Electromagnetic wave absorption composite material with microflower structure and preparation method of electromagnetic wave absorption composite material
By preparing C/ZnO/Fe7Co3 electromagnetic wave absorbing materials with micron flower structures, the problems of low absorption efficiency and narrow frequency response range of existing LDH-derived carbon-based composite materials in the high-frequency band were solved, achieving lightweight, wide-bandwidth, and highly efficient electromagnetic wave absorption.
Patent Information
- Application Number
- CN202610284185.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-10
- Publication Date
- 2026-05-15
AI Technical Summary
Existing LDH-derived carbon-based composite materials suffer from problems such as low absorption efficiency, difficulty in synergistic impedance matching and attenuation capabilities, low precision in microstructure control, and complex preparation processes in high-frequency electromagnetic wave absorption, which limit their practical applications.
By preparing C/ZnO/Fe7Co3 electromagnetic wave absorbing materials with micron flower structures, and using a multi-element LDH derivatization strategy to precisely control the ratio of Fe and Co, a carbon-based composite material with adjustable phase composition and hierarchical structure is constructed, forming an amorphous carbon-coated heterogeneous interface structure of ZnO and Fe7Co3. High-temperature heat treatment is then used to form a porous structure to optimize impedance matching and attenuation capabilities.
The material achieves lightweight, wide-bandwidth, and highly efficient electromagnetic wave absorption. It exhibits excellent absorption performance in the high-frequency band, capable of absorbing more than 99.9999% of electromagnetic waves and covering the 11.44-18.00GHz frequency band. This solves the problems of low absorption efficiency and narrow frequency response range of existing materials in the high-frequency band.
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Figure CN122054555A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of carbon-based composite electromagnetic wave absorbing materials, and in particular to an electromagnetic wave absorbing composite material with a micron flower structure and its preparation method. Background Technology
[0002] With the rapid development of wireless communication technology and electronic devices, the widespread application of high-frequency electromagnetic waves (such as the Ku band 12-18GHz) has brought about electromagnetic interference and pollution problems, necessitating the development of high-performance electromagnetic wave absorbing materials to ensure stable equipment operation and information security. Traditional absorbing materials (such as ferrites and magnetic metals) perform well in the low-frequency band, but suffer from poor impedance matching and insufficient attenuation in high-frequency environments, making it difficult to meet the comprehensive requirements of being "thin, lightweight, wide-bandwidth, and strong." Therefore, designing novel composite materials that combine lightweight, wide-bandwidth, and strong absorption characteristics has become a current research hotspot.
[0003] In recent years, carbon-based composites derived from layered hydrogen hydroxide (LDH) have shown significant application potential in the field of electromagnetic wave absorption due to their tunable layered structure, high specific surface area, and synergistic effects among multiple components. Composite materials containing metal oxides, alloys, and carbon can be obtained through high-temperature pyrolysis of multi-component LDH precursors. The advantages of multi-component LDH-derived carbon-based composites lie in the tunable metal elements in the laminations, the designability of intercalated anions, and the structural diversity of the pyrolysis products. By rationally selecting metal types, controlling the proportion of lamination elements, and optimizing heat treatment conditions, the synergistic optimization of the material's wave absorption performance can be achieved. Simultaneously, the layered or derived porous structure retained after pyrolysis can effectively extend the electromagnetic wave propagation path and enhance energy dissipation efficiency. Furthermore, the abundant heterogeneous interfaces and structural defects between metal oxides, alloys, and carbon phases can promote interfacial polarization and dipole polarization behavior, further enhancing the material's electromagnetic wave attenuation capability.
[0004] However, current LDH-derived absorbing materials still face three main bottlenecks in practical applications: First, absorption efficiency is limited, and impedance matching and attenuation capabilities are difficult to coordinate, resulting in a narrow frequency response range and difficulty in full-band compatibility. Second, the precision of heterogeneous interface modulation is low, and traditional methods are insufficient to achieve precise construction of microstructures, leading to poor performance repeatability. Third, the fabrication process is complex; the intrinsic absorption performance of LDH is weak, relying on energy-intensive and complex derivation processes, and lacking environmental friendliness and stability, thus restricting its industrial application. Therefore, how to improve the precision of interface modulation while simultaneously simplifying material preparation and ensuring structural performance stability has become a key issue in promoting the practical application of this type of material. Summary of the Invention
[0005] To address the aforementioned problems, this invention proposes an electromagnetic wave absorbing composite material with a micron-flower structure and its preparation method, which solves the difficulties in controlling the phase composition and microstructure of multi-component LDH-derived carbon-based composite materials, as well as the problem of low high-frequency electromagnetic wave absorption efficiency.
[0006] This invention can be achieved through the following technical solutions: A method for preparing an electromagnetic wave absorbing composite material with a micron-flower structure includes the following steps: Step 1: Mix the raw materials ferric nitrate nonahydrate, cobalt nitrate hexahydrate, zinc nitrate hexahydrate, glucose, urea and polyvinylpyrrolidone in deionized water until homogeneous, and transfer the mixed solution to a reaction vessel for hydrothermal reaction. Step 2: The mixture after the hydrothermal reaction is repeatedly centrifuged and washed, and then freeze-dried to obtain a black FeCoZn-LDH precursor; Step 3: Place the FeCoZn-LDH precursor in a ceramic crucible and perform high-temperature heat treatment in a tube furnace. After cooling, obtain an electromagnetic wave absorbing composite material with a micron flower structure.
[0007] Preferably, in step 1, the molar ratio of ferric nitrate nonahydrate, cobalt nitrate hexahydrate, zinc nitrate hexahydrate, glucose, urea and polyvinylpyrrolidone is (0-2.1):(0-0.9):3:4:5.5:0.0025.
[0008] Preferably, the hydrothermal reaction temperature in step 1 is 160-200℃, and the reaction time is 6-24h.
[0009] Preferably, the washing in step 2 involves alternating washing with anhydrous ethanol and ultrapure water 4-6 times.
[0010] Preferably, in step 2, centrifugation is performed in a high-speed centrifuge at 8000-10000 rpm for 3-5 minutes.
[0011] Preferably, in step 2, the freeze drying is performed in a freeze dryer at a pressure of 1-10 MPa and a temperature of -80 to -40°C for 36-72 hours.
[0012] Preferably, in step 3, the heat treatment temperature is 600-800℃, the holding time is 2-4h, the heating rate is 3-5℃ / min, and the heat treatment atmosphere is argon.
[0013] The beneficial effects of this invention are: This invention prepares a C / ZnO / Fe7Co3 electromagnetic wave absorbing material with a micron-flower structure. Through a multi-element LDH derivatization strategy, the Fe and Co ratios were precisely controlled, successfully constructing a carbon-based composite material with tunable phase composition and hierarchical structure. The synergistic effect of Fe and Co not only promotes the formation of the Fe7Co3 alloy phase and dominates the phase transformation kinetics, but also guides a significant evolution of the microstructure from an initial willow-leaf-shaped petal to a multi-level stacked hexagonal petal shape. Simultaneously, high-temperature heat treatment forms an amorphous carbon-coated heterogeneous interface structure of ZnO and Fe7Co3, accompanied by the generation of numerous defects and pores. This unique composition and structure synergistically optimizes the material's impedance matching and attenuation capabilities, enabling it to exhibit excellent high-frequency electromagnetic wave absorption characteristics. It holds promise as a next-generation lightweight, broadband, and strongly absorbing LDH-derived carbon-based microwave absorbing material. Attached Figure Description
[0014] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 The XRD pattern of the electromagnetic wave absorbing composite material; Figure 2 SEM image of a composite material that absorbs electromagnetic waves; Figure 3 TEM image of a composite material that absorbs electromagnetic waves; Figure 4 A schematic diagram of electromagnetic wave absorption and reflection loss of electromagnetic wave absorbing composite materials. Detailed Implementation
[0015] The following provides a detailed description of the embodiments of the present invention: These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and processes. However, the scope of protection of the present invention is not limited to the following embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions.
[0016] In Examples 1-4 below, the contents of ferric nitrate nonahydrate and cobalt nitrate hexahydrate are not 0 mmol.
[0017] Example 1: A method for preparing an electromagnetic wave absorbing composite material with a micron-flower structure, comprising the following steps: Step 1: Mix 0.35 mmol ferric nitrate nonahydrate, 0.15 mmol cobalt nitrate hexahydrate, 3 mmol zinc nitrate hexahydrate, 4 mmol glucose, 5.5 mmol urea and 0.0025 mmol polyvinylpyrrolidone in 40 mL of deionized water until homogeneous. Transfer the mixture to a 160 °C reactor for hydrothermal reaction for 24 h. Step 2: Wash the mixture after hydrothermal reaction with anhydrous ethanol and ultrapure water alternately 4 times, centrifuge repeatedly (8000 rpm for 5 min), and then dry it in a freeze dryer at 1 MPa pressure and -80℃ for 72 h to obtain black FeCoZn-LDH precursor. Step 3: Place the FeCoZn-LDH precursor in a ceramic crucible and heat it to 600℃ at a heating rate of 3℃ / min. Heat it in a tube furnace with argon for 4 hours. After cooling, obtain the electromagnetic wave absorbing composite material with a micron flower structure.
[0018] Example 2: A method for preparing an electromagnetic wave absorbing composite material with a micron-flower structure, comprising the following steps: Step 1: Mix 0.7 mmol ferric nitrate nonahydrate, 0.3 mmol cobalt nitrate hexahydrate, 3 mmol zinc nitrate hexahydrate, 4 mmol glucose, 5.5 mmol urea and 0.0025 mmol polyvinylpyrrolidone in 50 mL of deionized water until homogeneous. Transfer the mixture to a 180 °C reactor for hydrothermal reaction for 12 h. Step 2: Wash the mixture after hydrothermal reaction with anhydrous ethanol and ultrapure water alternately 5 times, centrifuge repeatedly (9000 rpm for 4 min), and then dry it in a freeze dryer at 5 MPa pressure and -60℃ for 54 h to obtain black FeCoZn-LDH precursor. Step 3: Place the FeCoZn-LDH precursor in a ceramic crucible and heat it to 700℃ at a heating rate of 4℃ / min. Heat it in a tube furnace with argon for 3 hours. After cooling, obtain the electromagnetic wave absorbing composite material with a micron flower structure.
[0019] Example 3: A method for preparing an electromagnetic wave absorbing composite material with a micron-flower structure, comprising the following steps: Step 1: Mix 1.4 mmol ferric nitrate nonahydrate, 0.6 mmol cobalt nitrate hexahydrate, 3 mmol zinc nitrate hexahydrate, 4 mmol glucose, 5.5 mmol urea and 0.0025 mmol polyvinylpyrrolidone in 40 mL of deionized water until homogeneous. Transfer the mixture to a 190 °C reactor for hydrothermal reaction for 18 h. Step 2: Wash the mixture after hydrothermal reaction with anhydrous ethanol and ultrapure water 6 times alternately, centrifuge repeatedly (10000 rpm for 5 min), and then dry it in a freeze dryer at 10 MPa pressure and -40℃ for 72 h to obtain black FeCoZn-LDH precursor. Step 3: Place the FeCoZn-LDH precursor in a ceramic crucible and heat it to 800℃ at a heating rate of 5℃ / min. Heat it in a tube furnace with argon for 4 hours. After cooling, obtain the electromagnetic wave absorbing composite material with a micron flower structure.
[0020] Example 4: A method for preparing an electromagnetic wave absorbing composite material with a micron-flower structure, comprising the following steps: Step 1: Mix 2.1 mmol ferric nitrate nonahydrate, 0.9 mmol cobalt nitrate hexahydrate, 3 mmol zinc nitrate hexahydrate, 4 mmol glucose, 5.5 mmol urea and 0.0025 mmol polyvinylpyrrolidone in 60 mL of deionized water until homogeneous. Transfer the mixture to a 200 °C reactor for hydrothermal reaction for 24 h. Step 2: Wash the mixture after hydrothermal reaction with anhydrous ethanol and ultrapure water alternately 4 times, centrifuge repeatedly (10000 rpm for 5 min), and then dry it in a freeze dryer at 10 MPa pressure and -80℃ for 72 h to obtain black FeCoZn-LDH precursor. Step 3: Place the FeCoZn-LDH precursor in a ceramic crucible and heat it to 600℃ at a heating rate of 4℃ / min. Heat it in a tube furnace with argon for 4 hours. After cooling, obtain the electromagnetic wave absorbing composite material with a micron flower structure.
[0021] Comparative Example 1: The difference between this comparative example and Example 1 is that ferric nitrate nonahydrate is not added. Cobalt nitrate hexahydrate.
[0022] A method for preparing an electromagnetic wave absorbing composite material with a micron-flower structure includes the following steps: Step 1: Mix 3 mmol zinc nitrate hexahydrate, 4 mmol glucose, 5.5 mmol urea and 0.0025 mmol polyvinylpyrrolidone in 40 mL of deionized water until homogeneous. Transfer the mixture to a 160 °C reactor for hydrothermal reaction for 24 h. Step 2: Wash the mixture after hydrothermal reaction with anhydrous ethanol and ultrapure water alternately 4 times, centrifuge repeatedly (8000 rpm for 5 min), and then dry it in a freeze dryer at 1 MPa pressure and -80℃ for 72 h to obtain black FeCoZn-LDH precursor. Step 3: Place the FeCoZn-LDH precursor in a ceramic crucible and heat it to 600℃ at a heating rate of 3℃ / min. Heat it in a tube furnace with argon for 4 hours. After cooling, obtain the electromagnetic wave absorbing composite material with a micron flower structure.
[0023] Performance testing The electromagnetic wave absorbing composite materials prepared in Examples 1-4 and Comparative Example 1 were subjected to phase composition analysis, microstructure and structural analysis, and electromagnetic wave absorption performance testing. The sample names are shown in Table 1, and the test results are as follows: Figures 1-4 As shown.
[0024] The C / ZnO / Fe7Co3 electromagnetic wave absorbing material with a micron flower structure prepared by this invention has the following XRD pattern: Figure 1 As shown, the diffraction peak of sample CZ corresponds only to pure ZnO; while in the other four samples, diffraction peaks of both ZnO and Fe7Co3 alloy were observed simultaneously. Comparing the diffraction peak intensities of the five LDH pyrolysis products, it can be seen that as the content of Fe3+ and Co2+ in the raw materials increases, the relative content of ZnO decreases sequentially, while the relative content of Fe7Co3 alloy gradually increases. This demonstrates that the phase composition of multi-component LDH-derived carbon-based composite materials can be precisely controlled by changing the content of metal ions in the precursor.
[0025] The C / ZnO / Fe7Co3 electromagnetic wave absorbing material with a micron flower structure prepared by this invention has the following SEM image: Figure 2 As shown, graph a represents CZ, graph b represents CZFC-0.5, and so on, the same applies below. From Figure 2 It can be seen that the C / ZnO / Fe7Co3 composite materials all exhibit a flower-like microstructure: the petals are mainly composed of a large number of microporous nanosheets surrounding the central point, assembled in a "hierarchically stacked and interconnected" manner to form a six-petaled flower morphology. From CZ to CZFC-1, the nanosheets gradually grow larger, and the morphology gradually evolves into a hexagonal star-shaped flower, with the petals also gradually becoming wider and thicker from slender and regular. From CZFC-1 to CZFC-3, the flower size gradually tends to stabilize, and with the increase of Fe7Co3 content, the number of nanoparticles on the surface of the petals and in the gaps between the layers increases, until some areas of CZFC-3 show aggregation or more dense secondary structures. This demonstrates that this method can accurately control the morphological changes of multi-component LDH-derived carbon-based composite materials.
[0026] The C / ZnO / Fe7Co3 electromagnetic wave absorbing material with a micron flower structure prepared by this invention has the following TEM image: Figure 3 As shown, Figure a is the TEM image of the CZFC-2 sample, and Figure b is the HRTEM image of the area within the black box in Figure a. From... Figure 3 It can be seen that both ZnO and Fe7Co3 alloys are uniformly dispersed in the amorphous carbon matrix as nanoparticles, jointly constructing the supporting framework of the petal structure. This type of microstructure can form abundant heterogeneous interfaces, providing favorable conditions for the rapid dissipation of electromagnetic wave energy. This demonstrates that this method can control the microstructure of multi-component LDH-derived carbon-based composite materials.
[0027] The electromagnetic wave absorbing material with a micron-flower structure prepared by this invention has the following electromagnetic wave absorption and reflection loss diagram at a doping ratio of 25 wt%: Figure 4 As shown, from Figure 4 It can be seen that as the Fe7Co3 content increases, the absorption performance of the composite material first increases and then decreases, with CZFC-2 showing the best performance. At a thickness of 3.62 mm, it achieves a minimum reflection loss of -66.87 dB, capable of absorbing over 99.9999% of incident electromagnetic waves; at a thickness of 2.36 mm, it achieves an effective absorption bandwidth of 6.56 GHz, covering the 11.44-18.00 GHz frequency band, realizing complete absorption of high-frequency electromagnetic waves. This demonstrates that the C / ZnO / Fe7Co3 composite material exhibits highly efficient absorption performance for high-frequency electromagnetic waves.
[0028] Table 1 Sample Name Correspondence Table
[0029] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A method for preparing an electromagnetic wave absorbing composite material with a micron-flower structure, characterized in that, Includes the following steps: Step 1: Mix the raw materials ferric nitrate nonahydrate, cobalt nitrate hexahydrate, zinc nitrate hexahydrate, glucose, urea and polyvinylpyrrolidone in deionized water until homogeneous, and transfer the mixed solution to a reaction vessel for hydrothermal reaction. Step 2: The mixture after the hydrothermal reaction is repeatedly centrifuged and washed, and then freeze-dried to obtain a black FeCoZn-LDH precursor; Step 3: Place the FeCoZn-LDH precursor in a ceramic crucible and perform high-temperature heat treatment in a tube furnace. After cooling, obtain an electromagnetic wave absorbing composite material with a micron flower structure.
2. The method for preparing the electromagnetic wave absorbing composite material with a micron-flower structure according to claim 1, characterized in that, In step 1, the molar ratio of ferric nitrate nonahydrate, cobalt nitrate hexahydrate, zinc nitrate hexahydrate, glucose, urea, and polyvinylpyrrolidone is (0-2.1):(0-0.9):3:4:5.5:0.0025.
3. The method for preparing the electromagnetic wave absorbing composite material with a micron-flower structure according to claim 1, characterized in that, In step 1, the hydrothermal reaction temperature is 160-200℃ and the reaction time is 6-24h.
4. The method for preparing the electromagnetic wave absorbing composite material with a micron-flower structure according to claim 1, characterized in that, The washing in step 2 involves alternating between anhydrous ethanol and ultrapure water for 4-6 times.
5. The method for preparing the electromagnetic wave absorbing composite material with a micron-flower structure according to claim 1, characterized in that, In step 2, centrifugation is performed in a high-speed centrifuge at 8000-10000 rpm for 3-5 minutes.
6. The method for preparing the electromagnetic wave absorbing composite material with a micron-flower structure according to claim 1, characterized in that, In step 2, freeze drying is performed in a freeze dryer at a pressure of 1-10 MPa and a temperature of -80 to -40°C for 36-72 hours.
7. The method for preparing the electromagnetic wave absorbing composite material with a micron-flower structure according to claim 1, characterized in that, In step 3, the heat treatment temperature is 600-800℃, the holding time is 2-4h, the heating rate is 3-5℃ / min, and the heat treatment atmosphere is argon.