Composite magnetic wave-absorbing material and preparation method thereof

Abstract

The application belongs to the technical field of wave-absorbing materials, and relates to a composite magnetic wave-absorbing material and a preparation method thereof. The application prepares a graphene material with a three-dimensional wrinkle structure by using an improved gas phase deposition method, further performs alkali etching to form pores, adds functional groups by oxidation, and prepares the composite magnetic wave-absorbing material by using a coprecipitation method. The wave-absorbing material provided by the application has excellent electromagnetic wave absorption performance in full-wave band testing, and some frequency points can reach-43dB. The wave-absorbing material provided by the application has multiple modes of dielectric loss, magnetic loss and structural loss, and is also greatly improved in terms of light weight and thin layer.

Description

Technical Field

[0001] This invention belongs to the field of microwave absorbing materials technology, and relates to a composite magnetic microwave absorbing material and its preparation method. Background Technology

[0002] Radar technology has made rapid progress since World War II. With the widespread application of radar reconnaissance technology in situational defense systems, the use of stealth technology to avoid radar identification, location, and tracking, and to improve the battlefield survivability of combat targets, has increasingly become a research focus for various countries. Radar-absorbing materials are functional materials that can attenuate incident electromagnetic waves and convert their electromagnetic energy into other forms of energy dissipation, or change the phase of electromagnetic waves so that they disappear due to interference. With the emergence of advanced military equipment such as the F-117 stealth fighter, the B-2 stealth bomber, the U-2 high-altitude reconnaissance aircraft, and the "Sea Shadow" experimental ship, radar-absorbing materials have demonstrated strong advantages in military applications.

[0003] Graphene's unique two-dimensional structure with a single atom thickness gives it excellent properties such as light weight, large specific surface area, good conductivity, and high dielectric constant. In addition, the numerous dangling bonds in graphene make it easier to attenuate electromagnetic waves under the influence of an electric field due to the polarization relaxation of the outer electromagnetic layer. Furthermore, chemically prepared graphene has a large number of oxygen-containing functional groups and defects. At the same time, defects and functional groups can reduce the conductivity of graphene and generate localized states of the Fermi level, which is beneficial for the absorption and attenuation of electromagnetic waves.

[0004] Graphene's high dielectric loss leads to poor impedance matching and reduced microwave absorption performance. This also suggests the potential to achieve the desired dielectric loss with lower filler content, demonstrating sufficient electromagnetic wave dissipation while simultaneously achieving impedance matching. However, the tendency for graphene sheets to aggregate and stack between layers makes effective dispersion difficult, significantly reducing the effective contact area for electromagnetic wave interaction and hindering the full realization of its electromagnetic wave absorption performance. Therefore, there is a need to develop a microwave absorbing material that combines structural, electrical, and magnetic losses, meeting the requirements of being "thin, wide, lightweight, and strong." Summary of the Invention

[0005] The purpose of this invention is to develop a microwave absorbing material that combines structural loss, electrical loss, and magnetic loss, thereby meeting the requirements of "thin, wide, light, and strong" for novel microwave absorbing materials.

[0006] To address this need in the field, this application provides a composite magnetic microwave absorbing material and its preparation method.

[0007] On one hand, the present invention relates to a method for preparing a composite magnetic microwave absorbing material, which includes: bubbling hydrocarbon gas into a molten catalytic metal liquid, wherein three-dimensional wrinkled graphene is formed during the ascent of the hydrocarbon gas;

[0008] The three-dimensional folded graphene was subjected to high-temperature treatment with potassium hydroxide to obtain three-dimensional folded porous graphene.

[0009] The three-dimensional folded porous graphene, potassium permanganate, and concentrated sulfuric acid were mixed and stirred to react. Water and hydrogen peroxide were then added to obtain three-dimensional folded porous multifunctional graphene.

[0010] A water-soluble salt of a magnetic metal is dissolved in water with ferric chloride to obtain a metal salt solution. The three-dimensional pleated porous multifunctional graphene is mixed with the metal salt solution, and the pH is maintained above 8. After adding hydrazine hydrate and reacting at 80°C for 4 hours, the composite magnetic absorbing material is obtained.

[0011] Furthermore, in the preparation method of the composite magnetic microwave absorbing material provided by the present invention, the molten catalytic metal liquid is molten copper.

[0012] Furthermore, in the preparation method of the composite magnetic absorbing material provided by the present invention, the hydrocarbon gas includes: methane, ethane, propane, ethylene, acetylene, and natural gas.

[0013] Furthermore, in the preparation method of the composite magnetic absorbing material provided by the present invention, the magnetic metal includes: magnesium, manganese, iron, cobalt, nickel, copper, zinc, cadmium, barium, strontium, and lead.

[0014] Furthermore, in the preparation method of the composite magnetic absorbing material provided by the present invention, the ratio of the three-dimensional wrinkled graphene to the potassium hydroxide is 0.5-1.5:0.1-0.5 by mass.

[0015] Furthermore, in the preparation method of the composite magnetic absorbing material provided by the present invention, each 0.5-1.5g of the three-dimensional pleated porous graphene is combined with 1.5-3.5g of potassium permanganate and 15-30mL of concentrated sulfuric acid.

[0016] Furthermore, in the preparation method of the composite magnetic absorbing material provided by the present invention, the three-dimensional wrinkled graphene is neutralized by ferric chloride corrosion, washing, and filtration.

[0017] Furthermore, in the preparation method of the composite magnetic absorbing material provided by the present invention, the three-dimensional folded porous multifunctional graphene and the metal salt solution are washed and ultrasonically dispersed before mixing.

[0018] Furthermore, in the preparation method of the composite magnetic absorbing material provided by the present invention, ammonia water is used to maintain the pH greater than 8.

[0019] On the other hand, the present invention relates to a composite magnetic absorbing material, which is prepared by the above-mentioned method for preparing composite magnetic absorbing materials.

[0020] The absorbing material provided by this invention exhibits excellent electromagnetic wave absorption performance across the entire frequency band, reaching -43dB at some frequencies. This absorbing material combines dielectric loss, magnetic loss, and structural loss modes, and also achieves significant improvements in terms of lightweight and thinness. Therefore, this invention further claims protection for a device for absorbing antenna radiation waves, comprising the aforementioned composite magnetic absorbing material.

[0021] Compared with the prior art, the present invention has the following beneficial effects or advantages:

[0022] This invention provides a composite magnetic absorbing material, which is formed by a simple co-precipitation process to combine graphene and magnetic materials. Compared with traditional two-dimensional sheet graphene, the processed three-dimensional porous graphene exhibits more outstanding structural and dielectric losses. Compared with traditional magnetic materials, the special properties of graphene excite more of its own magnetic losses. At the same time, the manufacturing process is simple, without the need for complex processes such as high-temperature calcination, making it easy to mass-produce and promote. Attached Figure Description

[0023] Figure 1 The microstructure of three-dimensional wrinkled graphene.

[0024] Figure 2 This is Raman spectroscopy data for three-dimensional wrinkled graphene.

[0025] Figure 3 The microstructure of the composite magnetic absorbing material.

[0026] Figure 4 These are Raman test data for composite magnetic absorbing materials.

[0027] Figure 5 Elemental content analysis of composite magnetic microwave absorbing materials.

[0028] Figure 6 BaFe magnetic material 12 O 19 Test results of the microwave absorption performance of a composite magnetic microwave absorbing material with a mass ratio of 10:1 to three-dimensional folded porous graphene.

[0029] Figure 7 BaFe magnetic material 12 O 19 Test results of the absorption performance of a composite magnetic absorbing material with a mass ratio of 5:1 to three-dimensional pleated porous graphene.

[0030] Figure 8 BaFe magnetic material12 O 19 Test results of the microwave absorption performance of a composite magnetic microwave absorbing material with a mass ratio of 2:1 to three-dimensional pleated porous graphene.

[0031] Figure 9 BaFe magnetic material 12 O 19 The results of the absorption performance test. Detailed Implementation

[0032] The technical solution of the present invention will be described below with reference to the embodiments. However, the present invention is not limited to the following embodiments.

[0033] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention.

[0034] Unless otherwise specified, the experimental and detection methods described in the following embodiments are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0035] Example 1

[0036] This embodiment provides a preparation step for a composite magnetic microwave absorbing material.

[0037] Argon gas is introduced into the reaction vessel as a protective gas to raise the temperature to 1100℃, allowing the copper to enter a molten state. Methane gas is then introduced, and as the gas microbubbles rise in the molten copper, a mixture of copper slag and three-dimensional graphene is formed. Ferric chloride is used to corrode the copper slag, and the mixture is washed, filtered, and dried to obtain three-dimensional wrinkled graphene.

[0038] 10g of three-dimensional wrinkled graphene and 2g of sheet-like potassium hydroxide were mixed evenly by grinding and placed in a reaction iron tank. The iron tank was placed in an iron tube furnace under nitrogen protection and stabilized at 800℃ for 1 hour. The sample was then removed, washed, filtered, dried and ground to obtain three-dimensional wrinkled porous graphene.

[0039] 10g of three-dimensional wrinkled porous graphene, 27g of potassium permanganate, and 200mL of concentrated sulfuric acid were mixed and magnetically stirred at room temperature for 2 hours. The water bath was then heated to 45℃, and magnetic stirring was continued for 0.5 hours. Deionized water was slowly added while stirring, and the mixture was then transferred to a 2000mL beaker. 1000mL of deionized water was added, and excess hydrogen peroxide was added until no more bubbles appeared. The mixture was washed and filtered until neutral to obtain three-dimensional wrinkled porous multifunctional graphene.

[0040] 23.5g of barium nitrate and 175.1g of ferric chloride were dissolved in water to obtain a metal salt solution. Three-dimensional pleated porous multifunctional graphene was ultrasonically dispersed for 30 min. The dissolved barium iron ion solution and the three-dimensional pleated porous multifunctional graphene dispersion were mixed and adjusted to alkalinity with ammonia. 25mL of hydrazine hydrate was added, and the mixture was reacted in a water bath at 80℃ for 4 hours, and then allowed to stand overnight.

[0041] The sample, after standing overnight, was filtered, washed, dried at 120°C, and ground to obtain three-dimensional wrinkled porous graphene and magnetic material BaFe. 12 O 19 A composite magnetic absorbing material with a mass ratio of 1:10.

[0042] Example 2

[0043] This embodiment provides a preparation step for a composite magnetic microwave absorbing material.

[0044] Argon gas is introduced into the reaction vessel as a protective gas to raise the temperature to 1100℃, allowing the copper to enter a molten state. Methane gas is then introduced, and as the gas microbubbles rise in the molten copper, a mixture of copper slag and three-dimensional graphene is formed. Ferric chloride is used to corrode the copper slag, and the mixture is washed, filtered, and dried to obtain three-dimensional wrinkled graphene.

[0045] 10g of three-dimensional wrinkled graphene and 2g of sheet-like potassium hydroxide were mixed evenly by grinding and placed in a reaction iron tank. The iron tank was placed in an iron tube furnace under nitrogen protection and stabilized at 800℃ for 1 hour. The sample was then removed, washed, filtered, dried and ground to obtain three-dimensional wrinkled porous graphene.

[0046] 10g of three-dimensional wrinkled porous graphene, 27g of potassium permanganate, and 200mL of concentrated sulfuric acid were mixed and magnetically stirred at room temperature for 2 hours. The water bath was then raised to 45℃ and magnetic stirring was continued for 0.5 hours. Deionized water was slowly added while stirring. The mixture was then transferred to a 2000mL beaker, and 1000mL of deionized water was added. Excess hydrogen peroxide was added until no more bubbles appeared. The mixture was washed and filtered until neutral.

[0047] 11.8 g of barium nitrate and 87.6 g of ferric chloride were completely dissolved in deionized water. Three-dimensional wrinkled porous multifunctional graphene was ultrasonically dispersed for 30 min. The dissolved barium ferric ion solution and the three-dimensional wrinkled porous multifunctional graphene dispersion were mixed, and the mixture was adjusted to alkalinity with ammonia. 25 mL of hydrazine hydrate was added, and the mixture was reacted in a water bath at 80 °C for 4 hours, and then allowed to stand overnight.

[0048] The sample, after standing overnight, was filtered, washed, dried at 120°C, and ground to obtain three-dimensional wrinkled porous graphene and magnetic material BaFe. 12 O 19 A composite magnetic absorbing material with a mass ratio of 1:5.

[0049] Example 3

[0050] This embodiment provides a preparation step for a composite magnetic microwave absorbing material.

[0051] Argon gas is introduced into the reaction vessel as a protective gas to raise the temperature to 1100℃, allowing the copper to enter a molten state. Methane gas is then introduced, and as the gas microbubbles rise in the molten copper, a mixture of copper slag and three-dimensional graphene is formed. Ferric chloride is used to corrode the copper slag, and the mixture is washed, filtered, and dried to obtain three-dimensional wrinkled graphene.

[0052] 10g of three-dimensional wrinkled graphene and 2g of sheet-like potassium hydroxide were mixed evenly by grinding and placed in a reaction iron tank. The iron tank was placed in an iron tube furnace under nitrogen protection and stabilized at 800℃ for 1 hour. The sample was then removed, washed, filtered, dried and ground to obtain three-dimensional wrinkled porous graphene.

[0053] 10g of three-dimensional wrinkled porous graphene, 27g of potassium permanganate, and 200mL of concentrated sulfuric acid were mixed and magnetically stirred at room temperature for 2 hours. The water bath was then raised to 45℃ and magnetic stirring was continued for 0.5 hours. Deionized water was slowly added while stirring. The mixture was then transferred to a 2000mL beaker, and 1000mL of deionized water was added. Excess hydrogen peroxide was added until no more bubbles appeared. The mixture was washed and filtered until neutral.

[0054] 4.7g of barium nitrate and 35.0g of ferric chloride were completely dissolved in deionized water.

[0055] Three-dimensional pleated porous multifunctional graphene was ultrasonically dispersed for 30 min. The dissolved barium iron ion solution and the three-dimensional pleated porous multifunctional graphene dispersion were mixed, and the mixture was adjusted to alkalinity with ammonia. 25 mL of hydrazine hydrate was added, and the mixture was reacted in a water bath at 80 °C for 4 hours, and then allowed to stand overnight.

[0056] The sample, after standing overnight, was filtered, washed, dried at 120°C, and ground to obtain three-dimensional wrinkled porous graphene and magnetic material BaFe. 12 O 19 A composite magnetic absorbing material with a mass ratio of 1:2.

[0057] Comparative Examples

[0058] This embodiment provides a magnetic absorbing material BaFe. 12 O 19 The preparation steps.

[0059] 4.7g of barium nitrate and 35.0g of ferric chloride were completely dissolved in deionized water.

[0060] The dissolved barium iron ion solution was adjusted to alkalinity with ammonia water, reacted in a water bath at 80°C for 4 hours, and then left to stand overnight.

[0061] The sample, after being left to stand overnight, was filtered, washed, dried at 120°C, and ground to obtain pure magnetic material BaFe. 12 O 19 Wave-absorbing materials.

[0062] Microscopic morphology and elemental analysis were performed using a Hitachi S-4800 high-resolution field emission scanning electron microscope (SEM); Raman analysis was performed using a Renishaw laser Raman spectrometer (in Via Reflex); electromagnetic parameter measurements were performed by mixing the absorbent with a low dielectric constant material (such as paraffin) and applying the waveguide method using an HP8722ES vector network analyzer.

[0063] Figure 1 The microstructure of three-dimensional wrinkled graphene is shown. Figure 1 It can be seen that the graphene prepared by the improved CVD is an independent three-dimensional wrinkled graphene.

[0064] Figure 2 This is Raman spectroscopy data for three-dimensional wrinkled graphene. (Source: [Insert data here]) Figure 2 It can be seen that by using Raman spectroscopy and the position of graphene characteristic peaks, it can be determined that the sample has a single-layer graphene structure with very few graphene defects and high quality.

[0065] Figure 3 The microstructure of the composite magnetic absorbing material is shown. Figure 3 It can be seen that, in comparison Figure 1 As a result, nanoscale ferrites adhered to the graphene surface.

[0066] Figure 4 These are Raman test data for composite magnetic absorbing materials. Figure 4 It can be seen that the graphene Raman spectroscopy of the ferrite composite showed obvious defect peaks.

[0067] Figure 5 Elemental content analysis of the composite magnetic absorbing material. The specific results of the elemental content of the composite magnetic absorbing material prepared in this invention are shown in Table 1.

[0068] Table 1. Elemental content analysis of composite magnetic microwave absorbing materials

[0069]

[0070] From Table 1 and Figure 5 It can be seen that the elements contained in the composite material and their content indirectly prove the existence of magnetic materials and carbon materials.

[0071] The absorption performance of Examples 1-3 and the comparative examples was tested, and the results are as follows: Figures 6-9 As shown.

[0072] Depend on Figures 6-9 It is known that when only magnetic ferrite is present, the absorption performance is not good. Figure 9 The thickness does not reach -10dB; however, when a small amount of graphene is added, the thickness does not reach this level. Figure 6 The absorption performance is significantly improved; when the graphene content is further increased, that is... Figure 7 The absorption performance reaches its optimal level; at a thickness of 3.0 mm, it achieves -43 dB at a frequency of 6.8 GHz, meaning it absorbs over 99.99% of electromagnetic waves. Further increasing the graphene content... Figure 8 On the contrary, the absorption performance decreases. Overall, there is an optimal ratio between graphene and magnetic ferrite.

[0073] As described above, the present invention can be well implemented. The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, all kinds of changes and improvements made by those skilled in the art to the technical solutions of the present invention should fall within the protection scope defined by the present invention.

Claims

1. A method for preparing a composite magnetic microwave absorbing material, characterized in that, include: Hydrocarbon gas is bubbled into a molten catalytic metal liquid, and three-dimensional wrinkled graphene is formed as the hydrocarbon gas rises. The three-dimensional folded graphene and potassium hydroxide are subjected to high temperature treatment to obtain three-dimensional folded porous graphene; the mass ratio of the three-dimensional folded graphene to the potassium hydroxide is 0.5~1.5:0.1~0.

5. The three-dimensional folded porous graphene, potassium permanganate, and concentrated sulfuric acid are mixed and stirred to react. Water and hydrogen peroxide are then added to obtain three-dimensional folded porous multifunctional graphene. Each 0.5~1.5g of the three-dimensional folded porous graphene is combined with 1.5~3.5g of potassium permanganate and 15~30mL of concentrated sulfuric acid. A water-soluble salt of a magnetic metal is dissolved in water with ferric chloride to obtain a metal salt solution. The three-dimensional pleated porous multifunctional graphene is mixed with the metal salt solution, and the pH is maintained above 8 using ammonia water. After adding hydrazine hydrate and reacting at 80°C for 4 hours, the composite magnetic absorbing material is obtained. The three-dimensional wrinkled graphene is neutralized by ferric chloride etching, washing, and filtration; the three-dimensional wrinkled porous multifunctional graphene is washed and ultrasonically dispersed before being mixed with the metal salt solution.

2. The method for preparing the composite magnetic absorbing material according to claim 1, characterized in that, The molten catalytic metal liquid is molten copper.

3. The method for preparing the composite magnetic absorbing material according to claim 1, characterized in that, The hydrocarbon gases include: methane, ethane, propane, ethylene, acetylene, and natural gas.

4. The method for preparing the composite magnetic absorbing material according to claim 1, characterized in that, The magnetic metals include: magnesium, manganese, iron, cobalt, nickel, copper, zinc, cadmium, barium, strontium, and lead.

5. A composite magnetic wave-absorbing material, characterized in that, The composite magnetic absorbing material is prepared using the preparation method described in any one of claims 1-4.

6. A device for absorbing antenna-radiated waves, characterized in that, Includes the composite magnetic wave-absorbing material as described in claim 5.

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