Electromagnetic wave-absorbing composite material based on nickel ferrite and preparation method thereof

Abstract

The invention discloses a nickel ferrite-based electromagnetic wave-absorbing composite material and a preparation method thereof, and belongs to the technical field of wave-absorbing materials, nickel ferrite nano porous particles are subjected to carbon heat treatment to obtain heat-treated nickel ferrite matrix powder, and then a two-dimensional molybdenum disulfide nanosheet is loaded on the surface of the heat-treated nickel ferrite matrix powder with a three-dimensional structure to obtain the nickel ferrite-based electromagnetic wave-absorbing composite material. And finally, the nickel ferrite / molybdenum disulfide composite powder is subjected to surface modification through a conductive polymer polyaniline, and the electromagnetic wave-absorbing composite material based on the nickel ferrite can be obtained. The effective bandwidth of the electromagnetic wave-absorbing composite material can reach 9 GHz under the thickness of 2 mm through multi-stage cooperation of oxygen vacancies, sulfur vacancies, conductive coating, heterostructures and other characteristics, and continuous coverage of 8-18 GHz is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wave-absorbing materials, and particularly relates to a nickel ferrite-based electromagnetic wave-absorbing composite material and a preparation method thereof. BACKGROUND

[0002] With the rapid development and large-scale application of electromagnetic wave technology in the fields of high-frequency communication, radar detection, remote sensing navigation, etc., the demand for high-performance electromagnetic wave-absorbing materials is increasing. Electromagnetic wave-absorbing materials can effectively absorb and attenuate external electromagnetic waves, avoid mutual interference between communication lines, improve the electromagnetic compatibility of precision electronic equipment and the stealth survival capability of military equipment, can efficiently prevent and treat electromagnetic pollution, and has great application space in the normal operation of electronic strategic equipment and the encryption of electromagnetic information of communication equipment in military aspects.

[0003] Nickel ferrite (NiFe2O4) is a functional material with an inverse spinel structure, has a "magnetic + dielectric" dual function, and is widely used for preparing electromagnetic wave-absorbing materials. A Chinese patent application with the publication number CN120288840A discloses a lightweight porous nickel ferrite composite electromagnetic absorbing material and a preparation method thereof. The scheme successfully controls the density of the porous electromagnetic absorbing material to be below 2.3 g / cm 3 , and takes into account the light weight and electromagnetic absorbing performance.

[0004] However, the above scheme only relies on the intrinsic polarization of single nickel ferrite (i.e., nickel ferrite) and the weak conductive network formed after carbonization of chitosan, and has no second loss medium, which leads to a serious lack of energy dissipation capability in the medium and high frequency bands, and the effective absorption bandwidth (EAB) is only 1.6-2.8 GHz, which cannot meet the "thin and wide" engineering requirements in the high-frequency communication application scenarios such as 5G / 6G millimeter wave terminals. SUMMARY

[0005] The purpose of the present application is to provide a nickel ferrite-based electromagnetic wave-absorbing composite material and a preparation method thereof. The nickel ferrite is sequentially subjected to carbon thermal treatment, deposition of molybdenum disulfide, and coating of polyaniline, and the prepared nickel ferrite-based electromagnetic wave-absorbing composite material has a wide absorption bandwidth and has the characteristics of "thin, light, wide, and strong", which meets the application requirements in high-frequency communication scenarios.

[0006] The purpose of the present application can be achieved by the following technical solutions: A nickel ferrite-based electromagnetic wave-absorbing composite material is prepared by the following steps: The nickel ferrite nanoporous particles are subjected to carbon heat treatment to obtain a heat-treated nickel ferrite matrix powder, then two-dimensional molybdenum disulfide nanosheets are loaded on the surface of the three-dimensional heat-treated nickel ferrite matrix powder to obtain a nickel ferrite / molybdenum disulfide composite powder, and finally the surface of the nickel ferrite / molybdenum disulfide composite powder is modified by a conductive polymer polyaniline to obtain a nickel ferrite-based electromagnetic wave absorbing composite material.

[0007] Further, the ammonium persulfate solution is prepared from ammonium persulfate and 1 mol / L hydrochloric acid aqueous solution.

[0008] Further, the nickel ferrite / molybdenum disulfide composite powder is prepared by the following steps: ammonium molybdate, thiourea and deionized water are added to a hydrothermal reaction kettle, stirred at 200-300 r / min for 10-15 min, then the heat-treated nickel ferrite matrix powder is added to the hydrothermal reaction kettle, hydrothermal reaction is carried out at 200℃ for 20-24 h, natural cooling to room temperature, centrifugal filtration, the precipitate is washed with deionized water and anhydrous ethanol for 3-5 times respectively, vacuum drying at 60-80℃ to constant weight, the dried product is added to a crucible and transferred to a tube furnace, treated at 600℃ for 1.5-2 h under argon protection, and then naturally cooled to room temperature to obtain the nickel ferrite / molybdenum disulfide composite powder.

[0009] The amount ratio of ammonium molybdate, thiourea, deionized water and heat-treated nickel ferrite matrix powder is 0.6 g:3 g:30 mL:0.05-0.06 g.

[0010] Further, the heat-treated nickel ferrite matrix powder is prepared by the following steps: The nickel ferrite nanoporous particles and activated carbon are added to a marbled mortar in a mass ratio of 5:2-4, and ground for 25-35 min, then the ground mixture is added to a crucible and transferred to a tube furnace, treated at 500℃ for 2.5-3 h under argon protection, then air is introduced and the treatment is continued for 5-6 h, the excess activated carbon is removed, the carbon heat treatment of the nickel ferrite porous particles is completed, and then the mixture is naturally cooled to room temperature to obtain the heat-treated nickel ferrite matrix powder.

[0011] Further, the nickel ferrite nanoporous particles are prepared by the following steps: Nickel nitrate hexahydrate, ferric nitrate nonahydrate, and deionized water were added to a hydrothermal reactor and stirred until dissolved. Then, ethylenediamine was added dropwise, and the mixture was stirred at 300-500 rpm for 10-15 min. Next, a 25% urea aqueous solution was added, and the mixture was stirred for another 20-30 min. The mixture was kept at 180-190℃ for 10-12 h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature, centrifuged, and filtered. The precipitate was washed 3-5 times with deionized water and anhydrous ethanol, respectively, and then vacuum dried at 60-80℃ to constant weight to obtain the nickel ferrite precursor. The nickel ferrite precursor was added to a crucible and transferred to a muffle furnace, where it was calcined at 500-550℃ for 2 h to obtain nickel ferrite nanoporous particles.

[0012] The ratio of the amounts of nickel nitrate hexahydrate, ferric nitrate nonahydrate, deionized water, ethylenediamine, and urea aqueous solution is 1.45g: 4.04g: 500-600mL: 0.12-0.15mL: 20-22mL.

[0013] This invention also provides a method for preparing an electromagnetic absorbing composite material based on nickel ferrite, comprising the following steps: Nickel ferrite / molybdenum disulfide composite powder and a 1 mol / L hydrochloric acid aqueous solution were added to a flask and ultrasonically dispersed for 20-30 min. Then, aniline was added and ultrasonically dispersed for another 20-30 min. The dispersion was then transferred to a reaction vessel, and a 0.5 mol / L ammonium persulfate solution was added dropwise at 0-5℃. After the addition was complete, the reaction was kept at this temperature for 18-20 h. The mixture was centrifuged and filtered, and the precipitate was washed with deionized water until the final wash solution was neutral. The precipitate was then vacuum dried at 60-80℃ to constant weight to obtain the nickel ferrite-based electromagnetic wave absorbing composite material.

[0014] The ratio of nickel ferrite / molybdenum disulfide composite powder, hydrochloric acid aqueous solution, aniline and ammonium persulfate solution is 2g:80mL:0.4g:10mL.

[0015] The beneficial effects of this invention are: 1. The electromagnetic absorbing composite material based on nickel ferrite in this invention has a wide absorption bandwidth. Through multi-level synergy of features such as oxygen vacancies, sulfur vacancies, conductive coating and heterostructure, the effective bandwidth can reach 9GHz with a thickness of 2mm, achieving continuous coverage of 8-18GHz.

[0016] 2. The addition of ethylenediamine during the preparation of nickel ferrite nanoporous particles in this invention can complex metal ions, preventing instantaneous nucleation of nickel ferrite grains and helping to improve the porosity and specific surface area of ​​the nickel ferrite nanoporous particles, which is beneficial for subsequent anchoring of molybdenum disulfide nanosheets. During the calcination and conversion of the nickel ferrite precursor, the particle size of the nickel ferrite nanoporous particles tends to decrease within a temperature range of 500-550℃. By controlling the temperature, the particle size can be kept within a reasonable range.

[0017] 3. The nickel ferrite nanoporous particles of this invention, after carbothermic treatment, can increase the oxygen vacancies in the product, thereby increasing Fe... 3+ / Fe 2+ The number of dipoles is increased, and the doping of molybdenum disulfide nanosheets can increase sulfur vacancies and heterogeneous interfaces, thereby improving the interfacial polarization capability of the material. Finally, conductive polyaniline improves the electromagnetic absorption performance of the electromagnetic absorbing composite material by reducing surface reflection and extending the electron transport path. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1: This example provides an electromagnetic absorbing composite material based on nickel ferrite, which is prepared by the following method: S1: 14.5g nickel nitrate hexahydrate, 40.4g ferric nitrate nonahydrate, and 5L deionized water were added to a hydrothermal reactor and stirred until dissolved. Then, 1.2mL ethylenediamine was added dropwise and stirred at 300r / min for 10min. Then, 200mL of 25% urea aqueous solution was added and stirred for another 20min. The mixture was kept at 180℃ for 10h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature, centrifuged and filtered. The precipitate was washed three times with deionized water and three times with anhydrous ethanol, and dried under vacuum at 60℃ to constant weight to obtain the nickel ferrite precursor. The nickel ferrite precursor was added to a crucible and transferred to a muffle furnace and calcined at 500℃ for 2h to obtain nickel ferrite nanoporous particles with an average particle size of 40.2nm.

[0020] S2: Add 5g of nickel ferrite nanoporous particles and 2g of activated carbon to an agate mortar and grind for 25 minutes. Add the ground mixed powder to a crucible and transfer it to a tube furnace. Under argon protection and heat treatment at 500℃ for 2.5 hours, then introduce air and continue heat treatment for 5 hours to remove excess activated carbon. This completes the carbothermic treatment of the nickel ferrite porous particles. Allow it to cool naturally to room temperature to obtain heat-treated nickel ferrite matrix powder.

[0021] S3: Add 30g ammonium molybdate, 150g thiourea and 1500mL deionized water to a hydrothermal reactor and stir at 200r / min for 10min. Then add 2.5g heat-treated nickel ferrite matrix powder to the hydrothermal reactor and hydrothermally react at 200℃ for 20h. After naturally cooling to room temperature, centrifuge and filter. Wash the precipitate three times with deionized water and anhydrous ethanol respectively. Dry it under vacuum at 60℃ to constant weight. Add the dried product to a crucible and transfer it to a tube furnace. Heat it at 600℃ for 1.5h under argon protection and allow it to cool naturally to room temperature to obtain nickel ferrite / molybdenum disulfide composite powder.

[0022] S4: Add 2g of nickel ferrite / molybdenum disulfide composite powder and 80mL of 1mol / L hydrochloric acid aqueous solution to a flask, and sonicate for 20min. Then add 0.4g of aniline and continue sonication for 20min. Then transfer the dispersion to a reaction vessel and add 10mL of 0.5mol / L ammonium persulfate solution (ammonium persulfate solution is prepared by mixing ammonium persulfate and 1mol / L hydrochloric acid aqueous solution) dropwise at 0℃. After the addition is complete, keep the reaction at the temperature for 18h, centrifuge and filter, wash the precipitate with deionized water until the last wash is neutral, and vacuum dry at 60℃ to constant weight to obtain the electromagnetic wave absorbing composite material based on nickel ferrite.

[0023] Example 2: This example provides an electromagnetic absorbing composite material based on nickel ferrite, which is prepared by the following method: S1: 14.5g of nickel nitrate hexahydrate, 40.4g of ferric nitrate nonahydrate, and 5.5L of deionized water were added to a hydrothermal reactor and stirred until dissolved. Then, 1.35mL of ethylenediamine was added dropwise and stirred at 400r / min for 12.5min. Then, 210mL of urea aqueous solution with a mass fraction of 25% was added and stirred for another 25min. The mixture was kept at 185℃ for 11h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature, centrifuged and filtered. The precipitate was washed four times with deionized water and four times with anhydrous ethanol, and dried under vacuum at 70℃ to constant weight to obtain the nickel ferrite precursor. The nickel ferrite precursor was added to a crucible and transferred to a muffle furnace and calcined at 525℃ for 2h to obtain nickel ferrite nanoporous particles with an average particle size of 41.6nm.

[0024] S2: Add 5g of nickel ferrite nanoporous particles and 3g of activated carbon to an agate mortar and grind for 30 minutes. Add the ground mixed powder to a crucible and transfer it to a tube furnace. Under argon protection and heat treatment at 500℃ for 2.75 hours, then introduce air and continue heat treatment for 5.5 hours to remove excess activated carbon. The carbon heat treatment of the nickel ferrite porous particles is completed. Allow it to cool naturally to room temperature to obtain heat-treated nickel ferrite matrix powder.

[0025] S3: Add 30g ammonium molybdate, 150g thiourea and 1500mL deionized water to a hydrothermal reactor and stir at 250r / min for 12.5min. Then add 2.75g heat-treated nickel ferrite matrix powder to the hydrothermal reactor and hydrothermally react at 200℃ for 22h. After naturally cooling to room temperature, centrifuge and filter. Wash the precipitate four times with deionized water and anhydrous ethanol, respectively. Dry it under vacuum at 70℃ to constant weight. Add the dried product to a crucible and transfer it to a tube furnace. Heat it under argon protection and at 600℃ for 1.75h. After naturally cooling to room temperature, obtain nickel ferrite / molybdenum disulfide composite powder.

[0026] S4: Add 2g of nickel ferrite / molybdenum disulfide composite powder and 80mL of 1mol / L hydrochloric acid aqueous solution to a flask, and sonicate for 25min. Then add 0.4g of aniline and continue sonication for 25min. Then transfer the dispersion to a reaction vessel and add 10mL of 0.5mol / L ammonium persulfate solution (ammonium persulfate solution is prepared by mixing ammonium persulfate and 1mol / L hydrochloric acid aqueous solution) dropwise at 2.5℃. After the addition is complete, keep the reaction at the temperature for 19h, centrifuge and filter, wash the precipitate with deionized water until the last wash is neutral, and vacuum dry at 70℃ to constant weight to obtain the electromagnetic wave absorbing composite material based on nickel ferrite.

[0027] Example 3: This example provides an electromagnetic absorbing composite material based on nickel ferrite, which is prepared by the following method: S1: 14.5g of nickel nitrate hexahydrate, 40.4g of ferric nitrate nonahydrate, and 6L of deionized water were added to a hydrothermal reactor and stirred until dissolved. Then, 1.5mL of ethylenediamine was added dropwise and stirred at 500r / min for 15min. Then, 220mL of urea aqueous solution with a mass fraction of 25% was added and stirred for another 30min. The mixture was kept at 190℃ for 12h. After the reaction was completed, the mixture was naturally cooled to room temperature, centrifuged and filtered. The precipitate was washed five times with deionized water and five times with anhydrous ethanol, and dried under vacuum at 80℃ to constant weight to obtain the nickel ferrite precursor. The nickel ferrite precursor was added to a crucible and transferred to a muffle furnace and calcined at 550℃ for 2h to obtain nickel ferrite nanoporous particles with an average particle size of 42.6nm.

[0028] S2: Add 5g of nickel ferrite nanoporous particles and 4g of activated carbon to an agate mortar and grind for 35 minutes. Add the ground mixed powder to a crucible and transfer it to a tube furnace. Under argon protection and heat treatment at 500℃ for 3 hours, then introduce air and continue heat treatment for 6 hours to remove excess activated carbon. This completes the carbothermic treatment of the nickel ferrite porous particles. Allow it to cool naturally to room temperature to obtain heat-treated nickel ferrite matrix powder.

[0029] S3: Add 30g ammonium molybdate, 150g thiourea and 1500mL deionized water to a hydrothermal reactor and stir at 300r / min for 15min. Then add 3g heat-treated nickel ferrite matrix powder to the hydrothermal reactor and hydrothermally react at 200℃ for 24h. After naturally cooling to room temperature, centrifuge and filter. Wash the precipitate five times with deionized water and anhydrous ethanol, respectively. Dry it under vacuum at 80℃ to constant weight. Add the dried product to a crucible and transfer it to a tube furnace. Heat it under argon protection and at 600℃ for 2h. After naturally cooling to room temperature, obtain nickel ferrite / molybdenum disulfide composite powder.

[0030] S4: Add 2g of nickel ferrite / molybdenum disulfide composite powder and 80mL of 1mol / L hydrochloric acid aqueous solution to a flask, and sonicate for 30min. Then add 0.4g of aniline and continue sonication for 30min. Then transfer the dispersion to a reaction vessel and add 10mL of 0.5mol / L ammonium persulfate solution (ammonium persulfate solution is prepared by mixing ammonium persulfate and 1mol / L hydrochloric acid aqueous solution) dropwise at 5℃. After the addition is complete, keep the reaction at the temperature for 20h, centrifuge and filter, wash the precipitate with deionized water until the last wash is neutral, and vacuum dry at 80℃ to constant weight to obtain the electromagnetic wave absorbing composite material based on nickel ferrite.

[0031] The activated carbon used in this example was SC-2, with a particle size of 200 mesh, and branded by Nanjing Chuhai. All other raw materials were commercially available.

[0032] Comparative Example 1: The difference from Example 3 is that step S2 is omitted. In step S3, the heat-treated nickel ferrite matrix powder is replaced with an equal mass of nickel ferrite nanoporous particles from step S1. Subsequent steps remain unchanged to prepare an electromagnetic wave absorbing composite material.

[0033] Comparative Example 2: The difference from Example 3 is that step S3 is omitted, and in step S4, the nickel ferrite / molybdenum disulfide composite powder is replaced with an equal mass of heat-treated nickel ferrite matrix powder in step S2. Subsequent steps remain unchanged, and an electromagnetic absorbing composite material is prepared.

[0034] Comparative Example 3: The difference from Example 3 is that the nickel ferrite / molybdenum disulfide composite powder in step S3 is used directly as the electromagnetic wave absorbing composite material without the treatment in step S4.

[0035] Comparative Example 4: The difference from Example 3 is that ethylenediamine is not added in step S1, while the other steps remain unchanged, and an electromagnetic wave absorbing composite material is prepared.

[0036] The absorption performance of each electromagnetic absorbing composite material in the 218 GHz test range at a thickness of 2 mm was tested using a vector network analyzer (VNA, Agilent N5230A, USA). The results are shown in Table 1. Table 1. Electromagnetic absorption performance results of various electromagnetic absorbing composite materials. As can be seen from Table 1, the electromagnetic wave absorbing composite materials in Examples 1-3 have an effective bandwidth of about 9 GHz with a thickness of 2 mm, and the peak reflection loss is < -50 dB. In addition, the composite materials have a porous structure and meet the engineering specifications of "thin, light, wide and strong".

[0037] The electromagnetic absorbing composite material in Comparative Example 1 did not undergo carbothermal treatment during preparation, resulting in a shallower reflection loss peak. This may be due to a decrease in oxygen vacancy concentration, leading to a reduction in Fe... 3+ / Fe 2+ The sharp decrease in the number of dipoles indicates that the increase in oxygen vacancies can improve the electromagnetic wave absorption performance of the material.

[0038] The electromagnetic wave absorbing composite material in Comparative Example 2 has the shallowest reflection loss peak and almost fails below 10 GHz. This may be because it lacks the doping of molybdenum disulfide nanosheets, loses the MoS2 / NiFe2O4 heterostructure, and the interface polarization disappears. This indicates that adding sulfur vacancies and increasing the heterostructure can improve the magnetic loss of the material.

[0039] In Comparative Example 3, the peak reflection loss was shallower due to the absence of conductive polyaniline deposition. This may be because the high concentration of free electrons on the material surface led to impedance mismatch, resulting in a decrease in the absorption effect of the incident wave. This indicates that conductive polyaniline can improve the absorption performance of the material by reducing surface reflection and extending the electron transport path.

[0040] The reduced absorption effect of the electromagnetic wave absorbing composite material in Comparative Example 4 is due to the lack of complexation by ethylenediamine, which leads to instantaneous nucleation of nickel ferrite grains, a decrease in porosity and specific surface area, and an inability to uniformly anchor molybdenum disulfide nanosheets.

[0041] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0042] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A method for preparing a nickel ferrite-based electromagnetic wave absorbing composite material, characterized in that, It comprises the following steps: The nickel ferrite nanoporous particles are subjected to carbon heat treatment to obtain a heat-treated nickel ferrite matrix powder, then two-dimensional molybdenum disulfide nanosheets are loaded on the surface of the three-dimensional heat-treated nickel ferrite matrix powder to obtain a nickel ferrite / molybdenum disulfide composite powder, and finally the surface of the composite powder is modified by a conductive polymer polyaniline to obtain a nickel ferrite-based electromagnetic wave-absorbing composite material.

2. The preparation method of the electromagnetic wave absorbing composite material based on nickel ferrite according to claim 1, characterized in that, The nickel ferrite nanoporous particles are prepared by the following steps: Nickel nitrate hexahydrate, iron nitrate nonahydrate and deionized water are added to a hydrothermal reaction kettle, stirred and dissolved, then ethylenediamine is added dropwise, stirred at 300-500 r / min for 10-15 min, then a 25% mass fraction urea aqueous solution is added, and stirring is continued for 20-30 min, and then the reaction is kept at 180-190 DEG C for 10-12 h, after the reaction is completed, the reaction kettle is naturally cooled to room temperature, centrifugal filtration is performed, the precipitate is washed with deionized water and anhydrous ethanol for 3-5 times respectively, and vacuum drying is performed at 60-80 DEG C until the weight is constant, to obtain a nickel ferrite precursor; the nickel ferrite precursor is added to a crucible and transferred to a muffle furnace, calcined at 500-550 DEG C for 2 h, to obtain nickel ferrite nanoporous particles.

3. The method for preparing an electromagnetic absorbing composite material based on nickel ferrite according to claim 2, characterized in that, The amount ratio of the nickel nitrate hexahydrate, iron nitrate nonahydrate, deionized water, ethylenediamine and urea aqueous solution is 1.45 g:4.04 g:500-600 mL:0.12-0.15 mL:20-22 mL.

4. The preparation method of the electromagnetic wave absorbing composite material based on nickel ferrite according to claim 1, characterized in that, The heat-treated nickel ferrite matrix powder is prepared by the following steps: The nickel ferrite nanoporous particles and activated carbon are added to a marbled mortar in a mass ratio of 5:2-4, and grinding is performed for 25-35 min, the ground mixture is added to a crucible and transferred to a tube furnace, and heat treatment is performed at 500 DEG C under argon protection for 2.5-3 h, then air is introduced and heat treatment is continued for 5-6 h, the excess activated carbon is removed, the carbon heat treatment of the nickel ferrite porous particles is completed, and natural cooling is performed to room temperature, to obtain a heat-treated nickel ferrite matrix powder.

5. The method for preparing an electromagnetic absorbing composite material based on nickel ferrite according to claim 1, characterized in that, The nickel ferrite / molybdenum disulfide composite powder is prepared by the following steps: ammonium molybdate, thiourea and deionized water are added to a hydrothermal reaction kettle, stirred at 200-300 r / min for 10-15 min, then the heat-treated nickel ferrite matrix powder is added to the hydrothermal reaction kettle, and hydrothermal reaction is performed at 200 DEG C for 20-24 h, and then natural cooling is performed to room temperature, centrifugal filtration is performed, the precipitate is washed, dried, transferred to a tube furnace, and heat treatment is performed at 600 DEG C under argon protection for 1.5-2 h, and then natural cooling is performed to room temperature, to obtain a nickel ferrite / molybdenum disulfide composite powder.

6. The method for preparing an electromagnetic absorbing composite material based on nickel ferrite according to claim 5, characterized in that, The amount ratio of the ammonium molybdate, thiourea, deionized water and heat-treated nickel ferrite matrix powder is 0.6 g:3 g:30 mL:0.05-0.06 g.

7. The method for preparing an electromagnetic absorbing composite material based on nickel ferrite according to claim 1, characterized in that, The specific preparation method of the nickel ferrite-based electromagnetic wave-absorbing composite material is as follows: The nickel ferrite / molybdenum disulfide composite powder and an aqueous hydrochloric acid solution with a concentration of 1 mol / L are added into a flask, ultrasonic dispersion is carried out for 20-30 min, then aniline is added, ultrasonic dispersion is continued for 20-30 min, then the dispersion liquid is transferred into a reaction kettle, an ammonium persulfate solution with a concentration of 0.5 mol / L is added dropwise at 0-5°C, after the dropwise addition is completed, reaction is carried out for 18-20 h, centrifugal filtration is carried out, the precipitate is washed with deionized water until the last washing liquid is neutral, vacuum drying is carried out at 60-80°C until the constant weight is obtained, and a nickel ferrite-based electromagnetic wave-absorbing composite material is obtained.

8. The method for preparing an electromagnetic absorbing composite material based on nickel ferrite according to claim 7, characterized in that, The use amount ratio of the nickel ferrite / molybdenum disulfide composite powder, the aqueous hydrochloric acid solution, the aniline and the ammonium persulfate solution is 2 g:80 mL:0.4 g:10 mL.

9. The method for preparing an electromagnetic absorbing composite material based on nickel ferrite according to claim 7, characterized in that, The ammonium persulfate solution is prepared from ammonium persulfate and an aqueous hydrochloric acid solution with a concentration of 1 mol / L.

10. A nickel ferrite-based electromagnetic wave absorbing composite material, characterized by, The electromagnetic wave-absorbing composite material is prepared by the preparation method in any one of claims 1-9.

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