A nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material, its preparation method and application

Abstract

This invention discloses a nano-(FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material, its preparation method, and its application, belonging to the field of microwave absorbing composite material technology. The (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material prepared using the method provided by this invention has a complete graphene structure and uniform oxide particle size, ranging from 50nm to 300nm, effectively avoiding abnormal oxide grain growth / coarsening. It also possesses advantages such as low thickness, strong microwave absorption capability, and wide absorption bandwidth. At a thickness of 2mm, the minimum reflection loss is -40.6dB, and the absorption bandwidth is 5.4GHz, meeting the application requirements of microwave absorbing coatings. The preparation method is simpler, easier to operate, and suitable for large-scale production. It can provide new ideas for further improving the microwave absorption performance of microwave absorbing materials.

Description

Technical Field

[0001] This invention relates to the field of microwave absorbing composite materials, and in particular to a nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material, its preparation method, and its application. Background Technology

[0002] With the widespread application of electronic devices and wireless communications, electromagnetic pollution has become a serious problem, posing a significant threat to military security, the environment, and human health. Therefore, developing lightweight, thin, strong-absorbing, and wide-bandgap absorbing materials has become crucial. In recent years, research on composite materials has shifted from single electrical or magnetic components to electromagnetic composite materials.

[0003] Currently, the main microwave absorbing materials under in-depth research include ferrites, magnetic metals, and carbon materials. Among them, high-entropy ceramics have attracted widespread attention due to their unique thermodynamic, magnetic, electrical, and dielectric properties. High-entropy ceramics refer to solid solutions composed of five or more components. By adjusting the elemental composition, their magnetic and dielectric properties can be altered, thus affecting their electromagnetic wave absorption capabilities. Among all types of high-entropy ceramics, high-entropy oxides ((FeCoNiCuMn)3O4) are easy to prepare and possess higher stability. Currently, most high-entropy oxide microwave absorbing materials are powder particles. This structure results in a simple loss mechanism, a short electromagnetic wave reflection path, and is not conducive to better electromagnetic wave absorption.

[0004] Refining absorber particles at the micro- and nano-scale in composite materials is one of the effective ways to improve microwave absorption performance. However, previous reports often used traditional tube furnaces or muffle furnaces for heat treatment of high-entropy oxides. This process requires slow heating and cooling, and long-term calcination at high temperatures can easily cause particle agglomeration and damage to the alloy and carbon material structure. Generally, surface diffusion in the low-temperature region plays a major role during sintering, which leads to coarsening. Although the decomposition temperature of graphene in carbon materials is as high as 1000℃ or more, the decomposition temperature decreases in an oxidizing environment, and prolonged high-temperature calcination will damage the graphene structure. Summary of the Invention

[0005] The purpose of this invention is to provide a nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material, its preparation method and application, in order to solve the problem that particle agglomeration and structural damage of alloy and carbon materials are easily caused when the absorbing particles in the microwave absorbing composite material are refined at the micro-nano scale.

[0006] To achieve the above objectives, this invention provides a method for preparing nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material, the steps of which are as follows:

[0007] S1. Dissolve the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer in anhydrous ethanol, add deionized water and ethylene glycol, and stir until completely dissolved.

[0008] S2. Add the graphite oxide paste to deionized water and then ultrasonically disperse the graphite oxide paste.

[0009] S3. Add five metal nitrates and hexamethylenetetramine to the homogeneous solution prepared in step S1, stir until completely dissolved, then add the ultrasonically dispersed graphite oxide paste from step S2, mix well to obtain the precursor solution.

[0010] S4. Place the obtained precursor solution in a polytetrafluoroethylene-lined reactor, heat it to 150-200℃ and keep it at that temperature. After the holding time is over, let it cool naturally to room temperature, wash it and dry it to obtain the precursor powder.

[0011] S5. Place the obtained precursor powder in a Joule furnace and heat it to 800-1000℃ under vacuum conditions and keep it at that temperature.

[0012] Preferably, the volume ratio of anhydrous ethanol:deionized water:ethylene glycol in S1 is 15:10:48, and the mass-volume ratio of polyethylene oxide-polypropylene oxide-polyethylene oxide:anhydrous ethanol is 1:17-19.

[0013] Preferably, the concentration of graphite oxidized paste in S2 is 2 mg / mL, and it is ultrasonically dispersed for 2 hours.

[0014] Preferably, the five metal nitrates in S3 are nitrates of manganese, iron, nickel, copper, and cobalt, and the mass molar ratio of polyethylene oxide-polypropylene oxide-polyethylene oxide to the five metal nitrates is 1g:1mmol.

[0015] Preferably, the five metal nitrates in S3 are Mn(NO3)2·4H2O, Fe(NO3)3·9H2O, Ni(NO3)2·6H2O, Cu(NO3)2·3H2O, and Co(NO3)3·6H2O.

[0016] Preferably, the mass ratio of hexamethylenetetramine: polyethylene oxide-polypropylene oxide-polyethylene oxide is 1:2-3.

[0017] Preferably, the material is kept at 150-200℃ for 15 hours in S4, cooled to room temperature, washed with deionized water and anhydrous ethanol, and then dried at 60-80℃.

[0018] Preferably, in S5, the vacuum condition is -0.8 to 0.93 MPa, the temperature is increased at a rate of 1000-1200℃ / min, and the temperature is held at 800-1000℃ for 6 minutes.

[0019] A nano-high entropy oxide (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material was prepared by the method described above.

[0020] Application of a nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material as described above in the preparation of microwave absorbing coatings.

[0021] The nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material provided by this invention uses spinel-type high-entropy compounds to provide basic magnetic dielectric loss capability, introduces FeNi alloy to increase the material's interface loss and magnetic loss, and loads rGO to improve the material's conductivity and enhance dielectric loss, thereby increasing multiple reflection and scattering capabilities, achieving the effect of synergistic effect of multiple loss mechanisms.

[0022] Therefore, the present invention provides a nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material, its preparation method, and its application, the specific technical effects of which are as follows:

[0023] (1) The (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material prepared by the preparation method provided in this invention has a complete graphene structure and uniform oxide particle size, with particle size ranging from 50nm to 300nm, which effectively avoids abnormal growth of oxide grains / coarsening of oxide particles.

[0024] (2) The (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material prepared by the preparation method provided in this invention has the advantages of low thickness, strong microwave absorption capability and wide absorption bandwidth. The thickness is 2mm, the electromagnetic wave loss is -40.6dB and the absorption bandwidth is 5.4GHz, which can meet the application requirements of microwave absorbing coating.

[0025] (3) The preparation method provided by the present invention is simpler, easier to operate, and suitable for large-scale production; it can provide new ideas for further improving the microwave absorption performance of microwave absorbing materials. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1This is the X-ray diffraction pattern of the nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material prepared in Example 1 of this invention;

[0028] Figure 2 This is a SEM image of the nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material prepared in Example 1 of this invention;

[0029] Figure 3 This is a schematic diagram of the 3D reflection loss of the nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material prepared in Example 1 of this invention;

[0030] Figure 4 This is the X-ray diffraction pattern of the nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material prepared in Example 2 of this invention;

[0031] Figure 5 This is a SEM image of the nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material prepared in Example 2 of this invention;

[0032] Figure 6 A schematic diagram of the 3D reflection loss of the nanoscale (FeCoNiCuMn)3O4-FeNi / rG O composite microwave absorbing material prepared in Example 2 of this invention. Detailed Implementation

[0033] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0034] To make the objectives, technical solutions, and advantages of this application clearer, more thorough, and more complete, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. The following detailed descriptions are all illustrations of embodiments, intended to provide further detailed explanation of the present invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0035] The instruments, equipment, reagents, and materials used in the examples were all obtained commercially.

[0036] Example 1

[0037] The specific steps for preparing a nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material are as follows:

[0038] S11. Accurately weigh 0.6 g of polyethylene oxide-polypropylene oxide-polyethylene oxide (P123) and dissolve it in 11.25 mL of anhydrous ethanol. Then add 5.1 mL of deionized water and 36 mL of ethylene glycol, and stir until completely dissolved. Next, add 150.6 mg Mn(NO3)2·4H2O (0.6 mmol), 242.4 mg Fe(NO3)3·9H2O (0.6 mmol), 174.9 mg Ni(NO3)2·6H2O (0.6 mmol), 144.9 mg Cu(NO3)2·3H2O (0.6 mmol), 174.6 mg Co(NO3)3·6H2O (0.6 mmol), and 0.21 g hexamethylenetetramine, and stir until completely dissolved. Then add 2.4 mL of graphite oxide paste dispersion (ultrasonically dispersed for 2 h, concentration 2 mg / mL).

[0039] S12. Add the solution obtained in step S11 to a 100 mL polytetrafluoroethylene-lined reactor and keep it at 170 °C for 15 h. After the heat preservation is completed, allow it to cool naturally. After cooling to room temperature, wash it alternately with deionized water and anhydrous ethanol until the liquid is clear. Then dry it at 60 °C to obtain the precursor powder.

[0040] S13. Place the obtained precursor powder in a Joule furnace, maintain the vacuum degree in the furnace at -0.9MPa, heat to 900℃ at a heating rate of 1000℃ / min, and hold for 6min to obtain nano (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material.

[0041] X-ray diffraction phase analysis was performed on the obtained nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material, and the results are as follows: Figure 1 As shown, the five characteristic peaks at 30.1°, 35.2°, 42.9°, 56.8°, and 62.4° correspond to the (220), (311), (400), (511), and (440) crystal planes of the spinel structure (PDF#13-0162), respectively. Other phases were identified as FeNi alloy phases, with diffraction peaks at 44.1°, 51.4°, and 75.7°, corresponding to the (111), (200), and (220) crystal planes of the FeNi alloy (PDF#38-0419), respectively. The broad rGO diffraction peak at 23.5° of (FeCoNiCuMn)3O4 is not obvious in the spectrum, possibly due to the high intensity of the alloy diffraction peaks and the low rGO content.

[0042] The obtained nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material was observed using SEM. The SEM images are shown below. Figure 2As shown, the sheet material is graphene, and the white particles distributed on it are high-entropy oxide and FeNi alloy particles, with an average particle size of 50nm-300nm.

[0043] The electromagnetic parameters of the material were tested using a vector network analyzer, and then the material's reflection loss was calculated based on transmission line theory. Finally, Origin software was used to plot the results, as shown below. Figure 3 As shown, the minimum reflection loss at 2.4 mm and 9.8 GHz is -40.6 dB, while the effective absorption bandwidth at 1.68 mm is 5.4 GHz. It has strong reflection loss and wide effective bandwidth near the low thickness of 2 mm, which meets the requirements of low thickness, strong absorption and wide absorption band.

[0044] Depend on Figures 1 to 3 It can be seen that nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material has been successfully prepared.

[0045] Example 2

[0046] The specific steps for preparing a nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material are as follows:

[0047] S21. Accurately weigh 0.6 g of P123 and dissolve it in 11.25 mL of anhydrous ethanol. Add 4.5 mL of deionized water and 36 mL of ethylene glycol. Then, add 147.05 mg Mn(CH3COO)2·4H2O (0.6 mmol), 114.56 mg Fe(OH)(CH3COO)2 (0.6 mmol), 149.45 g (CH3COO)2Co·4H2O (0.6 mmol), 149.38 mg Ni(CH3COO)2·4H2O (0.6 mmol), 119.79 mg Cu(CH3COO)2·H2O (0.6 mmol), and 0.21 g hexamethylenetetramine, and stir until completely dissolved. Then, add 3 mL of graphite oxide paste dispersion (ultrasonicated for 2 hours, concentration 2 mg / mL).

[0048] S22. Add the solution obtained in step S21 to a 100mL reactor and keep it at 170℃ for 15h. After the heat preservation is completed, let it cool naturally. After cooling to room temperature, wash it alternately with deionized water and anhydrous ethanol until the liquid is clear several times. Then dry it at 60℃ to obtain the precursor powder.

[0049] S23. Place the obtained precursor powder in a Joule furnace, maintain the vacuum degree in the furnace at -0.9MPa, heat to 900℃ at a heating rate of 1000℃ / min, and hold for 6min to obtain nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material.

[0050] X-ray diffraction phase analysis was performed on the obtained nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material, and the results are as follows: Figure 4 As shown, the five characteristic peaks at 30.1°, 35.2°, 42.9°, 56.8°, and 62.4° correspond to the (220), (311), (400), (511), and (440) crystal planes of the spinel structure (PDF#13-0162), respectively. Other phases were identified as FeNi alloy phases, with diffraction peaks at 44.1°, 51.4°, and 75.7°, corresponding to the (111), (200), and (220) crystal planes of the FeNi alloy (PDF#38-0419), respectively. The broad rGO diffraction peak at 23.5° of (FeCoNiCuMn)3O4 is not obvious in the spectrum, possibly due to the high intensity of the alloy diffraction peaks and the low rGO content.

[0051] The obtained nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material was observed using SEM. The SEM images are shown below. Figure 5 As shown, the sheet material is graphene, and the white particles distributed on it are oxide particles and alloy particles, distributed on the surface and side edges of the graphene.

[0052] The electromagnetic parameters of the material were tested using a vector network analyzer, and then the material's reflection loss was calculated based on transmission line theory. Finally, Origin software was used to plot the results, as shown below. Figure 6 As shown, the minimum reflection loss at 14.6 GHz is -57.9 dB at 1.64 mm, while the effective absorption bandwidth at 1.58 mm is 5.3 GHz. It has strong reflection loss and wide effective bandwidth near the low thickness of 1.6 mm, which meets the requirements of low thickness, strong absorption and wide absorption band.

[0053] Depend on Figures 4 to 6 It can be seen that nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material has been successfully prepared.

[0054] Therefore, the (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material prepared by the method provided in this invention has a complete graphene structure and uniform oxide particle size, all between 50nm and 300nm, effectively avoiding abnormal growth / coarsening of oxide grains. It also has the advantages of low thickness, strong absorption capacity, and wide absorption bandwidth. With a thickness of 2mm, the electromagnetic wave loss is -40.6dB, and the absorption bandwidth is 5.4GHz, which can meet the application requirements of microwave absorbing coatings. The preparation method is simpler, easier to operate, and suitable for large-scale production. It can provide new ideas for further improving the microwave absorption performance of microwave absorbing materials.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material, characterized in that, The steps are as follows: S1. Dissolve the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer in anhydrous ethanol, add deionized water and ethylene glycol, and stir until completely dissolved. S2. Add the graphite oxide paste to deionized water and then ultrasonically disperse the graphite oxide paste. S3. Add five metal nitrates and hexamethylenetetramine to the homogeneous solution prepared in step S1, stir until completely dissolved, then add the ultrasonically dispersed graphite oxide paste from step S2, mix well to obtain the precursor solution. S4. Place the obtained precursor solution in a polytetrafluoroethylene-lined reactor, heat it to 150-200℃ and keep it at that temperature. After the holding time is over, let it cool naturally to room temperature, wash it and dry it to obtain the precursor powder. S5. Place the obtained precursor powder in a Joule furnace and heat it to 800-1000℃ under vacuum conditions and keep it at that temperature. In S5, the vacuum condition is -0.8 to 0.93 MPa, the temperature is increased at a rate of 1000-1200℃ / min, and then held at 800-1000℃ for 6 minutes.

2. The preparation method of a nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material according to claim 1, characterized in that: In S1, the volume ratio of anhydrous ethanol:deionized water:ethylene glycol is 15:10:48, and the mass-volume ratio of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer:anhydrous ethanol is 1:17-19.

3. The preparation method of a nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material according to claim 1, characterized in that: The concentration of graphite oxide paste in S2 was 2 mg / mL, and it was ultrasonically dispersed for 2 hours.

4. The preparation method of a nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material according to claim 1, characterized in that: S3 contains five metal nitrates: manganese, iron, nickel, copper, and cobalt nitrates. The mass molar ratio of the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer to the five metal nitrates is 1 g: 1 mmol.

5. The preparation method of a nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material according to claim 4, characterized in that: The five metal nitrates in S3 are Mn(NO3)2·4H2O, Fe(NO3)3·9H2O, Ni(NO3)2·6H2O, Cu(NO3)2·3H2O, and Co(NO3)3·6H2O.

6. The preparation method of a nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material according to claim 1, characterized in that: The mass ratio of hexamethylenetetramine to poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer is 1:2-3.

7. The preparation method of a nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material according to claim 1, characterized in that: In S4, keep warm at 150-200℃ for 15 hours, cool to room temperature, wash with deionized water and anhydrous ethanol, and then dry at 60-80℃.

8. A nano-high entropy oxide (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material prepared by the preparation method of the nano-scale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material as described in any one of claims 1-7.

9. The application of the nanoscale (FeCoNiCuMn)3O4-FeNi / rGO composite microwave absorbing material as described in claim 8 in the preparation of microwave absorbing coatings.

Images