Preparation method of flaky wave-absorbing soft magnetic composite material and product of flaky wave-absorbing soft magnetic composite material

Abstract

The invention discloses a preparation method of a flaky wave-absorbing soft magnetic composite material and a product thereof. The preparation method comprises the following steps: crushing an iron-silicon-aluminum alloy, and carrying out ball milling to obtain flaky iron-silicon-aluminum powder; and carrying out controllable oxygen partial pressure high-temperature heat treatment on the obtained flaky Fe-Si-Al powder in an inert atmosphere containing 1-3% of oxygen by volume at the temperature of more than 650 DEG C to obtain the flaky wave-absorbing soft magnetic composite material. According to the invention, the uniform composite oxide layer of silicon dioxide and aluminum oxide is formed on the Fe-Si-Al surface by controlling atmosphere oxidation, and the oxide layer realizes higher electromagnetic wave absorption performance by improving impedance matching and shows stronger corrosion resistance. The preparation method is suitable for large-scale industrial production.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electromagnetic wave absorbing materials, and particularly relates to a preparation method of a flaky wave-absorbing soft magnetic composite material and a product thereof. BACKGROUND

[0002] With the extension of modern military equipment to harsh environments such as oceans and polar regions, and the increasing demand for long-term stable operation of 5G communication infrastructure, it is urgent to develop new wave-absorbing materials with excellent wave-absorbing properties and strong environmental adaptability. In recent years, corrosion-resistant wave-absorbing materials have become an important research focus in the field of electromagnetic functional materials. The core goal is to break through the technical bottleneck of performance degradation of traditional wave-absorbing materials in extreme environmental conditions.

[0003] Iron-silicon-aluminum alloys, with the synergistic effect between silicon and aluminum elements, can spontaneously form a dense passivation layer on the surface, thereby significantly enhancing their resistance to salt spray corrosion and damp heat aging, while maintaining high magnetic loss capability. Current research focuses on key technical paths such as multi-element alloy design, nano-composite structure construction, and surface engineering modification, aiming to achieve the synergistic optimization of wideband absorption performance and multi-scenario environmental tolerance.

[0004] Such materials have shown irreplaceable advantages in military and civilian application scenarios such as ship stealth protection coatings, airborne radar radomes, and coastal communication base stations, and their research and development progress is directly related to the reliability and service life of high-end equipment in complex environments.

[0005] However, iron-silicon-aluminum alloys are prone to corrosion in extreme humid and smoky environments, which can damage the alloy surface and affect its wave-absorbing performance. To improve its corrosion resistance and wave-absorbing performance, current methods mainly involve atomic layer deposition technology (ALD) and chemical oxidation method to coat an oxide shell layer on the surface of the iron-silicon-aluminum alloy. Although atomic layer deposition technology can control the thickness and structure of the coated oxide film, it is still cumbersome and difficult to apply in large-scale industrial production. While the chemical oxidation method is simple, it is difficult to control the composition of the coated oxide layer. To solve this problem, the present application prepares a flaky wave-absorbing soft magnetic composite material and generates a composite coating of silicon oxide and aluminum oxide on the surface through controllable oxygen partial pressure heat treatment, thereby obtaining a wave-absorbing material with a core-shell structure. The magnetic composite corrosion-resistant wave-absorbing material has good reflection loss and large absorption bandwidth, as well as good corrosion resistance. SUMMARY

[0006] The purpose of the present application aims to respond to the current environmental demand for high-performance electromagnetic wave absorbing materials, and proposes a preparation method of flaky wave-absorbing soft magnetic composite material and its product. The method adopts mechanical ball milling combined with atmosphere oxidation process, fully integrates the magnetic performance advantages and crystal structure characteristics of the material itself, and finally obtains flaky electromagnetic wave absorbing material with excellent corrosion resistance, solving the defects of complex preparation process, limited absorption frequency band width and performance degradation of wave-absorbing materials in practical application at present stage.

[0007] To achieve the purpose of the present application, the present application adopts the following technical solutions: In the first aspect, the present application provides a preparation method of flaky wave-absorbing soft magnetic composite material, comprising: The iron-silicon-aluminum alloy is broken and ball milled to obtain flaky iron-silicon-aluminum powder; the obtained flaky iron-silicon-aluminum powder is subjected to controllable oxygen partial pressure high-temperature heat treatment in an inert atmosphere containing oxygen with a volume fraction of 1-3 % and at a temperature greater than 650 DEG C to obtain a flaky wave-absorbing soft magnetic composite material; the flaky wave-absorbing soft magnetic composite material has a core-shell structure, with flaky iron-silicon-aluminum particles as the core and a composite oxide layer composed of silicon oxide and aluminum oxide as the shell.

[0008] Preferably, the mass ratio of iron, silicon and aluminum in the iron-silicon-aluminum alloy is 85:(9.0-10.2):(4.8-6.0).

[0009] Preferably, the ball milling conditions are to use anhydrous ethanol as the medium, the ball-to-material ratio is 20:1, and the ball milling time is 48-60 h. Preferably, the thickness of the flaky iron-silicon-aluminum powder after ball milling is 1.5-2 μm, and the diameter-to-thickness ratio is 9.5-11.5.

[0010] Preferably, the inert gas in the inert atmosphere is argon.

[0011] Preferably, the controllable oxygen partial pressure high-temperature heat treatment temperature is 650-850 DEG C, and the time is 20-30 min.

[0012] Preferably, the preparation of the iron-silicon-aluminum alloy is to obtain an alloy ingot by induction melting of pure iron, pure silicon and pure aluminum alloy raw materials; and the obtained alloy ingot is subjected to ribbon drawing to obtain an iron-silicon-aluminum alloy strip.

[0013] More preferably, the induction melting atmosphere in the preparation of the iron-silicon-aluminum alloy is high-purity argon, and the pressure is 0.06-0.08 MPa.

[0014] More preferably, the alloy ingot ribbon drawing speed is 35-45 m / s; the width of the iron-silicon-aluminum strip is 1-1.5 mm, and the thickness is 20-30 μm.

[0015] In a second aspect, the present application provides a flaky wave-absorbing soft magnetic composite material prepared by the above method.

[0016] The present application has at least the following advantages: (1) The flaky iron-silicon-aluminum powder is used in the present application, and the thickness d of the obtained flaky iron-silicon-aluminum powder reaches 1.5 μm after ball milling for more than 48 h, and the diameter-thickness ratio is 11.5, which makes the thickness closer to the skin depth of iron-silicon-aluminum, so that the electromagnetic wave can be fully absorbed inside the material. Compared with the traditional spherical iron-silicon-aluminum powder, the flaky iron-silicon-aluminum has a larger specific surface area, and can promote the absorption and dissipation of electromagnetic waves through more interface scattering and conductive network, thereby improving the wave-absorbing performance.

[0017] (2) The present application forms an oxide film layer on the surface of the flaky iron-silicon-aluminum powder by controlling the oxygen partial pressure. The composite oxide film layer formed in the controllable atmosphere is more uniform, and the composition of the oxide film can be adjusted by controlling the heat treatment parameters. This process operation procedure is simple, environmentally friendly, and more suitable for large-scale industrial production. At the same time, the composite oxide film layer is dense and uniform, which effectively blocks the penetration of corrosive media such as moisture and salt mist as a passivation layer. It has stronger environmental adaptability while maintaining high wave-absorbing performance, and is especially suitable for military and civilian applications in corrosive environments such as oceans and hot and humid environments. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The XRD curve image of the flaky wave-absorbing soft magnetic composite material prepared in Examples 1-3.

[0019] Figure 2 The microstructure electron microscope image of the flaky iron-silicon-aluminum powder obtained after ball milling in Example 3 at 1500 times.

[0020] Figure 3 The microstructure electron microscope image of the flaky wave-absorbing soft magnetic composite material in Example 3 at 2000 times. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0022] At least one embodiment provides a preparation method of a flaky wave-absorbing soft magnetic composite material, which comprises: The iron-silicon-aluminum alloy is crushed and ball milled to obtain flaky iron-silicon-aluminum powder; the obtained flaky iron-silicon-aluminum powder is subjected to high-temperature heat treatment with controllable oxygen partial pressure in an inert atmosphere containing oxygen with a volume fraction of 1-3% and at a temperature greater than 650°C to obtain a flaky wave-absorbing soft magnetic composite material; the flaky wave-absorbing soft magnetic composite material has a core-shell structure, with the flaky iron-silicon-aluminum particles as the core and a composite oxide layer composed of silicon oxide and aluminum oxide as the shell.

[0023] In some embodiments, the mass ratio of iron, silicon and aluminum in the iron-silicon-aluminum alloy is 85:(9.0-10.2):(4.8-6.0).

[0024] In some embodiments, the crushing of the iron-silicon-aluminum alloy can be mechanically crushed using a high-energy pulverizer to convert it into primary powder particles.

[0025] In some embodiments, the ball milling conditions are that anhydrous ethanol is used as the medium, filled to about 50% of the volume of the tank, the ball-to-material ratio is 20:1, and the ball milling time is 48-60 h. Preferably, after the ball milling is completed, the ball milling tank is transferred to a vacuum drying box for low-temperature drying to obtain flaky iron-silicon-aluminum powder. The ball milling process of the present application uses anhydrous ethanol as the medium, and the ball milling process is controlled to ensure that the powder morphology is controllable; the heat treatment process is adjusted by adjusting the oxygen partial pressure, temperature and time to achieve precise control of the composition and thickness of the oxide layer.

[0026] In some embodiments, the thickness of the flaky iron-silicon-aluminum powder after ball milling is 1.5-2 μm, and the diameter-to-thickness ratio is 9.5-11.5.

[0027] In some embodiments, the inert gas in the inert atmosphere is argon.

[0028] In some embodiments, in the above controllable oxygen partial pressure heat treatment process, the controllable oxygen partial pressure heat treatment temperature of each raw material can be selected according to actual needs, for example: in some embodiments, the oxygen partial pressure concentration is 1-3%, which can be selected from 1%, 2%, 3%; the controllable oxygen partial pressure heat treatment time is 20-30 min, which can be selected from 20 min, 25 min, 30 min; the controllable oxygen partial pressure heat treatment temperature is 650-850°C, which can be selected from 650°C, 700°C, 750°C, 800°C, 850°C; in addition to the above example values, any value within the range can also be used, which is not limited herein.

[0029] In some embodiments, the preparation of the iron-silicon-aluminum alloy is by induction melting of pure iron, pure silicon and pure aluminum alloy raw materials to obtain an alloy ingot; the obtained alloy ingot is subjected to ribbon drawing to obtain iron-silicon-aluminum alloy strip. (1) Induction melting of appropriate proportions of pure iron, pure silicon and pure aluminum alloy raw materials to obtain an alloy ingot.

[0030] Specifically, the iron-based alloy raw materials (i.e., pure iron, pure silicon, and pure aluminum) are weighed according to a preset ratio, put into an induction melting furnace, melted and mixed into a homogeneous alloy liquid, the molten alloy is poured into a copper mold, and cooled in a vacuum environment for 20-30 min, thereby obtaining an alloy ingot with relatively uniform component distribution. For example, the purity of pure iron is 99.5%, the purity of pure silicon is 99.9%, and the purity of pure aluminum is 99.9%.

[0031] In some embodiments, the atmosphere for the preparation of the iron-silicon-aluminum alloy is high-purity argon, and the pressure is 0.06-0.08 MPa.

[0032] For example, step (1) is specifically: The iron-based alloy raw materials are weighed according to a preset ratio, a ceramic crucible is placed in a heating coil, the furnace door is closed, a mechanical pump is used to pre-evacuate the cavity of the induction melting furnace, high-purity argon is used for three times of gas washing, when the vacuum degree reaches below 10 Pa, a diffusion pump is used to evacuate to below 5x10 -3 Pa, then the diffusion pump is closed, and high-purity argon is filled to form a protective gas atmosphere. During melting, the initial current is set to 400 A. Then the current is gradually increased at a rate of 50 A / 2 min to ensure uniform heat transfer. After the current is stably increased to about 850 A, the crucible is shaken several times to promote the mixing of different components. After the alloy liquid remains red for 10 min, the current is reduced to 700 A for 5 min. Finally, the molten alloy is poured into a copper mold and cooled in a vacuum environment for 20-30 min, thereby obtaining an alloy ingot with relatively uniform component distribution.

[0033] (2) The obtained alloy ingot is spun into an iron-silicon-aluminum alloy strip.

[0034] Specifically, the alloy ingot obtained in step (1) is removed from the surface oxide layer, and then subjected to crushing and cleaning treatment. Then the alloy ingot is heated until completely melted, and the metal liquid stream is sprayed onto the surface of the copper roller to obtain an iron-silicon-aluminum alloy strip.

[0035] In some embodiments, the spinning speed of the alloy ingot is 35-45 m / s; the width of the iron-silicon-aluminum alloy strip is 1-1.5 mm, and the thickness is 20-30 μm.

[0036] For example, step (2) is specifically: The alloy ingot obtained in step (1) needs to be first removed of its surface oxide layer by a grinding machine, and then crushed and cleaned. The quartz tube containing the alloy ingot is placed in the heating coil of a ribbon caster, and then the furnace door is closed. High-purity argon is introduced for 3 times of gas washing, and then the system is vacuumed to below 10 Pa by a mechanical pump, and high-purity argon is filled to form a protective atmosphere, while the pressure difference is adjusted to 0.13 MPa, and then the alloy ingot is heated until completely melted, and the metal liquid is sprayed onto the surface of a copper roller to obtain an iron-silicon-aluminum alloy strip.

[0037] The present application can adjust the magnetic properties and initial structure of the alloy by adjusting the mass ratio of iron, silicon and aluminum (85:9.0~10.2:4.8~6.0), the spinning speed (35~45 m / s) and the size of the strip.

[0038] The present application also provides a sheet-shaped wave-absorbing soft magnetic composite material prepared by the above method. The material has excellent electromagnetic wave absorption performance.

[0039] The embodiments of the present application will be described in detail below with specific examples, but those skilled in the art will understand that the following examples are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. Based on the examples in the present application, all other examples obtained by those skilled in the art without creative labor are within the scope of the present application. If the specific conditions are not specified, the conventional conditions or the conditions recommended by the manufacturer are used. If the manufacturer of the reagent or instrument is not specified, it is a conventional product that can be purchased on the market.

[0040] It should be noted that: In the present application, all the embodiments and preferred implementation methods mentioned in the present application can be combined to form new technical solutions, unless otherwise specified.

[0041] In the present application, all the technical features and preferred features mentioned in the present application can be combined to form new technical solutions, unless otherwise specified.

[0042] In the present application, unless otherwise specified, the percentage (%) or the part refers to the percentage by weight or the weight part of the composition.

[0043] In the present application, unless otherwise specified, each component or its preferred component involved can be combined to form a new technical solution.

[0044] In the present application, unless otherwise specified, the "range" disclosed in the present application in the form of lower limit and upper limit can be one or more lower limits, and one or more upper limits, respectively.

[0045] In the present application, unless otherwise specified, each reaction or operation step can be carried out sequentially or not in order. Preferably, the reaction method herein is carried out sequentially.

[0046] Unless otherwise specified, the professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to that described can also be applied in the present application.

[0047] Example 1: A preparation method of a sheet-shaped wave-absorbing soft magnetic composite material, comprising the following steps: Step (1), pure iron, pure silicon and pure aluminum alloy raw materials with a mass ratio of Fe: Si: Al being 85: 9.6: 5.4 are inductively melted to obtain an alloy ingot.

[0048] The iron-based alloy raw materials are weighed according to the preset ratio, the ceramic crucible is placed in the heating coil, the furnace door is closed, the cavity of the induction melting furnace is pre-vacuumized by a mechanical pump, high-purity argon is used for 3 times of gas washing, when the vacuum degree reaches below 10 Pa, the diffusion pump is opened to vacuumize to below 5*10 -3 Pa, then the diffusion pump is closed, high-purity argon is filled to form a protective gas atmosphere. During melting, the initial current is set to 400 A. Then the current is gradually increased at an amplitude of 50 A / 2 min to ensure uniform heat transfer. After the current is stably increased to about 850 A, the alloy liquid is kept red and bright for 10 min by shaking the crucible multiple times to promote the mixing of different components. Then the current is reduced to 700 A for 5 min. Finally, the molten alloy is poured into a copper mold and cooled in a vacuum environment for 30 min, thereby obtaining an alloy ingot with relatively uniform composition distribution.

[0049] Step (2), the obtained alloy ingot is spun into an iron-silicon-aluminum alloy strip; The alloy ingot obtained in step (1) needs to be removed from its surface oxide layer by a grinding machine, and then crushed, washed and treated. The quartz tube containing the alloy ingot is placed in the heating coil of the spinning machine, and then the furnace door is closed. High-purity argon is introduced for 3 times of gas washing, then the system is vacuumized to below 10 Pa by a mechanical pump, high-purity argon is filled to form a protective atmosphere, the gas pressure difference is adjusted to 0.13 MPa, and then the alloy ingot is heated until it is completely melted, and the metal liquid is sprayed onto the surface of the copper roller to obtain an iron-silicon-aluminum alloy strip.

[0050] Step (3), the obtained iron-silicon-aluminum strip is crushed and ball milled to obtain a sheet-shaped iron-silicon-aluminum powder; The iron-silicon-aluminum strip is mechanically broken by using a high-energy pulverizer to convert it into primary powder particles. Then the iron-silicon-aluminum powder is added to a vacuum ball mill jar, and anhydrous ethanol is added as a medium, filled to about 50% of the volume of the jar, steel balls are selected as the grinding medium, the ball-to-material ratio is set to 20:1, and the ball milling time is 60 h. After ball milling, the ball mill jar is transferred to a vacuum drying oven for low-temperature drying, and finally the flaky iron-silicon-aluminum powder is obtained.

[0051] Step (4), the obtained flaky iron-silicon-aluminum powder is subjected to a controllable oxygen partial pressure high-temperature heat treatment in an atmosphere of oxygen and argon, wherein the oxygen partial pressure volume concentration is 1%, the controllable oxygen partial pressure heat treatment time is 20 min, and the controllable oxygen partial pressure heat treatment temperature is 650°C. Finally, a flaky iron-silicon-aluminum composite material coated with silicon oxide and aluminum oxide on the surface is obtained, which has excellent electromagnetic wave absorption performance, i.e., the flaky wave-absorbing soft magnetic composite material.

[0052] The phase structure of the obtained flaky iron-silicon-aluminum composite material is measured by an X-ray diffractometer, as shown in FIG. 2. Figure 1

[0053] The wave-absorbing performance of the obtained flaky iron-silicon-aluminum composite material is tested by a vector network analyzer, as shown in Table 1.

[0054] Example 2: A preparation method of a flaky wave-absorbing soft magnetic composite material, comprising the following steps: Step (1), an alloy ingot is obtained by induction melting of pure iron, pure silicon, and pure aluminum alloy raw materials in a proper proportion.

[0055] The iron-based alloy raw materials are weighed according to the preset ratio, put into an induction melting furnace, and melted and mixed into a uniform alloy liquid. The molten alloy is poured into a copper mold and cooled in a vacuum environment for 30 min, thereby obtaining an alloy ingot with relatively uniform composition distribution.

[0056] Step (2), the obtained alloy ingot is spun to obtain an iron-silicon-aluminum alloy strip; The alloy ingot obtained in step (1) is removed of its surface oxide layer, and then subjected to breaking and cleaning treatment. Then the alloy ingot is heated until completely melted, and the metal liquid stream is sprayed onto the surface of a copper roller to obtain an iron-silicon-aluminum alloy strip.

[0057] Step (3), the obtained iron-silicon-aluminum strip is broken and ball milled to obtain flaky iron-silicon-aluminum powder; The iron-silicon-aluminum strip is mechanically broken by using a high-energy pulverizer to convert it into primary powder particles. Then the iron-silicon-aluminum powder is added to a ball mill jar, and anhydrous ethanol and steel balls are added for ball milling. After ball milling, the ball mill jar is transferred to a vacuum drying oven for low-temperature drying, and finally the flaky iron-silicon-aluminum powder is obtained.

[0058] ​Step (4), the obtained flaky iron-silicon-aluminum powder is subjected to high-temperature heat treatment under a controllable oxygen partial pressure in an atmosphere of oxygen and argon, wherein the oxygen partial pressure volume concentration is 1%, the controllable oxygen partial pressure heat treatment time is 20 min, and the controllable oxygen partial pressure heat treatment temperature is 750 ℃, and finally a flaky iron-silicon-aluminum composite material coated with silicon oxide and aluminum oxide on the surface is obtained, and the material has excellent electromagnetic wave absorption performance, that is, the flaky wave-absorbing soft magnetic composite material.

[0059] This example only changes the controllable oxygen partial pressure heat treatment temperature compared with example 1, and the rest of the parameters are the same as example 1.

[0060] Example 3: A preparation method of a flaky wave-absorbing soft magnetic composite material, comprising the following steps: Step (1), inductively melting pure iron, pure silicon and pure aluminum alloy raw materials in a proper proportion to obtain an alloy ingot.

[0061] The iron-based alloy raw materials are weighed according to the preset ratio, put into an induction melting furnace, melted and mixed into a uniform alloy liquid, and the molten alloy is poured into a copper mold and cooled in a vacuum environment for 30 min, thereby obtaining an alloy ingot with relatively uniform composition distribution.

[0062] Step (2), the obtained alloy ingot is subjected to tape casting to obtain an iron-silicon-aluminum alloy strip; The alloy ingot obtained in step (1) is removed from the surface oxide layer, and then subjected to crushing and cleaning treatment. Then the alloy ingot is heated until completely melted, and the metal liquid stream is sprayed onto the surface of the copper roller to obtain an iron-silicon-aluminum alloy strip.

[0063] Step (3), the obtained iron-silicon-aluminum strip is crushed and ball milled to obtain a flaky iron-silicon-aluminum powder; The iron-silicon-aluminum strip is mechanically crushed using a high-energy crusher to convert it into primary powder particles. Then the iron-silicon-aluminum powder is added to a ball mill tank, and anhydrous ethanol and steel balls are added for ball milling. After ball milling, the ball mill tank is transferred to a vacuum drying box for low-temperature drying, and finally a flaky iron-silicon-aluminum powder is obtained.

[0064] Step (4), the obtained flaky iron-silicon-aluminum powder is subjected to high-temperature heat treatment under a controllable oxygen partial pressure in an atmosphere of oxygen and argon, wherein the oxygen partial pressure concentration is 1%, the controllable oxygen partial pressure heat treatment time is 20 min, and the controllable oxygen partial pressure heat treatment temperature is 850 ℃, and finally a flaky iron-silicon-aluminum composite material coated with silicon oxide and aluminum oxide on the surface is obtained, and the material has excellent electromagnetic wave absorption performance, that is, the flaky wave-absorbing soft magnetic composite material.

[0065] This example only changes the controllable oxygen partial pressure heat treatment temperature compared with example 1, and the rest of the parameters are the same as example 1.

[0066] Figure 2 and Figure 3It is a microstructure diagram of the embodiment, wherein Figure 2 It is an electron microscope diagram of the flaky iron-silicon-aluminum powder after ball milling, 1500 times. Figure 3 It is an electron microscope diagram of the flaky iron-silicon-aluminum composite material after the controllable oxygen partial pressure heat treatment, 2000 times.

[0067] Comparative Example 1: A flaky wave-absorbing soft magnetic composite material is prepared by using a controllable oxygen partial pressure low-temperature heat treatment method The comparative example prepares a preparation method of a flaky wave-absorbing soft magnetic composite material, comprising the following steps: Step (1), the pure iron, the pure silicon, and the pure aluminum alloy raw materials in a proper proportion are inductively melted to obtain an alloy ingot.

[0068] The iron-based alloy raw materials are weighed according to a preset ratio, put into an induction melting furnace, and melted and mixed into a uniform alloy liquid. The molten alloy is poured into a copper mold and cooled in a vacuum environment for 30 min, thereby obtaining an alloy ingot with a relatively uniform composition distribution.

[0069] Step (2), the obtained alloy ingot is spun to obtain an iron-silicon-aluminum alloy strip; The alloy ingot obtained in step (1) is removed of the surface oxide layer, and then is crushed and cleaned. Then the alloy ingot is heated until completely melted, and the metal liquid stream is sprayed onto the surface of a copper roller to obtain an iron-silicon-aluminum alloy strip.

[0070] Step (3), the obtained iron-silicon-aluminum strip is crushed and ball milled to obtain flaky iron-silicon-aluminum powder; The iron-silicon-aluminum strip is mechanically crushed using a high-energy crusher to convert it into primary powder particles. Then the iron-silicon-aluminum powder is added to a ball mill tank, and anhydrous ethanol and steel balls are added for ball milling. After ball milling, the ball mill tank is transferred to a vacuum drying box for low-temperature drying, and finally flaky iron-silicon-aluminum powder is obtained.

[0071] Step (4), the obtained flaky iron-silicon-aluminum powder is subjected to controllable oxygen partial pressure high-temperature heat treatment in an atmosphere of oxygen and argon, wherein the oxygen partial pressure volume concentration is 1%, the controllable oxygen partial pressure heat treatment time is 20 min, and the controllable oxygen partial pressure heat treatment temperature is 450°C, and finally a flaky iron-silicon-aluminum composite material is obtained.

[0072] The comparative example changes only the controllable oxygen partial pressure heat treatment temperature compared with the embodiment 1, and the other parameters are the same as those of the embodiment 1.

[0073] Comparative Example 2: A flaky wave-absorbing soft magnetic composite material is prepared by using a short-time controllable oxygen partial pressure high-temperature heat treatment method The comparative example prepares a preparation method of a flaky wave-absorbing soft magnetic composite material, comprising the following steps: Step (1), the pure iron, the pure silicon, and the pure aluminum alloy raw materials in a proper proportion are inductively melted to obtain an alloy ingot.

[0074] The iron-based alloy raw materials are weighed according to the preset proportion, put into an induction melting furnace, melted and mixed into a uniform alloy liquid, the molten alloy is poured into a copper mold, and cooled under vacuum for 30 min, thereby obtaining an alloy ingot with relatively uniform component distribution.

[0075] Step (2), the obtained alloy ingot is spun into an iron-silicon-aluminum alloy strip; The alloy ingot obtained in step (1) is removed of the surface oxide layer, then crushed and washed. Then the alloy ingot is heated until completely melted, and the metal liquid stream is sprayed onto the surface of the copper roller to obtain an iron-silicon-aluminum alloy strip.

[0076] Step (3), the obtained iron-silicon-aluminum alloy strip is crushed and ball milled to obtain a flaky iron-silicon-aluminum powder; The iron-silicon-aluminum alloy strip is mechanically crushed using a high-energy crusher to convert it into primary powder particles. Then the iron-silicon-aluminum powder is added to a ball mill tank, and anhydrous ethanol and steel balls are added for ball milling. After ball milling, the ball mill tank is transferred to a vacuum drying oven for low-temperature drying, and finally a flaky iron-silicon-aluminum powder is obtained.

[0077] Step (4), the obtained flaky iron-silicon-aluminum powder is subjected to controllable oxygen partial pressure high-temperature heat treatment in an atmosphere of oxygen and argon, wherein the oxygen partial pressure volume concentration is 1%, the controllable oxygen partial pressure heat treatment time is 10 min, and the controllable oxygen partial pressure heat treatment temperature is 650°C, and finally a flaky iron-silicon-aluminum composite material is obtained.

[0078] The present comparative example only changes the controllable oxygen partial pressure heat treatment time compared to example 1, and the rest of the parameters are the same as example 1.

[0079] Comparative example 3: the heat treatment atmosphere uses pure argon The present comparative example prepares a method for preparing a flaky wave-absorbing soft magnetic composite material, comprising the following steps: Step (1), the pure iron, pure silicon and pure aluminum alloy raw materials are inducted to obtain an alloy ingot.

[0080] The iron-based alloy raw materials are weighed according to the preset proportion, put into an induction melting furnace, melted and mixed into a uniform alloy liquid, the molten alloy is poured into a copper mold, and cooled under vacuum for 30 min, thereby obtaining an alloy ingot with relatively uniform component distribution.

[0081] Step (2), the obtained alloy ingot is spun into an iron-silicon-aluminum alloy strip; The alloy ingot obtained in step (1) is removed of the surface oxide layer, then crushed and washed. Then the alloy ingot is heated until completely melted, and the metal liquid stream is sprayed onto the surface of the copper roller to obtain an iron-silicon-aluminum alloy strip.

[0082] Step (3), the obtained iron-silicon-aluminum strip is crushed and ball milled to obtain flaky iron-silicon-aluminum powder; The iron-silicon-aluminum strip is mechanically crushed by using a high-energy crusher to convert it into primary powder particles. Then the iron-silicon-aluminum powder is added to a ball mill tank, and anhydrous ethanol and steel balls are added for ball milling. After ball milling, the ball mill tank is transferred to a vacuum drying oven for low-temperature drying, and finally flaky iron-silicon-aluminum powder is obtained.

[0083] Step (4), the obtained flaky iron-silicon-aluminum powder is subjected to high-temperature heat treatment in an argon atmosphere, wherein the heat treatment time is 20 min and the heat treatment temperature is 750 ℃, and finally flaky iron-silicon-aluminum composite material is obtained.

[0084] The comparative example changes the controllable oxygen partial pressure heat treatment to ordinary high-temperature heat treatment, i.e. the atmosphere is argon atmosphere without oxygen, compared with example 1. The rest of the parameters are the same as example 1.

[0085] The flaky wave-absorbing soft magnetic composite material provided by the example and the comparative example is measured by using a vector network analyzer, and the test results are shown in Table 1 as follows: Table 1 Performance test results of flaky wave-absorbing soft magnetic composite material As shown in the above table, the flaky wave-absorbing soft magnetic composite material prepared in examples 1-3 has a minimum reflection loss value of about -55 dB, and the effective absorption bandwidth can reach about 6.4 GHz. Compared with the material prepared in comparative example 1 at low temperature and comparative example 2 with short heat treatment time, the effective absorption bandwidth is more excellent, and compared with comparative example 3, the minimum reflection loss value is more excellent. The flaky wave-absorbing soft magnetic composite material provided by the present application has excellent electromagnetic wave absorption characteristics.

[0086] The above examples are not a limitation of the present application, and the present application is not limited to the above examples, as long as it meets the requirements of the present application, it belongs to the protection scope of the present application.

Claims

1. A method for preparing a sheet-shaped wave-absorbing soft magnetic composite material, characterized by, The preparation method comprises: The iron-silicon-aluminum alloy is crushed and ball milled to obtain flaky iron-silicon-aluminum powder; the obtained flaky iron-silicon-aluminum powder is subjected to controllable oxygen partial pressure high-temperature heat treatment in an inert atmosphere containing oxygen with a volume fraction of 1-3%, at a temperature greater than 650°C, to obtain a flaky wave-absorbing soft magnetic composite material; the flaky wave-absorbing soft magnetic composite material has a core-shell structure, with the flaky iron-silicon-aluminum particles as the core and a composite oxide layer composed of silicon oxide and aluminum oxide as the shell.

2. The method of claim 1, wherein, The mass ratio of iron, silicon and aluminum in the iron-silicon-aluminum alloy is 85:(9.0-10.2):(4.8-6.0).

3. The method of claim 1, wherein, The ball milling conditions are that anhydrous ethanol is used as the medium, the ball-to-material ratio is 20:1, and the ball milling time is 48-60 h.

4. The method of claim 1 or 3, wherein, The thickness of the flaky iron-silicon-aluminum powder after ball milling is 1.5-2 μm, and the diameter-to-thickness ratio is 9.5-11.

5.

5. The method of claim 1, wherein, The inert gas in the inert atmosphere is argon.

6. The method of claim 1 or 5, wherein, The controllable oxygen partial pressure high-temperature heat treatment temperature is 650-850°C, and the time is 20-30 min.

7. The method of claim 1, wherein, The iron-silicon-aluminum alloy is prepared by induction melting of pure iron, pure silicon and pure aluminum alloy raw materials to obtain an alloy ingot; the obtained alloy ingot is spun to obtain an iron-silicon-aluminum alloy strip.

8. The method of claim 7, wherein, The induction melting atmosphere in the preparation of the iron-silicon-aluminum alloy is high-purity argon, and the pressure is 0.06-0.08 Mpa.

9. The method of claim 7, wherein, The alloy ingot spinning speed is 35-45 m / s; the width of the iron-silicon-aluminum strip is 1-1.5 mm, and the thickness is 20-30 μm. 10.A flaky wave-absorbing soft magnetic composite material prepared by the method of any one of claims 1-9.

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