A flexible corrosion-resistant carbon nanotube electromagnetic shielding film and a preparation method thereof

Abstract

The application discloses a flexible corrosion-resistant carbon nanotube electromagnetic shielding film and a preparation method thereof, and relates to the technical field of electromagnetic shielding. The carbon nanotube electromagnetic shielding film comprises a crystalline carbon nanotube film and amorphous pyrolytic carbon loaded on the surface and inside of the crystalline carbon nanotube film; and the carbon nanotubes in the crystalline carbon nanotube film are mutually overlapped to form a three-dimensional network structure. After the amorphous pyrolytic carbon is deposited on the surface of the original carbon nanotube film, the corrosion is prevented from extending inward, so that the overall corrosion resistance of the film is enhanced.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic shielding technology, specifically to a flexible, corrosion-resistant carbon nanotube electromagnetic shielding film and its preparation method. Background Technology

[0002] In recent years, the development of portable electronic devices and wireless communication technologies has brought convenience but also caused serious electromagnetic interference. Harmful electromagnetic interference can not only lead to temporary or permanent malfunctions of electronic systems but also harm the surrounding environment and human health. Therefore, developing efficient shielding materials has become an important means to reduce electromagnetic interference and solve electromagnetic problems, and is a key research area in materials science.

[0003] Besides high shielding performance, excellent shielding materials should also be ultra-lightweight, ultra-thin, high-strength, and flexible, especially for use in aircraft, spacecraft, drones, portable devices, and wearable electronics. Currently, most commercially available electromagnetic shielding materials are metallic materials with high electrical conductivity. However, metallic materials suffer from poor flexibility, poor corrosion resistance, and high density. Carbon nanotubes (CNTs) have attracted widespread attention due to their unique properties, such as excellent electrical conductivity, tensile strength, high toughness, and low density. CNT-based electromagnetic shielding films and their composites have been widely used in the electromagnetic shielding field. For example, CNT materials doped with highly conductive components can achieve higher electromagnetic shielding effectiveness than single-component materials. However, because CNTs themselves cannot withstand corrosion from certain strong protic acids, such as chlorosulfonic acid (CSA) and high concentrations of sulfuric and hydrochloric acids, composite materials still exhibit weak corrosion resistance. Therefore, overall, carbon nanotube-based electromagnetic shielding materials still face the problem of poor resistance to strong acid corrosion, and research in this area is relatively limited. Summary of the Invention

[0004] To address the shortcomings of the aforementioned background technology, this invention primarily solves the problem that carbon nanotube-based electromagnetic shielding materials still suffer from poor resistance to strong acid corrosion. This invention provides a flexible, corrosion-resistant carbon nanotube electromagnetic shielding film and its preparation method. The carbon nanotube film consists of a crystalline carbon nanotube film and amorphous pyrolytic carbon. A layer of amorphous pyrolytic carbon is uniformly grown on its surface, and the internal structure consists of individual carbon nanotubes surrounded by amorphous pyrolytic carbon, with amorphous pyrolytic carbon also growing between adjacent carbon nanotubes. Depositing amorphous pyrolytic carbon onto the surface of the original carbon nanotube film prevents corrosion from propagating inward, thereby enhancing the overall corrosion resistance of the film.

[0005] The first objective of this invention is to provide a flexible and corrosion-resistant carbon nanotube electromagnetic shielding film, comprising a crystalline carbon nanotube film and amorphous pyrolytic carbon loaded on both the surface and interior of the crystalline carbon nanotube film.

[0006] The carbon nanotubes in the crystalline carbon nanotube film overlap each other to form a three-dimensional network structure.

[0007] Preferably, the thickness of the crystalline carbon nanotube film is 6–8 μm.

[0008] Preferably, in this carbon nanotube electromagnetic shielding film, a layer of amorphous pyrolytic carbon is grown on the surface of the crystalline carbon nanotube film, and the internal structure is that a single carbon nanotube is surrounded by amorphous pyrolytic carbon, and amorphous pyrolytic carbon is also grown between adjacent carbon nanotubes.

[0009] Preferably, the thickness of the carbon nanotube electromagnetic shielding film is 10-15 μm.

[0010] The second objective of this invention is to provide a method for preparing a flexible, corrosion-resistant carbon nanotube electromagnetic shielding film, comprising the following steps:

[0011] A flexible, corrosion-resistant carbon nanotube electromagnetic shielding film is obtained by growing amorphous pyrolytic carbon on both the surface and inside of a crystalline carbon nanotube film through chemical vapor infiltration or chemical vapor deposition.

[0012] Preferably, the processing temperature of the chemical vapor infiltration or chemical vapor deposition method is 870–900°C, the processing time is 36–48 h, and the processing pressure is 3–5 kPa.

[0013] Preferably, the carbon source used in the chemical vapor infiltration or chemical vapor deposition process includes propylene and / or methane.

[0014] The third objective of this invention is to provide an application of a flexible and corrosion-resistant carbon nanotube electromagnetic shielding film in electromagnetic shielding.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] This invention provides a flexible, corrosion-resistant carbon nanotube electromagnetic shielding film and its preparation method. In this invention, the amorphous pyrolytic carbon itself contains carbon sp. 3 Hybridization, inherently possessing excellent corrosion resistance, prevents corrosion from propagating inward after deposition on the surface of the original carbon nanotube film, thereby enhancing the overall corrosion resistance of the film. In this invention, amorphous pyrolytic carbon and the original carbon nanotubes both belong to carbonaceous materials. During the high-temperature CVI process, pyrolytic carbon and carbon nanotubes can form carbon sp... 3Hybridization further enhances the corrosion resistance of the film, while also improving its structural stability and density. In this invention, pyrolytic carbon, being a carbonaceous material, also possesses lightweight characteristics; therefore, the film retains its lightweight properties even after its introduction. Furthermore, pyrolytic carbon, being a carbonaceous material, also exhibits high electrical conductivity; therefore, the film retains its high electrical conductivity even after its introduction. Attached Figure Description

[0017] Figure 1 This is a scanning electron microscope (SEM) image of the flexible and corrosion-resistant carbon nanotube electromagnetic shielding film prepared in Example 1 of the present invention.

[0018] Figure 2 This is a transmission electron microscope (TEM) image of the flexible and corrosion-resistant carbon nanotube electromagnetic shielding film prepared in Example 1 of the present invention.

[0019] Figure 3 The image shows the Raman spectra of the flexible, corrosion-resistant carbon nanotube electromagnetic shielding film prepared in Example 1 of this invention.

[0020] Figure 4 The stress-strain curve and bending image of the flexible, corrosion-resistant carbon nanotube electromagnetic shielding film prepared in Example 1 of this invention are shown.

[0021] Figure 5 This is a conductivity diagram of the flexible, corrosion-resistant carbon nanotube electromagnetic shielding film prepared in Example 1 of the present invention after corrosion resistance testing.

[0022] Figure 6 This is an electromagnetic shielding effectiveness diagram of the flexible, corrosion-resistant carbon nanotube electromagnetic shielding film prepared in Example 1 of the present invention after corrosion resistance testing.

[0023] Figure 7 The image shows a physical copy of the flexible, corrosion-resistant carbon nanotube electromagnetic shielding film provided in Example 1. Detailed Implementation

[0024] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention.

[0025] The purpose of this invention is to address the problem of carbon nanotube-based electromagnetic shielding materials being susceptible to corrosion by strong acids. Therefore, this invention provides a flexible, corrosion-resistant carbon nanotube electromagnetic shielding film and its preparation method.

[0026] To achieve the above objectives, the first aspect of the present invention provides a flexible and corrosion-resistant carbon nanotube electromagnetic shielding film, comprising a crystalline carbon nanotube film and amorphous pyrolytic carbon loaded on both the surface and interior of the crystalline carbon nanotube film.

[0027] The carbon nanotubes in the crystalline carbon nanotube film overlap each other to form a three-dimensional network structure.

[0028] The carbon nanotube film provided by this invention has good electromagnetic shielding performance, as well as good flexibility and excellent corrosion resistance.

[0029] The thickness of the crystalline carbon nanotube film is 6–8 μm.

[0030] In this carbon nanotube electromagnetic shielding film, a layer of amorphous pyrolytic carbon is grown on the surface of the crystalline carbon nanotube film. The internal structure consists of a single carbon nanotube surrounded by amorphous pyrolytic carbon, and amorphous pyrolytic carbon is also grown between adjacent carbon nanotubes.

[0031] The thickness of this carbon nanotube electromagnetic shielding film is 10-15 μm.

[0032] A second aspect of this invention provides a method for preparing a flexible, corrosion-resistant carbon nanotube electromagnetic shielding film, comprising the following steps:

[0033] A flexible, corrosion-resistant carbon nanotube electromagnetic shielding film is obtained by growing amorphous pyrolytic carbon on both the surface and inside of a crystalline carbon nanotube film through chemical vapor infiltration or chemical vapor deposition.

[0034] The processing temperature of the chemical vapor infiltration or chemical vapor deposition method is 870–900℃, the processing time is 36–48h, and the processing pressure is 3–5kPa.

[0035] In the chemical vapor infiltration or chemical vapor deposition process, the carbon source used includes propylene and / or methane.

[0036] This invention involves uniformly growing pyrolytic carbon on the surface and interior of a crystalline carbon nanotube film, resulting in a carbon nanotube film composed of crystalline carbon nanotubes and amorphous pyrolytic carbon. A layer of amorphous pyrolytic carbon is uniformly grown on the surface, and the internal structure consists of individual carbon nanotubes surrounded by amorphous pyrolytic carbon, with amorphous pyrolytic carbon also growing between adjacent carbon nanotubes. The original carbon nanotube film thickness is 6–8 μm, which increases to 10–15 μm after introducing amorphous pyrolytic carbon. The carbon nanotubes in the film interlock to form a three-dimensional network structure, thereby enhancing the overall corrosion resistance of the film.

[0037] An exemplary method for preparing a flexible, corrosion-resistant carbon nanotube electromagnetic shielding film includes the following steps:

[0038] Crystalline carbon nanotube films were treated using chemical vapor infiltration.

[0039] Amorphous pyrolytic carbon was grown on the surface and inside of the treated crystalline carbon nanotube film, resulting in a flexible and corrosion-resistant carbon nanotube electromagnetic shielding film.

[0040] The chemical vapor infiltration process is carried out at a temperature of 870–900°C for 36–48 hours and at a pressure of 5 kPa. The carbon source used for the process includes propylene (C3H6), methane (CH4), or a combination of the two gases, with propylene being preferred.

[0041] An exemplary method for preparing a flexible, corrosion-resistant carbon nanotube electromagnetic shielding film includes the following steps:

[0042] Crystalline carbon nanotube films were processed by chemical vapor deposition.

[0043] Amorphous pyrolytic carbon was grown on the surface and inside of the treated crystalline carbon nanotube film, resulting in a flexible and corrosion-resistant carbon nanotube electromagnetic shielding film.

[0044] The chemical vapor deposition process is carried out at a temperature of 870–900°C, for a duration of 36–48 h, and at a pressure of 5 kPa. The carbon source used for the process includes propylene (C3H6), methane (CH4), or a combination of the two gases, with propylene being preferred.

[0045] A third aspect of the present invention provides the application of a flexible and corrosion-resistant carbon nanotube electromagnetic shielding film in electromagnetic shielding.

[0046] It should be noted that, unless otherwise specified, the experimental methods used in this invention are all conventional methods; and the reagents and materials used, unless otherwise specified, are all commercially available.

[0047] Example 1

[0048] A method for preparing a flexible, corrosion-resistant carbon nanotube electromagnetic shielding film includes the following steps:

[0049] A 6μm thick virgin carbon nanotube film was placed on a heating platform in a furnace, and propylene, the carbon source, was introduced. The temperature was set to 870℃ and the pressure to 5kPa. The temperature was maintained for 36 hours, and amorphous pyrolytic carbon grew uniformly on the surface and inside of the virgin carbon nanotube film, resulting in a flexible and corrosion-resistant carbon nanotube electromagnetic shielding film, PyC-CNT.

[0050] Example 2

[0051] A method for preparing a flexible, corrosion-resistant carbon nanotube electromagnetic shielding film includes the following steps:

[0052] A 6μm thick virgin carbon nanotube film was placed on a heating platform in a furnace, and propylene, the carbon source, was introduced. The temperature was set to 870℃ and the pressure to 5kPa. The temperature was maintained for 48h, and amorphous pyrolytic carbon grew uniformly on the surface and inside of the virgin carbon nanotube film, resulting in a flexible and corrosion-resistant carbon nanotube electromagnetic shielding film, PyC-CNT-1.

[0053] Example 3

[0054] An 8 μm thick original carbon nanotube film was placed on a heating stage in a furnace, and methane, the carbon source, was introduced. The temperature was set to 870 °C and the pressure to 5 kPa. The temperature was maintained for 36 h, and amorphous pyrolytic carbon was uniformly grown on the surface and inside of the original carbon nanotube film, resulting in sample PyC-CNT-2.

[0055] To illustrate the relevant performance of the flexible corrosion-resistant carbon nanotube electromagnetic shielding film provided by the present invention, the microstructure and performance of the original carbon nanotube film and the prepared flexible corrosion-resistant carbon nanotube electromagnetic shielding film in Example 1 were characterized:

[0056] Figure 1 SEM images of the original carbon nanotube film (CNT) and the flexible, corrosion-resistant carbon nanotube electromagnetic shielding film (PyC-CNT) prepared in Example 1 are shown, both at a magnification of 50,000x. Figure 1 The left image (CNT) shows that in the original carbon nanotube film, individual carbon nanotubes intertwine and form a three-dimensional network structure. This network structure contains particulate impurities, which may be residual metal catalysts. The presence of these impurities affects the electron conduction efficiency within the carbon nanotube network, thus affecting the film's conductivity and ultimately leading to a decrease in the film's electromagnetic shielding effectiveness. After chemical vapor infiltration treatment, from... Figure 1 As shown in the right image (PyC-CNT), a dense layer of pyrolytic carbon is deposited on the surface of the original carbon nanotube film. Since pyrolytic carbon and carbon nanotubes are both carbon materials, when pyrolytic carbon is introduced, carbon sp. formation occurs between the pyrolytic carbon layer and the original carbon nanotube layer. 3 Hybridization, and the bonding mode of pyrolytic carbon itself includes sp. 3 Hybridization, compared to the sp[] of carbon in the original carbon nanotube film. 2 Hybridization, sp 3 Hybridization enhances the bonding force between materials, making them more compact. Therefore, the introduction of pyrolytic carbon improves the overall performance of carbon nanotube films, especially their corrosion resistance.

[0057] Figure 2 TEM images of the flexible, corrosion-resistant carbon nanotube electromagnetic shielding film (PyC-CNT) prepared in Example 1 are shown. Figure 2The film shows single crystalline carbon nanotubes with concentric transmission fringes, surrounded by amorphous pyrolytic carbon. This demonstrates the successful growth of amorphous pyrolytic carbon within the film using chemical vapor infiltration, which encapsulates the crystalline carbon nanotubes. The spaces between the carbon nanotubes are also filled with pyrolytic carbon, thus enhancing the film's structural stability and corrosion resistance.

[0058] Figure 3 Raman spectra of the original carbon nanotube film (CNT) and the flexible, corrosion-resistant carbon nanotube electromagnetic shielding film (PyC-CNT) prepared in Example 1 are shown. It can be seen that both samples exhibit obvious carbon characteristic peaks, including the one at 1340 cm⁻¹. -1 D-band and 1590cm -1 The G band. After the introduction of pyrolytic carbon, the ratio of its D band to G band (I) D / I G The value increased significantly, from 0.284 to 0.903, which means that the degree of graphitization of the sample decreased, corresponding to the introduction of amorphous pyrolytic carbon.

[0059] Figure 4 The stress-strain curves and bending diagrams of the original carbon nanotube film and the flexible, corrosion-resistant carbon nanotube electromagnetic shielding film prepared in Example 1 are shown. It can be seen that after introducing pyrolytic carbon, the maximum tensile stress of the sample increased from 20 MPa to 110 MPa. This is due to the sp3 hybridization of the carbon introduced during pyrolytic carbon introduction, which enhances the bonding force between materials, thereby significantly improving the mechanical properties of the film. Meanwhile, Figure 7 The flexible and corrosion-resistant carbon nanotube electromagnetic shielding film provided in Example 1, through the actual images of bending and rolling, demonstrates that the film exhibits excellent flexibility, can adapt to various complex shaped surfaces, and thus provides electromagnetic shielding function.

[0060] Figure 5 The conductivity graphs of the original carbon nanotube film and the flexible, corrosion-resistant carbon nanotube electromagnetic shielding film prepared in Example 1 after corrosion testing are shown. The corrosion test environment included chlorosulfonic acid solution (CSA, 99 wt%), sulfuric acid solution (95%–98% wt%), and hydrochloric acid solution (36%–38% wt%), with a corrosion time of 45 days. Specifically, the film was completely immersed in a glass bottle containing the above solutions for 45 days. It can be seen that the conductivity of the flexible, corrosion-resistant carbon nanotube electromagnetic shielding film prepared in Example 1 is improved compared to the original carbon nanotube film. This is attributed to the increased conductivity of carbon introduced through pyrolysis. 3Hybridization makes the film structure more compact, enhancing electron transport efficiency. The conductivity of the film further improves after corrosion testing because immersion removes particulate impurities from the original carbon nanotube film, thus enhancing electron transport efficiency. The greatest increase in conductivity occurs after treatment with chlorosulfonic acid solution. This is because chlorosulfonic acid has high polarity; treatment with it induces charge separation on individual carbon nanotubes, creating positive and negative charge regions. This increases the number of positive and negative charge sites on the tubes. Under the influence of Coulomb's charge and van der Waals forces, the number of connection sites between carbon nanotubes increases, resulting in tighter connections and a densification effect. Furthermore, the increased number of connection sites between carbon nanotubes leads to faster electron transport, significantly improving conductivity.

[0061] Figure 6 The electromagnetic shielding effectiveness of the carbon nanotube film prepared in Example 1 in the X-ray band is demonstrated. It can be seen that the flexible, corrosion-resistant carbon nanotube electromagnetic shielding film prepared in Example 1 exhibits excellent electromagnetic shielding and corrosion resistance, with a maximum shielding effectiveness of 48.8 dB. Furthermore, as theoretically analyzed, the deposition of pyrolytic carbon enhances the corrosion resistance of the carbon nanotube film, and the electromagnetic shielding performance is further improved after 45 days of acid solution corrosion. In particular, the prepared flexible, corrosion-resistant carbon nanotube electromagnetic shielding film withstood prolonged corrosion by chlorosulfonic acid solution, and the electromagnetic shielding effectiveness of the film after corrosion increased to a maximum of 57 dB.

[0062] In summary, this invention provides a flexible, corrosion-resistant carbon nanotube electromagnetic shielding film and its preparation method. Specifically, a crystalline carbon nanotube film is treated by chemical vapor infiltration, resulting in the growth of amorphous pyrolytic carbon on the surface and inside of the treated carbon nanotube film, thereby obtaining a flexible, corrosion-resistant carbon nanotube electromagnetic shielding film. The flexible, corrosion-resistant carbon nanotube electromagnetic shielding film prepared by this invention exhibits excellent flexibility, demonstrates a shielding effectiveness of up to 48.8 dB in the X-ray band, and can withstand prolonged corrosion from high-concentration acid solutions. Furthermore, its shielding effectiveness is further enhanced after acid solution corrosion, thus it holds promise for applications in the field of electromagnetic shielding.

[0063] This invention describes preferred embodiments and their effects. However, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to include both the preferred embodiments and all changes and modifications falling within the scope of this invention.

[0064] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A flexible corrosion resistant carbon nanotube electromagnetic shielding film, characterized by, The crystal carbon nanotube film and the amorphous pyrolytic carbon loaded on the surface and inside of the crystal carbon nanotube film; The carbon nanotubes in the crystal carbon nanotube film are connected to each other to form a three-dimensional network structure; The thickness of the crystal carbon nanotube film is 6-8 μm; The carbon nanotube electromagnetic shielding film has a layer of amorphous pyrolytic carbon grown on the surface of the crystal carbon nanotube film, and the internal structure is that a single carbon nanotube is surrounded by amorphous pyrolytic carbon, and amorphous pyrolytic carbon also grows between adjacent carbon nanotubes; The thickness of the carbon nanotube electromagnetic shielding film is 10-15 μm; The flexible corrosion-resistant carbon nanotube electromagnetic shielding film is prepared by the following steps: The crystal carbon nanotube film is subjected to chemical vapor infiltration or chemical vapor deposition to grow amorphous pyrolytic carbon on the surface and inside of the film, thereby obtaining the flexible corrosion-resistant carbon nanotube electromagnetic shielding film; The treatment temperature of the chemical vapor infiltration or chemical vapor deposition is 870-900℃, the treatment time is 36-48 h, and the treatment pressure is 3-5 kPa; During the treatment by the chemical vapor infiltration or chemical vapor deposition, the carbon source includes propylene and / or methane.

2. A method of producing the flexible corrosion-resistant carbon nanotube electromagnetic shielding film according to claim 1, characterized by, The steps include: The crystal carbon nanotube film is subjected to chemical vapor infiltration or chemical vapor deposition to grow amorphous pyrolytic carbon on the surface and inside of the film, thereby obtaining the flexible corrosion-resistant carbon nanotube electromagnetic shielding film; The treatment temperature of the chemical vapor infiltration or chemical vapor deposition is 870-900℃, the treatment time is 36-48 h, and the treatment pressure is 3-5 kPa; During the treatment by the chemical vapor infiltration or chemical vapor deposition, the carbon source includes propylene and / or methane.

3. The flexible corrosion-resistant carbon nanotube electromagnetic shielding film according to claim 1 is applied in electromagnetic shielding.

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