Preparation and wave-absorbing performance method of rare earth MOF composite FeSi-based soft magnetic alloy

Abstract

The application relates to a preparation method and wave-absorbing performance of a rare earth MOF composite FeSi-based soft magnetic alloy; flaky FeSi-based soft magnetic alloy powder is used as a matrix to grow blocky Ce-MOF, the composite material improves interface polarization and magnetic loss performance, enhances multi-level structure interface scattering and reflection, reduces the conductivity of the material, and optimizes the impedance matching of the composite material; when the content of the prepared material is 10wt% and the coating thickness is 1.5mm, the reflectivity is optimized from -9.51dB to -45.60dB; the preparation method is simple, the surface of the flaky FeSi-based soft magnetic alloy wave-absorbing powder is slightly oxidized, the erosion of the FeSi-based soft magnetic alloy matrix can be avoided in the Ce-MOF compounding process, the existence of the oxidation layer improves the stability and corrosion resistance of the material; the introduced rare earth Ce can not only adjust the electromagnetic performance of the material, but also participate in adjusting the crystal structure of the MOF, increases the lattice distortion and defects.

Description

Technical Field

[0001] This invention relates to the technical field of magnetic absorbing materials, specifically to a method for preparing and demonstrating the absorbing properties of a rare-earth MOF composite FeSi-based soft magnetic alloy. Background Technology

[0002] With the advent of the 5G era, electronic products have been more widely used in defense, medical, military, and civilian fields. At the same time, this has also brought serious problems such as electromagnetic interference and radiation pollution. It has been reported that long-term exposure to electromagnetic waves can cause calcium loss in people, leading to diseases such as visual impairment and leukemia. In the military field, electromagnetic interference has an adverse effect on the reliability of weapon systems, such as inaccurate intelligence, inability to detect enemy targets, and loss of aircraft control. Therefore, how to prevent electromagnetic interference and solve radiation pollution problems has attracted much attention, and electromagnetic absorbing materials have become a hot topic in current research and development.

[0003] FeSi-based soft magnetic alloys are easy to prepare, inexpensive, and possess good magnetic properties, along with high magnetic loss performance. However, their application is limited by a single loss mechanism. Therefore, researchers introduce dielectric materials to form composite materials with dielectric / magnetic synergistic losses, increasing dielectric loss while optimizing impedance matching performance.

[0004] Metal-organic frameworks (MOFs) are a novel type of microwave absorbing material with advantages such as simple synthesis process, low production cost, good thermal stability, large specific surface area, and high porosity. Furthermore, the derived porous carbon / magnetic metal particle composite materials overcome the problem of uneven magnetic particle dispersion. Compared to main group metal and transition metal MOFs, rare earth MOFs, due to the introduction of rare earth elements, exhibit self-tuning, wide bandwidth, and high efficiency in electromagnetic wave absorbing devices. The introduction of light rare earth element Ce increases the magnetic loss performance of the material, regulates the dielectric-magnetic loss balance, optimizes impedance matching performance, and can also participate in regulating the crystal structure of MOFs, increasing lattice distortion and defects, and improving dielectric loss. This results in composite materials with excellent microwave absorption performance, making them widely applicable in both civilian and military fields. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing rare earth MOF composite FeSi-based soft magnetic alloys and improving their microwave absorption performance. An irregular blocky Ce-MOF is grown and embedded on the surface of the FeSi-based soft magnetic alloy using a hydrothermal method. This structure improves the dielectric-magnetic loss of the material and optimizes the impedance matching of the material, thereby significantly enhancing the microwave absorption performance of the material.

[0006] This invention relates to a method for preparing and demonstrating the microwave absorption properties of a rare-earth MOF composite FeSi-based soft magnetic alloy. The FeSi-based soft magnetic alloy composite magnetic absorbing material uses sheet-like FeSi-based soft magnetic alloy powder as a matrix, and introduces a low-dielectric-constant Ce-MOF onto its surface. The unit molecular formula of the Ce-MOF is C0. 30 H 15 NO3Ce3O 25 .

[0007] Furthermore, in the above technical solution, the mass ratio of the matrix to Ce-MOF is 60-90wt%: 40-10wt%.

[0008] Furthermore, in the above technical solution, the FeSi-based soft magnetic alloy powder is a high-permeability sheet-like FeSiCr or FeSiAl.

[0009] Furthermore, in the above technical solution, when the matrix is ​​FeSiCr, the mass percentages of Fe, Si and Cr are 86.5wt%, 11.6wt%, and 1.9wt%, respectively.

[0010] A method for preparing and demonstrating the microwave absorption properties of a rare-earth MOF composite FeSi-based soft magnetic alloy includes the following steps: Step S1: Ball mill the micron-sized gas-atomized FeSi-based magnetic powder at a speed of 2500-3000 rpm for 12-36 hours to obtain sheet-like FeSi-based soft magnetic alloy powder. Step S2: The sheet-like FeSi-based soft magnetic alloy powder prepared in step S1 is heated from room temperature to 200-500℃ at a heating rate of 2-5℃ / min under an oxygen atmosphere and calcined for 2-6 hours, and then cooled to room temperature to obtain a matrix. The matrix is ​​a sheet-like FeSi-based soft magnetic alloy microwave absorbing powder with micro-oxidation on the surface. Step S3: The sheet-like FeSi-based soft magnetic alloy microwave absorbing powder obtained in step S2, cerium nitrate hexahydrate (Ce(NO3)3∙6H2O), and pyromellitic acid (PMA) are sequentially dissolved in N,N-dimethylformamide (DMF). After mechanical stirring, a hydrothermal reaction is carried out. After the hydrothermal reaction is completed, the mixture is cooled, filtered, washed, dried, and ground to obtain a composite magnetic microwave absorbing material in which rare earth metal-organic framework (Ce-MOF) is grown on the surface of FeSi-based soft magnetic alloy. Furthermore, in the above technical solution, in step S3, the hydrothermal reaction is carried out under the condition of heating at 130°C for 24 hours; Furthermore, in the above technical solution, the mechanical stirring time in step S3 is 40 mins; Furthermore, in the above technical solution, in step S2, the heating rate is 5℃ / min, the temperature is 400℃, and the holding time is 4hrs; Furthermore, in the above technical solution, in step S1, the rotation speed is 2800 rpm and the ball milling time is 28 hours.

[0011] The beneficial effects of the embodiments of the present invention are as follows: The present invention possesses the high permeability performance of FeSi-based soft magnetic alloys, comprehensively considers multiple factors to improve the microwave absorption performance of the material; and because of the introduction of rare earth elements, the dielectric-magnetic loss balance is adjusted, the impedance matching performance is optimized, and multiple reflection / scattering effects are increased. At the same time, it can also participate in adjusting the crystal structure of MOF, increasing lattice distortion and defects, thereby achieving the purpose of improving the microwave absorption performance of composite materials. Attached Figure Description

[0012] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is an X-ray diffraction pattern of the FeSiCr soft magnetic alloy and Ce-MOF composite FeSiCr soft magnetic alloy microwave absorbing material in this invention.

[0014] Figure 2 This is a SEM image of the Ce-MOF composite FeSiCr soft magnetic alloy microwave absorbing material in this invention.

[0015] Figure 3 This is a comparison diagram of the reflection loss of the FeSiCr soft magnetic alloy absorbing material in this invention before and after Ce-MOF growth on its surface. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art without creative effort to obtain all other embodiments should be included within the protection scope of the present invention.

[0017] Unless otherwise specified, all experimental methods used in the following examples are conventional methods; and all materials and reagents used in the following examples are commercially available unless otherwise specified.

[0018] Example 1: This example contains Ce 3+ The ion used has the molecular formula (Ce(NO3)3∙6H2O); it includes a composite magnetic absorbing material in which a rare earth metal-organic framework (Ce-MOF) is grown on the surface of a FeSiCr soft magnetic alloy; the matrix of the above material is 95wt% FeSiCr and the surface contains 5wt% Ce-MOF; the mass percentages of Fe, Si and Cr are 86.5wt%, 11.6wt% and 1.9wt%, respectively.

[0019] This embodiment also includes a method for preparing a composite magnetic absorbing material in which rare earth metal-organic frameworks (Ce-MOFs) are grown on the surface of FeSi soft magnetic alloys, comprising the following steps: Step S1: Ball mill the micron-sized gas-atomized FeSi-based magnetic powder at a speed of 2800 rpm for 28 hours to obtain sheet-like FeSi-based soft magnetic alloy powder. Step S2: Place the sheet-like FeSiCr soft magnetic alloy powder obtained in step S1 into a quartz tube and evacuate it in a tube furnace. Then fill it with oxygen until the gas pressure inside the quartz tube reaches atmospheric pressure. Then, keep the oxygen flowing into the quartz tube at a flow rate of 0.2 L / min. Then, raise the temperature from room temperature to 400℃ at a heating rate of 5℃ / min and calcine for 4 hours. Then, let it cool naturally to room temperature to obtain the matrix. The above matrix is ​​sheet-like FeSiCr soft magnetic alloy microwave absorbing powder with micro-oxidation on the surface. Step S3: Hydrothermal Coating: Take 0.8g of FeSiCr soft magnetic alloy powder microwave absorbing material obtained in Step S2, 0.15g of lanthanum ferric chloride hexahydrate (CeCl3·6H2O) and 0.05g of pyromellitic acid (PMA) and dissolve them in 40ml of N,N-dimethylformamide (DMF). Then, mechanically stir at 350r / min for 40min and transfer the mixture to a stainless steel reactor lined with polytetrafluoroethylene. Then, place the reactor in a constant temperature drying oven and heat at 130℃ for 24hrs. After the reactor cools to room temperature, the reaction product is centrifuged and washed three times with DMF. It is then dried in a vacuum drying oven at 60℃ for 12hrs and ground to obtain a composite magnetic microwave absorbing material with rare earth metal-organic framework (Ce-MOF) grown on the surface of FeSiCr soft magnetic alloy.

[0020] Example 2: This example contains Ce 3+The ion used has the molecular formula (Ce(NO3)3∙6H2O); it includes a composite magnetic absorbing material in which a rare earth metal-organic framework (Ce-MOF) is grown on the surface of a FeSiCr soft magnetic alloy; the matrix of the above material is 90wt% FeSiCr and the surface contains 10wt% Ce-MOF; the mass percentages of Fe, Si and Cr are 86.5wt%, 11.6wt% and 1.9wt%, respectively.

[0021] This embodiment also includes a method for preparing a composite magnetic absorbing material with a rare earth metal-organic framework Ce-MOF grown on the surface of a FeSi soft magnetic alloy, comprising the following steps: Step S1: Ball mill the micron-sized gas-atomized FeSi-based magnetic powder at a speed of 2800 rpm for 28 hours to obtain sheet-like FeSi-based soft magnetic alloy powder. Step S2: The sheet-like FeSiCr soft magnetic alloy powder obtained in step S1 is placed in a quartz tube and a vacuum is drawn in a tube furnace. Oxygen is then introduced until the gas pressure inside the quartz tube reaches atmospheric pressure. Oxygen is then introduced into the quartz tube at a flow rate of 0.2 L / min. The temperature is then increased from room temperature to 400℃ at a heating rate of 5℃ / min and calcined for 4 hours. After that, it is naturally cooled to room temperature to obtain the matrix. The matrix is ​​a sheet-like FeSiCr soft magnetic alloy microwave absorbing powder with a slightly oxidized surface. Step S3: Hydrothermal Coating: Take 0.8g of FeSiCr soft magnetic alloy powder microwave absorbing material obtained in Step S2, 0.2g of cerium nitrate hexahydrate (Ce(NO3)3∙6H2O) and 0.1g of pyromellitic acid (PMA), dissolve them in 40ml of N,N-dimethylformamide (DMF), and then mechanically stir at 350r / min for 40min. Then transfer it to a stainless steel reactor lined with polytetrafluoroethylene, and place it in a constant temperature drying oven at 130℃ for 24hrs. After the reactor cools to room temperature, the reaction product is separated by centrifugation and washed three times with DMF. It is then dried in a vacuum drying oven at 60℃ for 12hrs and ground to obtain a composite magnetic microwave absorbing material with rare earth metal-organic framework Ce-MOF grown on the surface of FeSiCr soft magnetic alloy.

[0022] Example 3: This example contains Ce 3+ The ion used has the molecular formula (Ce(NO3)3∙6H2O); it includes a composite magnetic absorbing material in which a rare earth metal-organic framework Ce-MOF is grown on the surface of a FeSiCr soft magnetic alloy; the matrix of the above material is 85wt% FeSiCr and the surface contains 15wt% Ce-MOF; the mass percentages of Fe, Si and Cr are 86.5wt%, 11.6wt% and 1.9wt%, respectively.

[0023] This embodiment also includes a method for preparing a composite magnetic absorbing material with a rare earth metal-organic framework Ce-MOF grown on the surface of a FeSi soft magnetic alloy, comprising the following steps: Step S1: Ball mill the micron-sized gas-atomized FeSi-based magnetic powder at a speed of 2800 rpm for 28 hours to obtain sheet-like FeSi-based soft magnetic alloy powder. Step S2: The sheet-like FeSiCr soft magnetic alloy powder obtained in step S1 is placed in a quartz tube and a vacuum is drawn in a tube furnace. Oxygen is then introduced until the gas pressure inside the quartz tube reaches atmospheric pressure. Oxygen is then introduced into the quartz tube at a flow rate of 0.2 L / min. The temperature is then increased from room temperature to 400℃ at a heating rate of 5℃ / min and calcined for 4 hours. After that, it is naturally cooled to room temperature to obtain the matrix. The matrix is ​​a sheet-like FeSiCr soft magnetic alloy microwave absorbing powder with a slightly oxidized surface. Step S3: Hydrothermal Coating: Take 0.8g of FeSiCr soft magnetic alloy powder microwave absorbing material obtained in Step S2, 0.25g of cerium nitrate hexahydrate (Ce(NO3)3∙6H2O) and 0.15g of pyromellitic acid (PMA) and dissolve them in 40ml of N,N-dimethylformamide (DMF). Then, mechanically stir at 350r / min for 40min and transfer the mixture to a stainless steel reactor lined with polytetrafluoroethylene. Then, place the reactor in a constant temperature drying oven and heat at 130℃ for 24hrs. After the reactor cools to room temperature, the reaction product is centrifuged and washed three times with DMF. It is then dried in a vacuum drying oven at 60℃ for 12hrs and ground to obtain a composite magnetic microwave absorbing material with rare earth metal-organic framework (Ce-MOF) grown on the surface of FeSiCr soft magnetic alloy.

[0024] Example 4: This example contains Ce 3+ The ion used has the molecular formula (Ce(NO3)3∙6H2O); it includes a composite magnetic absorbing material in which a rare earth metal-organic framework (Ce-MOF) is grown on the surface of a FeSiAl soft magnetic alloy; the matrix of the above material is 95wt% FeSiCr and the surface contains 5wt% Ce-MOF; the mass percentages of Fe, Si and Al are 87.2wt%, 9.5wt%, and 3.3wt%, respectively.

[0025] A method for preparing a composite magnetic microwave absorbing material with rare earth metal-organic frameworks (Ce-MOF) grown on the surface of FeSiAl soft magnetic alloy includes the following steps: The difference between Example 4 and Example 1 is that FeSiCr in steps S1, S2 and S3 is replaced with FeSiAl, and the mass percentage of FeSiAl soft magnetic alloy is 87.2 wt%, Si is 9.5 wt% and Al is 3.3 wt%. All other steps are the same as in Example 1.

[0026] Example 5: This example contains Ce 3+ The ion used has the molecular formula (Ce(NO3)3∙6H2O); it includes a composite magnetic absorbing material in which a rare earth metal-organic framework (Ce-MOF) is grown on the surface of a FeSiAl soft magnetic alloy; the matrix of the above material is 90wt% FeSiAl and the surface contains 10wt% Ce-MOF; the mass percentages of Fe, Si and Al are 87.2wt%, 9.5wt% and 3.3wt%, respectively.

[0027] A method for preparing a composite magnetic microwave absorbing material with rare earth metal-organic frameworks (Ce-MOF) grown on the surface of FeSiAl soft magnetic alloy includes the following steps: The difference between Example 5 and Example 2 is that FeSiCr in steps S1, S2 and S3 is replaced with FeSiAl, and the mass percentage of FeSiAl soft magnetic alloy is 87.2 wt%, Si is 9.5 wt% and Al is 3.3 wt%. All other steps are the same as in Example 2.

[0028] Example 6: This example contains Ce 3+ The ion used has the molecular formula (Ce(NO3)3∙6H2O); it includes a composite magnetic absorbing material in which a rare earth metal-organic framework (Ce-MOF) is grown on the surface of a FeSiAl soft magnetic alloy; the matrix of the above material is 85wt% FeSiAl and the surface contains 15wt% Ce-MOF; the mass percentages of Fe, Si and Al are 87.2wt%, 9.5wt% and 3.3wt%, respectively.

[0029] A method for preparing a composite magnetic microwave absorbing material with rare earth metal-organic frameworks (Ce-MOF) grown on the surface of FeSiAl soft magnetic alloy includes the following steps: The difference between Example 6 and Example 3 is that FeSiCr in steps S1, S2 and S3 is replaced with FeSiAl, and the mass percentage of FeSiAl soft magnetic alloy is 87.2 wt%, Si is 9.5 wt% and Al is 3.3 wt%. All other steps are the same as in Example 3.

[0030] Supplementary Example 1: This embodiment contains Eu 3+The molecular formula of the reagent used for the ion is (Eu(NO3)3·6H2O); this example includes a composite magnetic absorbing material of Ce-MOF grown on the surface of FeSiCr / Al soft magnetic alloy; its preparation method is the same as that of Examples 1-6, except that Eu(NO3)3·6H2O is replaced with Eu(NO3)3·6H2O in step S3; the remaining steps and experimental conditions are the same.

[0031] Supplementary Example 2: This embodiment contains La 3+ The molecular formula of the reagent unit used for the ion is (La(NO3)3·6H2O); this example includes a composite magnetic absorbing material of La-MOF grown on the surface of FeSiCr / Al soft magnetic alloy; its preparation method is the same as that of Examples 1-6, except that Ce(NO3)3·6H2O is replaced with La(NO3)3·6H2O in step S3; the remaining steps and experimental conditions are the same.

[0032] Experimental Example 1: This experimental example describes the characterization of materials from each step of Example 1. A PANalytical-Empyrean X-ray diffractometer was used to characterize the phase composition of the composite magnetic absorbing material obtained in step S3 of Example 1, where the rare-earth metal-organic framework (Ce-MOF) is grown on the surface of a FeSiAl soft magnetic alloy. The results are as follows: Figure 1 As shown.

[0033] The electromagnetic parameters of the material were tested and the reflectivity was calculated using a 3672B-SCETC vector network analyzer. The sheet-like FeSiCr magnetic absorbing powder prepared in step S2 of Example 1, and the composite magnetic absorbing material with a rare-earth metal-organic framework (Ce-MOF) grown on the surface of a FeSiCr soft magnetic alloy prepared in step S3 of Example 1, were mixed with paraffin wax at a mass ratio of 3:1 to prepare coaxial samples with outer and inner diameters of 7 mm and 3 mm respectively, and a thickness of approximately 2 mm. The complex permeability and complex permittivity of the samples in the 2-18 GHz frequency band were measured. The reflectivity R of the single-layer absorbing material was calculated and simulated using the following formula. The results are as follows: Figure 3 As shown.

[0034]

[0035] In equation (1), εr, μr and d These represent the complex permittivity, complex permeability, and thickness of the absorbing material, respectively. f The frequency of electromagnetic waves, c The speed at which electromagnetic waves propagate in a vacuum. j It is the imaginary unit.

[0036] from Figure 1It can be seen that the composite magnetic absorbing material with rare earth metal-organic framework (Ce-MOF) synthesized in Example 1 grown on the surface of FeSiCr soft magnetic alloy has FeSiCr and Ce-MOF as its main phase composition; from Figure 3 As can be seen, after Ce-MOF growth, the reflectivity of the composite magnetic absorbing material with rare earth metal-organic framework (MOF) grown on the surface of FeSi-based soft magnetic alloy is optimized from -9.51dB to -45.60dB when the Ce-MOF content is 10wt% and the coating thickness is 1.5mm. This shows that the absorption performance of the composite magnetic absorbing material with rare earth metal-organic framework (Ce-MOF) grown on the surface of FeSi-based soft magnetic alloy is significantly improved. This indicates that the composite magnetic absorbing material with rare earth metal-organic framework (Ce-MOF) grown on the surface of FeSi-based soft magnetic alloy prepared in this invention can achieve effective absorption of electromagnetic waves at a low thickness.

[0037] In summary, this invention introduces the rare earth element Ce and employs a hydrothermal method to in-situ grow a rare earth metal-organic framework (Ce-MOF) on the surface of a FeSi-based soft magnetic alloy, constructing a Ce-MOF / FeSi-based composite magnetic absorbing material. While maintaining the excellent soft magnetic properties of the FeSi-based soft magnetic alloy, this material achieves a stable oxide layer on the metal powder surface through micro-oxidation heat treatment, resulting in a sheet-like FeSi-based magnetic absorbing powder with a micro-oxidized surface. This makes it less susceptible to corrosion during subsequent hydrothermal reactions and facilitates the growth of MOF crystals on its surface. The introduction of Ce enhances the material's polarization response and modulates the synergistic effect between dielectric and magnetic losses, thereby optimizing the material's impedance matching characteristics. Simultaneously, Ce participates in the construction of the MOF crystal structure, inducing lattice distortion and structural defects, further improving the microwave absorption performance of the composite material. This method is simple, and the resulting material exhibits good chemical stability and promising application prospects.

Claims

1. A method for preparing and demonstrating the microwave absorption properties of a rare-earth MOF composite FeSi-based soft magnetic alloy, characterized in that: The FeSi-based soft magnetic alloy composite magnetic absorbing material uses sheet-like FeSi-based soft magnetic alloy powder as a matrix, and introduces low-dielectric-constant Ce-MOF on its surface. The unit molecular formula of the Ce-MOF is C. 30 H 15 NO3Ce3O 25 .

2. The composite magnetic absorbing material of Ce-MOF grown on the surface of FeSi-based soft magnetic alloy as described in claim 1, characterized in that: The mass ratio of the matrix to the Ce-MOF is 60-90wt%: 60-10wt%.

3. The method for preparing and measuring the microwave absorption properties of the rare-earth MOF composite FeSi-based soft magnetic alloy as described in claim 2, characterized in that: The FeSi-based soft magnetic alloy magnetic powder is a high-permeability sheet-like FeSiCr or FeSiAl.

4. The method for preparing and measuring the microwave absorption properties of the rare-earth MOF composite FeSi-based soft magnetic alloy as described in claim 3, characterized in that: When the matrix is ​​FeSiCr, the mass percentages of Fe, Si and Cr are 86.5wt%, 11.6wt% and 1.9wt%, respectively.

5. The method for preparing and demonstrating the microwave absorption properties of the rare-earth MOF composite FeSi-based soft magnetic alloy as described in claims 2-4, comprising the following steps: Step S1: Ball mill the micron-sized gas-atomized FeSi-based magnetic powder at a speed of 2500-3000 rpm for 12-36 hours to obtain sheet-like FeSi-based soft magnetic alloy powder. Step S2: The sheet-like FeSi-based soft magnetic alloy powder prepared in step S1 is heated from room temperature to 200-500℃ at a heating rate of 2-5℃ / min under an oxygen atmosphere and calcined for 2-6 hours, and then cooled to room temperature to obtain a matrix. The matrix is ​​a sheet-like FeSi-based soft magnetic alloy microwave absorbing powder with micro-oxidation on the surface. Step S3: The sheet-like FeSi-based soft magnetic alloy absorbing powder obtained in step S2, cerium nitrate hexahydrate (Ce(NO3)3∙6H2O), and pyromellitic acid (PMA) are dissolved sequentially in N,N-dimethylformamide (DMF). After mechanical stirring, a hydrothermal reaction is carried out. After the hydrothermal reaction is completed, the mixture is cooled, filtered, washed, dried, and ground to obtain a composite magnetic absorbing material with a rare earth metal-organic framework (Ce-MOF) grown on the surface of the FeSi-based soft magnetic alloy.

6. The method for preparing and measuring the microwave absorption properties of the rare-earth MOF composite FeSi-based soft magnetic alloy as described in claim 5, characterized in that: In step S3, the hydrothermal reaction is carried out under the condition of heating at 110-180℃ for 12-36 hours.

7. The method for preparing and measuring the microwave absorption properties of the rare-earth MOF composite FeSi-based soft magnetic alloy as described in claim 5, characterized in that: In step S3, the mechanical stirring time is 40 mins.

8. The method for preparing and measuring the microwave absorption properties of the rare-earth MOF composite FeSi-based soft magnetic alloy as described in claim 5, characterized in that: In step S2, the oxidation heating rate is 5℃ / min, the oxidation temperature is 400℃, and the holding time is 4hrs.

9. The method for preparing and measuring the microwave absorption properties of the rare-earth MOF composite FeSi-based soft magnetic alloy as described in claim 5, characterized in that: In step S1, the rotation speed is 2800 rpm and the ball milling time is 28 hours.

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