A carbon-based magnetic composite absorbing material and its preparation method and application

Abstract

The present invention relates to the technical field of absorbing materials, and in particular to a carbon-based magnetic composite absorbing material and a preparation method and application thereof. The preparation method of the carbon-based magnetic composite absorbing material comprises the following steps: preparation of a magnetic matrix; pretreatment; plasma enhanced chemical vapor deposition; and cooling treatment. The preparation method of the present invention can realize the rapid preparation of a carbon-based magnetic composite absorbing material, and the prepared carbon-based magnetic composite absorbing material has good absorbing performance. The preparation of carbon-based magnetic composite absorbing materials with different dielectric responses and absorbing performances can be realized by adjusting the preparation process parameters. The preparation method has simple process, strong operability, high production efficiency and low production cost.

Description

Technical Field

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

[0002] Due to the increasingly serious electromagnetic pollution, "thin, wide, light and strong" high-efficiency microwave absorbing materials have become a hot topic of research. Among the many absorbing materials, carbon-based magnetic composite materials are favored by researchers because they have the advantages of both magnetic loss and dielectric loss, light weight, adjustable impedance matching, and relatively stable physical and chemical properties.

[0003] At present, the preparation methods of carbon-based magnetic composite materials mainly include the following:

[0004] (1) Solvothermal method: first prepare the precursors of organic carbon source and magnetic particles, and then obtain carbon-based magnetic composite powder by high-temperature carbonization; (2) Arc discharge plasma technology: use magnetic metal rods and carbon rods as positive and negative electrodes, and prepare carbon-based magnetic composite powder by arc discharge; (3) Other preparation methods: such as electrospinning, atomic layer deposition, chemical vapor deposition, etc.

[0005] However, the bonding strength between the carbon component introduced by high-temperature carbonization or chemical bonding and the magnetic component is insufficient, resulting in poor wave absorption performance that cannot be compared with the performance of commercial magnetic powders; furthermore, the preparation process is complex and the preparation efficiency is low.

[0006] In view of this, and in view of the above deficiencies in the prior art, the present invention provides a carbon-based magnetic composite absorbing material and a preparation method and application thereof, which can quickly realize the preparation of a carbon-based magnetic composite absorbing material with excellent absorbing performance. Summary of the invention

[0007] (1) Technical issues to be solved

[0008] The purpose of the present invention is to provide a method for preparing a carbon-based magnetic composite absorbing material to solve the problems of poor absorbing performance and low preparation efficiency of traditional preparation methods.

[0009] (2) Technical solution

[0010] In order to solve the above problems, the present invention provides a method for preparing a carbon-based magnetic composite absorbing material, which comprises the following steps:

[0011] S1. Preparation of magnetic substrate: laying the magnetic substrate flat on a high temperature resistant substrate, placing it in a furnace tube of a heating furnace of a PECVD device, and then evacuating the furnace tube to a vacuum;

[0012] S2, pretreatment: heating the heating furnace to the growth temperature of the magnetic substrate, then introducing H2 to pretreat the magnetic substrate, and simultaneously opening a plasma source to the magnetic substrate to remove an oxide layer on the surface of the magnetic substrate;

[0013] S3, plasma enhanced chemical vapor deposition: introducing a carbon source and an auxiliary gas into the heating furnace to in-situ grow a nano-carbon layer on the magnetic substrate;

[0014] S4, cooling treatment: stop introducing the carbon source and turn off the plasma source, introduce inert gas into the heating furnace to cool it to room temperature, so as to obtain a carbon-based magnetic composite absorbing material.

[0015] Furthermore, in step S1, the magnetic matrix is ​​a high temperature resistant magnetic metal spherical powder or flaky powder, and the particle size of the magnetic matrix is ​​1 to 50 μm.

[0016] Furthermore, in step S1, the magnetic matrix is ​​Ni powder or FeCo powder.

[0017] Furthermore, in step S1, the vacuum degree of the vacuum pump is below 0.1 Pa.

[0018] Furthermore, in step S2, the heating rate is 10-20°C / min, and the growth temperature is 600-900°C.

[0019] Furthermore, in step S2, the radio frequency power of the plasma source is 50 to 500 W, the flow rate of H2 is 10 to 40 sccm, the gas pressure in the heating furnace is 1 to 15 Pa, and the pretreatment time is 10 to 30 min.

[0020] Furthermore, in step S3, the carbon source is CH4, and the auxiliary gas is one or more of H2, N2, and Ar.

[0021] Furthermore, in step S3, the radio frequency power of the plasma source is 50-500 W, the total flow rate of the carbon source and the auxiliary gas is 5-50 sccm, the gas pressure of the in-situ growth is 1-15 Pa, and the time of the in-situ growth is 30-300 min.

[0022] Another aspect of the present invention provides a carbon-based magnetic composite absorbing material prepared by the above preparation method, and application of the carbon-based magnetic composite absorbing material as an absorbing material or absorbing agent in the field of electromagnetic wave technology.

[0023] (3) The beneficial effects of the present invention are as follows:

[0024] The invention realizes the rapid preparation of carbon-based magnetic composite wave absorbing material through magnetic matrix preparation-pretreatment-PECVD-cooling treatment.

[0025] A. The nano-carbon layer is grown in situ using magnetic powder as the matrix. The magnetic loss performance of the magnetic powder remains basically unchanged after high temperature treatment during the PECVD growth process.

[0026] B. Through the in-situ composite between the carbon nanolayer and the magnetic powder, the interface contact between the carbon layer and the magnetic micropowder particles is achieved, and the interface bonding force is improved. Therefore, the wave absorption performance of the composite powder is significantly enhanced compared with the original powder.

[0027] C. The preparation method of the present invention has a simple process flow and strong operability. The structure of the nanocarbon layer can be effectively adjusted by adjusting the growth process parameters, thereby obtaining a carbon-based magnetic composite absorbing material with different dielectric responses and absorbing properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 These are SEM images of the carbon-based magnetic composite absorbing material prepared by the preparation method of Example 1 of the present invention at different magnifications.

[0029] Figure 2 It is a comparison chart of the absorbing performance of the composite absorbing material prepared in Example 1 of the present invention and the raw material Ni powder.

[0030] Figure 3 These are SEM images of the composite absorbing material prepared by the preparation method of Example 2 of the present invention at different magnifications, (a) is the SEM image of the raw material FeCo powder, (b) (c) are SEM images of the carbon-based magnetic composite absorbing material prepared in Example 2 at different magnifications.

[0031] Figure 4 It is a comparison chart of the absorbing performance of the composite absorbing material prepared in Example 2 of the present invention and the raw material FeCo powder. DETAILED DESCRIPTION

[0032] The following detailed description of the embodiments of the present invention is provided in conjunction with the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present invention, but cannot be used to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments.

[0033] like Figures 1 to 4 As shown, the carbon-based magnetic composite absorbing material and its preparation method involved in this embodiment and its application as absorbing material or absorbing agent in the field of electromagnetic wave technology include:

[0034] A method for preparing a carbon-based magnetic composite absorbing material, the preparation method is carried out according to the following steps:

[0035] S1. Preparation of magnetic substrate: laying the magnetic substrate flat on a high temperature resistant substrate, placing it in a furnace tube of a heating furnace of a PECVD device, and then evacuating the furnace tube to a vacuum;

[0036] S2, pretreatment: heating the heating furnace to the growth temperature of the magnetic substrate, then introducing H2 to pretreat the magnetic substrate, and simultaneously turning on the plasma source to remove the oxide layer on the surface of the magnetic substrate;

[0037] S3, plasma enhanced chemical vapor deposition: introducing a carbon source and an auxiliary gas into the heating furnace to in-situ grow a nano-carbon layer on the magnetic substrate;

[0038] S4, cooling treatment: stop introducing the carbon source and turn off the plasma source, introduce inert gas into the heating furnace to cool it to room temperature, so as to obtain a carbon-based magnetic composite absorbing material.

[0039] It should be noted that PECVD is the abbreviation for plasma assisted chemical vapor deposition.

[0040] Specifically, in step S1, the magnetic matrix is ​​a high temperature resistant magnetic metal powder, the powder is spherical or flaky, and the particle size of the magnetic matrix is ​​1 to 50 μm. Preferably, the magnetic matrix is ​​one or more of Ni powder, Fe powder, FeNi powder, and FeCo powder.

[0041] Specifically, in step S1, the high temperature resistant substrate is a quartz glass substrate or a corundum substrate, the heating furnace is a high temperature tube furnace, and the vacuum degree of the vacuum is below 0.1 Pa.

[0042] Specifically, in step S2, the heating furnace is first heated to the growth temperature of the magnetic substrate, the growth temperature is 600-900°C, preferably, the growth temperature is 700°C or 775°C, and the heating rate is 10-20°C / min, preferably, the heating rate is 15°C / min;

[0043] Then, H2 is introduced to pretreat the magnetic substrate, and the plasma source is turned on at the same time. The RF power of the plasma source is 50-500W, preferably, the RF power of the plasma source is 300W; the flow rate of H2 is 10-40sccm, preferably, the flow rate of H2 is 20sccm; the gas pressure in the heating furnace is 1-15Pa, and the pretreatment time is 10-30min, preferably, the pretreatment time is 20min, so as to remove the oxide layer on the surface of the magnetic substrate.

[0044] Specifically, in step S3, a carbon source and an auxiliary gas are introduced into the heating furnace at the same time, wherein the carbon source is CH4, and the auxiliary gas is one of H2, N2, and Ar. Preferably, the auxiliary gas is H2.

[0045] Specifically, in step S3, the RF power of the plasma source is 50 to 500 W, preferably, the RF power of the plasma source is 500 W; the total flow rate of the carbon source and the auxiliary gas is 5 to 50 sccm, preferably, the flow rate of the carbon source is 15 sccm, and the flow rate of the auxiliary gas is 5 sccm; the gas pressure of the in-situ growth is 1 to 15 Pa, preferably, the gas pressure of the in-situ growth is 5 Pa; the time of the in-situ growth is 30 to 300 min, preferably, the time of the in-situ growth is 100 min.

[0046] Specifically, in step S4, an inert gas is introduced to naturally cool down the heating furnace, and the flow rate of the inert gas is 10 sccm. Preferably, the inert gas is N2.

[0047] This embodiment also provides a carbon-based magnetic composite absorbing material, which is prepared using the above-mentioned method for preparing the carbon-based magnetic composite absorbing material.

[0048] This embodiment also provides an application of a carbon-based magnetic composite absorbing material in the field of electromagnetic wave technology. The carbon-based magnetic composite absorbing material is used as an absorbing material or an absorbing agent and has the characteristics of excellent absorbing performance, light weight and thin thickness.

[0049] The present invention adopts PECVD technology to prepare composite wave-absorbing materials, and uses magnetic powder as a matrix to in-situ grow a nano carbon layer. The process flow is simple, and dielectric loss is introduced under the premise of ensuring that the magnetic loss performance of the magnetic matrix remains basically unchanged. On the one hand, the interface contact between the carbon layer and the magnetic micropowder particles is achieved through in-situ compounding between the carbon nano layer and the magnetic powder, and the coupling resonance effect between the two can improve the wave-absorbing performance of the composite material; on the other hand, the growth direction of the surface nano carbon layer can be changed by adjusting the PECVD preparation process parameters, forming a unique three-dimensional topological structure such as a vertical flaky carbon layer, increasing the defects and specific surface area of ​​the carbon layer, which is conducive to further improving the wave-absorbing performance.

[0050] Example 1

[0051] (1) Ni powder is selected as the magnetic matrix. The powder is spherical and has a particle size of 1 to 50 μm.

[0052] (2) The Ni powder is evenly spread on a corundum substrate and placed in a high-temperature tube furnace of a PECVD device.

[0053] (3) Turn on the vacuum pump and evacuate to a vacuum degree of <0.1Pa.

[0054] (4) The heating rate of the high-temperature tube furnace is set to 15°C / min and the growth temperature is set to 700°C for heating.

[0055] (5) When the temperature rises to 700°C, H2 is introduced to pretreat the powder. At the same time, the plasma source is turned on, the H2 flow rate is set to 20 sccm, the RF power is 300 W, and the duration is 20 min.

[0056] (6) CH4 and H2 were introduced into the furnace at the same time, with the flow rates set to 15 sccm and 5 sccm respectively, the RF power was 500 W, the growth pressure was 5 Pa, and the growth time was 100 min.

[0057] (7) Turn off the carbon source and plasma source, and introduce N2 for natural cooling with a flow rate of 10 sccm.

[0058] in, Figure 1 The SEM images of different magnifications of the composite absorber material coated with Ni powder by nano-carbon layer prepared by PECVD in-situ growth method; Figure 2 A comparison chart of the absorbing performance of the nano-carbon layer coated Ni powder absorbing material prepared by the PECVD method and the raw Ni powder. It can be seen from the figure that the maximum absorbing bandwidth of the magnetic absorbing material prepared by the PECVD method is 15.7 GHz, and the minimum reflection loss is -32 dB, while the minimum reflection loss of pure Ni powder is only -5 dB. It can be seen that the nano-carbon layer coated Ni powder absorbing material prepared by the PECVD method of the present invention has excellent absorbing performance.

[0059] Example 2

[0060] (1) FeCo powder is selected as the magnetic matrix. The powder is spherical and has a particle size of 1 to 10 μm.

[0061] (2) The FeCo powder is evenly spread on a corundum substrate and placed in a high-temperature tube furnace of a PECVD device.

[0062] (3) Turn on the vacuum pump and evacuate to a vacuum degree of <0.1Pa.

[0063] (4) A high temperature tube furnace is set with a heating rate of 15°C / min and a growth temperature of 775°C for heating.

[0064] (5) When the temperature rises to 775 °C, H2 is introduced to pretreat the powder. At the same time, the plasma source is turned on, the H2 flow rate is set to 20 sccm, the RF power is 300 W, and the time lasts for 20 min.

[0065] (6) CH4 and H2 were introduced into the high temperature tube furnace at the same time, with the flow rates set to 15 sccm and 5 sccm respectively, the RF power was 500 W, the growth pressure was 5 Pa, and the growth time was 100 min.

[0066] (7) Turn off the carbon source and plasma, and introduce N2 for natural cooling with a flow rate of 10 sccm.

[0067] in, Figure 3 The SEM images of FeCo powder composite absorber coated with nano-carbon layer prepared by PECVD in-situ growth method at different magnifications; Figure 2 This is a comparison chart of the absorbing performance of the nano-carbon layer coated FeCo powder absorbing material prepared by the PECVD method and the raw FeCo powder. It can be seen from the figure that the maximum absorbing bandwidth of the composite absorbing material prepared by the PECVD method is 14.8 GHz, and the minimum reflection loss is -58 dB, while the minimum reflection loss of pure FeCo powder is only -55 dB. It can be seen that the absorbing performance of the nano-carbon layer coated FeCo powder absorbing material prepared by the PECVD method of the present invention is significantly better than that of pure FeCo powder.

[0068] In summary, in the method for preparing a carbon-based magnetic composite absorbing material provided by the present invention, the rapid preparation of the carbon-based magnetic composite absorbing material is achieved through magnetic matrix preparation-pretreatment-PECVD-cooling treatment, and the prepared carbon-based magnetic composite absorbing material has good absorbing performance, and the preparation method is simple in process, strong in operability, high in production efficiency and low in production cost.

[0069] It should be clear that the present invention is not limited to the specific steps and structures described above and shown in the figures. In addition, for the sake of brevity, detailed description of known methods and technologies is omitted here.

[0070] The above is only an embodiment of the present application and is not limited to the present application. For those skilled in the art, the present application may have various changes and variations without departing from the scope of the present invention. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A method for preparing a carbon-based magnetic composite absorbing material, characterized in that: It includes the following steps: S1. Preparation of magnetic matrix: Spread the magnetic matrix on a high temperature resistant substrate, place it in a furnace tube of a heating furnace of a PECVD device, and then evacuate the furnace tube to a vacuum; the magnetic matrix is ​​a high temperature resistant magnetic metal powder, and the particle size of the magnetic matrix is ​​1 to 50 μm; S2, pretreatment: heating the heating furnace to the growth temperature of the magnetic substrate, then introducing H2 to pretreat the magnetic substrate, and simultaneously opening a plasma source to the magnetic substrate to remove the oxide layer on the surface of the magnetic substrate; the growth temperature of the magnetic substrate is 600-900°C; S3, plasma enhanced chemical vapor deposition: a carbon source and an auxiliary gas are introduced into the heating furnace to in-situ grow a nano carbon layer on the magnetic substrate; an interface contact between the carbon layer and the magnetic micro powder particles is achieved through in-situ compounding between the carbon nano layer and the magnetic powder, and good interface bonding force is achieved; S4, cooling treatment: stop introducing the carbon source and turn off the plasma source, then introduce inert gas into the heating furnace to cool it to room temperature to obtain a carbon-based magnetic composite absorbing material.

2. The method for preparing the carbon-based magnetic composite absorbing material according to claim 1, characterized in that: In step S1, the magnetic matrix is ​​Ni powder or FeCo powder.

3. The method for preparing the carbon-based magnetic composite absorbing material according to claim 1, characterized in that: In step S1, the vacuum degree of the vacuum is below 0.1 Pa.

4. The method for preparing the carbon-based magnetic composite absorbing material according to claim 1, characterized in that: In step S2, the heating rate is 10-20°C / min.

5. The method for preparing the carbon-based magnetic composite absorbing material according to claim 1, characterized in that: In step S2, the radio frequency power of the plasma source is 50 to 500 W, the flow rate of H2 is 10 to 40 sccm, the gas pressure in the heating furnace is 1 to 15 Pa, and the pretreatment time is 10 to 30 min.

6. The method for preparing the carbon-based magnetic composite absorbing material according to claim 1, characterized in that: In step S3, the carbon source is CH4, and the auxiliary gas is one or more of H2, N2, and Ar.

7. The method for preparing the carbon-based magnetic composite absorbing material according to claim 1, characterized in that: In step S3, the radio frequency power of the plasma source is 50-500 W, the total flow rate of the carbon source and the auxiliary gas is 5-50 sccm, the gas pressure of the in-situ growth is 1-15 Pa, and the time of the in-situ growth is 30-300 min.

8. A carbon-based magnetic composite absorbing material, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 7.

9. An application of a carbon-based magnetic composite absorbing material, characterized in that: The carbon-based magnetic composite absorbing material according to claim 8 is used as an absorbing material or absorbing agent in the field of electromagnetic wave technology.

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