Carbon fiber / magnetic carbon nanotube composite material and preparation method and application thereof

Abstract

The present application aims at solving the problems of single loss mechanism, poor impedance matching and easy aggregation of carbon fibers in the secondary composite process of the current carbon fiber wave-absorbing material. The present application relates to a preparation method of carbon / carbon composite material composed of magnetic carbon nanotubes grown in situ on the surface of carbon fibers and application thereof. The method is simple in operation and the obtained composite material has good wave-absorbing performance. The method comprises the following steps: step I: cleaning the carbon fibers; step II: growing nickel-iron hydroxide nanosheets in situ on the surface of the carbon fibers in step I through a hydrothermal reaction; and step III: obtaining carbon fiber / magnetic carbon nanotube composite material by high-temperature annealing treatment of the carbon fiber / nickel-iron hydroxide obtained in step II with the assistance of melamine. The radial growth of carbon nanotubes on the surface of carbon fibers increases the specific surface area of the material and prolongs the electron transmission path, which is beneficial to electromagnetic wave loss.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wave-absorbing materials, and relates to a carbon fiber / magnetic carbon nanotube composite wave-absorbing material and a carbon fiber-based wave-absorbing material. BACKGROUND

[0002] With the development of science and technology and the rapid development of communication technology, especially the advent of the 5G era, the transmission of electromagnetic signals is becoming more and more convenient and diversified. Whether it is military use or industrial production needs, a large number of electromagnetic communication is indispensable. While providing convenience for people, a large amount of unnecessary electromagnetic wave leakage has become a kind of pollution that interferes with the normal operation of artificial devices and human activities. Space electromagnetic waves can affect wireless communication and the normal operation of various electromagnetic devices. For example, flight delays caused by electromagnetic wave interference, electronic instrument test errors, signal interference of communication tools, etc. On the other hand, in modern reconnaissance guidance systems, radar is still the most important means. The use of radar wave-absorbing material technology can reduce the radar wave reflection intensity of military equipment such as aircraft and submarine, and improve the stealth penetration capability of weapon equipment. Therefore, wave-absorbing materials have played a huge application potential in the fields of electromagnetic compatibility, electromagnetic radiation protection and microwave stealth technology.

[0003] Traditional metal-based magnetic materials, such as ferrite and metal powder, have strong magnetism, large magnetic loss, low cost, and strong wave-absorbing ability at certain special frequencies. However, their high density, easy agglomeration, narrow wave-absorbing frequency band and poor weather resistance limit the application of ferromagnetic materials as high-performance wave-absorbing materials. New carbon materials such as graphene, carbon nanotubes, mesoporous carbon and carbon fibers have broad application prospects in the field of microwave absorption due to their excellent dielectric properties, good composite properties, special microstructure, low specific gravity, strong chemical stability, and the advantages of convenient use and simple maintenance. They have gradually become the focus of research and application in the academic and industrial circles. Among them, carbon fiber wave-absorbing materials have unique shape anisotropy and mechanical properties, providing a truly replaceable metal as a structural material for main load-bearing components, and are a kind of wave-absorbing material with great development prospects. However, the single component morphology of carbon fiber has low resistivity, which leads to poor impedance matching characteristics, and it is a strong reflector of microwaves, suitable for use as a conductive reflective material and a reinforcing body rather than an absorber. Therefore, in order to obtain more efficient microwave-absorbing carbon fiber materials, special treatment is required, including surface treatment, compounding with other wave-absorbing materials or microstructure design. Using one-dimensional carbon fiber as a template, special hierarchical structure magnetic carbon nanotubes are grown in situ to obtain carbon fiber / magnetic carbon nanotube composites. The research significance lies in optimizing the preparation parameters, maintaining the stable hierarchical radial structure, increasing the specific surface area of carbon fiber and increasing the electron transmission loss path to realize efficient absorption of electromagnetic waves. SUMMARY

[0004] The present application aims to solve the problems of single loss mechanism, poor impedance matching and easy agglomeration of carbon fibers in the secondary compounding process of the current carbon fiber wave-absorbing material, and provides a carbon fiber-based composite wave-absorbing material and a preparation method thereof.

[0005] One is a wave-absorbing material made of carbon fibers as a matrix and magnetic carbon nanotubes grown in situ.

[0006] The preparation method of the carbon fiber-based composite material with magnetic carbon nanotubes grown in situ is specifically performed according to the following steps:

[0007] I. The carbon fibers are immersed in a mixed solution of Ni(NO3)2·6H2O, FeSO4·7H2O, NH4F and urea for 30 min, and then the solution is transferred to a stainless steel high-pressure reaction kettle for reaction. The temperature is controlled at 100-120 DEG C, and the reaction time is 8-10 h. After drying, a carbon fiber / nickel-iron hydroxide composite material is obtained;

[0008] II. The carbon fiber / nickel-iron hydroxide composite material obtained in step I is subjected to melamine-assisted annealing treatment, and the annealing temperature is controlled at 700-900 DEG C, and the annealing time is 2-4 h to obtain the carbon fiber-based composite wave-absorbing material with magnetic carbon nanotubes grown in situ.

[0009] In the present application, the carbon fiber and magnetic carbon nanotube composite material are used as the wave-absorbing material. The magnetic carbon nanotubes on the surface of the carbon fibers can increase the specific surface area of the composite material, prolong the electron transfer path and improve the wave-absorbing performance of the composite material.

[0010] The present application has the following advantages:

[0011] I. The mutual connection between the magnetic carbon nanotubes forms a three-dimensional network structure, which is beneficial to the multiple refraction and scattering of electromagnetic waves;

[0012] II. The magnetic carbon nanotubes prolong the path of induced current transmission and increase the electromagnetic wave attenuation capacity;

[0013] III. A large number of heterogeneous interfaces can induce the interface polarization of the composite material, which is helpful for the loss of electromagnetic waves.

[0014] The present application is used for preparing the carbon fiber-based wave-absorbing material. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0016] Figure 1 XRD pattern of the carbon fiber / magnetic carbon nanotube composite wave-absorbing material prepared for Example 1;

[0017] Figure 2 SEM pattern of the carbon fiber / magnetic carbon nanotube composite wave-absorbing material prepared for Example 2;

[0018] Figure 3 Wave-absorbing performance pattern of the carbon fiber / magnetic carbon nanotube composite wave-absorbing material prepared for Example 3.

[0019] The beneficial effects of the present application are verified by the following examples. DETAILED DESCRIPTION

[0020] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0021] In order to improve the microwave absorbing performance of the carbon fiber, it can be compounded with other wave-absorbing materials to fully utilize the synergistic effect of multiple components to improve the impedance matching characteristics of the composite material.

[0022] In the embodiments of the present application, on one hand, multi-stage magnetic carbon nanotubes are constructed on the surface of the carbon fiber, such as Figures 1-3 It can be known that the magnetic carbon nanotubes grow radially on the surface of the carbon fiber. Moreover, the metal nickel-iron alloy has a certain magnetism and can provide a certain magnetic loss to complement the dielectric loss of the carbon fiber, thereby greatly improving the microwave absorbing performance of the composite material. On the other hand, the embodiments of the present application also provide a preparation method of the above-mentioned carbon fiber / magnetic carbon nanotube composite material, including the following steps:

[0023] I. Carbon fiber cleaning; 1 g of carbon fiber is respectively placed into acetone, hydrochloric acid (3 M), anhydrous ethanol and deionized water, and each is ultrasonically treated for 10-30 min in sequence, so as to remove the oxides and impurities on the surface thereof;

[0024] II. Preparation of carbon fiber / nickel-iron hydroxide composite; 0.05 g of carbon fiber, 0.73 g of Ni(NO3)2·6H2O, 0.17 g of FeSO4·7H2O, 0.46 g of NH4F, and 1.85 g of urea were added into 30 mL of deionized water and stirred for 10 min. Then, the cleaned carbon fiber was immersed in the solution for 30 min, and then the solution was transferred to a high-pressure reaction kettle for reaction. After the reaction kettle was naturally cooled to room temperature, the product was washed several times with deionized water and ethanol, and vacuum dried at 50 ℃ for 12 h. After cooling, it was ready for use;

[0025] III. Preparation of carbon fiber / magnetic carbon nanotube composite: a certain mass of carbon fiber / nickel-iron hydroxide was placed in a square porcelain boat and placed downstream of a tube furnace, and a certain mass of melamine was placed upstream. The program was set to 2 ℃ / min from room temperature to 800 ℃, and the target temperature was maintained for 2 h. After the tube furnace was naturally cooled to room temperature, a carbon fiber / magnetic carbon nanotube composite material was obtained.

[0026] In the specific implementation process, in step one, the carbon fiber is cleaned to remove organic matter and oxides and other impurities on the surface of the carbon fiber. In step two, the drying process can be selected by those skilled in the art according to the needs, and the preferred drying process is vacuum drying.

[0027] In the embodiment of the present application, carbon fiber is used as the substrate, carbon fiber / nickel-iron hydroxide is synthesized by a hydrothermal method, and then a carbon fiber / magnetic carbon nanotube composite material is prepared by a melamine-assisted high-temperature annealing method. The raw materials, equipment and process used in the embodiment of the present application are simple, low in cost, easy and safe to operate, non-toxic and harmless, clean and environmentally friendly.

[0028] Specific implementation method one: the carbon fiber / magnetic carbon nanotube composite wave-absorbing material of the present embodiment is prepared by using carbon fiber as the substrate and growing magnetic carbon nanotubes on the surface of the substrate in situ.

[0029] Specific implementation method two: the method for preparing the carbon fiber / magnetic carbon nanotube wave-absorbing material described in specific implementation method one is performed according to the following steps:

[0030] I. Carbon fiber cleaning: 1 g of carbon fiber was placed in acetone, hydrochloric acid (3 M), anhydrous ethanol and deionized water, respectively, and was ultrasonically treated for 10-30 min in each solvent to remove oxides and impurities on the surface of the carbon fiber;

[0031] II. Preparation of carbon fiber / nickel hydroxide sample: carbon fiber / nickel-iron hydroxide composite material was prepared; 0.05 g of carbon fiber, 0.73 g of Ni(NO3)2·6H2O, 0.17 g of FeSO4·7H2O, 0.46 g of NH4F, and 1.85 g of urea were added to 30 mL of deionized water and stirred for 10 min, then 0.05 g of cleaned carbon fiber was immersed in the solution for 30 min, and then the solution was transferred to a high-pressure reaction kettle for hydrothermal reaction at 90°C for 9 h. After the reaction kettle was naturally cooled to room temperature, the product was washed several times with deionized water and ethanol, and vacuum dried at 50°C for 12 h;

[0032] III. Melamine-assisted annealing treatment was performed on the carbon fiber / nickel-iron hydroxide composite material obtained in step I, the annealing temperature was controlled at 800°C, and the annealing time was 2 h, to obtain a carbon fiber-based composite wave-absorbing material with in-situ grown magnetic carbon nanotubes.

[0033] Specific embodiment III: The difference between this embodiment and specific embodiment II is that the mass ratio of melamine to carbon fiber / nickel-iron hydroxide in step II is adjusted to 1:5, 1:10, and 1:15, and the rest is the same as specific embodiment II.

[0034] Example I

[0035] (1) Carbon fiber cleaning: 1 g of carbon fiber was sequentially placed in 50 ml of acetone, 50 ml of hydrochloric acid (3M), 50 ml of anhydrous ethanol, and 50 ml of deionized water for ultrasonic cleaning for 30 min to remove the oxides and impurities on the surface of the carbon fiber;

[0036] (2) Preparation of carbon fiber / nickel-iron hydroxide: 0.73 g of Ni(NO3)2·6H2O, 0.17 g of FeSO4·7H2O, 0.46 g of NH4F, and 1.85 g of urea were added to 30 mL of deionized water and stirred for 10 min. Then 0.05 g of cleaned carbon fiber was immersed in the solution for 30 min, and then the solution was transferred to a high-pressure reaction kettle for hydrothermal reaction at 90°C for 9 h. After the reaction kettle was naturally cooled to room temperature, the product was washed several times with deionized water and ethanol, and vacuum dried at 60°C for 12 h;

[0037] (3) Preparation of carbon fiber / magnetic carbon nanotube composite material: the carbon fiber / nickel-iron hydroxide prepared in step II above was placed in a square porcelain boat and placed downstream of a tube furnace, and 10 times the weight of melamine based on the carbon fiber / nickel-iron hydroxide was placed in the porcelain boat and placed upstream of the tube furnace. Set the program to 2°C / min from room temperature to 800°C and hold for 2 h. After the tube furnace was naturally cooled to room temperature, a carbon fiber / magnetic carbon nanotube composite material (referred to as sample 1) was obtained.

[0038] Example II

[0039] (1) Carbon fiber cleaning: 1 g of carbon fiber was sequentially placed into 50 ml of acetone, 50 ml of hydrochloric acid (3 M), 50 ml of anhydrous ethanol, and 50 ml of deionized water for ultrasonic cleaning for 30 min to remove the oxides and impurities on the surface thereof;

[0040] (2) Preparation of carbon fiber / nickel-iron hydroxide: 0.73 g of Ni(N03)2-6H20, 0.17 g of FeS04-7H20, 0.46 g of NH4F, and 1.85 g of urea were added to 30 mL of deionized water and stirred for 10 min. Then, 0.05 g of the cleaned carbon fiber was immersed in the solution for 30 min, and then the solution was transferred to a high-pressure reaction kettle for hydrothermal reaction at 90°C for 9 h. After the reaction kettle was naturally cooled to room temperature, the product was washed several times with deionized water and ethanol, and vacuum dried at 60°C for 12 h;

[0041] (3) Preparation of carbon fiber / magnetic carbon nanotube composite material: the carbon fiber / nickel-iron hydroxide prepared in step two was placed in a square porcelain boat and placed downstream of a tube furnace, and 15 times the weight of melamine based on the carbon fiber / nickel-iron hydroxide was placed in the porcelain boat and placed upstream of the tube furnace. Set program 2°C / min from room temperature to 800°C and keep for 2h, after the tube furnace is naturally cooled to room temperature, the carbon fiber / magnetic carbon nanotube composite material (recorded as sample 2) is obtained.

[0042] Example Three

[0043] (1) Carbon fiber cleaning: 1 g of carbon fiber was sequentially placed into 50 ml of acetone, 50 ml of hydrochloric acid (3 M), 50 ml of anhydrous ethanol, and 50 ml of deionized water for ultrasonic cleaning for 30 min to remove the oxides and impurities on the surface thereof;

[0044] (2) Preparation of carbon fiber / nickel-iron hydroxide: 0.73 g of Ni(N03)2-6H20, 0.17 g of FeS04-7H20, 0.46 g of NH4F, and 1.85 g of urea were added to 30 mL of deionized water and stirred for 10 min. Then, 0.05 g of the cleaned carbon fiber was immersed in the solution for 30 min, and then the solution was transferred to a high-pressure reaction kettle for hydrothermal reaction at 90°C for 9 h. After the reaction kettle was naturally cooled to room temperature, the product was washed several times with deionized water and ethanol, and vacuum dried at 60°C for 12 h;

[0045] (3) Preparation of carbon fiber / magnetic carbon nanotube composite: the carbon fiber / nickel-iron hydroxide prepared in the above step two is placed in a square porcelain boat and placed downstream of the tube furnace, and 20 times the weight of melamine on the carbon fiber / nickel-iron hydroxide is placed in the porcelain boat and placed upstream of the tube furnace. Set program 2℃ / min from room temperature to 800℃ and keep for 2h, after the tube furnace is naturally cooled to room temperature, carbon fiber / magnetic carbon nanotube composite (denoted as sample 3) is obtained.

[0046] The phase of the obtained carbon fiber / magnetic carbon nanotube is shown in Figure 1 It can be seen from the XRD pattern that the composite is composed of carbon and nickel-iron alloy. The micro-morphology of the obtained carbon fiber / magnetic carbon nanotube is shown in Figure 2 It can be seen that the surface of the carbon fiber is composed of interconnected nanotubes.

[0047] Preparation of carbon fiber / magnetic carbon nanotube and paraffin composite

[0048] According to the mass ratio, 3wt% of carbon fiber / magnetic carbon nanotube and 97wt% of paraffin are weighed and placed in a 30ml crucible and placed in an 80℃ oven for 10min or so to completely melt the paraffin. Take out the crucible and stir well. After the paraffin solidifies, the sample is placed in a self-made stainless steel mold to prepare a sample with an inner diameter of 3.04mm and an outer diameter of 7mm. After polishing with different types of sandpaper, a 2mm concentric ring sample is finally prepared.

[0049] The electromagnetic parameters of the sample in the frequency range of 2-18 GHz are tested by using a vector network analyzer, and simulation calculation is carried out according to the transmission line theory.

[0050] The simulation results are shown in Figure 2 The results show that the carbon fiber / magnetic carbon nanotube composite has a maximum reflection loss of-25.8dB at a frequency of 9.52GHz under a thickness of 2.5mm, and the maximum effective absorption (reflection loss less than-10dB) frequency bandwidth can reach 7.28GHz (10.72-18GHz) under a single thickness (1.95mm) effective absorption bandwidth.

[0051] It should be understood that those skilled in the art can make improvements or changes according to the above description, and all these improvements and changes shall belong to the protection scope of the appended claims of the present application.

Claims

1. A method for producing a carbon fiber / magnetic carbon nanotube composite material, characterized by, The method comprises the following steps: A) carbon fiber cleaning; B) preparing carbon fiber / nickel-iron hydroxide composite material by growing nickel-iron hydroxide nanosheet on the surface of carbon fiber in situ through hydrothermal reaction; C) preparing carbon fiber / magnetic carbon nanotube composite material by subjecting the carbon fiber / nickel-iron hydroxide composite material obtained in the above step to melamine-assisted high-temperature annealing treatment; The carbon fiber / nickel-iron hydroxide composite material is obtained through hydrothermal treatment of a reaction kettle; The mass of the carbon fiber is 0.05 g, the mass of nickel nitrate hexahydrate is 0.73 g, the mass of ferrous sulfate heptahydrate is 0.17 g, the mass of ammonium fluoride is 0.46 g, and the mass of urea is 1.85 g; The capacity of the reaction kettle is 50 ml; The temperature of the hydrothermal reaction is 100-120 ℃; The time of the hydrothermal reaction is 8-10 h.

2. The production method according to claim 1, characterized by, The carbon fiber is obtained by sequentially placing the carbon fiber in acetone, hydrochloric acid, anhydrous ethanol and deionized water; The acetone, hydrochloric acid, anhydrous ethanol and deionized water are each 50-100 ml; The concentration of the hydrochloric acid is 3 M.

3. The preparation method according to claim 1, characterized in that, The carbon fiber / magnetic carbon nanotube composite material is obtained by high-temperature annealing treatment of the carbon fiber / nickel-iron hydroxide composite material with the assistance of melamine; The high-temperature annealing temperature is 700-900 ℃; The annealing time is 2-4 h; The amount of melamine is 5-20 times the mass of the carbon fiber / nickel-iron hydroxide.

4. A wave-absorbing material, characterized by, The carbon fiber / magnetic carbon nanotube composite material is prepared by the preparation method of any one of claims 1-3.

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