Flaky feisi al wave-absorbing powder, preparation method and application thereof

Abstract

The application discloses flaky FeSiAl wave-absorbing powder and a preparation method and application thereof, and belongs to the field of wave-absorbing stealth materials and preparation technology thereof. The application solves the technical problems of low-frequency wave band magnetic permeability and incapability of considering dielectric loss performance and magnetic loss performance of existing wave-absorbing materials. The application obtains flaky FeSiAl alloy micro powder by using a ball milling process, obtains flaky FeSiAl wave-absorbing powder by using an annealing process under a reducing atmosphere, and characterizes and analyzes the microstructure of a single particle section of the obtained flaky wave-absorbing powder, obtains the influence and change rule of hydrogen and temperature on the microstructure and micro-area composition, and obtains flaky wave-absorbing powder which can be used for low-frequency band (0.3-2GHz) electromagnetic wave absorption. The wave-absorbing powder has good high-temperature resistance and corrosion resistance, can meet the design requirements of a stealth structure in a harsh environment, and can be used for preparing low-frequency band electromagnetic wave absorption components.

Description

TECHNICAL FIELD

[0001] The present application relates to a flaky FeSiAl wave-absorbing powder and a preparation method and application thereof, and belongs to the field of wave-absorbing stealth materials and preparation technology thereof. BACKGROUND

[0002] The rapid development of radar technology and civil communication technology further puts forward the requirements of "thinner, lighter, wider and stronger" for wave-absorbing materials, especially the rapid changes of new detection and communication technology, which puts forward more stringent performance requirements for electromagnetic absorption of P-L band (P band 0.3~1GHz, L band 1~2GHz). Among them, the long-range early warning radar mainly works in the P band (0.3~1.0 GHz), which has a serious threat to the long-range penetration and battlefield survival of warplanes and warships. The electromagnetic performance of the absorber has a decisive influence on the performance of the wave-absorbing material, and the dielectric constant, magnetic permeability and impedance matching characteristics are the key factors to determine the process of electromagnetic wave entering and loss. These factors are affected by material composition, microstructure, filling rate and distribution characteristics.

[0003] Traditional absorbers are mainly designed for X-band stealth technology and cannot meet the high-efficiency stealth requirements of P-L band; flaky FeSiAl material has a price advantage, and the raw materials are widely available. Due to its high saturation magnetization, high magnetic permeability and low resistivity, it has the potential for high-efficiency absorption of P-band, and is the key material basis for existing P-band stealth technology. However, the optimization process of the electromagnetic performance of flaky FeSiAl wave-absorbing material has not been carried out yet, and high-performance flaky FeSiAl absorber needs to be developed to meet the application requirements of high-efficiency radar stealth in P-band. SUMMARY

[0004] The present application provides a flaky FeSiAl wave-absorbing powder and a preparation method and application thereof, aiming at the problems of low magnetic permeability in low-frequency band, inability to balance dielectric loss performance and magnetic loss performance, and narrow absorption band of existing wave-absorbing materials.

[0005] The technical scheme of the present application is as follows:

[0006] One of the purposes of the present application is to provide a preparation method of flaky FeSiAl wave-absorbing powder, which comprises the following steps:

[0007] Step 1: ball milling treatment of spherical FeSiAl particles to obtain flaky FeSiAl particles;

[0008] Step 2: sieving the flaky FeSiAl particles obtained in step 1 to obtain flaky FeSiAl alloy micro-powder with a thickness of 0.5~1.5μm and a width-thickness ratio of 50~100;

[0009] Step 3: The flaky FeSiAl alloy micro-powder obtained in step 2 is placed in a tube furnace and annealed in a reducing atmosphere to obtain flaky FeSiAl wave-absorbing powder.

[0010] Further limitation, the spherical FeSiAl particle component in step 1 is composed of the following components in terms of mass percentage: 84.5~86.5wt.% of Fe, 9.3~9.9wt.% of Si, and the balance of Al.

[0011] Further limitation, the operation process of step 1 is as follows:

[0012] S1: The spherical FeSiAl particles and grinding balls are mixed in a ball mill jar;

[0013] S2: Anhydrous ethanol is added to the ball mill jar, and then ball milling is performed for 200~280min.

[0014] Further limitation, the grinding balls in S1 are composed of balls with diameters of 20mm, 8mm and 6mm in a mass ratio of (100~150):(100~200):(80~120).

[0015] Further limitation, the mass ratio of grinding balls to spherical FeSiAl particles in S1 is (9~11):1.

[0016] Further limitation, the amount of anhydrous ethanol added in S2 is 0.8~1.2 times the mass of the spherical FeSiAl particles.

[0017] Further limitation, the reducing atmosphere in step 3 is composed of 5vol% H2 and 95vol% Ar.

[0018] Further limitation, the annealing process in step 3 is as follows: heating at a rate of 2.5~5.0℃ / min to 400~900℃ and holding for 2~4h, and then cooling at a rate of 2.5~5.0℃ / min to room temperature.

[0019] The second object of the present application is to provide flaky FeSiAl wave-absorbing powder obtained by the above preparation method.

[0020] The third object of the present application is to provide an application of the above flaky FeSiAl wave-absorbing powder, specifically for preparing low-frequency electromagnetic wave absorbing components. The wave-absorbing component prepared from the wave-absorbing powder annealed at 800℃ has a thickness of 5mm, the minimum value of RL is -30.58dB, and the absorption bandwidth less than -5dB in the test frequency range of 0.3~2GHz reaches 1.64GHz.

[0021] The application obtains flaky FeSiAl alloy micro powder by a ball milling process, and further processes the flaky FeSiAl alloy micro powder obtained by ball milling through an annealing process to obtain flaky FeSiAl wave-absorbing powder which can be used for low-frequency electromagnetic wave absorption.

[0022] (1) The application utilizes a ball milling process to prepare flaky FeSiAl alloy micro powder, and the obtained flaky FeSiAl alloy micro powder has a large residual stress in the interior due to long-time ball milling, and the crystal structure in the interior of the micro powder becomes disordered and chaotic during the ball milling process, so that the grain size is reduced, and a proper annealing process can adjust the order degree of the crystal structure and make the alloy grain grow, and can effectively adjust the magnetic properties of the material.

[0023] (2) The application adjusts the annealing temperature of the annealing process to adjust the crystal structure in the interior of the flaky FeSiAl alloy micro powder and the types of the surface oxide film, and controls the diffusion direction of the Fe element in the interior, and further finely adjusts the electromagnetic parameters, and the flaky FeSiAl alloy micro powder after annealing at different temperatures has a different degree of improvement in the magnetic permeability in the low-frequency wave band, in addition, the oxide film formed after annealing wraps and blocks the eddy current effect caused by magnetic loss, so that the dielectric loss performance and the magnetic loss performance realize good impedance matching, and have important practical application value and broad application prospect in completing low-frequency electromagnetic wave absorption. In addition, the application realizes controllable preparation of the absorber and also realizes adjustment of the electromagnetic performance, and perfects the action mechanism during dielectric / ferromagnetic compounding.

[0024] (3) The flaky FeSiAl wave-absorbing material prepared by the application has good high-temperature resistance and corrosion resistance, can meet the design requirements of stealth structure in harsh environments, and the preparation method has simple steps, good reproducibility, is environment-friendly, has strong controllability, and obtains flaky FeSiAl alloy micro powder with uniform particle size. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 XRD comparison spectrum of flaky FeSiAl alloy micro powder and flaky FeSiAl wave-absorbing powder prepared in different embodiments;

[0026] Figure 2 SEM image of flaky FeSiAl alloy micro powder and flaky FeSiAl wave-absorbing powder prepared in different embodiments;

[0027] Figure 3 Cross-sectional TEM image and element distribution image of flaky FeSiAl alloy micro powder prepared in embodiment 1 and flaky FeSiAl wave-absorbing powder prepared in embodiment 1, embodiment 3 and embodiment 6;

[0028] Figure 4 Electromagnetic wave absorption characteristic images of the flaky FeSiAl alloy micropowder prepared in Example 1 and the flaky FeSiAl wave-absorbing powder prepared in Examples 1-6. DETAILED DESCRIPTION

[0029] In order to make the above objectives, characteristics and advantages of the present application more apparent, the specific embodiments of the present application will be described in detail below with reference to the embodiments of the present application.

[0030] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without the specific details given herein. In other instances, well-known methods have not been described in detail in order to avoid unnecessarily obscuring the present application. Therefore, the present application is not intended to be limited by the specific embodiments disclosed below.

[0031] Secondly, the "one embodiment" or "embodiment" referred to herein means that the specific features, structures or characteristics can be included in at least one implementation of the present application. The "in one embodiment" appearing in different places in the specification does not mean the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments.

[0032] The experimental methods used in the following examples are all conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are all conventional materials, reagents, methods and instruments in the art unless otherwise specified, and can be obtained by commercial channels by those skilled in the art.

[0033] Example 1

[0034] The preparation of the flaky FeSiAl wave-absorbing powder in this embodiment is carried out according to the following steps:

[0035] Step 1: Preparation of flaky FeSiAl particles: 50 g of spherical FeSiAl particles are wet ball-milled in a ball mill at a speed of 450 r / min for 200 min, with anhydrous ethanol as the process control agent added in an amount of 40 g, to obtain flaky FeSiAl particles with a thickness of 1 μm;

[0036] Step 2: The flaky FeSiAl particles are subjected to screening and grading treatment, and the flaky FeSiAl alloy micropowder with a mesh size of 200-300 is taken;

[0037] Step 3: The flaky FeSiAl alloy micropowder obtained in Step 2 is first dried at a temperature of 60℃ for 3 h;

[0038] Step 4: under the condition of reducing gas protection (the reducing gas is composed of 5vol% H2 and 95vol% Ar), the temperature is increased to 400℃ at a rate of 5℃ / min, and the temperature is kept at 400℃ for 2h, and finally cooled to room temperature at a rate of 5℃ / min, to obtain 400℃-flaky FeSiAl wave-absorbing powder, referred to as 400.

[0039] Example 2

[0040] The flaky FeSiAl wave-absorbing powder is prepared according to the following steps:

[0041] Step 1: flaky FeSiAl particle preparation: 50g of spherical FeSiAl particles are wet ball-milled in a ball mill at a rate of 450r / min for 200min, and 40g of anhydrous ethanol is added as a process control agent, to obtain flaky FeSiAl particles with a thickness of 1μm;

[0042] Step 2: the flaky FeSiAl particles are subjected to screening and grading treatment, and the flaky FeSiAl alloy micro-powder with a mesh size of 200~300 is taken;

[0043] Step 3: the flaky FeSiAl alloy micro-powder obtained in step 2 is first dried at a temperature of 60℃ for 3h;

[0044] Step 4: under the condition of reducing gas protection (the reducing gas is composed of 5vol% H2 and 95vol% Ar), the temperature is increased to 500℃ at a rate of 5℃ / min, and the temperature is kept at 500℃ for 2h, and finally cooled to room temperature at a rate of 5℃ / min, to obtain 500℃-flaky FeSiAl wave-absorbing powder, referred to as 500.

[0045] Example 3

[0046] The flaky FeSiAl wave-absorbing powder is prepared according to the following steps:

[0047] Step 1: flaky FeSiAl particle preparation: 50g of spherical FeSiAl particles are wet ball-milled in a ball mill at a rate of 450r / min for 200min, and 40g of anhydrous ethanol is added as a process control agent, to obtain flaky FeSiAl particles with a thickness of 1μm;

[0048] Step 2: the flaky FeSiAl particles are subjected to screening and grading treatment, and the flaky FeSiAl alloy micro-powder with a mesh size of 200~300 is taken;

[0049] Step 3: the flaky FeSiAl alloy micro-powder obtained in step 2 is first dried at a temperature of 60℃ for 3h;

[0050] Step 4: under the condition of reducing gas protection (the reducing gas is composed of 5vol% H2 and 95vol% Ar), the temperature is increased to 600℃ at a rate of 5℃ / min, and the temperature is kept at 600℃ for 2h, and finally cooled to room temperature at a rate of 5℃ / min, to obtain 600℃-flaky FeSiAl wave-absorbing powder, referred to as 600.

[0051] Example 4

[0052] The flaky FeSiAl wave-absorbing powder is prepared according to the following steps:

[0053] Step 1: flaky FeSiAl particle preparation: 50g of spherical FeSiAl particles are wet ball-milled in a ball mill at a rate of 450r / min for 200min, and 40g of anhydrous ethanol is added as a process control agent, to obtain flaky FeSiAl particles with a thickness of 1μm;

[0054] Step 2: the flaky FeSiAl particles are subjected to screening and grading treatment, and the flaky FeSiAl alloy micro-powder with a mesh size of 200~300 is taken;

[0055] Step 3: the flaky FeSiAl alloy micro-powder obtained in step 2 is first dried at a temperature of 60℃ for 3h;

[0056] Step 4: under the condition of reducing gas protection (the reducing gas is composed of 5vol% H2 and 95vol% Ar), the temperature is increased to 700℃ at a rate of 5℃ / min, and the temperature is kept at 700℃ for 2h, and finally cooled to room temperature at a rate of 5℃ / min, to obtain 700℃-flaky FeSiAl wave-absorbing powder, referred to as 700.

[0057] Example 5

[0058] The flaky FeSiAl wave-absorbing powder is prepared according to the following steps:

[0059] Step 1: flaky FeSiAl particle preparation: 50g of spherical FeSiAl particles are wet ball-milled in a ball mill at a rate of 450r / min for 200min, and 40g of anhydrous ethanol is added as a process control agent, to obtain flaky FeSiAl particles with a thickness of 1μm;

[0060] Step 2: the flaky FeSiAl particles are subjected to screening and grading treatment, and the flaky FeSiAl alloy micro-powder with a mesh size of 200~300 is taken;

[0061] Step 3: the flaky FeSiAl alloy micro-powder obtained in step 2 is first dried at a temperature of 60℃ for 3h;

[0062] Step 4: under the condition of reducing gas protection (the reducing gas is composed of 5vol% H2 and 95vol% Ar), the temperature is increased to 800℃ at a rate of 5℃ / min, and the temperature is kept at 800℃ for 2h, and finally cooled to room temperature at a rate of 5℃ / min, to obtain 800℃-flaky FeSiAl wave-absorbing powder, referred to as 800.

[0063] Example 6

[0064] The flaky FeSiAl wave-absorbing powder is prepared according to the following steps:

[0065] Step 1: flaky FeSiAl particle preparation: 50g of spherical FeSiAl particles are wet ball-milled in a ball mill at a rate of 450r / min for 200min, and 40g of anhydrous ethanol is added as a process control agent, to obtain flaky FeSiAl particles with a thickness of 1μm;

[0066] Step 2: the flaky FeSiAl particles are subjected to screening and grading treatment, and the flaky FeSiAl alloy micro-powder with a mesh size of 200~300 is taken;

[0067] Step 3: the flaky FeSiAl alloy micro-powder obtained in step 2 is first dried at a temperature of 60℃ for 3h;

[0068] Step 4: under the condition of reducing gas protection (the reducing gas is composed of 5vol% H2 and 95vol% Ar), the temperature is increased to 900℃ at a rate of 5℃ / min, and the temperature is kept at 900℃ for 2h, and finally cooled to room temperature at a rate of 5℃ / min, to obtain 900℃-flaky FeSiAl wave-absorbing powder, referred to as 900.

[0069] Example 7

[0070] The flaky FeSiAl wave-absorbing powder is prepared according to the following steps:

[0071] Step 1: flaky FeSiAl particle preparation: 50g of spherical FeSiAl particles are wet ball-milled in a ball mill at a rate of 450r / min for 240min, and 50g of anhydrous ethanol is added as a process control agent, to obtain flaky FeSiAl particles with a thickness of 0.8μm;

[0072] Step 2: the flaky FeSiAl particles are subjected to screening and grading treatment, and the flaky FeSiAl alloy micro-powder with a mesh size of 200~300 is taken;

[0073] Step 3: the flaky FeSiAl alloy micro-powder obtained in step 2 is first dried at a temperature of 60℃ for 3h;

[0074] Step 4: under the condition of protection of reducing gas (the reducing gas is composed of 5vol% H2 and 95vol% Ar), the temperature is increased to 400℃ at a rate of 5℃ / min, and the temperature is kept at 400℃ for 3h, and finally cooled to room temperature at a rate of 5℃ / min, to obtain flaky FeSiAl wave-absorbing powder.

[0075] Example 8

[0076] The flaky FeSiAl wave-absorbing powder is prepared according to the following steps:

[0077] Step 1: flaky FeSiAl particle preparation: 50g of spherical FeSiAl particles are wet ball milled in a ball mill at a rate of 450r / min for 240min, and anhydrous ethanol is added as a process control agent in an amount of 50g, to obtain flaky FeSiAl particles with a thickness of 0.8μm;

[0078] Step 2: the flaky FeSiAl particles are subjected to screening and grading treatment, and the flaky FeSiAl alloy micro-powder with a mesh size of 200~300 is taken;

[0079] Step 3: the flaky FeSiAl alloy micro-powder obtained in step 2 is first dried at a temperature of 60℃ for 3h;

[0080] Step 4: under the condition of protection of reducing gas (the reducing gas is composed of 5vol% H2 and 95vol% Ar), the temperature is increased to 500℃ at a rate of 5℃ / min, and the temperature is kept at 500℃ for 3h, and finally cooled to room temperature at a rate of 5℃ / min, to obtain flaky FeSiAl wave-absorbing powder.

[0081] Example 9

[0082] The flaky FeSiAl wave-absorbing powder is prepared according to the following steps:

[0083] Step 1: flaky FeSiAl particle preparation: 50g of spherical FeSiAl particles are wet ball milled in a ball mill at a rate of 450r / min for 240min, and anhydrous ethanol is added as a process control agent in an amount of 50g, to obtain flaky FeSiAl particles with a thickness of 0.8μm;

[0084] Step 2: the flaky FeSiAl particles are subjected to screening and grading treatment, and the flaky FeSiAl alloy micro-powder with a mesh size of 200~300 is taken;

[0085] Step 3: the flaky FeSiAl alloy micro-powder obtained in step 2 is first dried at a temperature of 60℃ for 3h;

[0086] Step 4: under the condition of reducing gas protection (the reducing gas is composed of 5vol% H2 and 95vol% Ar), the temperature is increased to 600℃ at a rate of 5℃ / min, and the temperature is kept at 600℃ for 3h, and finally cooled to room temperature at a rate of 5℃ / min, to obtain flaky FeSiAl wave-absorbing powder.

[0087] Example 10

[0088] The flaky FeSiAl wave-absorbing powder is prepared according to the following steps:

[0089] Step 1: flaky FeSiAl particle preparation: 50g of spherical FeSiAl particles are wet ball milled in a ball mill at a rate of 450r / min for 240min, and 50g of anhydrous ethanol is added as a process control agent, to obtain flaky FeSiAl particles with a thickness of 0.8μm;

[0090] Step 2: the flaky FeSiAl particles are subjected to screening and grading treatment, and the flaky FeSiAl alloy micro-powder with a mesh size of 200~300 is taken;

[0091] Step 3: the flaky FeSiAl alloy micro-powder obtained in step 2 is first dried at a temperature of 60℃ for 3h;

[0092] Step 4: under the condition of reducing gas protection (the reducing gas is composed of 5vol% H2 and 95vol% Ar), the temperature is increased to 700℃ at a rate of 5℃ / min, and the temperature is kept at 700℃ for 3h, and finally cooled to room temperature at a rate of 5℃ / min, to obtain flaky FeSiAl wave-absorbing powder.

[0093] Example 11

[0094] The flaky FeSiAl wave-absorbing powder is prepared according to the following steps:

[0095] Step 1: flaky FeSiAl particle preparation: 50g of spherical FeSiAl particles are wet ball milled in a ball mill at a rate of 450r / min for 240min, and 50g of anhydrous ethanol is added as a process control agent, to obtain flaky FeSiAl particles with a thickness of 0.8μm;

[0096] Step 2: the flaky FeSiAl particles are subjected to screening and grading treatment, and the flaky FeSiAl alloy micro-powder with a mesh size of 200~300 is taken;

[0097] Step 3: the flaky FeSiAl alloy micro-powder obtained in step 2 is first dried at a temperature of 60℃ for 3h;

[0098] Step 4: under the condition of reducing gas protection (the reducing gas is composed of 5vol% H2 and 95vol% Ar), the temperature is increased to 800℃ at a rate of 5℃ / min, and the temperature is kept at 800℃ for 3h, and finally cooled to room temperature at a rate of 5℃ / min, to obtain flaky FeSiAl wave-absorbing powder.

[0099] Example 12

[0100] The flaky FeSiAl wave-absorbing powder is prepared according to the following steps:

[0101] Step 1: flaky FeSiAl particle preparation: 50g of spherical FeSiAl particles are wet ball milled in a ball mill at a rate of 450r / min for 240min, and 50g of anhydrous ethanol is added as a process control agent, to obtain flaky FeSiAl particles with a thickness of 0.8μm;

[0102] Step 2: the flaky FeSiAl particles are subjected to screening and grading treatment, and the flaky FeSiAl alloy powder with a mesh size of 200~300 is taken;

[0103] Step 3: the flaky FeSiAl alloy powder obtained in step 2 is first dried at a temperature of 60℃ for 3h;

[0104] Step 4: under the condition of reducing gas protection (the reducing gas is composed of 5vol% H2 and 95vol% Ar), the temperature is increased to 900℃ at a rate of 5℃ / min, and the temperature is kept at 900℃ for 3h, and finally cooled to room temperature at a rate of 5℃ / min, to obtain flaky FeSiAl wave-absorbing powder.

[0105] Figure 1 The XRD images of the flaky FeSiAl alloy powder prepared in Example 1 and the flaky FeSiAl wave-absorbing powder prepared in Examples 1~6 are shown in the following table: Figure 1 It can be seen that the diffraction peak of the flaky FeSiAl alloy powder sample after ball milling has a weak peak intensity and a wide half-height width, and the peaks in the spectrum of the sample after annealing at different temperatures are obviously more sharp. The lattice stress and defects of the sample after annealing gradually eliminate. And after annealing at 500℃ and above, the peaks of DO3 ordered phase (27.1° and 31.4°) appear. The peaks at 45.0°, 65.5° and 83.0° are the peaks of the main phase α-Fe(Si, Al).

[0106] Figure 2SEM images of the flaky FeSiAl alloy micropowder prepared in Example 1 and the flaky FeSiAl wave-absorbing powder prepared in Examples 1-6, wherein (a) is an SEM image of the flaky FeSiAl alloy micropowder prepared in Example 1, and (b)-(g) are SEM images of the flaky FeSiAl wave-absorbing powder prepared in Examples 1-6, respectively, prepared by Figure 2 It can be seen that the microstructure of the powder is not significantly affected before and after annealing, and the wave-absorbing powder after annealing does not significantly agglomerate.

[0107] Figure 3 Cross-sectional TEM images and element distribution images of the flaky FeSiAl alloy micropowder prepared in Example 1 and the flaky FeSiAl wave-absorbing powder prepared in Examples 1, 3 and 6; Figure 3 In (a), it can be seen from the cross-sectional TEM image of the flaky FeSiAl alloy micropowder that there is an 8 nm or so Fe2O3 layer on the original surface. As shown in (b), when the annealing temperature is increased to 400°C in a hydrogen atmosphere, the Fe2O3 on the surface is reduced, and the Al and Si elements in the matrix are oxidized and wrapped on the surface of the particles. Figure 3 In (a), it can be seen from the cross-sectional TEM image of the flaky FeSiAl alloy micropowder that there is an 8 nm or so Fe2O3 layer on the original surface. As shown in (b), when the annealing temperature is increased to 400°C in a hydrogen atmosphere, the Fe2O3 on the surface is reduced, and the Al and Si elements in the matrix are oxidized and wrapped on the surface of the particles. Figure 3 As shown in (c), when the annealing temperature is further increased to 600°C, the thickness of the surface oxide film does not significantly increase, and correspondingly, the original Fe2O3 layer is thinner, and the Al2O3 and SiO2 layers are thicker. Figure 3 As shown in (d), the temperature is high enough at this time, and the outermost Fe2O3 is fully reduced in a hydrogen atmosphere, and the reduced Fe re-enters and diffuses into the matrix, and the surface oxide film at this time is mainly composed of Al2O3 and SiO2. Overall, in a hydrogen atmosphere, as the annealing temperature increases, the thickness of the surface oxide film does not significantly increase, and the main change is the composition of the surface oxide film. That is, the outermost Fe2O3 is reduced and the reduced Fe re-enters the matrix, but a large amount of Al and Si oxides are generated. Overall, the Fe element shows a tendency to be reduced and diffuse into the matrix, while the Si and Al elements show a tendency to be oxidized and diffuse out of the matrix.

[0108] Figure 4These are electromagnetic wave absorption characteristic images of the absorbing components prepared from the flake-like FeSiAl alloy micro powder obtained in Example 1 and the flake-like FeSiAl absorbing powder obtained in Examples 1-6. The preparation method of the absorbing components is as follows: The test components are made using a molding method. To ensure uniform distribution of the prepared flake-like FeSiAl absorbing powder in paraffin wax, the paraffin wax is heated to 70ºC until it is in a molten state. Then, the absorbing powder prepared in each example is mixed with the molten paraffin wax (mass ratio of 8:2) and thoroughly ground. After the paraffin wax solidifies, the mixture is placed in a mold and pressed into shape. The dimensions of the cylindrical coaxial sample used for electromagnetic performance testing are: inner diameter 3.04 mm, outer diameter 7 mm, and sample thickness ranging from 2.5 to 3.5 mm. Based on the obtained electromagnetic parameters, the transmission line theorem can be applied to calculate and evaluate the electromagnetic wave absorption performance of the prepared samples. Figure 4 It can be seen that the absorption peak of the annealed flake FeSiAl absorbing powder shifts significantly to lower frequencies. Except for the 500℃ and 700℃ flake FeSiAl absorbing powders, the samples annealed at other temperatures achieved absorption of less than -5dB across the entire frequency band (0.3~2GHz). Calculations show that when the 800℃ flake FeSiAl absorbing powder has a thickness of 5mm, the minimum RL value is -30.5dB, and the maximum effective absorption bandwidth is 1.64GHz (0.36~2GHz). Higher electromagnetic loss was obtained by controlling the annealing temperature, thus achieving better microwave absorption performance. Annealing in a reducing atmosphere controlled its electromagnetic parameters, enabling the material to achieve excellent electromagnetic wave absorption performance in the low-frequency range.

[0109] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for preparing sheet-like FeSiAl microwave absorbing powder, characterized in that, The method includes: Step 1: Ball milling is performed on spherical FeSiAl particles to obtain flaky FeSiAl particles; The spherical FeSiAl particles are composed of the following components by mass percentage: 84.5~86.5 wt.% Fe, 9.3~9.9 wt.% Si, and the balance being Al; Step 2: The flaky FeSiAl particles obtained in Step 1 are sieved to obtain flaky FeSiAl alloy micro powder with a thickness of 0.5~1.5μm and a width-to-thickness ratio of 50~100. Step 3: Place the flaky FeSiAl alloy micro powder obtained from step 2 into a tube furnace and anneal it under a reducing atmosphere to obtain flaky FeSiAl microwave absorbing powder. The annealing process in step 3 is as follows: the temperature is increased to 400-900℃ at a rate of 2.5-5.0℃ / min and held for 2-4 hours, and then cooled to room temperature at a rate of 2.5-5.0℃ / min. In step 3, the reducing atmosphere consists of 5 vol% H2 and 95 vol% Ar.

2. The method for preparing the sheet-like FeSiAl microwave absorbing powder according to claim 1, characterized in that, The process of step 1 is as follows: S1, spherical FeSiAl particles are mixed with grinding balls in a ball mill jar; S2, add anhydrous ethanol to the ball mill jar, and then ball mill for 200~280 min.

3. The method for preparing sheet-like FeSiAl microwave absorbing powder according to claim 2, characterized in that, The grinding balls in S1 are composed of 20mm, 8mm and 6mm diameter balls in a mass ratio of (100~150):(100~200):(80~120).

4. The method for preparing sheet-like FeSiAl microwave absorbing powder according to claim 2, characterized in that, The mass ratio of grinding balls to spherical FeSiAl particles in S1 is (9~11):

1.

5. The method for preparing sheet-like FeSiAl microwave absorbing powder according to claim 2, characterized in that, The amount of anhydrous ethanol added in S2 is 0.8 to 1.2 times the mass of the spherical FeSiAl particles.

6. An application of the sheet-like FeSiAl microwave absorbing powder prepared by the method of claim 1, characterized in that, Used to prepare low-frequency electromagnetic wave absorbing components.

7. A component for absorbing low-frequency electromagnetic waves, characterized in that, The sheet-like FeSiAl microwave absorbing powder, prepared by any one of claims 1 to 6, has a thickness of 5 mm.

8. The low-frequency electromagnetic wave absorbing component according to claim 7, characterized in that, This absorption component achieves absorption of less than -5dB across the entire frequency band in the 0.3~2GHz low-frequency band.

Images