Wave-absorbing material and preparation method thereof

Abstract

The invention provides a wave-absorbing material and a preparation method thereof. According to the preparation method, a precursor containing nickel and iron elements is firstly prepared in situ, and then the magnetic-dielectric heterostructure wave-absorbing material is prepared through in-situ heat treatment. In the wave-absorbing material disclosed by the invention, a unique magnetic-dielectric heterogeneous interface is formed by combining an in-situ preparation process under the synergistic effect of double magnetic elements of nickel and iron, so that the wave-absorbing performance is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of wave-absorbing materials, and in particular relates to a wave-absorbing material and a preparation method thereof. Background Art

[0002] With the rapid development of fifth-generation mobile communications (5G), the Internet of Things (IoT), and radar detection systems, electromagnetic waves are increasingly being used in both civilian and military applications. However, the proliferation of electromagnetic devices has also brought significant electromagnetic pollution problems, including potential threats to human health, signal interference with electronic equipment, and the need for stealth in military targets. Traditional electromagnetic shielding methods primarily rely on reflecting electromagnetic waves, but this approach can cause secondary pollution and fails to fundamentally address the problem. Therefore, absorbing materials, which can convert electromagnetic wave energy into heat or other forms of energy dissipation through dielectric loss, magnetic loss, or impedance matching mechanisms, have become key materials for addressing electromagnetic pollution and improving stealth performance. In the military sector in particular, high-performance absorbing materials can effectively reduce the radar cross section (RCS) of weapons and equipment, improving battlefield survivability, and have therefore become a key research focus in various countries.

[0003] At present, traditional absorbing material systems mainly include ferrites, carbon-based materials (such as graphene, carbon nanotubes), conductive polymers and metal powders, and their design is mainly for high-frequency electromagnetic waves (such as X-band and above). However, these materials still face many challenges in practical applications: first, it is difficult to coordinate the optimization of impedance matching and loss mechanism, resulting in insufficient absorption efficiency of materials in specific frequency bands; second, traditional absorbing materials often have problems such as high density, large thickness, and poor environmental stability, which limits their application in lightweight equipment and complex environments; in addition, improving the absorbing performance of low-frequency bands (such as S-band and L-band) is still a technical difficulty, and modern radar and communication systems are gradually expanding to low frequencies, further exacerbating the urgency of material research and development. Although strategies such as multilayer structures, metamaterials and composite modifications have been proposed in recent years to improve absorbing performance, it is still difficult to meet the growing demand for high-efficiency, broadband and lightweight absorbing materials.

[0004] In the face of these challenges, developing a new type of high-efficiency absorbing material that achieves the coordinated optimization of broadband, strong absorption, lightweight, and environmental stability has become a research focus in the field of current electromagnetic functional materials. The material needs to have controllable electromagnetic parameters to optimize impedance matching and enhance the loss mechanism, while also taking into account structural design to expand the effective absorption band. In addition, with the development of intelligent and multifunctional materials, future absorbing materials may also integrate advanced properties such as self-repair and frequency adaptation to meet the application needs of complex electromagnetic environments. Therefore, breaking through the technical bottlenecks of existing absorbing materials and designing and preparing high-performance new absorbing materials are of great significance to solving the problem of electromagnetic pollution. Summary of the Invention

[0005] The present invention aims to address at least one of the aforementioned technical problems existing in the prior art. To this end, the present invention provides a method for preparing an absorbing material. This method involves in-situ preparation of a precursor containing nickel and iron elements, followed by in-situ heat treatment to produce a magnetic-dielectric heterostructure absorbing material. This significantly improves the material's absorbing performance (-90.43 dB).

[0006] A first aspect of the present invention provides a method for preparing an absorbing material, comprising the following steps:

[0007] S1: Dissolve ferrocene in a solvent to form a clear solution, add phenol, and mix well;

[0008] S2: dispersing nickel nanoparticles into the clarified solution of step (1) to obtain a mixed solution;

[0009] S3: transferring the mixed solution to a reaction kettle, adding dimethoxymethane crosslinking agent and boron trifluoride etherate catalyst, and then heating to react;

[0010] S4: removing the solvent from the product of step S3 to obtain a precursor containing nickel and iron elements;

[0011] S5: performing in-situ heat treatment on the precursor containing nickel and iron elements to obtain the absorbing material.

[0012] A technical solution in the method for preparing an absorbing material according to the present invention has at least the following beneficial effects:

[0013] The preparation method of the present invention first prepares a precursor containing nickel and iron elements in situ, and then performs in-situ heat treatment to prepare a magnetic-dielectric heterostructure absorbing material. Among them, the core goal of steps S1 to S4 is to synthesize an organic-inorganic hybrid precursor containing magnetic metals (nickel, iron) and adjustable carbon content, laying the foundation for subsequent heat treatment to form a magnetic-dielectric heterostructure. Step S5 uses high-temperature heat treatment to carbonize and phase-transform the precursor to form a heterostructure with magnetic loss (Fe3C, Ni) and dielectric loss (carbon-based material), thereby optimizing the electromagnetic wave absorption performance. Specifically:

[0014] In step S1, ferrocene (Fe(C2H5)2) provides the iron element, while phenol (C6H5OH) controls the carbon content, which influences the dielectric loss capability of the final material. Ferrocene is dissolved in a solvent to form a homogeneous solution. After the phenol is added, ultrasonic mixing is performed to ensure a stable reaction system.

[0015] In step S2, nickel nanoparticles act as additional magnetic components to enhance magnetic loss capacity and influence phase transition behavior during subsequent heat treatment. Ultrasonic dispersion can be used to uniformly distribute the nickel nanoparticles in the solution to prevent agglomeration.

[0016] In step S3, dimethoxymethane is used as a crosslinking agent to promote the polymerization of phenol and ferrocene to form a stable three-dimensional network structure. Boron trifluoride etherate is used as a Lewis acid catalyst to promote the electrophilic substitution reaction on the aromatic ring and enhance the crosslinking effect.

[0017] In step S4, the solvent in the product of step S3 is removed by volatilization. This evaporation of the solvent yields a solid precursor, which comprises an organic-inorganic hybrid material containing iron and nickel, providing the foundation for subsequent pyrolysis to form a carbon-based composite material. This process can be allowed to stand in a fume hood for 3-7 days to ensure complete solvent evaporation and form a stable precursor.

[0018] In step S5: during the in-situ heat treatment, the organic matter is carbonized at high temperature, the iron and nickel elements form magnetic phases (such as Fe3C and nickel nanoparticles), and the carbon-based matrix provides dielectric loss.

[0019] The microstructure of the final product contains magnetic phase, dielectric phase and heterogeneous interface.

[0020] The magnetic phase consists of Fe3C and nickel nanoparticles. The Fe3C, derived from the thermal decomposition of a cross-linked polymer of phenol and ferrocene monomers, provides magnetic loss. The nickel nanoparticles remain or partially transform into a Ni-C composite phase, enhancing magnetic permeability.

[0021] The dielectric phase consists of a carbon-based matrix and a layered structure. The carbon-based matrix, formed by the carbonization of phenol and ferrocene monomers, regulates the dielectric constant and contributes to dielectric loss. During heat treatment, organic matter decomposes to form a carbon layer, optimizing impedance matching.

[0022] The heterogeneous interfaces are Fe3C / carbon, carbon / carbon and Ni / carbon interfaces. These interfaces form a large number of defects and polarization centers, which enhance the interface polarization loss, improve the absorption performance and broaden the effective absorption band.

[0023] The preparation method of the present invention successfully constructs a magnetic-dielectric heterostructure absorbing material through a two-step method of in-situ polymerization + heat treatment. Its microstructure contains magnetic nanoparticles (Fe3C, Ni) uniformly dispersed in a conductive carbon matrix, forming a multi-scale heterogeneous interface, synergistically optimizing impedance matching and loss mechanism, and is expected to achieve efficient electromagnetic wave absorption.

[0024] The core of this invention is to form a ferrocene / phenol polymer@nickel in situ around the dispersed nickel nanoparticles. After heat treatment, it further forms a magneto-dielectric heterostructure called C@Fe3C / Ni, significantly improving the material's absorption performance (-90.43dB). "C@Fe3C / Ni" refers to the carbon layer surrounding the Fe3C / Ni particles.

[0025] The preparation method of the present invention utilizes sequential precursor preparation and heat treatment steps (i.e., in-situ synthesis → in-situ heat treatment). In-situ synthesis involves dispersing nickel particles in a homogeneous solution, then directly crosslinking the ferrocene and phenol monomers in the homogeneous solution with a crosslinking agent to form a polymer that coats the nickel particles. In-situ heat treatment involves directly heat-treating the product collected from the synthesis without further treatment, thus avoiding uneven dispersion of nickel and iron. Solvent evaporation conditions (e.g., standing for 3-7 days) have a certain influence on the precursor morphology. Combined with post-grinding treatment, the desired target product can be obtained.

[0026] According to some embodiments of the present invention, in step S1, the solvent includes 1,2-dichloroethane.

[0027] According to some embodiments of the present invention, in step S1, if the total molar amount of ferrocene and phenol is 1, the proportion of ferrocene therein is 5% to 75%.

[0028] According to some embodiments of the present invention, in step S1, if the total molar amount of ferrocene and phenol is 1, the proportion of ferrocene therein is any value among 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, and 75%, such as 15%, or a range value formed by any two of them, such as 15% to 30%.

[0029] According to some embodiments of the present invention, in step S1, after adding phenol, ultrasonic treatment may be performed to ensure uniform mixing.

[0030] According to some embodiments of the present invention, in step S2, the amount of nickel nanoparticles added is 0.005 to 0.12 g per 0.01 mol of monomers. The monomers herein refer to the sum of ferrocene and phenol.

[0031] According to some embodiments of the present invention, in step S2, the amount of nickel nanoparticles added is, per 0.01 mol of monomer, any value of 0.005 g, 0.01 g, 0.02 g, 0.03 g, 0.04 g, 0.05 g, 0.06 g, 0.07 g, 0.08 g, 0.09 g, 0.1 g, 0.11 g, and 0.12 g of nickel nanoparticles, such as 0.01 g, or a range value formed by any two of them, such as 0.01 g to 0.06 g.

[0032] According to some embodiments of the present invention, in step S2, the amount of nickel nanoparticles added is 0.005-0.04 g per 0.01 mol of ferrocene and phenol. If the amount is less than 0.005 g, the error is large; if the amount is greater than 0.04 g, the absorption performance is significantly reduced.

[0033] According to some embodiments of the present invention, in step S2, after the nickel nanoparticles are added, ultrasonic treatment can be performed to ensure uniform mixing. The ultrasonic treatment time can be 10 minutes to 30 minutes.

[0034] According to some embodiments of the present invention, in step S3, the molar ratio of the sum of the added amounts of ferrocene and phenol monomers to the dimethoxymethane crosslinking agent is 1:1-5.

[0035] According to some embodiments of the present invention, in step S3, the molar ratio of the sum of the added amounts of ferrocene and phenol monomers to the dimethoxymethane crosslinker is any value of 1:1, 1:2, 1:3, 1:4, or 1:5, such as 1:3, or a range formed by any two of the above, such as 1:3 to 1:4.

[0036] According to some embodiments of the present invention, in step S3, the molar ratio of the catalyst to the monomer may be 1: 1. The monomer herein refers to the sum of ferrocene and phenol.

[0037] According to some embodiments of the present invention, in step S3, after the catalyst is added, magnetic stirring may be performed at a rotation speed of 500-800 rpm for 1-5 minutes.

[0038] According to some embodiments of the present invention, in step S3, the temperature of the temperature-raising reaction is 60°C to 100°C.

[0039] According to some embodiments of the present invention, in step S3, the temperature of the temperature-raising reaction is any one of 60°C, 70°C, 80°C, 90°C, and 100°C, such as 60°C, or a range formed by any two of them, such as 70°C to 80°C.

[0040] According to some embodiments of the present invention, in step S3, the temperature-raising reaction time is 8 hours to 24 hours.

[0041] According to some embodiments of the present invention, in step S3, the time of the temperature rising reaction is any value among 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, 16h, 18h, 20h, and 24h, such as 10h, or a range formed by any two of them, such as 12h to 14h.

[0042] According to some embodiments of the present invention, in step S4, the solvent in the product of step S3 can be removed by volatilization. After cooling, the reactor liner can be removed, the lid can be opened, and the liner can be placed in a fume hood. The liner can be allowed to stand for 3-7 days to evaporate the solvent, thereby obtaining a precursor containing two magnetic elements (nickel and iron).

[0043] According to some embodiments of the present invention, in step S5, the temperature of the in-situ heat treatment is 600°C to 900°C.

[0044] According to some embodiments of the present invention, in step S5, the temperature of the in-situ heat treatment is any one of 600°C, 700°C, 800°C, 900°C, such as 700°C, or a range formed by any two of them, such as 700°C to 800°C.

[0045] According to some embodiments of the present invention, in step S5, the in-situ heat treatment is performed for 1 to 2 hours.

[0046] According to some embodiments of the present invention, in step S5, the heating rate of the in-situ heat treatment may be 5°C / min.

[0047] After in situ heat treatment, the sample can be ground.

[0048] The second aspect of the present invention provides an absorbing material prepared by the preparation method of the first aspect of the present invention.

[0049] The absorbing material of the present invention, the synergistic effect of the dual magnetic elements of nickel and iron, combined with in-situ preparation, forms a unique magnetic-dielectric heterogeneous interface (the uniqueness here refers to the formation of a magnetic-dielectric heterogeneous structure from the outside to the inside), thereby improving the absorbing performance.

[0050] The balance between the dielectric loss and magnetic loss of the material can be controlled by combining parameters (such as nickel content and heat treatment temperature). Specifically, the temperature of heat treatment will affect the phase composition of the material and the degree of graphitization of carbon. When the temperature is low, it is difficult to form magnetic Fe3C, and the degree of graphitization of carbon is low, the dielectric loss and magnetic loss are small, which is not conducive to the absorption performance. Too high a temperature may cause the degree of graphitization of carbon to be too high, which will cause an abnormality in the dielectric constant, and ultimately lead to impedance mismatch and reduced absorption performance. Nickel is a magnetic metal particle. Too high or too low a nickel content will affect the magnetic loss of the material, and the impedance matching cannot be optimized, resulting in reduced absorption performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 1 is the infrared spectrum of the target precursors of Examples 1 to 3.

[0052] Figure 2 1 and 2 are X-ray diffraction spectra of the absorbing materials of Examples 1 to 3.

[0053] Figure 3 This is the test result of the absorbing performance of the absorbing material of Example 1.

[0054] Figure 4 This is the test result of the absorbing performance of the absorbing material of Example 2.

[0055] Figure 5 This is the test result of the absorbing performance of the absorbing material of Example 3. DETAILED DESCRIPTION

[0056] The following are specific embodiments of the present invention, and the technical solutions of the present invention are further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0057] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with the embodiments to fully understand the purpose, features and effects of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0058] In the description of the present invention, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the exemplary expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0059] Unless otherwise specified, "room temperature" in the present invention means 25°C±5°C.

[0060] Unless otherwise specified, “about” in the present invention means that the allowable error is within ±2%.

[0061] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or those recommended by the manufacturer. All reagents or instruments used, if the manufacturer is not specified, are commercially available conventional products.

[0062] Example 1

[0063] A wave absorbing material is prepared, and the specific steps are as follows:

[0064] (1) Ferrocene and phenol are used as monomers, with a total molar number of 0.01 mol. 0.0015 mol of ferrocene is weighed and dissolved in approximately 30 mL of 1,2-dichloroethane to form a clear solution. 0.0085 mol of phenol is added to the clear solution and ultrasonically mixed.

[0065] (2) nickel nanoparticles (0.005 g) were dispersed into the clear solution and ultrasonically dispersed for 15 min to obtain nickel nanoparticles;

[0066] (3) Transfer the mixed solution to the liner of a 50 mL reactor;

[0067] (4) Add 0.03 mol of dimethoxymethane crosslinker while stirring, stir evenly with magnetic stirring at a speed of 600 rpm for 3 minutes;

[0068] (5) Add 0.01 mol of boron trifluoride etherate catalyst, stir evenly with magnetic stirring at a speed of 600 rpm for 1 minute, remove the stirring bar, cover with the inner liner lid, and place in the reactor;

[0069] (6) Move the reactor to a forced air oven, raise the temperature to 80°C, and react for 12 hours;

[0070] (7) After cooling, the reactor liner was removed and the lid was opened. The liner was placed in a fume hood and allowed to stand for 7 days to evaporate the solvent. The target precursor containing two magnetic elements (nickel and iron) was obtained.

[0071] (8) The target precursor was subjected to in-situ heat treatment in a tube furnace. The heat treatment atmosphere was argon atmosphere, the heat treatment temperature was set to 800 °C, the heat treatment time was 2 h, and the heating rate was 5 °C / min;

[0072] (9) The heat-treated sample is ground to obtain the target product with a magnetic-dielectric heterostructure.

[0073] The infrared spectrum of the target precursor is shown in Figure 1 As shown, it can be seen that the molecular structures of the obtained products are similar and the addition of nickel has little effect on them.

[0074] The X-ray diffraction spectrum of the product obtained after heat treatment is as follows Figure 2 The components of the product are mainly C, Fe3C and Ni, and the absorbing properties are as follows Figure 3 As shown, it is shown that the preparation method of this embodiment can obtain an absorbing material with good absorbing performance, a minimum reflection loss of -69.05 dB, a thickness of 2.09 mm, and an effective absorption bandwidth of 5.51 GHz.

[0075] It can be seen that the preparation process described in this embodiment is simple, the preparation temperature is low, and the obtained product has good wave absorbing performance.

[0076] Example 2

[0077] A wave absorbing material is prepared, and the specific steps are as follows:

[0078] (1) Ferrocene and phenol are used as monomers, with a total molar number of 0.01 mol. 0.0015 mol of ferrocene is weighed and dissolved in approximately 30 mL of 1,2-dichloroethane to form a clear solution. 0.0085 mol of phenol is added to the clear solution and ultrasonically mixed.

[0079] (2) nickel nanoparticles (0.02 g) were dispersed into the clear solution and ultrasonically dispersed for 15 min to obtain nickel nanoparticles;

[0080] (3) Transfer the mixed solution to the liner of a 50 mL reactor;

[0081] (4) Add 0.03 mol of dimethoxymethane crosslinker while stirring, stir evenly with magnetic stirring at a speed of 600 rpm for 3 minutes;

[0082] (5) Add 0.01 mol of boron trifluoride etherate catalyst, stir evenly with magnetic stirring at a speed of 600 rpm for 1 minute, remove the stirring bar, cover with the inner liner lid, and place in the reactor;

[0083] (6) Move the reactor to a forced air oven, raise the temperature to 80°C, and react for 12 hours;

[0084] (7) After cooling, the reactor liner was removed and the lid was opened. The liner was placed in a fume hood and allowed to stand for 7 days to evaporate the solvent. The target precursor containing two magnetic elements (nickel and iron) was obtained.

[0085] (8) The target precursor was subjected to in-situ heat treatment in a tube furnace. The heat treatment atmosphere was argon atmosphere, the heat treatment temperature was set to 800 °C, the heat treatment time was 2 h, and the heating rate was 5 °C / min;

[0086] (9) The heat-treated sample is ground to obtain the target product with a magnetic-dielectric heterostructure.

[0087] The infrared spectrum of the target precursor is shown in Figure 1 As shown in Figure 2, it can be seen that the molecular structures of the obtained products are similar and the addition of nickel has little effect on them. The X-ray diffraction spectrum of the product obtained after heat treatment is shown in Figure 2. Figure 2 The components of the product are mainly C, Fe3C and Ni, and the absorbing properties are as follows Figure 4 As shown, it is shown that the preparation method of this embodiment can obtain an absorbing material with good absorbing performance, a minimum reflection loss of -90.43 dB, a thickness of 2.94 mm, and an effective absorption bandwidth of 4.06 GHz.

[0088] It can be seen that the preparation process described in this embodiment is simple, the preparation temperature is low, and the obtained product has more excellent wave absorbing performance.

[0089] Example 3

[0090] A wave absorbing material is prepared, and the specific steps are as follows:

[0091] (1) Ferrocene and phenol are used as monomers, with a total molar amount of 0.01 mol. 0.0015 mol of ferrocene is dissolved in approximately 30 mL of 1,2-dichloroethane to form a clear solution. 0.0085 mol of phenol is added to the clear solution and ultrasonically mixed.

[0092] (2) Nickel nanoparticles (0.04 g) prepared in the laboratory were dispersed into the clear solution and ultrasonically dispersed for 15 minutes to obtain nickel nanoparticles;

[0093] (3) Transfer the mixed solution to the liner of a 50 mL reactor;

[0094] (4) Add 0.03 mol of dimethoxymethane crosslinker while stirring, stir evenly with magnetic stirring at a speed of 600 rpm for 3 minutes;

[0095] (5) Add 0.01 mol of boron trifluoride etherate catalyst, stir evenly with magnetic stirring at a speed of 600 rpm for 1 minute, remove the stirring bar, cover with the inner liner lid, and place in the reactor;

[0096] (6) Move the reactor to a forced air oven, raise the temperature to 80°C, and react for 12 hours;

[0097] (7) After cooling, the reactor liner was removed and the lid was opened. The liner was placed in a fume hood and allowed to stand for 7 days to evaporate the solvent. The target precursor containing two magnetic elements (nickel and iron) was obtained.

[0098] (8) The target precursor was subjected to in-situ heat treatment in a tube furnace. The heat treatment atmosphere was argon atmosphere, the heat treatment temperature was set to 800 °C, the heat treatment time was 2 h, and the heating rate was 5 °C / min;

[0099] (9) The heat-treated sample is ground to obtain the target product with a magnetic-dielectric heterostructure.

[0100] The infrared spectrum of the target precursor is shown in Figure 1 As shown in Figure 2, it can be seen that the molecular structures of the obtained products are similar and the addition of nickel has little effect on them. The X-ray diffraction spectrum of the product obtained after heat treatment is shown in Figure 2. Figure 2 The components of the product are mainly C, Fe3C and Ni. Figure 5 As shown, it is shown that the preparation method of this embodiment can obtain an absorbing material with good absorbing performance, a minimum reflection loss of -20.88dB, a thickness of 5.00mm, and an effective absorption bandwidth of 2.07GHz.

[0101] It can be seen that the preparation process described in this embodiment is simple, and the increase in nickel content leads to impedance mismatch and skin effect, while also causing a decrease in high-frequency magnetic loss capacity, resulting in poor microwave absorption performance of the final product.

[0102] The present invention has been described in detail above with reference to the embodiments. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the relevant technical field without departing from the spirit of the present invention.

Claims

1. A method for preparing a wave absorbing material, characterized in that: The following steps are involved: S1: Dissolve ferrocene in a solvent to form a clear solution, add phenol, and mix well; S2: dispersing nickel nanoparticles into the clarified solution of step (1) to obtain a mixed solution; S3: transferring the mixed solution to a reaction kettle, adding dimethoxymethane crosslinking agent and boron trifluoride etherate catalyst, and then heating to react; S4: removing the solvent from the product of step S3 to obtain a precursor containing nickel and iron elements; S5: performing in-situ heat treatment on the precursor containing nickel and iron elements to obtain the absorbing material.

2. The preparation method according to claim 1, characterized in that In step S1, the solvent includes 1,2-dichloroethane.

3. The preparation method according to claim 1, characterized in that In step S1, if the total molar amount of ferrocene and phenol is 1, the proportion of ferrocene therein is 5% to 75%.

4. The preparation method according to claim 1, characterized in that In step S2, 0.005 to 0.12 g of nickel nanoparticles are added for every 0.01 mol of monomer.

5. The preparation method according to claim 1, characterized in that In step S3, the molar ratio of the sum of the added amounts of ferrocene and phenol monomers to the dimethoxymethane cross-linking agent is 1:1-5.

6. The preparation method according to claim 1, characterized in that In step S3, the temperature of the temperature-raising reaction is 60°C to 100°C.

7. The preparation method according to claim 6, characterized in that In step S3, the temperature-raising reaction time is 8 hours to 24 hours.

8. The preparation method according to claim 1, characterized in that In step S5, the temperature of the in-situ heat treatment is 600°C to 900°C.

9. The preparation method according to claim 8, characterized in that In step S5, the in-situ heat treatment time is 1 hour to 2 hours.

10. A wave absorbing material, characterized in that: Prepared by the preparation method according to any one of claims 1 to 9.

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