CN116377618A - Fe-Co alloy/C composite nanofiber and preparation method and application thereof - Google Patents
Fe-Co alloy/C composite nanofiber and preparation method and application thereof Download PDFInfo
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- 229910017061 Fe Co Inorganic materials 0.000 title claims abstract description 74
- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 74
- 239000000956 alloy Substances 0.000 title claims abstract description 74
- 239000002121 nanofiber Substances 0.000 title claims abstract description 68
- 239000002131 composite material Substances 0.000 title claims abstract description 59
- 238000002360 preparation method Methods 0.000 title abstract description 7
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical class C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims abstract description 17
- 239000002134 carbon nanofiber Substances 0.000 claims abstract description 13
- 239000002105 nanoparticle Substances 0.000 claims abstract description 13
- 238000000034 method Methods 0.000 claims abstract description 12
- 238000010041 electrostatic spinning Methods 0.000 claims abstract description 11
- 239000011358 absorbing material Substances 0.000 claims abstract description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 6
- 239000010439 graphite Substances 0.000 claims abstract description 6
- 238000010438 heat treatment Methods 0.000 claims abstract description 5
- 239000006096 absorbing agent Substances 0.000 claims description 23
- 239000012188 paraffin wax Substances 0.000 claims description 22
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 20
- 238000011049 filling Methods 0.000 claims description 18
- 238000001035 drying Methods 0.000 claims description 14
- 229920002239 polyacrylonitrile Polymers 0.000 claims description 12
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 10
- 239000002243 precursor Substances 0.000 claims description 10
- 238000003763 carbonization Methods 0.000 claims description 9
- FJDJVBXSSLDNJB-LNTINUHCSA-N cobalt;(z)-4-hydroxypent-3-en-2-one Chemical compound [Co].C\C(O)=C\C(C)=O.C\C(O)=C\C(C)=O.C\C(O)=C\C(C)=O FJDJVBXSSLDNJB-LNTINUHCSA-N 0.000 claims description 7
- 230000001590 oxidative effect Effects 0.000 claims description 6
- 238000010000 carbonizing Methods 0.000 claims description 5
- LZKLAOYSENRNKR-LNTINUHCSA-N iron;(z)-4-oxoniumylidenepent-2-en-2-olate Chemical compound [Fe].C\C(O)=C\C(C)=O.C\C(O)=C\C(C)=O.C\C(O)=C\C(C)=O LZKLAOYSENRNKR-LNTINUHCSA-N 0.000 claims description 5
- 239000007788 liquid Substances 0.000 claims description 5
- 239000012299 nitrogen atmosphere Substances 0.000 claims description 5
- 238000003756 stirring Methods 0.000 claims description 4
- 238000009826 distribution Methods 0.000 claims description 3
- CDVAIHNNWWJFJW-UHFFFAOYSA-N 3,5-diethoxycarbonyl-1,4-dihydrocollidine Chemical compound CCOC(=O)C1=C(C)NC(C)=C(C(=O)OCC)C1C CDVAIHNNWWJFJW-UHFFFAOYSA-N 0.000 claims description 2
- 238000001523 electrospinning Methods 0.000 claims description 2
- 239000011159 matrix material Substances 0.000 claims description 2
- 238000004132 cross linking Methods 0.000 abstract description 3
- 230000008859 change Effects 0.000 abstract description 2
- 230000001105 regulatory effect Effects 0.000 abstract 1
- 238000010521 absorption reaction Methods 0.000 description 12
- 238000012360 testing method Methods 0.000 description 8
- 230000035699 permeability Effects 0.000 description 7
- 230000010287 polarization Effects 0.000 description 7
- 229920000049 Carbon (fiber) Polymers 0.000 description 5
- 239000004917 carbon fiber Substances 0.000 description 5
- 229910052742 iron Inorganic materials 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 230000007246 mechanism Effects 0.000 description 5
- 229910000531 Co alloy Inorganic materials 0.000 description 4
- 238000012512 characterization method Methods 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 239000002122 magnetic nanoparticle Substances 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 238000001000 micrograph Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 239000000835 fiber Substances 0.000 description 3
- 230000001788 irregular Effects 0.000 description 3
- 238000003760 magnetic stirring Methods 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
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- 239000002245 particle Substances 0.000 description 3
- 229910003481 amorphous carbon Inorganic materials 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 239000011258 core-shell material Substances 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
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- 238000004220 aggregation Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003610 charcoal Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000013016 damping Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
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- 230000002500 effect on skin Effects 0.000 description 1
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
- D01F9/08—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
- D01F9/12—Carbon filaments; Apparatus specially adapted for the manufacture thereof
- D01F9/14—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments
- D01F9/20—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products
- D01F9/21—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D01F9/22—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyacrylonitriles
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K3/00—Materials not provided for elsewhere
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F1/00—General methods for the manufacture of artificial filaments or the like
- D01F1/02—Addition of substances to the spinning solution or to the melt
- D01F1/10—Other agents for modifying properties
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K9/00—Screening of apparatus or components against electric or magnetic fields
- H05K9/0073—Shielding materials
- H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K9/00—Screening of apparatus or components against electric or magnetic fields
- H05K9/0073—Shielding materials
- H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
- H05K9/009—Electromagnetic shielding materials, e.g. EMI, RFI shielding comprising electro-conductive fibres, e.g. metal fibres, carbon fibres, metallised textile fibres, electro-conductive mesh, woven, non-woven mat, fleece, cross-linked
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- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electromagnetism (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Manufacturing & Machinery (AREA)
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- Organic Chemistry (AREA)
- Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
- Chemical Or Physical Treatment Of Fibers (AREA)
- Carbon And Carbon Compounds (AREA)
Abstract
The invention discloses Fe-Co alloy/C composite nanofiber as well as a preparation method and application thereof, and belongs to the technical field of wave-absorbing materials. The method is characterized in that the method adopts an electrostatic spinning combined with a later heat treatment one-step method, is in a three-dimensional cross-linking morphology, and consists of Fe-Co alloy nano particles and carbon nano fibers, wherein the Fe-Co alloy nano particles are uniformly distributed on the surfaces of the carbon nano fibers, and the outer sides of the Fe-Co alloy nano particles are coated with a layer of graphite; in the Fe-Co alloy nano particles, the molar ratio of Fe to Co is 1-3: 1 to 3. According to the Fe-Co alloy/C composite nanofiber, the electromagnetic parameters are effectively regulated and controlled by the change of the mole ratio of the doped Fe to Co, and when the mole ratio of the doped Fe to Co is 1:1, the obtained Fe-Co alloy/C composite nanofiber has better impedance matching and electromagnetic wave attenuation capability and the best wave absorbing performance.
Description
Technical Field
The invention belongs to the technical field of wave-absorbing materials, and particularly relates to Fe-Co alloy/C composite nanofiber, and a preparation method and application thereof.
Background
The disclosure of this background section is only intended to increase the understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art already known to those of ordinary skill in the art.
With the rapid development of modern technology, wireless communication and radar technology bring great convenience to human society, but simultaneously, a great deal of problems of electromagnetic interference, electromagnetic pollution and the like are also generated, so that the problems of electromagnetic interference overcoming, electromagnetic hazard prevention and novel and efficient electromagnetic wave absorption material research have become a great conception in the field of current material science.
With the intensive research of novel and efficient wave absorbing materials, in recent years, there has been a great demand for "wide, strong, light, thin" electromagnetic wave absorbers. Accordingly, carbon fiber materials having advantages of large surface area, low density, stable physicochemical properties, low cost, and the like are widely used in electromagnetic wave absorbers. However, carbon fiber materials also suffer from certain drawbacks, such as: the loss mechanism is single, and the multi-band absorption performance is poor; the conductivity is high, so that the skin effect is serious and the impedance matching is unbalanced; narrower absorption bands, etc. Therefore, many techniques introduce magnetic metals (such as Fe, co, etc.) by coating the surface with the magnetic metals and their oxides, thereby improving the electromagnetic wave attenuation capability of the material. However, the magnetic metal and the oxide coating thereof introduced by the technology are positioned on the surface of the carbon fiber, so that the magnetic metal and the oxide coating are easy to oxidize and corrode, have poor stability, and have thicker most of the coating, so that the application of the carbon fiber composite material in many scenes is limited.
Disclosure of Invention
In order to solve the defects in the prior art, the invention aims to provide the Fe-Co alloy/C composite nanofiber as well as the preparation method and the application thereof.
In order to achieve the above purpose, the technical scheme of the invention is as follows:
according to the first aspect of the invention, a Fe-Co alloy/C composite nanofiber is provided, the Fe-Co alloy/C composite nanofiber is in a three-dimensional cross-linked morphology, and consists of Fe-Co alloy nanoparticles and carbon nanofibers, wherein the Fe-Co alloy nanoparticles are uniformly distributed on the surfaces of the carbon nanofibers, and the outer sides of the Fe-Co alloy nanoparticles are wrapped with a layer of graphite;
in the Fe-Co alloy nano particles, the molar ratio of Fe to Co is 1-3: 1 to 3.
The Fe-Co alloy/C composite nanofiber synthesized by the method has a three-dimensional network structure, fe-Co alloy nano particles are uniformly distributed on the surface of the three-dimensional network and are wrapped by a graphite layer, and the Fe-Co alloy/C composite nanofiber has strong oxidation resistance and corrosion resistance and strong stability, and is a light-weight, broadband and strong-absorption wave-absorbing material.
In some embodiments of the invention, the Fe-Co alloy/C composite nanofiber has a diameter distribution of 100nm to 300nm.
In some embodiments of the invention, the molar ratio of Fe to Co is 1:1.
in a second aspect of the present invention, a method for preparing the Fe-Co alloy/C composite nanofiber described above is provided, comprising the steps of:
step 1: dissolving polyacrylonitrile in N, N-dimethylformamide, and heating and stirring to fully dissolve the polyacrylonitrile; then adding ferric acetylacetonate and cobalt acetylacetonate, and continuing heating and stirring to obtain a uniform precursor solution;
step 2: and (3) carrying out electrostatic spinning by using the precursor solution in the step (1), drying and pre-oxidizing the spun nanofiber after the electrostatic spinning is finished, and then carbonizing the pre-oxidized sample in a nitrogen atmosphere to obtain the Fe-Co alloy/C composite nanofiber.
In some embodiments of the invention, the ratio of polyacrylonitrile, N-dimethylformamide, iron acetylacetonate and cobalt acetylacetonate is 1g:9g:0.003mol.
In some embodiments of the invention, the parameters of the electrospinning are: the voltage is +13kV/-3kV, the liquid pushing speed is 0.04mm/min, and the receiving distance is 15cm.
In some embodiments of the invention, the drying conditions of the drying are: drying at 50-100 deg.c for 12-36 hr, preferably at 60 deg.c for 24 hr.
In some embodiments of the invention, the pre-oxidation is performed at 200-250 ℃ for 1-3 hours.
In some embodiments of the invention, the carbonization conditions are maintained at 500-1000 ℃ for 1-3 hours, preferably at 800 ℃ for 2 hours.
The Fe-Co alloy/C composite nanofiber prepared by the invention has stronger dielectric loss, stronger electromagnetic wave attenuation capability and better wave absorbing performance, so the third aspect of the invention provides the application of the Fe-Co alloy/C composite nanofiber in wave absorbing materials.
In a fourth aspect of the present invention, there is provided a wave absorber, comprising a paraffin as a matrix, wherein the Fe-Co alloy/C composite nanofiber is filled in the paraffin with a filling rate of 15%, and the thickness of the wave absorber is 1 to 5mm. It is found that when the ratio of the amount of the added iron and cobalt is 1:1, the dielectric loss is strongest, so that the electromagnetic wave attenuation capability is stronger, and the wave absorption performance is best. The maximum reflection loss is-18.66 GHz when the thickness of the wave absorber is 1.08mm, and the maximum effective absorption bandwidth is 4.2GHz (13.9-18 GHz) when the thickness is 1.22 mm.
In a fifth aspect of the invention, there is provided the use of an Fe-Co alloy for increasing the dielectric loss of a carbon nanofiber wave absorbing material.
The beneficial effects of the invention are as follows:
in the Fe-Co alloy/C composite nanofiber prepared by the invention, the Fe-Co alloy particles effectively improve the impedance matching characteristic and the electromagnetic wave attenuation capability of the carbon nanofiber. The change of the mole ratio of the doped Fe and Co effectively regulates and controls electromagnetic parameters, and when the mole ratio of the doped Fe and Co is 1:1, the obtained Fe-Co alloy/C composite nanofiber has better impedance matching and electromagnetic wave attenuation capability and the best wave absorbing performance.
In the Fe-Co alloy/C composite nanofiber prepared by the invention, the core-shell structure of the Fe-Co alloy/C can improve the oxidation resistance and corrosion resistance of the wrapped magnetic nanoparticle, so that the Fe-Co alloy/C composite nanofiber has good wave absorption stability.
The Fe-Co alloy/C composite nanofiber prepared by the invention is used as a wave absorber, and has the advantages of light weight, thin thickness, wide frequency band and strong absorption capacity; the preparation process is simple and safe, convenient to operate, short in preparation period and easy to industrialize.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention.
FIG. 1 is a scanning electron microscope image of the Fe-Co alloy/C composite nanofiber obtained after carbonization in example 1;
FIG. 2 is a scanning electron microscope image of the Fe-Co alloy/C composite nanofiber obtained after carbonization in example 2;
FIG. 3 is a scanning electron microscope image of the Fe-Co alloy/C composite nanofiber obtained after carbonization in example 3;
FIG. 4 is a transmission electron microscope image of the Fe-Co alloy/C composite nanofiber obtained after carbonization of example 1;
FIG. 5 is a graph of reflection loss of the Fe-Co alloy/C composite nanofiber prepared in example 1 after being mixed with paraffin wax according to a filling rate of 15%, wherein a is a three-dimensional reflection loss graph, and b is a two-dimensional reflection curve with different thicknesses;
FIG. 6 is a graph of reflection loss of the Fe-Co alloy/C composite nanofiber prepared in example 2 after being mixed with paraffin wax according to a filling rate of 15%, wherein a is a three-dimensional reflection loss graph, and b is a two-dimensional reflection curve with different thicknesses;
FIG. 7 is a graph showing the reflection loss of the Fe-Co alloy/C composite nanofiber prepared in example 3 after being mixed with paraffin wax according to a filling rate of 15%, wherein a is a three-dimensional reflection loss graph, and b is a two-dimensional reflection curve with different thicknesses;
FIG. 8 is a graph showing the damping constants of the Fe-Co alloy/C composite nanofibers obtained in example 1, example 2, and example 3 after being mixed with paraffin wax at a 15% filling rate, wherein a is example 1, b is example 2, and C is example 3;
FIG. 9 is a graph showing the real part of complex permeability of the Fe-Co alloy/C composite nanofibers prepared in example 1, example 2, and example 3 after being mixed with paraffin wax at a filling rate of 15%;
FIG. 10 is a graph of imaginary part of complex permeability of the Fe-Co alloy/C composite nanofiber prepared in example 1, example 2, example 3 after being mixed with paraffin wax according to a filling rate of 15%;
FIG. 11 is a graph showing the magnetic loss tangent of the Fe-Co alloy/C composite nanofibers obtained in example 1, example 2, and example 3, after being mixed with paraffin wax at a filling rate of 15%;
FIG. 12 is a graph showing the real part of complex dielectric constant of the Fe-Co alloy/C composite nanofibers prepared in example 1, example 2, and example 3, after being mixed with paraffin wax at a filling rate of 15%;
FIG. 13 is a graph showing imaginary parts of complex dielectric constants of the Fe-Co alloy/C composite nanofibers prepared in example 1, example 2, and example 3 after being mixed with paraffin wax at a filling rate of 15%;
FIG. 14 is a dielectric loss tangent chart of the Fe-Co alloy/C composite nanofibers prepared in example 1, example 2, and example 3, after being mixed with paraffin wax at a filling rate of 15%;
FIG. 15 is a graph showing the Cole-Cole plot of the Fe-Co alloy/C composite nanofiber prepared in example 1 mixed with paraffin wax at a 15% loading rate.
Detailed Description
In order to enable those skilled in the art to more clearly understand the technical scheme of the present invention, the technical scheme of the present invention will be described in detail with reference to specific embodiments.
Example 1
First, 1.0g of Polyacrylonitrile (PAN) was dissolved in 9.0g of N, N-Dimethylformamide (DMF), and the mixture was sufficiently dissolved by magnetic stirring at 40 ℃. Then, 0.0015mol of iron acetylacetonate and 0.0015mol of cobalt acetylacetonate were added to the above solution, which was stirred at 40 ℃ to be thoroughly mixed, thereby forming a uniform precursor solution.
The precursor solution was then drawn up using a 20mL syringe and electrospun. Parameters of the electrostatic spinning are set as follows: the voltage is +13kV/-3kV, the liquid pushing speed is 0.04mm/min, and the receiving distance is 15cm. And after the electrostatic spinning is finished, putting the spun nanofiber into a drying oven, drying at 60 ℃ for 24 hours, pre-oxidizing at 240 ℃ for 2 hours, and carbonizing the pre-oxidized sample in a nitrogen atmosphere (keeping the carbonization condition at 800 ℃ for 2 hours) to obtain the Fe-Co alloy/C composite nanofiber.
The Scanning Electron Microscope (SEM) characterization is shown in figure 1, the nanofiber has a three-dimensional cross-linking morphology, the diameter of the fiber is distributed between 100nm and 300nm, and magnetic nanoparticles are uniformly distributed on the surface of the carbon nanofiber in a spherical shape and an irregular shape; as shown in FIG. 4, the Transmission Electron Microscope (TEM) characterization shows that the nearly spherical protrusions on the surface of the carbon nanofiber are of a core-shell structure, and ordered lattice fringes are observed in the surrounding area, wherein the inter-plane distances are 0.342nm and 0.201nm respectively, and the inter-plane distances correspond to the (002) crystal plane of the outer graphite shell and the (110) crystal plane of the inner Fe-Co alloy core respectively.
The Fe-Co alloy/C composite nanofiber and paraffin are mixed according to the filling rate of 15%, a circular ring wave absorber with the outer diameter of 7.00mm and the inner diameter of 3.04mm is pressed on a special die, and the circular ring wave absorber is placed in a clamp to test the wave absorbing performance of the wave absorber. The three-dimensional reflection loss diagram is shown in fig. 5, the maximum reflection loss is-18.66 dB when the thickness of the wave absorber is 1.08mm, and the maximum effective absorption bandwidth is 4.2GHz (13.9-18 GHz) when the thickness of the wave absorber is 1.22 mm.
Example 2
First, 1.0g of Polyacrylonitrile (PAN) was dissolved in 9.0g of N, N-Dimethylformamide (DMF), and the mixture was sufficiently dissolved by magnetic stirring at 40 ℃. Then, 0.00225mol of iron acetylacetonate and 0.00075mol of cobalt acetylacetonate were added to the above solution, which was stirred at 40 ℃ to be thoroughly mixed to form a uniform precursor solution.
The precursor solution was then drawn up using a 20mL syringe and electrospun. Parameters of the electrostatic spinning are set as follows: the voltage is +13kV/-3kV, the liquid pushing speed is 0.04mm/min, and the receiving distance is 15cm. And after the electrostatic spinning is finished, putting the spun nanofiber into a drying oven, drying at 60 ℃ for 24 hours, pre-oxidizing at 240 ℃ for 2 hours, and carbonizing the pre-oxidized sample in a nitrogen atmosphere (keeping the carbonization condition at 800 ℃ for 2 hours) to obtain the Fe-Co alloy/C composite nanofiber.
The Scanning Electron Microscope (SEM) characterization of the nano-fiber is shown in fig. 2, the nano-fiber is in a three-dimensional cross-linked morphology, the diameter of the fiber is distributed between 100nm and 300nm, and the magnetic nano-particles are uniformly distributed on the surface of the carbon nano-fiber in a spherical shape and an irregular shape.
The Fe-Co alloy/C composite nanofiber and paraffin are mixed according to the filling rate of 15%, a circular ring wave absorber with the outer diameter of 7.00mm and the inner diameter of 3.04mm is pressed on a special die, and the circular ring wave absorber is placed in a clamp to test the wave absorbing performance of the wave absorber. The three-dimensional reflection loss diagram is shown in fig. 6, the maximum reflection loss is-50.70 dB when the thickness of the wave absorber is 4.26mm, and the maximum effective absorption bandwidth is 3.4GHz (4.7-6.1 GHz and 15.3-17.1 GHz) when the thickness of the wave absorber is 4.68 mm.
Example 3
First, 1.0g of Polyacrylonitrile (PAN) was dissolved in 9.0g of N, N-Dimethylformamide (DMF), and the mixture was sufficiently dissolved by magnetic stirring at 40 ℃. Then, 0.00075mol of iron acetylacetonate and 0.00225mol of cobalt acetylacetonate were added to the above solution, which was stirred at 40 ℃ to be thoroughly mixed to form a uniform precursor solution.
The precursor solution was then drawn up using a 20mL syringe and electrospun. Parameters of the electrostatic spinning are set as follows: the voltage is +13kV/-3kV, the liquid pushing speed is 0.04mm/min, and the receiving distance is 15cm. And after the electrostatic spinning is finished, putting the spun nanofiber into a drying oven, drying at 60 ℃ for 24 hours, pre-oxidizing at 240 ℃ for 2 hours, and carbonizing the pre-oxidized sample in a nitrogen atmosphere (keeping the carbonization condition at 800 ℃ for 2 hours) to obtain the Fe-Co alloy/C composite nanofiber.
The Scanning Electron Microscope (SEM) characterization of the nano-fiber is shown in fig. 3, the nano-fiber has a three-dimensional cross-linking morphology, but the phenomenon of stacking aggregation occurs, the number of continuous fibers is less, and the magnetic nano-particles are uniformly distributed on the surface of the carbon nano-fiber in a spherical shape and an irregular shape.
The Fe-Co alloy/C composite nanofiber and paraffin are mixed according to the filling rate of 15%, a circular ring wave absorber with the outer diameter of 7.00mm and the inner diameter of 3.04mm is pressed on a special die, and the circular ring wave absorber is placed in a clamp to test the wave absorbing performance of the wave absorber. The three-dimensional reflection loss diagram is shown in fig. 7, the maximum reflection loss is-14.36 dB when the thickness of the wave absorber is 5mm, and the maximum effective absorption bandwidth is 0.8GHz (17.3-18 GHz) when the thickness of the wave absorber is 5.00 mm.
Test example 1:
the decay constant curves of the fe—co alloy/C composite nanofibers prepared in example 1, example 2, and example 3 were obtained by mixing them with paraffin wax at a filling rate of 15%, and the results are shown in fig. 8. The attenuation constant of example 1 is significantly greater than that of examples 2 and 3, indicating the strongest electromagnetic wave attenuation capability when the molar ratio of Fe and Co incorporated is 1:1. Meanwhile, the electromagnetic attenuation characteristic is also described as a main reason for the difference of the wave absorbing performance of each sample.
Test example 2:
to further investigate the mechanism responsible for the electromagnetic attenuation properties, the complex permeability of examples 1, 2, and 3 was compared.
The complex permeability of each sample in the frequency range of 2 to 18GHz was measured by using a vector network analyzer after mixing the fe—co alloy/C composite nanofibers prepared in example 1, example 2, and example 3 with paraffin at a filling rate of 15%, and the results are shown in fig. 9, 10, and 11, wherein fig. 9 is a real part of the complex permeability of each sample, fig. 10 is an imaginary part of the complex permeability of each sample, and fig. 11 is a magnetic loss tangent of each sample. The complex permeability and the positive cutting angle of the high-frequency part (more than 6 GHz) of each sample can show that the magnetic loss of each sample is relatively close, which indicates that the magnetic loss capacity is not quite different, and the magnetic loss is not the main cause of the difference of the wave absorbing performance of each sample.
Test example 3:
to further investigate the mechanism responsible for the electromagnetic attenuation properties, the complex dielectric constants of example 1, example 2, example 3 were compared.
The complex dielectric constants of the respective samples in the frequency range of 2 to 18GHz were measured by using a vector network analyzer after mixing the fe—co alloy/C composite nanofibers prepared in example 1, example 2, and example 3 with paraffin at a filling rate of 15%, and the results are shown in fig. 12, 13, and 14, wherein fig. 12 is a real part of the complex dielectric constant of each sample, fig. 13 is an imaginary part of the complex dielectric constant of each sample, and fig. 14 is a dielectric loss tangent of each sample. Example 1 has the highest real and imaginary dielectric constant values in the test frequency band, which shows to some extent that the sample has a strong capacity to store and consume charges to electromagnetic waves; and example 1 had the highest dielectric loss capacity to some extent by calculating the dielectric loss tangent. While example 3, on the other hand, exhibited the lowest real and imaginary dielectric constant values, probably due to the carbon fibers forming a cluster packing, the three-dimensional network morphology was destroyed, and less conductive network was formed. It can be seen that dielectric loss is a major cause of the difference in the wave-absorbing properties of each sample.
Test example 4:
to further explore the deep mechanisms of dielectric loss in example 1, the loss mechanisms were analyzed using debye theory. The theoretical equation is shown as follows:
wherein ε is s And epsilon ∞ Dielectric constant, ε, of sample under electrostatic field and high frequency, respectively 0 Is the dielectric constant of free space. It is apparent that the graph obtained by the above formula is a semicircle, which is called Cole-Cole graph, as shown in fig. 15. Each polarization relaxation process corresponds to a semicircle, and many semicircles exist in the low frequency part of the Cole-Cole diagram of example 1, which illustrates that the multiple polarization relaxation processes are included: there are many heterogeneous interfaces between Fe-Co alloy particles and interfacial phases, interfacial phases and amorphous carbon, amorphous carbon and paraffin,these interfaces can create many interface polarization losses; meanwhile, the Fe-Co alloy particles damage the graphite lattice to form polarization centers, so that charge distribution is uneven, and dipole polarization is generated. Whereas the high frequency portion of the Cole-Cole plot of example 1 tends to flatten, indicating that the conduction loss is the dominant loss at this time. In summary, dielectric loss is the main cause of the difference in the absorption performance of each sample, wherein the low frequency is the interface polarization and dipole polarization in the dielectric loss, and the high frequency is the conduction loss in the dielectric loss.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The Fe-Co alloy/C composite nanofiber is characterized in that the Fe-Co alloy/C composite nanofiber is in a three-dimensional cross-linked shape, and consists of Fe-Co alloy nanoparticles and carbon nanofibers, wherein the Fe-Co alloy nanoparticles are uniformly distributed on the surfaces of the carbon nanofibers, and the outer sides of the Fe-Co alloy nanoparticles are wrapped with a layer of graphite;
in the Fe-Co alloy nano particles, the molar ratio of Fe to Co is 1-3: 1 to 3.
2. The Fe-Co alloy/C composite nanofiber according to claim 1, wherein the Fe-Co alloy/C composite nanofiber has a diameter distribution of 100nm to 300nm.
3. The Fe-Co alloy/C composite nanofiber according to claim 1, wherein the molar ratio of Fe to Co is 1:1.
4. a method for preparing the Fe-Co alloy/C composite nanofiber according to any one of claims 1 to 3, comprising the steps of:
step 1: dissolving polyacrylonitrile in N, N-dimethylformamide, and heating and stirring to fully dissolve the polyacrylonitrile; then adding ferric acetylacetonate and cobalt acetylacetonate, and continuing heating and stirring to obtain a uniform precursor solution;
step 2: and (3) carrying out electrostatic spinning by using the precursor solution in the step (1), drying and pre-oxidizing the spun nanofiber after the electrostatic spinning is finished, and then carbonizing the pre-oxidized sample in a nitrogen atmosphere to obtain the Fe-Co alloy/C composite nanofiber.
5. The method for preparing Fe-Co alloy/C composite nanofiber according to claim 4, wherein the dosage ratio of polyacrylonitrile, N-dimethylformamide to iron acetylacetonate to cobalt acetylacetonate is 1g:9g:0.003mol.
6. The method for preparing Fe-Co alloy/C composite nanofibers according to claim 4, wherein the parameters of said electrospinning are: the voltage is +13kV/-3kV, the liquid pushing speed is 0.04mm/min, and the receiving distance is 15cm.
7. The method for preparing Fe-Co alloy/C composite nanofibers according to claim 4, wherein the drying conditions of the drying are: drying at 50-100 deg.c for 12-36 hr, preferably at 60 deg.c for 24 hr;
or, pre-oxidizing for 1-3 h at 200-250 ℃;
or, the carbonization condition is kept at 500-1000 ℃ for 1-3 hours, preferably at 800 ℃ for 2 hours.
8. Use of the Fe-Co alloy/C composite nanofiber as claimed in any one of claims 1 to 3 in a wave absorbing material.
9. A wave absorber, characterized in that paraffin is used as a matrix, the Fe-Co alloy/C composite nanofiber according to any one of claims 1-3 is filled in the paraffin, the filling rate is 15%, and the thickness of the wave absorber is 1-5 mm.
The application of Fe-Co alloy in improving dielectric loss of carbon nanofiber wave-absorbing material.
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| CN103422193A (en) * | 2013-08-05 | 2013-12-04 | 江苏科技大学 | Co/C composite nanofiber microwave absorbent, and preparation method and application thereof |
| CN103422192A (en) * | 2013-08-05 | 2013-12-04 | 江苏科技大学 | Fe-Co alloy/C composite nanofiber microwave absorbent, and preparation method and application thereof |
| CN103436994A (en) * | 2013-08-05 | 2013-12-11 | 江苏科技大学 | Fe-Ni alloy/C composite nanofiber microwave absorbent, preparation method and application of absorbent |
| CN103436995A (en) * | 2013-08-05 | 2013-12-11 | 江苏科技大学 | Fe/C composite nanofiber microwave absorbent, preparation method and application of absorbent |
| CN106637507A (en) * | 2016-10-13 | 2017-05-10 | 江苏科技大学 | Magnetic alloy/dielectric oxide composite nanofiber and preparation method thereof, and wave-absorbing coating prepared by adopting nanofiber |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103422193A (en) * | 2013-08-05 | 2013-12-04 | 江苏科技大学 | Co/C composite nanofiber microwave absorbent, and preparation method and application thereof |
| CN103422192A (en) * | 2013-08-05 | 2013-12-04 | 江苏科技大学 | Fe-Co alloy/C composite nanofiber microwave absorbent, and preparation method and application thereof |
| CN103436994A (en) * | 2013-08-05 | 2013-12-11 | 江苏科技大学 | Fe-Ni alloy/C composite nanofiber microwave absorbent, preparation method and application of absorbent |
| CN103436995A (en) * | 2013-08-05 | 2013-12-11 | 江苏科技大学 | Fe/C composite nanofiber microwave absorbent, preparation method and application of absorbent |
| CN106637507A (en) * | 2016-10-13 | 2017-05-10 | 江苏科技大学 | Magnetic alloy/dielectric oxide composite nanofiber and preparation method thereof, and wave-absorbing coating prepared by adopting nanofiber |
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