Composite material heating structure and preparation method thereof

Abstract

The invention belongs to the field of composite material preparation, and relates to a composite material heating structure and a preparation method thereof. Based on the porous structure characteristic and the excellent electric heating characteristic of the carbon nanotube film, the carbon nanotube film and the glass fiber prepreg are stacked and laid, and curing connection of the carbon nanotube film and the prepreg is achieved under the pressure condition through external drying oven heating or internal self-resistance heating. The prepared composite board can be placed on the surface of a component and can also be embedded into the component in a hot press molding mode, and therefore the electric heating anti-icing and deicing functions of the composite component are achieved. The method is high in flexibility degree, can be used for single-piece or small-batch production, and can also be used for large-batch production.

Description

Technical Field

[0001] The invention belongs to the field of composite material preparation, and relates to a composite material heating structure and a preparation method thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Fiber-reinforced resin-based composite materials inherit the excellent physical and chemical properties of fibers and have been widely used in the aerospace field, especially in aircraft manufacturing. They are used to manufacture load-bearing structures such as vertical tails, horizontal tails, wings and fuselages. During the operation of an aircraft, ice formation on key parts is a common physical phenomenon, which can lead to increased aircraft resistance, decreased aircraft balance, and center of gravity shift. It is one of the important causes of aircraft accidents. In response to such problems, surface anti-icing technology for fiber-reinforced resin-based composite materials has emerged. The electrothermal anti-icing technology generates Joule heat through heating elements to make the surface temperature of the composite material reach above the freezing point, thereby destroying the ice layer or preventing ice formation. This technology has the advantages of high electrothermal conversion efficiency, simple control, and no damage to the deicing surface. It has become an effective method to solve the problem of icing on the surface of aircraft.

[0004] At present, a mainstream anti-icing heating technology for composite components is to use carbon nanotube film as a heating element, and to coat prepreg on the upper and lower sides of the carbon nanotube film and heat and solidify it to form a fiber / carbon nanotube film composite plate. The advantages of using carbon nanotube film as a heating element are: the pure carbon component and self-supporting structure of the carbon nanotube film make it have excellent resistance to high and low temperatures and acid and alkali environments; surface heating has a larger normal heat dissipation area than traditional resistance wire heating, and its heating efficiency and heat utilization efficiency are significantly improved compared to filamentary or rod-shaped heating bodies, which can evenly heat the surface of composite components. However, in actual applications, due to functional requirements such as rivet connections and instrument buttons, holes often appear inside the heating body. A single hole may have a negative impact on the overall surface heating uniformity, resulting in local overheating, thereby affecting the overall heating effect, and even causing local failure of the resin-based composite material. Summary of the invention

[0005] The purpose of the present invention is to address the problems of poor uniformity of actual planar heating, local temperature concentration, and inability to accurately control resistance values ​​in existing anti-icing heating technologies, and propose a method for preparing a resin-based composite material component based on a carbon nanotube film grid structure. The prepared composite plate can be placed on the surface of the component or embedded in the component by hot pressing, thereby realizing the electric heating anti-icing function of the composite material component. The method has a high degree of flexibility and can be used for single-piece or small-batch production, as well as for mass production.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A first aspect of the present invention provides a method for preparing a composite material heating structure, comprising:

[0008] The gridded carbon nanotube film and the prepreg are stacked and laid, and the carbon nanotube film and the prepreg are cured and formed by external heating or internal self-resistance heating under pressure conditions.

[0009] In some embodiments, two sides of the gridded carbon nanotube film are electrically connected to copper foil electrodes.

[0010] In some embodiments, the long side of the copper foil is aligned with the wide side of the carbon nanotube film.

[0011] The shape of the grid will affect the overall conductivity of the carbon nanotube film. Research and development found that the circular, elliptical and triangular shapes have no obvious effect on improving the overall conductivity of the carbon nanotube film. Therefore, in some embodiments, the shape of the grid is selected from square, hexagon or rhombus to significantly improve the overall conductivity of the carbon nanotube film.

[0012] Preferably, the grid spacing is 5-15 mm, and the grid side length is 6-10 mm.

[0013] In some embodiments, the carbon nanotube film is disposed on a surface layer or an intermediate layer of a component.

[0014] In some embodiments, the curing and forming method is a vacuum bag method, an autoclave method, or a carbon nanotube film self-resistance heating curing method.

[0015] In some embodiments, the prepreg is a glass fiber reinforced phenolic resin.

[0016] In some embodiments, the curing temperature is 180° C., and the heat preservation and pressure holding time is 180 min.

[0017] The second aspect of the present invention provides a composite material heating structure prepared by the above method.

[0018] The third aspect of the present invention provides application of the above-mentioned composite material heating structure in aircraft manufacturing.

[0019] Beneficial effects of the present invention

[0020] (1) The present invention proposes a method of embedding a gridded carbon nanotube film into a resin composite material layer and hot pressing it together with other fiber prepregs to form an electric heating composite material component with an anti-deicing function; this method and structure can avoid the negative impact of holes in the heating body due to rivet connections, instrument buttons and other functional requirements on the overall surface heating uniformity;

[0021] (2) The gridding process of the present invention can improve the overall resistance of the carbon nanotube film electric heating element, and can solve the technical problems of low surface resistance, poor designability and insufficient applicability of traditional carbon nanotube films;

[0022] (3) The present invention utilizes the electrothermal properties of carbon nanotube films to achieve the electrothermal anti-icing function of composite material components, so that it can provide a new solution for applications in electric vehicle battery thermal management, aircraft local anti-icing, spacecraft thermal protection, etc. In addition, due to the porous structure characteristics of the carbon nanotube film, it can form a co-cured structure with the resin without reducing the structural mechanical properties of the component. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention, and the exemplary embodiments of the present invention and their description are used to explain the present invention and do not constitute improper limitations on the present invention.

[0024] Figure 1 : Overall flow chart;

[0025] Figure 2 :(a) Physical picture of gridded carbon nanotube film;(b) Electrothermal effect picture of gridded carbon nanotube film;(c) Electrothermal effect picture of film without gridding treatment;

[0026] Figure 3 : Schematic diagram of the three-dimensional structure of the composite material embedded with gridded carbon nanotube film;

[0027] Figure 4 : Schematic diagram: (a) vacuum bag method; (b) autoclave method; (c) carbon nanotube film self-resistance heating curing method;

[0028] Figure 5 : Composite material board: (a) actual picture; (b) electric heating effect picture. DETAILED DESCRIPTION

[0029] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0030] The present invention will be further described in detail below in conjunction with specific embodiments. It should be noted that the specific embodiments are intended to explain the present invention rather than to limit it.

[0031] Example 1

[0032] The overall flow chart is as follows Figure 1 shown.

[0033] (1) A carbon nanotube film with a square resistance of 0.5-10Ω / □ prepared by a floating catalytic chemical vapor deposition method is selected, and a cotton cloth soaked in alcohol is used to wipe it along its orientation direction. After wiping, it is naturally dried in the air.

[0034] (2) Cutting the carbon nanotube film into grids can be done by laser cutting or cutting with a knife. The specific grid shape can be square, hexagonal, diamond, etc. In the present invention, a square grid structure is used.

[0035] (3) Bond the copper foil electrodes to both sides of the carbon nanotube film, so that the copper foil and the carbon nanotube film are electrically connected, and the long side of the copper foil is aligned with the wide side of the carbon nanotube film. The actual image of the obtained gridded carbon nanotube film and its electrothermal effect are shown in Figures 1 and 2. Figure 2 As shown in (a) and (b), the electrothermal images of the thin film without gridding are as follows: Figure 2 As shown in (c), it can be seen that the temperature is more uniform after gridding processing.

[0036] (4) Lay the grid heating unit and the composite prepreg in layers. The grid heating unit can be placed on the surface or middle layer of the component. The structural diagram is shown in FIG. Figure 3 Shown

[0037] (5) The prepreg and the carbon nanotube film are attached to the isolation film (i.e., isolation films are arranged on the upper and lower surfaces of all the layers, and no isolation film is arranged between each layer). The specific order of the layers depends on the situation. Figure 3 Just a case of ply.

[0038] (6) After the layers are attached, completely wrap the mold and layers with a clean release film.

[0039] (7) The above composite material structure can be cured and formed in three ways:

[0040] A: Vacuum bag method: Place the above structure in a vacuum bag, seal the bag on all sides, evacuate the bag through the vacuum hole, and place the bag in an oven for heating and curing. The specific curing process depends on the type of resin.

[0041] B: Autoclave method: Place the above structure in a vacuum bag. After the vacuum bag is sealed on all sides, evacuate the bag through the vacuum hole to a vacuum pressure of 0.1MPa. Place the vacuum bag as a whole in an autoclave. Replace the air in the autoclave with nitrogen, argon or other protective gases, and inflate the air to a pressure of more than 0.5MPa. Set different temperature curves according to different resin types to cure the overall structure of the composite material.

[0042] C: Carbon nanotube film self-resistance heating curing method: Place the above structure in a vacuum bag, seal the bag on all sides, and extend the copper foil electrode out of the vacuum bag for electrical heating. Evacuate the bag through the vacuum hole, and the vacuum pressure is 0.1MPa; place the composite structure wrapped in the vacuum bag in a pressure tank, and apply pressure by inflating the inside; connect the copper foil electrode of the grid heating element to the outside of the pressure tank through a wire through the sealed port, and connect it to a power source, and heat the entire structure to the curing temperature after power is turned on.

[0043] The schematic diagrams of the above three methods are as follows: Figure 4 As shown in (a), (b) and (c).

[0044] (8) The actual picture of the composite material plate obtained by the above method and its electrothermal effect picture are as follows: Figure 5 As shown in (a) and (b), the selected prepreg is glass fiber reinforced phenolic resin, the curing temperature is 180°C, and the heat preservation and pressure holding time is 180 minutes.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a composite material heating structure, characterized in that: include: The gridded carbon nanotube film and the prepreg are stacked and laid, and under pressure conditions, external heating or internal self-resistance heating is used to solidify the carbon nanotube film and the prepreg to obtain the product.

2. The method for preparing a composite material heating structure according to claim 1, characterized in that: Both sides of the gridded carbon nanotube film are electrically connected to the copper foil electrodes.

3. The method for preparing a composite material heating structure according to claim 2, characterized in that: The long side of the copper foil is aligned with the wide side of the carbon nanotube film.

4. The method for preparing a composite material heating structure according to claim 1, characterized in that: The shape of the grid is selected from square, hexagon or rhombus; Or, the grid spacing is 5-15 mm, and the grid side length is 6-10 mm.

5. The method for preparing a composite material heating structure according to claim 1, characterized in that: The carbon nanotube film is placed on the surface layer or the middle layer of the component.

6. The method for preparing a composite material heating structure according to claim 1, characterized in that: The curing and forming method is a vacuum bag method, a hot press method or a carbon nanotube film self-resistance heating curing method.

7. The method for preparing a composite material heating structure according to claim 1, characterized in that: The prepreg is glass fiber reinforced phenolic resin.

8. The method for preparing a composite material heating structure according to claim 1, characterized in that: The curing temperature is 180°C and the heat preservation and pressure holding time is 180 minutes.

9. A composite heating structure prepared by the method according to any one of claims 1 to 8.

10. Use of the composite material heating structure according to claim 9 in aircraft manufacturing.

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