A high-permeability low-loss nanocrystalline composite magnetic powder core and a preparation method thereof

Abstract

The application provides a high-permeability low-loss iron-based nanocrystalline magnetic powder core and a preparation method thereof. The preparation method of the nanocrystalline magnetic powder core comprises the following steps: dispersing a resin bonding agent in acetone, adding an iron-based amorphous powder, and stirring until the acetone is completely volatilized; adding a release agent after granulation and drying, and obtaining an amorphous magnetic powder core after pressing and curing; the molecular formula of the iron-based amorphous powder is Fe a Si b B c Cu d Nb e M f M is a combination of two or three of metal elements Mn, V and C; and the obtained amorphous magnetic powder core is subjected to vacuum annealing treatment to obtain a nanocrystalline magnetic powder core. The obtained iron-based nanocrystalline magnetic powder core can simultaneously improve the permeability and reduce the loss by optimizing the components, and the comprehensive performance is improved; the optimized components can improve the stability and reliability of the magnetic powder core, so that the magnetic performance of the magnetic powder core can be maintained stable in a long-term use process.

Description

Technical Field

[0001] This invention relates to a high-permeability, low-loss nanocrystalline composite magnetic powder core and its preparation method, belonging to the field of magnetic materials technology. Background Technology

[0002] In today's technology-driven era, the rapid development of energy conversion and power electronics technologies has led to an unprecedented surge in demand for high-performance magnetic materials. From efficient motor drive systems in electric vehicles to high-frequency power conversion modules in 5G communication base stations, every key application scenario places stringent requirements on magnetic core materials. These requirements not only drive industry development but also prompt the search for higher-quality magnetic powder core materials to meet the needs of emerging industries.

[0003] Nanocrystalline magnetic powder cores, as a high-performance soft magnetic composite material, have attracted much attention due to their unique magnetic properties and broad application prospects. This material is formed by mixing and pressing ferromagnetic powder with an insulating medium, and possesses numerous advantages, such as suppressing eddy currents, improving frequency stability, and broadening its application range. Therefore, improving the permeability and reducing the loss of nanocrystalline magnetic powder cores is crucial to meeting the demands of modern technological development for high-performance magnetic materials.

[0004] While existing methods such as optimizing preparation processes and powder coating technologies each have their advantages, they also have significant limitations. For example, increasing molding pressure is an effective way to improve magnetic permeability, but excessive pressure can cause mold scratches, reduce mold life, and potentially increase internal stress in the magnetic powder core, affecting magnetic properties. Adding a certain amount of insulating agent can effectively reduce the loss of the magnetic powder core, but it also leads to a decrease in magnetic permeability. Composition improvement, as another method, has unique advantages in improving the magnetic permeability and reducing losses of nanocrystalline magnetic powder cores: by adjusting the chemical composition of the ferromagnetic powder, its magnetic properties, such as magnetic permeability, coercivity, and loss, can be precisely controlled. This precision is difficult to achieve with other methods; composition design not only focuses on improving individual performance indicators but also considers the balance of multiple performance indicators.

[0005] Therefore, it is of great significance to optimize the composition to obtain an iron-based nanocrystalline magnetic powder core with high permeability and low loss, as well as excellent stability and reliability, which can maintain stable magnetic properties during long-term use. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a high-permeability, low-loss iron-based nanocrystalline magnetic powder core and its preparation method. By optimizing the composition, this invention achieves a simultaneous increase in permeability and reduction in loss in the resulting iron-based nanocrystalline magnetic powder core, thus enhancing overall performance. Furthermore, the optimized composition improves the stability and reliability of the magnetic powder core, ensuring stable magnetic properties during long-term use.

[0007] The technical solution of the present invention is as follows:

[0008] A method for preparing a high-permeability, low-loss iron-based nanocrystalline magnetic powder core includes the following steps:

[0009] (1) The resin adhesive is dispersed in acetone, and iron-based amorphous powder is added. The mixture is stirred until the acetone is completely evaporated. After granulation and drying, a release agent is added, and the mixture is pressed and cured to obtain an amorphous magnetic powder core. The molecular formula of the iron-based amorphous powder is Fe. a Si b B c Cu d Nb e M f M is a combination of two or three of the metallic elements Mn, V, and C, where a, b, c, d, e, and f are the atomic percentages of the corresponding elements, a+b+c+d+e+f=100, 73≤a≤74, 12.5≤b≤14, 7.5≤c≤9, 0.5≤d≤1, 2≤e≤3, and 2.5≤f≤4.

[0010] (2) The amorphous magnetic powder core obtained in step (1) is subjected to vacuum annealing to obtain nanocrystalline magnetic powder core.

[0011] According to the present invention, the iron-based amorphous powder in step (1) is prepared by weighing each element raw material according to atomic percentage, adding the raw material to a melting furnace and melting it uniformly to obtain a molten liquid; the molten liquid is then subjected to water-air combined atomization to obtain spherical amorphous powder. The raw material for Fe element is Fe elemental, FeB alloy, FeNb alloy and FeC alloy, the raw material for elements Si, Cu, Mn and V is the corresponding elemental, the raw material for element B is FeB alloy, the raw material for element Nb is FeNb alloy and the raw material for element C is FeC alloy; preferably, the iron-based amorphous powder is prepared according to the following method:

[0012] (I) Weigh the raw materials Fe element, Si element, FeB alloy, FeNb alloy, Cu element and V element according to atomic percentage and place them in the melting furnace. After the raw materials are put in, turn on the high-purity argon gas.

[0013] (II) Turn on the vacuum pump until the furnace pressure is less than 10 Pa, introduce high-purity argon as a protective gas until the furnace pressure is 101 kPa, heat to 1250-1350℃ to melt, and hold for 20-30 min; then add Mn and FeC alloy according to atomic percentage, and hold at 1250-1350℃ for 20-30 min to obtain the molten liquid.

[0014] (III) The molten liquid obtained in step (II) is subjected to water-air combined atomization and sieving to obtain iron-based amorphous powder.

[0015] Preferably, in step (I), FeNb alloy, elemental V and part of elemental Fe are placed at the bottom of the melting crucible; elemental Si and FeB alloy are placed in the middle part, and elemental Cu and the remaining elemental Fe are placed at the top, wherein the mass ratio of elemental Fe at the top and bottom is 2 to 3:1.

[0016] Preferably, the water-gas combined atomization step in step (III) involves feeding the molten liquid into an atomization device, where water and gas act as atomizing media to break the molten liquid into fine metal droplets. After cooling, iron-based amorphous powder treated by water-gas combined atomization is obtained. The diameter of the leak in the water-gas combined atomization is 4.0–5.0 mm, the atomizing water pressure is 50–60 MPa, the atomizing gas pressure is 1–2 MPa, and the gas is N2 or Ar2.

[0017] Preferably, the particle size D50 of the iron-based amorphous powder obtained after sieving in step (III) is 15-25 μm.

[0018] According to a preferred embodiment of the present invention, the resin adhesive in step (1) is at least one of epoxy resin, phenolic resin, and silicone resin; the mass ratio of the resin adhesive to the volume of acetone is 1g:5-15mL.

[0019] According to a preferred embodiment of the present invention, the mass of the resin adhesive in step (1) is 2% to 4% of the mass of the iron-based amorphous powder.

[0020] According to a preferred embodiment of the present invention, the granulation step in step (1) is granulation through a 60-70 mesh sieve; the drying temperature is 50-60°C and the drying time is 50-80 min.

[0021] According to a preferred embodiment of the present invention, the release agent in step (1) is zinc stearate, and the mass of the release agent is 0.3 to 0.8% of the mass of the iron-based amorphous powder.

[0022] According to a preferred embodiment of the present invention, the pressing in step (1) specifically involves pressing at 1200-1400 MPa for a holding time of 10 seconds.

[0023] According to a preferred embodiment of the present invention, the curing temperature in step (1) is 150-200°C and the curing time is 60-80 min.

[0024] According to a preferred embodiment of the present invention, the vacuum annealing step in step (2) is as follows: holding at 5-10 Pa for 60-80 min, holding at 490-570 °C, heating at a rate of 2-4 °C / min, and then cooling with the furnace.

[0025] The technical features and beneficial effects of this invention are as follows:

[0026] This invention optimizes the alloy composition by adding large-atomic-radius transition metal elements Mn and V, as well as the non-metallic element C. This increases the mixing enthalpy and atomic mismatch ratio among the alloy elements, which helps improve the alloy's thermal stability and amorphous formation ability. The amorphous rate of the water-air co-atomized powder is increased by 5%-10%. Simultaneously, the addition of Mn and V helps inhibit grain growth, resulting in finer nanocrystalline grains after annealing, thus achieving an excellent balance between high permeability and low loss. Furthermore, this invention, through optimized alloy composition and conventional insulating coating processes, achieves improved performance of the magnetic powder core. Compared with methods such as optimizing the preparation process and powder coating technology, it can balance multiple performance aspects. Moreover, the optimized composition enhances the stability and reliability of the magnetic powder core, ensuring stable magnetic properties during long-term use. Attached Figure Description

[0027] Figure 1 This is a graph showing the laser particle size analysis data of the iron-based amorphous powder obtained in Example 1.

[0028] Figure 2 The image shows the XRD pattern of the iron-based amorphous powder obtained in Example 1.

[0029] Figure 3 The effective magnetic permeability curves of the nanocrystalline magnetic powder cores prepared in Examples 1-2 and Comparative Examples 1-2 are shown.

[0030] Figure 4 The loss curves are for the nanocrystalline magnetic powder cores prepared in Examples 1-2 and Comparative Examples 1-2. Detailed Implementation

[0031] The present invention will be further described below with reference to specific embodiments and accompanying drawings, but these are not intended to limit the scope of protection of the present invention.

[0032] All materials used in the embodiments are conventional materials that are available on the market, and all methods described are existing technologies unless otherwise specified.

[0033] Example 1

[0034] A method for preparing a high-permeability, low-loss iron-based nanocrystalline magnetic powder core includes the following steps:

[0035] (a) The molecular formula of iron-based amorphous powder is Fe 73 Si 12.5 B8Cu1Nb2Mn1V 1.5 C1, the specific preparation method is as follows:

[0036] (1) The raw materials are proportioned according to the atomic percentage of each element. The raw materials for Fe are Fe elemental substance, FeB alloy, FeNb alloy and FeC alloy. The raw materials for Si, Cu, Mn and V are the elemental substances of the corresponding elements. The raw material for B is FeB alloy (B content is 17.84 wt.%). The raw material for Nb is FeNb alloy (Nb content is 65% wt.%). The raw material for C is FeC alloy (C content is 5% wt.%).

[0037] (2) Place the raw materials in an induction melting furnace, with the high-melting-point FeNb alloy, V element and part of Fe element laid at the bottom of the melting crucible; Si element and FeB alloy placed in the middle part for easy induction heating; Cu element and the remaining Fe element placed at the top (the mass ratio of Fe element at the top and bottom is 2:1). The vacuum pump is turned on until the furnace pressure is less than 10 Pa. High-purity argon is introduced as a protective gas until the furnace pressure reaches 101 kPa. The heat-preserving crucible and the melting crucible are heated and held at 1350℃ for 30 min. After the raw materials are completely melted, the volatile Mn element and FeC alloy are added to the melt through the feeding funnel. After the Mn and FeC alloy are completely melted, the heat is held at 1350℃ for 30 min to mix the raw materials evenly and obtain the molten liquid. The molten liquid is poured into the atomization equipment using the heat-preserving crucible. After water-gas combined atomization (nozzle diameter 4.0 mm, atomizing water pressure 50 MPa, atomizing gas pressure 1 MPa, gas is Ar2) and sieving, iron-based amorphous powder is obtained.

[0038] The laser particle size analysis data and XRD pattern of the obtained iron-based amorphous powder are shown in the figure below. Figure 1 , Figure 2 As shown in the figure, the sieved amorphous magnetic powder has a D50 of 16.8 μm and exhibits a completely amorphous state.

[0039] (II) The preparation steps of the nanocrystalline magnetic powder core are as follows:

[0040] (1) Insulation coating: 2g of silicone resin (REN60, Zhongshan Kebang Chemical Materials Technology Co., Ltd.) and 1g of epoxy resin (ZY6267A, Shenzhen Ziyu Technology Co., Ltd.) were dispersed in 30mL of acetone, and 100g of the above iron-based amorphous powder was added. The mixture was stirred at 300rpm for 30min until the acetone was completely evaporated. The mixture was then granulated through a 65-mesh sieve and dried at 60℃ for 60min.

[0041] (2) Adding lubricant: Add zinc stearate to the dried powder to obtain a mixed powder, wherein the mass of zinc stearate is 0.5% of the mass of the iron-based amorphous powder.

[0042] (3) Cold pressing: The mixed powder is pressed in a mold (pressure of 1400MPa, holding time of 10s), and then cured at 150℃ for 60min. The size of the formed magnetic powder core is 25.5×16×4.5mm.

[0043] (4) Vacuum annealing: The formed magnetic powder core is crystallized and annealed in a vacuum annealing furnace, where the vacuum degree is 5 Pa, the holding temperature is 530℃, the heating rate is 4℃ / min, and after the holding is completed, it is cooled to room temperature with the furnace.

[0044] The permeability of the magnetic powder core was tested using an LCR-8210 digital bridge at 1V and 1MHz. Losses were measured using a soft magnetic AC measuring instrument (MAST-3000SA) manufactured by Hunan Lianzhong. The test results are as follows: Figure 3 , Figure 4 .

[0045] Example 2

[0046] A method for preparing a high-permeability, low-loss iron-based nanocrystalline magnetic powder core is described in Example 1, except that the molecular formula of the iron-based amorphous powder is Fe. 73 Si 13 B8Cu1Nb 2.5 Mn 1.5 C1 is prepared using the same method as in Example 1.

[0047] The permeability of the magnetic powder core was tested using an LCR-8210 digital bridge at 1V and 1MHz. Losses were measured using a soft magnetic AC measuring instrument (MAST-3000SA) manufactured by Hunan Lianzhong. The test results are as follows. Figure 3 , Figure 4 .

[0048] Comparative Example 1

[0049] A method for preparing a high-permeability, low-loss iron-based nanocrystalline magnetic powder core is described in Example 1, except that the molecular formula of the iron-based amorphous powder is Fe. 73.5 Si 13.5 B9Cu1Nb3 was prepared using the same method as in Example 1.

[0050] The permeability of the magnetic powder core was tested using an LCR-8210 digital bridge at 1V and 1MHz. Losses were measured using a soft magnetic AC measuring instrument (MAST-3000SA) manufactured by Hunan Lianzhong. The test results are as follows. Figure 3 , Figure 4 .

[0051] Comparative Example 2

[0052] A method for preparing a high-permeability, low-loss iron-based nanocrystalline magnetic powder core is described in Example 1, except that the molecular formula of the iron-based amorphous powder is Fe. 73.5 Si 13.5 B8Cu1Nb3C1 was prepared using the same method as in Example 1.

[0053] The permeability of the magnetic powder core was tested using an LCR-8210 digital bridge at 1V and 1MHz. Losses were measured using a soft magnetic AC measuring instrument (MAST-3000SA) manufactured by Hunan Lianzhong. The test results are as follows. Figure 3 , Figure 4 .

[0054] Table 1 Performance comparison of Examples 1-2 and Comparative Examples 1-2

[0055]

[0056] In summary, based on Table 1 and... Figure 1-4 The results show that the addition of Mn, V, and C elements has a significant impact on the soft magnetic properties of the material in the alloy system of this invention. Compared with Comparative Example 1, the magnetic powder cores prepared in Examples 1 and 2 have higher permeability and their losses remain at a lower level at different frequencies compared to Comparative Example 1, resulting in excellent overall soft magnetic properties. Among them, Example 1 has the best performance, indicating that the combined effect of Mn, V, and C can effectively optimize the soft magnetic properties of the material. When the combination of Mn and C is added in Example 2, although the performance is slightly different from that of Example 1, it is still better than Comparative Example 1, indicating that the combination of Mn and C also has a certain performance improvement effect. However, when only C element is added in Comparative Example 2, the high-frequency permeability is relatively low and the loss is high. Its soft magnetic properties are significantly worse than those of the examples with the combination of Mn, V, and C or the combination of Mn and C, further confirming the importance of Mn and V in improving the soft magnetic properties of the material. It can be seen that the specific element combination involved in this invention has a unique and irreplaceable role in improving the soft magnetic properties of the alloy and reducing losses.

[0057] Under the same preparation process, compared with Comparative Example 1, Example 1, through compositional improvements, increased the magnetic permeability (100kHz) of the prepared magnetic powder core by more than 20%, and the amorphous rate of the water-air co-atomized powder reached 100%, which is beneficial for industrial production. Simultaneously, this invention improves the overall soft magnetic properties of the original magnetic powder through compositional design. The preparation process only uses conventional organic coating, eliminating the need for passivation or other powder coating technologies. The process is simple, exhibiting higher stability and reliability, which is beneficial for industrial production and commercial applications.

[0058] The above description is merely a preferred embodiment of this application and is not intended to limit the application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications and improvements made within the scope of the principles of this invention should be included within the protection scope of this invention.

Claims

1. A method for preparing a high-permeability, low-loss iron-based nanocrystalline magnetic powder core, comprising the following steps: (1) The resin adhesive is dispersed in acetone, and iron-based amorphous powder is added. The mixture is stirred until the acetone is completely evaporated. After granulation and drying, a release agent is added, and the mixture is pressed and cured to obtain an amorphous magnetic powder core. The molecular formula of the iron-based amorphous powder is Fe. a Si b B c Cu d Nb e M f M is a combination of two or three of the metallic elements Mn, V, and C, where, a, b, c, d, e, and f are the atomic percentages of the corresponding elements, a + b + c + d + e + f = 100, 73 ≤ a ≤ 74, 12.5 ≤ b ≤ 14, 7.5 ≤ c ≤ 9, 0.5 ≤ d ≤ 1, 2 ≤ e ≤ 3, and 2.5 ≤ f ≤ 4. (2) The amorphous magnetic powder core obtained in step (1) is subjected to vacuum annealing to obtain nanocrystalline magnetic powder core.

2. The method for preparing a high-permeability, low-loss iron-based nanocrystalline magnetic powder core according to claim 1, characterized in that, The iron-based amorphous powder mentioned in step (1) is prepared by weighing each element raw material according to atomic percentage, adding the raw material to a melting furnace and melting it evenly to obtain a molten liquid; the molten liquid is then subjected to water-air combined atomization to obtain powder; the raw material for the Fe element is Fe elemental substance, FeB alloy, FeNb alloy and FeC alloy, the raw material for the elements Si, Cu, Mn and V is the corresponding elemental substance, the raw material for the element B is FeB alloy, the raw material for the element Nb is FeNb alloy and the raw material for the element C is FeC alloy.

3. The method for preparing a high-permeability, low-loss iron-based nanocrystalline magnetic powder core according to claim 2, characterized in that, The iron-based amorphous powder was prepared according to the following method: (I) Weigh the raw materials Fe element, Si element, FeB alloy, FeNb alloy, Cu element and V element according to atomic percentage and place them in the melting furnace. After the raw materials are put in, turn on the high-purity argon gas. (II) Turn on the vacuum pump until the furnace pressure is less than 10 Pa, introduce high-purity argon as a protective gas until the furnace pressure is 101 kPa, heat to 1250-1350℃ to melt, and hold for 20-30 min; then add Mn and FeC alloy according to atomic percentage, and hold at 1250-1350℃ for 20-30 min to obtain the molten liquid. (III) The molten liquid obtained in step (II) is subjected to water-air combined atomization and sieving to obtain iron-based amorphous powder.

4. The method for preparing a high-permeability, low-loss iron-based nanocrystalline magnetic powder core according to claim 3, characterized in that, In step (I), FeNb alloy, V element and part of Fe element are placed at the bottom of the melting crucible; Si element and FeB alloy are placed in the middle part, and Cu element and the remaining Fe element are placed at the top, wherein the mass ratio of Fe element at the top and bottom is 2 to 3:

1.

5. The method for preparing a high-permeability, low-loss iron-based nanocrystalline magnetic powder core according to claim 3, characterized in that, In step (III), the diameter of the leak in the water-air combined atomization is 4.0-5.0 mm, the atomizing water pressure is 50-60 MPa, the atomizing gas pressure is 1-2 MPa, and the gas is N2 or Ar2. After sieving, the particle size D50 of the iron-based amorphous powder obtained is 15-25 μm.

6. The method for preparing a high-permeability, low-loss iron-based nanocrystalline magnetic powder core according to claim 1, characterized in that, The resin adhesive mentioned in step (1) is at least one of epoxy resin, phenolic resin, and silicone resin; the mass ratio of the resin adhesive to the volume of acetone is 1g:5-15mL; the mass of the resin adhesive is 2% to 4% of the mass of the iron-based amorphous powder.

7. The method for preparing a high-permeability, low-loss iron-based nanocrystalline magnetic powder core according to claim 1, characterized in that, The granulation step in step (1) is granulation through a 60-70 mesh sieve; the drying temperature is 50-60℃ and the drying time is 50-80 min.

8. The method for preparing a high-permeability, low-loss iron-based nanocrystalline magnetic powder core according to claim 1, characterized in that, The release agent mentioned in step (1) is zinc stearate, and the mass of the release agent is 0.3 to 0.8% of the mass of the iron-based amorphous powder.

9. The method for preparing a high-permeability, low-loss iron-based nanocrystalline magnetic powder core according to claim 1, characterized in that, The pressing in step (1) specifically involves pressing at 1200-1400 MPa for 10 seconds; the curing temperature is 150-200°C and the curing time is 60-80 minutes.

10. The method for preparing a high-permeability, low-loss iron-based nanocrystalline magnetic powder core according to claim 1, characterized in that, The vacuum annealing step in step (2) is as follows: hold at 5-10 Pa for 60-80 min, the holding temperature is 490-570℃, the heating rate is 2-4℃ / min, and then cool with the furnace.

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