius are constantly increasing, leading to increasingly stringent requirements for coating protection. Coatings must not only resist corrosion failure caused by salt spray, humidity, and chemical media, but also achieve comprehensive performance characteristics such as lightweight design, high temperature resistance, and peel resistance.

[0003] However, existing aircraft coatings generally suffer from insufficient corrosion resistance. Traditional aircraft coatings often employ organic film-forming systems such as epoxy resins and polyurethanes, or composite systems with added functional fillers like ferrites. These coatings are prone to oxidation, cracking, and peeling in extreme environments. For example, iron-based stealth coatings commonly used on carrier-based aircraft, in the high-salt and high-humidity marine environment, surface scratches or damage can expose internal iron elements and cause rapid oxidation, forming large areas of rust. This not only weakens stealth performance and increases flight drag, but may also cause failures in critical components such as engines due to rust flakes. Even if some coatings improve short-term corrosion resistance through optimized formulations, it is difficult to balance stability and overall performance during long-term service. For instance, some thermal barrier coatings have high porosity and insufficient density, failing to effectively block the penetration of corrosive media and leading to premature failure of the substrate material. On the other hand, some high-performance coatings rely on complex preparation processes (such as electron beam physical vapor deposition), resulting in high costs and difficulties in large-scale application.

[0004] Poor corrosion resistance of coatings has become a key factor restricting the improvement of aircraft reliability and the reduction of maintenance costs. Data shows that maintenance costs due to coating corrosion in the aviation industry reach billions of dollars annually. Furthermore, corrosion-induced problems such as coating peeling and reduced structural strength seriously threaten flight safety and shorten aircraft service life. Although existing technologies have attempted to introduce nano-ceramic materials into aerospace coatings to improve performance, challenges remain in the preparation process, including uneven dispersion, insufficient bonding strength, and complex processes. This has prevented the development of mature aircraft coating products that balance excellent corrosion resistance with practical application requirements. Therefore, developing a nano-ceramic coating for aircraft with excellent corrosion resistance and balanced overall performance has significant practical importance and application value. Summary of the Invention

[0005] The purpose of this invention is to provide a corrosion-resistant nano-ceramic coating for aircraft and its preparation method, so as to solve the technical problem of poor corrosion resistance of aircraft coatings mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing a corrosion-resistant nano-ceramic coating for aircraft includes the following steps:

[0008] S1. Zirconia-alumina composite nano-ceramic powder is added to deionized water, ultrasonically dispersed, then dilute nitric acid and hydrogen peroxide are added, the mixture is stirred and reacted, and after washing and drying, hydroxylated composite nano-ceramic powder is obtained.

[0009] S2. The hydroxylated composite nano-ceramic powder was added to anhydrous ethanol, ultrasonically dispersed, pH adjusted, silane coupling agent KH-560 was added, the mixture was stirred and reacted, and after centrifugation, washing and drying, the coupling agent modified ceramic powder was obtained.

[0010] S3. Add the coupling agent-modified ceramic powder to N,N-dimethylformamide, disperse it by ultrasonication, add trifluoroethyl acrylate, allyl glycidyl ether and benzoyl peroxide, introduce nitrogen gas, heat and stir to react, then cool down, add diethylenetriamine, continue stirring to react, and after centrifugation, washing and drying, obtain fluoropolymer resin-modified nano-ceramic powder.

[0011] S4. Add allyl-modified bisphenol A epoxy resin to a mixed solvent of N,N-dimethylformamide and ethyl acetate, stir to dissolve, then add dispersant, leveling agent and defoamer, stir evenly to obtain epoxy resin base material;

[0012] S5. Mix epoxy resin base material with acrylic polysiloxane resin, add benzoyl peroxide, introduce nitrogen gas, stir and react, then add isocyanate trimer curing agent and catalyst, stir and react to obtain crosslinked modified matrix resin.

[0013] S6. The cross-linked modified matrix resin, fluoropolymer resin modified nano-ceramic powder, and antioxidant are mixed, ultrasonically dispersed, then high-speed dispersed, then degassed under reduced pressure, thickener is added to adjust the viscosity, and then filtered to obtain a corrosion-resistant nano-ceramic coating for aircraft.

[0014] In the technical solution of this invention, the corrosion resistance of aircraft coatings is improved synergistically from the following two aspects: Firstly, the zirconia-alumina composite nano-ceramic powder, as an inorganic corrosion-resistant core, has extremely strong chemical inertness and can resist the erosion of corrosive media such as acids, alkalis, salt spray, and aviation fuel. After modification with fluorinated polymer resin, it forms a composite structure of inorganic ceramic corrosion-resistant core and organic fluorine resin coating layer, which further enhances the shielding ability against corrosive media and prevents the media from penetrating to the substrate surface. At the same time, the nano-sized particles allow it to be uniformly dispersed in the coating, which can fill the micropores in the cross-linked matrix resin, greatly improve the density of the coating, reduce the penetration channels of corrosive media, and form a synergistic barrier with the resin network protective layer. Meanwhile, in terms of mechanical property enhancement, ceramic powder itself has high hardness and excellent wear resistance. After being uniformly dispersed in the matrix, it can significantly improve the hardness, wear resistance and impact resistance of the coating, prevent the coating from being damaged by vibration, friction or slight impact during aircraft service, and maintain the structural integrity of the corrosion-resistant system. Its high thermal stability can also enhance the high and low temperature resistance of the coating, prevent the coating from cracking due to temperature cycling, and indirectly ensure long-term corrosion resistance. On the other hand, the abundant siloxane groups in the acrylic polysiloxane resin molecular chain endow the matrix with outstanding weather resistance and UV aging resistance, which can prevent the coating from degrading and chalking under strong ultraviolet radiation at high altitudes of aircraft, maintain the long-term structural integrity of the coating, and prevent the coating from providing a penetration channel for corrosive media due to aging and damage. In addition, the resin and allyl modified epoxy resin form a dense three-dimensional interpenetrating network structure through free radical copolymerization and isocyanate crosslinking reaction, which greatly increases the crosslinking density of the matrix and reduces the micropores and penetration channels in the system, thus structurally blocking the migration of corrosive media. At the same time, the crosslinked matrix has both high mechanical strength and excellent high and low temperature stability, which can resist the coating cracking caused by environmental stress such as temperature cycling and vibration during aircraft service, and prevent corrosive media from penetrating to the substrate surface through cracks, thereby further improving the corrosion resistance of the coating.

[0015] Preferably, in step S2, the mass ratio of hydroxylated composite nano-ceramic powder to silane coupling agent KH-560 is 10:(0.8~1.5).

[0016] Preferably, in step S3, the mass ratio of trifluoroethyl acrylate to allyl glycidyl ether is 35:(2-5).

[0017] Preferably, in step S3, N,N-dimethylformamide also contains hydroxyethyl acrylate.

[0018] In the technical solution of this invention, the research and development team discovered through in-depth research that the fluoropolymer resin on the surface of the modified nano-ceramic powder has a low-polarity hydrophobic structure, which has an interfacial polarity difference with the high-polarity polysiloxane-epoxy crosslinked matrix. This results in insufficient spreading of the matrix resin on the surface of the ceramic powder, forming local low crosslinking density areas around the ceramic powder. At the same time, there is a difference in shrinkage rate between the fluoropolymer coating layer and the matrix resin, which causes micro-cracks to be generated in the coating during the curing process, forming penetration channels for corrosive media such as salt spray and aviation fuel, thereby affecting the synergistic anti-corrosion performance of both aspects. To further address this technical problem, this invention adds hydroxyethyl acrylate to N,N-dimethylformamide. The molecule contains unsaturated double bonds and hydroxyl groups. The double bonds can participate in free radical copolymerization with TFEA and allyl glycidyl ether, grafting polar hydroxyl groups onto the surface of the fluororesin coating. The hydroxyl groups can form hydrogen bonds with the silanol and epoxy groups in the matrix resin, effectively reducing the polarity difference between the fluororesin and the matrix. Simultaneously, the hydroxyl groups can act as crosslinking active sites, participating in subsequent crosslinking reactions of the matrix. This solves the problems of insufficient matrix resin spreading, localized low crosslinking density, and micro-cracks during curing, thereby further improving the corrosion resistance of the coating.

[0019] Preferably, the mass ratio of trifluoroethyl acrylate to hydroxyethyl acrylate is 35:(3-6).

[0020] Preferably, in step S5, the mass ratio of allyl modified bisphenol A epoxy resin to acrylic polysiloxane resin is 85:(30-38).

[0021] Preferably, in step S6, the mass ratio of the crosslinked modified matrix resin to the fluoropolymerized resin modified nano-ceramic powder is 7:(1-2).

[0022] A corrosion-resistant nano-ceramic coating for aircraft is prepared by the method described above.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. By modifying zirconium oxide-alumina composite nano-ceramic powder with fluorinated polymer resin to form an inorganic ceramic core-organic fluorine resin coating structure, the penetration of corrosive media such as acids, alkalis, salt spray and aviation fuel is effectively shielded; at the same time, nanoparticles fill the pores of the coating, enhance the density, and work together with the cross-linked resin network to form a dual protective barrier.

[0025] 2. The high hardness and wear resistance of nano-ceramic powder improve the impact resistance, wear resistance and hardness of the coating, reducing damage caused by aircraft vibration, friction or impact; its high thermal stability also improves the high and low temperature resistance of the coating, prevents cracking caused by temperature cycling and maintains the integrity of the corrosion-resistant system.

[0026] 3. By adding hydroxyethyl acrylate, the polarity difference between the fluoropolymer and the matrix resin is reduced, promoting interfacial bonding and cross-linking reaction, reducing micro-cracks during the curing process, thereby avoiding the formation of channels for corrosive media penetration and further improving the overall corrosion resistance. Attached Figure Description

[0027] Figure 1 The image shows the surface of the coating prepared in Example 1 of the invention after coating. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] The zirconia-alumina composite nano-ceramic powder used in the specific embodiments is model SZ-ZMA, manufactured by Jiangxi Saici Materials Co., Ltd. The allyl-modified bisphenol A epoxy resin, model E-51-AM, with an allyl content of 5wt%, is manufactured by Huibo New Materials Technology Co., Ltd. The acrylic polysiloxane resin, model SH-3010A, is manufactured by Quark New Materials Co., Ltd.

[0030] Example 1

[0031] A method for preparing a corrosion-resistant nano-ceramic coating for aircraft includes the following steps:

[0032] Step 1: Weigh 22g of zirconia-alumina composite nano-ceramic powder (particle size 30nm) and add it to 200mL of deionized water. Disperse the powder ultrasonically at 40kHz frequency and 300W power for 35min. Transfer the powder to a 500mL three-necked flask and heat it to 80℃. Slowly add a mixed etching solution of 12g of 12% dilute nitric acid and 8g of 30% hydrogen peroxide. Stir the mixture at 250r / min for 2.5h. After the reaction, filter and wash the powder with deionized water until the pH of the filtrate is 7.0. Place the solid in a vacuum drying oven at 125℃ and dry it for 12h to obtain hydroxylated composite nano-ceramic powder.

[0033] Step 2: Weigh 20g of hydroxylated composite nano-ceramic powder and add it to 55g of anhydrous ethanol. Disperse the mixture ultrasonically at 40kHz frequency and 300W power for 20min. Adjust the pH of the system to 4.2 with glacial acetic acid. Add 2.5g of silane coupling agent KH-560 and place it in a 62℃ constant temperature water bath. Stir at 200r / min for 3.5h. After the reaction, centrifuge at 10000r / min for 15min, wash three times with anhydrous ethanol, and vacuum dry at 100℃ for 8h to obtain coupling agent modified ceramic powder.

[0034] Step 3: Weigh 23g of coupling agent modified ceramic powder and add it to 100g of N,N-dimethylformamide (DMF). Disperse the powder ultrasonically at 50kHz frequency and 400W power for 40min. Add 35g of trifluoroethyl acrylate (TFEA), 4g of allyl glycidyl ether and 5g of hydroxyethyl acrylate. Heat the mixture to 85℃ and add 0.5g of benzoyl peroxide (BPO). Purge the mixture with nitrogen three times to replace the air. Stir the mixture at 300r / min for 4h. Then cool the mixture to 60℃ and add 0.4g of diethylenetriamine. Continue stirring for 3h. Centrifuge at 10000r / min for 20min. Wash the mixture twice with DMF, once with ethanol, and once with ethyl acetate. Dry the mixture under vacuum at 115℃ for 10h to obtain fluoropolymer resin modified nano-ceramic powder.

[0035] Step 4: Weigh 85g of allyl-modified bisphenol A epoxy resin (E-51-AM) and add it to 120g of a mixed solvent of DMF and ethyl acetate (mass ratio 1:1). Place the mixture in a 75℃ constant temperature water bath and stir at 300r / min for 90min to dissolve it. Add 4g of dispersant BYK-163, 2.5g of leveling agent BYK-333 and 1g of defoamer BYK-066, and continue stirring for 20min to obtain a uniform epoxy resin base.

[0036] Step 5: Cool the above epoxy resin base to 62℃, add 36g of acrylic polysiloxane resin, stir evenly, add 0.5g of BPO initiator, purge the air with nitrogen three times, heat to 87℃ and stir at 300r / min for 3.5h, then cool to 80℃, add 105g of isocyanate trimer curing agent (Desmodur N3390) and 0.2g of catalyst dibutyltin dilaurate (DBTDL), keep warm and react for 2.5h to obtain crosslinked modified matrix resin.

[0037] Step 6: Cool 280g of crosslinked modified matrix resin to 60℃, add 70g of fluoropolymer resin modified nano-ceramic powder and 2g of antioxidant 1010, ultrasonically disperse at 40kHz frequency and 300W power for 30min, then disperse at 12000r / min for 20min, and then transfer to a rotary evaporator for degassing under reduced pressure at 65℃ and -0.09MPa for 30min. Add 3g of polyamide wax thickener (BYK-410) to adjust the viscosity to... (25℃) After filtration through a 500-mesh filter, a corrosion-resistant nano-ceramic coating for aircraft is obtained.

[0038] Example 2

[0039] A method for preparing a corrosion-resistant nano-ceramic coating for aircraft includes the following steps:

[0040] Step 1: Weigh 22g of zirconia-alumina composite nano-ceramic powder (particle size 30nm) and add it to 200mL of deionized water. Disperse the powder ultrasonically at 40kHz frequency and 300W power for 35min. Transfer the powder to a 500mL three-necked flask and heat it to 80℃. Slowly add a mixed etching solution of 12g of 12% dilute nitric acid and 8g of 30% hydrogen peroxide. Stir the mixture at 250r / min for 2.5h. After the reaction, filter and wash the powder with deionized water until the pH of the filtrate is 7.0. Place the solid in a vacuum drying oven at 125℃ and dry it for 12h to obtain hydroxylated composite nano-ceramic powder.

[0041] Step 2: Weigh 20g of hydroxylated composite nano-ceramic powder and add it to 55g of anhydrous ethanol. Disperse the mixture ultrasonically at 40kHz frequency and 300W power for 20min. Adjust the pH of the system to 4.2 with glacial acetic acid. Add 1.8g of silane coupling agent KH-560 and place it in a 62℃ constant temperature water bath. Stir at 200r / min for 3.5h. After the reaction, centrifuge at 10000r / min for 15min, wash three times with anhydrous ethanol, and vacuum dry at 100℃ for 8h to obtain coupling agent modified ceramic powder.

[0042] Step 3: Weigh 23g of coupling agent modified ceramic powder and add it to 100g of N,N-dimethylformamide (DMF). Disperse the powder ultrasonically at 50kHz frequency and 400W power for 40min. Add 35g of trifluoroethyl acrylate (TFEA), 3g of allyl glycidyl ether and 4g of hydroxyethyl acrylate. Heat to 85℃ and add 0.5g of benzoyl peroxide (BPO). Purge the air with nitrogen three times and stir at 300r / min for 4h. Then cool to 60℃ and add 0.4g of diethylenetriamine. Continue stirring for 3h. Centrifuge at 10000r / min for 20min. Wash twice with DMF, once with ethanol and once with ethyl acetate. Dry under vacuum at 115℃ for 10h to obtain fluoropolymer resin modified nano-ceramic powder.

[0043] Step 4: Weigh 85g of allyl-modified bisphenol A epoxy resin (E-51-AM) and add it to 120g of a mixed solvent of DMF and ethyl acetate (mass ratio 1:1). Place the mixture in a 75℃ constant temperature water bath and stir at 300r / min for 90min to dissolve it. Add 4g of dispersant BYK-163, 2.5g of leveling agent BYK-333 and 1g of defoamer BYK-066, and continue stirring for 20min to obtain a uniform epoxy resin base.

[0044] Step 5: Cool the above epoxy resin base to 62℃, add 32g of acrylic polysiloxane resin, stir evenly, add 0.5g of BPO initiator, purge the air with nitrogen three times, heat to 87℃ and stir at 300r / min for 3.5h, then cool to 80℃, add 105g of isocyanate trimer curing agent (Desmodur N3390) and 0.2g of catalyst dibutyltin dilaurate (DBTDL), keep warm and react for 2.5h to obtain crosslinked modified matrix resin.

[0045] Step 6: Cool 280g of crosslinked modified matrix resin to 60℃, add 50g of fluoropolymer resin modified nano-ceramic powder and 2g of antioxidant 1010, ultrasonically disperse at 40kHz frequency and 300W power for 30min, then disperse at 12000r / min for 20min, and then transfer to a rotary evaporator for degassing under reduced pressure at 65℃ and -0.09MPa for 30min. Add 3g of polyamide wax thickener (BYK-410) to adjust the viscosity to... (25℃) After filtration through a 500-mesh filter, a corrosion-resistant nano-ceramic coating for aircraft is obtained.

[0046] Example 3

[0047] A method for preparing a corrosion-resistant nano-ceramic coating for aircraft includes the following steps:

[0048] Step 1: Weigh 22g of zirconia-alumina composite nano-ceramic powder (particle size 30nm) and add it to 200mL of deionized water. Disperse the powder ultrasonically at 40kHz frequency and 300W power for 35min. Transfer the powder to a 500mL three-necked flask and heat it to 80℃. Slowly add a mixed etching solution of 12g of 12% dilute nitric acid and 8g of 30% hydrogen peroxide. Stir the mixture at 250r / min for 2.5h. After the reaction, filter and wash the powder with deionized water until the pH of the filtrate is 7.0. Place the solid in a vacuum drying oven at 125℃ and dry it for 12h to obtain hydroxylated composite nano-ceramic powder.

[0049] Step 2: Weigh 20g of hydroxylated composite nano-ceramic powder and add it to 55g of anhydrous ethanol. Disperse the powder ultrasonically at 40kHz frequency and 300W power for 20min. Adjust the pH of the system to 4.2 with glacial acetic acid. Add 2.0g of silane coupling agent KH-560 and place it in a 62℃ constant temperature water bath. Stir at 200r / min for 3.5h. After the reaction, centrifuge at 10000r / min for 15min, wash three times with anhydrous ethanol, and vacuum dry at 100℃ for 8h to obtain coupling agent modified ceramic powder.

[0050] Step 3: Weigh 23g of coupling agent modified ceramic powder and add it to 100g of N,N-dimethylformamide (DMF). Disperse the powder ultrasonically at 50kHz frequency and 400W power for 40min. Add 35g of trifluoroethyl acrylate (TFEA), 3.5g of allyl glycidyl ether and 4.5g of hydroxyethyl acrylate. Heat the mixture to 85℃ and add 0.5g of benzoyl peroxide (BPO). Purge the mixture with nitrogen three times to replace the air. Stir the mixture at 300r / min for 4h. Then cool the mixture to 60℃ and add 0.4g of diethylenetriamine. Continue stirring for 3h. Centrifuge at 10000r / min for 20min. Wash the mixture twice with DMF, once with ethanol, and once with ethyl acetate. Dry the mixture under vacuum at 115℃ for 10h to obtain fluorinated polymer resin modified nano-ceramic powder.

[0051] Step 4: Weigh 85g of allyl-modified bisphenol A epoxy resin (E-51-AM) and add it to 120g of a mixed solvent of DMF and ethyl acetate (mass ratio 1:1). Place the mixture in a 75℃ constant temperature water bath and stir at 300r / min for 90min to dissolve it. Add 4g of dispersant BYK-163, 2.5g of leveling agent BYK-333 and 1g of defoamer BYK-066, and continue stirring for 20min to obtain a uniform epoxy resin base.

[0052] Step 5: Cool the above epoxy resin base to 62℃, add 34g of acrylic polysiloxane resin, stir evenly, add 0.5g of BPO initiator, purge the air with nitrogen three times, heat to 87℃ and stir at 300r / min for 3.5h, then cool to 80℃, add 105g of isocyanate trimer curing agent (Desmodur N3390) and 0.2g of catalyst dibutyltin dilaurate (DBTDL), keep warm and react for 2.5h to obtain crosslinked modified matrix resin.

[0053] Step 6: Cool 280g of crosslinked modified matrix resin to 60℃, add 60g of fluoropolymer resin modified nano-ceramic powder and 2g of antioxidant 1010, ultrasonically disperse at 40kHz frequency and 300W power for 30min, then disperse at 12000r / min for 20min, and then transfer to a rotary evaporator for degassing under reduced pressure at 65℃ and -0.09MPa for 30min. Add 3g of polyamide wax thickener (BYK-410) to adjust the viscosity to... (25℃) After filtration through a 500-mesh filter, a corrosion-resistant nano-ceramic coating for aircraft is obtained.

[0054] Example 4

[0055] A method for preparing a corrosion-resistant nano-ceramic coating for aircraft includes the following steps:

[0056] Step 1: Weigh 22g of zirconia-alumina composite nano-ceramic powder (particle size 30nm) and add it to 200mL of deionized water. Disperse the powder ultrasonically at 40kHz frequency and 300W power for 35min. Transfer the powder to a 500mL three-necked flask and heat it to 80℃. Slowly add a mixed etching solution of 12g of 12% dilute nitric acid and 8g of 30% hydrogen peroxide. Stir the mixture at 250r / min for 2.5h. After the reaction, filter and wash the powder with deionized water until the pH of the filtrate is 7.0. Place the solid in a vacuum drying oven at 125℃ and dry it for 12h to obtain hydroxylated composite nano-ceramic powder.

[0057] Step 2: Weigh 20g of hydroxylated composite nano-ceramic powder and add it to 55g of anhydrous ethanol. Disperse the mixture ultrasonically at 40kHz frequency and 300W power for 20min. Adjust the pH of the system to 4.2 with glacial acetic acid. Add 3.0g of silane coupling agent KH-560 and place it in a 62℃ constant temperature water bath. Stir at 200r / min for 3.5h. After the reaction, centrifuge at 10000r / min for 15min, wash three times with anhydrous ethanol, and vacuum dry at 100℃ for 8h to obtain coupling agent modified ceramic powder.

[0058] Step 3: Weigh 23g of coupling agent modified ceramic powder and add it to 100g of N,N-dimethylformamide (DMF). Disperse the powder ultrasonically at 50kHz frequency and 400W power for 40min. Add 35g of trifluoroethyl acrylate (TFEA), 5g of allyl glycidyl ether and 6g of hydroxyethyl acrylate. Heat to 85℃ and add 0.5g of benzoyl peroxide (BPO). Purge the air with nitrogen three times and stir at 300r / min for 4h. Then cool to 60℃ and add 0.4g of diethylenetriamine. Continue stirring for 3h. Centrifuge at 10000r / min for 20min. Wash twice with DMF, once with ethanol and once with ethyl acetate. Dry under vacuum at 115℃ for 10h to obtain fluoropolymer resin modified nano-ceramic powder.

[0059] Step 4: Weigh 85g of allyl-modified bisphenol A epoxy resin (E-51-AM) and add it to 120g of a mixed solvent of DMF and ethyl acetate (mass ratio 1:1). Place the mixture in a 75℃ constant temperature water bath and stir at 300r / min for 90min to dissolve it. Add 4g of dispersant BYK-163, 2.5g of leveling agent BYK-333 and 1g of defoamer BYK-066, and continue stirring for 20min to obtain a uniform epoxy resin base.

[0060] Step 5: Cool the above epoxy resin base to 62℃, add 38g of acrylic polysiloxane resin, stir evenly, add 0.5g of BPO initiator, purge the air with nitrogen three times, heat to 87℃ and stir at 300r / min for 3.5h, then cool to 80℃, add 105g of isocyanate trimer curing agent (Desmodur N3390) and 0.2g of catalyst dibutyltin dilaurate (DBTDL), keep warm and react for 2.5h to obtain crosslinked modified matrix resin.

[0061] Step 6: Cool 280g of crosslinked modified matrix resin to 60℃, add 80g of fluoropolymer resin modified nano-ceramic powder and 2g of antioxidant 1010, ultrasonically disperse at 40kHz frequency and 300W power for 30min, then disperse at 12000r / min for 20min, and then transfer to a rotary evaporator for degassing under reduced pressure at 65℃ and -0.09MPa for 30min. Add 3g of polyamide wax thickener (BYK-410) to adjust the viscosity to... (25℃) After filtration through a 500-mesh filter, a corrosion-resistant nano-ceramic coating for aircraft is obtained.

[0062] Example 5

[0063] A method for preparing a corrosion-resistant nano-ceramic coating for aircraft includes the following steps:

[0064] Step 1: Weigh 22g of zirconia-alumina composite nano-ceramic powder (particle size 30nm) and add it to 200mL of deionized water. Disperse the powder ultrasonically at 40kHz frequency and 300W power for 35min. Transfer the powder to a 500mL three-necked flask and heat it to 80℃. Slowly add a mixed etching solution of 12g of 12% dilute nitric acid and 8g of 30% hydrogen peroxide. Stir the mixture at 250r / min for 2.5h. After the reaction, filter and wash the powder with deionized water until the pH of the filtrate is 7.0. Place the solid in a vacuum drying oven at 125℃ and dry it for 12h to obtain hydroxylated composite nano-ceramic powder.

[0065] Step 2: Weigh 20g of hydroxylated composite nano-ceramic powder and add it to 55g of anhydrous ethanol. Disperse the mixture ultrasonically at 40kHz frequency and 300W power for 20min. Adjust the pH of the system to 4.2 with glacial acetic acid. Add 1.6g of silane coupling agent KH-560 and place it in a 62℃ constant temperature water bath. Stir at 200r / min for 3.5h. After the reaction, centrifuge at 10000r / min for 15min, wash three times with anhydrous ethanol, and vacuum dry at 100℃ for 8h to obtain coupling agent modified ceramic powder.

[0066] Step 3: Weigh 23g of coupling agent modified ceramic powder and add it to 100g of N,N-dimethylformamide (DMF). Disperse the powder ultrasonically at 50kHz frequency and 400W power for 40min. Add 35g of trifluoroethyl acrylate (TFEA), 2g of allyl glycidyl ether and 3g of hydroxyethyl acrylate. Heat the mixture to 85℃ and add 0.5g of benzoyl peroxide (BPO). Purge the mixture with nitrogen three times to replace the air. Stir the mixture at 300r / min for 4h. Then cool the mixture to 60℃ and add 0.4g of diethylenetriamine. Continue stirring for 3h. Centrifuge at 10000r / min for 20min. Wash the mixture twice with DMF, once with ethanol and once with ethyl acetate. Dry the mixture under vacuum at 115℃ for 10h to obtain fluoropolymer resin modified nano-ceramic powder.

[0067] Step 4: Weigh 85g of allyl-modified bisphenol A epoxy resin (E-51-AM) and add it to 120g of a mixed solvent of DMF and ethyl acetate (mass ratio 1:1). Place the mixture in a 75℃ constant temperature water bath and stir at 300r / min for 90min to dissolve it. Add 4g of dispersant BYK-163, 2.5g of leveling agent BYK-333 and 1g of defoamer BYK-066, and continue stirring for 20min to obtain a uniform epoxy resin base.

[0068] Step 5: Cool the above epoxy resin base to 62℃, add 30g of acrylic polysiloxane resin, stir evenly, add 0.5g of BPO initiator, purge the air with nitrogen three times, heat to 87℃ and stir at 300r / min for 3.5h, then cool to 80℃, add 105g of isocyanate trimer curing agent (Desmodur N3390) and 0.2g of catalyst dibutyltin dilaurate (DBTDL), keep warm and react for 2.5h to obtain crosslinked modified matrix resin.

[0069] Step 6: Cool 280g of crosslinked modified matrix resin to 60℃, add 40g of fluoropolymer resin modified nano-ceramic powder and 2g of antioxidant 1010, ultrasonically disperse at 40kHz frequency and 300W power for 30min, then disperse at 12000r / min for 20min, and then transfer to a rotary evaporator for degassing under reduced pressure at 65℃ and -0.09MPa for 30min. Add 3g of polyamide wax thickener (BYK-410) to adjust the viscosity to... (25℃) After filtration through a 500-mesh filter, a corrosion-resistant nano-ceramic coating for aircraft is obtained.

[0070] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that steps 1, 2 and 3 are omitted, and the fluorinated polymer resin modified nano-ceramic powder in step 6 is replaced with nano-ceramic powder.

[0071] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that step 5 is omitted and the crosslinking modified matrix resin in step 6 is replaced with epoxy resin.

[0072] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that hydroxyethyl acrylate is not added in step 3.

[0073] Performance testing:

[0074] 1. Salt spray resistance test: The coatings prepared in each example and comparative example were uniformly applied to the surface of a 0.5mm thick cold-rolled steel sheet that had undergone rust removal, degreasing, and phosphating treatment. After curing, test samples with a dry film thickness of 50-100μm were obtained. The samples were placed in a salt spray test chamber, using a 5% sodium chloride solution as the spray medium. The chamber temperature was adjusted to 35℃, and continuous spraying was maintained. The surface of the samples was periodically observed for corrosion phenomena such as rust, blistering, and peeling. The time from the start of the test to the appearance of obvious corrosion defects was recorded as the salt spray resistance test result. The test results are shown in Table 1.

[0075] 2. Moisture and heat resistance test: Take the prepared coating test sample and place it in a moisture and heat test chamber. Set the temperature inside the chamber to 40℃ and the relative humidity to 95%. Maintain this environmental condition for continuous testing. During the test, periodically remove the sample to observe the surface condition and record the cumulative test time before abnormal phenomena such as blistering, discoloration, and peeling appear on the sample surface. This data is used as the moisture and heat resistance test data. The test results are shown in Table 1.

[0076] 3. Aviation fuel resistance test: The cured coating test sample was cut into 50mm×50mm sizes and completely immersed in RP-3 aviation fuel. The environment was maintained at room temperature (23±2℃). During immersion, the sample surface was periodically observed for any abnormalities such as swelling, wrinkling, peeling, or discoloration. The longest immersion time during which the sample remained without significant abnormalities was recorded as the aviation fuel resistance test result. The test results are shown in Table 1.

[0077] 4. Acid Resistance Test: Cut a 50mm × 50mm sample of the coating, seal the edges and back of the sample with plastic wrap (exposing only the coating surface), and completely immerse it in a 5% hydrochloric acid solution at room temperature (23±2℃) for 72 hours. After immersion, remove the sample, rinse it with deionized water, and dry it. Observe whether there are any corrosion phenomena such as blistering, swelling, peeling, or discoloration on the coating surface to evaluate the acid corrosion resistance. The test results are shown in Table 1.

[0078] 5. Alkali Resistance Test: After sealing the edges and back of a 50mm×50mm coating test sample, it was completely immersed in a 5% sodium hydroxide solution at room temperature (23±2℃) for 72 hours. After immersion, the sample was removed, rinsed with deionized water, and dried. The coating surface was then observed for any abnormalities such as blistering, swelling, peeling, or loss of gloss to assess its alkali corrosion resistance. The test results are shown in Table 1.

[0079] Table 1:

[0080]

[0081] 6. Hardness Test: The pencil hardness test was conducted using a standard Zhonghua brand pencil (ranging from 2H to 4H). The veneer was removed with a pencil sharpener to expose the lead (approximately 3mm in length). The lead was then vertically sanded flat on 400-grit sandpaper. The test sample was fixed horizontally, and the pencil was held at a 90° angle perpendicular to the sample surface. A constant pressure of 1kg was applied, and the pencil was used to scratch the coating surface at a speed of approximately 1mm / s, creating a 30mm long scratch. After each hardness test, the coating was observed for scratches or exposure of the substrate. The highest pencil hardness that did not produce noticeable scratches was taken as the coating hardness test result. The test results are shown in Table 2.

[0082] 7. Impact Resistance Test: The falling ball impact test was conducted. The coating test sample was fixed on the base of the impact tester with the coated surface facing upwards. A steel ball of a specified weight (1 kg) was dropped freely from a set height (50-75 cm) onto the center area of ​​the coating surface. After impact, the sample was removed, and the coating was observed for damage such as cracking, peeling, or blistering. The weight of the steel ball and the impact height were gradually adjusted, and the maximum impact energy (expressed in kg·cm²) that the coating could withstand without significant damage was recorded as the impact resistance test result. The test results are shown in Table 2.

[0083] Table 2:

[0084]

[0085] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a corrosion-resistant nano-ceramic coating for aircraft, characterized in that, Includes the following steps: S1. Zirconia-alumina composite nano-ceramic powder is added to deionized water, ultrasonically dispersed, then dilute nitric acid and hydrogen peroxide are added, the mixture is stirred and reacted, and after washing and drying, hydroxylated composite nano-ceramic powder is obtained. S2. The hydroxylated composite nano-ceramic powder was added to anhydrous ethanol, ultrasonically dispersed, pH adjusted, silane coupling agent KH-560 was added, the mixture was stirred and reacted, and after centrifugation, washing and drying, the coupling agent modified ceramic powder was obtained. S3. Add the coupling agent-modified ceramic powder to N,N-dimethylformamide, disperse it by ultrasonication, add trifluoroethyl acrylate, allyl glycidyl ether and benzoyl peroxide, introduce nitrogen gas, heat and stir to react, then cool down, add diethylenetriamine, continue stirring to react, and after centrifugation, washing and drying, obtain fluoropolymer resin-modified nano-ceramic powder. S4. Add allyl-modified bisphenol A epoxy resin to a mixed solvent of N,N-dimethylformamide and ethyl acetate, stir to dissolve, then add dispersant, leveling agent and defoamer, stir evenly to obtain epoxy resin base material; S5. Mix epoxy resin base material with acrylic polysiloxane resin, add benzoyl peroxide, introduce nitrogen gas, stir and react, then add isocyanate trimer curing agent and catalyst, stir and react to obtain crosslinked modified matrix resin. S6. The cross-linked modified matrix resin, fluoropolymer resin modified nano-ceramic powder, and antioxidant are mixed, ultrasonically dispersed, then high-speed dispersed, then degassed under reduced pressure, thickener is added to adjust the viscosity, and then filtered to obtain a corrosion-resistant nano-ceramic coating for aircraft.

2. The method for preparing a corrosion-resistant nano-ceramic coating for aircraft according to claim 1, characterized in that, In step S2, the mass ratio of hydroxylated composite nano-ceramic powder to silane coupling agent KH-560 is 10:(0.8~1.5).

3. The method for preparing a corrosion-resistant nano-ceramic coating for aircraft according to claim 1, characterized in that, In step S3, the mass ratio of trifluoroethyl acrylate to allyl glycidyl ether is 35:(2-5).

4. The method for preparing a corrosion-resistant nano-ceramic coating for aircraft according to claim 1, characterized in that, In step S3, hydroxyethyl acrylate is also added to N,N-dimethylformamide.

5. The method for preparing a corrosion-resistant nano-ceramic coating for aircraft according to claim 4, characterized in that, The mass ratio of trifluoroethyl acrylate to hydroxyethyl acrylate is 35:(3-6).

6. The method for preparing a corrosion-resistant nano-ceramic coating for aircraft according to claim 1, characterized in that, In step S5, the mass ratio of allyl modified bisphenol A epoxy resin to acrylic polysiloxane resin is 85:(30-38).

7. The method for preparing a corrosion-resistant nano-ceramic coating for aircraft according to claim 1, characterized in that, In step S6, the mass ratio of the cross-linked modified matrix resin to the fluoropolymerized resin modified nano-ceramic powder is 7:(1-2).

8. A corrosion-resistant nano-ceramic coating for aircraft, characterized in that, It is prepared by the method described in any one of claims 1-7.

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