Metal-coated silicon carbide nanowire wave-absorbing material as well as preparation method and application thereof

Abstract

The invention discloses a metal-coated silicon carbide nanowire wave-absorbing material as well as a preparation method and application thereof, and particularly relates to the field of wave-absorbing composite materials. Comprising a three-dimensional network structure formed by mutually lapping a plurality of silicon carbide nanowires, and the surface of each silicon carbide nanowire is coated with a metal layer; a heterogeneous interface is formed between the silicon carbide nanowire and the metal, and interface polarization is generated on the heterogeneous interface; the effective absorption bandwidth of the wave-absorbing material is 6.48 GHz, and the minimum reflection loss is-41dB; the wave-absorbing material is obtained by performing metal deposition on the surface of the silicon carbide nanowire. The silicon carbide nanowire and the metal layer form a core-shell structure, a heterogeneous interface is formed between the silicon carbide nanowire and the metal layer, interface polarization is generated on the heterogeneous interface, the polarization relaxation process can strongly dissipate electromagnetic wave energy, and therefore the electromagnetic wave absorption performance is improved.

Description

Technical Field

[0001] This application relates to the field of microwave absorbing composite materials, and in particular to a metal-coated silicon carbide nanowire microwave absorbing material, its preparation method, and its application. Background Technology

[0002] With the rapid development of next-generation mobile communication technology and Internet of Things (IoT) technology, the increasingly serious problems of electromagnetic interference and electromagnetic radiation urgently need to be addressed. Traditional absorbing materials are limited in their application in high-temperature and lightweight scenarios due to their high density, narrow absorption bandwidth, and limited thermal stability. Therefore, developing novel absorbing materials that combine strong absorption, wide bandwidth, and low density has become a current research focus.

[0003] Silicon carbide nanowires, as a wide-bandgap semiconductor, possess advantages such as high strength, high melting point, and good chemical stability. They also combine the high aspect ratio, high specific surface area, and outstanding mechanical properties of one-dimensional materials. The nanowires interlock to form a three-dimensional network structure, making them a promising next-generation lightweight electromagnetic wave absorbing material. However, pure-phase silicon carbide nanowires have relatively low electrical conductivity and weak conductivity loss. Their relatively high real part and low imaginary part of dielectric constant lead to poor impedance matching and dielectric properties, resulting in poor wave absorption performance. Summary of the Invention

[0004] The main objective of this application is to provide a metal-coated silicon carbide nanowire microwave absorbing material, its preparation method, and its application, aiming to solve the problem of poor microwave absorption performance of existing pure-phase silicon carbide nanowires.

[0005] To achieve the above objectives, this application provides a metal-coated silicon carbide nanowire microwave absorbing material, comprising a three-dimensional network structure formed by multiple silicon carbide nanowires overlapping each other, and each silicon carbide nanowire surface coated with a metal layer; a heterogeneous interface is formed between the silicon carbide nanowires and the metal, and interfacial polarization is generated at the heterogeneous interface; the effective absorption bandwidth of the microwave absorbing material is 6.48 GHz, and the minimum reflection loss is -41 dB; the microwave absorbing material is obtained by metal deposition on the surface of silicon carbide nanowires; wherein, the deposition process includes: acid treatment of silicon carbide nanowires to obtain a first intermediate product; silanization of the first intermediate product to obtain a second intermediate product; free radical polymerization of the second intermediate product to obtain a third intermediate product, the third intermediate product being silicon carbide nanowires with a polymer layer on the surface; catalytic treatment of the third intermediate product to obtain a fourth intermediate product; and chemical plating of the fourth intermediate product with a metal plating solution to obtain the microwave absorbing material, the metal plating solution comprising a reducing agent and metal ions.

[0006] Optionally, during the acid treatment, a mixture of sulfuric acid solution and nitric acid solution is used to treat the silicon carbide nanowires; during the silanization process, a mixture of trimethoxysilane solution, ethanol, acetic acid and deionized water is used to treat the first intermediate product.

[0007] Optionally, during the free radical polymerization process, the second intermediate product is treated with a mixture of methacryloyloxyethyltrimethylammonium chloride and potassium persulfate aqueous solution; the catalyst is ammonium chloropalladate solution.

[0008] Optionally, the diameter of the silicon carbide nanowires is 100-600 nm and the length is 50-100 μm.

[0009] Optional metals include copper, nickel, gold, or silver.

[0010] To achieve the above objectives, this application also provides a method for preparing a metal-coated silicon carbide nanowire microwave absorbing material, comprising: dispersing silicon carbide nanowires in a solvent and filtering them to obtain a silicon carbide nanowire filter cake; placing the silicon carbide nanowire filter cake in a mixed solution of sulfuric acid and nitric acid and reacting it at a temperature of 75-85℃ for 1.5-2.5 h to obtain a first intermediate product; immersing the first intermediate product in a mixed solution of trimethoxysilane, ethanol, acetic acid and deionized water to obtain a second intermediate product; immersing the second intermediate product in a mixed solution of methacryloyloxyethyltrimethylammonium chloride and potassium persulfate aqueous solution and reacting it at a temperature of 75-85℃ for 0.5-1.5 h to obtain a third intermediate product; immersing the third intermediate product in an ammonium chloropalladate solution to obtain a fourth intermediate product; and immersing the fourth intermediate product in a metal plating bath to obtain a microwave absorbing material, wherein the metal plating bath includes a reducing agent and metal ions.

[0011] Optionally, the volume ratio of sulfuric acid to nitric acid is (4-2):1.

[0012] Optionally, the volume ratio of trimethoxysilane solution, ethanol, acetic acid and deionized water is 1:(15-40):(0.1-1):(0.5-2).

[0013] Optionally, the volume ratio of methacryloyloxyethyltrimethylammonium chloride to potassium persulfate aqueous solution is 1:(1.6-5).

[0014] To achieve the above objectives, this application also provides an application of metal-coated silicon carbide nanowire absorbing material in electromagnetic absorption.

[0015] Compared with the prior art, the beneficial effects of this application are as follows: The metal-coated silicon carbide nanowire absorbing material of this invention forms a core-shell structure with a metal layer, creating a heterogeneous interface between the silicon carbide nanowires and the metal. This interface polarization, through a polarization relaxation process, strongly dissipates electromagnetic wave energy, thereby improving electromagnetic wave absorption performance. The core-shell structure provides a large specific surface area, increasing the number of interfaces and significantly enhancing electromagnetic wave energy dissipation and absorption performance. Coating the silicon carbide nanowires with metal further emphasizes the role of the three-dimensional network structure. The random three-dimensional network allows the nanowires to overlap, forming conductive pathways throughout the material. Under the influence of an alternating electromagnetic field, the metal conductor generates a strong conduction current. When this current flows through a metal layer with a certain resistance, it generates Joule heating, resulting in energy loss (conduction loss). Simultaneously, the alternating electromagnetic field induces eddy currents in the metal, which dissipate energy through Joule heating (eddy current loss). This multi-faceted, synergistic energy dissipation mechanism, achieved through conduction loss and eddy current loss, further enhances the electromagnetic wave absorption performance of the absorbing material. Attached Figure Description

[0016] Figure 1 An optical image of the metal-coated silicon carbide nanowire absorbing material prepared in Example 1 of this application; Figure 2 SEM images of silicon carbide nanowires and the metal-coated silicon carbide nanowire absorbing material prepared in Example 1; Figure 3 XRD patterns of silicon carbide nanowires and the metal-coated silicon carbide nanowire microwave absorbing material prepared in Example 1; Figure 4 The dielectric constant and tangent loss angle variation curves of silicon carbide nanowires and the metal-coated silicon carbide nanowire microwave absorbing material prepared in Example 1; Figure 5 Microwave absorption performance diagrams of silicon carbide nanowires and the metal-coated silicon carbide nanowire absorbing material prepared in Example 1.

[0017] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] The first embodiment of the present invention provides a metal-coated silicon carbide nanowire microwave absorbing material, characterized in that it comprises a three-dimensional network structure formed by multiple silicon carbide nanowires overlapping each other, and each silicon carbide nanowire is coated with a metal layer; a heterogeneous interface is formed between the silicon carbide nanowires and the metal, and interfacial polarization is generated at the heterogeneous interface; the effective absorption bandwidth of the microwave absorbing material is 6.48 GHz, and the minimum reflection loss is -41 dB; the microwave absorbing material is obtained by metal deposition on the surface of silicon carbide nanowires; wherein the deposition process includes: acid treatment of silicon carbide nanowires to obtain a first intermediate product; silanization of the first intermediate product to obtain a second intermediate product; free radical polymerization of the second intermediate product to obtain a third intermediate product, the third intermediate product being silicon carbide nanowires with a polymer layer on the surface; catalysis of the third intermediate product with a catalyst to obtain a fourth intermediate product; and chemical plating of the fourth intermediate product with a metal plating solution containing metal ions to obtain the microwave absorbing material.

[0020] It is worth noting that the three-dimensional network structure is formed by randomly overlapping multiple silicon carbide nanowires and does not require special treatment.

[0021] In this embodiment, the absorbing material is a core-shell structure composed of a metal shell and a single silicon carbide nanowire core. Numerous heterogeneous interfaces are formed between SiC and the metal, exhibiting significant differences in dielectric constant. Under the influence of an electromagnetic field, charge accumulates at these interfaces, resulting in interfacial polarization. This polarization relaxation process strongly dissipates electromagnetic wave energy. Defects, functional groups on the nanowire surface, and the metal nanoparticles themselves can all serve as polarization centers, undergoing reorientation and relaxation under the influence of an electromagnetic field, thus consuming energy. Furthermore, the core-shell structure provides a large specific surface area, increasing the number of interfaces and significantly enhancing the dissipation of electromagnetic wave energy, thereby improving electromagnetic wave absorption performance. Multiple silicon carbide nanowires randomly overlap to form a three-dimensional network structure. Coating each silicon carbide nanowire with metal further accentuates the three-dimensional network structure while retaining the characteristics of one-dimensional silicon carbide nanowires. The three-dimensional network forms a conductive path throughout the material, which is beneficial for conduction loss. Furthermore, under the action of an alternating electromagnetic field, a strong conduction current is generated in a metallic conductor. When this conduction current flows through a metal layer with a certain resistance, it generates Joule heat and loses energy, i.e., conduction loss. At the same time, the alternating electromagnetic field induces eddy currents in the metal, which dissipate energy through Joule heat, i.e., eddy current loss. Through conduction loss and eddy current loss, a multi-faceted and synergistic energy dissipation mechanism is constructed. Meanwhile, the impedance matching characteristics are cleverly optimized, thereby improving the electromagnetic wave absorption performance of the absorbing material.

[0022] Furthermore, during the acid treatment, a mixture of sulfuric acid and nitric acid solutions is used to treat the silicon carbide nanowires. During silanization, a mixture of trimethoxysilane solution, ethanol, acetic acid, and deionized water is used to treat the first intermediate product. During free radical polymerization, a mixture of methacryloyloxyethyltrimethylammonium chloride and potassium persulfate aqueous solution is used to treat the second intermediate product. The catalyst is ammonium chloropalladate solution. The silicon carbide nanowires have a diameter of 100-600 nm and a length of 50-100 μm. The metals used include copper, nickel, gold, or silver.

[0023] The second embodiment of the present invention provides a method for preparing a metal-coated silicon carbide nanowire microwave absorbing material, specifically including the following steps: Step S1: Disperse silicon carbide nanowires in a solvent and filter them to obtain silicon carbide nanowire filter cake. Specifically, silicon carbide nanowires are dispersed in ethanol to obtain a silicon carbide nanowire dispersion, and the silicon carbide nanowire dispersion is filtered to obtain a silicon carbide nanowire filter cake.

[0024] Step S2: Place the silicon carbide nanowire filter cake in a mixed solution of sulfuric acid and nitric acid, and react at a temperature of 75-85℃ for 1.5-2.5h to obtain the first intermediate product; wherein the volume ratio of sulfuric acid to nitric acid is (4-2):1; for example, when the silicon carbide nanowire is 0.1g, the volume of sulfuric acid is 20-40 mL and the volume of nitric acid is 5-15 mL. Acid treatment of silicon carbide nanowires is to remove surface impurities and to hydroxylate the surface of the silicon carbide nanowires, thereby forming hydroxyl groups on the surface of the silicon carbide nanowires.

[0025] Step S3: Immerse the first intermediate product in a mixed solution of trimethoxysilane, ethanol, acetic acid, and deionized water, and react at 25°C for 1 hour to obtain the second intermediate product; wherein the volume ratio of trimethoxysilane, ethanol, acetic acid, and deionized water is 1:(15-40):(0.1-1):(0.5-2); for example, when the silicon carbide nanowire is 0.1 g, the volume of trimethoxysilane solution is 5-10 mL, the volume of ethanol is 150-200 mL, the volume of acetic acid is 1-5 mL, and the volume of deionized water is 5-10 mL. During this process, the hydroxyl groups on the surface of silicon carbide nanowires undergo dehydration condensation with the silanol groups in the trimethoxysilane solution to form Si-O-Si covalent bonds. These covalent bonds serve as polymerizable functional groups, enabling the chemical grafting of silane molecules onto the silicon carbide surface and enhancing interfacial adhesion.

[0026] Step S4: The second intermediate product is immersed in a mixture of methacryloyloxyethyltrimethylammonium chloride (METAC) and potassium persulfate aqueous solution, and reacted at a temperature of 75-85℃ for 0.5-1.5 h to obtain the third intermediate product; wherein the volume ratio of methacryloyloxyethyltrimethylammonium chloride to potassium persulfate aqueous solution is 1:(1.6-5); for example, when the silicon carbide nanowire is 0.1 g, the volume of methacryloyloxyethyltrimethylammonium chloride is 40-60 mL, and the volume of potassium persulfate aqueous solution is 100-200 mL; In this process, the free radicals generated by the decomposition of potassium persulfate initiate the free radical grafting polymerization of METAC monomers on the surface of silicon carbide nanowires, thereby producing a METAC polymer layer. This facilitates the subsequent fixation of the catalyst, achieves uniform metal deposition, provides a three-dimensional network structure, and enhances the adhesion of the coating.

[0027] Step S5: Immerse the third intermediate in ammonium chloropalladate solution for 20 min in the dark to obtain the fourth intermediate; In this process, silicon carbide nanowires with METAC polymer layers react with ammonium chloropalladate to load palladium ions onto the METAC polymer layers, forming highly catalytically active surface sites that provide uniformly distributed nucleation sites for metal deposition.

[0028] Step S6: Immerse the fourth intermediate product in a metal plating bath and react at 25°C for 30 minutes to obtain a microwave absorbing material; the metal plating bath includes a reducing agent and metal ions. In this process, the reducing agent undergoes an oxidation reaction at the Pd active sites, generating electrons. These electrons are then used to reduce metal ions in the solution, causing them to precipitate around the palladium sites and form an initial layer of metal atoms, thereby depositing metal ions on the surface of silicon carbide nanowires.

[0029] The third embodiment of the present invention provides an application of a metal-coated silicon carbide nanowire absorbing material in electromagnetic absorption.

[0030] Specifically, paraffin wax and n-hexane are mixed evenly to obtain a paraffin wax solution, and the above-mentioned microwave absorbing material is added to it. The solution is then ground in a mortar to make it evenly mixed. After solidification, it is placed in a mold to obtain the electromagnetic microwave absorbing material.

[0031] Example 1 Step S10: Disperse 0.1g of silicon carbide nanowires in 20mL of ethanol, and after magnetic stirring for 20min, the dispersion is uniform to obtain silicon carbide nanowire dispersion. Filter the dispersion to obtain silicon carbide nanowire filter cake. Step S20: The silicon carbide nanowire filter cake is placed in a mixed solution of 30 mL sulfuric acid and 10 mL nitric acid, reacted at 80 °C for 2 h, and the product is washed with deionized water several times, collected by filtration, and the first intermediate product is obtained. Step S30: The first intermediate product is immersed in a mixed solution of 8 mL trimethoxysilane solution, 190 mL ethanol, 8 mL deionized water and 2 mL acetic acid, reacted at 25 °C for 1 h, and washed repeatedly with deionized water to obtain the second intermediate product. Step S40: Mix 0.4g of potassium persulfate and 150mL of deionized water to obtain an aqueous solution of potassium persulfate. Immerse the second intermediate product in a mixture of 50mL of methacryloyloxyethyltrimethylammonium chloride and the above aqueous solution of potassium persulfate, and react at 80°C for 1h to obtain the third intermediate product. Step S50: Immerse the third intermediate in 200 mL of ammonium chloropalladate solution for 20 min in the dark to obtain the fourth intermediate. In step S60, 12 g / L NaOH, 13 g / L CuSO4•5H2O and 29 g / L KNaC4H4O6•4H2O are mixed to obtain solution A. 9.5 mol / L formaldehyde aqueous solution (reducing agent) is used as solution B. 100 mL of solution A and 100 mL of solution B are mixed to obtain a metal plating solution. The fourth intermediate product is immersed in the above metal plating solution and reacted at 25 °C for 30 min to obtain copper-coated silicon carbide nanowire microwave absorbing material SiCnw@Cu.

[0032] The microstructure and performance of silicon carbide nanowires and the copper-coated silicon carbide nanowire microwave absorbing material obtained in Example 1 were characterized, and the results are as follows.

[0033] Optical images of the copper-coated silicon carbide nanowires obtained in Example 1 are shown below. Figure 1 As can be observed, the silicon carbide nanowires are reddish-brown in appearance. SEM images of the silicon carbide nanowires and the copper-coated silicon carbide nanowires obtained in Example 1 are shown below. Figure 2 .from Figure 2 In (a) and (b), it can be seen that the uncoated silicon carbide nanowires overlap to form a network and have a smooth surface; from Figure 2 As can be seen in (c) and (d), the surface of silicon carbide nanowires is tightly coated with metallic copper and the surface becomes rough. Even after being coated with copper, the silicon carbide nanowires still maintain their original three-dimensional network structure.

[0034] XRD patterns of silicon carbide nanowires and copper-coated silicon carbide nanowires obtained in Example 1 are shown below. Figure 3As can be seen from the figure, the peak values ​​of SiCnw (silicon carbide nanowires) at 41.565°, 48.33°, 70.925°, and 85.665° correspond to the (111), (200), (220), and (311) crystal planes of SiC, respectively. The peak values ​​of SiCnw@Cu (copper-coated silicon carbide nanowires) at 50.942°, 59.234°, and 88.667° correspond to the characteristic peaks of CuPDF#00-001-1241, respectively, proving the successful preparation of the SiCnw@Cu composite material.

[0035] The dielectric constants and tangent loss angles of silicon carbide nanowires and copper-coated silicon carbide nanowires are shown in [reference needed]. Figure 4 , Figure 4 In the figure (a), the real part of the dielectric constant of SiCnw and SiCnw@Cu is given. Figure 4 In the figure (b), the imaginary part of the dielectric constant of SiCnw and SiCnw@Cu is given. Figure 4 In the figure (c), the tangent loss angles of SiCnw and SiCnw@Cu are shown. It can be seen that after coating with copper, the real part of the dielectric constant of the composite material decreases, but the imaginary part increases, and the curve changes relatively gently. The tangent loss angle of SiCnw@Cu is significantly higher than that of pure SiCnw, which indicates that coating with copper enhances the electromagnetic wave loss capability of the material.

[0036] The microwave absorption properties of silicon carbide nanowires and copper-coated silicon carbide nanowires are shown in [reference needed]. Figure 5 , Figure 5 (a) shows the microwave absorption performance of SiCnw. Figure 5 Figure (b) shows the absorption performance of SiCnw@Cu. It can be seen that the prepared SiCnw@Cu has excellent electromagnetic wave absorption performance, with an effective absorption bandwidth of 6.48 GHz and a minimum reflection loss of -41 dB when the thickness is 2.1 mm.

[0037] Example 2 Step S10: Disperse 0.1g of silicon carbide nanowires in 20mL of ethanol, and after magnetic stirring for 20min, the dispersion is uniform to obtain silicon carbide nanowire dispersion. Filter the dispersion to obtain silicon carbide nanowire filter cake. Step S20: The silicon carbide nanowire filter cake is placed in a mixed solution of 20 mL sulfuric acid and 5 mL nitric acid, reacted at 75 °C for 2 h, and the product is washed with deionized water several times, collected by suction filtration, and the first intermediate product is obtained. Step S30: The first intermediate product is immersed in a mixed solution of 5 mL trimethoxysilane solution, 150 mL ethanol, 8 mL deionized water and 1 mL acetic acid, reacted at 25 °C for 1 h, and rinsed several times with deionized water to obtain the second intermediate product. Step S40: Mix 0.4g of potassium persulfate and 100mL of deionized water to obtain an aqueous solution of potassium persulfate. Immerse the second intermediate product in a mixture of 40mL of methacryloyloxyethyltrimethylammonium chloride and the above aqueous solution of potassium persulfate, and react at 75°C for 1h to obtain the third intermediate product. Step S50: Immerse the third intermediate in 200 mL of ammonium chloropalladate solution for 20 min in the dark to obtain the fourth intermediate; In step S60, 12 g / L NaOH, 13 g / L AgNO3 and 29 g / L KNaC4H4O6•4H2O are mixed to obtain solution A. 9.5 mol / L formaldehyde aqueous solution (reducing agent) is used as solution B. 100 mL of solution A and 100 mL of solution B are mixed to obtain a metal plating solution. The fourth intermediate product is immersed in the above metal plating solution and reacted at 25 °C for 30 min to obtain silver-coated silicon carbide nanowire microwave absorbing material SiCnw@Ag.

[0038] Example 3 Step S10: Disperse 0.1g of silicon carbide nanowires in 20mL of ethanol, and after magnetic stirring for 20min, the dispersion is uniform to obtain silicon carbide nanowire dispersion. Filter the dispersion to obtain silicon carbide nanowire filter cake. Step S20: The silicon carbide nanowire filter cake is placed in a mixed solution of 40 mL sulfuric acid and 15 mL nitric acid, reacted at 85 °C for 2 h, and the product is washed with deionized water several times, collected by filtration, and the first intermediate product is obtained. Step S30: The first intermediate product is immersed in a mixed solution of 10 mL trimethoxysilane solution, 200 mL ethanol, 10 mL deionized water and 5 mL acetic acid, reacted at 25 °C for 1 h, and washed repeatedly with deionized water to obtain the second intermediate product. Step S40: Mix 0.4g of potassium persulfate and 200mL of deionized water to obtain an aqueous solution of potassium persulfate. Immerse the second intermediate product in a mixture of 60mL of methacryloyloxyethyltrimethylammonium chloride and the above aqueous solution of potassium persulfate, and react at 85°C for 1h to obtain the third intermediate product. Step S50: Immerse the third intermediate in 200 mL of ammonium chloropalladate solution for 20 min in the dark to obtain the fourth intermediate; In step S60, 80 g / L Ni2SO4•5H2O, 40 g / L sodium citrate and 20 g / L lactic acid are mixed to obtain solution A. 1.5 g / L dimethylamine borane aqueous solution (reducing agent) is used as solution B. 100 mL of solution A and 100 mL of solution B are mixed to obtain a metal plating solution. The fourth intermediate product is immersed in the above metal plating solution and reacted at 25 °C for 30 min to obtain nickel-coated silicon carbide nanowire microwave absorbing material SiCnw@Ni.

[0039] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A metal-coated silicon carbide nanowire wave-absorbing material, characterized in that, The three-dimensional network structure is formed by a plurality of silicon carbide nanowires which are mutually overlapped, and each silicon carbide nanowire is coated with a metal layer; a heterojunction interface is formed between the silicon carbide nanowire and the metal, and interface polarization is generated at the heterojunction interface; The effective absorption bandwidth of the wave-absorbing material is 6.48 GHz, and the minimum reflection loss is -41 dB. The wave-absorbing material is obtained by metal deposition on the surface of the silicon carbide nanowire. The deposition process comprises: The silicon carbide nanowire is subjected to acid treatment to obtain a first intermediate product; The first intermediate product is subjected to silanization to obtain a second intermediate product; The second intermediate product is subjected to radical polymerization to obtain a third intermediate product, which is a silicon carbide nanowire with a polymer layer on the surface; The third intermediate product is subjected to catalytic treatment to obtain a fourth intermediate product; The fourth intermediate product is subjected to chemical plating treatment by a metal plating solution to obtain the wave-absorbing material, and the metal plating solution comprises a reducing agent and metal ions.

2. The metal-coated silicon carbide nanowire wave-absorbing material of claim 1, wherein, During the acid treatment, the silicon carbide nanowire is treated with a mixed solution of sulfuric acid and nitric acid; During the silanization, the first intermediate product is treated with a mixed solution of trimethoxysilane solution, ethanol, acetic acid and deionized water.

3. The metal-coated silicon carbide nanowire wave-absorbing material of claim 1, wherein, During the radical polymerization, the second intermediate product is treated with a mixed solution of methacryloyloxyethyl trimethyl ammonium chloride and potassium persulfate aqueous solution; The catalyst is ammonium chloropalladic acid solution.

4. The metal-coated silicon carbide nanowire wave-absorbing material of claim 1, wherein, The diameter of the silicon carbide nanowire is 100-600 nm, and the length is 50-100 μm.

5. The metal-coated silicon carbide nanowire wave-absorbing material of claim 1, wherein, The metal comprises copper, nickel, gold or silver.

6. A method of preparing the metal-coated silicon carbide nanowire wave-absorbing material according to claim 1, characterized in that, The method comprises: The silicon carbide nanowire is dispersed in a solvent and subjected to suction filtration to obtain a silicon carbide nanowire filter cake; The silicon carbide nanowire filter cake is placed in a mixed solution of sulfuric acid and nitric acid, and reacted at a temperature of 75-85 °C for 1.5-2.5 h to obtain a first intermediate product; The first intermediate product is immersed in a mixed solution of trimethoxysilane solution, ethanol, acetic acid and deionized water to obtain a second intermediate product; The second intermediate product is immersed in a mixed solution of methacryloyloxyethyl trimethyl ammonium chloride and potassium persulfate aqueous solution, and reacted at a temperature of 75-85 °C for 0.5-1.5 h to obtain a third intermediate product; The third intermediate product is immersed in ammonium chloropalladic acid solution to obtain a fourth intermediate product; The fourth intermediate product is immersed in a metal plating solution to obtain the wave-absorbing material, wherein the metal plating solution comprises a reducing agent and metal ions.

7. The metal-coated silicon carbide nanowire wave-absorbing material of claim 6, wherein, The volume ratio of sulfuric acid to nitric acid is (4-2):

1.

8. The metal-coated silicon carbide nanowire wave-absorbing material of claim 6, wherein, The volume ratio of trimethoxysilane solution, ethanol, acetic acid and deionized water is 1:(15-40):(0.1-1):(0.5-2).

9. The metal-coated silicon carbide nanowire wave-absorbing material of claim 6, wherein, The volume ratio of methacryloyloxyethyl trimethyl ammonium chloride to potassium persulfate aqueous solution is 1:(1.6-5).

10. Use of the metal-coated silicon carbide nanowire wave-absorbing material of claim 1 in electromagnetic absorption.

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