Magnetic foam structure composite material and preparation method and application thereof

Abstract

The application discloses a kind of magnetic foam structure composite material and its preparation method and application, belong to heat-conducting-wave-absorbing multifunctional material preparation technical field.The in-situ bubble assisted annealing process disclosed in the application is to dissolve iron nitrate, nickel acetate and polyvinylpyrrolidone in deionized water to obtain a mixed solution, then dry the solution to a viscous state, then place the viscous liquid in a tube furnace, pass inert gas and perform high-temperature annealing treatment to obtain the product.The application is simple to operate, has strong repeatability, low production cost, short cycle, is green and environmentally friendly, and can be prepared on a large scale.It can also prepare a series of magnetic foam structure composites by changing the feeding ratio and annealing temperature.The obtained magnetic foam has adjustable composition, texture, high thermal conductivity and wideband microwave absorption characteristics, and has good industrial application potential in heat management, microwave absorption and other fields.

Description

Technical Field

[0001] This invention belongs to the field of magnetic materials technology, and relates to a method for preparing a porous magnetic foam composite material and its application in microwave absorbing and thermally conductive materials. Background Technology

[0002] Porous carbon foam is a type of carbon material with a three-dimensional porous structure. It possesses characteristics such as high specific surface area, tunable pore size, low electrical resistance, low cost, low density, and unique microstructure, making it widely used in ion exchangers, pollutant separation and removal, catalysts, bioanalysis and diagnostics, membranes, and directed transport. It has been reported that the presence of pores in carbon foam not only reduces bulk density but also improves impedance matching of the absorber, which is beneficial for enhancing electromagnetic wave absorption. Furthermore, carbon foam can improve dielectric loss by introducing multiple polarization processes; therefore, combining carbon foam with other magnetic nanoparticles can enhance the electromagnetic wave absorption capacity of the composite material.

[0003] Common methods for preparing porous carbon materials include template method, activation method, deposition method and sintering method. Among them, Chinese patent CN116199220A discloses a method for preparing porous carbon. This method involves uniformly mixing large-pore porous carbon, resin monomers, and solvents, heating and reacting them to obtain a composite hydrogel, then drying the composite hydrogel and finally carbonizing it at high temperature to obtain porous carbon. This method is simple to operate and has a short process flow, but the resin monomers used in this method are formaldehyde and resorcinol, which are prone to causing pollution. Chinese patent CN115020121A discloses a method for preparing porous carbon. This method has a lengthy preparation process, requiring multiple extractions and filtrations, which is complex and generates a large amount of waste liquid. Chinese patent CN112028052B discloses a method for preparing metal-doped porous carbon. This method involves mixing walnut powder, urea, o-phenylenediamine, and potassium hydroxide and ball milling them. The resulting mixture is then treated at high temperature, and the product is washed with hydrochloric acid and distilled water. Finally, the product is mixed with metal salts and dispersants and calcined at high temperature to obtain metal-doped porous carbon material. However, this method is time-consuming, cumbersome, and has excessively thick pore walls and uneven pore size distribution.

[0004] Therefore, how to develop a magnetic foam composite material with high specific surface area and excellent performance that is easy to process, easy to industrialize, and has controllable morphology and size is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the purpose of this invention is to address the problems existing in the prior art by providing a magnetic foam structural composite material and its preparation method that is simple to process, dimensionally controllable, low in cost, and environmentally friendly.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] The primary technical objective of this invention is to provide a magnetic foam structure composite material. This magnetic foam structure composite material is prepared from magnetic nanoparticles and amorphous carbon using an in-situ bubble-assisted annealing process. It is supported by a three-dimensional amorphous carbon framework, and the magnetic nanoparticles (Fe, Fe...) are... 3-y Ni y O4 or Fe 1-x Ni x Three-dimensional porous foam structure modified with Ni;

[0008] The magnetic foam composite material is Fe / Fe 3-y Ni y O4 / C or Fe 3-y Ni y O4 / Fe 1-x Ni x / C or Fe 1-x Ni x / C or Ni / C composite; the magnetic foam composite material has a pore size of 0.62–19.92 μm; and the magnetic nanoparticles have a particle size of 15.12–1300 nm, an amorphous carbon atom content of 30.49–65.19%, an O atom content of 1.83–19.09%, an Fe atom content of 0–44.97%, a Ni atom content of 0–60.34%, and a specific surface area of ​​18.62–201.71 m². 2 / g.

[0009] Preferably, the in-situ bubble-assisted annealing process specifically involves dissolving ferric nitrate, nickel acetate, and polyvinylpyrrolidone in deionized water to obtain a mixed solution, then transferring the solution to an oven to dry it to a viscous state, and finally placing the viscous liquid in a tube furnace, introducing inert gas, and performing high-temperature annealing treatment to obtain the magnetic foam structure composite material.

[0010] It should be noted that this invention utilizes bubbles (NO2, O2, H2O) generated by the decomposition of metal salts as porous templates to assist in the carbonization of polyvinylpyrrolidone. The in-situ bubble-assisted annealing process of the magnetic foam structure composite material disclosed herein is not only simple to operate, highly repeatable, low in production cost, and short in cycle, but also allows for the preparation of a series of magnetic foam structure composite materials by changing the feed ratio and annealing temperature. The pore size of the magnetic foam structure composite material is 0.62–19.92 μm; and the particle size of the magnetic nanoparticles is 15.12–1300 nm. Furthermore, due to the multiple relaxation polarization and good impedance matching of this magnetic foam structure composite material, it exhibits great potential in the field of microwave absorption.

[0011] Furthermore, the magnetic foam composite material prepared according to this invention has excellent microwave absorption characteristics and thermal conductivity. The maximum effective bandwidth of the reflectivity less than or equal to -10dB is 3.04 to 12.4 GHz, the maximum absorption is -18.61 to -48.72dB, the thickness is 1.3 to 2.8 mm, and when mixed with silicone oil at a filling ratio of 30%, the thermal conductivity is 3.36 W / m·K to 3.75 W / m·K.

[0012] The second technical objective of this invention is to provide a method for preparing magnetic foam structural composite materials that is simple to operate, environmentally friendly, and suitable for industrial production.

[0013] To achieve the above objectives, the present invention adopts the following technical solution:

[0014] A method for preparing a magnetic foam structure composite material, the method specifically includes the following steps:

[0015] (1) Weigh a certain mass of ferric nitrate and nickel acetate according to the stoichiometric ratio, mix and dissolve in deionized water, add polyvinylpyrrolidone and stir thoroughly until completely dissolved to form a homogeneous solution;

[0016] (2) The homogeneous solution is transferred to an oven and dried to obtain a viscous liquid;

[0017] (3) The viscous liquid is then placed in a tube furnace, inert gas is introduced, and high-temperature annealing is performed to obtain the magnetic foam structure composite material.

[0018] By adopting the above technical solution, the beneficial effects of the present invention are as follows:

[0019] The preparation method disclosed in this invention is simple to operate and highly reproducible, overcoming the shortcomings of previous preparation processes such as harsh reaction conditions, difficulty in controlling the morphology of reaction products, poor experimental repeatability, and high production costs, and has good potential for industrial application.

[0020] Preferably, the stoichiometric ratio of ferric nitrate and nickel acetate in step (1) is 1:0 to 0:1; and the mass ratio of the total mass of ferric nitrate and nickel acetate to the mass of polyvinylpyrrolidone and deionized water is (2.02 to 1.454):1:30.

[0021] Furthermore, the mass of polyvinylpyrrolidone is 1g.

[0022] Preferably, the drying temperature of the oven in step (2) is 50-80°C and the drying time is 4-8 hours.

[0023] Preferably, the annealing process parameters in step (3) are: annealing temperature 600℃~800℃, heating rate 5℃ / min, annealing time 2h; gas flow rate 0.01~0.05L / min.

[0024] Furthermore, the ark in step (3) is a high-temperature resistant corundum ark, and the inert gas is argon or nitrogen.

[0025] The third technical objective of this invention is to provide the application of the above-mentioned porous magnetic foam composite material in the field of microwave absorption and thermal conductive materials.

[0026] As can be seen from the above technical solution, compared with the prior art, the present invention provides a magnetic foam structure composite material, its preparation method and application, which has the following superior effects:

[0027] 1) This invention is the first to employ an in-situ bubble-assisted annealing process to prepare a magnetic foam structure composite material assembled from amorphous carbon and composite magnetic nanoparticles. This composite material is characterized by its porosity and large specific surface area, and its composition, crystallinity, and grain size are adjustable.

[0028] 2) This invention discloses for the first time the use of magnetic foam composite material as thermally conductive and microwave-absorbing filler. This composite material has adjustable electrical and magnetic properties, excellent thermal conductivity and microwave absorption properties, which are significantly better than other magnetic foam materials reported in the current literature, and show great potential in the field of thermal conductivity and microwave absorption.

[0029] 3) The in-situ bubble-assisted annealing process for preparing magnetic foam composite materials described in this invention is simple to operate, has good controllability, and can adjust the composition, crystallinity, and grain size simply by changing the feed ratio and annealing temperature. Furthermore, the raw materials are inexpensive and readily available, the process is time-efficient, energy-saving, and environmentally friendly, with good repeatability, low requirements for instrument precision, and considerable yield, demonstrating excellent potential for industrial application.

[0030] Therefore, in summary, the magnetic foam structural composite material and its preparation method disclosed in this invention have great market promotion and application value. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0032] Figures 1-4 These are the phase composition and morphology, EDX, XRD, and absorption properties of the product obtained in Example 1 of this invention as measured under a scanning electron microscope.

[0033] Figures 5-8 These are the phase composition and morphology, EDX, XRD, and absorption properties of the product obtained in Example 2 of this invention as measured under a scanning electron microscope.

[0034] Figures 9-12 These are the phase composition and morphology, EDX, XRD, and absorption properties of the product obtained in Example 3 of this invention as measured under a scanning electron microscope.

[0035] Figures 13-16 These are the phase and morphology, EDX, XRD, and absorption properties of the product obtained in Example 4 of this invention as measured under a scanning electron microscope.

[0036] Figures 17-20 These are the phase composition and morphology, EDX, XRD, and absorption properties of the product obtained in Example 5 of this invention as measured under a scanning electron microscope.

[0037] Figures 21-24 These are the phase composition and morphology, EDX, XRD, and absorption properties of the product obtained in Example 6 of this invention as measured under a scanning electron microscope.

[0038] Figures 25-28 These are the phase composition and morphology, EDX, XRD, and absorption properties of the product obtained in Example 7 of this invention as measured under a scanning electron microscope.

[0039] Figures 29-32 These are the phase composition and morphology, EDX, XRD, and absorption properties of the product obtained in Example 8 of this invention as measured under a scanning electron microscope.

[0040] Figures 33-36 These are the phase composition and morphology, EDX, XRD, and absorption properties of the product obtained in Example 9 of this invention as measured under a scanning electron microscope. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] This invention discloses a method for preparing a magnetic foam structure composite material that is simple to process, has controllable dimensions, and exhibits good thermal conductivity and microwave absorption characteristics.

[0043] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0044] Example 1

[0045] A magnetic foam structure Fe / Fe 3-y Ni y The preparation method of O4 / C composite material specifically includes the following steps:

[0046] 2.02 g Fe(NO3)3·9H2O, 0 g Ni(CH3COO)2·4H2O (molar ratio 1:0) and 1 g polyvinylpyrrolidone were dissolved in 30 mL of deionized water and stirred at 25 °C to form a homogeneous solution. The solution was then placed in an oven and dried at 80 °C for 4 h to obtain a viscous liquid. The viscous liquid was loaded into a boat and placed in a tube furnace. It was annealed at 700 °C (heating rate of 5 °C / min) and under a high-purity argon atmosphere with a gas flow rate of 0.03 L / min for 2 h. After natural cooling to room temperature, a magnetic foam structure Fe / Fe3O4 / C composite material was obtained.

[0047] The phase composition and morphology of the obtained product as measured by scanning electron microscopy, and the EDX and XRD results are as follows: Figures 1-3 As shown in the figure. The above analysis indicates that the product is a magnetic foam structure Fe / Fe. 3-y Ni y The O4 / C composite material has a particle size of 45.61 nm to 180 nm, a pore size of 3.10 μm to 7.49 μm, a carbon atomic percentage of 45.75%, an iron atomic percentage of 44.97%, and a specific surface area of ​​102.01 m². 2 g -1 .

[0048] As shown in Tables 1 and 2, the obtained magnetic foam structure Fe / Fe 3-y Ni y O4 / C composite material has excellent microwave absorption characteristics and thermal conductivity. When mixed with paraffin at a filling ratio of 50%, the maximum effective bandwidth with a reflectivity of less than or equal to -10dB is 11.44GHz, the maximum absorption is -25.39dB when the thickness is 2.3mm, and the thermal conductivity is 3.36W / m·K when mixed with silicone oil at a filling ratio of 30%.

[0049] Example 2

[0050] A magnetic foam structure Fe 3-y Ni y O4 / Fe 1-x Ni x The preparation method of the / C composite material, with other conditions unchanged, is based on Example 1, but the feeding ratio is changed. The mass of polyvinylpyrrolidone is fixed at 1g, and the mass of Fe(NO3)3·9H2O is changed to 1.8181g and the mass of Ni(CH3COO)2·4H2O is changed to 0.1453g, that is, the molar ratio of iron to nickel is 9:1.

[0051] The phases, composition, and morphology of the obtained products as measured by XRD, EDX, and scanning electron microscopy are as follows: Figures 5-7 As shown in the figure. From the above analysis, it can be seen that the product is a magnetic foam structure Fe. 3-y Ni y O4 / Fe 1-x Ni x The C / Fe composite material has a particle size of 33.05 nm to 156.2 nm, a pore size of 1.96 μm to 10.41 μm, a C atomic percentage of 50.95%, an Fe atomic percentage of 27%, a Ni atomic percentage of 2.96%, and a specific surface area of ​​48.24 m². 2 g -1 .

[0052] As shown in Tables 1 and 2, the obtained magnetic foam structure Fe 3-y Ni y O4 / Fe 1-x Ni x / C composite material has excellent microwave absorption characteristics and thermal conductivity. When mixed with paraffin at a filling ratio of 50%, the maximum effective bandwidth with a reflectivity of less than or equal to -10dB is 8.44GHz, the thickness is 2.8mm, and the maximum absorption is -39.98dB. When mixed with silicone oil at a filling ratio of 30%, the thermal conductivity is 3.58W / m·K.

[0053] Example 3

[0054] A magnetic foam structure Fe 3-y Ni y O4 / Fe 1-x Ni x The preparation method of the / C composite material, with other conditions unchanged, is based on Example 1, but the feeding ratio is changed. The mass of polyvinylpyrrolidone is fixed at 1g, and the mass of Fe(NO3)3·9H2O is changed to 1.4141g and the mass of Ni(CH3COO)2·4H2O is changed to 0.4362g, that is, the molar ratio of iron to nickel is 7:3.

[0055] The phase composition, morphology, and other properties of the obtained product as measured by XRD, EDX, and scanning electron microscopy are as follows: Figures 9-11 As shown in the figure. The above analysis indicates that the product is a magnetic foam structure of Fe. 3-y Ni y O4 / Fe 1-x Ni x The C / Fe composite material has a particle size of 33.17 nm to 109.17 nm, a pore size of 0.62 μm to 1.65 μm, a C atomic percentage of 65.19%, an Fe atomic percentage of 21.97%, a Ni atomic percentage of 8.18%, and a specific surface area of ​​41.90 m².2 g -1 .

[0056] As shown in Tables 1 and 2, the obtained magnetic foam structure Fe 3-y Ni y O4 / Fe 1-x Ni x / C composite material has excellent microwave absorption characteristics and thermal conductivity. When mixed with paraffin at a filling ratio of 50%, the maximum effective bandwidth with a reflectivity of less than or equal to -10dB is 5.12GHz, and the maximum absorption is -18.61dB when the thickness is 1.5mm. When mixed with silicone oil at a filling ratio of 30%, the thermal conductivity is 3.59W / m·K.

[0057] Example 4

[0058] A magnetic foam structure Fe 3-y Ni y O4 / Fe 1-x Ni x The preparation method of the / C composite material, with other conditions unchanged, is based on Example 1, but the feeding ratio is changed. The mass of polyvinylpyrrolidone is fixed at 1g, and the mass of Fe(NO3)3·9H2O is changed to 1.010g and the mass of Ni(CH3COO)2·4H2O is changed to 0.727g, that is, the molar ratio of iron to nickel is 5:5.

[0059] The phase composition, morphology, and other properties of the obtained product as measured by XRD, EDX, and scanning electron microscopy are as follows: Figures 13-15 As shown in the figure. The above analysis indicates that the product is a magnetic foam structure of Fe. 3-y Ni y O4 / Fe 1-x Ni x The C / Fe composite material has a particle size of 36.94 nm to 101.04 nm, a pore size of 4.19 μm to 19.92 μm, a C atomic percentage of 55.96%, an Fe atomic percentage of 18.35%, a Ni atomic percentage of 21.03%, and a specific surface area of ​​201.71 m². 2 g -1 .

[0060] As shown in Tables 1 and 2, the obtained magnetic foam structure Fe 3-y Ni y O4 / Fe 1-x Ni x / C composite material has excellent microwave absorption characteristics and thermal conductivity. When mixed with paraffin at a filling ratio of 50%, the maximum effective bandwidth with a reflectivity of less than or equal to -10dB is 8.08GHz, the maximum absorption is -26.33dB when the thickness is 2.2mm, and the thermal conductivity is 3.63W / m·K when mixed with silicone oil at a filling ratio of 30%.

[0061] Example 5

[0062] A magnetic foam structure Fe 1-x Ni x The preparation method of the / C composite material, with other conditions unchanged, is based on Example 1, but the feeding ratio is changed. The mass of polyvinylpyrrolidone is fixed at 1g, and the mass of Fe(NO3)3·9H2O is changed to 0.606g and the mass of Ni(CH3COO)2·4H2O is changed to 1.0178g, that is, the molar ratio of iron to nickel is 3:7.

[0063] The phase composition, morphology, and other properties of the obtained product as measured by XRD, EDX, and scanning electron microscopy are as follows: Figures 17-19 As shown in the figure. The above analysis indicates that the product is a magnetic foam structure of Fe. 1-x Ni x The C / Fe composite material has a particle size of 15.12 nm to 42.25 nm, a pore size of 1.64 μm to 6.28 μm, a C atomic percentage of 53.17%, an Fe atomic percentage of 10.78%, a Ni atomic percentage of 34.22%, and a specific surface area of ​​200.40 m². 2 g -1 .

[0064] As shown in Tables 1 and 2, the obtained magnetic foam structure Fe 1-x Ni x / C composite material has excellent microwave absorption characteristics and thermal conductivity. When mixed with paraffin at a filling ratio of 50%, the maximum effective bandwidth with a reflectivity of less than or equal to -10dB is 12.4GHz, the maximum absorption is -48.72dB when the thickness is 2.4mm, and the thermal conductivity is 3.47W / m·K when mixed with silicone oil at a filling ratio of 30%.

[0065] Example 6

[0066] A magnetic Fe 1-x Ni x The preparation method of the / C composite material, with other conditions unchanged, is based on Example 1, but the feeding ratio is changed. The mass of polyvinylpyrrolidone is fixed at 1g, and the mass of Fe(NO3)3·9H2O is changed to 0.202g and the mass of Ni(CH3COO)2·4H2O is changed to 1.3086g, that is, the molar ratio of iron to nickel is 1:9.

[0067] The phase composition, morphology, and other properties of the obtained product as measured by XRD, EDX, and scanning electron microscopy are as follows: Figures 21-23 As shown in the figure. From the above analysis, it can be seen that the product is magnetic Fe. 1-x Ni x The composite material has a particle size of 21.56 nm to 79.72 nm, a carbon atomic percentage of 30.49%, an iron atomic percentage of 8.6%, a nickel atomic percentage of 58.45%, and a specific surface area of ​​59.09 m². 2 g -1 .

[0068] As shown in Tables 1 and 2, the obtained magnetic Fe 1-x Ni x / C composite material has excellent microwave absorption characteristics and thermal conductivity. When mixed with paraffin at a filling ratio of 50%, the maximum effective bandwidth with a reflectivity of less than or equal to -10dB is 3.04GHz, the maximum absorption is -26.85dB when the thickness is 1.3mm, and the thermal conductivity is 3.60W / m·K when mixed with silicone oil at a filling ratio of 30%.

[0069] Example 7

[0070] A method for preparing a magnetic Ni / C composite material, with other conditions unchanged, by changing the feeding ratio based on Example 1, fixing the mass of polyvinylpyrrolidone at 1g, changing the mass of Fe(NO3)3·9H2O to 0g, and the mass of Ni(CH3COO)2·4H2O to 1.454g, that is, the molar ratio of iron to nickel is 0:1.

[0071] The phase composition, morphology, and other properties of the obtained product as measured by XRD, EDX, and scanning electron microscopy are as follows: Figures 25-27 As shown in the figure. The above analysis indicates that the product is a magnetic Ni / C composite material with a particle size of 200 nm to 1300 nm, a C atomic percentage of 37.48%, an Fe atomic percentage of 0%, a Ni atomic percentage of 60.34%, and a specific surface area of ​​139.2 m². 2 g -1 .

[0072] As shown in Tables 1 and 2, the obtained magnetic Ni / C composite material has excellent microwave absorption characteristics and thermal conductivity. When mixed with paraffin at a filling ratio of 50%, the maximum effective bandwidth with a reflectivity of less than or equal to -10dB is 7.44GHz, the thickness is 2.3mm, and the maximum absorption is -23.23dB. When mixed with silicone oil at a filling ratio of 30%, the thermal conductivity is 3.75W / m·K.

[0073] Example 8

[0074] A magnetic Fe 3-yNi y O4 / Fe 1-x Ni x The preparation method of / C composite material, with other conditions unchanged, is based on Example 5, but the annealing temperature of the tube furnace is changed to 600°C.

[0075] The phase composition, morphology, and other properties of the obtained product as measured by XRD, EDX, and scanning electron microscopy are as follows: Figures 29-31 As shown in the figure. From the above analysis, it can be seen that the product is magnetic Fe. 3-y Ni y O4 / Fe 1-x Ni x The composite material has a particle size of 27.09 nm to 79.39 nm, a carbon atomic percentage of 43.92%, an iron atomic percentage of 18.19%, a nickel atomic percentage of 35.39%, and a specific surface area of ​​159.76 m². 2 g -1 .

[0076] As shown in Table 1, the obtained magnetic Fe 3-y Ni y O4 / Fe 1-x Ni x / C composite material has excellent microwave absorption characteristics. When mixed with paraffin at a filling ratio of 50%, the maximum effective bandwidth with a reflectivity of less than or equal to -10dB is 7.68GHz, the thickness is 2.6mm, and the maximum absorption is -43.51dB.

[0077] Example 9

[0078] A magnetic foam structure Fe 1-x Ni x The preparation method of / C composite material, with other conditions unchanged, is based on Example 5, but the annealing temperature of the tube furnace is changed to 800°C.

[0079] The phase composition, morphology, and other properties of the obtained product as measured by XRD, EDX, and scanning electron microscopy are as follows: Figures 33-35 As shown in the figure. The above analysis indicates that the product is a magnetic foam structure of Fe. 1-x Ni x The / C composite material has a particle size of 56.47 nm to 150.29 nm, a pore size of 1.69 μm to 4.95 μm, a C atomic percentage of 64.42%, an Fe atomic percentage of 8.62%, a Ni atomic percentage of 22.57%, and a specific surface area of ​​18.62 m². 2 g -1 .

[0080] As shown in Table 1, the obtained magnetic foam structure Fe 1-x Ni x / C composite material has excellent microwave absorption characteristics. When mixed with paraffin at a filling ratio of 50%, the maximum effective bandwidth with a reflectivity of less than or equal to -10dB is 7.6GHz, the thickness is 2.4mm, and the maximum absorption is -23.11dB.

[0081] Comparative Example 1

[0082] Comparative Example 1 is a porous carbon material prepared according to the reference (Z. Wu, Z. Meng, C. Yao, Y. Deng, G. Zhang, Rice husk derived hierarchical porous carbon with lightweight and efficient microwave absorption. Materials Chemistry and Physics, 2022, 275: 125246.). As shown in Table 1, when the filling ratio with paraffin is 10%, the maximum effective bandwidth with a reflectivity of less than or equal to -10 dB is 3.40 GHz, the thickness is 2.8 mm, and the maximum absorption is -47.46 dB.

[0083] Comparative Example 2

[0084] Comparative Example 2 is a silicon carbide / porous melamine-derived carbon foam composite material prepared according to the reference (X. Ye, Z. Chen, S. Ai, B. Hou, J. Zhang, X. Liang, Q. Zhou, H. Liu, S. Cui, Synthesis and microwave absorption properties of novelreticulation SiC / Porous melamine-derived carbon foam. Journal of Alloys and Compounds, 2019, 791: 883-891.). As shown in Table 1, when mixed with paraffin, the maximum effective bandwidth with a reflectivity of less than or equal to -10 dB is 1.5 GHz, the thickness is 1.15 mm, and the maximum absorption is -25.93 dB.

[0085] Comparative Example 3

[0086] Comparative Example 3 is a graphitic porous carbon material prepared according to the reference (X. Zhu, Q. Wang, S. Kang, J. Lid, X. Jia, Coal-based ultrathin-wall graphitic porous carbon for high-performance form-stable phasechange materials with enhanced thermal conductivity, Chemical Engineering Journal, 2020, 395: 125112.). As shown in Table 2, when mixed with paraffin and filled at a ratio of 90%, the thermal conductivity is 0.58 W / m·K.

[0087] Comparative Example 4

[0088] Comparative Example 4 is derived from the reference (L. Xing, Y. Chen, Y. Yang, C. He, T. Wu, H. Xia, K. Shen, G. Tong, W. Wu, Incorporation of Fe x O y Porous three-dimensional interconnected carbon nanofibers / Fe nanofibers were prepared by integrating nanoparticles into 3D interlinked porous carbon nanofiber networks to synergistically enhance the electrical insulation, electromagnetic wave absorbing / shielding performance, and thermal conductivity. (Chemical Engineering Journal, 2023: 143952.) x O y Composite material. As shown in Table 2, when mixed with silicone oil at a filling ratio of 30%, the thermal conductivity is 3.22 W / m·K.

[0089] Table 1. Microwave absorption properties of the products obtained in Examples 1-21 of this invention.

[0090]

[0091] Table 2 Thermal conductivity of the products obtained in the embodiments of the present invention

[0092]

[0093] Analysis of the above data shows that combining magnetic metals such as iron, nickel, or iron-nickel alloys with porous carbon can improve the thermal conductivity and microwave absorption properties of the material. Specifically, Fe / Fe... 3-y Ni y O4 / C composite material, Fe 3-y Ni y O4 / Fe 1-x Ni x / C composite materials and Fe 1-x Ni x Both Fe / C and Ni / C composite materials showed significant improvements in microwave absorption performance compared to Comparative Example 1 and Comparative Example 2. 3-y Ni y O4 / C composite material, Fe 3-y Ni y O4 / Fe 1-x Ni x / C composite materials and Fe 1-x Ni x The thermal conductivity of both the Ni / C composite material and the Ni / C composite material is significantly improved compared to Comparative Example 3 and Comparative Example 4.

[0094] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A magnetic foam structure composite material, characterized by, The magnetic foam structure composite is a composite of magnetic nanoparticles and amorphous carbon prepared by an in-situ bubble assisted annealing process; the magnetic foam structure composite is Fe / Fe 3-y Ni y O4 / C, Fe 3-y Ni y O4 / Fe 1-x Ni x / C, Fe 1-x Ni x / C or Ni / C composite is supported by a three-dimensional amorphous carbon skeleton, and magnetic nanoparticles Fe, Fe 3-y Ni y O4, Fe 1-x Ni x or Ni modified three-dimensional porous foam structure; wherein, The magnetic foam structure composite has a pore size of 0.62-19.92 μm, and the magnetic nanoparticles have a particle size of 15.12-1300 nm, an amorphous carbon atom ratio of 30.49-65.19%, a Fe atom ratio of 0-44.97%, a Ni atom ratio of 2.96-60.34%, and a specific surface area of 18.62-201.71 m 2 / g. The in-situ bubble assisted annealing process is operated as follows: Iron nitrate, nickel acetate and polyvinylpyrrolidone are dissolved to obtain a mixed solution, and then the solution is dried to a viscous state; the viscous liquid is subjected to high-temperature annealing treatment, and the bubbles generated by the decomposition of metal salts are used as a porous template to assist the carbonization of polyvinylpyrrolidone, thereby obtaining the magnetic foam structure composite material.

2. A method of making the magnetic foam structure composite of claim 1, wherein, The method specifically comprises the following steps: (1) Iron nitrate and nickel acetate are mixed and dissolved in deionized water according to the stoichiometric ratio, and polyvinylpyrrolidone is added and stirred until all are dissolved to form a uniform solution; (2) The uniform solution is dried to obtain a viscous liquid; (3) The viscous liquid is annealed at high temperature in an inert atmosphere to obtain the magnetic foam structure composite material.

3. A method of making a magnetic foam structure composite according to claim 2, wherein, In step (1), the stoichiometric ratio of iron nitrate and nickel acetate is 1:0~0:1; and the mass ratio of the total mass of iron nitrate and nickel acetate to polyvinylpyrrolidone and deionized water is (2.02~1.454):1:

30.

4. The method for preparing a magnetic foam structure composite material according to claim 2, characterized in that, The drying temperature in step (2) is 50~80℃, and the drying time is 4~8 h.

5. The method for preparing a magnetic foam structure composite material according to claim 2, characterized in that, The high-temperature annealing process in step (3) is as follows: The annealing temperature is 600 ℃~800 ℃, the heating rate is 5 ℃ / min, the annealing time is 2 h, high-purity argon or nitrogen is used for protection, and the gas flow rate is 0.01~0.05 L / min.

6. The magnetic foam structure composite material of claim 1 or the magnetic foam structure composite material prepared by the method of any one of claims 3~5 for use in the field of microwave absorption.

7. Use according to claim 6, characterized in that, Also includes: The application of the magnetic foam structure composite material in heat-conducting materials.

Images