Soft magnetic composite material, preparation method and application

Abstract

The invention discloses a soft magnetic composite material, a preparation method and application, the soft magnetic composite material comprises first powder, second powder, third powder and auxiliary materials, and the first powder comprises at least one of FeSiBNbCu, FeSiBMoCu and FeSiBVCu; the powder II and the powder III comprise at least one of alloy Fe-Si-Cr, Fe-Ni, Fe-Si, Fe-Si-Al, nanocrystalline powder or amorphous powder; the auxiliary material comprises at least one of a passivating agent, an insulating agent and a lubricating agent; the average particle size of the first powder is 20-30 microns, the average particle size of the second powder is smaller than 20 microns, and the average particle size of the third powder is smaller than or equal to 5 microns. According to the invention, through multi-particle-size compounding, a plurality of powder materials with different particle sizes and auxiliary materials are mixed according to a specific sequence, stirred and dried, so that the soft magnetic composite material with stable structure, high mechanical strength and high density can be obtained, and the saturation magnetization characteristic of a molded inductor product is improved.

Description

Technical Field

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

[0002] With the rapid development of mobile terminal devices and IoT technology, electronic devices are evolving towards miniaturization, higher frequency, and energy efficiency, leading to the widespread application of inductors. High-capacity, high-speed CPU power circuits in computers, automotive electronics, and distributed power systems demand stable operation of inductors under high-frequency and high-current conditions. Magnetic powder composite materials, as the core basic material for inductors, directly determine the high-frequency characteristics of the inductor. Specifically, these inductors require magnetic powder composite materials to possess high resistivity to ensure stable operation in MHz-level high-frequency environments, while also needing high permeability to meet the inductor's ability to sense external magnetic fields and achieve low losses.

[0003] The manufacturing process of the aforementioned inductors typically involves embedding a wound coil into magnetic powder, pressing it into shape using a press, and then heating and curing it to form the inductor device. However, when using soft magnetic materials as the magnetic powder, such inductors are generally only suitable for environments with frequencies below 1 MHz. At frequencies above 1 MHz, significant drops in inductance or surface overheating occur, leading to device failure. Therefore, improving the resistivity of the soft magnetic powder to maintain both high saturation magnetic flux density and high resistivity, thereby expanding the high-frequency application range of such inductors, has become a key research direction for those skilled in the art.

[0004] In the prior art, invention patent CN101694800A discloses a composite soft magnetic material and its preparation method suitable for high-frequency and high-power applications. This method prepares Fe / SiO2 core-shell composite soft magnetic powder with controllable coating thickness and complete insulation by uniformly coating an amorphous silicon dioxide shell onto the surface of particles with an average particle size of 30 μm < D < 150 μm. A molded inductor with high density, high resistivity, and high saturation magnetic induction is then prepared using a powder compaction molding process. Although this method effectively suppresses eddy current losses between particles by coating with a high-resistivity film, its effect on suppressing eddy current losses within the particles is limited.

[0005] Furthermore, invention patent CN104575913A discloses a method for preparing a low-loss amorphous magnetic powder core. This method, by adding high-temperature insulating materials and optimizing the insulation coating process, combined with pressing and high-temperature annealing processes, produces molded inductors with high permeability and good mechanical strength. However, although amorphous soft magnetic materials have high resistivity, the addition of a large number of amorphous forming elements in their formulation leads to a decrease in saturation magnetization. To improve the performance of amorphous soft magnetic powder cores and reduce high-frequency losses, a high-resistivity and well-adhesive insulating layer needs to be coated on the surface of the magnetic powder. Invention patent CN1224899A discloses a composite magnetic body, its manufacturing method, and Fe-Al-Si soft magnetic alloy powder used therein. It employs organic materials such as epoxy resin and phenolic resin as the insulating medium between magnetic powders. However, the organic insulating coating layer is prone to problems such as unevenness, agglomeration, and poor adhesion, and its poor heat resistance limits the heat treatment temperature of the magnetic powder core, resulting in poor performance. In contrast, using inorganic materials as the insulating coating layer can form a dense and uniform coating film. For example, nitric acid passivation can effectively suppress high-frequency eddy current losses and improve the quality factor of inductor devices, but because the reaction rate is difficult to control, the insulating layer is prone to expansion and cracking, ultimately leading to a decrease in insulation performance.

[0006] In summary, existing technologies that improve resistivity through a single coating layer cannot simultaneously address both eddy current losses and saturation magnetization within the particles. Summary of the Invention

[0007] To address existing problems, this invention provides a soft magnetic composite material, its preparation method, and its application. The soft magnetic powder prepared through multi-particle-size composite and stepwise coating processes has high resistivity and high saturation magnetization, which can significantly improve the operating frequency of molded inductors.

[0008] This invention provides a soft magnetic composite material, comprising powder one, powder two, powder three, and auxiliary materials. Powder one comprises at least one of FeSiBNbCu, FeSiBMoCu, and FeSiBVCu; powder two and powder three comprise at least one of alloys Fe-Si-Cr, Fe-Ni, Fe-Si, Fe-Si-Al, nanocrystalline or amorphous powder; and the auxiliary materials comprise at least one of passivating agent, insulating agent, and lubricant. The average particle size of powder one is 20-30 μm, the average particle size of powder two is less than 20 μm, and the average particle size of powder three is less than or equal to 5 μm. The auxiliary materials include at least one of passivating agent, insulating agent and lubricant.

[0009] This invention utilizes three different particle sizes of powder and auxiliary materials to obtain a soft magnetic composite material for molded inductors with smaller interparticle gaps and higher density. The larger particle size of the soft magnetic composite powder provides higher effective permeability, higher density, and higher mechanical strength; while the smaller particle size of the soft magnetic composite powder can suppress eddy current losses within the particles and strongly impede electron movement. In addition, the small particles fill the gaps between the large particles to form uniform micro-gaps, which both ensures density and suppresses eddy currents, reducing eddy current losses at high frequencies, improving the saturation magnetization characteristics of the molded inductor products, and increasing the operating current of the inductor products.

[0010] Preferably, the powder component 1 accounts for 50%-60% of the mass of the soft magnetic composite material.

[0011] Preferably, the second powder accounts for 10%-30% of the mass of the soft magnetic composite material.

[0012] Preferably, the mass percentage of the powder 3 in the soft magnetic composite material is 10%-30%.

[0013] Preferably, the auxiliary material accounts for 1%-10% of the mass of the soft magnetic composite material.

[0014] Preferably, the passivating agent is at least one of phosphoric acid, boric acid and sulfuric acid, and the passivating agent accounts for 0%-80% of the mass of the auxiliary material.

[0015] By selecting the aforementioned acid as a passivating agent, a chemical reaction occurs with the surface of the iron-based powder in the powder material, generating a strong, dense inorganic salt insulating film with strong adhesion to the matrix. This film can inhibit further oxidation of the powder and prevent excessive grain growth. At the same time, it has high thermal stability, enabling the soft magnetic composite material to withstand annealing processes and optimize magnetic properties.

[0016] Preferably, the insulating agent is at least one of epoxy resin, silicone resin and phenolic resin, and the mass percentage of the insulating agent in the auxiliary materials is 0%-80%.

[0017] In soft magnetic composite materials, organic resins such as epoxy resin, silicone resin, and phenolic resin are selected as insulating coating agents. The organic resin insulating agent forms a flexible, continuous, and dense organic polymer film on the surface of magnetic powder particles through physical coating, completely isolating each metal particle and blocking any conductive path, thereby greatly improving the overall resistivity of the material and reducing eddy current losses at high frequencies. In addition, it has excellent heat resistance during the pressing process, allowing it to be molded under higher pressure without cracking.

[0018] More preferably, the lubricant is at least one of zinc stearate, magnesium stearate, aluminum stearate, calcium stearate, and graphite powder, and the mass percentage of the lubricant in the auxiliary materials is 0%-80%.

[0019] In the preparation of soft magnetic composite materials, the above-mentioned lubricant can reduce the friction between powder particles and between the powder and the mold wall, so that the powder can flow and fill more evenly during pressing, thereby obtaining a compact with a more uniform density distribution and thus optimizing the magnetic properties.

[0020] On the other hand, the present invention also provides a method for preparing the aforementioned soft magnetic composite material, the method comprising the following steps: Step 1: Anneal the powder to obtain powder nanocrystal powder. Weigh the powder nanocrystal powder, powder two and powder three in proportion and mix them evenly to obtain composite magnetic powder. Step 2: Weigh the passivating agent according to the proportion and disperse it in the solvent to obtain a passivating agent solution. Mix the passivating agent solution with the composite magnetic powder to obtain passivated alloy powder. Step 3: Weigh the insulating agent according to the proportion and disperse it in the solvent to obtain an insulating agent solution. Mix the insulating agent solution with the passivation alloy powder and then process it to obtain a precursor. Weigh the lubricant according to the proportion and disperse it in the precursor and mix it evenly to obtain an insulating-coated magnetic powder composite material. After drying, a soft magnetic composite material is obtained.

[0021] The preparation method provided by the present invention involves mixing and stirring various powder materials and auxiliary materials of different particle sizes in a specific order, and then drying them to obtain a soft magnetic composite material with stable structure, high mechanical strength and density.

[0022] Preferably, in step 1, the annealing temperature is 530°C and the annealing time is 1 h.

[0023] Preferably, in step 2, the solvent is ethanol or acetone.

[0024] More preferably, in step 2, the mass ratio of the passivating agent to the solvent is 1:20-200.

[0025] Preferably, in step 2, the passivating agent solution is mixed with the composite magnetic powder to obtain passivating alloy powder, which includes: mixing the passivating agent solution with the composite magnetic powder, heating to 45°C and stirring for no more than 45 minutes, and then raising the temperature to 45°C-80°C to obtain passivating alloy powder.

[0026] By mixing and heating in stages as described above, the solvent in the passivating agent solution can be completely evaporated, resulting in dry passivated alloy powder.

[0027] Preferably, in step 3, the solvent is ethanol or acetone.

[0028] More preferably, in step 3, the mass ratio of the insulating agent to the solvent is 1:5-50.

[0029] Preferably, in step 3, the process of mixing the insulating agent solution with the passivation alloy powder to obtain the insulating alloy powder includes: mixing the insulating agent solution with the passivation alloy powder and stirring for a stirring time not exceeding 45 minutes.

[0030] Preferably, in step 3, when the lubricant is dispersed and mixed evenly in the precursor, the stirring time shall not exceed 45 min and the mixing temperature shall be 45℃-80℃.

[0031] Within the above-mentioned range of stirring time and mixing temperature, the solvent in the insulating solution can be completely evaporated, resulting in an insulating-coated magnetic powder composite material.

[0032] Preferably, in step 3, the drying temperature is 80°C and the drying time is 2 hours.

[0033] The present invention also provides a magnetic powder core prepared from the aforementioned soft magnetic composite material.

[0034] Preferably, the magnetic powder core has a permeability greater than 60 at 1 MHz and a magnetic loss less than 13000 mW / cm at 3 MHz and 50 mT. 3 .

[0035] The present invention also provides the application of the magnetic powder core in molded inductor products.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention utilizes multi-particle-size composite and step-by-step coating processes to regulate the air gap between particles in soft magnetic composite materials, forming uniform micro-air gaps to provide higher effective permeability. This ensures density while suppressing eddy currents, reducing eddy current losses at high frequencies, improving the saturation magnetization characteristics of molded inductor products, and increasing the operating current of inductor products.

[0037] The method for preparing soft magnetic composite materials provided by the present invention involves mixing and stirring various powder materials and auxiliary materials of different particle sizes in a specific order, and then drying them to obtain a soft magnetic composite material with stable structure, high mechanical strength and density. This results in the soft magnetic composite material having excellent properties of high resistivity, low loss and high permeability under high frequency conditions, which can significantly improve the operating frequency range of molded inductors. Attached Figure Description

[0038] Figure 1 This is a SEM image of the FeSiBNbCu powder provided in an embodiment of the present invention.

[0039] Figure 2This is a SEM image of the FePBC powder provided in an embodiment of the present invention.

[0040] Figure 3 This is a SEM image of the powdered 3FeNi provided in an embodiment of the present invention.

[0041] Figure 4 This is a SEM image of the soft magnetic composite material provided in an embodiment of the present invention. Detailed Implementation

[0042] The present invention will be further described in detail below with reference to embodiments and comparative examples.

[0043] Example 1 (1) Take FeSiBNbCu nanocrystalline precursor powder with a median particle size (D50) of 25 μm. Figure 1 ) and FePBC powder with a D50 of 15 μm ( Figure 2 FeNi powder with a D50 of 1 μm was taken ( Figure 3 ).

[0044] (2) Place the nanocrystalline precursor FeSiBNbCu powder in a tube furnace and anneal it at 5×10⁻⁶ ℃. -3 FeSiBNbCu nanocrystalline powder was obtained by annealing under vacuum at 530°C for 1 h.

[0045] (3) According to the ratio of 50 wt% FeSiBNbCu nanocrystalline powder, 20 wt% FePBC powder and 30 wt% FeNi powder, 100 parts of magnetic powder of different proportions were weighed to obtain composite magnetic powder. Phosphoric acid, a passivating agent, was weighed at a ratio of 0.2% of the total mass of the composite magnetic powder. The phosphoric acid was dissolved in a solvent to obtain a phosphoric acid solution. The solvent of the passivating agent solution was acetone. The passivating agent solution was mixed with the composite magnetic powder, heated to 60°C and maintained at 60°C, and then stirred for 45 min. Subsequently, the temperature was raised to 80°C to completely evaporate the solvent in the passivating agent solution to obtain dry passivated alloy powder.

[0046] (4) Weigh out the insulating epoxy resin at a ratio of 2% of the total mass of the composite magnetic powder, dissolve the epoxy resin in a solvent to obtain an insulating solution, wherein the solvent of the insulating solution is acetone, mix the insulating solution with the passivation alloy powder and stir for 45 min.

[0047] (5) Zinc stearate with a total mass fraction of 0.05 wt% composite magnetic powder is added to the solution in step (4) as a lubricant. The lubricant is mixed and stirred with the insulating alloy powder for 45 min. Then, it is heated to 80℃ to evaporate the solvent in the insulating solution to obtain the magnetic powder composite material after insulation coating.

[0048] (6) The magnetic powder composite material after insulation coating after step (5) is placed in an 80℃ forced-air drying oven and dried for 2 h to obtain a completely dried soft magnetic composite material. Figure 4 ).

[0049] (7) The soft magnetic composite material is poured into the hydraulic press mold and pressed into a ring magnetic powder core blank under the conditions of 1200 MPa pressure and 60 s holding pressure. The outer diameter, inner diameter and height are 20.3 mm, 12.7 mm and 2.5 mm, respectively.

[0050] (8) The annular magnetic powder core blank is placed in a vacuum furnace at 350℃ for stress relief heat treatment and held for 2 hours to obtain the magnetic powder core.

[0051] The magnetic powder core prepared in this embodiment was subjected to the following performance tests: loss test (the primary winding of the magnetic core has 20 turns of copper wire with a diameter of 0.5 mm, and the secondary winding has 5 turns with a diameter of 0.5 mm), inductance test, and DC bias test.

[0052] As shown in Table 1, the effective permeability of the magnetic powder core at 1 MHz is 61.2, and the magnetic loss at 3 MHz and 50 mT is 11570 mW / cm. 3 The DC bias under an applied DC field of 100 Oe is 65.4%.

[0053] Example 2 This embodiment is basically the same as Embodiment 1, except that, according to the ratio of 60 wt% FeSiBNbCu nanocrystalline powder, 10 wt% FePBC powder and 30 wt% FeNi powder, 100 parts of magnetic powder in different proportions were weighed to obtain composite magnetic powder.

[0054] The magnetic powder core prepared in this embodiment was subjected to the following performance tests: loss test (the primary winding of the magnetic core has 20 turns of copper wire with a diameter of 0.5 mm, and the secondary winding has 5 turns with a diameter of 0.5 mm), inductance test, and DC bias test.

[0055] As shown in Table 1, the effective permeability of the magnetic powder core at 1 MHz is 62.3, and the magnetic loss at 3 MHz and 50 mT is 12360 mW / cm. 3 The DC bias under an applied DC field of 100 Oe is 63.2%.

[0056] Example 3 This embodiment is basically the same as Embodiment 1, except that FeSiBNbCu nanocrystalline precursor powder with a median particle size (D50) of 20 μm and FePBC powder with a D50 of 10 μm are taken, and FeNi powder with a D50 of 5 μm are taken. According to the same ratio, 100 parts of magnetic powder of different proportions are weighed to obtain composite magnetic powder.

[0057] The magnetic powder core prepared in this embodiment was subjected to the following performance tests: loss test (the primary winding of the magnetic core has 20 turns of copper wire with a diameter of 0.5 mm, and the secondary winding has 5 turns with a diameter of 0.5 mm), inductance test, and DC bias test.

[0058] As shown in Table 1, the effective permeability of the magnetic powder core is 59.8 at 1 MHz, and the magnetic loss is 10458 mW / cm at 3 MHz and 50 mT. 3 The DC bias is 67.8% under an applied DC field of 100 Oe.

[0059] Example 4 This embodiment is basically the same as Embodiment 1, except that FeSiBNbCu nanocrystalline precursor powder with a median particle size (D50) of 30 μm and FePBC powder with a D50 of 10 μm are taken, and FeNi powder with a D50 of 2 μm is taken. According to the same ratio, 100 parts of magnetic powder of different proportions are weighed to obtain composite magnetic powder.

[0060] The magnetic powder core prepared in this embodiment was subjected to the following performance tests: loss test (the primary winding of the magnetic core has 20 turns of copper wire with a diameter of 0.5 mm, and the secondary winding has 5 turns with a diameter of 0.5 mm), inductance test, and DC bias test.

[0061] As shown in Table 1, the effective permeability of the magnetic powder core at 1 MHz is 62.9, and the magnetic loss at 3 MHz and 50 mT is 12850 mW / cm. 3 The DC bias under an applied DC field of 100 Oe is 62.8%.

[0062] Comparative Example 1 This comparative example is basically the same as Example 1, except that, according to the ratio of 20 wt% FeSiBNbCu nanocrystalline powder, 40 wt% FePBC powder and 40 wt% FeNi powder, 100 parts of magnetic powder in different proportions were weighed to obtain composite magnetic powder.

[0063] The magnetic powder core prepared in this comparative example was subjected to the following performance tests: loss test (the primary winding of the magnetic core has 20 turns of copper wire with a wire diameter of 0.5 mm, and the secondary winding has 5 turns with a wire diameter of 0.5 mm), inductance test, and DC bias test.

[0064] As shown in Table 1, the effective permeability of the magnetic powder core of the molded inductor using magnetic powder composite material is 57.9 at a frequency of 1 MHz, and the magnetic loss is 14485 mW / cm under the conditions of 3 MHz and 50 mT. 3 The DC bias is 65.8% under an applied DC field of 100 Oe.

[0065] Comparative Example 2 This comparative example is basically the same as Example 1, except that, according to the ratio of 10 wt% FeSiBNbCu nanocrystalline powder, 40 wt% FePBC powder and 50 wt% FeNi powder, 100 parts of magnetic powder in different proportions were weighed to obtain composite magnetic powder.

[0066] The magnetic powder core prepared in this comparative example was subjected to the following performance tests: loss test (the primary winding of the magnetic core has 20 turns of copper wire with a wire diameter of 0.5 mm, and the secondary winding has 5 turns with a wire diameter of 0.5 mm), inductance test, and DC bias test.

[0067] As shown in Table 1, the effective permeability of the magnetic powder core of the molded inductor magnetic powder composite material is 53.4 at a frequency of 1 MHz, and the magnetic loss is 16687 mW / cm under the conditions of 3 MHz and 50 mT. 3 The DC bias is 68.9% under an applied DC field of 100 Oe.

[0068] Comparative Example 3 This comparative example is basically the same as Example 1, except that, according to the ratio of 40 wt% FePBC powder and 60 wt% FeNi powder, 100 parts of different proportions of magnetic powder were weighed to obtain composite magnetic powder.

[0069] The magnetic powder core prepared in this comparative example was subjected to the following performance tests: loss test (the primary winding of the magnetic core has 20 turns of copper wire with a wire diameter of 0.5 mm, and the secondary winding has 5 turns with a wire diameter of 0.5 mm), inductance test, and DC bias test.

[0070] As shown in Table 1, the effective permeability of the magnetic powder core of the molded inductor using magnetic powder composite material is 51.8 at a frequency of 1 MHz, and the magnetic loss is 17378 mW / cm under the conditions of 3 MHz and 50 mT. 3 The DC bias is 70.5% under an applied DC field of 100 Oe.

[0071] Comparative Example 4 This comparative example is basically the same as Example 1, except that, according to the ratio of 30 wt% FeSiBNbCu nanocrystalline powder and 70 wt% FeNi powder, 100 parts of magnetic powder of different proportions were weighed to obtain composite magnetic powder.

[0072] The magnetic powder core prepared in this comparative example was subjected to the following performance tests: loss test (the primary winding of the magnetic core has 20 turns of copper wire with a wire diameter of 0.5 mm, and the secondary winding has 5 turns with a wire diameter of 0.5 mm), inductance test, and DC bias test.

[0073] As shown in Table 1, the effective permeability of the magnetic powder core of the molded inductor using magnetic powder composite material is 53.7 at a frequency of 1 MHz, and the magnetic loss is 15465 mW / cm under the conditions of 3 MHz and 50 mT. 3 The DC bias is 66.4% under an applied DC field of 100 Oe.

[0074] Table 1 Performance test results of the examples and comparative examples

[0075] As shown in Table 1, compared with the comparative example, the magnetic permeability and loss of the embodiment, which uses an appropriate ratio of large-particle-size nanocrystalline magnetic powder to small-particle-size amorphous powder FePBC and ultrafine FeNi, are better than those of the comparative example. The DC bias performance is inversely proportional to the magnetic permeability, and the results are consistent with the law. It can be seen that the optimal range is the ratio of 50-60 wt% FeSiBNbCu nanocrystalline powder, 10-30 wt% FePBC powder and 30 wt% FeNi powder.

Claims

1. A soft magnetic composite material, characterized by, The soft magnetic composite material comprises powder I, powder II, powder III and auxiliary materials, the powder I comprises at least one of FeSiBNbCu, FeSiBMoCu and FeSiBVCu; the powder II and the powder III comprise at least one of alloy Fe-Si-Cr, Fe-Ni, Fe-Si, Fe-Si-Al, nanocrystalline or amorphous powder; the auxiliary materials comprise at least one of passivator, insulating agent and lubricant. The average particle size of the powder I is 20-30 μm, the average particle size of the powder II is less than 20 μm, and the average particle size of the powder III is less than or equal to 5 μm.

2. The soft magnetic composite of claim 1, wherein, The mass ratio of the powder I in the soft magnetic composite material is 50%-60%; The mass ratio of the powder II in the soft magnetic composite material is 10%-30%; The mass ratio of the powder III in the soft magnetic composite material is 10%-30%; The mass ratio of the auxiliary materials in the soft magnetic composite material is 1%-10%.

3. The soft magnetic composite of claim 1, wherein, The passivator is at least one of phosphoric acid, boric acid and sulfuric acid; The insulating agent is at least one of epoxy resin, silicone resin and phenolic resin; The lubricant is at least one of zinc stearate, magnesium stearate, aluminum stearate, calcium stearate and graphite powder.

4. The soft magnetic composite of claim 1, wherein, The mass ratio of the passivator in the auxiliary materials is 0%-80%; The mass ratio of the insulating agent in the auxiliary materials is 0%-80%; The mass ratio of the lubricant in the auxiliary materials is 0%-80%.

5. A method of producing a soft magnetic composite material according to any one of claims 1 to 4, characterized in that, The preparation method comprises the following steps: Step 1: annealing treatment of the powder I to obtain nanocrystalline powder of the powder I, the nanocrystalline powder of the powder I, the powder II and the powder III are weighed according to the proportion and mixed uniformly to obtain composite magnetic powder; Step 2: the passivator is weighed according to the proportion and dispersed in a solvent to obtain a passivator solution, the passivator solution and the composite magnetic powder are mixed and treated to obtain passivated alloy powder; Step 3: the insulating agent is weighed according to the proportion and dispersed in a solvent to obtain an insulating agent solution, the insulating agent solution and the passivated alloy powder are mixed and treated to obtain a precursor, the lubricant is weighed according to the proportion and dispersed in the precursor to obtain an insulating coated magnetic powder composite material, and the soft magnetic composite material is obtained after drying.

6. The method of claim 5, wherein the soft magnetic composite material is prepared by a process comprising: In step 2, the mass ratio of the passivator to the solvent is 1:20-200; In step 3, the mass ratio of the insulating agent to the solvent is 1:5-50.

7. The method for preparing the soft magnetic composite material according to claim 5, characterized in that, In steps 2 and 3, the solvent is ethanol or acetone.

8. A magnetic powder core prepared from the soft magnetic composite material according to any one of claims 1-4.

9. The magnetic powder core according to claim 8, characterized by The magnetic powder core has a magnetic permeability of more than 60 at a frequency of 1 MHz and a magnetic loss of less than 13000 mW / cm at 3 MHz, 50 mT 3 .

10. Use of the magnetic powder core according to claim 8 or 9 in a molded inductor product.

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