Structural, transparent, deicing, and heating coating

Abstract

The application discloses a structure wave-transparent deicing and heating coating and relates to the technical field of aviation. The structure wave-transparent deicing and heating coating comprises a switching element and two heating sheets. The heating sheet comprises a rigid substrate and a plurality of basic units arranged in an array on one side of the rigid substrate. The basic units on the two heating sheets are arranged staggeredly. The basic unit comprises a conductive layer and a heating layer. The conductive layer covers the end of the heating layer. The switching element can make the two heating sheets close to or away from each other. When the two heating sheets are close to each other, the conductive layers on the two rigid substrates can be in contact. The application combines the functions of low detectability and deicing.

Description

Technical Field

[0001] This invention relates to the field of aerospace technology, specifically to a structurally transparent anti-icing and heating coating. Background Technology

[0002] Next-generation aircraft need to possess both low detectability (stealth performance) and anti-icing capabilities. Stealth aircraft require extremely low radar cross-sections (RCS) to evade radar detection, necessitating the use of impedance-matched, high-electrical-loss, or high-magnetic-loss absorbing materials or structures on the aircraft surface to absorb detection electromagnetic waves. Icing is the phenomenon of water condensing into ice on the aircraft's fuselage surface during flight. Aircraft icing can occur on wings, tail fins, engine air intake leading edges, windshields, and instrument sensor heads, often causing flight accidents. Therefore, aircraft anti-icing capability has become a crucial indicator of an aircraft's all-weather flight performance.

[0003] Existing electrothermal films compatible with stealth anti-icing transmit electromagnetic waves by altering the material's conductivity and thickness, with or without patterning to further enhance wave transmission. Even so, there's still a limitation: as wave transmission increases, the heating power for de-icing cannot keep up, resulting in incomplete de-icing.

[0004] Traditional de-icing methods, such as spraying antifreeze, require frequent maintenance, and the antifreeze on the surface can affect the radar absorption effect of the aircraft's stealth honeycomb structure. Hot air de-icing methods reach temperatures as high as 200-300°C, but the radar-absorbing coatings and structures are mostly made of composite materials, making them unable to withstand such high temperatures. Electric heating methods use metal wire heating films, whose strong reflection of electromagnetic waves significantly impacts stealth performance. Superhydrophobic passive de-icing methods are unsuitable for high-speed flight conditions and often lack hydrophobicity. Therefore, current de-icing methods are unsuitable for the surfaces of stealth aircraft.

[0005] Terminology Explanation:

[0006] Stealth fighters: Stealth aircraft require extremely low radar cross section (RCS) to evade radar detection, requiring the aircraft surface to have impedance matching, high electrical loss or high magnetic loss absorbing materials or absorbing structures to absorb detection electromagnetic waves.

[0007] Anti-icing and de-icing: Icing is the phenomenon of water condensing into ice on the surface of an aircraft during flight. Aircraft icing can occur on the wings, tail, leading edge of the engine air intake, windshield, and instrument sensor heads, often causing flight accidents. Aircraft anti-icing capability has become an important indicator for measuring the all-weather flight performance of an aircraft. Summary of the Invention

[0008] The purpose of this invention is to provide a structurally transparent anti-icing heating coating to solve the problems existing in the prior art, and to combine low detectability and anti-icing functions.

[0009] To achieve the above objectives, the present invention provides the following solution:

[0010] This invention provides a structurally transparent anti-icing and de-icing heating coating, comprising an on / off element and two heating elements. Each heating element includes a rigid substrate and a plurality of basic units arranged in an array on one side of the rigid substrate. The basic units on the two heating elements are staggered. Each basic unit includes a conductive layer and a heating layer. The conductive layer covers the end of the heating layer. The on / off element enables the two heating elements to be brought together or moved apart. When the two heating elements are brought together, the conductive layers on the two rigid substrates can contact each other.

[0011] Preferably, the heating layer includes a middle portion and four extension portions. The cross-section of the middle portion is cross-shaped, and the cross-section of the extension portions is rectangular. The four extension portions are located at the four ends of the middle portion. Each heating layer has four conductive layers, and one conductive layer is attached to each extension portion.

[0012] Preferably, the heating layer has a cross-sectional length of w, the extension has a cross-sectional length of a and a width of b, and the heating layer has a thickness of h1; the conductive layer has a cross-sectional length of a, a width of b, and a thickness of h2.

[0013] Preferably, the basic units in two adjacent columns are staggered, and the horizontal and vertical spacing between two adjacent basic units in different columns is wb.

[0014] Preferably, the two heating layers located opposite each other on different heating plates have a lateral spacing of wb and overlap in the longitudinal direction.

[0015] Preferably, the conductive layer is a conductive metal sheet.

[0016] Preferably, the switching element is two electrically controlled expansion tubes, which are located at the lower end of the lower heating element. When energized, the electrically controlled expansion tubes can expand and push the lower heating element to move closer to the upper heating element. When de-energized, the lower heating element falls and separates from the upper heating element.

[0017] Preferably, the switching element is an air pump, and the two heating elements and the external connection structure form a sealed chamber. One end of the air pump is connected to the sealed chamber. When the air pump draws air, the two heating elements move towards each other. When the air pump supplies air, the two heating elements move away from each other.

[0018] The present invention achieves the following technical effects compared to the prior art:

[0019] This invention provides a structurally transparent anti-icing and heating coating. The heating element comprises a rigid substrate and multiple basic units arranged in an array on one side of the rigid substrate. The basic units on two heating elements are staggered. Each basic unit includes a conductive layer and a heating layer. The rigid substrate supports the heating layer and matches the air impedance. The conductive layer covers the end of the heating layer. A switching element allows the two heating elements to be brought together or separated. The two heating elements are mechanically separated, and each is an independent frequency-selective surface with high wave transmittance. When heating is required, the two heating elements are mechanically connected to achieve heating. In this case, the high wave transmittance is not maintained. When the two heating elements are brought together, the conductive layers on the two rigid substrates can contact. The conductive layer reduces contact resistance and prevents excessive contact resistance from causing excessive overall resistance of the heating elements, resulting in poor heating performance. This invention solves the problem of incompatibility between anti-icing and stealth from a physical perspective by mechanically separating the effects of anti-icing and stealth. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the anti-icing and heating coating with structural wave transmission provided by the present invention;

[0022] Figure 2 yes Figure 1 Top view;

[0023] Figure 3 yes Figure 1 Side view;

[0024] Figure 4 This is a dimensional diagram of the basic unit in this invention;

[0025] Figure 5 This is the transmittance diagram of the present invention under normal incidence of electromagnetic waves in the 2GHz-18GHz range;

[0026] In the diagram: 1-conductive layer, 2-heating layer, 3-rigid substrate. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The purpose of this invention is to provide a structurally transparent anti-icing and de-icing heating coating to solve the technical problem of incompatibility between anti-icing and de-icing and stealth in the prior art.

[0029] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] like Figures 1-4 As shown, this embodiment provides a structurally transparent anti-icing and heating coating, including a switching element and two heating elements. Each heating element includes a rigid substrate 3 and multiple basic units arranged in an array on one side of the rigid substrate 3. The basic units on the two heating elements are staggered. Each basic unit includes a conductive layer 1 and a heating layer 2. The rigid substrate 3 supports the heating layer 2 and matches the air impedance. The conductive layer 1 covers the end of the heating layer 2. The switching element allows the two heating elements to be brought together or moved apart, mechanically separating them. Each element is an independent frequency-selective surface with high wave transmittance. When heating is required, the two heating elements are mechanically connected to achieve heating, but this does not provide high wave transmittance. When the two heating elements are brought together, the conductive layers 1 on the two rigid substrates 3 can contact, reducing contact resistance and preventing excessive contact resistance from causing excessive overall resistance of the heating elements, resulting in poor heating performance. This embodiment solves the incompatibility problem between anti-icing and stealth from a physical perspective by mechanically separating the anti-icing and stealth effects.

[0031] Specifically, the heating layer 2 includes a central portion and four extension portions. The central portion has a cross-shaped cross-section, and the extension portions have rectangular cross-sections. The four extension portions are located at the four ends of the central portion. Each heating layer 2 has four conductive layers 1, with one conductive layer 1 attached to each extension portion. However, the specific structure of the heating layer 2 in this embodiment is not limited to the above limitations. The pattern can be an extension of the cross shape. Theoretically, as long as the resistance is broken when the heating elements are separated and connected when they are connected, and the parameters are optimized, the anti-icing and stealth-compatible effects can be achieved.

[0032] The heating layer 2 has a cross-sectional length of w, an extension with a cross-sectional length of a and a width of b, and a thickness of h1; the conductive layer 1 has a cross-sectional length of a, a width of b, and a thickness of h2, and the distance between the two heating elements is h3.

[0033] The basic units in adjacent columns are staggered, and the horizontal and vertical spacing between two adjacent basic units in different columns is wb. That is, the basic unit is shifted horizontally by wb and then downwards by wb. After arraying, it can be seen that the horizontal spacing between two adjacent basic units in each row is 2*(wb), and the vertical spacing between two adjacent basic units in each column is also 2*(wb).

[0034] The two heating layers 2, located on different heating elements, are spaced wb apart laterally and overlap vertically. From the top view, it can be seen that the second heating element is identical to the first, except that the first heating element has been shifted horizontally by wb.

[0035] Conductive layer 1 is a conductive metal sheet, but it can also be made of metal nanowires, metal materials such as Cu and Ag, conductive silver paste, carbon fiber, conductive polymer, etc. The conductive metal sheet serves to connect the two heating elements; because it is a good conductor, its contact resistance is very low.

[0036] The working principle of this embodiment is to divide the original continuous heating film with high reflectivity into two parts. When separated, the film has high transmittance. When heating is needed, the heating film is connected by mechanical movement. At this time, the transmittance of the heating film is low, but the heating effect can still be achieved. When heating is no longer needed, the heating film is disconnected by mechanical movement.

[0037] The switching element consists of two electrically controlled expansion tubes located at the lower end of the lower heating element. When energized, the expansion tubes expand and push the lower heating element toward the upper heating element. When de-energized, the lower heating element falls and detaches from the upper heating element.

[0038] The switching element is an air pump. Two heating elements and an external connection structure form a sealed chamber. One end of the air pump is connected to the sealed chamber. When the air pump draws air, the two heating elements move towards each other. When the air pump supplies air, the two heating elements move away from each other.

[0039] Application Example 1

[0040] The heating layer 2 used is a carbon nanotube-based polymer heating film, the rigid substrate 3 is an acrylic sheet, and the conductive layer 1 is a Cu foil. The specific parameters are as follows:

[0041] w=2mm, a=0.4mm, b=0.5mm, h1=0.1mm, h2=0.01mm, h3=3mm.

[0042] The synthesis method of the carbon nanotube-based polymer is as follows: First, prepare an isopropanol solution of coupling agent KH550 and adjust the pH value to about 9-10. Heat the modified liquid to 50°C at a speed of 140 r / min on a shaker and hydrolyze it for one hour. Add carbon nanotubes to the coupling solution and continue to hydrolyze the carbon nanotube coupling solution on a shaker for one hour (140 r / min, 50°C). Wash the modified carbon nanotubes with acetone and filter them. Finally, dry them in an oven at 50°C and then heat them at 120°C for two hours to obtain modified carbon nanotube powder. The modified carbon nanotubes are easier to disperse in solution.

[0043] Carbon nanotube powder was uniformly dispersed in a viscous liquid of silicone rubber. Xylene solvent was added to dissolve the silicone rubber and carbon nanotubes to obtain a polymer solution containing dissolved carbon nanotubes. A magnet was added, and the solution was stirred for 1 hour using an electromagnetic stirrer. Then, the nano and micron-sized particles inside were uniformly dispersed using an ultrasonic cleaner for about 1 hour.

[0044] Carbon nanotube-based polymers were uniformly sprayed onto an acrylic film using a spraying technique. Unwanted portions of the polymer were then carved away using a laser engraving machine, leaving the designed shape. A 0.01mm thick layer of Cu was magnetron sputtered onto the cut heating layer 2. The heating element was fabricated using the same procedure. Two heating elements were offset horizontally by a distance wb = 1.5mm and then sealed together with a 3mm gap. An electrically controlled expansion tube was used at the bottom to separate and connect the two heating elements.

[0045] Application Example 2

[0046] The heating layer 2 used is a carbon nanotube-based polymer heating film, the rigid substrate 3 is an epoxy resin sheet, and the conductive layer 1 is metallic silver.

[0047] The synthesis method of this carbon nanotube-based polymer is as follows: First, prepare an isopropanol solution of coupling agent KH550 and adjust the pH value to about 9-10. Heat the modified liquid to 50°C at a speed of 140 r / min on a shaker and hydrolyze it for one hour. Add carbon nanotubes to the coupling solution and continue to hydrolyze the carbon nanotube coupling solution on a shaker for one hour (140 r / min, 50°C). Wash the modified carbon nanotubes with acetone and filter them. Finally, dry them in an oven at 50°C and then heat them at 120°C for two hours to obtain modified carbon nanotube powder. The modified carbon nanotubes are easier to disperse in solution.

[0048] Carbon nanotube powder was uniformly dispersed in a viscous liquid of silicone rubber. Xylene solvent was added to dissolve the silicone rubber and carbon nanotubes to obtain a polymer solution containing dissolved carbon nanotubes. A magnet was added, and the solution was stirred for 1 hour using an electromagnetic stirrer. Then, the nano and micron-sized particles inside were uniformly dispersed using an ultrasonic cleaner for about 1 hour.

[0049] The carbon nanotube-based polymer was uniformly sprayed onto the glass cloth with the above pattern using a spraying technique, with the specific parameters as follows:

[0050] w=2mm, a=0.5mm, b=0.2mm, h1=0.1mm, h2=0.01mm, h3=2mm.

[0051] The bottom is heated to 50℃, and after spraying, it is heated to 250℃ for high-temperature curing for 24 hours. Then, the glass cloth is attached to the epoxy resin board with double-sided tape.

[0052] 0.1 mm of conductive silver paste was inkjet printed at the corresponding position on heating layer 2. The heating element was then fabricated using the same procedure. The two heating elements were staggered horizontally by a distance wb = 1.8 mm, then sealed together with a 3 mm gap. A vacuum-ventilation method was used to separate and connect the two heating elements.

[0053] Using the two application examples described above results in a smaller overall thickness, lower density, wider bandwidth, and higher strength.

[0054] For parameter h1, the range can be 0.001mm-1mm, preferably 0.01mm-0.1mm, and even more preferably 0.1mm; for parameter h2, the range can be 0.001mm-1mm, preferably 0.01mm-0.1mm, and even more preferably 0.1mm; for parameter h3, the range can be 1mm-10mm, preferably 2mm-3mm, and even more preferably 3mm; for parameter w, the range can be 1mm-10mm, preferably 2mm-5mm, and even more preferably 2mm; for parameter a, the range can be 0.2mm-1mm, preferably 0.2mm-0.5mm, and even more preferably 0.4mm; for parameter b, the range can be 0.1mm-1mm, preferably 0.2mm-0.5mm, and even more preferably 0.5mm.

[0055] The matrix types of carbon-based conductive nanofilms include silicone rubber, epoxy resin, styrene-butadiene-styrene block copolymer, and polyurethane; the fillers of carbon-based conductive nanofilms include graphene, conductive carbon black, carbon nanotubes, nano-graphite powder, nano-metal powder, and nano-metal wire; the solvents of carbon-based conductive nanofilms include water, ethanol, toluene, xylene, and acetone.

[0056] The material of the rigid substrate 3 can be one or more of epoxy resin, acrylic sheet, glass, wood, fiberglass cloth, silicone rubber, polyurethane, indium tin oxide, polyimide or polymethyl methacrylate or a polymer thereof.

[0057] Conductive metal sheets can be fabricated using methods such as magnetron sputtering, metal powder spraying, metal displacement reaction coating, photolithography, metal sheet mapping, screen printing, inkjet printing, 3D printing, etc.

[0058] like Figure 5 As shown, the top S-Parameters represent the S-parameters; the right side represents the S21 of the S-parameters, indicating the transmission coefficient; the bottom side is the frequency, in GHz; and the left side is dB, which has a one-to-one correspondence with the decimal values.

[0059] This specification uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A structurally transparent anti-icing and heating coating, characterized in that: The device includes a switching element and two heating elements. Each heating element includes a rigid substrate and a plurality of basic units arranged in an array on one side of the rigid substrate. The basic units on the two heating elements are staggered. Each basic unit includes a conductive layer and a heating layer. The conductive layer covers the end of the heating layer. The switching element enables the two heating elements to be brought together or moved apart. When the two heating elements are brought together, the conductive layers on the two rigid substrates can contact each other. The switching element consists of two electrically controlled expansion tubes, which are located at the lower end of the lower heating element. When energized, the electrically controlled expansion tubes expand and push the lower heating element to move closer to the upper heating element. When de-energized, the lower heating element falls and separates from the upper heating element. or, The switching element is an air pump. The two heating elements and the external connection structure form a sealed chamber. One end of the air pump is connected to the sealed chamber. When the air pump draws air, the two heating elements move towards each other. When the air pump supplies air, the two heating elements move away from each other.

2. The anti-icing and heating coating with structural wave transmission according to claim 1, characterized in that: The heating layer includes a middle part and four extensions. The cross-section of the middle part is cross-shaped, and the cross-section of the extensions is rectangular. The four extensions are located at the four ends of the middle part. There are four conductive layers on each heating layer, and one conductive layer is attached to each extension.

3. The anti-icing and heating coating with structural wave transmission according to claim 2, characterized in that: The heating layer has a cross-sectional length of w, the extension has a cross-sectional length of a and a width of b, and the heating layer has a thickness of h1; the conductive layer has a cross-sectional length of a, a width of b, and a thickness of h2; w ranges from 1mm to 10mm, a ranges from 0.2mm to 1mm, b ranges from 0.1mm to 1mm, h1 ranges from 0.001mm to 1mm, and h2 ranges from 0.001mm to 1mm.

4. The anti-icing and heating coating with structural wave transmission according to claim 3, characterized in that: The basic units in two adjacent columns are staggered, and the horizontal and vertical spacing between two adjacent basic units in different columns is wb.

5. The anti-icing and heating coating with structural wave transmission according to claim 3, characterized in that: Between two heating layers located on different heating plates, the lateral spacing is wb, and the longitudinal spacing is overlapping.

6. The anti-icing and de-icing heating coating with structural wave transmission according to claim 1, characterized in that: The conductive layer is a conductive metal sheet.

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