High-frequency magnetic composite material and preparation method and application thereof

Abstract

The application belongs to the technical field of magnetic materials, and particularly relates to a high-frequency magnetic composite material and a preparation method and application thereof. The high-frequency magnetic composite material comprises the following raw materials in terms of mass fraction: 94.5-98% of nanocrystalline alloy powder, 1-5% of a core-shell coating layer and 0.1-0.5% of rare earth oxide. The high-frequency magnetic composite material prepared by mixing the nanocrystalline alloy powder, the core-shell coating layer and the rare earth oxide and using a low-temperature and low-pressure process significantly reduces the loss of the material and improves the magnetic permeability of the material.

Description

Technical Field

[0001] This invention belongs to the field of magnetic materials technology, specifically relating to a high-frequency magnetic composite material, its preparation method, and its application. Background Technology

[0002] As electronic devices evolve towards higher frequencies, miniaturization, and higher power density, the performance bottleneck of inductors, as one of the core components of power electronic systems, is becoming increasingly apparent. Magnetic devices such as inductors, transformers, and power supplies face challenges related to high frequency, high efficiency, and high energy density, necessitating development towards higher frequency, higher efficiency, and smaller size applications. Electronic devices are rapidly evolving towards higher frequencies, integration, and lower power consumption, especially with the rapid development of third-generation power semiconductors, creating an urgent demand for high-frequency magnetic materials with cutoff frequencies in the megahertz range. Traditional wire-wound inductors, due to their large size and significant high-frequency losses, can no longer meet the miniaturization and high efficiency requirements of modern electronic devices. This contradiction has driven the continuous development of technologies represented by molded inductors. Molded inductors, through their fully enclosed structural design, achieve miniaturization and higher frequencies while placing higher demands on the magnetic materials supporting their performance.

[0003] Ferrite cores and pressed powder cores are known to be used as choke coils in the high-frequency region. A drawback of ferrite cores is their relatively low saturation flux density. On the other hand, pressed powder cores, made from molded metallic magnetic powder, have a much higher saturation flux density than ferrite cores, which is advantageous for core miniaturization. However, it cannot be said that pressed powder cores are superior to ferrite cores in terms of permeability and power loss. Therefore, when pressed powder cores are used in choke coils and induction coils, their core losses are relatively high, leading to a greater increase in core temperature, which in turn hinders core miniaturization.

[0004] For example, Chinese patent CN115064372B belongs to the field of magnetic materials technology, specifically involving a high-frequency magnetic composite material, a high-frequency magnetic device, and its processing method. The processing method for the high-frequency magnetic composite material includes: mixing and grinding magnetic metal particles with a magnetic vortex structure, a solvent, and a non-magnetic ceramic phase material into a slurry; placing the slurry in a mold and molding it under a low-temperature, low-pressure process; wherein the conditions for the low-temperature, low-pressure process are a temperature below 300℃ and a pressure below 500MPa. This invention, by using magnetic particles with a magnetic vortex structure, eliminates magnetic domain walls, and magnetization at high frequencies is primarily based on magnetization rotation rather than the traditional domain wall displacement mechanism, significantly increasing the material's operating frequency to above 100MHz. Furthermore, the low-temperature, low-pressure process avoids various defects caused by extreme conditions such as high temperature and high pressure in traditional processes. However, this invention may reduce material density, leading to insufficient mechanical strength or internal defects, affecting long-term stability, and making it prone to failure, especially in high-stress applications. Moreover, the high investment cost limits large-scale application.

[0005] For example, in his doctoral dissertation "Preparation and High-Frequency Magnetic Study of Magnetic Micron and Nanomaterials," Ma Zhi first studied cobalt materials with different morphologies and their microwave absorption properties; secondly, he studied the microwave absorption properties of micron-sized octahedral iron oxide; and thirdly, he systematically studied the microwave absorption mechanism and properties of four types of composite materials. The study found that the effective dielectric constant and effective permeability of core-shell symmetrical composite materials are determined by the radius of the core or the thickness of the shell and the mass percentage of the insulating and magnetic phases. By adjusting the ratio of the insulating and magnetic phases in the composite structure, the effective dielectric constant and permeability of the sample can be effectively adjusted.

[0006] The impedance matching theory can be used to adjust the input impedance of the sample to achieve better impedance matching, thus providing guidance for the preparation of microwave absorbers with a wider bandwidth. However, this invention lacks high-frequency applicability because it does not perform dispersion characteristic analysis of complex permeability, resulting in impedance matching theory being only applicable to low-frequency narrowband scenarios.

[0007] Therefore, there is an urgent need to study a magnetic composite material that can work stably at high frequencies. Summary of the Invention

[0008] In view of the shortcomings of the existing technology, the present invention aims to provide a high-frequency magnetic composite material, its preparation method and application.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] On the one hand, the present invention provides a high-frequency magnetic composite material, which, by mass fraction, comprises the following raw materials: 94.5-98% nanocrystalline alloy powder, 1-5% core-shell coating layer and 0.1-0.5% rare earth oxides.

[0011] Preferably, the high-frequency magnetic composite material comprises, by mass fraction, the following raw materials: 96% nanocrystalline alloy powder, 3.7% core-shell coating layer, and 0.3% rare earth oxides.

[0012] Preferably, the nanocrystalline alloy powder is selected from one of iron-silicon, iron-silicon-aluminum, iron-nickel, iron-nickel-chromium, iron-silicon-chromium, iron-silicon-nickel, iron-nickel-molybdenum, iron-cobalt, and iron-cobalt-silicon.

[0013] More preferably, the nanocrystalline alloy powder is iron-silicon-aluminum (Fe-Si-Al).

[0014] Preferably, the preparation method of the iron-silicon-aluminum nanocrystalline alloy powder is as follows:

[0015] Reduced iron powder, aluminum powder, and monocrystalline silicon powder are mixed in a mass ratio of 80-85:5-10:5-10, and ball milled in a ball mill jar filled with protective gas to obtain the final product.

[0016] Preferably, the preparation method of the iron-silicon-aluminum nanocrystalline alloy powder is as follows:

[0017] Reduced iron powder (purity ≥98%), aluminum powder (purity ≥99%), and monocrystalline silicon powder (purity ≥99%) were mixed in a mass ratio of 85:9:6 and placed in a hard chrome steel ball mill jar for ball milling. A FRITSCH pulverisette 4 planetary ball mill was used, with a ball-to-material mass ratio of 10:1, a main disk speed of 200 r / min, and a planetary disk speed of 350 r / min. To prevent oxidation, the ball mill jar was filled with high-purity argon gas (purity ≥99.99%) as a protective gas. The weighing, loading, and sampling of the raw materials were all carried out in a glove box filled with high-purity argon gas. The ball milling was carried out for 40 hours to obtain the final product.

[0018] Preferably, the core-shell coating is selected from at least two of alumina, titanium dioxide, molybdenum trioxide, zinc oxide, and boron trioxide.

[0019] More preferably, the core-shell coating is composed of alumina and titanium oxide, wherein the mass ratio of alumina to titanium oxide is 1:28-32, more preferably 1:30.

[0020] Preferably, the rare earth oxide is selected from one of dysprosium oxide, terbium oxide, samarium oxide, neodymium oxide, erbium oxide, and gadolinium oxide.

[0021] More preferably, the rare earth oxide is dysprosium oxide (Dy2O3).

[0022] As some preferred embodiments, the high-frequency magnetic composite material comprises, by mass fraction, the following raw materials: 94.5-98% Fe-Si-Al nanocrystalline alloy powder, 1-5% Al2O3 / TiO2 core-shell coating layer and 0.1-0.5% Dy2O3.

[0023] As a preferred embodiment, the high-frequency magnetic composite material comprises, by mass fraction, the following raw materials: 96% Fe-Si-Al nanocrystalline alloy powder, 3.7% Al2O3 / TiO2 core-shell coating layer and 0.3% Dy2O3.

[0024] On the other hand, the present invention also provides a method for preparing the above-mentioned high-frequency magnetic composite material, comprising the following steps:

[0025] (1) Mix and grind the nanocrystalline alloy powder, core-shell coating, rare earth oxide and solvent into a slurry;

[0026] (2) The mud is placed in a mold and shaped to obtain the desired product.

[0027] Preferably, the solvent in step (1) is selected from water, ethanol, acetic acid solution, citric acid solution, and oxalic acid solution, and more preferably water.

[0028] Preferably, the mass fraction of solvent in the mud in step (1) is 5-20%, more preferably 18%.

[0029] Preferably, the process described in step (2) is a low-temperature and low-pressure process, specifically: heating to 250-300℃ at 8-10℃ / min, while applying a pressure of 250-400MPa, and holding the pressure for 1-2 hours to obtain the final product.

[0030] More preferably, the process described in step (2) is a low temperature and low pressure process, specifically: the temperature is increased to 300℃ at 10℃ / min, and a pressure of 300MPa is applied at the same time, and the pressure is maintained for 1h to obtain the product.

[0031] Finally, the present invention also provides the application of the above-mentioned frequency magnetic composite material in the fabrication of electronic devices.

[0032] Specifically, the electronic device is a transformer, rectifier, or inductor.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] This invention produces a high-frequency magnetic hybrid material by mixing nanocrystalline alloy powder, a core-shell coating layer, and rare earth oxides, and preparing it using a low-temperature and low-pressure process. This significantly reduces material loss and improves the material's magnetic permeability. Detailed Implementation

[0035] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the materials and reagents used are commercially available.

[0036] The iron-silicon-aluminum nanocrystalline alloy powders described in the following examples and comparative examples were prepared by the following methods:

[0037] Reduced iron powder (purity ≥98%), aluminum powder (purity ≥99%), and monocrystalline silicon powder (purity ≥99%) were mixed in a mass ratio of 85:9:6 and placed in a hard chrome steel ball mill jar for ball milling. A FRITSCH pulverisette 4 planetary ball mill was used, with a ball-to-material mass ratio of 10:1, a main disk speed of 200 r / min, and a planetary disk speed of 350 r / min. To prevent oxidation, the ball mill jar was filled with high-purity argon gas (purity ≥99.99%) as a protective gas. The weighing, loading, and sampling of the raw materials were all carried out in a glove box filled with high-purity argon gas. The ball milling was carried out for 40 hours to obtain the final product.

[0038] Example 1: A high-frequency magnetic composite material

[0039] By mass fraction, it consists of the following raw materials:

[0040] 96% Fe-Si-Al nanocrystalline alloy powder, 3.7% Al2O3 / TiO2 core-shell coating (Al2O3 and TiO2 mass ratio is 1:30) and 0.3% Dy2O3.

[0041] Example 2: A high-frequency magnetic composite material

[0042] By mass fraction, it consists of the following raw materials:

[0043] 97.9% Fe-Si-Al nanocrystalline alloy powder, 1% Al2O3 / TiO2 core-shell coating (mass ratio of Al2O3 to TiO2 is 1:28) and 0.1% Dy2O3.

[0044] Example 3: A high-frequency magnetic composite material

[0045] By mass fraction, it consists of the following raw materials:

[0046] 94.5% Fe-Si-Al nanocrystalline alloy powder, 5% Al2O3 / TiO2 core-shell coating (Al2O3 and TiO2 mass ratio is 1:32) and 0.5% Dy2O3.

[0047] Comparative Example 1: A High-Frequency Magnetic Composite Material

[0048] By mass fraction, it consists of the following raw materials:

[0049] 90% Fe-Si-Al nanocrystalline alloy powder, 8% Al2O3 / TiO2 core-shell coating layer and 2% Dy2O3.

[0050] Comparative Example 2

[0051] The difference from Example 1 is that the core-shell coating layer is only TiO2, while the rest is the same as in Example 1.

[0052] Comparative Example 3

[0053] The difference from Example 1 is that Dy2O3 is replaced with lanthanum oxide, otherwise it is the same as Example 1.

[0054] The above Examples 1-3 and Comparative Examples 1-3 were prepared according to the following method:

[0055] (1) Mix and grind the nanocrystalline alloy powder, core-shell coating, rare earth oxide and water into a slurry according to the proportion (the mass fraction of water in the slurry is 18%).

[0056] (2) Place the mud in a mold and heat it to 300℃ at 10℃ / min, while applying a pressure of 300MPa and holding the pressure for 1h to obtain the mud.

[0057] Effect Experiment

[0058] The high-frequency magnetic composite materials prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to magnetic permeability testing. The initial magnetic permeability μ of the samples was measured using a 3260B LCR meter. i The maximum permeability μ of the high-frequency magnetic composite material was measured using a BH analyzer (BHLDT-400V). max And power loss at different temperatures and frequencies.

[0059] Table 1

[0060]

[0061] As can be seen from the data in Table 1, the high-frequency magnetic composite material prepared in the embodiments of the present invention has the characteristics of low loss and high magnetic permeability.

[0062] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A high-frequency magnetic composite material, characterized in that, By mass fraction, it includes the following raw materials: 94.5-98% nanocrystalline alloy powder, 1-5% core-shell coating layer and 0.1-0.5% rare earth oxides; The nanocrystalline alloy powder is selected from one of the following: iron-silicon, iron-silicon-aluminum, iron-nickel, iron-nickel-chromium, iron-silicon-chromium, iron-silicon-nickel, iron-nickel-molybdenum, iron-cobalt, and iron-cobalt-silicon. The core-shell coating is composed of aluminum oxide and titanium oxide, with a mass ratio of aluminum oxide to titanium oxide of 1:28-32; The rare earth oxides are selected from one of dysprosium oxide, terbium oxide, samarium oxide, neodymium oxide, erbium oxide, and gadolinium oxide.

2. The high-frequency magnetic composite material according to claim 1, characterized in that, By mass fraction, it includes the following raw materials: 96% nanocrystalline alloy powder, 3.7% core-shell coating layer and 0.3% rare earth oxides.

3. The high-frequency magnetic composite material according to claim 1, characterized in that, The preparation method of the iron-silicon-aluminum nanocrystalline alloy powder is as follows: reduced iron powder, aluminum powder and single crystal silicon powder are mixed in a mass ratio of 80-85:5-10:5-10, and ball milling is carried out in a ball mill jar filled with protective gas to obtain the powder.

4. The method for preparing the high-frequency magnetic composite material according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Mix and grind the nanocrystalline alloy powder, core-shell coating, rare earth oxide and solvent into a slurry; (2) The mud is placed in a mold and shaped to obtain the desired product.

5. The preparation method according to claim 4, characterized in that, The process described in step (2) is a low-temperature and low-pressure process. The specific operation is as follows: the temperature is increased to 250-300℃ at 8-10℃ / min, and the pressure is applied at 250-400MPa and held for 1-2 hours.

6. The use of the high-frequency magnetic composite material according to any one of claims 1-3 or the high-frequency magnetic composite material prepared by the preparation method according to any one of claims 4-5 in the manufacture of electronic devices.

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