A flexible patch with both stealth and anti-icing functions and its preparation method

Abstract

The present invention relates to a flexible patch with both stealth and anti-icing functions and a method for preparing it. The flexible patch comprises a substrate, an absorbing coating, an insulating layer, and an electric heating coating. The absorbing coating is disposed on the substrate, and the electric heating coating is disposed on the absorbing coating with an insulating layer disposed between the two coatings. The electric heating coating is a TiN film layer and is connected to a wire for electrical heating. By using the TiN film layer as the electric heating coating, it has strong wave transmission capabilities and adjustable resistance, making it a suitable alternative to currently common electric heating coatings containing nano-conductive fillers. This solves the problem of electromagnetic wave reflection by the electric heating coating, and allows it to be placed above the absorbing coating, reducing the heating power loss associated with placement below the absorbing coating.

Description

Technical Field

[0001] The present invention relates to the field of surface engineering technology, and in particular to a flexible patch having both stealth and anti-icing functions and a preparation method thereof. Background Art

[0002] Aircraft icing usually occurs on concave and convex parts such as the leading edge of the wing, horizontal tail, engine air intake, or parts such as the windshield, instrument sensor head, and helicopter propeller, and will cause great damage to flight performance. For example, wing icing will destroy the aerodynamic performance of the aircraft, increase the aircraft's drag and gravity, and tail icing will also affect the aircraft's maneuverability. These problems will cause the aircraft to lose balance, make takeoff difficult, and even cause air crashes. Most aircraft in service use complex anti-icing systems, such as: (1) heating through resistance wires, etc.; (2) making parts hollow and then passing hot air; (3) pneumatic deicing; (4) electric repulsion. The most widely used is the thermal anti-icing system, which has the following characteristics: (1) heating deicing is an energy-consuming anti-icing method with high anti-icing energy consumption, and the energy consumption of a single machine can even reach hundreds of kilowatts; (2) heating anti-icing methods and other commonly used anti-icing methods usually require additional anti-icing systems. Such systems consume a lot of energy, are complex, have high system reliability requirements, and are heavy and large in size, which restricts the weight reduction of aircraft.

[0003] In recent years, with the rapid development of materials and interface science, new anti-icing methods have continuously emerged. One of the most promising anti-icing methods is the composite anti-icing method of super-hydrophobic coatings and electrothermal coatings. Compared with traditional resistance wire heating anti-icing methods, this method is low-cost, low-energy, and easy to implement. Compared with hot air anti-icing methods, this method does not require hollow parts, reducing design complexity. These two aspects make it an ideal anti-icing method with great potential application value. In particular, given that current air-heating and electrothermal anti-icing methods struggle to meet the low-heat and energy-saving requirements of stealth aircraft and drones, the development of composite anti-icing methods of super-hydrophobic coatings and electrothermal coatings has attracted considerable attention from both domestic and international research partners. Widely used radar-absorbing coatings contain ferromagnetic absorbers. These coatings have a relatively wide bandwidth and excellent absorption performance. Their principle is that the uniformly distributed ferromagnetic particles in the coating interact with electromagnetic waves, converting electromagnetic energy into heat. However, the absorption bandwidth of radar-absorbing coatings is still relatively narrow, and the absorption effect needs to be improved.

[0004] At present, the electric thermal coating in the composite anti-icing method of super-hydrophobic coating and electric thermal composite coating has a reflective effect on radar waves. If the electric thermal coating is placed directly above the stealth coating, although it will maintain a good low-power anti-icing effect, the reflection of the electric thermal coating on radar waves will seriously affect the absorption effect of the absorbing coating; if the electric thermal coating is placed below the stealth coating, it will not only affect the thermal energy transmission of the electric thermal coating, resulting in increased energy consumption, but also affect the electromagnetic properties of the absorber due to the heating effect of the electric thermal coating, resulting in the deterioration of the absorbing effect of the absorbing coating. This leads to the incompatibility of the composite anti-icing method of super-hydrophobic coating and electric thermal coating with radar stealth coating, that is, the contradiction between efficient thermal energy transmission and radar wave absorption. Summary of the Invention

[0005] (1) Technical issues to be solved

[0006] The embodiment of the present invention provides a flexible patch compatible with stealth and anti-icing functions and a preparation method thereof, which solves the technical problem of incompatibility between stealth and anti-icing functions.

[0007] (2) Technical solution

[0008] In the first aspect, an embodiment of the present invention proposes a flexible patch that is compatible with stealth and anti-icing functions, comprising: a substrate, an absorbing coating, an insulating layer, and an electric heating coating, wherein the absorbing coating is arranged on the substrate, the electric heating coating is arranged on the absorbing coating, and an insulating layer is arranged between the electric heating coating and the absorbing coating, the electric heating coating is a TiN film layer, and is connected to a wire for electrical heating.

[0009] Furthermore, a coating primer is provided between the absorbing coating and the substrate, and the coating primer is made of polyurethane resin.

[0010] Furthermore, the absorbing coating includes a medium- and low-frequency absorbing coating and a high-frequency absorbing coating. The medium- and low-frequency absorbing coating is prepared using flaky carbonyl iron and polyurethane materials, and the absorbing agent content is 25% to 35%. The high-frequency absorbing coating is prepared using spherical ferrite and polyurethane materials, and the absorbing agent content is 15% to 20%. The medium- and low-frequency absorbing coating and the high-frequency absorbing coating are bonded to each other, the medium- and low-frequency absorbing coating is the bottom layer, and the high-frequency absorbing coating is the surface layer.

[0011] Furthermore, a moth-eye anti-reflection structure is provided on the absorbing coating. The diameter of the regular hexagonal inscribed circle of the moth-eye anti-reflection structure is 3-4 mm, the line width is 0.1-0.5 mm, and the depth is not less than 80% of the total thickness of the absorbing coating.

[0012] Furthermore, the insulating layer is a polyurethane resin coating.

[0013] Furthermore, a hydrophobic coating is provided on the electric heating coating, and the hydrophobic coating is made of fluorinated silicone resin.

[0014] Furthermore, a hydrophobic structure is provided on the hydrophobic coating, and the hydrophobic structure is a micron and submicron blind hole and / or a micron forward groove and / or a micro-nano stripe structure.

[0015] Furthermore, the processing depth of the hydrophobic structure does not exceed 2 / 3 of the thickness of the hydrophobic coating.

[0016] Furthermore, the thickness of the TiN film layer is 300-450 nm, and the resistivity is 20-100 mΩ·cm.

[0017] In a second aspect, a method for preparing a flexible patch having both stealth and anti-icing functions is provided, comprising the steps of:

[0018] Spraying a coating primer on the surface of the substrate;

[0019] The surface of the coating primer is first sprayed with a medium and low frequency absorbing coating, and then with a high frequency absorbing coating to form an absorbing coating;

[0020] After the high-frequency absorbing coating is dry and before the medium- and low-frequency absorbing coating and the high-frequency absorbing coating are cured, the surface of the absorbing coating is micro-embossed using a mold for making a moth-eye anti-reflection structure. Simultaneously, low-temperature heating is performed to shape the absorbing coating. After shaping, the absorbing coating is demoulded and then cured.

[0021] Spraying an insulating layer on the surface of the absorbing coating, filling the surface of the absorbing coating with the insulating layer, and forming an insulating layer with a flat and smooth surface;

[0022] After the surface of the insulation layer is dry, press the conductors into both ends of the surface of the insulation layer and then perform low-temperature curing;

[0023] The patch was placed in a vacuum chamber and a TiN film was deposited by reactive magnetron sputtering;

[0024] Spraying a hydrophobic coating on the surface of the TiN film and performing low-temperature curing;

[0025] The surface of the hydrophobic coating is scanned by a femtosecond laser to produce a hydrophobic structure.

[0026] (3) Beneficial effects

[0027] In summary, the present invention adopts a TiN film layer as the electric heating coating, which has the characteristics of strong wave transmission ability and adjustable resistance. It can replace the currently common electric heating coating with added nano-conductive fillers (nano-conductive fillers include one or more of graphene, conductive carbon black, carbon nanotubes, nano-graphite powder, nano-metal powder and nano-metal wires), solves the problem of reflection of electromagnetic waves by the electric heating coating, can be arranged on the absorbing coating, and reduces the heating power loss of the electric heating coating caused by being arranged under the absorbing coating. It has the following advantages:

[0028] 1. The absorbing coating adopts a double-layer design with a composite bionic microstructure. The bottom layer is a medium- and low-frequency absorbing layer containing flake carbonyl iron, and the top layer is a high-frequency absorbing layer containing spherical ferrite. The surface adopts a moth-eye anti-reflection structure, which improves the absorption effect of the absorbing coating and broadens the frequency band.

[0029] 2. A hydrophobic coating is provided on the electric heating coating, and a hydrophobic structure is processed to improve the hydrophobic effect;

[0030] 3. The flexible patch, made by applying multiple coatings to the substrate, can be glued to any part of the aircraft, ensuring the easy implementation and low energy consumption of the anti-icing function, while also achieving broadband and efficient absorption of radar waves. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0032] Figure 1 This is a structural diagram of a flexible patch that is compatible with stealth and anti-icing functions;

[0033] Figure 2 This is the SEM image of the moth-eye anti-reflection structure;

[0034] Figure 3 This is an SEM image of the hydrophobic coating with micron and submicron blind holes;

[0035] Figure 4 This is an SEM image of the hydrophobic coating with micron-scale forward grooves;

[0036] Figure 5 This is an SEM image of the hydrophobic coating with a micro-nanoscale stripe structure;

[0037] Figure 6 It is a radar wave reflection loss curve of a flexible patch with both stealth and anti-icing functions and different forms of absorbing coatings;

[0038] Figure 7 This is a schematic diagram of the structure of a mold for making a moth-eye anti-reflection structure;

[0039] In the figure: 1. Substrate; 2. Coating primer; 3. Absorbing coating; 4. Moth-eye anti-reflection structure; 5. Insulation layer; 6. Wire; 7. Electric heating coating; 8. Hydrophobic coating; 9. Hydrophobic structure. DETAILED DESCRIPTION

[0040] The following detailed description of the embodiments of the present invention is provided in conjunction with the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are intended to illustrate the principles of the present invention and are not intended to limit the scope of the present invention. That is, the present invention is not limited to the described embodiments and covers any modifications, replacements, and improvements to the parts, components, and connection methods without departing from the spirit of the present invention.

[0041] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0042] Please refer to Figure 1 An embodiment of the present invention proposes a flexible patch with both stealth and anti-icing functions, comprising: a substrate 1, an absorbing coating 3, an insulating layer 5, and an electric heating coating 7. The absorbing coating 3 is disposed on the substrate 1, which may be flexible. The electric heating coating 7 is disposed on the absorbing coating 3, with the insulating layer 5 disposed between the absorbing coating 7 and the absorbing coating 3. The electric heating coating 7 is a TiN film layer and is connected to a wire 6 for electrical heating. The TiN film layer as the electric heating coating 7 has the characteristics of strong wave transmission and adjustable resistance. It can replace the currently common electric heating coating 7 with nano-conductive fillers (nano-conductive fillers include one or more of graphene, conductive carbon black, carbon nanotubes, nano-graphite powder, nano-metal powder, and nano-metal wire). This solves the problem of electromagnetic wave reflection by the electric heating coating. The TiN film layer can be disposed above the absorbing coating 3, reducing the heating power loss of the electric heating coating 7 caused by its placement below the absorbing coating 3. At the same time, the flexible patch made by applying multiple coatings to the substrate 1 can be glued to any part of the aircraft, ensuring the easy implementation and low energy consumption of the anti-icing function, and also achieving broadband and efficient absorption of radar waves.

[0043] In some embodiments, a coating primer 2 is provided between the absorbing coating 3 and the substrate 1 . The coating primer 2 is made of polyurethane resin and is used to increase the bonding strength between the absorbing coating 3 and the substrate 1 .

[0044] In some embodiments, the absorbing coating 3 includes a medium- and low-frequency absorbing coating and a high-frequency absorbing coating. The medium- and low-frequency absorbing coating is prepared using flaky carbonyl iron and polyurethane materials, and the absorbing agent content is 25% to 35%. The high-frequency absorbing coating is prepared using spherical ferrite and polyurethane materials, and the absorbing agent content is 15% to 20%, so that the absorbing coating 3 has good absorbing performance.

[0045] Please refer to Figure 2 In some embodiments, a moth-eye anti-reflection structure 4 is provided on the absorbing coating 3. The diameter of the regular hexagonal inscribed circle of the moth-eye anti-reflection structure 4 is 3 to 4 mm, the line width is 0.1 to 0.5 mm, and the depth is not less than 80% of the total thickness of the absorbing coating 3. The moth-eye anti-reflection structure 4 is used to generate electromagnetic wave diffraction and resonance, adjust the impedance matching of the absorbing coating 3, thereby expanding the absorbing frequency band and improving the absorbing effect.

[0046] In some embodiments, the insulating layer 5 is a polyurethane resin coating, which has good insulating properties and is easy to spray.

[0047] In some embodiments, a hydrophobic coating 8 is provided on the electric heating coating 7. The hydrophobic coating 8 is made of fluorinated silicone resin and has good hydrophobicity.

[0048] Please refer to Figures 3 to 5 In some embodiments, a hydrophobic structure 9 is provided on the hydrophobic coating 8. The hydrophobic structure 9 is a micron and submicron blind hole and / or micron forward groove and / or micro-nano stripe structure. When the electric heating coating 7 is heated, a water film can be formed on the surface to promote the shedding of the ice layer, thereby further reducing the de-icing power consumption.

[0049] In some embodiments, the processing depth of the hydrophobic structure 9 does not exceed 2 / 3 of the thickness of the hydrophobic coating 8. Since the ultrafast laser will induce a nanostructure when processing the resin coating microstructure, the fluorinated silicone hydrophobic coating 8 will have excellent superhydrophobic function under the action of the micro-nano secondary structure.

[0050] In some embodiments, the TiN film layer has a thickness of 300-450 nm and a resistivity of 20-100 mΩ·cm, and has a good thermal conversion rate.

[0051] In a second aspect, a method for preparing a flexible patch having both stealth and anti-icing functions is provided, comprising the steps of:

[0052] 1. Spraying polyurethane resin on the surface of the flexible substrate 1 using a pneumatic spray gun (the following spraying methods can all be sprayed using a pneumatic spray gun) to form a coating primer 2 to enhance the bonding strength of the radar absorbing coating 3;

[0053] 2. First spray a medium- and low-frequency absorbing coating on the surface of the coating primer 2, and then spray a high-frequency absorbing coating to form an absorbing coating 3;

[0054] 3. After the high-frequency absorbing coating is dry, and before the medium- and low-frequency absorbing coating and the high-frequency absorbing coating are cured, a mold for making the moth-eye anti-reflection structure 4 is used (see Figure 7 ) performing micro-embossing on the surface of the absorbing coating 3 and simultaneously heating at a low temperature to shape the absorbing coating 3, demolding after shaping, and then curing the absorbing coating 3;

[0055] 4. Spraying an insulating layer 5 on the surface of the absorbing coating 3 to fill the surface of the absorbing coating 3 with the insulating layer 5 and form an insulating layer 5 with a flat and smooth surface;

[0056] 5. After the surface of the insulating layer 5 is dry, the conductors 6 are pressed into both ends of the surface of the insulating layer 5 and then cured at low temperature;

[0057] 6. Place the patch in a vacuum chamber and deposit a TiN film by reactive magnetron sputtering;

[0058] 7. Spray a hydrophobic coating 8 on the surface of the TiN film and perform low-temperature curing;

[0059] 8. The surface of the hydrophobic coating 8 is scanned by a femtosecond laser to form a hydrophobic structure 9.

[0060] Example 1:

[0061] 1. PET film was selected as the flexible substrate 1. After diluting the polyurethane resin, it was evenly sprayed on the substrate 1 using a pneumatic spray gun to form a coating primer 2 with a thickness of 0.1 mm.

[0062] 2. After the primer has dried, a coating consisting of flaky carbonyl iron absorbers, polyurethane resin, and butyl acetate diluent is formulated with an absorber content of 30%. This coating is evenly sprayed using a pneumatic spray gun to form a low- and medium-frequency absorbing coating with a thickness of approximately 0.7 mm, serving as the bottom layer of absorbing coating 3. A coating consisting of spherical ferrite absorbers, polyurethane resin, and butyl acetate diluent is formulated with an absorber content of 15% to 20%. After the bottom layer has dried, this coating is evenly sprayed using a pneumatic spray gun to form a high-frequency absorbing coating with a thickness of approximately 0.3 mm, serving as the top layer of absorbing coating 3.

[0063] 3. After the surface of the absorbing coating 3 is dry, but before the two layers of absorbing coating 3 are cured, a pre-processed mold for the moth-eye anti-reflection structure 4 (using ultrafast laser or precision machining to create close-packed regular hexagonal pits with an inscribed circle diameter of 4 mm, a line width of 0.2 mm, and a pit depth of 1.1 mm) is used to micro-emboss the absorbing coating 3. Simultaneously, the mold is heated and dried at 60°C to promote the setting of the absorbing coating 3. The mold is then removed, and the absorbing coating 3 is cured at 120°C.

[0064] 4. Use a pneumatic spray gun to evenly spray the diluted polyurethane solution onto the surface of the absorbing coating 3, filling the regular hexagonal gaps on the surface to form a flat and smooth coating, which serves as the insulating layer 5 between the electric heating coating and the absorbing coating 3;

[0065] 5. After the insulation layer 5 is dry, press silver wires 6 with a width of 4 mm into both ends of the patch and then cure at 120°C;

[0066] 6. Place the flexible patch in a vacuum chamber, evacuate to 4×10-3Pa, introduce argon gas at a flow rate of 150sccm, turn on the gas ion source, use a -50V bias, perform plasma cleaning for 5 minutes to activate the surface, then turn off the bias, adjust the argon flow rate to 100sccm, introduce nitrogen at a flow rate of 30sccm, control the pressure in the vacuum chamber at about 0.9Pa, turn on the Ti magnetron sputtering target at a power of 100W, and perform reactive magnetron sputtering to deposit a TiN film for 20 minutes, so that the film thickness is about 350nm and the resistivity is about 35mΩ·cm;

[0067] 7. Dilute the fluorinated silicone resin with n-hexane to form an easy-to-spray solution, then evenly spray it on the flexible patch using a pneumatic spray gun to form a smooth, flat, hydrophobic coating 8 with a thickness of 0.3 mm. Curing is performed at 120°C.

[0068] 8. A femtosecond laser was used to scan the surface of the hydrophobic coating 8 and process micron-scale blind hole microstructures. The femtosecond laser pulse width was 300 fs, the wavelength was 515 nm, the output frequency was 200 kHz, and the average power was 14 W. The aperture size was controlled by changing the single pulse energy, and the spacing was controlled by setting the filling spacing P, where P = P1-d (P1 is the actual spacing, and d is the energy processing diameter). The depth was determined by controlling the number of processing times N. Therefore, the single pulse energy was set to 0.007 mJ, the filling spacing was set to 0.5 μm, and the scanning speed was set to 200 m / s.

[0069] It should be noted that the various embodiments in this specification are described in a progressive manner. References to the same or similar parts between the various embodiments are sufficient. Each embodiment focuses on the differences from the other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. Furthermore, for the sake of brevity, detailed descriptions of known methods and technologies are omitted here.

[0070] The foregoing is merely an embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art without departing from the scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included within the scope of the claims of the present application.

Claims

1. A flexible patch with both stealth and anti-icing functions, characterized in that: include: A substrate, an absorbing coating, an insulating layer, and an electric heating coating, wherein the absorbing coating is disposed on the substrate, the electric heating coating is disposed on the absorbing coating, and an insulating layer is disposed between the electric heating coating and the absorbing coating. The electric heating coating is a TiN film layer and is connected to a wire for electrically heating. A moth-eye anti-reflection structure is disposed on the absorbing coating, wherein the diameter of the regular hexagonal inscribed circle of the moth-eye anti-reflection structure is 3 to 4 mm, the line width is 0.1 to 0.5 mm, and the depth is not less than 80% of the total thickness of the absorbing coating. A hydrophobic coating is disposed on the electric heating coating, wherein the hydrophobic coating uses a fluorinated silicone resin, and a hydrophobic structure is disposed on the hydrophobic coating, wherein the hydrophobic structure is a micron and submicron blind hole and / or a micron-level forward groove and / or a micro-nanoscale stripe structure.

2. The flexible patch with both stealth and anti-icing functions according to claim 1, characterized in that: A coating primer is provided between the absorbing coating and the substrate, and the coating primer is made of polyurethane resin.

3. The flexible patch with both stealth and anti-icing functions according to claim 1, characterized in that: The absorbing coating includes a medium- and low-frequency absorbing coating and a high-frequency absorbing coating. The medium- and low-frequency absorbing coating is prepared using flaky carbonyl iron and polyurethane materials, and the absorbing agent content is 25% to 35%. The high-frequency absorbing coating is prepared using spherical ferrite and polyurethane materials, and the absorbing agent content is 15% to 20%. The medium- and low-frequency absorbing coating and the high-frequency absorbing coating are bonded to each other, with the medium- and low-frequency absorbing coating serving as the bottom layer and the high-frequency absorbing coating serving as the surface layer.

4. The flexible patch with both stealth and anti-icing functions according to claim 1, characterized in that: The insulating layer is a polyurethane resin coating.

5. The flexible patch with both stealth and anti-icing functions according to claim 1, characterized in that: The processing depth of the hydrophobic structure does not exceed 2 / 3 of the thickness of the hydrophobic coating.

6. The flexible patch with both stealth and anti-icing functions according to claim 1, characterized in that: The thickness of the TiN film layer is 300-450 nm, and the resistivity is 20-100 mΩ·cm.

7. A method for preparing a flexible patch with both stealth and anti-icing functions, characterized in that: Including steps: Spraying a coating primer on the surface of the substrate; The surface of the coating primer is first sprayed with a medium and low frequency absorbing coating, and then with a high frequency absorbing coating to form an absorbing coating; After the high-frequency absorbing coating is dry and before the medium- and low-frequency absorbing coating and the high-frequency absorbing coating are cured, the surface of the absorbing coating is micro-embossed using a mold for making a moth-eye anti-reflection structure. Simultaneously, low-temperature heating is performed to shape the absorbing coating. After shaping, the absorbing coating is demoulded and then cured. Spraying an insulating layer on the surface of the absorbing coating, filling the surface of the absorbing coating with the insulating layer, and forming an insulating layer with a flat and smooth surface; After the surface of the insulation layer is dry, press the conductors into both ends of the surface of the insulation layer and then perform low-temperature curing; The patch was placed in a vacuum chamber and a TiN film was deposited by reactive magnetron sputtering; Spraying a hydrophobic coating on the surface of the TiN film and performing low-temperature curing; The surface of the hydrophobic coating is scanned by a femtosecond laser to produce a hydrophobic structure.

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