Magnetic core having high magnetic permeability, preparation method therefor and use thereof

Abstract

The present invention belongs to the field of magnetic materials. Specifically, disclosed are a magnetic core having high magnetic permeability, a preparation method therefor and the use thereof. In the method of the present invention, two heat treatments are first performed at a certain pressure and temperature, and then a magnetic field heat treatment is performed to induce an amorphous magnetic core to realize nanocrystallization and crystalline grain homogenization, thereby effectively solving the problems of uneven nucleation and excessive growth of nanocrystalline grains in conventional heat treatments, comprehensively improving the magnetic permeability of the magnetic core at different frequencies, and achieving the purpose of improving the full-band magnetic permeability of the magnetic core to the greatest extent.

Description

A high-permeability magnetic core, its fabrication method and application Technical Field

[0001] This invention belongs to the field of magnetic materials, specifically relating to a high-permeability magnetic core, its preparation method, and its applications. Background Technology

[0002] Iron-based amorphous / nanocrystalline soft magnetic alloys are typically produced by rapidly cooling a master alloy with high-speed copper rollers to create amorphous strips, which are then wound into amorphous magnetic cores. Amorphous magnetic cores generally require appropriate heat treatment processes to precisely control the alloy's microstructure. This involves transforming the precipitation of a single magnetic α-Fe phase on the amorphous matrix into a dual-phase structure of amorphous and nanocrystalline components, thus forming the magnetic core. This unique dual-phase nanostructure is the main reason why the magnetic core exhibits excellent overall soft magnetic properties. Therefore, the heat treatment process plays a decisive role in obtaining high-performance magnetic cores.

[0003] In conventional heat treatment methods for amorphous magnetic cores, such as annealing in an atmosphere furnace, incomplete grain precipitation, uneven grain precipitation, and excessive grain growth often occur under high-temperature heat treatment. All of these issues deteriorate the performance of the obtained magnetic core, particularly significantly reducing its permeability. Furthermore, permeability varies at different frequencies, meaning the degree of permeability improvement from heat treatment varies across different frequency bands. Therefore, conventional magnetic cores cannot maintain peak permeability across different frequency ranges. Consequently, existing heat treatment processes have significant limitations in improving magnetic core permeability, necessitating the development of a new magnetic core fabrication technology to maximize permeability improvement. Summary of the Invention

[0004] In view of the limitations of the heat treatment process in the prior art in improving the permeability of magnetic cores, the present invention will provide a high permeability magnetic core, its preparation method and application.

[0005] To achieve the above objectives, the following technical solutions are specifically included:

[0006] A method for preparing a magnetic core includes the following steps:

[0007] (1) The amorphous magnetic core is subjected to a first heat treatment and a second heat treatment in sequence. After cooling and depressurization, a pre-burnt magnetic core is obtained. The temperature of the first heat treatment is 400-480℃, the temperature of the second heat treatment is 490-540℃, the pressure of the first heat treatment is 50-100MPa, and the pressure of the second heat treatment is 90-160MPa.

[0008] (2) The pre-burnt magnetic core is subjected to magnetic field heat treatment and then cooled to obtain the magnetic core.

[0009] In the method of the present invention,

[0010] This invention first uses a first heat treatment to ensure uniform heating of the amorphous magnetic core, providing a foundation for a second heat treatment. Then, the temperature is increased to the second heat treatment temperature, and the pressure is further increased. Through a slow heating rate and a suitable holding time, sufficient time is ensured for grain precipitation at a higher temperature. Under the influence of air pressure, the grains grow slowly and uniformly, avoiding uneven heating due to overheating, incomplete grain precipitation due to insufficient holding time, or excessive grain growth due to excessive holding time. Finally, a magnetic field heat treatment is combined to completely orient the nanocrystals. The combined force field and magnetic field heat treatments ensure complete and uniform grain precipitation in the magnetic core, achieving the goal of improving the permeability of the magnetic core across the entire frequency band.

[0011] Preferably, in step (1), the duration of the first heat treatment is 70-180 min, and the heating rate of the first heat treatment is 1-30℃ / min.

[0012] Preferably, the second heat treatment lasts for 70-180 minutes, the heating rate for the second heat treatment is 1-5°C / min, and the cooling rate is 5-200°C / min.

[0013] In the method of the present invention, in step (1), the main purpose of the first heat treatment and the second heat treatment is to crystallize the amorphous magnetic core, which aims to promote the precipitation of a large number of fine α-Fe nanocrystals on the amorphous substrate; in step (2), while the grains in the magnetic core are precipitating and growing, the grains are induced to grow in orientation along the direction of the magnetic field by the action of the magnetic field, and appropriate magnetic anisotropy is introduced under the action of the external magnetic field; therefore, by controlling the precipitation, size and growth orientation of nanocrystals by the method of the present invention, the comprehensive soft magnetic properties of the obtained nanocrystalline magnetic core are improved.

[0014] Preferably, in step (1), the pressurization method of the first heat treatment and the second heat treatment is selected from at least one of pressurization by inert gas pressure and pressurization by die extrusion; the amorphous magnetic core in step (1) is made of amorphous strip wound together, and the magnetic field direction of the magnetic field heat treatment in step (2) is parallel to the width direction of the amorphous magnetic core.

[0015] Preferably, in step (1), the amorphous magnetic core comprises the following elements in atomic percentage: Fe 60-80%, Si 10-20%, B 0-10%, Cu 0-3%, Nb 0-5%, Ni 0-15%, Co 0-10%, and V 0-10%.

[0016] More preferably, the amorphous magnetic core is Fe. 73.5 Si 15.5B7Cu1Nb3, Fe 73.5 Si 15.5 B7Cu1V1Nb2、Fe 73.5 Si 13.5 B9Cu1Nb3, Fe 63.5 Ni 10 Si 15.5 B7Cu1Nb3, Fe 63.5 Co5Ni5Si 15.5 B7Cu1Nb3, Fe 68.5 Co5Si 15.5 At least one of B7Cu1Nb3.

[0017] Preferably, in step (1), the cooling and depressurization method is to first cool the system naturally to below 200°C, and then release the system pressure to atmospheric pressure, with a cooling rate of 10-500°C / min.

[0018] Preferably, in step (2), the temperature of the magnetic field heat treatment is 460-530℃, the time of the magnetic field heat treatment is 10-180min, and the magnetic field strength of the magnetic field heat treatment is 800-3000Gs.

[0019] Preferably, in step (2), the rate of heating to the magnetic field heat treatment temperature is 1-20℃ / min.

[0020] Preferably, in step (2), the cooling method is natural cooling.

[0021] Preferably, the magnetic permeability of the magnetic core is greater than or equal to 35,000.

[0022] More preferably, the permeability of the magnetic core is 160,000-250,000 at a frequency of 1 kHz, 140,000-200,000 at a frequency of 10 kHz, and 35,000-40,000 at a frequency of 100 kHz.

[0023] More preferably, the magnetic core contains nano-sized α-Fe grains.

[0024] The present invention also provides an application of the magnetic core described above in the manufacture of new energy vehicles, photovoltaic energy storage devices, electronic camera devices, and 5G communication devices. The magnetic core of the present invention has high magnetic permeability and is more suitable for use in the manufacture of the above-mentioned devices.

[0025] Compared with the prior art, the present invention has the following beneficial effects: In the method of the present invention, the amorphous magnetic core is induced to achieve nanocrystallization and grain homogenization by first undergoing two heat treatments under certain pressure and temperature, and then by magnetic field heat treatment. This effectively solves the problems of uneven nucleation and excessive growth of nanocrystals in conventional heat treatment, comprehensively improves the permeability of the magnetic core at different frequencies, and achieves the goal of maximizing the permeability of the magnetic core across the entire frequency band. Attached Figure Description

[0026] Figure 1 shows the X-ray diffraction (XRD) pattern of the self-made amorphous ribbon.

[0027] Figure 2 is a comparison diagram of the magnetic domain structure between Example 1 (left) and Comparative Example 5 (right).

[0028] Figure 3 is a physical image of the magnetic core prepared in Example 1.

[0029] Figure 4 shows the relationship between the effective permeability and frequency of the iron-based nanocrystalline soft magnetic alloy cores in Examples 1-13.

[0030] Figure 5 shows the relationship between the effective permeability and frequency of the iron-based nanocrystalline soft magnetic alloy cores in Comparative Examples 1–5. Detailed Implementation

[0031] To better illustrate the purpose, technical solution, and advantages of this invention, specific embodiments will be used to further explain the invention below. Unless otherwise specified, the test methods used in the embodiments and / or comparative examples are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available.

[0032] Amorphous ribbons can be made in-house or purchased commercially. The amorphous ribbons used below are homemade, in which Fe... 73.5 Si 15.5 B7Cu1V1Nb2XRD is shown in Figure 1; the self-made method may include the following process: (1) component ratio; (2) master alloy melting; (3) then through strip spinning and strip winding to obtain the corresponding amorphous strip.

[0033] Example 1

[0034] (1) The alloy Fe, in atomic percentage terms 73.5 Si 15.5 B7Cu1V1Nb2 amorphous ribbon is wound into an amorphous magnetic core, and then the amorphous magnetic core is placed in a gas furnace. The furnace is evacuated and filled with inert argon gas to create a certain pressure in the system. The core is heated to the temperature of the first heat treatment, 430°C, at a heating rate of 15°C / min. At the same time, argon gas is continuously added to pressurize the system to the pressure of the first heat treatment, 60MPa. The system is then held at this temperature and pressure for 90 minutes.

[0035] (2) Continue heating and pressurizing at a heating rate of 3℃ / min to the second heat treatment temperature of 510℃, and at the same time continue to pressurize with argon gas to the second heat treatment pressure of 120MPa, and hold at this temperature and pressure for 90min; then cool down to below 200℃ and start to release the pressure to the chamber pressure, with the cooling rate set to natural cooling with the furnace, to obtain the pre-burnt magnetic core;

[0036] (2) Magnetic field heat treatment: The pre-burnt magnetic core is placed in the magnetic field heat treatment furnace and heated to 500°C at a heating rate of 10°C / min. At this time, a magnetic field parallel to the width direction of the amorphous ribbon is applied with a magnetic field strength of 1500Gs. The magnetic field heat treatment is carried out at this temperature and magnetic field for 90 minutes. The core is then cooled to room temperature with the furnace to obtain the magnetic core.

[0037] Examples 2-12 and Comparative Examples 1-4

[0038] The only difference between Examples 2-12, Comparative Examples 1-4 and Example 1 is that in steps (1)-(3), the heating rate or temperature or pressure of the first heat treatment, the heating rate or temperature or pressure of the second heat treatment, the temperature or magnetic field strength and time of the magnetic field heat treatment are as detailed in Table 1.

[0039] Example 13

[0040] The only difference between this embodiment and Embodiment 1 is that in step (1), the alloy is Fe. 73.5 Si 15.5 B7Cu1Nb3 amorphous ribbon.

[0041] Table 1

[0042] The magnetic cores prepared above were subjected to performance tests: the inductance L of the magnetic core was measured using a Keysight Agilent 4294A precision impedance analyzer under an applied magnetic field of 1 A / m and a frequency range of 1 kHz to 100 kHz; the effective permeability μ was measured. e It can be obtained through the inductance L conversion formula:

[0043] μ e = (L×L) e ) / (N 2 ×A e ),

[0044] Where L is the core inductance, μ e L is the effective permeability of the magnetic core. e Let A be the magnetic circuit length of the magnetic core. e Where is the effective cross-sectional area of ​​the magnetic core, and N is the number of coil turns (test condition is 1 turn). The test results are shown in Table 2.

[0045] Using conventional heat treatment processes, such as the preparation method in Comparative Example 5, and taking the magnetic core prepared in Comparative Example 5 as a basis for comparison, the rate of change X of the magnetic permeability of the magnetic cores in other embodiments of the present invention and Comparative Example 5 using conventional heat treatment processes is calculated: X f =(μ n -μ 对比例5 ) / μ 对比例5 *100%, where μ n The effective permeability (μ) of a magnetic core fabricated in a specific embodiment or comparative example at frequency f. 对比例5 The effective permeability of the magnetic core obtained in Comparative Example 5 at frequency f is shown in Table 2.

[0046] Table 2

[0047] As demonstrated in Examples 1-12 and Comparative Examples 1-4, the method of the present invention effectively solves the problems of uneven nucleation and excessive growth of nanocrystals in conventional heat treatment, improving permeability across the entire frequency band from 1 to 100 kHz. Specifically, in the above examples, the permeability of the magnetic core is 160,000-250,000 at 1 kHz, 140,000-200,000 at 10 kHz, and 35,000-40,000 at 100 kHz. Furthermore, it can be observed that, compared to Comparative Example 5, Examples 1-12 show an effective permeability increase of more than 100% at 1 kHz, 10 kHz, and 100 kHz, respectively, confirming that the preparation method of the present invention can significantly improve permeability across the entire frequency band from 1 to 100 kHz using the entire amorphous magnetic tape as raw material through a heat treatment process at specific temperatures and pressures.

[0048] Analysis of Figures 2 and 4-5 reveals that conventional heat treatment often results in uneven heating, leading to inhomogeneous nucleation of nanocrystals, incomplete precipitation, and excessive growth. Therefore, this invention employs a first heat treatment to ensure uniform heating of the amorphous magnetic core, laying the foundation for a second heat treatment. The temperature is then increased to the second heat treatment temperature, with continued pressure increase. A slow heating rate and appropriate holding time ensure sufficient time for grain precipitation at higher temperatures, allowing for slow and uniform growth under pressure. This avoids uneven heating due to overheating, incomplete precipitation due to insufficient holding time, or excessive grain growth due to excessive holding time. Finally, a magnetic field heat treatment is combined to completely orient the nanocrystals. The combined force field and magnetic field heat treatments ensure complete and uniform grain precipitation in the magnetic core, achieving an increase in the core's permeability across the entire frequency range.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a magnetic core, characterized in that, Includes the following steps: (1) The amorphous magnetic core is subjected to a first heat treatment and a second heat treatment in sequence. After cooling and depressurization, a pre-burnt magnetic core is obtained. The temperature of the first heat treatment is 400-480℃, the temperature of the second heat treatment is 490-540℃, the pressure of the first heat treatment is 50-100MPa, and the pressure of the second heat treatment is 90-160MPa. (2) The pre-burnt magnetic core is subjected to magnetic field heat treatment and then cooled to obtain the magnetic core.

2. The method for preparing a magnetic core as described in claim 1, characterized in that, In step (1), the duration of the first heat treatment is 70-180 min, and the heating rate of the first heat treatment is 1-30℃ / min.

3. The method for preparing the magnetic core as described in claim 1, characterized in that, In step (1), the second heat treatment lasts for 70-180 min, the heating rate for the second heat treatment is 1-5 °C / min, and the cooling rate is 5-200 °C / min.

4. The method for preparing a magnetic core as described in claim 1, characterized in that, In step (1), the pressurization method of the first heat treatment and the second heat treatment is selected from at least one of pressurization by inert gas pressure and pressurization by die extrusion; in step (1), the amorphous magnetic core is wound from amorphous strip, and the magnetic field direction of the magnetic field heat treatment in step (2) is parallel to the width direction of the amorphous magnetic core.

5. The method for preparing a magnetic core as described in claim 1, characterized in that, In step (1), the amorphous magnetic core comprises the following elements in atomic percentage: Fe 60-80%, Si 10-20%, B 0-10%, Cu 0-3%, Nb 0-5%, Ni 0-15%, Co 0-10%, and V 0-10%.

6. The method for preparing a magnetic core as described in claim 1, characterized in that, In step (2), the temperature of the magnetic field heat treatment is 460-530℃, the time of the magnetic field heat treatment is 10-180min, and the magnetic field strength of the magnetic field heat treatment is 800-3000Gs.

7. The method for preparing a magnetic core as described in claim 1, characterized in that, In step (1), the cooling and depressurization method is to first cool the system naturally to below 200°C, and then release the system pressure to atmospheric pressure; in step (2), the cooling method is natural cooling.

8. A magnetic core prepared by the method of any one of claims 1-7.

9. The magnetic core as described in claim 8, characterized in that, At a frequency of 1 kHz, the permeability of the magnetic core is 160,000-250,000; at 10 kHz, the permeability of the magnetic core is 140,000-200,000; and at 100 kHz, the permeability of the magnetic core is 35,000-44,000.

10. The application of the magnetic core according to claim 8 or 9 in the manufacture of new energy vehicles, photovoltaic energy storage equipment, electronic camera equipment, and 5G communication equipment.

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