Iron-based soft magnetic powder core based on multi-particle-size distribution and preparation method of iron-based soft magnetic powder core

Abstract

The invention discloses an iron-based soft magnetic powder core based on multi-particle-size distribution and a preparation method of the iron-based soft magnetic powder core, and belongs to the technical field of magnetic material preparation, and the preparation method comprises the steps that iron-based magnetic powder is subjected to grading treatment to obtain initial iron-based magnetic powder with different particle sizes; the initial iron-based magnetic powder with different particle sizes is annealed, and the annealing conditions are set as follows: in the first stage, the initial iron-based magnetic powder is heated to 195-205 DEG C from the room temperature and subjected to heat preservation for 20-30 min, in the second stage, the initial iron-based magnetic powder is continuously heated to 470-510 DEG C and subjected to heat preservation for 110-120 min, and in the third stage, the initial iron-based magnetic powder is continuously heated to 560-590 DEG C and subjected to heat preservation for 50-60 min; the iron-based soft magnetic powder core based on multi-particle-size distribution is obtained by sequentially carrying out insulation coating, granulation, compression molding and magnet ring curing on the iron-based magnetic powder with different particle sizes subjected to annealing pretreatment. The magnetic performance of the iron-based soft magnetic powder core can be effectively improved, so that the application requirements of various fields such as mold pressing inductors on high-performance magnetic materials are met.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetic material preparation, and in particular relates to an iron-based soft magnetic powder core based on multi-particle size distribution and a preparation method thereof. Background Art

[0002] Iron-based soft magnetic powder cores have the advantages of high saturation magnetic induction intensity, high effective magnetic permeability, low coercive force, etc., and because of their low raw material cost, they have become the preferred raw material reserve for the development of a new generation of electronic power components, and are widely used in many high-end fields such as electronic power, modern communications, electromagnetic compatibility, and current sources. However, the existing iron-based soft magnetic powder cores also have certain limitations, namely, their resistivity is low and their high-frequency magnetic loss is high, making them unable to adapt to the development trend of high frequency, high efficiency and integration, so their magnetic properties need to be further improved.

[0003] At present, the preparation process of iron-based soft magnetic powder core usually includes preparing amorphous strips by melt water quenching, obtaining amorphous magnetic powder by mechanical crushing or gas / water atomization, and then obtaining fine amorphous magnetic powder by classification, which is then organically coated and pressed in sequence, and finally the green magnetic powder core is cured in a vacuum or inert gas environment to obtain an iron-based soft magnetic powder core. However, in this process, the powder obtained by the atomization method has a coarse particle size, generally above 100 μm, and the particle size is uneven, which will affect the performance of the iron-based soft magnetic powder core.

[0004] Annealing is a key step in improving the magnetic properties of magnetic powder cores. It can release the internal stress accumulated inside the magnetic powder core during the pressing process, reduce hysteresis loss, and affect the alloying and crystallization degree of the magnetic powder. For example, the Chinese patent application with publication number CN107578872A provides a method for preparing a metal soft magnetic powder core that is resistant to high temperature heat treatment. Its main focus is on multiple heat treatments of the magnetic powder core formed body, which can only improve the stress state of the formed product. For example, the Chinese patent application with publication number CN107119174A provides an annealing method for improving the DC bias performance of the iron silicon aluminum soft magnetic powder core. The formed magnetic powder core is also placed in a vacuum furnace for annealing to obtain an amorphous magnetic powder core product. These methods can only improve the stress state of the formed product, and none of them consider further refining the grain structure.

[0005] At present, there are relatively few studies on the changes in magnetic properties of magnetic powder after annealing at different temperatures, and annealing at a single temperature often makes the performance of magnetic powder unstable. Therefore, the selection of multi-stage annealing temperature and holding time is particularly important, as they are the key factors affecting the performance of the final iron-based soft magnetic powder core. In order to prepare magnetic powder cores with high magnetic permeability and low loss, it is necessary to deeply explore the influence of multi-stage annealing process on the preparation process of magnetic powder cores. In addition, if the magnetic powder core has a dense internal structure, it will be more conducive to obtaining excellent magnetic properties. Therefore, further research and development of new preparation methods for iron-based soft magnetic powder cores are still needed. Summary of the invention

[0006] In view of the above, the purpose of the present invention is to provide an iron-based soft magnetic powder core based on multiple particle size distribution and a preparation method thereof, to further improve the magnetic properties of the iron-based soft magnetic powder core, to obtain an iron-based soft magnetic powder core based on multiple particle size distribution with high DC bias performance, high magnetic permeability, and low magnetic loss, so as to meet the application requirements of high-performance magnetic materials in various fields such as molded inductors.

[0007] In order to achieve the above-mentioned invention object, the technical solution provided by the present invention is as follows: An embodiment of the present invention provides a method for preparing an iron-based soft magnetic powder core based on a multi-particle size distribution, comprising the following steps: The iron-based magnetic powder is subjected to classification treatment to obtain initial iron-based magnetic powders of different particle sizes. Directly classifying the magnetic powder helps to further increase the density of the magnetic powder core in the subsequent process, thereby improving its magnetic properties.

[0008] The initial iron-based magnetic powders with different particle sizes were annealed separately to obtain annealed pretreated iron-based magnetic powders with different particle sizes. The annealing conditions were set as follows: the first stage of annealing was heated from room temperature to 195~205 ℃ and kept warm for 20~30 min to ensure the temperature uniformity of the annealing furnace and prevent temperature surge; the second stage continued to heat to 470~510 ℃ and kept warm for 110~120 min to increase the nucleation point and reduce the grain size; the third stage continued to heat to 560~590 ℃ and kept warm for 50~60 min to regulate the growth of nanocrystals and optimize the magnetic properties of the final nanocrystalline powder. The initial iron-based magnetic powder in the powder state was directly annealed for three stages, with different temperature settings in each stage, in order to directly regulate the grain size and microstructure from the powder stage, and to precisely control the different stages of grain growth, so as to obtain nanocrystalline powder with uniform particle size distribution, which has high magnetic permeability, low loss and excellent DC bias performance, providing a performance basis for the subsequent preparation of inductor devices.

[0009] The iron-based magnetic powders with different particle sizes that have been annealed and pretreated are subjected to insulation coating, granulation and compression molding, and magnetic ring solidification in sequence to obtain an iron-based soft magnetic powder core based on multi-particle size distribution.

[0010] Preferably, the median particle size D50 of the initial iron-based magnetic powders of different particle sizes after classification is in the range of 10-100 μm.

[0011] Preferably, the composition of the iron-based magnetic powder includes Si: 20-25 wt.%, Nb: 1-5 wt.%, Cu: 0.5-2 wt.%, B: 0-30 wt.%, Fe: 50-75 wt.%.

[0012] Preferably, during the annealing process, the inert atmosphere uses high-purity argon gas, the argon gas flow rate is controlled at 600-1000 ml / min, and the heating rate to reach the annealing temperature is controlled at 15-40 °C / min.

[0013] Preferably, the annealed pretreated iron-based magnetic powders of different particle sizes are sequentially subjected to insulation coating, granulation and compression molding, and magnetic ring solidification to obtain an iron-based soft magnetic powder core based on a multi-particle size distribution, comprising: Insulation coating: mixing the annealed pretreated iron-based magnetic powders of different particle sizes with an organic binder solution and stirring them thoroughly until the solution evaporates to obtain iron-based magnetic powders coated with the organic binder; Granulation and pressing: the iron-based magnetic powder coated with the organic binder is placed in a vacuum drying oven to be dried into an iron-based composite powder, and then the iron-based composite powder is pressed into a magnetic ring blank; Magnetic ring curing: The magnetic ring blank is heated and kept warm in an inert atmosphere to complete the curing process, and then taken out after cooling to room temperature in the furnace to obtain an iron-based soft magnetic powder core with a multi-particle size distribution.

[0014] Preferably, the preparation of the organic binder solution comprises dissolving 2 wt.% of the total weight of the annealed pretreated iron-based magnetic powders of different particle sizes in an organic solvent, wherein the organic binder comprises at least one of epoxy resin, silicone resin, polyimide resin, and phenolic resin, and the organic solvent comprises acetone or anhydrous ethanol. The organic binder is preferably epoxy resin, which can form a good coating insulating layer on the surface of the annealed pretreated iron-based magnetic powder.

[0015] Preferably, the particle size of the iron-based composite powder obtained by granulation is 10-300 μm.

[0016] Preferably, the forming pressure of the compression molding process is 600-1000 MPa, and the packing time is 60-180 s.

[0017] Preferably, when curing the magnetic ring, the temperature is heated to 200°C at a heating rate of 5-10°C / min and kept at this temperature for 60-180 min.

[0018] To achieve the above-mentioned purpose of the invention, an embodiment of the present invention further provides an iron-based soft magnetic powder core based on multiple particle size distribution, which is prepared by adopting the above-mentioned preparation method of the iron-based soft magnetic powder core based on multiple particle size distribution.

[0019] Compared with the prior art, the present invention has the following beneficial effects: The process equipment adopted by the present invention is simple, the process flow is highly controllable, the production cost is low, it is easy to implement, and the preparation cost is low. The obtained nanocrystalline soft magnetic powder has the advantages of nanocrystalline powder, effectively avoids the decomposition of the insulating medium and the destruction of the insulating film, and can obtain higher magnetic permeability and lower loss, as well as excellent soft magnetic properties and mechanical and physical properties. Compared with conventional magnetic powder cores that have not undergone multi-stage annealing treatment and particle size matching, it can adapt to high current application environments and has excellent heat dissipation performance, which can effectively improve the heating problem of soft magnetic powder core components. It is suitable for power electronics and other fields, and can meet the needs of electronic products developing in the direction of high precision, high sensitivity, large capacity, and miniaturization. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 It is a schematic flow chart of a method for preparing an iron-based soft magnetic powder core based on multi-particle size distribution provided by an embodiment of the present invention; Figure 2 These are SEM images of the iron-based soft magnetic powders with D50=30 μm and D50=15 μm prepared after three-stage annealing provided in Example 1 of the present invention, (a) D50=30 μm, (b) D50=15 μm. DETAILED DESCRIPTION

[0022] To make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific implementation methods described herein are only used to explain the present invention and do not limit the scope of protection of the present invention.

[0023] The inventive concept of the present invention is: in view of the problem that the magnetic properties of the iron-based soft magnetic powder core are insufficient due to the unreasonable matching of the annealing process and the grain structure in the prior art, the embodiment of the present invention provides an iron-based soft magnetic powder core based on a multi-particle size distribution and a preparation method thereof. On the one hand, it is considered to directly anneal and pre-treat the original magnetic powder obtained by the atomization method and the grading treatment to improve the grain density of the magnetic powder core, optimize the nanocrystalline growth process, and improve its magnetic properties. On the other hand, it is considered to optimize the annealing process, optimize the amorphous powder crystallization process through a three-stage annealing pretreatment, accurately control the different stages of grain growth, and then obtain an iron-based soft magnetic powder core with high magnetic permeability, low loss and excellent DC bias performance through granulation, insulation coating, pressing and curing treatment, which provides a performance basis for the subsequent preparation of inductor devices.

[0024] Figure 1 FIG. 1 is a schematic flow chart of a method for preparing an iron-based soft magnetic powder core based on a multi-particle size distribution provided by an embodiment of the present invention. Figure 1 As shown, the embodiment provides a method for preparing an iron-based soft magnetic powder core based on a multi-particle size distribution, comprising the following steps: S1, preparation of magnetic powder: the iron-based magnetic powder prepared by the gas atomization method is subjected to classification treatment to obtain initial iron-based magnetic powders with different particle sizes.

[0025] S2, magnetic powder annealing: the initial iron-based magnetic powders of different particle sizes were annealed in an inert atmosphere to obtain annealed pretreated iron-based magnetic powders of different particle sizes. The annealing conditions were set as follows: the first stage was heated from room temperature to 195~205 ℃ and kept warm for 20~30 min, the second stage continued to heat to 470~510 ℃ and kept warm for 110~120 min, and the third stage continued to heat to 560~590 ℃ and kept warm for 50~60 min.

[0026] S3, insulation coating: mixing the annealed pretreated iron-based magnetic powders of different particle sizes with an organic binder solution and stirring them fully until the solution evaporates to obtain iron-based magnetic powders coated with the organic binder.

[0027] S4, granulation and pressing: placing the iron-based magnetic powder coated with the organic binder in a vacuum drying oven to dry it into an iron-based composite powder, and then pressing the iron-based composite powder into a magnetic ring blank.

[0028] S5, magnetic ring curing: the magnetic ring blank is heated and kept warm in an inert atmosphere to complete the curing treatment, and is taken out after cooling to room temperature in the furnace to obtain an iron-based soft magnetic powder core with a multi-particle size distribution.

[0029] Example 1

[0030] The method for preparing an iron-based soft magnetic powder core with a multi-particle size distribution in this embodiment specifically comprises the following steps: S1, preparation of magnetic powder: the iron-based magnetic powder prepared by the aerosolization method was classified into four particle sizes of -30 μm, +30 μm, -15 μm, and +15 μm, and was evenly mixed in a ratio of -30 μm to +30 μm of 1:1, and -15 μm to +15 μm of 1:1, to obtain initial iron-based magnetic powders with two particle sizes of D50=30 μm and D50=15 μm.

[0031] S2, magnetic powder annealing: the initial iron-based magnetic powder obtained in step S1 is placed in a vacuum tube annealing furnace and annealed in a flowing argon (purity ≥ 99.9 vol.%) atmosphere. In the first stage, it is heated from room temperature to 200 °C and kept warm for 30 minutes; in the second stage, it is continued to heat to 470 °C and kept warm for 120 minutes; in the third stage, it is continued to heat to 570 °C and kept warm for 60 minutes. The program stops and the annealing ends. After the sample is cooled to room temperature with the furnace, it is taken out to obtain the iron-based magnetic powder with D50 = 30 μm after annealing pretreatment (its SEM results are shown in FIG. Figure 2 (a) in the figure) and iron-based magnetic powder with D50=15 μm (the SEM results are shown in Figure 2 (as shown in (b) in the figure).

[0032] S3, insulation coating: fully dissolve a certain mass fraction of an organic binder in an acetone solution to obtain an organic binder solution, and add the two iron-based magnetic powders with D50=30 μm and D50=15 μm obtained after annealing pretreatment in step S2 into the organic binder solution at a mass ratio of 9:1, and continue stirring to form a coating layer evenly on the surface of the iron-based magnetic powder until the acetone solution is completely volatilized to obtain an iron-based magnetic powder coated with an organic binder.

[0033] S4, granulation and pressing: the iron-based magnetic powder coated with the organic binder obtained in step S3 is placed in a vacuum drying oven and dried at a temperature of 80°C to obtain an iron-based composite powder, which is then pressed to obtain a magnetic ring blank.

[0034] S5, magnetic ring curing: the magnetic ring blank obtained in step S4 is heated from room temperature to 200°C at a heating rate of 10°C / min under an argon protective atmosphere, and kept warm for 60 min. The program is stopped and the curing is completed. The sample is taken out after cooling to room temperature with the furnace to obtain an iron-based soft magnetic powder core with a multi-particle size distribution.

[0035] Example 2

[0036] The method for preparing an iron-based soft magnetic powder core with a multi-particle size distribution in this embodiment specifically comprises the following steps: S1, preparation of magnetic powder: the iron-based magnetic powder prepared by the aerosolization method was classified into four particle sizes of -30 μm, +30 μm, -15 μm, and +15 μm, and was evenly mixed in a ratio of -30 μm to +30 μm of 1:1, and -15 μm to +15 μm of 1:1, to obtain initial iron-based magnetic powders with two particle sizes of D50=30 μm and D50=15 μm.

[0037] S2, magnetic powder annealing: the initial iron-based magnetic powder obtained in step S1 is placed in a vacuum tube annealing furnace and annealed in a flowing argon (purity ≥ 99.9 vol.%) atmosphere. In the first stage, it is heated from room temperature to 200 °C and kept warm for 30 minutes; in the second stage, it is continued to be heated to 470 °C and kept warm for 120 minutes; in the third stage, it is continued to be heated to 580 °C and kept warm for 60 minutes. The program stops and the annealing ends. After the sample is cooled to room temperature with the furnace, it is taken out to obtain the iron-based magnetic powder with D50 = 30 μm and the iron-based magnetic powder with D50 = 15 μm after annealing pretreatment.

[0038] S3, insulation coating: fully dissolve a certain mass fraction of an organic binder in an acetone solution to obtain an organic binder solution, and add the two iron-based magnetic powders with D50=30 μm and D50=15 μm obtained after annealing pretreatment in step S2 in a mass ratio of 1:1 to the organic binder solution, and continue stirring to form a coating layer evenly on the surface of the iron-based magnetic powder until the acetone solution is completely volatilized to obtain an iron-based magnetic powder coated with an organic binder.

[0039] S4, granulation and pressing: the iron-based magnetic powder coated with the organic binder obtained in step S3 is placed in a vacuum drying oven and dried at a temperature of 80°C to obtain an iron-based composite powder, which is then pressed to obtain a magnetic ring blank.

[0040] S5, magnetic ring curing: the magnetic ring blank obtained in step S4 is heated from room temperature to 200°C at a heating rate of 10°C / min under an argon protective atmosphere, and kept warm for 60 min. The program is stopped and the curing is completed. The sample is taken out after cooling to room temperature with the furnace to obtain an iron-based soft magnetic powder core with a multi-particle size distribution.

[0041] Example 3

[0042] The method for preparing an iron-based soft magnetic powder core with a multi-particle size distribution in this embodiment specifically comprises the following steps: S1, preparation of magnetic powder: the iron-based magnetic powder prepared by the aerosolization method was classified into four particle sizes of -30 μm, +30 μm, -15 μm, and +15 μm, and was evenly mixed in a ratio of -30 μm to +30 μm of 1:1, and -15 μm to +15 μm of 1:1, to obtain initial iron-based magnetic powders with two particle sizes of D50=30 μm and D50=15 μm.

[0043] S2, magnetic powder annealing: the initial iron-based magnetic powder obtained in step S1 is placed in a vacuum tube annealing furnace and annealed in a flowing argon (purity ≥ 99.9 vol.%) atmosphere. In the first stage, it is heated from room temperature to 200 °C and kept warm for 30 minutes; in the second stage, it is continued to be heated to 480 °C and kept warm for 120 minutes; in the third stage, it is continued to be heated to 570 °C and kept warm for 60 minutes. The program stops and the annealing ends. After the sample is cooled to room temperature with the furnace, it is taken out to obtain the iron-based magnetic powder with D50 = 30 μm and the iron-based magnetic powder with D50 = 15 μm after annealing pretreatment.

[0044] S3, insulation coating: fully dissolve a certain mass fraction of an organic binder in an acetone solution to obtain an organic binder solution, and add the two iron-based magnetic powders with D50=30 μm and D50=15 μm obtained after annealing pretreatment in step S2 into the organic binder solution at a mass ratio of 1:9, and continue stirring to form a coating layer evenly on the surface of the iron-based magnetic powder until the acetone solution is completely volatilized to obtain an iron-based magnetic powder coated with an organic binder.

[0045] S4, granulation and pressing: the iron-based magnetic powder coated with the organic binder obtained in step S3 is placed in a vacuum drying oven and dried at a temperature of 80°C to obtain an iron-based composite powder, which is then pressed to obtain a magnetic ring blank.

[0046] S5, magnetic ring curing: the magnetic ring blank obtained in step S4 is heated from room temperature to 200°C at a heating rate of 10°C / min under an argon protective atmosphere, and kept warm for 60 min. The program is stopped and the curing is completed. The sample is taken out after cooling to room temperature with the furnace to obtain an iron-based soft magnetic powder core with a multi-particle size distribution.

[0047] Comparative Example 1 In this comparative example, the preparation method of the iron-based soft magnetic powder core is the same as that of Example 1, except that: this comparative example is a one-stage annealing process, and the one-stage annealing process is to heat the initial iron-based magnetic powders of two particle sizes of D50=30 μm and D50=15 μm in a vacuum tube annealing furnace, respectively, from room temperature to 570°C in a flowing argon (purity ≥99.9 vol.%) atmosphere, and keep warm for 60 minutes for annealing to obtain annealed pretreated iron-based magnetic powders with D50=30 μm and iron-based magnetic powders with D50=15 μm, respectively.

[0048] Comparative Example 2 In this comparative example, the preparation method of the iron-based soft magnetic powder core is the same as that of Example 1, except that: the three-stage annealing temperature of this comparative example is: in the first stage, heating from room temperature to 200°C and keeping warm for 30 min; in the second stage, continuing to heat to 420°C and keeping warm for 120 min; in the third stage, continuing to heat to 570°C and keeping warm for 60 min.

[0049] Comparative Example 3 In this comparative example, the preparation method of the iron-based soft magnetic powder core is the same as that of Example 1, except that: the three-stage annealing temperature of this comparative example is: in the first stage, heating from room temperature to 200°C and keeping warm for 30 min; in the second stage, continuing to heat to 470°C and keeping warm for 120 min; in the third stage, continuing to heat to 630°C and keeping warm for 60 min.

[0050] Comparative Example 4 The preparation method of an iron-based soft magnetic powder core based on a single particle size distribution in this comparative example specifically comprises the following steps: S1, preparation of magnetic powder: the iron-based magnetic powder prepared by the aerosolization method is classified into two particle sizes of -30 μm and +30 μm, and is evenly mixed in a ratio of -30 μm and +30 μm of 1:1 to obtain an initial iron-based magnetic powder with D50=30 μm.

[0051] S2, magnetic powder annealing: the initial iron-based magnetic powder obtained in step S1 is placed in a vacuum tube annealing furnace and annealed in a flowing argon (purity ≥ 99.9 vol.%) atmosphere. In the first stage, it is heated from room temperature to 200 °C and kept warm for 30 minutes; in the second stage, it is continued to be heated to 470 °C and kept warm for 120 minutes; in the third stage, it is continued to be heated to 570 °C and kept warm for 60 minutes. The program stops and the annealing ends. After the sample is cooled to room temperature with the furnace, it is taken out to obtain the iron-based magnetic powder with D50 = 30 μm pre-annealed.

[0052] S3, insulation coating: fully dissolving a certain mass fraction of an organic binder in an acetone solution to obtain an organic binder solution, and adding the iron-based magnetic powder after annealing pretreatment obtained in step S2 to the organic binder solution, and continuously stirring to form a coating layer evenly on the surface of the iron-based magnetic powder until the acetone solution is completely volatilized to obtain an iron-based magnetic powder coated with the organic binder.

[0053] S4, granulation and pressing: the iron-based magnetic powder coated with the organic binder obtained in step S3 is placed in a vacuum drying oven and dried at a temperature of 80°C to obtain an iron-based composite powder, which is then pressed to obtain a magnetic ring blank.

[0054] S5, magnetic ring curing: the magnetic ring blank obtained in step S4 is heated from room temperature to 200°C at a heating rate of 10°C / min under an argon protective atmosphere, and kept warm for 60 min. The program is stopped and the curing is completed. The sample is taken out after cooling to room temperature with the furnace to obtain an iron-based soft magnetic powder core with a multi-particle size distribution.

[0055] Comparative Example 5 In this comparative example, the preparation method of the iron-based soft magnetic powder core is the same as that of comparative example 4, except that: this comparative example is a one-stage annealing, and the one-stage annealing process is to heat the initial iron-based magnetic powder with D50=30 μm from room temperature to 570°C in a vacuum tube annealing furnace in a flowing argon (purity ≥99.9 vol.%) atmosphere, and keep it warm for 60 min for annealing to obtain an annealed pretreated iron-based magnetic powder with D50=30 μm.

[0056] As shown below, Table 1 compares the magnetic properties of the iron-based soft magnetic powder cores prepared in Examples 1 to 3 of the present invention and Comparative Examples 1 to 5.

[0057] Table 1 Comparison of magnetic properties of iron-based soft magnetic powder cores of Examples 1 to 3 and Comparative Examples 1 to 5

[0058] It can be seen that the soft magnetic powder core prepared by directly performing multi-particle size matching and multi-stage annealing process on the magnetic powder in the embodiment of the present invention has higher DC bias performance, magnetic permeability, and lower magnetic loss.

[0059] The specific implementation methods described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above is only the most preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an iron-based soft magnetic powder core based on multi-particle size distribution, characterized in that: The following steps are involved: The iron-based magnetic powder is subjected to a classification process to obtain initial iron-based magnetic powders of different particle sizes; The initial iron-based magnetic powders with different particle sizes were annealed to obtain annealed pretreated iron-based magnetic powders with different particle sizes. The annealing conditions were set as follows: the first stage was heated from room temperature to 195-205 °C and kept warm for 20-30 min, the second stage was continued to heat to 470-510 °C and kept warm for 110-120 min, and the third stage was continued to heat to 560-590 °C and kept warm for 50-60 min. The iron-based magnetic powders with different particle sizes that have been annealed and pretreated are subjected to insulation coating, granulation and compression molding, and magnetic ring solidification in sequence to obtain an iron-based soft magnetic powder core based on multi-particle size distribution.

2. The method for preparing an iron-based soft magnetic powder core based on multiple particle size distribution according to claim 1, characterized in that: The median particle size D50 of the initial iron-based magnetic powders of different particle sizes after classification treatment ranges from 10 to 100 μm.

3. The method for preparing an iron-based soft magnetic powder core based on multiple particle size distribution according to claim 1, characterized in that: The composition of the iron-based magnetic powder includes Si: 20~25 wt.%, Nb: 1~5 wt.%, Cu: 0.5~2 wt.%, B: 0~30 wt.%, Fe: 50~75 wt.%.

4. The method for preparing an iron-based soft magnetic powder core based on multiple particle size distribution according to claim 1, characterized in that: During the annealing process, high-purity argon gas is used as the inert atmosphere, the argon gas flow rate is controlled at 600~1000 ml / min, and the heating rate to reach the annealing temperature is controlled at 15~40 ℃ / min.

5. The method for preparing an iron-based soft magnetic powder core based on multiple particle size distribution according to claim 1, characterized in that: The annealed pretreated iron-based magnetic powders of different particle sizes are sequentially subjected to insulation coating, granulation and compression molding, and magnetic ring solidification to obtain an iron-based soft magnetic powder core with multiple particle size distribution, including: Insulation coating: mixing the annealed pretreated iron-based magnetic powders of different particle sizes with an organic binder solution and stirring them thoroughly until the solution evaporates to obtain iron-based magnetic powders coated with the organic binder; Granulation and pressing: the iron-based magnetic powder coated with the organic binder is placed in a vacuum drying oven to be dried into an iron-based composite powder, and then the iron-based composite powder is pressed into a magnetic ring blank; Magnetic ring curing: The magnetic ring blank is heated and kept warm in an inert atmosphere to complete the curing process, and then taken out after cooling to room temperature in the furnace to obtain an iron-based soft magnetic powder core with a multi-particle size distribution.

6. The method for preparing an iron-based soft magnetic powder core based on multiple particle size distribution according to claim 5, characterized in that: The preparation of the organic binder solution includes dissolving 2 wt.% of the total weight of the annealed pretreated iron-based magnetic powders of different particle sizes in an organic solvent, wherein the organic binder includes at least one of epoxy resin, silicone resin, polyimide resin, and phenolic resin, and the organic solvent includes acetone or anhydrous ethanol.

7. The method for preparing an iron-based soft magnetic powder core based on multiple particle size distribution according to claim 1 or 5, characterized in that: The particle size of the iron-based composite powder obtained by granulation is 10-300 μm.

8. The method for preparing an iron-based soft magnetic powder core based on multiple particle size distribution according to claim 1 or 5, characterized in that: The forming pressure of the press forming process is 600~1000 MPa, and the holding time is 60~180 s.

9. The method for preparing an iron-based soft magnetic powder core based on multiple particle size distribution according to claim 1 or 5, characterized in that: When the magnetic ring is cured, it is heated to 200 °C at a heating rate of 5-10 °C / min and kept at this temperature for 60-180 min.

10. An iron-based soft magnetic powder core based on multi-particle size distribution, characterized in that: The soft magnetic powder core is prepared by the method for preparing an iron-based soft magnetic powder core based on multiple particle size distributions as described in any one of claims 1 to 9.

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