CN114276781B - MO@NC core-shell structure type nano wave-absorbing material and preparation method thereof - Google Patents
MO@NC core-shell structure type nano wave-absorbing material and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a preparation method of an MO@NC core-shell nano wave-absorbing material, which comprises the following steps: adding the MO@C core-shell structural material into acid liquor, heating and stirring for 1-5h, and drying to obtain an etched MO@C core-shell structural material; and heating the etched MO@C core-shell structural material to 500-900 ℃ in a nitrogen source atmosphere, and preserving heat for 2-6h to obtain the MO@NC core-shell nano wave-absorbing material. Wherein M is Fe, co or Ni. The invention also discloses the MO@NC core-shell nano wave-absorbing material prepared by the preparation method of the MO@NC core-shell nano wave-absorbing material. The MO@NC core-shell nano wave-absorbing material prepared by the method has lower maximum reflection loss, wider effective bandwidth and stronger wave-absorbing capacity.
Description
Technical Field
The invention belongs to the field of high-frequency GHz electromagnetic wave interference resistance, and particularly relates to an MO@NC core-shell structure type nano wave-absorbing material and a preparation method thereof.
Background
Stealth technology is a technology that makes it difficult to detect, identify, track, and attack by controlling and reducing the signature of a weapon system. In modern and future wars, radar is the most reliable means of detecting targets, and research on stealth technology focuses on radar stealth.
In recent years, research and development of a light, broadband, strong-absorption and high-stability high-efficiency wave-absorbing material is a research hot spot. In general, excellent impedance matching characteristics can achieve as much of the incident electromagnetic wave as possible into the interior of the wave-absorbing material. Based on this, in order to ensure that the target material has good microwave attenuation characteristics, it is important to ensure that the wave-absorbing material has excellent impedance matching characteristics in a wide frequency range.
Currently, in two application fields of civil and military, research on how to absorb electromagnetic waves or convert electromagnetic waves into heat energy is a key to obtain efficient wave absorbing materials. Among various wave-absorbing materials, fe 3 O 4 Has the remarkable advantages of low preparation cost, easy preparation, strong low-frequency absorption and the like, and is the wave-absorbing material most widely applied in ferrite. However, conventional Fe 3 O 4 The wave-absorbing material has dielectric lossThe disadvantages of weak energy consumption, snoek limit, narrow absorption band, etc., limit further practical application.
By the researchers, fe 3 O 4 Is compounded with dielectric loss material to enhance dielectric loss capability and improve impedance matching characteristics. For example, chinese patent publication No. CN112839500a discloses a yolk shell hollow ferroferric oxide @ air @ carbon nanocomposite wave-absorbing material and a method for preparing the same, comprising: the method comprises the following steps: (1) Coating SiO on the surface of hollow ferroferric oxide nano particles 2 The method comprises the steps of carrying out a first treatment on the surface of the (2) carboxylation modification is carried out on the surface; (3) growing MIL-100 (Fe) on the surface in situ; (4) calcining at high temperature under nitrogen atmosphere; (5) Heating and stirring in alkali liquor to remove SiO 2 And (3) washing and drying the layers to obtain the hollow ferroferric oxide air carbon nano composite wave-absorbing material with the yolk shell. The maximum absorption strength of the yolk shell hollow ferroferric oxide@air@carbon nano composite wave absorbing material obtained by the method can reach-20.8 dB.
It should be noted, however, that the above-mentioned patent is not concerned with the separate regulation of the magnetic and electric components of the material produced, and therefore the regulation effect on the impedance matching thereof is limited. At present, how to optimize the attenuation characteristics of high-frequency electromagnetic waves for the magnetic/electric composite wave absorbing material is a research hot spot and a difficult point in the field.
In conclusion, the fine microstructure/component regulation and control are respectively carried out on the magnetic and electric components of the composite nano material, and the composite nano material has wide practical application prospect in the military and civil fields.
Disclosure of Invention
The invention provides a preparation method of an MO@NC core-shell structured nano wave-absorbing material, which has the advantages of lower maximum reflection loss, wider effective bandwidth and stronger wave-absorbing capacity.
A preparation method of MO@NC core-shell structured nano wave-absorbing material comprises the following steps:
and adding the MO@C core-shell structural material into acid liquor, heating and stirring for 1-5h, drying to obtain an etched MO@C core-shell structural material, and heating the etched MO@C core-shell structural material to 500-900 ℃ under a nitrogen source atmosphere for 2-6h to obtain the MO@NC core-shell nano wave-absorbing material, wherein M is Fe, co or Ni.
According to the invention, MO is a magnetic material, and the magnetic performance is regulated and controlled by utilizing acid liquor to controllably etch the magnetic material; and (3) carrying out selective nitrogen doping (namely NC) on the C core-shell structural material through a heat treatment process under a nitrogen atmosphere so as to realize linear regulation and control of conductivity characteristics in an NC layer and realize dielectric regulation and control on the NC material. In summary, through the respective regulation and control of the magnetic and electric components in the MO@C material, the optimization of the impedance matching characteristics of the MO@NC core-shell structure type nano wave-absorbing material is finally achieved, and a foundation is laid for obtaining the high-performance wave-absorbing characteristics.
The content of N in the MO@NC is 0.5-5wt%, the content of C is 5-39.5wt%, and the content of M is 50-90wt%.
The acid liquor is one of hydrochloric acid, sulfuric acid, nitric acid, citric acid, oxalic acid or acetic acid.
The concentration of the acid liquor is 1-10mol/L. And selectively etching the MO material in the MO@NC through acid liquor concentration control to obtain proper MO magnetic component content, thereby obtaining better magnetic characteristics. Too high an acid solution concentration can cause too high etching speed of the MO material, and linear regulation and control of the magnetic components are difficult to realize.
The heating temperature of the heating and stirring is 30-80 ℃. Excessive temperature can cause excessive etching speed of MO material, and linear regulation of magnetic components is difficult to realize.
The nitrogen source is one of melamine, mono-cyanamide or dicyandiamide.
The invention also provides the MO@NC core-shell structure type nano wave-absorbing material prepared by the preparation method of the MO@NC core-shell structure type nano wave-absorbing material.
The MO@NC core-shell structure type nano wave-absorbing material is characterized in that the surfaces of MO particles are completely or partially wrapped by a carbon layer to form an MO@C core-shell structure type nano material, the surfaces of C shell layers in the MO@C core-shell structure are completely or partially penetrated by nitrogen to form a nitrogen doped carbon layer (namely NC), and finally the MO@NC core-shell structure type nano wave-absorbing material with broadband and strong absorption characteristics is formed. Wherein M is Fe, co or Ni.
The MO@NC core-shell nano wave-absorbing material has the maximum reflection loss (RL max ) The effective bandwidth (EAB) is 0.5-3.6GHz at-12-35 dB.
Compared with the prior art, the invention has the beneficial effects that:
according to the invention, the carbon coated on the surface of the magnetic material is selectively etched, nitrogen is doped in the carbon through a heat treatment process to accurately control the electric components, the magnetic components are accurately regulated and controlled through adding the magnetic material, and the magnetic performance of the material is not influenced by the steps of the method for accurately controlling the electric components, so that the impedance matching characteristic of the material is comprehensively optimized, and a matching foundation is laid for obtaining broadband and strong-absorption microwave attenuation characteristics.
Drawings
FIG. 1 shows Fe prepared in example 1 3 O 4 TEM image of NC core-shell nano wave-absorbing material;
FIG. 2 is Co prepared in example 2 3 O 4 TEM image of NC core-shell nanoscopic material.
Detailed Description
The invention is further described below in connection with specific examples, which are not intended to limit the scope of the invention. The materials and instruments used in the examples below are all commercially available.
Example 1
Fe realized through magnetoelectric cooperative regulation and control 3 O 4 The method for efficiently attenuating microwaves of the @ NC core-shell nanostructure comprises the following steps:
(1) According to Fe (OH) 3 Respectively weighing corresponding amounts of ferric chloride and sodium hydroxide, fully stirring, and preserving the temperature at 80 ℃ for 48 hours. After the reaction is finished, respectively washing with deionized water and ethanol for 3 times to obtain Fe 2 O 3 The powder samples were dried in a vacuum oven at 80℃for 5 hours.
(2) Taking 0.5g Fe in (1) 2 O 3 Sample, fe is obtained by adopting a polydopamine coating mode 2 O 3 A core-shell structured material of Polydopamine (PDA).
(3) Taking 0.5g Fe in (2) 2 O 3 Placing the material of the core-shell structure of the @ polydopamine into 5mol/L hydrochloric acid solution, uniformly stirring for 0, 3 and 5 hours at 50 ℃, and respectively cleaning with deionized water and ethanol for 3 times to obtain Fe 2 O 3 -0@PDA、Fe 2 O 3 -3@PDA and Fe 2 O 3 -5@pda powder samples and dried in a vacuum oven at 80 ℃ for 5 hours.
(4) Taking 0.5g Fe in (3) respectively 2 O 3 -3@PDA with Fe 2 O 3 Placing a 5@PDA powder sample in a vacuum furnace, placing melamine (nitrogen source) in a mass ratio of 1:1 at the front section of the sample, and respectively treating at 700 ℃ for 3 hours and 5 hours to obtain Fe 3 O 4 -3@NC-3、Fe 3 O 4 -3@NC-5、Fe 3 O 4 -5@NC-3 and Fe 3 O 4 -5@NC-5 core-shell wave absorbing material. In addition, 0.5g of Fe in (3) was taken 2 O 3 -0@PDA sample is treated for 3 hours and 5 hours at 700 ℃ in a vacuum furnace under the condition of no nitrogen source to obtain Fe 3 O 4 -0@NC-0-3 and Fe 3 O 4 -0@NC-0-5 core-shell wave absorbing material. As shown in FIG. 1, fe was prepared 3 O 4 the-3@NC-5 material has a remarkable core-shell nano structure. Specifically, the shell C layer contains Fe 3 O 4 The core material is uniformly coated therein. Furthermore, as can be seen from TEM image, fe 3 O 4 Under the etching of acid liquor, the volume of the material is obviously reduced compared with that of the material before etching, and thus, an adjusting space is provided for adjusting and controlling the magnetic components of the material.
(5) The six samples in (4) were mixed with paraffin wax (40% by mass ratio: 60%) and pressed into a ring-shaped sample (thickness: 2.00 mm) having an outer diameter of 7.00mm and an inner diameter of 3.04mm, and their complex permittivity and complex permeability (. Epsilon.,. Mu.') in the 2-18GHz band were measured by a Vector Network Analyzer (VNA). And calculating the maximum Reflection Loss (RL) of the material by a classical transmission line theoretical calculation formula max ) And corresponding effective bandwidth (RL<-10db, eab) value. The corresponding numerical pairs are shown in Table 1:
table 1 shows the Fe prepared in example 1 3 O 4 Nano @ NC core-shellElectromagnetic parameters and effective bandwidth
Example 2
Co is realized through magnetoelectric cooperative regulation and control 3 O 4 The method for efficiently attenuating microwaves of the @ NC core-shell nanostructure comprises the following steps:
(1) The preparation method comprises the following steps: according to Co (OH) 2 Respectively weighing cobalt acetate and ammonia water solution with corresponding amounts, fully stirring, and carrying out hydrothermal reaction for 24 hours at 180 ℃. After the reaction is finished, respectively washing the mixture with deionized water and ethanol for 3 times to obtain Co 3 O 4 The powder samples were dried in a vacuum oven at 80℃for 5 hours.
(2) Taking 0.5g Co of (1) 3 O 4 Sample, co is obtained by adopting a polydopamine coating mode 3 O 4 A core-shell structured material of Polydopamine (PDA).
(3) Taking 0.5g Co of (2) 3 O 4 Placing the material of the core-shell structure of the @ polydopamine into 5mol/L hydrochloric acid solution, uniformly stirring for 0, 3 and 5 hours at 50 ℃, and respectively cleaning with deionized water and ethanol for 3 times to obtain Co 3 O 4 -0@PDA、Co 3 O 4 -3@PDA and Co 3 O 4 -5@pda powder samples and dried in a vacuum oven at 80 ℃ for 5 hours.
(4) Taking 0.5g Co in (3) 3 O 4 -3@PDA with Co 3 O 4 Placing a 5@PDA powder sample in a vacuum furnace, placing melamine (nitrogen source) in a mass ratio of 1:1 at the front section of the sample, and respectively treating at 700 ℃ for 3 hours and 5 hours to obtain Co 3 O 4 -3@NC-3、Co 3 O 4 -3@NC-5、Co 3 O 4 -5@NC-3 and Co 3 O 4 -5@NC-5 core-shell wave absorbing material. In addition, 0.5g Co in (3) was taken 3 O 4 -0@PDA sample is treated for 3 hours and 5 hours at 700 ℃ in a vacuum furnace under the condition of no nitrogen source to obtain Co 3 O 4 -0@NC-0-3 and Co 3 O 4 -0@NC-0-5 core-shell wave absorbing material. As shown in FIG. 2, co was produced 3 O 4 the-3@NC-5 material has a remarkable core-shell nano structure. Specifically, shell C layer. Co is to be 3 O 4 The core material is uniformly coated therein. Furthermore, as can be seen from TEM images, co 3 O 4 Under the etching of acid liquor, the volume of the material is obviously reduced compared with that of the material before etching, and thus, an adjusting space is provided for adjusting and controlling the magnetic components of the material.
(5) The six samples of (4) were mixed with paraffin wax (50% by mass ratio: 50%) and pressed into annular samples (thickness: 2.00 mm) having an outer diameter of 7.00mm and an inner diameter of 3.04mm, and their complex dielectric constants and complex permeability (. Epsilon.,. Mu.') in the 2-18GHz band were measured by a Vector Network Analyzer (VNA). And calculating the maximum Reflection Loss (RL) of the material by a classical transmission line theoretical calculation formula max ) And corresponding effective bandwidth (RL<-10db, eab) value. The corresponding numerical pairs are shown in Table 2:
table 2 shows the Co produced in example 2 3 O 4 Electromagnetic parameters and effective bandwidth of @ NC core-shell nano
The above description is only exemplary embodiments of the invention and is not intended to limit the invention in any way. Any person skilled in the art will readily appreciate that many variations and modifications are possible in the arrangements of the present invention using the methods and techniques disclosed above without departing from the spirit and scope of the invention. Therefore, any simple modification, equivalent substitution, equivalent variation and other technical means of the above embodiments according to the technical substance of the present invention fall within the scope of the technical solution of the present invention.
Claims (8)
1. The preparation method of the MO@NC core-shell structured nano wave-absorbing material is characterized by comprising the following steps of:
adding the MO@C core-shell structural material into acid liquor, heating and stirring for 1-5h, drying to obtain an etched MO@C core-shell structural material, and heating the etched MO@C core-shell structural material to 500-900 ℃ under a nitrogen source atmosphere for 2-6h to obtain an MO@NC core-shell structural nano wave-absorbing material, wherein M is Fe or Co;
the MO@C core-shell structure type material is Fe 2 O 3 Material of the @ polydopamine core-shell structure type or Co 3 O 4 A polydopamine core-shell structure type material;
MO in the MO@NC core-shell structured nano wave-absorbing material is Fe 3 O 4 Or Co 3 O 4 ；
The nitrogen source is one or more of melamine, mono-cyanamide or dicyandiamide.
2. The method for preparing the MO@NC core-shell structured nano wave-absorbing material according to claim 1, wherein the content of N in the MO@NC core-shell structured nano wave-absorbing material is 0.5-5wt%, the content of C is 5-39.5wt%, and the content of M is 50-90wt%.
3. The method for preparing the mo@nc core-shell structured nano wave absorbing material according to claim 1, wherein the acid liquid is one of hydrochloric acid, sulfuric acid, nitric acid, citric acid, oxalic acid and acetic acid.
4. The method for preparing the MO@NC core-shell structured nano wave-absorbing material according to claim 1, wherein the acid solution concentration is 1-10mol/L.
5. The method for preparing the MO@NC core-shell structured nano wave-absorbing material according to claim 1, wherein the heating temperature of heating and stirring is 30-80 ℃.
6. The mo@nc core-shell structured nano wave-absorbing material prepared by the preparation method of the mo@nc core-shell structured nano wave-absorbing material according to any one of claims 1 to 5.
7. The MO@NC core-shell structured nano wave-absorbing material prepared by the preparation method of the MO@NC core-shell structured nano wave-absorbing material according to claim 6, wherein the surfaces of MO particles in the MO@NC core-shell structured nano wave-absorbing material are completely or partially wrapped by a carbon layer, and the carbon shell layer is partially or completely permeated by nitrogen.
8. The MO@NC core-shell structured nano wave-absorbing material prepared by the preparation method of the MO@NC core-shell structured nano wave-absorbing material is characterized in that the maximum reflection loss of the MO@NC core-shell structured nano wave-absorbing material is-12 to-35 dB, and the effective bandwidth is 0.5-3.6GHz.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109275329A (en) * | 2018-09-18 | 2019-01-25 | 北京科技大学 | A kind of preparation method of nano core-shell absorbing material |
| CN109437156A (en) * | 2018-11-13 | 2019-03-08 | 上海师范大学 | A kind of preparation method of nitrogen-doped carbon nanometer pipe |
| CN109755442A (en) * | 2019-02-28 | 2019-05-14 | 大连理工大学 | A kind of preparation method of network-like carbon load iron base compound material and its application on lithium-sulfur cell |
| CN111710991A (en) * | 2020-06-24 | 2020-09-25 | 大连理工大学 | Spiral carbon nano coil/core-shell structure magnetic nano particle composite material, preparation method and application thereof in electromagnetic wave field |
| CN112210345A (en) * | 2020-09-23 | 2021-01-12 | 南昌航空大学 | Method for improving performance of wave-absorbing material with spherical composite core-shell structure |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109275329A (en) * | 2018-09-18 | 2019-01-25 | 北京科技大学 | A kind of preparation method of nano core-shell absorbing material |
| CN109437156A (en) * | 2018-11-13 | 2019-03-08 | 上海师范大学 | A kind of preparation method of nitrogen-doped carbon nanometer pipe |
| CN109755442A (en) * | 2019-02-28 | 2019-05-14 | 大连理工大学 | A kind of preparation method of network-like carbon load iron base compound material and its application on lithium-sulfur cell |
| CN111710991A (en) * | 2020-06-24 | 2020-09-25 | 大连理工大学 | Spiral carbon nano coil/core-shell structure magnetic nano particle composite material, preparation method and application thereof in electromagnetic wave field |
| CN112210345A (en) * | 2020-09-23 | 2021-01-12 | 南昌航空大学 | Method for improving performance of wave-absorbing material with spherical composite core-shell structure |
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