Nickel-plated carbon nanotube and electromagnetic protection composite film and preparation method thereof

Abstract

The application relates to the technical field of electromagnetic shielding materials, in particular to a nickel-plated carbon nanotube, an electromagnetic protection composite film and a preparation method thereof, and a nickel plating solution for nickel plating of carbon nanotubes. The preparation method of the electromagnetic protection composite film provided by the application comprises the following steps: providing carbon nanotubes; adopting a nickel plating solution to perform chemical nickel plating on the carbon nanotubes to prepare a nickel-plated carbon nanotube dispersion liquid; the composition of the nickel plating solution comprises a divalent nickel salt, a complexing agent, a reducing agent, a buffer and a pH regulator; and the nickel-plated carbon nanotube dispersion liquid is prepared into an electromagnetic protection composite film through vacuum suction filtration. The obtained electromagnetic protection composite film has good electric field and magnetic field shielding efficiency, and has good bending resistance and uniform texture, and is suitable for conformal covering on the surfaces of complex structures.

Description

Technical Field

[0001] This application belongs to the field of electromagnetic shielding materials technology, and particularly relates to a nickel-plated carbon nanotube, an electromagnetic protection composite film and its preparation method, as well as a nickel plating solution for carbon nanotubes. Background Technology

[0002] Some facilities (such as railway control systems, power grid facilities, medical facilities, large industrial installations, and specialized water transportation facilities) often contain a large number of cable bundles and electronic equipment. With the increasing number and integration of electronic equipment, more electronic devices are operating within smaller spaces. While this brings convenience and efficiency, the normal operation of these devices creates a highly complex internal electromagnetic environment. Furthermore, the high-power equipment they house also radiates significant amounts of electromagnetic radiation during operation. In addition, these facilities often operate in environments with strong electromagnetic pulses. Without proper electromagnetic protection, such a complex electromagnetic environment can affect the normal operation of the facilities, thereby jeopardizing overall safety. Moreover, the electromagnetic radiation within these facilities can also impact the health and safety of workers. Therefore, this presents a significant challenge to the electromagnetic protection capabilities of the equipment within these facilities in complex electromagnetic environments.

[0003] In the selection of protective materials, iron, copper, aluminum, and manganese are the most widely used and have the most stable performance. However, metallic materials have significant drawbacks in environments with high humidity and salt spray. Therefore, carbon fiber composites, with their excellent environmental corrosion resistance and weight reduction effect, have been increasingly used. However, some protective targets have complex outer shell structures, making it difficult to cure carbon fiber composites. A relatively effective electromagnetic pulse protection method is to cover the surface of complex structures with carbon fiber woven fabric to achieve electromagnetic protection. However, the millimeter-sized gaps in carbon fiber woven fabric can cause a significant decrease in shielding effectiveness above 20 GHz, and its shielding effectiveness against magnetic fields is also not ideal. Although research on electromagnetic protection materials has made some progress, there are still problems such as narrow operating frequency bands, insufficient shielding performance, inconvenience of using spray coating inside the enclosure, and the risk of damaging electronic equipment. Summary of the Invention

[0004] The purpose of this application is to provide an electromagnetic shielding composite film and its preparation method, as well as a carbon nanotube nickel plating solution, in order to solve the problem of how to provide an electromagnetic shielding material that is corrosion resistant and has good shielding performance.

[0005] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows:

[0006] In a first aspect, this application provides a method for preparing nickel-plated carbon nanotubes, comprising: providing carbon nanotubes; chemically plating the carbon nanotubes with a nickel plating solution to prepare a nickel-plated carbon nanotube dispersion; the nickel plating solution comprises: divalent nickel salt, complexing agent, reducing agent, buffer, and pH adjuster; and performing solid-liquid separation on the nickel-plated carbon nanotube dispersion to obtain nickel-plated carbon nanotubes.

[0007] This application employs a nickel plating solution containing divalent nickel salt, complexing agent, reducing agent, buffer, and pH adjuster to plate nickel onto carbon nanotubes, resulting in excellent electric and magnetic field shielding performance, making it suitable for strong electromagnetic pulse environments. This electromagnetic protection composite film uses carbon nanotubes as the substrate and divalent nickel as the main salt in the nickel plating solution, exhibiting good environmental corrosion resistance and suitable for environments with high humidity and salt spray.

[0008] Secondly, this application provides a method for preparing an electromagnetic protection composite membrane, wherein a purified nickel-plated carbon nanotube dispersion is prepared from the nickel-plated carbon nanotubes in the above-mentioned method for preparing nickel-plated carbon nanotubes, and the purified nickel-plated carbon nanotube dispersion is vacuum filtered to prepare an electromagnetic protection composite membrane.

[0009] The preparation method provided in this application provides an electromagnetic shielding composite film that is suitable for bonding to the surface of equipment, has corrosion resistance, and exhibits good electrical and magnetic shielding performance.

[0010] Thirdly, this application provides an electromagnetic protection composite film.

[0011] The nickel-plated carbon nanotube composite film provided in this application, as an electromagnetic shielding composite film, possesses an electric and magnetic field shielding effectiveness of over 40dB within a wide frequency range of 20MHz to 40GHz. The prepared nickel-plated carbon nanotube film exhibits good bending resistance and uniform texture, and can effectively cover complex structural surfaces. It can be used alone or in combination with other shielding films.

[0012] Fourthly, this application provides a nickel plating solution for nickel plating of carbon nanotubes, comprising: divalent nickel salt, complexing agent, reducing agent, buffer, and pH adjuster; the concentration of divalent nickel salt is 0.01 mol / L to 0.05 mol / L; and / or, the pH of the nickel plating solution is 8 to 12.

[0013] The nickel plating solution provided in this application is used to plate nickel onto carbon nanotubes to obtain a carbon nanotube dispersion, which can be used to form a film for preparing an electromagnetic protection composite film. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a flowchart illustrating the process for preparing nickel-plated carbon nanotubes according to an embodiment of this application;

[0016] Figure 2 This is a process flow diagram of the preparation process of nickel-plated carbon nanotube thin films according to an embodiment of this application;

[0017] Figure 3 This is an image showing the appearance morphology of the nickel-plated carbon nanotube film provided in the embodiments of this application;

[0018] Figure 4 This is a shielding effectiveness diagram of the nickel-plated carbon nanotube film provided in the embodiments of this application;

[0019] Figure 5 This is a conductivity measurement diagram of the nickel-plated carbon nanotube thin film provided in the embodiments of this application;

[0020] Figure 6 This is a diagram showing the magnetic shielding effectiveness of nickel-plated carbon nanotube films obtained from nickel sulfate of different concentrations, as provided in the embodiments of this application.

[0021] Figure 7 This is a diagram showing the magnetic shielding effectiveness of nickel-plated carbon nanotube films obtained from different plating solution pH values, as provided in the embodiments of this application.

[0022] Figure 8 This is a diagram showing the magnetic shielding effectiveness of nickel-plated carbon nanotube films obtained at different nickel plating temperatures, provided in the embodiments of this application.

[0023] Figure 9 This is a magnetic shielding effectiveness diagram of nickel-plated carbon nanotube films obtained from different filter membrane pore sizes, provided in the embodiments of this application. Detailed Implementation

[0024] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0025] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0026] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0027] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0028] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0029] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a mass unit known in the chemical industry, such as μg, mg, g, or kg.

[0030] The terms "first" and "second" are used for descriptive purposes only, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. For example, without departing from the scope of the embodiments of this application, "first XX" may also be referred to as "second XX," and similarly, "second XX" may also be referred to as "first XX." Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0031] The first aspect of this application provides a method for preparing nickel-plated carbon nanotubes, comprising: providing carbon nanotubes; chemically plating the carbon nanotubes with a nickel plating solution to prepare a nickel-plated carbon nanotube dispersion; the nickel plating solution comprises: divalent nickel salt, complexing agent, reducing agent, buffer, and pH adjuster; and performing solid-liquid separation on the nickel-plated carbon nanotube dispersion to obtain nickel-plated carbon nanotubes.

[0032] This application embodiment uses a nickel plating solution containing divalent nickel salt, complexing agent, reducing agent, buffer, and pH adjuster to plate carbon nanotubes with nickel, which has good electric field shielding and magnetic field shielding performance and can be used in strong electromagnetic pulse environments. The electromagnetic protection composite film uses carbon nanotubes as the substrate and divalent nickel as the main salt in the nickel plating solution, which has good environmental corrosion resistance and can be used in environments with high humidity and salt spray.

[0033] In this embodiment, divalent nickel salt serves as the main salt in the nickel plating solution, acting as a source of divalent metal ions and enhancing the shielding capabilities of the composite thin film's electric and magnetic fields. Maintaining a certain concentration in the solution enables continuous nickel plating. A complexing agent generates stable metal ion complexes to maintain the stability and uniform distribution of nickel ions during the electroless plating process, ensuring its smooth operation. A reducing agent reduces divalent nickel ions to metallic nickel. A buffering agent is used to maintain the pH of the solution as H+ ions are generated during the plating process, causing a gradual decrease in pH. To stabilize the plating rate and ensure coating quality, the plating solution must possess pH buffering capacity. This embodiment employs a buffering agent to maintain the pH stability of the electroless plating solution and promote nickel precipitation. A pH adjuster is used to adjust the pH of the nickel plating solution within a set range.

[0034] In some embodiments, the step of solid-liquid separation of nickel-plated carbon nanotube dispersion to obtain nickel-plated carbon nanotubes includes: filtration, cleaning and drying.

[0035] Furthermore, the filtration process includes filtering the nickel-plated carbon nanotube dispersion using a filter membrane (specifically, polytetrafluoroethylene (PTFE) with a pore size of 0.05 μm).

[0036] Furthermore, the cleaning process includes: rinsing the filtered nickel-plated carbon nanotubes multiple times with deionized water, and then ultrasonically cleaning the nickel-plated carbon nanotubes with deionized water.

[0037] Further, the drying process includes drying at a temperature of 80℃~100℃ for 4h~6h to obtain nickel-plated carbon nanotubes.

[0038] In some embodiments, the obtained nickel-plated carbon nanotubes are used to prepare a nickel-plated carbon nanotube dispersion, and a membrane material is prepared by a wet process.

[0039] In some embodiments, the concentration of divalent nickel salt in the nickel plating solution is 0.01 mol / L to 0.05 mol / L; and / or, the pH of the nickel plating solution is 8 to 12.

[0040] In nickel plating solutions, the concentration of divalent nickel salts ranges from 0.01 mol / L to 0.05 mol / L. Specific examples show concentrations of 0.01 mol / L, 0.02 mol / L, 0.03 mol / L, 0.04 mol / L, or 0.05 mol / L, etc.

[0041] The pH of the nickel plating solution is 8–12. In specific examples, the pH of the nickel plating solution is 8, 9, 10, 11, or 12, etc.

[0042] This application embodiment improves the electromagnetic shielding performance of the electromagnetic protection composite film by reasonably setting the concentration of divalent nickel salt in the nickel plating solution, resulting in a composite film with better bending resistance and uniform texture, which can effectively cover complex structural surfaces.

[0043] On the one hand, a higher concentration of primary salt can provide more nickel ions, promoting rapid deposition. However, excessively high nickel salt concentrations may have some adverse effects: 1) It can lead to coarse crystallization of the coating, forming larger grains, which may reduce the continuity and uniformity of the nickel plating layer, thus affecting its conductivity and electromagnetic wave absorption / reflection capabilities, ultimately weakening electromagnetic shielding performance. An excessively thick or structurally uneven nickel layer may increase the weight and volume of the material. 2) It can lead to excessive growth of the nickel plating layer, blocking the openings of carbon nanotubes, reducing the effective contact area, and thus affecting the wettability of the nickel plating layer with other matrix materials, reducing the overall performance of the composite material. 3) It can reduce the uniformity of the nickel plating layer. Inhomogeneity in the nickel plating layer may form micropores or cracks, which are channels for corrosive media penetration, accelerating the corrosion process over time and reducing overall corrosion resistance. On the other hand, excessively low primary salt concentrations may lead to uneven coverage of the coating on the carbon nanotube surface, affecting the uniformity and adhesion of the coating. The hardness, wear resistance, and corrosion resistance of the electroless nickel plating layer may be affected by excessively low primary salt concentrations, potentially failing to meet the expected application performance requirements. In addition, a low concentration of the main salt makes it more difficult to control the coating thickness and achieve the required thickness specifications.

[0044] This application embodiment improves the electromagnetic shielding performance of the electromagnetic protection composite film by reasonably setting the pH value of the nickel plating solution, resulting in a composite film with better bending resistance and uniform texture, which can be well covered on complex structural surfaces.

[0045] On the one hand, an excessively high pH value in the nickel plating solution can lead to a decline in the quality of the nickel plating layer, such as cracking and peeling. Furthermore, an excessively high pH value may affect the activity of metal ions and reducing agents in the plating solution, thus impacting the deposition rate. On the other hand, an excessively low pH value in the nickel plating solution can result in an uneven nickel plating layer with increased porosity, affecting the density and corrosion resistance of the coating. Additionally, an excessively low pH value may reduce the rate of chemical reactions, thereby slowing down the reduction and deposition rates of metal ions.

[0046] Furthermore, the concentration of divalent nickel salt in the nickel plating solution is 0.03 mol / L to 0.05 mol / L.

[0047] Furthermore, the pH of the nickel plating solution is 10–12.

[0048] In some embodiments, the concentration of nickel sulfate is 0.04 mol / L to 0.05 mol / L; and / or, the pH of the nickel plating solution is 10 to 12.

[0049] In some embodiments, the nickel plating solution has at least one of the following features (1) to (6):

[0050] (1) The concentration of the complexing agent is 0.05 mol / L to 0.1 mol / L;

[0051] (2) The concentration of the reducing agent is 0.13 mol / L to 0.20 mol / L;

[0052] (3) The concentration of the buffer is 0.05 mol / L to 0.1 mol / L;

[0053] (4) Divalent nickel salts include at least one of nickel sulfate and nickel chloride;

[0054] (5) The complexing agent includes at least one of trisodium citrate (Na3C6H5O7), ethylenediaminetetraacetic acid (C10H16N2O8), monosodium citrate (Na3C6H5O7) and disodium citrate (Na2C6H5O7);

[0055] (6) The reducing agent includes sodium hypophosphite (NaH2PO2).

[0056] The higher the concentration of the reducing agent (such as sodium hypophosphite), the stronger its reducing power and the faster the reaction rate, thus increasing the deposition rate. When the reducing agent coexists with nickel ions, it promotes nickel deposition and may form a nickel-phosphorus alloy layer, which can improve the coating's properties, such as hardness and wear resistance. By rationally designing the concentration of divalent nickel salts, i.e., rationally designing the nickel ion concentration, the reduction effect of the reducing agent can be promoted.

[0057] In specific examples, the concentration of the complexing agent is 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L, or 0.10 mol / L, etc.

[0058] In specific examples, the concentration of the reducing agent is 0.13 mol / L, 0.14 mol / L, 0.15 mol / L, 0.16 mol / L, 0.17 mol / L, 0.18 mol / L, 0.19 mol / L, or 0.20 mol / L, etc.

[0059] In specific examples, the concentration of the buffer is 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L, or 0.10 mol / L, etc.

[0060] In the embodiments of this application, the divalent nickel salt includes at least one of nickel sulfate and nickel chloride; it can be an anhydrous metal salt or a hydrated metal salt; hydrated metal salts include NiSO4·6H2O and / or NiCl4·6H2O.

[0061] In some embodiments, the nickel plating solution has at least one of the following features (1) to (3):

[0062] The concentration of the complexing agent is 0.06 mol / L;

[0063] The concentration of the reducing agent is 0.16 mol / L;

[0064] The concentration of the buffer is 0.06 mol / L.

[0065] In some embodiments, the buffer includes at least one of ammonium sulfate ((NH4)2SO4), ammonium chloride (NH4Cl), sodium phosphate (Na3PO4), and disodium hydrogen phosphate (Na2HPO4).

[0066] In some embodiments, the pH adjuster includes ammonia.

[0067] In some embodiments, the electroless nickel plating process includes mixing a nickel plating solution and carbon nanotubes and then plating the solution at a temperature of 50°C to 70°C. Specific examples include temperatures of 52°C, 54°C, 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, 68°C, and 70°C.

[0068] During the nickel plating process, most of the oxidation and reduction reactions require endothermic reaction. Setting a reasonable temperature will promote the occurrence of catalytic reaction and ensure that the nickel plating reaction proceeds effectively.

[0069] Furthermore, in the step of electroless nickel plating of carbon nanotubes using a nickel plating solution, the temperature is 55℃~65℃.

[0070] Furthermore, in the step of electroless nickel plating of the carbon nanotubes using a nickel plating solution, the temperature is 60°C.

[0071] In some embodiments, electroless nickel plating includes: adding divalent nickel salt, reducing agent, complexing agent and buffer to carbon nanotubes or carbon nanotube dispersion, stirring and mixing, adjusting the pH to a set value using a pH adjuster to obtain a mixed solution; then, condensing the mixed solution under constant temperature stirring to complete the electroless nickel plating, thereby preparing a nickel-plated carbon nanotube dispersion.

[0072] Furthermore, the condensation reflux treatment time is 40 min to 50 min.

[0073] In some embodiments, before electroless nickel plating of the carbon nanotubes using a nickel plating solution, the method further includes: sequentially subjecting the carbon nanotubes to oxidation purification, sensitization, and activation treatments.

[0074] In some embodiments, the step of providing carbon nanotubes includes: providing raw carbon nanotube material; oxidizing and purifying the raw carbon nanotube material; sensitizing the oxidized and purified carbon nanotubes; activating the sensitized carbon nanotubes; and using the carbon nanotube dispersion obtained after activation treatment for electroless nickel plating with a nickel plating solution.

[0075] The embodiments of this application utilize oxidation purification treatment to remove organic contaminants, residual catalyst particles, and other impurities from the surface of carbon nanotubes, thereby improving the dispersibility of carbon nanotubes.

[0076] The embodiments of this application utilize sensitization treatment to facilitate the formation of a catalytic seed layer on the surface of carbon nanotubes. This catalytic seed layer serves as an active site for reducing nickel ions, thereby promoting the deposition of nickel metal on the surface of carbon nanotubes.

[0077] The embodiments of this application utilize activation treatment to increase the number of active sites on the surface, thereby improving its dispersibility in solvents and its compatibility with other materials.

[0078] In some embodiments, the step of providing carbon nanotubes satisfies at least one of the following (1) to (3):

[0079] (1) In the oxidation purification process, the oxidation purification reagents used include nitric acid;

[0080] (2) In the sensitization treatment, the sensitizing reagents used include at least one of stannous chloride (SnCl2), tetrabutyl titanate (C16H36O4Ti) and titanium chloride (TiCl4);

[0081] (3) In the activation process, the activation reagents used include at least one of sodium borohydride (NaBH4) and palladium chloride (PbCl2).

[0082] In some embodiments, the concentration of the sensitizing agent is 0.05 mol / L to 0.2 mol / L; the concentration of the activating agent is 1.5 × 10⁻³ mol / L to 2 × 10⁻³ mol / L.

[0083] In the embodiments of this application, the concentrations of the sensitizing reagent and the activating reagent are calculated based on the total volume of the nickel plating solution.

[0084] In some embodiments, the step of providing carbon nanotubes satisfies at least one of the following (1) to (3):

[0085] (1) In the oxidation purification process, the oxidative purification reagent used is nitric acid;

[0086] (2) In the sensitization treatment, the sensitizing reagent used is stannous chloride;

[0087] (3) In the activation process, the activating reagent used is palladium chloride.

[0088] In some embodiments, the step of providing carbon nanotubes includes:

[0089] Oxidation purification treatment: Mix carbon nanotubes with oxidation purification reagent, perform oxidation purification treatment, then wash with water and filter until the filtered water is neutral, and then dry to obtain oxidized and purified carbon nanotubes.

[0090] Sensitization treatment: The carbon nanotubes after oxidation and purification were dispersed in water; hydrochloric acid and sensitizing reagent were added for sensitization treatment.

[0091] Activation treatment: After the sensitization treatment is completed, an activation reagent is added for further activation treatment. Then, water is used to wash and filter until the filtered water is neutral to obtain a carbon nanotube dispersion, which can be directly used for vacuum filtration to form a film.

[0092] Furthermore, the step of providing carbon nanotubes includes:

[0093] Oxidation purification treatment: Carbon nanotubes and oxidation purification reagents are mixed and subjected to oxidation purification treatment under heating conditions. Then, the mixture is washed with water and filtered until the filtered water is neutral. Finally, the carbon nanotubes are dried to obtain the oxidized and purified carbon nanotubes.

[0094] Sensitization treatment: The carbon nanotubes after oxidation and purification were dispersed in water and ultrasonically treated; then hydrochloric acid was added under stirring, followed by sensitizing reagent, mixed, and sensitized under ultrasonic conditions.

[0095] Activation treatment: After sensitization treatment, an activation reagent is added and mixed. The mixture is then activated under ultrasonic conditions. After washing with water and filtering until the filtered water is neutral, a carbon nanotube dispersion is obtained, which can be directly used for vacuum filtration to form a film.

[0096] Furthermore, during the oxidation purification process, the heating temperature is 55℃~65℃.

[0097] Furthermore, during the oxidation purification process, the drying temperature is 80℃~100℃, and the drying time is 4h~6h.

[0098] The second aspect of this application provides a method for preparing an electromagnetic protection composite film, wherein a purified nickel-plated carbon nanotube dispersion is prepared from the nickel-plated carbon nanotubes in the above-mentioned method for preparing nickel-plated carbon nanotubes, and the purified nickel-plated carbon nanotube dispersion is vacuum filtered to prepare an electromagnetic protection composite film.

[0099] Specifically,

[0100] The preparation method of the electromagnetic shielding composite film includes:

[0101] Provide carbon nanotubes;

[0102] The carbon nanotubes were chemically nickel-plated using a nickel plating solution to prepare a nickel-plated carbon nanotube dispersion. The nickel plating solution consisted of divalent nickel salt, complexing agent, reducing agent, buffer, and pH adjuster.

[0103] Nickel-plated carbon nanotubes were obtained by solid-liquid separation of the nickel-plated carbon nanotube dispersion.

[0104] A purified nickel-plated carbon nanotube dispersion was prepared.

[0105] An electromagnetic protection composite membrane was prepared by vacuum filtration of a purified nickel-plated carbon nanotube dispersion.

[0106] The embodiments of this application aim to provide an electromagnetic protection material that is suitable for bonding to the surface of equipment, has corrosion resistance, and good shielding performance.

[0107] This application embodiment uses a nickel plating solution containing divalent nickel salt, complexing agent, reducing agent, buffer, and pH adjuster to plate nickel onto carbon nanotubes and prepare a thin film structure. This structure has good electric field shielding and magnetic field shielding performance and is suitable for strong electromagnetic pulse environments. The electromagnetic protection composite film has a high Young's modulus and a low areal density, and its texture is uniform. It can achieve weight reduction while also adhering well to the surface of the equipment structure. In addition, the electromagnetic protection composite film uses carbon nanotubes as the substrate and divalent nickel as the main salt in the nickel plating solution, which has good environmental corrosion resistance and is suitable for environments with high humidity and salt spray.

[0108] In this embodiment, divalent nickel salt serves as the main salt in the nickel plating solution, acting as a source of divalent metal ions and enhancing the shielding capabilities of the composite thin film's electric and magnetic fields. Maintaining a certain concentration in the solution enables continuous nickel plating. A complexing agent generates stable metal ion complexes to maintain the stability and uniform distribution of nickel ions during the electroless plating process, ensuring its smooth operation. A reducing agent reduces divalent nickel ions to metallic nickel. A buffering agent is used to maintain the pH of the solution as H+ ions are generated during the plating process, causing a gradual decrease in pH. To stabilize the plating rate and ensure coating quality, the plating solution must possess pH buffering capacity. This embodiment employs a buffering agent to maintain the pH stability of the electroless plating solution and promote nickel precipitation. A pH adjuster is used to adjust the pH of the nickel plating solution within a set range.

[0109] In this embodiment, the nickel-plated carbon nanotubes obtained by the above preparation method can also be configured into a dispersion, and then the electromagnetic protection composite film material can be prepared by wet process.

[0110] In some embodiments, the step of solid-liquid separation of nickel-plated carbon nanotube dispersion to obtain nickel-plated carbon nanotubes includes: filtration, cleaning and drying.

[0111] Furthermore, the filtration process includes filtering the nickel-plated carbon nanotube dispersion using a filter membrane (specifically, polytetrafluoroethylene (PTFE) with a pore size of 0.05 μm).

[0112] Furthermore, the cleaning process includes: rinsing the filtered nickel-plated carbon nanotubes multiple times with deionized water, and then ultrasonically cleaning the nickel-plated carbon nanotubes with deionized water.

[0113] Further, the drying process includes drying at a temperature of 80℃~100℃ for 4h~6h to obtain nickel-plated carbon nanotubes.

[0114] In some embodiments, the obtained nickel-plated carbon nanotubes are prepared into a nickel-plated carbon nanotube dispersion, and a membrane material is prepared by a wet process.

[0115] In a specific example, nickel-plated carbon nanotubes and deionized water are mixed and ultrasonically vibrated to obtain a pure nickel-plated carbon nanotube dispersion. The nickel-plated carbon nanotube dispersion can be further used to prepare nickel-plated carbon nanotube films.

[0116] In some embodiments, the filter membrane used for vacuum filtration has a pore size of 0.1 μm to 0.8 μm.

[0117] By setting the filter membrane pore size appropriately, it is beneficial to achieve uniform and efficient film formation of nickel-plated carbon nanotube dispersion.

[0118] On the one hand, excessively large pore sizes in the filter membrane may result in an insufficiently dense electromagnetic shielding composite membrane structure, leading to a loose structure, reduced mechanical strength, and susceptibility to cracking or deformation, thus resulting in poor structural stability and durability. On the other hand, excessively small pore sizes in the filter membrane may affect the connectivity between carbon nanotubes and the continuity of the nickel plating layer, thereby impacting the magnetic field shielding effectiveness of the composite membrane.

[0119] In specific examples, the pore sizes of the filter membranes are 0.1μm, 0.2μm, 0.22μm, 0.3μm, 0.4μm, 0.45μm, 0.5μm, 0.6μm, 0.65μm, 0.7μm, 0.75μm, and 0.8μm, etc.

[0120] Furthermore, the filter membrane used in vacuum filtration has a pore size of 0.1μm to 0.65μm.

[0121] In some embodiments, the step of preparing an electromagnetic protection composite membrane by vacuum filtration of a nickel-plated carbon nanotube dispersion includes:

[0122] A wet film was obtained from a nickel-plated carbon nanotube dispersion using a vacuum filtration method.

[0123] The obtained wet film is dried to prepare a nickel-plated carbon nanotube film, which is the electromagnetic protection composite film.

[0124] Furthermore, the drying temperature is 80℃~100℃, and the drying time is 4h~6h.

[0125] Furthermore, the steps for preparing an electromagnetic shielding composite membrane by vacuum filtration of a nickel-plated carbon nanotube dispersion include:

[0126] Place the filter between the vacuum pump and the receiver, ensuring all connections are sealed;

[0127] Place a filter membrane on the filter plate of the filtration device;

[0128] Turn on the vacuum pump to create a negative pressure environment and force the solution through the filter membrane;

[0129] Take a nickel-plated carbon nanotube dispersion and place it in a filtration device, allowing it to pass through a filter membrane under vacuum.

[0130] Once the nickel-plated carbon nanotube dispersion has been filtered and the film is relatively wet, remove it and place it in a drying oven to dry. Take out the film to obtain the nickel-plated carbon nanotube film, which is the electromagnetic protection composite film.

[0131] Furthermore, the filter membrane includes polytetrafluoroethylene (PTFE).

[0132] The third aspect of this application provides an electromagnetic protection composite film, which includes nickel-plated carbon nanotubes, and the nickel-plated carbon nanotubes are prepared by the above-described method for preparing nickel-plated carbon nanotubes; or, the electromagnetic protection composite film is prepared by the above-described method for preparing electromagnetic protection composite film.

[0133] The electromagnetic shielding composite film provided in this application is suitable for bonding to the surface of equipment, has corrosion resistance, and has good electrical and magnetic shielding performance.

[0134] The nickel-plated carbon nanotube composite film provided in this application serves as an electromagnetic shielding composite film, possessing an electric and magnetic field shielding effectiveness exceeding 40dB within a wide frequency range of 20MHz to 40GHz. The prepared nickel-plated carbon nanotube film exhibits excellent bending resistance and uniform texture, allowing it to effectively cover complex structural surfaces. It can be used alone or in combination with other shielding films.

[0135] The fourth aspect of this application provides a nickel plating solution for nickel plating of carbon nanotubes, comprising: divalent nickel salt, complexing agent, reducing agent, buffer, and pH adjuster; the concentration of the divalent nickel salt is 0.01 mol / L to 0.05 mol / L; and / or, the pH of the nickel plating solution is 8 to 12.

[0136] In nickel plating solutions, the concentration of divalent nickel salts ranges from 0.01 mol / L to 0.05 mol / L. Specific examples show concentrations of 0.01 mol / L, 0.02 mol / L, 0.03 mol / L, 0.04 mol / L, or 0.05 mol / L, etc.

[0137] The pH of the nickel plating solution is 8–12. In specific examples, the pH of the nickel plating solution is 8, 9, 10, 11, or 12, etc.

[0138] This application embodiment improves the electromagnetic shielding performance of the electromagnetic protection composite film by reasonably setting the concentration of divalent nickel salt in the nickel plating solution, resulting in a composite film with better bending resistance and uniform texture, which can effectively cover complex structural surfaces.

[0139] This application embodiment improves the electromagnetic shielding performance of the electromagnetic protection composite film by reasonably setting the pH value of the nickel plating solution, resulting in a composite film with better bending resistance and uniform texture, which can be well covered on complex structural surfaces.

[0140] The nickel plating solution provided in this application embodiment is used to plate nickel onto carbon nanotubes to obtain a carbon nanotube dispersion, which is then used to form an electromagnetic shielding composite film.

[0141] In some embodiments, the nickel plating solution comprises at least one of the following (1) to (6):

[0142] (1) The concentration of the complexing agent is 0.05 mol / L to 0.1 mol / L;

[0143] (2) The concentration of the reducing agent is 0.13 mol / L to 0.20 mol / L;

[0144] (3) The concentration of the buffer is 0.05 mol / L to 0.1 mol / L;

[0145] (4) Divalent nickel salts include at least one of nickel sulfate and nickel chloride;

[0146] (5) The complexing agent includes at least one of trisodium citrate, ethylenediaminetetraacetic acid, monosodium citrate and disodium citrate;

[0147] (6) The reducing agent includes sodium hypophosphite.

[0148] In specific examples, the concentration of the complexing agent is 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L, or 0.10 mol / L, etc.

[0149] In specific examples, the concentration of the reducing agent is 0.13 mol / L, 0.14 mol / L, 0.15 mol / L, 0.16 mol / L, 0.17 mol / L, 0.18 mol / L, 0.19 mol / L, or 0.20 mol / L, etc.

[0150] In specific examples, the concentration of the buffer is 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L, or 0.10 mol / L, etc.

[0151] In the embodiments of this application, the divalent nickel salt includes at least one of nickel sulfate and nickel chloride; it can be an anhydrous metal salt or a hydrated metal salt; hydrated metal salts include NiSO4·6H2O and / or NiCl4·6H2O.

[0152] In some embodiments, the buffer includes at least one of ammonium sulfate ((NH4)2SO4), ammonium chloride (NH4Cl), sodium phosphate (Na3PO4), and disodium hydrogen phosphate (Na2HPO4).

[0153] In some embodiments, the pH adjuster includes ammonia.

[0154] The following description is based on specific embodiments.

[0155] 1. Materials

[0156] As shown in Table 1, the chemical names, chemical formulas, manufacturers, and necessary physical properties of the materials required for the examples are provided.

[0157] Table 1 Raw Material Information

[0158]

[0159] 2. Equipment

[0160] The main equipment and operating tools include, but are not limited to: vacuum oven, magnetic stirrer, electronic balance, beaker, ultrasonic cleaner, etc.

[0161] Example 1

[0162] This embodiment provides a nickel-plated carbon nanotube thin film, and the specific preparation method is shown below:

[0163] S1. Add 2g of carbon nanotubes and 210g of concentrated nitric acid (68wt%) to a conical flask, insert a condenser into the mouth of the conical flask, place it on an electrically controlled heating platform and heat it to 60°C. Shake the conical flask every half hour for a total of 2 hours to obtain a mixture.

[0164] S2. The mixture obtained in S1 is purified with deionized water and filtered until the filtered water is neutral. Then, the sample is placed in a drying oven at 80°C for 5 hours.

[0165] S3. Disperse 0.5g of carbon nanotubes obtained in S2 in 100g of deionized water and sonicate for 40min to obtain a carbon nanotube suspension;

[0166] S4. Take 59g of concentrated hydrochloric acid (37wt%) and add it to the carbon nanotube suspension obtained in S3 while stirring. Then, stir and dissolve 1g of stannous chloride (SnCl2·2H2O) in the mixture. Stir for 30min to mix evenly, and then sonicate for 60min for sensitization treatment.

[0167] S5. Continue to add 0.02g palladium chloride (PbCl2) and stir until fully dissolved. Then, perform magnetic stirring for 30 minutes to mix thoroughly and ultrasonic oscillation for 60 minutes.

[0168] S6. Wash the carbon nanotubes obtained in S5 with deionized water until the filtered water is neutral to obtain a carbon nanotube dispersion.

[0169] S7. Add different masses (0.31g, 0.62g, 0.93g, 1.25g, 1.55g) of nickel sulfate (98.5wt%) solution (so that the nickel sulfate concentrations are 0.01mol / L, 0.02mol / L, 0.03mol / L, 0.04mol / L, 0.05mol / L, respectively), 2.6g of sodium hypophosphite, 4g of trisodium citrate, and 1.6g of ammonium sulfate to the carbon nanotube dispersion obtained in S6, and magnetically stir for 20min to ensure thorough mixing.

[0170] S8. Add ammonia water to the mixture obtained in S7 to adjust the pH to 11;

[0171] S9. Pour the material obtained in S8 into a three-necked jacketed flask and reflux it under magnetic stirring at 60°C for 50 minutes to obtain a nickel-plated carbon nanotube dispersion.

[0172] S10. The nickel-plated carbon nanotube dispersion was filtered using a polytetrafluoroethylene (PTFE) filter membrane with a pore size of 0.05 μm. Then, the nickel-plated carbon nanotubes obtained by filtration were rinsed three times with deionized water. The nickel-plated carbon nanotubes were then ultrasonically cleaned with deionized water for 50 min. After cleaning, the surface moisture was absorbed with filter paper and placed in a drying oven to dry at 90°C for 5 h to obtain nickel-plated carbon nanotubes.

[0173] S11. Take 2g of nickel-plated carbon nanotubes and 100g of deionized water and add them to a beaker. Sonicate for 35min to obtain a purified nickel-plated carbon nanotube dispersion.

[0174] S12. Place the filter device between the vacuum pump and the receiver, ensuring all connections are sealed; place a 0.22 μm pore size polytetrafluoroethylene (PTFE) filter membrane on the filter plate of the filter device; turn on the vacuum pump to create a negative pressure environment and push the solution through the filter membrane; weigh 50.0 g of the purified nickel-plated carbon nanotube dispersion obtained in S11 and pour it into the filter device, allowing it to pass through the filter membrane under vacuum; filter for 60 min until the dispersion is completely filtered and the membrane is relatively wet, then remove it and place it in a constant temperature drying oven. Dry it at 100℃ for 5 h, then remove the membrane to obtain the nickel-plated carbon nanotube membrane.

[0175] The electromagnetic shielding performance of the prepared nickel-plated carbon nanotube film was tested to determine the optimal nickel sulfate concentration and achieve the best magnetic shielding performance.

[0176] from Figure 6 As can be seen, the nickel-plated carbon nanotube film exhibits the best magnetic shielding performance when the nickel sulfate concentration is 0.04 mol / L. This nickel-plated carbon nanotube film can provide excellent strong electromagnetic shielding protection for complex structures in complex and harsh environments.

[0177] Example 2

[0178] This embodiment provides a nickel-plated carbon nanotube thin film, and the specific preparation method is shown below:

[0179] S1. Add 2g of carbon nanotubes and 210g of concentrated nitric acid (68wt%) to a conical flask, insert a condenser into the mouth of the conical flask, place it on an electrically controlled heating platform and heat it to 60°C, shaking the conical flask every half hour for a total of 2 hours to obtain a mixture;

[0180] S2. Wash the mixture obtained in S1 with deionized water and filter until the filtered water is neutral. Then, place the sample in a drying oven at 80°C for 5 hours.

[0181] S3. Disperse 0.5g of carbon nanotubes obtained in S2 in 100g of deionized water and sonicate for 40min to obtain a carbon nanotube suspension;

[0182] S4. Take 59g of concentrated hydrochloric acid (37wt%) and add it to the carbon nanotube suspension obtained in S3 while stirring. Then, stir and dissolve 1g of stannous chloride (SnCl2·2H2O) in the mixture. Stir for 30min to mix evenly, and then sonicate for 60min for sensitization treatment.

[0183] S5. Continue to add 0.02g palladium chloride (PbCl2) and stir until fully dissolved. Then, perform magnetic stirring for 30 minutes to mix thoroughly and ultrasonic oscillation for 60 minutes.

[0184] S6. Wash the material obtained in S5 with deionized water and filter until the filtered water is neutral to obtain a carbon nanotube dispersion.

[0185] S7. Add 1.25g nickel sulfate, 2.6g sodium hypophosphite, 4g trisodium citrate, and 1.6g ammonium sulfate to the carbon nanotube dispersion obtained in S6, and magnetically stir for 20 minutes to mix thoroughly.

[0186] S8. Add ammonia water to the mixture obtained in S7 to adjust the pH to 8, 9, 10, 11 and 12 respectively;

[0187] S9. Pour the material obtained in S8 into a three-necked jacketed flask and reflux it under magnetic stirring at 60°C for 50 minutes to obtain a nickel-plated carbon nanotube dispersion.

[0188] S10. The nickel-plated carbon nanotube dispersion was filtered using a polytetrafluoroethylene (PTFE) filter membrane with a pore size of 0.05 μm. Then, the nickel-plated carbon nanotubes obtained by filtration were rinsed three times with deionized water. The nickel-plated carbon nanotubes were then ultrasonically cleaned with deionized water for 50 min. After cleaning, the surface moisture was absorbed with filter paper and placed in a drying oven to dry at 90°C for 5 h to obtain nickel-plated carbon nanotubes.

[0189] S11. Take 2g of nickel-plated carbon nanotubes and 100g of deionized water and add them to a beaker. Sonicate for 35min to obtain a purified nickel-plated carbon nanotube dispersion.

[0190] S12. Place the filter device between the vacuum pump and the receiver, ensuring all connections are sealed; place a 0.22μm pore size polytetrafluoroethylene (PTFE) filter membrane on the filter plate of the filter device; turn on the vacuum pump to create a negative pressure environment and push the solution through the filter membrane; weigh 50.0g of the purified nickel-plated carbon nanotube dispersion obtained in S11 and pour it into the filter device, allowing it to pass through the filter membrane under vacuum; filter for 60 minutes until the dispersion is completely filtered and the membrane is relatively wet, then remove it and place it in a constant temperature drying oven. Dry it at 100℃ for 5 hours, then remove the membrane to obtain the nickel-plated carbon nanotube membrane.

[0191] The electromagnetic shielding performance of the prepared nickel-plated carbon nanotube film was tested to determine the optimal nickel sulfate concentration and achieve the best magnetic shielding performance.

[0192] from Figure 7 As can be seen, the nickel-plated carbon nanotube film exhibits the best magnetic shielding performance when the pH of the plating bath is 11. The product morphology is as follows... Figure 3 As shown.

[0193] Example 3

[0194] This embodiment provides a nickel-plated carbon nanotube thin film, and the specific preparation method is shown below:

[0195] S1. Add 2g of carbon nanotubes and 210g of concentrated nitric acid to a conical flask, insert a condenser tube into the mouth of the conical flask, place it on an electrically controlled heating platform and heat it to 50°C, shaking the conical flask every half hour for a total of 2 hours.

[0196] S2. Wash the mixture obtained in S1 with deionized water and filter until the filtered water is neutral. Then, place the sample in a drying oven at 80°C for 5 hours.

[0197] S3. Disperse 0.5g of carbon nanotubes obtained in S2 in 100g of deionized water and sonicate for 40min to obtain a carbon nanotube suspension;

[0198] S4. Take 59g of concentrated hydrochloric acid (37wt%) and add it to the carbon nanotube suspension obtained in S3 while stirring. Then, add 1g of stannous chloride (SnCl2·2H2O) to the mixture while stirring and dissolve it. Stir for 30min to mix evenly, and then sonicate for 60min to perform sensitization treatment.

[0199] S5. Continue to add 0.02g palladium chloride (PbCl2) and stir until fully dissolved. Then, perform magnetic stirring for 30 minutes to mix thoroughly and ultrasonic oscillation for 60 minutes.

[0200] S6. Wash the material obtained in S5 with deionized water and filter until the filtered water is neutral to obtain a carbon nanotube dispersion.

[0201] S7. Add 1.25g nickel sulfate, 2.6g sodium hypophosphite, 4g trisodium citrate, and 1.6g ammonium sulfate to the carbon nanotube dispersion obtained in S6, and magnetically stir for 20 minutes to mix thoroughly.

[0202] S8. Add ammonia water to the mixture obtained in S7 to adjust the pH to 11;

[0203] S9. Pour the material obtained in S8 into a three-necked jacketed flask, and reflux it under magnetic stirring at constant temperatures of 50℃, 55℃, 60℃, 65℃ and 70℃ for 50 min to obtain a nickel-plated carbon nanotube dispersion.

[0204] S10. The nickel-plated carbon nanotube dispersion was filtered using a polytetrafluoroethylene (PTFE) filter membrane with a pore size of 0.05 μm. Then, the nickel-plated carbon nanotubes obtained by filtration were rinsed three times with deionized water. The nickel-plated carbon nanotubes were then ultrasonically cleaned with deionized water for 50 min. After cleaning, the surface moisture was absorbed with filter paper and placed in a drying oven to dry at 90°C for 5 h to obtain nickel-plated carbon nanotubes.

[0205] S11. Take 2g of nickel-plated carbon nanotubes and 100g of deionized water and add them to a beaker. Sonicate for 35min to obtain a purified nickel-plated carbon nanotube dispersion.

[0206] S12. Place the filter device between the vacuum pump and the receiver, ensuring all connections are sealed; place a 0.22 μm pore size polytetrafluoroethylene (PTFE) filter membrane on the filter plate of the filter device; turn on the vacuum pump to create a negative pressure environment and push the solution through the filter membrane; weigh 50.0 g of the purified nickel-plated carbon nanotube dispersion obtained in S11 and pour it into the filter device, allowing it to pass through the filter membrane under vacuum; filter for 60 min until the dispersion is completely filtered and the membrane is relatively wet, then remove it and place it in a constant temperature drying oven. Dry it at 100℃ for 5 h, then remove the membrane to obtain the nickel-plated carbon nanotube membrane.

[0207] The electromagnetic shielding performance of the prepared nickel-plated carbon nanotube film was tested to determine the optimal nickel sulfate concentration and achieve the best magnetic shielding performance.

[0208] from Figure 8 As can be seen, nickel-plated carbon nanotube films exhibit the best magnetic shielding performance when the plating bath temperature is 60℃.

[0209] Example 4

[0210] This embodiment provides a nickel-plated carbon nanotube thin film, and the specific preparation method is shown below:

[0211] S1. Add 2g of carbon nanotubes and 210g of concentrated nitric acid to a conical flask, insert a condenser tube into the mouth of the conical flask, place it on an electrically controlled heating platform and heat it to 50°C, shaking the conical flask every half hour for a total of 2 hours.

[0212] S2. Wash the carbon nanotubes with deionized water and filter until the filtered water is neutral. Place the sample in an oven at 80°C for 5 hours to dry.

[0213] S3. Disperse 0.5g of carbon nanotubes obtained in S2 in 100g of deionized water and sonicate for 40min to obtain a carbon nanotube suspension;

[0214] S4. Take 59g of concentrated hydrochloric acid (37wt%) and add it to the carbon nanotube suspension while stirring. Then, stir and dissolve 1g of stannous chloride (SnCl2·2H2O) in the mixture. Stir for 30min to mix evenly, and then sonicate for 60min for sensitization treatment.

[0215] S5. Continue to add 0.02g palladium chloride (PbCl2) and stir until fully dissolved. Then, perform magnetic stirring for 30 minutes to mix thoroughly and ultrasonic oscillation for 60 minutes.

[0216] S6. Wash the carbon nanotubes obtained in S5 with deionized water until the filtered water is neutral to obtain a carbon nanotube dispersion.

[0217] S7. Add 1.25g nickel sulfate, 2.6g sodium hypophosphite, 4g trisodium citrate, and 1.6g ammonium sulfate solution to the carbon nanotube dispersion obtained in S6, and magnetically stir for 20 minutes to ensure thorough mixing;

[0218] S8. Add ammonia water to the mixture obtained in S7 to adjust the pH to 11.

[0219] S9. Pour the material obtained in S8 into a three-necked jacketed flask and reflux it under magnetic stirring at 60°C for 50 minutes to obtain a nickel-plated carbon nanotube dispersion.

[0220] S10. The nickel-plated carbon nanotube dispersion was filtered using a polytetrafluoroethylene (PTFE) filter membrane with a pore size of 0.05 μm. Then, the nickel-plated carbon nanotubes obtained by filtration were rinsed three times with deionized water. The nickel-plated carbon nanotubes were then ultrasonically cleaned with deionized water for 50 min. After cleaning, the surface moisture was absorbed with filter paper and placed in a drying oven to dry at 90°C for 5 h to obtain nickel-plated carbon nanotubes.

[0221] S11. Take 2g of nickel-plated carbon nanotubes and 100g of deionized water and add them to a beaker. Sonicate for 35min to obtain a purified nickel-plated carbon nanotube dispersion.

[0222] S12. Place the filter device between the vacuum pump and the receiver, ensuring all connections are sealed; place polytetrafluoroethylene (PTFE) filter membranes with pore sizes of 0.1μm, 0.22μm, 0.45μm, 0.65μm, and 0.8μm respectively on the filter plate of the filter device; turn on the vacuum pump to create a negative pressure environment and push the solution through the filter membrane; weigh 50.0g of the purified nickel-plated carbon nanotube dispersion obtained in S11 and pour it into the filter device, allowing it to pass through the filter membrane under vacuum; filter for 60 minutes until the dispersion is completely filtered and the membrane is relatively wet, then remove it and place it in a constant temperature drying oven. Dry it at 100℃ for 5 hours, then remove the membrane to obtain the nickel-plated carbon nanotube membrane;

[0223] The electromagnetic shielding performance of the prepared nickel-plated carbon nanotube film was tested to determine the optimal pore size of the filter membrane and to achieve the best magnetic shielding performance.

[0224] from Figure 9 As can be seen, when the filter membrane pore size is 0.22 μm, the nickel-plated carbon nanotube film has the best magnetic shielding performance.

[0225] Performance testing:

[0226] 1. Bending resistance test: The nickel-plated carbon nanotube film prepared in Example 1 was subjected to a bending resistance test. After being folded repeatedly for 500 times, its surface did not crack or break, maintaining the integrity of its shape and structure. Moreover, its electrical conductivity was still above 1.6×10⁵ S / m, with basically no decrease.

[0227] 2. Areal density test: The nickel-plated carbon nanotube film prepared in Example 1 was measured with an analytical balance and a micrometer to measure the mass and thickness of the film. The areal density was found to be 0.0285±0.001kg / m2 and the thickness was 1.44±0.2mm.

[0228] 3. Conductivity Test: The conductivity of the nickel-plated carbon nanotube film prepared in Example 1 was measured multiple times using a four-needle detector. The average value was calculated and corrected, resulting in a conductivity of 176959.83 S / m. Figure 4 As shown.

[0229] 4. Corrosion resistance: The nickel-plated carbon nanotube film prepared in Example 1 was subjected to an acetic acid salt spray test in a salt spray chamber according to GB_T 10125-2021. The mass loss after 24 hours was between 3 g / m2 and 4 g / m2. After 240 hours, it could still maintain an average electromagnetic shielding performance of more than 25 dB.

[0230] 5. Resistance to damp heat: The nickel-plated carbon nanotube film prepared in Example 1 was subjected to a high-temperature and high-humidity environmental test using a damp heat environment test chamber according to GB_T 1740-2007. After 96 hours, the film showed a rust level of 1, a blistering level of 2, slight discoloration, and level 1 cracking. At this point, it still exhibited an average electromagnetic protection performance of 20 dB.

[0231] 6. Electromagnetic shielding effectiveness test:

[0232] The electromagnetic shielding effectiveness of the nickel-plated carbon nanotube film prepared in Example 1 was tested, and the results are as follows: Figure 5 As shown, it has good electric field shielding and magnetic field shielding performance.

[0233] The magnetic shielding effectiveness of the nickel-plated carbon nanotube films prepared in Examples 1-4 was tested, and the results are as follows: Figures 6-9 As shown.

[0234] In summary, to achieve good protection against complex electromagnetic environments, especially strong electromagnetic pulses, for some devices (such as aircraft and shipboard internal electronic equipment), this application embodiment uses a nickel plating solution containing divalent nickel salts, complexing agents, reducing agents, buffers, and pH adjusters to plate carbon nanotubes with nickel, and then prepares a thin film structure through vacuum filtration. This thin film possesses good electric and magnetic field shielding effectiveness, good bending resistance, and uniform texture. While achieving weight reduction, it can also adhere well to complex structural surfaces, making it applicable to strong electromagnetic pulse protection for complex structural shapes in harsh environments. Specifically, it has the following excellent technical effects:

[0235] 1. It has good electric field shielding and magnetic field shielding performance, and can maintain a shielding effectiveness of more than 40dB in a wide frequency range of 2MHz to 40GHz.

[0236] 2. It has good bending resistance. It can maintain the integrity of its shape and structure even after being bent more than 500 times. Its electrical conductivity remains basically unchanged, and it can fit well into complex structural surfaces.

[0237] 3. The texture is uniform, with a surface density of 0.02kg / m2~0.03kg / m2, which helps to reduce the weight of the protective composite film, achieve lightweight color traces, and is more conducive to improving adhesion.

[0238] 4. It has good resistance to environmental corrosion and is suitable for environments with high humidity and salt spray.

[0239] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An electromagnetic protection composite film, characterized in that, The electromagnetic shielding composite membrane is obtained by vacuum filtration of purified nickel-plated carbon nanotube dispersion. The filter membrane used in the vacuum filtration has a pore size of 0.1~0.8μm, and the areal density of the electromagnetic shielding composite membrane is 0.02~0.03 kg / m². The electromagnetic shielding composite membrane has an electric field and magnetic field shielding effectiveness of not less than 40 dB in the frequency range of 20 MHz to 40 GHz. The purified nickel-plated carbon nanotube dispersion is prepared from nickel-plated carbon nanotubes, and the preparation method of the nickel-plated carbon nanotubes includes: Provide carbon nanotubes; The carbon nanotubes were chemically nickel-plated using a nickel plating solution to prepare a nickel-plated carbon nanotube dispersion. The nickel plating solution consisted of divalent nickel salt, complexing agent, reducing agent, buffer, and pH adjuster. The nickel-plated carbon nanotube dispersion was subjected to solid-liquid separation to obtain nickel-plated carbon nanotubes. In the nickel plating solution, the concentration of the divalent nickel salt is 0.03 mol / L to 0.05 mol / L; the pH of the nickel plating solution is 10 to 12. The concentration of the complexing agent is 0.05 mol / L to 0.1 mol / L; The concentration of the reducing agent is 0.13 mol / L to 0.20 mol / L; The concentration of the buffer is 0.05 mol / L to 0.1 mol / L.

2. The electromagnetic protection composite film as described in claim 1, characterized in that, The nickel plating solution has at least one of the following characteristics (4) to (6): (4) The divalent nickel salt includes at least one of nickel sulfate and nickel chloride; (5) The complexing agent includes at least one of trisodium citrate, ethylenediaminetetraacetic acid, monosodium citrate and disodium citrate; (6) The reducing agent includes sodium hypophosphite.

3. The electromagnetic protection composite film as described in claim 1, characterized in that, The electroless nickel plating process includes: mixing the nickel plating solution and the carbon nanotubes and then plating them at a temperature of 50 ℃ to 70 ℃.

4. The electromagnetic protection composite film according to any one of claims 1 to 3, characterized in that, Before performing electroless nickel plating on the carbon nanotubes using a nickel plating solution, the process further includes: The carbon nanotubes were subjected to oxidation purification, sensitization and activation treatments in sequence.

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