A method for preparing a graphene microwave absorbing composite material by using an electric explosion method

Abstract

The application belongs to the technical field of material preparation, and discloses a method for preparing a graphene microwave absorption composite material by using an electric explosion method, wherein graphite powder and metal magnetic alloy powder are mixed and stirred uniformly in proportion to obtain magnetic metal alloy-graphite mixed powder; the magnetic metal alloy-graphite mixed powder is pressed into a polyethylene carrier tape, the polyethylene carrier tape with the magnetic metal alloy-graphite mixed powder is loaded into a restraint hole of a rotating disc in an electric explosion chamber; the electric explosion chamber is vacuumized, argon is flushed, and the magnetic metal alloy-graphite mixed powder is electrically exploded by increasing an electric explosion voltage. The electric explosion method provided by the application has the characteristics of uniform product distribution, short preparation process period, green environmental protection and the like; the preparation of the graphene composite material by using the electric explosion method is a green, environmentally-friendly and sustainable development scheme, and will promote the wide application of the graphene composite material in the electromagnetic wave absorption field.

Description

Technical Field

[0001] This invention belongs to the field of materials preparation technology, and particularly relates to a method for preparing graphene microwave absorbing composite materials using an electro-explosion method. Background Technology

[0002] Currently, the widespread use of wireless communication and radar systems has caused electromagnetic pollution, which not only threatens human health but also seriously interferes with the normal operation of sensitive electronic devices. Therefore, developing electromagnetic wave absorbing materials with wide bandwidth, strong absorption, thinness, and light weight has become a hot research topic. Graphene, as a popular carbon material, possesses a unique physical structure and excellent thermodynamic and electrical properties. Combining it with magnetic nanoparticles such as iron-nickel can achieve complementary electromagnetic loss mechanisms, improve electromagnetic impedance matching characteristics, and optimize its electromagnetic wave absorption performance. Currently, there is considerable research on magnetic particle / graphene microwave absorbing composite materials. Many methods exist for preparing graphene-based microwave absorbing composite materials, such as hydrothermal methods, reduction methods, and freeze-drying methods, all of which are chemical preparation methods. These methods suffer from problems such as the use of large amounts of organic solvents, long preparation cycles, and low yields. Therefore, there is an urgent need to design a new method for preparing graphene microwave absorbing composite materials.

[0003] Based on the above analysis, the existing technologies have the following problems and shortcomings: First, conventional chemical preparation processes involve two steps: first, graphene is prepared, and then it is composited with metallic magnetic particles, making the process relatively cumbersome. Second, conventional preparation processes generate organic solvent waste, causing environmental pollution. Third, graphene sheets cannot be well dispersed during the composite process, resulting in uneven distribution of metallic magnetic particles within the graphene composite material. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a method for preparing graphene microwave absorbing composite materials using an electro-explosion method.

[0005] This invention is implemented as follows: a method for preparing graphene microwave absorbing composite material using an electro-explosion method. The method comprises: mixing graphite powder and metallic magnetic alloy powder in a specific ratio to obtain a magnetic metal alloy-graphite mixed powder; pressing 8 mg of the magnetic metal alloy-graphite mixed powder into a polyethylene carrier tape; subsequently, inserting 10 polyethylene carrier tapes containing the graphite-metal magnetic alloy mixed powder into the constraint holes of a turntable within an electro-explosion chamber; evacuating the electro-explosion chamber, purging it with argon gas, and increasing the electro-explosion voltage to electro-explode the magnetic metal alloy-graphite mixed powder.

[0006] Furthermore, during the electrical explosion, the high voltage causes the gas between the two electrodes to break down, forming an electric arc discharge. The plasma generated by the arc discharge causes drastic changes in temperature and density within the arc channel. As Joule heat is released, the arc channel expands outward, compressing the surrounding gas at supersonic speeds and generating a powerful shock wave. Under the influence of the high-temperature, high-pressure shock wave, the graphite powder expands and collides with the constraint holes, leading to breakage and peeling. Simultaneously, the metallic magnetic powder remelts or vaporizes and combines with the broken and peeled graphene to form a magnetic metal particle-graphene composite material.

[0007] Furthermore, the method for preparing graphene microwave absorbing composite materials using the electro-explosion method includes the following steps:

[0008] Step one involves mixing graphite powder and magnetic metal alloy powder in a specific ratio and grinding them evenly. A certain mass of the magnetic metal alloy-graphite mixed powder is then pressed into each carrier strip. This step ensures thorough and uniform mixing of the graphite powder and magnetic metal alloy powder, and by pressing the same mass of mixed powder into each carrier strip, guarantees that the product obtained from each electro-explosion is uniform.

[0009] Step two: After sequentially loading the carrier tape containing the magnetic metal alloy-graphite mixed powder into the constraint hole of the electric explosion equipment, the electric explosion chamber is sealed, a vacuum is drawn, and argon gas is introduced. The argon gas in the electric explosion chamber promotes gas discharge between the two electrodes and prevents oxidation of the magnetic metal alloy.

[0010] Step 3: The carrier belt containing the magnetic metal alloy-graphite mixed powder is connected to a high-voltage power supply under argon atmosphere protection, and the program is initiated to perform an electrical explosion. The energy generated by the electrical explosion breaks and peels off the graphite, while the magnetic metal alloy powder is instantly remelted or vaporized and combines with the broken and peeled graphene to form a composite material.

[0011] Furthermore, the preferred mixing ratio of graphite powder to metallic magnetic alloy powder in step one is 95:5.

[0012] Furthermore, the preferred mass of the magnetic metal alloy-graphite mixed powder in step one is 8 mg.

[0013] Furthermore, the metallic magnetic alloy powder in step one includes FeNi, CoFe, etc.

[0014] Furthermore, in step three, the high-voltage power supply is turned on and the voltage is adjusted to 12KV to charge the capacitor.

[0015] Furthermore, in the electro-explosion process of step three, a large current is introduced into the magnetic metal alloy-graphite mixed powder between the two electrodes to cause an explosion.

[0016] Furthermore, in step three, the instantaneous burst energy of the electric explosion is fully utilized to break and peel the graphite powder into graphene, while simultaneously melting or vaporizing the alloy particles doped in the graphite powder. As the shock wave from the electric explosion is ejected into the argon atmosphere, the broken graphene and the melted or vaporized particles combine to form a magnetic metal particle-graphene microwave absorbing composite material.

[0017] Another object of the present invention is to provide a graphene microwave absorbing composite material prepared by the method described above for preparing graphene microwave absorbing composite material using the electro-explosion method.

[0018] Based on the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by this invention are as follows:

[0019] The method provided by this invention is a physical process, which avoids the use of large amounts of organic solvents in traditional graphene composite material processes, and the preparation cycle is short.

[0020] This invention provides an electro-explosion method for preparing graphene microwave absorbing composite materials, which differs from currently reported chemical methods. This method offers advantages such as uniform product distribution, short preparation cycle, and environmental friendliness. The electro-explosion method yields magnetic metal particle-graphene composite materials with high microwave absorption performance. The electro-explosion method for preparing graphene composite materials provided by this invention is a green, environmentally friendly, and sustainable solution that will promote the widespread application of graphene composite materials in the field of electromagnetic wave absorption.

[0021] The expected benefits and commercial value of the technical solution of this invention after transformation are as follows: The graphene-based microwave absorbing composite material prepared by this invention can be applied in daily life to reduce electromagnetic pollution and interference. Simultaneously, in modern military warfare, the graphene-based microwave absorbing composite material can be used to achieve stealth of certain equipment and reduce radar cross-section.

[0022] The technical solution of this invention fills a technological gap in the industry both domestically and internationally: for the first time, a magnetic metal particle-graphene microwave absorbing composite material is prepared by physical electro-explosion method.

[0023] Does the technical solution of this invention solve a technical problem that people have long desired to solve but have never been able to achieve? This invention prepares graphene-based microwave absorbing composite materials through a physical electro-explosion method, avoiding the problems of complex production process, cumbersome process, high cost, and organic solvent pollution in the current preparation methods of graphene-based composite materials, so that the preparation of graphene-based composite materials can be green, environmentally friendly, efficient, and low cost. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a flowchart of a method for preparing graphene microwave absorbing composite materials using an electro-explosion method, provided in an embodiment of the present invention.

[0026] Figure 2 This is the XRD pattern of the graphene-based composite material containing 5wt% FeNi alloy provided in the embodiments of the present invention;

[0027] Figure 3 These are SEM and TEM images of the graphene-based composite material containing 5wt% FeNi alloy provided in the embodiments of the present invention;

[0028] Figure 4 This is a graph showing the microwave absorption characteristics of the graphene-based composite material containing 5wt% FeNi alloy, as provided in an embodiment of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0030] To address the problems existing in the prior art, this invention provides a method for preparing graphene microwave absorbing composite materials using an electro-explosion method. The invention will be described in detail below with reference to the accompanying drawings.

[0031] To enable those skilled in the art to fully understand how the present invention is specifically implemented, this section provides an explanatory description of the embodiments that expand upon the technical solutions of the claims.

[0032] In this invention, graphite powder and magnetic alloy powder are mixed and stirred evenly in a certain proportion to obtain a magnetic alloy-graphite mixed powder. 8 mg of the magnetic alloy-graphite mixed powder is pressed into a polyethylene carrier tape, and then 10 polyethylene carrier tapes containing the magnetic alloy-graphite mixed powder are loaded into the constraint holes of a rotating disk within an electric explosion chamber. Finally, the electric explosion chamber is evacuated, purged with argon gas, and the electric explosion voltage is increased to electrically explode the magnetic alloy-graphite mixed powder. During the electric explosion, a capacitor applies a high voltage to the electrodes near the constraint holes containing the magnetic alloy-graphite mixed powder. This invention introduces a large instantaneous current through gas discharge between the two electrodes, leading to arc discharge. The plasma generated by the arc discharge causes drastic changes in the temperature and density of the high-temperature arc channel. With the release of Joule heat, the arc channel expands outward and compresses the surrounding gas at supersonic speeds, generating a shock wave. Under the action of high temperature, high pressure, and shock wave, the graphite powder expands and collides with the interior of the constraint hole, thereby breaking and peeling off into graphene nanosheets. Similarly, the alloy particles also move at high speed in all directions under high temperature and pressure, randomly colliding with gas molecules or graphite particles in the explosion chamber and transforming into small droplets and gaseous particles. These small droplets and gaseous particles condense or adsorb onto graphene nanosheets to form magnetic metal particle-graphene composite materials.

[0033] The graphite powder used in this embodiment of the invention was provided by Beijing Gaoke New Materials Technology Co., Ltd., and its purity was 99.999%; the FeNi alloy powder used was provided by Changsha Tianjiu Metal Materials Co., Ltd., and its purity was 99.36%.

[0034] like Figure 1 As shown, the method for preparing graphene microwave absorbing composite materials using the electro-explosion method provided in this embodiment of the invention includes the following steps:

[0035] S101, graphite powder and metal magnetic alloy powder are thoroughly mixed in a certain proportion, and a certain mass of magnetic metal alloy-graphite mixed powder is pressed into each carrier strip.

[0036] S102, After sequentially loading the carrier belt containing magnetic metal alloy-graphite mixed powder into the constraint tube of the electric explosion equipment, the electric explosion chamber is sealed, a vacuum is drawn, and argon gas is filled.

[0037] S103, the carrier belt containing the magnetic metal alloy-graphite mixed powder is connected to a high-voltage power supply under argon atmosphere protection, and the program is started to perform electro-explosion.

[0038] S104, the instantaneous energy of the electric explosion breaks and peels graphite powder into graphene, while melting or vaporizing metallic magnetic alloy particles, which are then sprayed into the argon atmosphere with the electric explosion shock wave to form graphene composite materials.

[0039] In step S101 of this embodiment of the invention, the preferred mixing ratio of graphite powder and magnetic metal alloy powder is 95:5; the preferred mass of the magnetic metal alloy-graphite mixed powder is 8 mg.

[0040] The metallic magnetic alloy powder in step S101 provided in this embodiment of the invention includes FeNi, CoFe, etc., but is not limited to these two alloy powders.

[0041] In the electric explosion process of step S103 provided in the embodiment of the present invention, after charging with high voltage (12KV), a large current is introduced into the magnetic metal alloy-graphite mixed powder between the two electrodes to cause an explosion.

[0042] In the electro-explosion process provided in this embodiment of the invention, under the action of high temperature, high pressure and shock wave, graphite powder expands and collides with the internal collision constraint holes, thereby breaking and peeling off into graphene nanosheets. Metal powder is instantly remelted, sprayed, and settled into nanoparticles under high temperature and high pressure, which adhere to the broken graphene sheets to synthesize a composite material.

[0043] To demonstrate the inventiveness and technical value of the present invention, this section provides specific product or related technology application examples of the claimed technical solutions. A FeNi-graphene composite material with a FeNi content of 5 wt.% was prepared using an electro-explosion method, achieving an optimal reflection loss value of -25.8 dB, thus realizing excellent microwave absorption performance.

[0044] The embodiments of the present invention have achieved some positive results during the research and development or use process, and have indeed great advantages compared with the prior art. The following content describes the experimental process with data, charts and other information.

[0045] The preparation method of graphene-based microwave absorbing material provided in this embodiment of the invention includes the following steps:

[0046] S1, mix graphite powder and FeNi alloy powder in a ratio of 95:5, grind them in a mortar until they are mixed evenly and thoroughly to obtain a mixed powder containing 5wt.% FeNi alloy and 95wt.% graphite;

[0047] S2, Add an appropriate amount of PVA aqueous solution to the FeNi alloy-graphite mixed powder, stir evenly and set aside;

[0048] S3, press 8mg of FeNi alloy-graphite mixed powder into each polyethylene carrier belt;

[0049] S4. After sequentially loading the carrier belt containing FeNi alloy-graphite mixed powder into the constraint tube of the electric explosion equipment, the electric explosion chamber is sealed.

[0050] S5, the carrier belt containing FeNi alloy-graphite mixed powder is started under a protective atmosphere to perform an electric explosion. The instantaneous shock wave of the electric explosion breaks and peels the graphite powder into graphene, while melting or breaking the alloy doped in the graphite powder. As the electric explosion shock wave is sprayed into the argon atmosphere, it is deposited on the broken graphene to form FeNi alloy-graphene composite material.

[0051] like Figure 2 The XRD diffraction pattern of the FeNi alloy-graphene composite material after the electrical explosion is shown. As can be seen from the figure, strong peaks appear at 2θ = 26.38° and 54.54°, corresponding to the (002) and (004) crystal planes of Grphite-2H, respectively. The three characteristic peaks at 2θ = 50.79°, 43.60°, and 74.67° correspond to the (200), (111), and (220) crystal planes of face-centered cubic (FCC) FeNi, respectively, which are consistent with the FeNi phase on the JCPDS card (47-1405). The peak at 2θ = 77.69° corresponds to the (110) crystal plane of Grphite-3R. A peak at 2θ = 44.83° indicates the Ni2O3 phase, and a peak at 2θ = 43.36° indicates the NiFe2O4 phase.

[0052] like Figure 3 The images shown are TEM and SEM images of the FeNi alloy-graphene composite material after the electrical explosion. Figure 3 (a) is a TEM image of the composite material. It can be seen that the graphite powder exists in two forms after the electrical explosion: Figure 3 (a) is lamellar at position 1 and clustered at position 2. Figure 3 (b) is Figure 3 (a) The image at high resolution shows that the number of graphene sheets after the electro-explosion is approximately 10. Figure 3 SEM images (c) to (d) show that the products after electro-explosion are finer, more flocculent, and uniformly distributed. This introduces more porosity into the material, resulting in lower density and more polarization interfaces. The electro-exploded metal powder is remelted under high temperature and pressure and deposited on the surface of the fine graphene powder. The metallic magnetic particles introduced into the graphene can achieve complementary electromagnetic loss mechanisms, optimizing the electromagnetic wave absorption performance of the graphene composite material.

[0053] like Figure 4 The figure shows the microwave absorption characteristics of the FeNi alloy-graphene composite material after an electric explosion. As can be seen from the figure, the matching thickness of this composite material approximately satisfies a 1 / 4 destructive interference relationship with the frequency. Additionally, the impedance matching |Z in / Z0| is one of the important parameters for determining microwave absorption performance. The closer this value is to 1, the more incident microwaves are penetrated into the material and converted into heat or other forms of energy. When the matching thickness is 1.0 mm, its value is closest to 1, and the reflection loss value is optimal at -25.4 dB.

[0054] In summary, the method of electro-explosion provided by the embodiments of the present invention can obtain a magnetic metal particle-graphene microwave absorbing composite material with high microwave absorption performance.

[0055] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing graphene microwave absorbing composite materials using an electro-explosion method, characterized in that, include: Graphite powder and magnetic metal alloy powder are mixed and stirred evenly in a certain proportion to obtain magnetic metal alloy-graphite mixed powder; the magnetic metal alloy-graphite mixed powder is pressed into a polyethylene carrier belt, and then the polyethylene carrier belt containing the magnetic metal alloy-graphite mixed powder is loaded into the constraint hole of the turntable in the electric explosion chamber; the electric explosion chamber is evacuated, filled with argon gas, and the electric explosion voltage is increased to perform electric explosion on the graphite-magnetic metal alloy mixed powder. The method for preparing graphene microwave absorbing composite materials using the electro-explosion method includes the following steps: Step 1: Mix graphite powder and magnetic metal alloy powder in a certain proportion, and press a certain mass of magnetic metal alloy-graphite mixed powder into each carrier belt. Step 2: After sequentially loading the carrier belt containing magnetic metal alloy-graphite mixed powder into the constraint hole of the electric explosion equipment, seal the electric explosion chamber, evacuate, and fill with argon gas. Step 3: Connect the carrier belt containing the magnetic metal alloy-graphite mixed powder to a high-voltage power supply under argon atmosphere protection, and start the program to perform electro-explosion. The metallic magnetic alloy powder in step one includes FeNi and CoFe.

2. The method for preparing graphene microwave absorbing composite materials using the electro-explosion method as described in claim 1, characterized in that, During the electric explosion, the high voltage causes the gas between the two electrodes to break down, forming an electric arc discharge. The plasma generated by the electric arc discharge causes drastic changes in temperature and density within the arc channel. As Joule heat is released, the arc channel expands outward and compresses the surrounding gas at supersonic speed, generating a strong shock wave. Under the action of the high temperature and high pressure shock wave, the graphite powder expands and collides with the constraint hole, resulting in breakage and peeling. The metallic magnetic powder is remelted or vaporized and combines with the broken and peeled graphene to form a metallic magnetic particle-graphene composite material.

3. The method for preparing graphene microwave absorbing composite materials using the electro-explosion method as described in claim 1, characterized in that, The mixing ratio of graphite powder to magnetic metal alloy powder in step one is 95:5; the mass of the magnetic metal alloy-graphite mixed powder is 8 mg.

4. The method for preparing graphene microwave absorbing composite materials using the electro-explosion method as described in claim 1, characterized in that, The polyethylene carrier belt consists of 10 pieces.

5. The method for preparing graphene microwave absorbing composite materials using the electro-explosion method as described in claim 1, characterized in that, In step three, the high-voltage charging and discharging system is turned on, the voltage is adjusted to 12KV, and the capacitor is charged. In the electro-explosion process of step three, after high voltage is applied, a large current is introduced into the magnetic metal alloy-graphite mixed powder between the two electrodes to cause an explosion.

6. The method for preparing graphene microwave absorbing composite materials using the electro-explosion method as described in claim 1, characterized in that, In step three, the electric explosion procedure is initiated. During the electric explosion, the instantaneous burst energy of the electric explosion is fully utilized to break and peel the graphite powder into graphene. At the same time, the alloy particles doped in the graphite powder are melted or vaporized. As the electric explosion shock wave is sprayed into the argon atmosphere, it is deposited on the broken graphene to form a magnetic metal particle-graphene microwave absorbing composite material.

7. The method for preparing graphene microwave absorbing composite materials using the electro-explosion method as described in claim 1, characterized in that, During the electrical explosion process in step three, under the action of high temperature, high pressure and shock wave, the graphite powder expands and collides with the internal collision constraint hole, thereby breaking and peeling into graphene nanosheets; the metal powder is instantly remelted, sprayed and settled into nanoparticles under high temperature and high pressure, which are attached to the broken graphene sheets to synthesize composite materials.

8. A graphene microwave absorbing composite material prepared by the method of preparing graphene microwave absorbing composite material by electro-explosion method according to any one of claims 1 to 7.

Images