CN113613479B - Microwave absorbing material for assembling microtubes by core-shell spindle array and preparation and application thereof - Google Patents

Microwave absorbing material for assembling microtubes by core-shell spindle array and preparation and application thereof Download PDF

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CN113613479B
CN113613479B CN202110805533.7A CN202110805533A CN113613479B CN 113613479 B CN113613479 B CN 113613479B CN 202110805533 A CN202110805533 A CN 202110805533A CN 113613479 B CN113613479 B CN 113613479B
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molybdenum trioxide
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CN113613479A (en
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车仁超
许春洋
张捷
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Fudan University
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Abstract

The invention relates to a microwave absorbing material of a micron tube assembled by a core-shell spindle array, a preparation method and an application thereof 3 O 4 ) The outer shell layer is a carbon layer, and the whole material is a micron tube. The spindle array assembled microtube material of the present invention exhibits excellent electromagnetic wave loss capability in the frequency range of 2.0-18.0 GHz. According to the invention, molybdenum trioxide is used as a template, a hydroxyl ferric oxide array grows on the surface of the molybdenum trioxide, then polydopamine is coated on the surface of the molybdenum trioxide, and a micrometer tube material assembled by core-shell spindle body arrays with different magnetic particles can be prepared by changing the calcining temperature. The invention has simple synthesis process and excellent material performance, and has wide application prospect in the field of microwave absorption.

Description

Microwave absorbing material for assembling microtubes by core-shell spindle array and preparation and application thereof
Technical Field
The invention belongs to the technical field of functional material preparation, and relates to a microwave absorbing material for a micron tube assembled by a core-shell spindle array, and preparation and application thereof.
Background
In the present society, various electronic and electric products are widely applied, and the problem of electromagnetic pollution is increasingly serious, so that the design and synthesis of effective radiation-proof materials are urgent. The electromagnetic absorption material is a functional material which consumes electromagnetic waves and essentially absorbs and converts the electromagnetic waves into heat energy or other forms of energy so as to weaken the action of the electromagnetic waves. Carbon materials have been regarded as good microwave absorbing materials, including carbon fibers, carbon nanotubes, graphene and the like, and have the characteristics of light weight, good chemical stability, strong dielectric loss and the like. However, as with other single component microwave absorbing materials, the microwave absorbing properties of carbon materials are severely limited due to their lack of magnetic loss capability and poor characteristic impedance. At present, two methods are adopted to solve and improve the wave absorbing performance of the carbon material. One method is to compound a carbon material with a magnetic material (e.g., metallic iron, cobalt, nickel) to improve the magnetic loss capability of the material and thus the impedance matching capability. The other method is to reasonably design the structure of the material, such as a porous structure, a tubular structure, a core-shell structure and the like, to form a heterogeneous interface so as to improve polarization loss and form a cavity to scatter microwaves.
In recent years, structural designs of magnetic carbon materials have been receiving attention from many researchers, particularly magnetic iron-based carbon materials. Iron-based materials such as iron and ferroferric oxide have excellent magnetic loss capacity; after the composite material is compounded with the carbon material, the iron-based carbon material can overcome the defects of low dielectric loss, poor impedance matching and the like, and effectively improves the wave-absorbing performance of the composite material. In addition, by utilizing the structural advantages, the microwave absorbing material with a one-dimensional structure is designed, and the dielectric loss capacity is effectively improved due to higher anisotropy. However, most of the reported one-dimensional wave-absorbing materials are formed by tightly packing magnetic particles on a carbon material. The accumulation of magnetic material reduces the magnetic coupling effect and does not produce strong magnetic loss. And the smaller gaps between the composite materials also result in more severe impedance. To solve these problems, we should consider both the dispersion of the magnetic component and the void problem when designing the structure of the material. Numerous studies show that the material with the hierarchical structure can fully utilize the advantages of the materials of all components and effectively exert the maximum performance of the material. Therefore, the requirement of the material in the microwave absorption direction can be effectively met by reasonably designing the one-dimensional hierarchical structure.
Disclosure of Invention
The invention aims to provide a microwave absorbing material for assembling a micron tube by a core-shell spindle array, and preparation and application thereof, and the microwave absorbing material is simple in synthesis process, excellent in performance and the like.
According to the invention, researches show that the agglomeration phenomenon of the magnetic material is more serious after high-temperature calcination because the magnetic component is easy to agglomerate; in addition, after being compounded with a carbon material, the magnetic properties of the original material are inevitably weakened by introducing a nonmagnetic component. Based on the problems, a high-density spindle array assembled microtube structure is designed, and after calcination in a hydrogen argon atmosphere, iron-based carbon materials with different magnetic components can be obtained. Due to the core-shell structure and the tubular structure of the material, the problem of agglomeration of the magnetic material is effectively solved; meanwhile, the magnetic spindle body array with high density can effectively improve the overall magnetism of the material. The components of the magnetic material and the carbon material, and the structural advantages of the core shell and the micron tube promote the magnetic loss and the dielectric loss of the composite material, and enhance the wave absorbing capability of the micron tube composite material assembled by the iron-ferroferric oxide nano spindle array coated by the carbon layer.
The invention adopts a simple reflux and room temperature polymerization reaction method to synthesize the polydopamine-coated ferric hydroxide array-assembled microtubes. After calcination in hydrogen and argon atmosphere, the product structure can be well maintained, and no obvious agglomeration phenomenon occurs. Meanwhile, the microwave absorbing material of the micron tube assembled by the core-shell spindle array shows excellent comprehensive performance in the microwave absorbing field.
The purpose of the invention can be realized by the following technical scheme:
one of the technical schemes of the invention provides a preparation method of a microwave absorbing material of a micron tube assembled by a core-shell spindle array, which comprises the following steps:
(1) Weighing ammonium molybdate tetrahydrate, dispersing the ammonium molybdate tetrahydrate in deionized water, adding a concentrated nitric acid solution, stirring, reacting, separating and drying to obtain molybdenum trioxide nanorods;
(2) Dispersing the molybdenum trioxide nanorods in deionized water, adding ferric trichloride, performing ultrasonic treatment, performing heating reflux reaction, separating and drying the obtained reaction product to obtain the molybdenum trioxide nanorods coated with the iron oxyhydroxide arrays;
(3) Weighing molybdenum trioxide nanorods coated by a ferric hydroxide array, dispersing the molybdenum trioxide nanorods into deionized water, adding tris (hydroxymethyl) aminomethane, performing ultrasonic stirring to obtain a solution A, continuously adding dopamine hydrochloride, performing stirring reaction, separating, cleaning and drying the obtained product to obtain a polydopamine-coated ferric hydroxide array-assembled microtube;
(4) And (3) placing the microtube assembled by the poly-dopamine-coated iron oxyhydroxide array under the protection of hydrogen and argon gas, and calcining to obtain a target product.
Further, in the step (1), the adding amount ratio of ammonium molybdate tetrahydrate, concentrated nitric acid solution and deionized water is (0.4-0.6) g: (20 to 40) mL: (2-3) mL, wherein the mass fraction of the concentrated nitric acid solution is 65-68%, and optionally 68%.
Further, in the step (1), the reaction temperature is 160-200 ℃ and the reaction time is 10-14 h.
Further, in the step (2), the adding amount ratio of the molybdenum trioxide micron rods to the ferric trichloride is (25-36) mg: (1.5-2.1) g.
Further, in the step (2), the temperature of the heating reflux reaction is 60-100 ℃, optionally 80 ℃, and the time is 4-6 hours, optionally 5 hours.
Further, in the step (3), the molybdenum trioxide core-shell micron rods coated with the iron oxyhydroxide array, the mass ratio of the tris (hydroxymethyl) aminomethane to the dopamine hydrochloride is (45-76): (110 to 135): (110 to 135).
Further, in the step (3), the stirring reaction time is 1-3 h.
Further, in the step (4), the calcining temperature is 400-600 ℃, optionally 500 ℃, and the time is 3-5 h, optionally 4h.
The second technical scheme of the invention provides a microwave absorbing material of a micron tube assembled by a core-shell spindle array, which is prepared by the preparation method.
The third technical scheme of the invention provides an application of a microwave absorbing material of a micron tube assembled by a core-shell spindle array in the field of microwave absorption.
Compared with the prior art, the invention has the following advantages:
(1) The micron tube material provided by the invention is applied to the field of microwave absorption and has the advantage of high reflection loss. Microtubes (Fe-Fe) assembled in spindle array with iron-ferroferric oxide particles as inner core 3 O 4 @ C-500) can reach-46.1 dB of maximum reflection loss.
(2) The synthesis method is novel, and the micron tube material assembled by the core-shell spindle body array of the carbon-coated magnetic particles is successfully synthesized.
(3) The preparation method provided by the invention has the advantages of simple synthesis process, convenient regulation and control of characteristics such as spindle arrays, core-shell structures and the like, and mass production.
(4) The inner core magnetic component of the core-shell spindle array is convenient to regulate and control, so that the microwave absorption performance of the material can be conveniently regulated.
Drawings
FIG. 1 is a flow chart of the synthesis of carbon coated core-shell spindle array assembled microtube material of different magnetic components.
FIG. 2 is a scanning electron micrograph of each sample: (a1) And (a 2) micron tube Fe assembled by carbon-coated ferroferric oxide core-shell spindle array 3 O 4 @ C-400; (b1) And (b 2) micron tube Fe-Fe assembled by carbon-coated iron-ferroferric oxide core-shell spindle array 3 O 4 @ C-500; (c1) And (c 2) micron tubes assembled by carbon-coated iron core-shell spindle arrays Fe @ C-600.
FIG. 3 is a transmission electron micrograph of each sample: (a) Micron tube Fe assembled by carbon-coated ferroferric oxide core-shell spindle array 3 O 4 @ C-400; (b) Micron tube Fe-Fe assembled by carbon-coated iron-ferroferric oxide core-shell spindle array 3 O 4 @ C-500; (c) The micron tube assembled by the carbon-coated iron core-shell spindle array is Fe @ C-600.
FIG. 4 is an X-ray diffraction spectrum of microtube material assembled with a core-shell spindle array.
Fig. 5 shows the values of the reflection loss for different thicknesses of the samples: (a) Micron tube Fe assembled by carbon-coated ferroferric oxide core-shell spindle array 3 O 4 @ C-400; (b) Micron tube Fe-Fe assembled by carbon-coated iron-ferroferric oxide core-shell spindle array 3 O 4 @ C-500; (c) Micron tube Fe @ C-600 assembled by carbon-coated iron core-shell spindle array.
FIG. 6 shows the relative complex dielectric constants of the respective samples: (a) real part of the relative complex permittivity; (b) a relative complex permittivity imaginary part; (c) Real part of relative complex permeability and (d) imaginary part of relative complex permeability.
Fig. 7 is a graph of the samples of comparative example 1: (a) scanning electron micrographs; (b) reflection loss values at different thicknesses.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.
In the following examples, unless otherwise specified, the starting materials or the treatment techniques are all conventional and commercially available materials or conventional treatment techniques in the art.
Example 1:
referring to the flow shown in FIG. 1, micron tube Fe assembled by carbon-coated ferroferric oxide core-shell spindle array 3 O 4 Preparation of @ C-400:
firstly, 0.5793g ammonium molybdate tetrahydrate is weighed and dispersed in 30mL deionized water, then 2.5mL concentrated nitric acid solution (68% by mass) is added, stirred and transferred to a 50mL Teflon-lined reactor. And (3) placing the reaction kettle in an oven, keeping the reaction kettle at the temperature of 180 ℃ for 12 hours, cooling after the reaction is finished, separating, and drying to obtain the molybdenum trioxide micrometer rod.
Then, 30mg of molybdenum trioxide micrometer-rod powder was dispersed in 60mL of deionized water to obtain a white solution, 1.95g of ferric trichloride was added, ultrasonic stirring was performed, and the mixture was refluxed at 80 ℃ for 5 hours. And after the reaction is finished, centrifuging, separating and drying to obtain the product, namely the molybdenum trioxide core-shell micron rod coated with the iron oxyhydroxide array.
Then, 60mg of molybdenum trioxide core-shell micron rod powder coated with the iron oxyhydroxide array is weighed and dispersed in 100mL of deionized water to obtain a yellow solution, 120mg of tris (hydroxymethyl) aminomethane is added, and the solution A is obtained by ultrasonic stirring. And weighing 120mg of dopamine hydrochloride, adding the dopamine hydrochloride into the solution A, stirring and reacting for 2 hours, separating, cleaning and drying the obtained product to obtain the dopamine-coated iron oxyhydroxide array-assembled microtube.
Finally, weighing micrometer tube powder assembled by a polydopamine-coated iron oxyhydroxide array, calcining for 4 hours at 400 ℃ under the protection of hydrogen and argon gas, and heating at the rate of 2 ℃/min to obtain the target product of micrometer tube Fe assembled by a carbon-coated ferroferric oxide core-shell spindle array 3 O 4 The material @ C-400.
Example 2:
micron tube Fe-Fe assembled by carbon-coated iron-ferroferric oxide core-shell spindle array 3 O 4 @ C-500 preparation:
compared with example 1, the same is most true except that the calcination temperature is changed to 500 ℃.
Example 3:
preparing a micron tube Fe @ C-600 assembled by a carbon-coated iron core-shell spindle array:
compared with example 1, the same is mostly true except that the calcination temperature is changed to 600 ℃.
Comparative example 1:
compared with example 1, the same is most true except that the heat treatment temperature is changed to 700 ℃.
The microstructure of the microtubular material assembled by the core-shell spindle array in the above example was characterized by scanning electron microscopy (SEM, hitachi SEM S-4800), and the sample preparation method: and ultrasonically dispersing the powder sample in ethanol, and then dripping the powder sample on a conductive silicon wafer to be dried for testing. A series of composite material microstructures can be characterized by a transmission electron microscope (TEM, JEOL JEM-2100F), and a sample preparation method comprises the following steps: and ultrasonically dispersing the powder sample in ethanol, and then dripping the powder sample on a carbon-supported copper net for drying to test. X-ray diffraction spectra were measured on a bruker d8 Advance instrument. The complex relative permittivity and permeability in the range of 2.0-18.0GHz were tested using a vector network analyzer model N5230C.
FIG. 2 is a Scanning Electron Microscope (SEM) of a series of microtube materials assembled by core-shell spindle arrays synthesized by a regulation and control means, wherein a1-a2 in FIG. 2 are Fe products after calcination at 400 ℃ in hydrogen argon atmosphere in example 1 3 O 4 The microstructure of @ C-400, the surface of the outer shell is smooth, the whole body is in a spindle array assembly shape, and magnetic ferroferric oxide particles are arranged inside the outer shell; if the calcination temperature is raised to 500 ℃, the final product Fe-Fe 3 O 4 The external shell of @ C-500 is slightly rough, the internal components are obviously changed, and the inside is mainly magnetic iron and ferroferric oxide particles, such as b1-b2 in figure 2 (namely the product prepared in example 2); if the calcination temperature is raised to 600 ℃, the outer shell of the final product Fe @ C-600 is rough, and the internal components are significantly changed, and the interior is mainly magnetic iron particles, such as c1-c2 in FIG. 2 (i.e. the product obtained in example 3).
FIG. 3 shows a series of microtubes materials assembled by core-shell spindle arrays prepared in examples 1-3 aboveTransmission Electron Micrograph (TEM). As shown in FIG. 3a, fe 3 O 4 The outer carbon layer of the @ C-400 sample is integrally in a spindle array assembly shape, and meanwhile, ferroferric oxide particles are arranged inside the carbon layer and have more gaps; fe-Fe as shown in FIG. 3b 3 O 4 The @ C-500 sample outer carbon layer is integrally in a spindle array assembly shape, and meanwhile, iron-ferroferric oxide particles are arranged inside the sample outer carbon layer and have more gaps; as shown in FIG. 3c, the Fe @ C-600 outer carbon layer is irregular in shape, with iron particles inside and non-uniform in particle size. After three groups of samples are calcined, the carbon layer and the magnetic particles are still maintained at the temperature of 400 ℃ and 500 ℃, large particle metal is generated at the temperature of 600 ℃, and the spindle structure cannot be maintained.
Fig. 4 is an X-ray diffraction (XRD) analysis of the assembled microtubes of the core-shell spindle array with controllable magnetic components prepared in the above examples 1 to 3. In the figure, example 1 micron tube Fe assembled by carbon-coated ferroferric oxide core-shell spindle array 3 O 4 The diffraction peaks of the @ C-400 material at 2 θ =18.2 °, 30.1 °, 35.4 °, 37.1 °, 43.1 °, 53.4 °, 56.9 °, 62.5 °, 74.9 °, and 89.6 ° correspond to cubic Fe 3 O 4 The (111), (220), (311), (222), (400), (422), (511), (440), (622) and (731) crystal planes of (JCPDS Card No. 19-0629); while example 2 is Fe-Fe 3 O 4 The @ C-500 material and example 1 exhibited diffraction peaks at the same positions, corresponding to cubic Fe 3 O 4 (JCPDS Card No. 19-0629), while the diffraction peaks of example 2 at 2 θ =44.6 °, 65.0 ° and 82.3 ° correspond to the (110), (200) and (211) crystal planes of cubic Fe (JCPDS Card No. 06-0696); the diffraction peaks of example 3, fe @ C-600 at 2 θ =44.6 °, 65.0 ° and 82.3 ° correspond to the (110), (200) and (211) crystal planes of cubic Fe (JCPDS Card No. 06-0696). XRD pattern analysis proves the component information of the composite material, and the magnetic components of the spindle cores of examples 1, 2 and 3 are Fe in sequence 3 O 4 、Fe-Fe 3 O 4 And Fe.
FIG. 5 shows the values of the reflection loss at 2.0-18.0GHz frequency for microtube materials assembled with core-shell spindle arrays prepared in examples 1-3 above at 1.0-5.0mm thickness. As shown in FIG. 5aBy calcining at 400 ℃ in the presence of Fe 3 O 4 The sample @ C-400 reached a maximum reflection loss value of-18.1 dB at a thickness of 3.5 mm. Increasing the temperature, as shown in FIG. 5b, calcination at a temperature of 500 deg.C, fe-Fe 3 O 4 The sample of @ C-500 has a maximum reflection loss value of-46.1 dB at a thickness of 3.0 mm. However, continuing to increase the calcination temperature, calcination at 600 deg.C (as shown in FIG. 5 c), the maximum reflection loss for the Fe @ C-600 sample was only-16.4 dB at a thickness of 4.0 mm. In addition, by adjusting the thickness of a test sample, the effective response frequency bands of the three composite materials relate to C, X and a Ku waveband, which shows that the composite materials have controllable harmonic characteristics. The micron tube material assembled by the core-shell spindle body array simultaneously meets the practical application requirements of strong absorption, broadband response and low density, and is a potential high-performance wave-absorbing material.
FIG. 6 is a graph showing the real and imaginary parts of complex permittivity (ε ', ε ") and complex permeability (μ', μ") of microtube material assembled by core-shell spindle arrays prepared in examples 1-3 above, to reveal the mechanism of its excellent wave absorption properties. The wave absorbing performance of the composite material mainly derives from magnetic loss and polarization loss capability. With the rise of the calcining temperature, the spindle core components coated by the carbon layer are ferroferric oxide, iron-ferroferric oxide and iron in turn, the real part and the imaginary part of the magnetic conductivity are gradually increased, and the magnetic loss capacity of the composite material is improved due to the increase of the magnetic components. Meanwhile, with the increase of temperature, the carbon layer structure gradually collapses and is basically broken at 600 ℃, so that the complex dielectric constant is reduced, and the interface polarization loss is reduced. At 500 ℃, the carbon layer has a complete structure, the internal magnetic component is binary iron-ferroferric oxide, more interfaces exist, the interface polarization loss is enhanced, and the wave absorbing performance of the composite material is the best.
From a performance point of view, it is not the higher the temperature, the better the performance, i.e. the performance of Fe @ C-600 is not the best, while Fe-Fe 3 O 4 The properties of @ C-500 are best. This is because microwave absorption properties are related not only to dielectric loss and magnetic loss capabilities, but also to the structure of the material and to interfacial polarization capabilities. Example 1 namely Fe 3 O 4 The dielectric constant of @ C-400 is highest, corresponding toHas the largest dielectric loss capacity, but has a weak magnetic loss capacity, and thus has poor microwave absorption performance. And the product obtained by calcining the product of example 3, namely Fe @ C-600 at the temperature of 600 ℃ has the strongest magnetism and the best corresponding magnetic loss capability, but has low dielectric parameter, and simultaneously, the hollow spindle body array and the microtube structure are destroyed, the interface polarization is reduced, the dielectric loss and the polarization loss capability are reduced, so that the microwave absorption performance of Fe @ C-600 is not the best. Calcination at 500 ℃ only, example 2, fe-Fe 3 O 4 The @ C-500 performance is best, with maximum reflection loss values of-46.1 dB. Because of Fe-Fe 3 O 4 The core-shell core of the @ C-500 sample is magnetic metal iron and ferroferric oxide, has strong magnetic loss capacity, and meanwhile, the spindle array and the micron tube structure are still well maintained at 500 ℃, a large number of heterogeneous interfaces exist, a shell carbon layer is complete, and the sample has good dielectric loss and polarization loss capacity; fe-Fe 3 O 4 The @ C-500 material has stronger loss capacity and interface polarization as a whole, and shows stronger wave-absorbing performance. Therefore, the invention can be seen that a series of materials of carbon-coated magnetic components are prepared, and the materials have controllable dielectric loss and magnetic loss capacity, a heterogeneous interface and a hollow structure, so that the capacity of adjusting microwave absorption performance is realized.
FIG. 7 is a Scanning Electron Micrograph (SEM) of a comparative sample obtained in comparative example 1 above and a reflection loss value at a frequency of 2.0 to 18.0GHz at a thickness of 1.0 to 5.0 mm. As shown in fig. 7a, the spindle matrix structure of comparative example 1 was broken, the sample consisted of particles with non-uniform size, the spindle structure before calcination at the higher temperature of 700 ℃ was substantially maintained at the surface, and the internal magnetic particles diffused outward to form larger particles. As shown in fig. 7b, the sample of comparative example 1 has a poor wave-absorbing property, because the original core-shell carbon layer coated spindle array structure does not exist, the interface is greatly reduced, and the polarization loss capability is reduced, which results in the overall wave-absorbing property of the composite material being reduced. The calcination temperature is proved to be very important for the overall morphology regularity and the wave-absorbing performance of the carbon layer coated spindle body structure.
In general, the spindle array assembled microtube material of the present invention exhibits excellent electromagnetic wave loss capability in the 2.0-18.0GHz frequency range. According to the invention, molybdenum trioxide is used as a template, a hydroxyl ferric oxide array grows on the surface of the molybdenum trioxide, then polydopamine is coated on the surface of the molybdenum trioxide, and a micrometer tube material assembled by core-shell spindle body arrays with different magnetic particles can be prepared by changing the calcining temperature. The invention has simple synthesis process and excellent material performance, and has wide application prospect in the field of microwave absorption.
Comparative example 2:
most of them were the same as in example 2 except that the hydrogen argon atmosphere was changed to a pure argon atmosphere.
Treating under the protection of argon, and taking Fe as the internal component of the core-shell spindle body 3 O 4 Mainly, fe phase components are difficult to obtain, and the hydrogen and argon atmosphere plays an important role in controlling the internal magnetic components of the core-shell spindle.
Example 4:
compared to example 1, most of them are the same except that in this example: the addition ratio of ammonium molybdate tetrahydrate, concentrated nitric acid solution and deionized water is 0.4g:40mL of: 2mL, wherein the mass fraction of the concentrated nitric acid solution is 68%.
Example 5:
compared to example 1, most of them are the same except that in this example: the addition ratio of ammonium molybdate tetrahydrate, concentrated nitric acid solution and deionized water is 0.6g:20mL of: 3mL, wherein the mass fraction of the concentrated nitric acid solution is 65%.
Example 6:
compared to example 1, most of them are the same except that in this example: the oven was set at 160 ℃ and held for 14h.
Example 7:
compared to example 1, most of them are the same except that in this example: the temperature set in the oven was 200 ℃ and the holding time was 10h.
Example 8:
compared to example 1, most of them are the same except that in this example: the adding amount ratio of the molybdenum trioxide micron rods to the ferric trichloride is 25mg:1.5g.
Example 9:
compared to example 1, most of them are the same except that in this example: the adding amount ratio of the molybdenum trioxide micron rods to the ferric trichloride is 36mg:2.1g.
Example 10:
compared to example 1, most of them are the same except that in this example: the temperature of the heating reflux reaction is 60 ℃, and the time is 6h.
Example 11:
compared to example 1, most of them are the same except that in this example: the temperature of the heating reflux reaction is 100 ℃, and the time is 4h.
Example 12:
compared to example 1, most of them are the same except that in this example: the mass ratio of the molybdenum trioxide core-shell micron rods coated by the iron oxyhydroxide array, the tris (hydroxymethyl) aminomethane and the dopamine hydrochloride is 45:110:135.
example 13:
compared to example 1, most of them are the same except that in this example: the weight ratio of the molybdenum trioxide core-shell micron rods coated by the iron oxyhydroxide array, the tris (hydroxymethyl) aminomethane and the dopamine hydrochloride is 76:135:110.
the embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.

Claims (6)

1. A preparation method of a microwave absorbing material of a micron tube assembled by a core-shell spindle array is characterized by comprising the following steps:
(1) Weighing ammonium molybdate tetrahydrate, dispersing the ammonium molybdate tetrahydrate in deionized water, adding a concentrated nitric acid solution, stirring, reacting, separating and drying to obtain molybdenum trioxide micrometer rods;
(2) Dispersing the molybdenum trioxide micrometer rod in deionized water, adding ferric trichloride, performing ultrasonic treatment, performing heating reflux reaction, separating and drying the obtained reaction product to obtain a molybdenum trioxide micrometer rod coated with a hydroxyl ferric oxide array;
(3) Weighing molybdenum trioxide nanorods coated by a ferric hydroxide array, dispersing the molybdenum trioxide nanorods into deionized water, adding tris (hydroxymethyl) aminomethane, performing ultrasonic stirring to obtain a solution A, continuously adding dopamine hydrochloride, performing stirring reaction, separating, cleaning and drying the obtained product to obtain a polydopamine-coated ferric hydroxide array-assembled microtube;
(4) Placing a microtube assembled by a polydopamine-coated iron oxyhydroxide array under the protection of hydrogen and argon gas, and calcining to obtain a target product;
in the step (1), the adding amount ratio of ammonium molybdate tetrahydrate, concentrated nitric acid solution and deionized water is 0.5793g:2.5mL:30mL, wherein the mass fraction of the concentrated nitric acid solution is 65-68%;
in the step (2), the adding amount ratio of the molybdenum trioxide micrometer rod to ferric trichloride is (25 to 36) mg: (1.5 to 2.1) g;
in the step (3), the molybdenum trioxide core-shell micron rods are coated by the iron oxyhydroxide array, and the mass ratio of the tris (hydroxymethyl) aminomethane to the dopamine hydrochloride is (45-76): (110 to 135): (110 to 135);
in the step (4), the calcining temperature is 400-600 ℃, and the calcining time is 3-5h.
2. The preparation method of the microwave absorbing material with the micron tubes assembled by the core-shell spindle arrays according to claim 1, wherein in the step (1), the reaction temperature is 160 to 200 ℃ and the reaction time is 10 to 14h.
3. The preparation method of the microwave absorbing material of the micron tube assembled by the core-shell spindle array according to claim 1, wherein in the step (2), the temperature of the heating reflux reaction is 60 to 100 ℃, and the time is 4 to 6 hours.
4. The preparation method of the microwave absorbing material with the micron tubes assembled by the core-shell spindle arrays is characterized in that in the step (3), the stirring reaction time is 1 to 3 hours.
5. The microwave absorbing material is characterized by having a micron tube structure assembled by the core-shell spindle array, wherein the inner core layer of the core-shell spindle is magnetic metallic iron and/or ferroferric oxide particles, and the outer shell layer is a carbon layer.
6. The use of the core-shell spindle array assembled microtube microwave absorbing material of claim 5 in the field of microwave absorption.
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