A fairing with a hydrophobic structure, an anti-icing and corrosion-resistant coating of a fairing surface, and a preparation method and application thereof

Abstract

The application provides a fairing with a hydrophobic structure, an anti-icing and corrosion-resistant coating of a fairing surface and a preparation method and application thereof. The fairing is in a conical structure, a side conical surface of which extends out a plurality of umbrella surfaces from a conical tip downwards, and an outer surface of each umbrella surface is distributed with a texture morphology and / or an anti-icing and corrosion-resistant coating. The anti-icing and corrosion-resistant coating comprises, from inside to outside along an adhesion surface, a PTFE coating chemically modified with a sodium naphthalene treatment solution and a GO / PPS composite coating chemically modified with a fluorosilane treatment solution. The application can shorten the rolling distance of liquid drops on the surface by designing the plurality of umbrella surfaces, and is beneficial to the separation of liquid drops from the substrate. The laser texture designed on the surface of the substrate can increase the roughness and guide the flow to easily roll off. The multi-layer coating and the surface chemical modification treatment method can improve the adhesion of the coating, construct the surface micro-nano secondary structure and reduce the surface energy, so that the coating has excellent anti-icing and corrosion resistance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of surface engineering, and particularly relates to a fairing with a hydrophobic structure, an anti-icing and corrosion-resistant coating on the surface of the fairing, and a preparation method and application thereof. BACKGROUND

[0002] When the environment in which the aircraft is located is below freezing point, solid ice layers formed by supercooled rain and snow water covering the surface of the material are icing phenomena due to the influence of factors such as temperature and humidity. During flight, the air inlet of the engine of the aircraft continuously absorbs external gas. When the humidity of the external high-altitude environment is high and the temperature is low, the air absorbed by the air inlet of the engine contains a large amount of water, and the fairing and the like are prone to icing under low-temperature conditions. When the fairing of the air inlet of the engine is iced, the passage of the air inlet is reduced, and when the amount of gas obtained by the engine is insufficient, the rotation rate of the engine is greatly reduced, and even the engine stops working due to small power. On the other hand, due to the existence of air pressure difference, a large suction force is generated at the air flow passage of the engine, and the ice crystals adhering to the surface of the aircraft enter the engine through the action of the large suction force, causing the engine chuck or damage. When the aircraft is in service in the coastal area or in rainy weather, the fairing of the engine is in an atmospheric environment with high temperature, high humidity and high mold content, and is prone to failure problems such as mold corrosion. Therefore, providing a special structure of the fairing and preparing an anti-icing and corrosion-resistant functional coating on the surface has a positive significance for improving the service performance of the aircraft and the like.

[0003] The prior art provides a Ni-PTFE-SiC super-hydrophobic corrosion-resistant coating and a preparation method thereof. PTFE and SiC nanoparticles are added to a nickel-based plating solution, and a Ni-PTFE-SiC super-hydrophobic corrosion-resistant coating is prepared on a metal substrate by using an electrodeposition method, but the coating prepared by this method has high processing cost.

[0004] The prior art provides a magnesium alloy super-hydrophobic and active protection dual-functional composite corrosion-resistant coating and a preparation method thereof. The preparation method includes four steps, namely, a carrier material loaded with an corrosion inhibitor is prepared by a coprecipitation method; a primer layer is prepared by a hydrothermal method; modified SiO2 nanoparticles are prepared; and a topcoat layer is prepared by a spraying method to form a composite corrosion-resistant coating with super-hydrophobic and active protection dual functions. However, the preparation process is complex, and the processing cost is high.

[0005] The prior art provides a composite multi-layer hydrophobic corrosion-resistant film, a preparation method and application thereof. The film includes a first metal adhesion layer, a hydrogen-containing amorphous carbon film layer and a hydrogen-free amorphous carbon film layer from bottom to top, and is prepared by controlling the ratio of argon and hydrogen by a magnetron sputtering method. However, the prepared plating layer has uneven thickness and poor compactness.

[0006] Therefore, it is an urgent problem for those skilled in the art to construct a functional coating with high bonding strength and excellent anti-icing and corrosion resistance by using a method with engineering applicability and convenient operation. SUMMARY

[0007] The present application aims to provide a fairing with a hydrophobic structure. The fairing has a simple overall structure, reasonable design, long service life, and good anti-icing and corrosion resistance. The fairing provided by the present application can shorten the rolling distance of liquid droplets on the surface by designing multiple umbrella-shaped surfaces, and can also make the liquid droplets detach from the substrate as soon as possible under a small external force. And / or by designing laser texture on the surface of the substrate, the convex can increase the roughness and reduce the residence time of the liquid droplets, and the concave can guide the flow and facilitate the rolling of the liquid droplets.

[0008] Another object of the present application is to provide an anti-icing and corrosion-resistant coating on the surface of the fairing. By designing multiple layers of coating and using a surface chemical modification treatment method, the adhesion of the coating is improved, a surface micro-nano secondary structure is constructed, and the surface energy is reduced. The coating has both anti-icing and corrosion resistance, thereby solving the problems of water icing and corrosion in the medium on the surface of the engine fairing. Through the above multiple optimization design, the prepared fairing has excellent hydrophobic and corrosion-resistant effects, which can effectively improve the service performance of aircraft and other aircrafts.

[0009] To achieve the above object, the present application provides a fairing with a hydrophobic structure, which specifically comprises:

[0010] The fairing has a conical structure, and the side conical surface extends downward from the conical tip to form multiple umbrella-shaped surfaces. The outer surface of each umbrella-shaped surface is distributed with a texture morphology and / or an anti-icing and corrosion-resistant coating.

[0011] In a preferred embodiment, the texture morphology includes convex texture and concave texture,

[0012] The convex texture is arranged at the top of the umbrella-shaped surface formed by the conical tip,

[0013] The concave texture is arranged at the bottom of the umbrella-shaped surface formed by the conical tip and the outer surface of other umbrella-shaped surfaces.

[0014] In a preferred embodiment, the anti-icing and corrosion-resistant coating includes, from the inside to the outside along the adhesion surface, a PTFE coating chemically modified with a sodium naphthalene treatment solution and a GO / PPS composite coating chemically modified with a fluorosilane treatment solution.

[0015] In a preferred embodiment, the fluoro-silane treatment solution comprises one or more of perfluoroquaternary trimethoxysilane, perfluorodecyl triethoxysilane, perfluorooctyl triethoxysilane, perfluorooctyl trichlorosilane, dodecafluoroheptyl propyl trimethoxysilane, nonafluoro hexyl trimethoxysilane, nonafluoro hexyl triethoxysilane, trifluoro propyl methyl trimethoxysilane, trifluoro propyl triethoxysilane.

[0016] Another object of the present application is to provide a method for preparing an anti-icing and corrosion-resistant coating, which comprises preparing a multi-layer coating comprising polytetrafluoroethylene (PTFE), polyphenylene sulfide (PPS), graphene oxide (GO) and fluoro-silane, and respectively performing surface chemical modification on different coatings, thereby preparing a composite coating with excellent anti-icing and corrosion-resistant effects. The overall preparation method is simple and efficient, has low energy consumption, and uses safe and environmentally friendly raw materials, and is particularly suitable for large-scale industrial production.

[0017] To achieve the above object, the present application provides a method for preparing an anti-icing and corrosion-resistant coating, which specifically comprises the following steps:

[0018] (1) Material preparation: preparing a fairing substrate, preparing a coating A by dispersing a polytetrafluoroethylene emulsion in anhydrous ethanol, and preparing a coating B by dispersing polyphenylene sulfide and graphene oxide in fluoro-silane;

[0019] (2) Preparing a PTFE coating: uniformly spraying the coating A on the surface of the fairing substrate, drying, curing, and cooling to room temperature;

[0020] (3) Sodium naphthalene treatment: preparing a mixed solution by dispersing a sodium naphthalene treatment solution in tetrahydrofuran, soaking the coating prepared in step (2) in the prepared mixed solution, drying, and cooling to room temperature, and storing in the dark;

[0021] (4) Preparing a GO / PPS composite coating: uniformly spraying the coating B on the surface of the coating obtained in step (3), drying, curing, and cooling to room temperature;

[0022] (5) Fluoro-silane treatment: soaking the GO / PPS composite coating prepared in step (4) in a fluoro-silane treatment solution, drying, and cooling to room temperature.

[0023] In a preferred embodiment, in step (1), the mass fraction of graphene oxide in the coating B is 5-15%, and the mass fraction of fluoro-silane is 3-5%.

[0024] In a preferred embodiment, in steps (2) and (4), the curing conditions are as follows: increasing the temperature to 320-380℃ at a rate of 7-8℃ / min, and isothermally sintering for 20-40min.

[0025] In a preferred embodiment, the PTFE coating prepared in step (2) has a thickness of 30-40 μm; and the GO / PPS composite coating prepared in step (4) has a thickness of 200-220 μm.

[0026] In a preferred embodiment, the soaking time in step (3) is 20-30 s.

[0027] In step (5), the soaking time is 4-6 h.

[0028] Another object of the present application is to provide an application of the fairing with a hydrophobic structure in the field of aircraft deicing.

[0029] Compared with the prior art, the technical scheme of the present application has the following advantages:

[0030] (1) The structure of the present application is simple and reasonable, and has a long service life. The surface preparation method is simple and easy to operate, fast and efficient in production, low in requirements for equipment and energy consumption, and easy to control in the production process. Moreover, the raw materials are easy to obtain, safe and environmentally friendly, and the present application is especially suitable for large-scale popularization and application.

[0031] (2) The fairing provided by the present application can be prepared by one-piece molding, and has a conical structure as a whole. The conical surface is designed to be broken, so that the outer surface of the fairing forms a barb shape composed of multiple umbrella-shaped surfaces. The above-mentioned structure design can shorten the rolling distance of liquid droplets on the surface as much as possible. When the liquid droplets adhere to the surface of the fairing, they can roll off the surface as soon as possible under the action of a small external force, reducing the contact time of the liquid droplets with the fairing, thereby delaying the occurrence of icing and corrosion.

[0032] (3) The fairing provided by the present application is respectively laser textured on the surfaces of the multiple umbrella-shaped surfaces, and a boss texture pattern is constructed on the top of the umbrella-shaped surface formed at the tip of the cone, so as to increase the roughness and reduce the residence time of liquid droplets. A groove texture pattern is constructed at the bottom of each umbrella-shaped surface, so that the bottom of the umbrella-shaped surface has a guiding ability, and the liquid droplets can be separated from the surface under the action of a small external force during rotation.

[0033] (4) The method for preparing the composite coating of the present application is to spray the PTFE coating directly on the surface of the substrate, and the PTFE coating is used as the first layer coating, so that the excellent corrosion resistance of PTFE can be fully utilized, and the corrosion medium can be effectively prevented from invading the metal substrate to achieve the protection effect. After the sodium naphthalene treatment, the C-F bond in the PTFE is destroyed and the hydroxyl group is introduced, so that the coating is changed from difficult adhesion to adhesion, and the adhesion between the organic coating and the metal substrate is enhanced, and at the same time, the foundation for the second layer coating is laid. In addition, the silanization treatment is carried out again after the second layer coating, so that the surface energy of the composite coating can be reduced, and the anti-icing and corrosion resistance of the coating can be further ensured and optimized.

[0034] (5) The PPS with excellent anti-icing and corrosion resistance and the GO with excellent mechanical properties are combined as the protective coating for the first time in the present application, so that the anti-icing and corrosion resistance is ensured while the service durability is ensured. After the fluorosilane is added, the silanol groups in the fluorosilane and the hydroxyl groups on the surface of the PTFE are subjected to dehydration condensation reaction, and are connected to the surface of the PTFE through covalent bond, and the amino functional groups at the other end of the silane coupling agent and the epoxy functional groups in the GO are subjected to ring-opening reaction, so that the GO and the PTFE are closely connected together through the fluorosilane. After the surface grafting, the micro-nano secondary structure is formed, and the anti-icing and corrosion resistance of the coating is further enhanced. BRIEF DESCRIPTION OF DRAWINGS

[0035] These and / or other aspects and advantages of the present application will become more apparent and more readily appreciated from the following detailed description of the embodiments of the present application, taken in conjunction with the accompanying drawings in which:

[0036] Figure 1 is a schematic diagram of the rectifier cover in Example 1 of the present application;

[0037] Figure 2 is a schematic diagram of the laser texturing at the top of the umbrella surface in Example 1 of the present application;

[0038] Figure 3 is a schematic diagram of the laser texturing at the bottom of the umbrella surface in Example 1 of the present application;

[0039] Figure 4 is a micro-morphology diagram of the coating in Effect Example 1 of the present application;

[0040] Figure 5 is a static contact angle diagram of the coating surface in Effect Example 1 of the present application;

[0041] Figure 6 is an icing time diagram of the coating at different temperatures in Effect Example 1 of the present application;

[0042] Figure 7Figure 1 is a comparison chart of the mycelium corrosion effect of the base body and the coating layer in the effect example 1 of the present application, wherein (a) is the mycelium growth condition of the surface of the base body without coating layer, and (b) is the mycelium growth condition of the surface of the coating layer.

[0043] Explanation of main reference signs:

[0044] 1 - umbrella top, 2 - umbrella bottom, 3 - boss laser texture, 4 - groove laser texture. DETAILED DESCRIPTION

[0045] In order for those skilled in the art to better understand the present application, the present application will be further described in detail below in combination with the drawings and specific embodiments, but it should be understood that the protection scope of the present application is not limited by the specific embodiments.

[0046] The hydrophobic structure of the fairing, the surface anti-icing and corrosion resistant coating and the preparation method and application thereof provided by the embodiments of the present application solve the problems of complex process, poor compactness and bonding force of the prepared coating, and poor anti-icing and corrosion resistance in the prior art.

[0047] The technical solution in the present application is to solve the above problems, and the general idea is as follows:

[0048] The purpose of the present application is to provide a fairing with a hydrophobic structure. The fairing has a simple overall structure, reasonable design, long service life, and good anti-icing and corrosion resistance. The fairing provided by the present application can shorten the rolling distance of liquid droplets on the surface by designing multiple umbrella-shaped surfaces, and can also make the liquid droplets quickly separate from the base body under a small external force. And / or by designing laser texture on the surface of the base body, the boss can increase the roughness and reduce the liquid droplet residence time, and the groove can guide the liquid droplets to roll off.

[0049] To achieve the above purpose, the present application provides a fairing with a hydrophobic structure, which specifically comprises:

[0050] The fairing is in a conical structure, and the side conical surface extends out multiple umbrella-shaped surfaces from the conical tip downward. The outer surface of each umbrella-shaped surface is distributed with texture topography and / or anti-icing and corrosion resistant coating.

[0051] In a preferred embodiment, the material of the fairing has no effect on the purpose of the present application, and suitable materials mastered by those skilled in the art can be used. Preferably, the material is an alloy, and the base body material of the fairing used in the embodiments of the present application is an aluminum alloy.

[0052] In a preferred embodiment, the texture topography includes boss texture and groove texture,

[0053] The boss texture is arranged on the umbrella-shaped surface top formed by the conical tip,

[0054] The groove texture is arranged on the bottom of the umbrella surface formed by the cone tip and other outer surfaces of the umbrella surface.

[0055] In a preferred embodiment, the texture topography is prepared by using a nanosecond pulsed laser device.

[0056] More preferably, the processing parameters of the texture topography are as follows: pulse width 100 ns, frequency 85 kHz, pulse energy 0.5 mJ, average power 37.5 Kw, powder feeding speed 3 rpm, and processing times 1-3 times.

[0057] The prepared umbrella surface top texture has a diameter of 50-70 μm, a texture center distance of 200-220 μm, and a height of 10 μm.

[0058] The prepared umbrella surface bottom and other outer surface textures have a diameter of 50-70 μm, a texture center distance of 200-220 μm, and a depth of 10 μm.

[0059] In a preferred embodiment, the umbrella surface top formed by the cone tip specifically refers to arranging boss textures on the outer surface region at 1 / 3 of the cone tip to the umbrella tip.

[0060] The umbrella surface bottom formed by the cone tip specifically refers to arranging groove textures on the outer surface region at 1 / 3 of the umbrella tip to the cone tip.

[0061] Preferably, the other outer surface of the umbrella surface specifically refers to arranging groove textures on the region that cannot be covered by the previous umbrella surface; more preferably, the other outer surface of the umbrella surface specifically refers to arranging groove textures on the region that cannot be covered by the vertical projection of the previous umbrella surface.

[0062] Another object of the present application is to provide an anti-icing and corrosion-resistant coating for the surface of a fairing. By designing a multi-layer coating and using a surface chemical modification treatment method, the adhesion of the coating is improved, a surface micro-nano secondary structure is constructed, and the surface energy is reduced. The coating has both anti-icing and corrosion resistance, thereby solving the problems of water icing and corrosion in media on the surface of the engine fairing. After the above-mentioned multiple optimization designs, the prepared fairing has excellent hydrophobicity and corrosion resistance, which can effectively improve the service performance of aircraft and other aircrafts.

[0063] To achieve the above object, the present application provides an anti-icing and corrosion-resistant coating, which specifically comprises:

[0064] The anti-icing and corrosion-resistant coating comprises, from inside to outside along the adhesion surface, a PTFE coating chemically modified by a sodium naphthalene treatment solution and a GO / PPS composite coating chemically modified by a fluoro-silane treatment solution.

[0065] In a preferred embodiment, the fluoro-silane treatment solution comprises one or more of perfluoroquaternary trimethoxysilane, perfluorodecyl triethoxysilane, perfluorooctyl triethoxysilane, perfluorooctyl trichlorosilane, dodecafluoroheptyl propyl trimethoxysilane, nonafluorohexyl trimethoxysilane, nonafluorohexyl triethoxysilane, trifluoropropyl methyl trimethoxysilane, trifluoropropyl triethoxysilane.

[0066] Another object of the present application is to provide a method for preparing an anti-icing and corrosion-resistant coating, which comprises preparing a multilayer coating comprising polytetrafluoroethylene (PTFE), polyphenylene sulfide (PPS), graphene oxide (GO) and fluoro-silane, and respectively performing surface chemical modification on different coatings, thereby preparing a composite coating with excellent anti-icing and corrosion-resistant effects. The overall preparation method is simple and efficient, has low energy consumption, and uses safe and environmentally friendly raw materials, and is particularly suitable for large-scale industrial production.

[0067] To achieve the above object, the present application provides a method for preparing an anti-icing and corrosion-resistant coating, which specifically comprises the following steps:

[0068] (1) Material preparation: preparing a fairing substrate, preparing a coating A by dispersing a polytetrafluoroethylene emulsion in anhydrous ethanol, and preparing a coating B by dispersing polyphenylene sulfide and graphene oxide in fluoro-silane;

[0069] (2) Preparing a PTFE coating: uniformly spraying the coating A on the surface of the fairing substrate, drying, curing, and cooling to room temperature;

[0070] (3) Sodium naphthalene treatment: dispersing a sodium naphthalene treatment solution in tetrahydrofuran to prepare a mixed solution, immersing the coating prepared in step (2) in the prepared mixed solution, drying, cooling to room temperature, and storing in the dark;

[0071] (4) Preparing a GO / PPS composite coating: uniformly spraying the coating B on the surface of the coating obtained in step (3), drying, curing, and cooling to room temperature;

[0072] (5) Fluoro-silane treatment: immersing the GO / PPS composite coating prepared in step (4) in a fluoro-silane treatment solution, drying and cooling to room temperature.

[0073] In a preferred embodiment, in step (1), the preparation of the fairing substrate is the conical structure and the multilayer umbrella-shaped surface of the manufactured fairing, and the specific process can adopt conventional mechanical manufacturing methods mastered by those skilled in the art, which can achieve the object of the present application, and therefore will not be limited herein. More preferably, the fairing substrate is prepared by an integral molding method. By integral molding, the waterproof performance of the fairing can be improved. In the embodiments of the present application, the fairing workpiece is processed and prepared by a lost wax casting process.

[0074] In a preferred embodiment, after the preparation of the fairing substrate in step (1), a substrate pretreatment step is further included. The purpose of the substrate pretreatment is to remove the surface oxide layer of the substrate, to obtain a certain cleanliness and roughness of the substrate surface, to improve the mechanical properties and to improve the adhesion between the coating. Therefore, the pretreatment method can be any method known to those skilled in the art, as long as it can achieve the above-mentioned purposes. Preferably, the substrate pretreatment step is: dissolving the grease on the surface of the substrate with an organic solvent, heating to volatilize the organic solvent, and then treating the substrate by polishing or sandblasting for 10-12 min.

[0075] In a preferred embodiment, after step (1) is completed, a nanosecond pulsed laser device can be used to process and prepare the textured morphology. The specific preparation method and texture position are as described above. That is, the anti-icing and corrosion-resistant coating provided by the present application can be covered on the surface of the fairing substrate or the surface of the fairing substrate with textured morphology.

[0076] In a preferred embodiment, in step (1), the amount of anhydrous ethanol in the coating A can be used to uniformly disperse the polytetrafluoroethylene emulsion. During the subsequent sintering and curing process for preparing the coating, the anhydrous ethanol will volatilize, so its amount is not specifically limited. Preferably, in the coating A, the mass fraction of polytetrafluoroethylene is 40-50%, i.e., the mass of polytetrafluoroethylene accounts for 40-50% of the total mass of polytetrafluoroethylene and anhydrous ethanol. More preferably, in the coating A, the mass fraction of polytetrafluoroethylene is 45-50%. In the embodiments of the present application, the mass fraction of polytetrafluoroethylene in the coating A is 45%.

[0077] In a preferred embodiment, in step (1), the mass fraction of graphene oxide in the coating B is 5-15%, and the mass fraction of fluorosilane is 3-5%, i.e., the mass of graphene oxide and fluorosilane accounts for 5-15% and 3-5% of the total mass of graphene oxide, polyphenylene sulfide and fluorosilane, respectively.

[0078] In a preferred embodiment, in step (1), the fluorosilane in the coating B includes one or more of perfluoroquaternary trimethoxysilane, perfluorodecyl triethoxysilane, perfluorooctyl triethoxysilane, perfluorooctyl trichlorosilane, dodecafluoroheptyl propyl trimethoxysilane, nonafluoroheptyl trimethoxysilane, nonafluoroheptyl triethoxysilane, trifluoropropyl methyl trimethoxysilane, and trifluoropropyl triethoxysilane.

[0079] In a preferred embodiment, in step (1), to improve the spraying effect of the coating B, anhydrous ethanol can also be added to dilute the prepared coating B, and meanwhile, the anhydrous ethanol is only used as a diluent for easy spraying, and will be completely volatilized in subsequent processing without affecting the performance of the coating, so that the amount is not specifically limited; preferably, the mass ratio of the coating B to the anhydrous ethanol is 1: (2-5), and in the embodiment of the present application, the mass ratio of the coating B to the anhydrous ethanol is 1:3.

[0080] In a preferred embodiment, in step (1), in the preparation process of the coating A and the coating B, a magnetic stirrer is respectively used for stirring for 30-40 min to be uniform.

[0081] In a preferred embodiment, in steps (2) and (4), the spraying conditions can be conditions mastered by those skilled in the art, and the coating can be uniformly sprayed; preferably, the spraying conditions are as follows: the spraying gun pressure is 0.3-0.5 MPa, the gun mouth distance from the substrate is 20-40 cm, and the spraying angle is 45°. Under the above conditions, the coating can be atomized and uniformly sprayed on the surface of the substrate to be coated. The spraying device can be mastered by those skilled in the art, and in the embodiment of the present application, the ANESTIWATAW-71 spraying gun is used.

[0082] In a preferred embodiment, in steps (2) and (4), the drying is to make the coating preliminarily dry and then solidified and formed, so that the specific drying method and device can be mastered by those skilled in the art; preferably, the drying conditions are as follows: the workpiece coated with the PTFE coating or the composite coating is placed in a drying box and dried at 80-100℃ for 10-20 min.

[0083] In a preferred embodiment, in steps (2) and (4), the solidification conditions are as follows: the temperature is raised at a rate of 7-8℃ / min to 320-380℃, and the temperature is kept constant for sintering for 20-40 min.

[0084] In a preferred embodiment, in step (2), the thickness of the prepared PTFE coating is 30-40μm.

[0085] In a preferred embodiment, in step (3), the mass ratio of the sodium naphthalene treatment solution to tetrahydrofuran is 1: (10-20), and in the embodiment of the present application, the mass ratio of the sodium naphthalene treatment solution to tetrahydrofuran is 1:15.

[0086] In a preferred embodiment, in step (3), the prepared PTFE coating is soaked in the sodium naphthalene solution for 20-30 s.

[0087] In a preferred embodiment, in step (3), the drying method and device are any method and device known to those skilled in the art, preferably, drying at 70-80 DEG C for 50-60 min.

[0088] In the present application, the treatment with sodium naphthalene destroys the C-F bond in PTFE and introduces hydroxyl groups, so that the coating changes from difficult adhesion to adhesion, enhancing the bonding force of the organic coating and the metal substrate, and laying a foundation for the second coating, improving the bonding effect between the coatings.

[0089] In a preferred embodiment, the GO / PPS composite coating prepared in step (4) has a thickness of 200-220 μm.

[0090] In a preferred embodiment, in step (5), the prepared composite coating is soaked in a fluoro-silane treatment solution for 4-6 h.

[0091] In a preferred embodiment, in step (5), the drying method and device are any method and device known to those skilled in the art, preferably, drying at 100-120 DEG C for 40-60 min.

[0092] In the present application, the GO / PPS composite coating is chemically modified by fluoro-silane, which can reduce the surface energy of the composite coating, and further ensure and optimize the anti-icing and corrosion resistance of the coating.

[0093] In the present application, the PTFE coating and the composite coating are sequentially constructed, which can hinder the invasion of corrosive medium into the substrate, and after chemical modification, the interface bonding strength of the coating is enhanced. In the composite coating, the silanol groups in fluoro-silane and the hydroxyl groups on the surface of PTFE undergo dehydration condensation reaction, and are connected to the surface of PTFE through covalent bond, and the amino functional groups at the other end of the silane coupling agent and the epoxy functional groups in GO undergo ring-opening reaction, and GO and PTFE are tightly connected together through fluoro-silane. The composite coating material itself has excellent anti-icing performance, and after surface chemical treatment, a micro-nano secondary structure is formed, the roughness is increased, liquid droplets can be avoided to stay on the surface of the coating, and the anti-icing and corrosion resistance are further improved.

[0094] Another object of the present application is to provide a hydrophobic structure of a fairing for use in the field of aircraft ice prevention. The present application optimizes the overall structure of the fairing, performs laser texturing on the surface of the fairing substrate, prepares an anti-icing and corrosion-resistant coating, and uses a targeted surface chemical modification method, so that the prepared coating can effectively avoid liquid droplets to contact, condense and accumulate on the surface of the coating, thereby avoiding icing and corrosion, and especially can adapt to the complex working conditions of the aircraft.

[0095] The technical solutions of the present application will be described in detail below through specific embodiments.

[0096] Unless otherwise specified, the technical means used in the present application are conventional means known to those skilled in the art, and various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or prepared by existing methods. The reagents used in the present application are analytical pure unless otherwise specified.

[0097] The naphthalene sodium treatment solution used in the embodiments of the present application is model ZN-711, purchased from Guangzhou Zhuo Neng Trade Co., Ltd. The polytetrafluoroethylene used is PTFE emulsion (60 wt.%), purchased from Shanghai San Aif New Material Co., Ltd. The polyphenylene sulfide used is powder (300 mesh), purchased from Zhejiang Xinhengcheng Special Material Co., Ltd. The graphene oxide used is powder (1100 mesh), purchased from Dazhan Nanometer (Guangdong) Co., Ltd. The fluoro-silane emulsion and fluoro-silane treatment solution used are both perfluoroquaternary trimethoxysilane, purchased from Quzhou Dongye Chemical Co., Ltd.

[0098] In the present application, the normal temperature is 25℃±5℃.

[0099] In the present application, the weight parts can be weight units known in the art such as μg, mg, g, kg, etc., and can also be multiples thereof such as 1 / 10, 1 / 100, 10 times, 100 times, etc.

[0100] Example One

[0101] An engine cowling structure and a preparation method of a surface anti-icing and corrosion-resistant coating thereof, comprising the following steps:

[0102] 1. Workpiece pretreatment

[0103] In order to make the workpiece coating have sufficient surface adhesion, the oil on the surface of the workpiece is dissolved using acetone and heated to about 380℃ to volatilize, and sand blasting is performed to remove the surface oxide layer, so that the substrate surface obtains a certain cleanliness and roughness, improves the mechanical properties and improves the adhesion between the coating and the substrate.

[0104] 2. Groove laser texturing

[0105] A nanosecond pulsed laser device is used to prepare laser texture on the outer surface of the conical cowling with a multilayer umbrella-shaped surface, and the process parameters are as follows: pulse width 100 ns, frequency 85 kHz, pulse energy 0.5 mJ, average power 37.5 Kw, powder feeding speed 3 rpm, and processing times 1.

[0106] A boss texture with a texture diameter of 50 μm, a texture center distance of 200 μm and a height of 10 μm is prepared on the top of the umbrella-shaped surface formed by the cone tip.

[0107] The grooved texture with a diameter of 50 μm, a texture interval of 200 μm and a depth of 10 μm is prepared on the bottom of the umbrella surface formed by the tip of the cone and the outer surface of the umbrella surface.

[0108] 3. Preparation of the first layer of paint (Paint A)

[0109] 100 parts by weight of PTFE emulsion (60 wt.%) is added to anhydrous ethanol, and each paint is stirred for 30 min by a magnetic stirrer until uniformly dispersed.

[0110] 4. Preparation of the second layer of paint (Paint B)

[0111] 5 parts by weight of GO powder, 3 parts by weight of fluorosilane emulsion and 92 parts by weight of PPS powder are diluted with anhydrous ethanol, and each paint is stirred for 30 min by a magnetic stirrer until uniformly dispersed.

[0112] 5. Spraying

[0113] The first layer of paint is loaded into an ANESTI WATA W-71 spray gun, and the paint is uniformly sprayed on the surface of the workpiece by the spray gun. During the spraying process, the pressure of the spray gun is 0.3 MPa, the distance between the nozzle of the spray gun and the workpiece is 20 cm, and the spraying angle is 45°.

[0114] 6. Drying

[0115] The workpiece coated with the composite coating is placed in a drying oven and dried at 80°C for 10 min.

[0116] 7. Sintering

[0117] The sprayed composite coating is placed in a box-type curing oven for curing treatment. The temperature is gradually increased to 320°C within 40 min and then sintered at a constant temperature for 20 min. After cooling in air, the first layer of PTFE coating with a thickness of about 30 μm is obtained. PTFE has hydrophobic and corrosion-resistant properties, and the PTFE coating can hinder the intrusion of corrosive media into the substrate.

[0118] 8. Sodium naphthalene treatment

[0119] 1 part by weight of sodium naphthalene treatment solution is added to 15 parts by weight of tetrahydrofuran solution, and the PTFE coating prepared in step 7 is soaked in the sodium naphthalene solution for 20 s, dried at 70°C for 50 min, cooled to room temperature, and stored under light shielding. After sodium naphthalene treatment, the C-F bond in PTFE is broken and hydroxyl groups are introduced, making the coating change from difficult adhesion to easy adhesion, enhancing the bonding force of the organic coating to the metal substrate, and laying a foundation for the second layer of coating.

[0120] 9. Preparation of the second layer of coating

[0121] The above steps 5-7 were repeated with a second coating to obtain a GO / PPS composite coating with a thickness of 200 pm. The silanol groups in the fluorosilane and the hydroxyl groups on the surface of the PTFE undergo a dehydration condensation reaction and are covalently bonded to the surface of the PTFE. The amino functional groups at the other end of the silane coupling agent undergo ring-opening reaction with the epoxy functional groups in the GO, and the GO and the PTFE are tightly connected together through the fluorosilane. The surface of the prepared coating has a micro-nano secondary structure and has a large roughness, which can delay icing and corrosion.

[0122] 10. Silanization treatment

[0123] The prepared composite coating was soaked in a fluorosilane treatment solution for 4 h and dried at 100° for 40 min and cooled to room temperature. The surface energy of the composite coating was reduced, and the anti-icing and corrosion resistance of the coating was further ensured and optimized.

[0124] Effect Example One

[0125] To verify the performance of the anti-icing and corrosion resistant coating, Effect Example One was designed. The difference from Example 1 is only that step 2 is omitted, i.e. the coating is prepared directly on the surface of the workpiece after step 1 pretreatment, to test the anti-icing and corrosion resistance of the coating itself.

[0126] (I) Micro-morphology

[0127] The microstructure of the coating prepared on the surface of the fairing is shown in Figure 4 It can be seen that the surface material of the coating is uniformly distributed and has good density, and there are some spherical protrusions, forming a micro-nano secondary structure and improving the surface roughness of the coating.

[0128] (II) Hydrophobic performance test

[0129] Test method: Under room temperature conditions, the static water contact angle (WCA) of the coating was measured using an FTA scientific droplet method interfacial tension meter and a contact angle meter. A droplet of deionized water (about 5 pL) was dropped on the surface of the coating using a needle tube, and the contact angle was measured after the droplet was stable.

[0130] The static water contact angle of the surface of the coating is shown in Figure 5 The contact angle is 150.3°, reaching the super-hydrophobic performance index, and having good hydrophobic performance. The liquid droplet and the coating are in a Cassie state of easy-to-roll gas, liquid and solid three-phase contact, so the liquid droplet separates from the surface of the coating in the form of bouncing before freezing.

[0131] (III) Anti-icing performance test

[0132] Test Method: The freezing time of supercooled water on the coating surface at different temperatures was measured using a DW-40 low-temperature test chamber. First, the test chamber was set to the required temperature. The coating to be tested was placed in the chamber and stabilized for 30 minutes. Simultaneously, deionized water was placed in the chamber to prepare supercooled water. Approximately 5 μL of supercooled water was taken using a dropper and dripped onto the surface of the coating. Timing was started, and the changes during the freezing process were observed and recorded using a high-definition camera. The freezing was considered complete when the droplet changed from a transparent dome shape to a cloudy, pointed cone shape, and timing was stopped.

[0133] The result is as follows Figure 6 As shown in the figure, the freezing process of droplets can be observed, demonstrating the ability to delay freezing under different low-temperature environments. This is because the droplets have a large contact angle when adhering to the coating surface, reducing the contact area between the droplets and the coating and decreasing the possibility of heterogeneous nucleation. The air or other media trapped in the surface structure act as thermal resistance, hindering energy transfer between the droplets and the coating, thus delaying freezing and creating time for the droplets to detach from the surface.

[0134] (iv) Test for resistance to mold and corrosion

[0135] Test Method: Spore suspensions were prepared from fungal strains stored at 6℃±4℃ for no more than 4 months. The spore suspensions consisted of *Aspergillus niger*, *Aspergillus terreus*, *Penicillium wansii*, *Penicillium cordifolium*, *Penicillium ochreae*, *Trichoderma breviculatum*, and *Trichoderma viride*. The suspensions were incubated at 30℃ for 10 days. The incubated suspensions were then sprayed onto the sample surface for a 28-day mold corrosion experiment. During this period, the relative humidity was maintained at 70%, and the temperature inside the test chamber was maintained at 30±1℃, which is optimal for mold growth. The mold growth on the sample surface was observed through photographs.

[0136] The result is as follows Figure 7 As shown in the figures, (a) represents the mold growth on the uncoated substrate surface, and (b) represents the mold growth on the coated surface. Figure (a) shows a clear, loosely distributed colony on the substrate surface, accompanied by the spread of hyphae, indicating vigorous growth. According to the mold test results evaluation standard of the "Environmental Testing Methods for Military Equipment," the mold growth level is 2. In contrast, as shown in Figure (b), no mold adheres or grows on the coated surface, resulting in a mold growth level of 0. The coating has excellent hydrophobic properties, making it difficult for moisture to accumulate on the surface in humid environments, thus preventing the formation of an environment conducive to mold growth and reproduction. The stable CF bonds in PTFE tightly surround the carbon atoms on the inside, preventing the coating from providing the nutrients needed for mold growth and reproduction. Therefore, the coating has excellent resistance to mold corrosion and can effectively protect the metal substrate.

[0137] Example 2

[0138] An engine cowling structure and a method for preparing a surface anti-icing corrosion-resistant coating thereof, comprising the following steps:

[0139] 1. Workpiece pretreatment

[0140] In order to make the workpiece coating have sufficient surface adhesion, the oil on the surface of the workpiece is dissolved using acetone and heated to about 380°C to volatilize, and sand blasting is performed to remove the surface oxide layer, so that the substrate surface has a certain cleanliness and roughness, the mechanical properties are improved, and the adhesion between the coating and the substrate is improved.

[0141] 2. Groove laser texturing

[0142] A nanosecond pulsed laser device is used to prepare laser texturing on the outer surface of the conical cowling with a multilayer umbrella-shaped surface, and the process parameters are as follows: pulse width 100 ns, frequency 85 kHz, pulse energy 0.5 mJ, average power 37.5 Kw, powder feeding speed 3 rpm, and processing times 2 times.

[0143] A boss texture with a texture diameter of 60 μm, a texture center distance of 210 μm, and a height of 10 μm is prepared on the top of the umbrella-shaped surface formed by the cone tip.

[0144] A groove texture with a diameter of 60 μm, a texture pitch of 210 μm, and a depth of 10 μm is prepared on the bottom of the umbrella-shaped surface formed by the cone tip and the outer surface of the other umbrella-shaped surface.

[0145] 3. Preparation of the first layer of coating (coating A)

[0146] 100 parts by weight of PTFE emulsion (60 wt.%) are added to anhydrous ethanol, and each coating is stirred using a magnetic stirrer for 35 min until it is uniformly dispersed.

[0147] 4. Preparation of the second layer of coating (coating B)

[0148] 10 parts by weight of GO powder, 4 parts by weight of fluorosilane emulsion, and 86 parts by weight of PPS powder are diluted with anhydrous ethanol, and each coating is stirred using a magnetic stirrer for 35 min until it is uniformly dispersed.

[0149] 5. Spraying

[0150] The first layer of coating is loaded into an ANESTIWATAW-71 spray gun, and the coating is uniformly sprayed on the surface of the workpiece using the spray gun. During the spraying process, the spray gun pressure is 0.4 MPa, the distance between the gun mouth and the workpiece is 30 cm, and the spraying angle is 45°.

[0151] 6. Drying

[0152] The workpiece coated with the composite coating is placed in a drying oven and dried at 90°C for 15 min.

[0153] 7. Sintering

[0154] The sprayed composite coating is placed in a box-type curing oven for curing treatment, gradually heated to 340℃ within 45 min and then sintered at constant temperature for 30 min, and after cooling in air, a first layer of PTFE coating is obtained, with a thickness of about 35 μm. PTFE has hydrophobicity and corrosion resistance, and the PTFE coating can hinder the intrusion of corrosive media into the substrate.

[0155] 8、Sodium naphthalene treatment

[0156] 1 part by weight of sodium naphthalene treatment solution is added to 15 parts by weight of tetrahydrofuran solution, and the PTFE coating prepared in step 7 is soaked in the sodium naphthalene solution for 25 s, dried at 75℃ for 55 min, cooled to room temperature, and stored under light shielding for standby. The sodium naphthalene treatment destroys the C-F bond in PTFE and introduces hydroxyl groups, so that the coating changes from difficult adhesion to adhesion, enhancing the bonding force of the organic coating to the metal substrate, and at the same time laying the foundation for the second layer of coating.

[0157] 9、Preparation of the second layer of coating

[0158] The above steps 5-7 are repeated with the second coating to obtain a GO / PPS composite coating, with a coating thickness of 210 μm. The silanol groups in fluorosilane undergo dehydration condensation reaction with the hydroxyl groups on the surface of PTFE, and are connected to the surface of PTFE through covalent bonds. The amino functional groups at the other end of the silane coupling agent undergo ring-opening reaction with the epoxy functional groups in GO, tightly connecting GO and PTFE together through fluorosilane. The prepared coating surface has a micro-nano secondary structure and has a large roughness, which can delay icing and corrosion.

[0159] 10、Silanization treatment

[0160] The prepared composite coating is soaked in a fluorosilane treatment solution for 5 h and dried at 110° for 50 min, and then cooled to room temperature. The surface energy of the composite coating is reduced, further ensuring and optimizing the anti-icing and corrosion resistance of the coating.

[0161] Example Three

[0162] An engine cowling structure and a method for preparing a surface anti-icing and corrosion resistant coating thereon, comprising the following steps:

[0163] 1、Workpiece pretreatment

[0164] In order to make the workpiece coating have sufficient surface adhesion, the oil on the surface of the workpiece is dissolved with acetone and heated to about 380℃ to volatilize, and the workpiece is sandblasted to remove the surface oxide layer, so that the substrate surface has a certain cleanliness and roughness, improves the mechanical properties and improves the adhesion between the coating and the substrate.

[0165] 2、Groove laser texturing

[0166] The outer surface of the conical fairing with multi-layer umbrella surface is prepared for laser texturing by using nanosecond pulse laser equipment, and the process parameters are as follows: pulse width 100 ns, frequency 85 kHz, pulse energy 0.5 mJ, average power 37.5 Kw, powder feeding speed 3 rpm, and processing times 3 times.

[0167] The boss texture with a diameter of 70 μm, a texture center distance of 220 μm, and a height of 10 μm is prepared on the top of the umbrella surface formed by the cone tip.

[0168] The groove texture with a diameter of 70 μm, a texture distance of 220 μm, and a depth of 10 μm is prepared on the bottom of the umbrella surface formed by the cone tip and the outer surface of other umbrella surfaces.

[0169] 3. Preparation of the first layer of paint (paint A)

[0170] 100 parts by weight of PTFE emulsion (60 wt.%) are added to anhydrous ethanol, and each paint is stirred for 40 min to disperse uniformly by using a magnetic stirrer.

[0171] 4. Preparation of the second layer of paint (paint B)

[0172] 15 parts by weight of GO powder, 5 parts by weight of fluorosilane emulsion, and 80 parts by weight of PPS powder are diluted with anhydrous ethanol, and each paint is stirred for 40 min to disperse uniformly by using a magnetic stirrer.

[0173] 5. Spraying

[0174] The first layer of paint is loaded into an ANESTI WATA W-71 spray gun, and the paint is uniformly sprayed on the surface of the workpiece by using the spray gun. During the spraying process, the spray gun pressure is 0.5 MPa, the distance between the gun mouth and the workpiece is 40 cm, and the spraying angle is 45°.

[0175] 6. Drying

[0176] The workpiece coated with the composite coating is placed into a drying box and dried at 100 ℃ for 20 min.

[0177] 7. Sintering

[0178] The sprayed composite coating is placed into a box-type curing oven for curing treatment, and gradually heated to 380 ℃ within 48 min and then sintered at constant temperature for 30 min. After cooling in air, the first layer of PTFE coating with a thickness of about 40 μm is obtained. The PTFE has hydrophobicity and corrosion resistance, and the PTFE coating can hinder the invasion of corrosive medium into the substrate.

[0179] 8. Sodium naphthalene treatment

[0180] The PTFE coating prepared in step 7 was immersed in the sodium naphthalene solution prepared in 15 parts by weight of tetrahydrofuran solution for 30 s, dried at 80 °C for 60 min, cooled to room temperature, and stored under light shielding for standby. The C-F bond in the PTFE was broken and hydroxyl groups were introduced after the sodium naphthalene treatment, so that the coating was changed from difficult adhesion to adhesion, the bonding force between the organic coating and the metal substrate was enhanced, and the foundation for the second coating was laid.

[0181] 9. Preparation of the second coating layer

[0182] The above steps 5-7 were repeated with the second coating to obtain a GO / PPS composite coating with a thickness of 220 μm. The silanol groups in the fluorosilane and the hydroxyl groups on the surface of the PTFE underwent dehydration condensation reaction, and were covalently bonded to the surface of the PTFE. The amino functional groups at the other end of the silane coupling agent and the epoxy functional groups in the GO underwent ring-opening reaction, and the GO and the PTFE were tightly connected together through the fluorosilane. The surface of the prepared coating had micro-nano secondary structure and had large roughness, which could delay icing and corrosion.

[0183] 10. Silanization treatment

[0184] The prepared composite coating was immersed in the fluorosilane treatment solution for 6 h, dried at 120 °C for 60 min, and cooled to room temperature. The surface energy of the composite coating was reduced, and the anti-icing and corrosion resistance of the coating were further ensured and optimized.

[0185] The foregoing description of specific exemplary embodiments of the application is intended to be illustrative only and is not intended to limit the application to the precise forms described. Many modifications and variations are possible in light of the above teachings without departing from the spirit or essential characteristics of the application. The exemplary embodiments were chosen and described in order to explain the principles of the application and its practical application and to allow others skilled in the art to understand the application for various exemplary embodiments with various modifications being suited to the particular use contemplated. The scope of the application is intended to be defined by the claims and their equivalents.

Claims

1. A fairing having a hydrophobic structure, characterized by, The fairing is in a conical structure, and a side conical surface of the fairing extends a plurality of umbrella-shaped surfaces downward from a conical tip, and an outer surface of each umbrella-shaped surface is provided with a textured pattern and / or an anti-icing and corrosion-resistant coating. The textured pattern includes a boss texture and a groove texture, the boss texture is arranged at a top of the umbrella-shaped surface formed by the conical tip, and the groove texture is arranged at a bottom of the umbrella-shaped surface formed by the conical tip and an outer surface of other umbrella-shaped surfaces. The anti-icing and corrosion-resistant coating sequentially includes, along an adhesion surface from inside to outside, a PTFE coating chemically modified by a sodium naphthalene treatment solution and a GO / PPS composite coating chemically modified by a fluoroalkylsilane treatment solution.

2. The fairing with the hydrophobic structure according to claim 1, wherein The fluoroalkylsilane treatment solution includes one or more of perfluoroalkyl quaternary trimethoxysilane, perfluorodecyl triethoxysilane, perfluorooctyl triethoxysilane, perfluorooctyl trichlorosilane, dodecafluoroheptyl propyl trimethoxysilane, nonafluoroalkyl trimethoxysilane, nonafluoroalkyl triethoxysilane, trifluoroalkyl propyl trimethoxysilane, and trifluoroalkyl triethoxysilane.

3. A method of preparing an icephobic, corrosion resistant coating on the surface of a fairing as defined in claim 1, characterized in that, The method comprises the following steps: (1) material preparation: preparing a fairing substrate, preparing a coating A by dispersing polytetrafluoroethylene emulsion in anhydrous ethanol, and preparing a coating B by dispersing polyphenylene sulfide and graphene oxide in fluoroalkylsilane; (2) preparing a PTFE coating: uniformly spraying the coating A on the surface of the fairing substrate, drying, curing, and cooling to room temperature; (3) sodium naphthalene treatment: preparing a mixed solution by dispersing a sodium naphthalene treatment solution in tetrahydrofuran, immersing the coating prepared in step (2) in the prepared mixed solution, drying, cooling to room temperature, and storing in the dark; (4) preparing a GO / PPS composite coating: uniformly spraying the coating B on the surface of the coating obtained in step (3), drying, curing, and cooling to room temperature; (5) fluoroalkylsilane treatment: immersing the GO / PPS composite coating prepared in step (4) in a fluoroalkylsilane treatment solution, drying, and cooling to room temperature.

4. The method of claim 3, wherein the anti-icing, corrosion resistant coating is prepared by, In step (1), the mass fraction of graphene oxide in the coating B is 5-15%, and the mass fraction of fluoroalkylsilane is 3-5%.

5. The method for preparing the anti-icing and corrosion-resistant coating according to claim 3, wherein In steps (2) and (4), the curing conditions are as follows: increasing the temperature to 320-380°C at a rate of 7-8°C / min, and isothermally sintering for 20-40 min.

6. The method for preparing the anti-icing and corrosion-resistant coating according to claim 3, wherein The PTFE coating prepared in step (2) has a thickness of 30-40 μm. The GO / PPS composite coating prepared in step (4) has a thickness of 200-220 μm.

7. The method for preparing the anti-icing and corrosion-resistant coating according to claim 3, wherein In step (3), the coating prepared in step (2) is immersed for 20-30 s. In step (5), the GO / PPS composite coating prepared in step (4) is immersed for 4-6 h.

8. Application of the fairing with the hydrophobic structure according to any one of claims 1-2 in the field of aircraft ice prevention.

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