A high-frequency high-performance iron-nickel alloy magnetic powder core, a preparation method and application thereof

Abstract

The present application relates to a kind of high-frequency high-performance iron-nickel alloy magnetic powder core and its preparation method and application, belong to metal magnetic powder core field, at least one problem in the prior art in the high-frequency application of metal magnetic powder core is solved, which is difficult to consider high permeability, high permeability stability, high quality factor, at least one of the problems in the low saturation magnetic induction intensity, preparation process is complicated.A kind of preparation method of high-frequency high-performance iron-nickel alloy magnetic powder core, comprising the following steps: S1, raw material preparation;S2, pretreatment;S3, after pretreatment, iron-nickel alloy powder and nano SiO2 Powder are blended, to obtain inorganic insulation coated powder;S4, inorganic insulation coated powder is added into first coating agent, to obtain inorganic+first organic insulation coated powder;S5, inorganic+first organic insulation coated powder is added into second coating agent, to obtain inorganic+double-layer organic insulation coated powder;S6, press forming.The present application improves the comprehensive magnetic property of iron-nickel magnetic powder core, and simplifies preparation process.

Description

Technical Field

[0001] This invention relates to the field of metal magnetic powder core materials technology, and in particular to a high-frequency, high-performance iron-nickel alloy magnetic powder core, its preparation method, and its application. Background Technology

[0002] With the development of high-precision electronic technology, inductor components are also moving towards miniaturization and high frequency. Developing novel magnetic powder core materials with high permeability and quality factor at high operating frequencies is key to developing new high-performance inductor components.

[0003] Traditional nickel-zinc ferrite powder cores have limited operating frequencies due to the Snoek's limit. Commercially available iron-silicon-aluminum, iron-silicon-molybdenum, and iron-nickel metal powder cores operate only up to a few hundred kilohertz, which is too low to meet the demands of high-frequency devices. Carbonyl ferrite powder cores have high Q values ​​and low-temperature permeability, but their permeability at high frequencies is low or their resistance to saturation is poor, hindering power density improvement and causing significant aging issues. Iron-nickel powder cores, also known as high-flux powder cores, can meet the miniaturization requirements of inductors. However, existing iron-nickel powder cores have low quality factors (Q) or low permeability at high frequencies, making them unsuitable for applications above 10MHz.

[0004] To meet the high power density and high frequency application requirements of inductors in the MHz band, it is urgent to develop a metal magnetic powder core with excellent comprehensive performance at high frequencies. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide a high-frequency high-performance iron-nickel alloy magnetic powder core and its preparation method and application, so as to solve at least one of the following problems existing in the prior art when metal magnetic powder cores are used in high-frequency applications: (1) it is difficult to achieve high permeability, high permeability stability and quality factor at the same time; (2) the saturation magnetic induction intensity is low; (3) the preparation process is complicated.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] This invention provides a method for preparing a high-frequency, high-performance iron-nickel alloy magnetic powder core, comprising the following steps:

[0008] S1. Raw material preparation:

[0009] The iron-nickel alloy powder obtained by physical vapor-phase condensation has an average particle size D < 2 μm and a [Fe] / [Ni] ratio of 0.8-1.2; where [Fe] and [Ni] represent the mass percentages of Fe and Ni in the chemical composition of the iron-nickel alloy powder.

[0010] S2, Pretreatment:

[0011] High-temperature pretreatment of iron-nickel alloy powder in an oxygen-free environment;

[0012] S3. The pretreated iron-nickel alloy powder and nano-SiO2 powder are blended by ball milling to obtain inorganic insulating coating powder.

[0013] S4. Mix the silicone resin, epoxy resin, coupling agent and diluent to obtain a mixed resin; the mass ratio of the silicone resin to the epoxy resin is (1-5):1, and the diluent is a volatile solvent.

[0014] A portion of the mixed resin is taken as the first resin, and rare earth-doped nano-ferrite powder is added to the first resin to obtain the first coating agent; the inorganic insulating coating powder obtained in S3 is added to the first coating agent, and the mixture is stirred until the diluent in the first coating agent is completely evaporated to obtain inorganic + first organic insulating coating powder.

[0015] S5. The remaining part of the mixed resin is used as the second resin. Nano Al2O3 powder is added to the second resin to obtain the second coating agent. The inorganic + first organic insulating coating powder obtained in S4 is added to the second coating agent. By stirring, the diluent in the second coating agent is completely evaporated to obtain inorganic + double-layer organic insulating coating powder.

[0016] S6. Pressing and molding: The inorganic + double-layer organic insulating coating powder obtained in S5 is pressed and molded to obtain an iron-nickel alloy magnetic powder core.

[0017] Furthermore, based on the mass of the iron-nickel alloy powder, in step S4, the total addition amount of silicone resin and epoxy resin is 1-8 wt%, and the addition amount of coupling agent is 0.5-3 wt%.

[0018] Further, in step S5, nano-Al2O3 powder and layered MoS2, or layered MoS2, are added to the second resin to obtain the second coating agent; the transverse size of the layered MoS2 sheets is 10-30 μm.

[0019] Furthermore, based on the mass of the iron-nickel alloy powder, in step S3, the amount of nano-SiO2 powder added is 2-6 wt%; and / or, in step S4, the amount of rare earth-doped nano-ferrite powder added is 0.5-2 wt%; and / or, in step S5, the amount of nano-Al2O3 powder added is 0.5-2 wt%.

[0020] Further, in step S4, the mass ratio of silicone resin to epoxy resin is (1.5-2.5):1; and / or,

[0021] In step S3, the particle size of the nano SiO2 powder is 20-70 nm; and / or, in step S4, the particle size of the rare earth-doped nano ferrite powder is 5-50 nm; and / or, in step S5, the particle size of the nano Al2O3 powder is 5-70 nm.

[0022] Furthermore, in step S1, the variation coefficient of the particle size distribution of the iron-nickel alloy powder, i.e., the CV value, is ≤25%; and / or,

[0023] The iron-nickel alloy powder is in the form of spherical particles, with each particle having a sphericity δ ≥ 99.6%; and / or,

[0024] The angle of repose of the iron-nickel alloy powder is <30°.

[0025] Furthermore, in step S4, the ferrite powder includes at least one of manganese-zinc ferrite powder, nickel-zinc ferrite powder, cobalt-zinc ferrite powder, nickel-copper-zinc ferrite powder, and manganese ferrite powder.

[0026] Furthermore, in step S6, the pressing pressure is 700-900 MPa.

[0027] The present invention also provides an iron-nickel alloy magnetic powder core prepared by the method described above.

[0028] The present invention also provides an application of the iron-nickel alloy magnetic powder core as described above in power electronic and magnetic components operating in the frequency range of 30MHz to 100MHz.

[0029] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0030] (1) This invention endows iron-nickel-based magnetic powder core materials with excellent comprehensive properties through multi-layer insulating coating, such as significantly improving permeability, permeability stability, and quality factor, especially in high-frequency applications. Specifically, this invention selects suitable iron-nickel alloy powder and nano-SiO2 powder, and uses a simple and easy-to-operate ball milling blending method to uniformly coat the surface of iron-nickel alloy powder particles with nano-SiO2 powder. This coating can effectively isolate the direct contact between metal particles, reduce eddy current losses, and thus help improve permeability, quality factor, and obtain a more stable rate of change of permeability. Compared to single-layer organic insulation coating, or the use of a single organic resin or a single organic resin for organic coating, this invention employs a double-layer organic insulation coating. Each layer of organic insulation coating includes two resins (silicone resin and epoxy resin) and an inorganic powder. By controlling the appropriate ratio of silicone resin and epoxy resin, the synergistic effect of the two is utilized to improve the permeability, permeability stability, and quality factor of the magnetic powder core, while also enhancing its mechanical strength and environmental adaptability. At the same time, the inorganic powders in the double coating, such as rare earth-doped nano-ferrite powder and Al2O3 powder, also contribute to improving the permeability, permeability stability, and quality factor of the magnetic powder core.

[0031] (2) Compared with simply using organic resin for organic insulation coating, the present invention adds rare earth-doped nano ferrite powder to the organic insulation coating layer, which can not only reduce magnetic loss to improve magnetic permeability and quality factor, but also improve saturation magnetic induction intensity, thereby improving the overall magnetic properties of the magnetic powder core.

[0032] (3) Compared with existing methods for achieving inorganic insulation coating (chemical reaction coating, sol-gel method, chemical vapor phase method, chemical coprecipitation method, etc.), this invention can achieve effective inorganic insulation coating by ball milling and blending suitable iron-nickel alloy powder and nano SiO2 powder. This not only simplifies the process and reduces costs, but also improves the performance of the magnetic powder core, which is conducive to large-scale application.

[0033] (4) In some preferred embodiments, by controlling the particle size and amount of SiO2 powder, controlling the particle size and amount of rare earth doped ferrite powder, controlling the particle size and amount of Al2O3 powder, and adding layered MoS2 in the second organic insulating coating, it is beneficial to further improve the comprehensive magnetic properties of the magnetic powder core. By controlling the amount of coating agent added and the ratio of organosilicon resin and epoxy resin, it is beneficial to ensure good mechanical properties and thermal stability while taking into account excellent magnetic properties, especially in the high frequency range.

[0034] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0035] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0036] Figure 1 SEM images of iron-nickel alloy powder selected for embodiments of the present invention; wherein, a is an SEM image of iron-nickel alloy powder with an average particle size of 0.8 μm, and b is an SEM image of iron-nickel alloy powder with an average particle size of 1.3 μm.

[0037] Figure 2 The following are particle size distribution diagrams of the iron-nickel alloy powder selected in the embodiments of the present invention, wherein (a) is a particle size distribution diagram with an average particle size of 0.8 μm, and (b) is a particle size distribution diagram with an average particle size of 1.3 μm;

[0038] Figure 3 SEM images of the iron-nickel alloy powder selected for Comparative Example 1.

[0039] Figure 4 The magnetic permeability of the magnetic powder cores prepared in Examples 1, 2, and Comparative Example 1 of this invention varies with frequency.

[0040] Figure 5 The curves showing the quality factor of the magnetic powder cores prepared in Examples 1, 2, and Comparative Example 1 of this invention as a function of frequency are shown.

[0041] Figure 6 The magnetic permeability of the magnetic powder cores prepared in Examples 1 and 7-10 of this invention varies with frequency.

[0042] Figure 7 The curves showing the quality factor of the magnetic powder cores prepared in Examples 1 and 7-10 of this invention as a function of frequency are shown. Detailed Implementation

[0043] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0044] Iron-nickel alloy powder is a key material for manufacturing high-performance magnetic powder cores. Its particle size and distribution, surface morphology, chemical composition, and powder form significantly influence the performance of the final magnetic powder core product. Existing methods for preparing iron-nickel alloy powder mainly include atomization, reduction-diffusion, and mechanical alloying. However, after detailed analysis, the inventors of this invention discovered that iron-nickel alloy powder prepared by physical vapor deposition (PVD) is more suitable for magnetic powder core preparation compared to these traditional methods. Nevertheless, most iron-nickel alloy powder raw materials currently used for magnetic powder core preparation on the market are still prepared using atomization, reduction-diffusion, and mechanical alloying methods, with very few involving PVD-prepared powders. Therefore, how to determine from the numerous types of PVD-prepared iron-nickel alloy powders suitable for solving the technical problem of unsatisfactory overall performance of the metal magnetic powder cores of this invention in high-frequency applications is currently a subject lacking in relevant technical reports.

[0045] Besides the selection of raw materials, the choice of coating agent and coating method used for insulating iron-nickel alloy powder also directly affects the performance of the final product. Currently, most coating processes for iron-nickel alloy powder are quite complex, especially inorganic coating processes. Moreover, the comprehensive performance of coated iron-nickel alloy powder at high frequencies, including permeability, quality factor, saturation magnetic induction, and magnetic loss, often has certain deficiencies, making it difficult to fully meet the application requirements under high-frequency and high-power conditions.

[0046] Based on this, in a first aspect, the present invention provides a method for preparing a high-frequency, high-performance iron-nickel alloy magnetic powder core, comprising the following steps:

[0047] S1. Raw material preparation:

[0048] The iron-nickel alloy powder obtained by physical vapor-phase condensation has an average particle size D < 2 μm and a [Fe] / [Ni] ratio of 0.8-1.2; where [Fe] and [Ni] represent the mass percentages of Fe and Ni in the chemical composition of the iron-nickel alloy powder.

[0049] S2, Pretreatment:

[0050] High-temperature pretreatment of iron-nickel alloy powder in an oxygen-free environment;

[0051] S3. The pretreated iron-nickel alloy powder and nano-SiO2 powder are blended by ball milling to obtain inorganic insulating coating powder.

[0052] S4. Mix the silicone resin, epoxy resin, coupling agent and diluent to obtain a mixed resin; the mass ratio of the silicone resin to the epoxy resin is (1-5):1, and the diluent is a volatile solvent.

[0053] A portion of the mixed resin is taken as the first resin, and rare earth-doped nano-ferrite powder is added to the first resin to obtain the first coating agent; the inorganic insulating coating powder obtained in S3 is added to the first coating agent, and the mixture is stirred until the diluent in the first coating agent is completely evaporated to obtain inorganic + first organic insulating coating powder.

[0054] S5. The remaining part of the mixed resin is used as the second resin. Nano Al2O3 powder is added to the second resin to obtain the second coating agent. The inorganic + first organic insulating coating powder obtained in S4 is added to the second coating agent. By stirring, the diluent in the second coating agent is completely evaporated to obtain inorganic + double-layer organic insulating coating powder.

[0055] S6. Pressing and molding: The inorganic + double-layer organic insulating coating powder obtained in S5 is pressed and molded to obtain an iron-nickel alloy magnetic powder core.

[0056] Compared with existing technologies, this invention endows iron-nickel-based magnetic powder core materials with superior comprehensive properties through multi-layer insulating coating. For example, it significantly improves permeability, permeability stability, and quality factor, especially in high-frequency applications. Specifically, this invention selects suitable iron-nickel alloy powder and nano-SiO2 powder, and uses a simple and easy-to-operate ball milling blending method to uniformly coat the surface of the iron-nickel alloy powder particles with nano-SiO2 powder. This coating can effectively isolate direct contact between metal particles, reduce eddy current losses, and thus help improve permeability, quality factor, and obtain a more stable rate of change of permeability. Compared to single-layer organic insulation coating, or the use of a single organic resin or a single organic resin for organic coating, this invention employs a double-layer organic insulation coating. Each layer of organic insulation coating includes two resins (silicone resin and epoxy resin) and an inorganic powder. By controlling the appropriate ratio of silicone resin and epoxy resin, the synergistic effect of the two is utilized to improve the permeability, permeability stability, and quality factor of the magnetic powder core, while also enhancing its mechanical strength and environmental adaptability. At the same time, the inorganic powders in the double coating, such as rare earth-doped nano-ferrite powder and Al2O3 powder, also contribute to improving the permeability, permeability stability, and quality factor of the magnetic powder core.

[0057] Compared to simply using organic resin for organic insulation coating, this invention adds rare earth-doped nano-ferrite powder to the organic insulation coating layer, which can not only reduce magnetic loss to improve magnetic permeability and quality factor, but also increase saturation magnetic induction intensity, thereby improving the overall magnetic properties of the magnetic powder core.

[0058] Compared with existing methods for achieving inorganic insulation coating (chemical reaction coating, sol-gel method, chemical vapor phase method, chemical coprecipitation method, etc.), this invention achieves effective inorganic insulation coating by ball milling and blending suitable iron-nickel alloy powder and nano-SiO2 powder. This not only simplifies the process and reduces costs, but also improves the performance of the magnetic powder core, which is conducive to large-scale application.

[0059] Therefore, it can be seen that the present invention effectively improves the overall magnetic properties of iron-nickel based magnetic powder cores and simplifies the preparation process by selecting materials and using multi-layer insulation coating.

[0060] For example, the diluent includes one or a mixture of several of acetone, ethanol, methanol, and toluene.

[0061] In some preferred embodiments, based on the mass of the iron-nickel alloy powder, in step S4, the total addition amount of the silicone resin and epoxy resin is 1-8 wt%, and the addition amount of the coupling agent is 0.5-3 wt%. By controlling the addition amount of resin and coupling agent within a suitable range, an optimized balance in terms of magnetic properties, mechanical strength, and thermal stability of the magnetic powder core can be ensured. If the addition amount of resin and / or coupling agent is too high, it will over-coat the iron-nickel alloy powder, affecting its magnetic properties, such as causing a decrease in magnetic permeability and saturation magnetic induction, and also reducing the mechanical strength, hardness, and thermal stability of the magnetic powder core, thereby affecting its durability in practical applications. If the addition amount of resin and / or coupling agent is too low, the expected modification effect cannot be achieved, such as being detrimental to improving mechanical properties and heat resistance, or failing to achieve the purpose of reducing magnetic loss, increasing magnetic permeability, and quality factor.

[0062] For example, the total amount of silicone resin and epoxy resin added is 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, and 7 wt%, and the amount of coupling agent added is 1.0 wt%, 1.5 wt%, 2.0 wt%, and 2.5 wt%.

[0063] In some preferred embodiments, in step S5, nano-Al2O3 powder and layered MoS2, or layered MoS2, are added to the second resin to obtain a second coating agent; the lateral dimensions of the layered MoS2 powder sheets are 10-30 μm. Preferably, based on the mass of the iron-nickel alloy powder, the total addition amount of the nano-Al2O3 powder and / or layered MoS2 is ≤3 wt%. The addition of layered MoS2 and the control of the total addition amount of inorganic matter in the second organic insulating coating within a suitable range are beneficial to further improve the permeability and quality factor of the magnetic powder core, especially at high frequencies.

[0064] In some preferred embodiments, in step S3, the amount of nano-SiO2 powder added is 2-6 wt%, based on the mass of the iron-nickel alloy powder. By controlling the amount of nano-SiO2 powder added within a suitable range, the quality factor and permeability at high frequencies can be better balanced. Excessive addition of nano-SiO2 powder is detrimental to improving permeability at high frequencies because too much SiO2 insulating material increases the content of non-magnetic substances in the magnetic powder core, thereby reducing the effective permeability. Conversely, insufficient addition of nano-SiO2 powder is detrimental to improving the quality factor at high frequencies because nano-SiO2 plays a crucial role in improving resistivity and reducing core losses; insufficient addition will prevent the full realization of its insulating and performance-improving effects.

[0065] For example, the amount of nano-SiO2 powder added is 2.5 wt%, 3.5 wt%, 4.5 wt%, and 5.5 wt%.

[0066] In some preferred embodiments, in step S4, based on the mass of the iron-nickel alloy powder, the amount of rare earth-doped nano-ferrite powder added is 0.5-2 wt%; and / or, in step S5, the amount of nano-Al2O3 powder added is 0.5-2 wt%; and / or, the amount of layered MoS2 powder added is 0.5-2 wt%. By reasonably controlling these proportions, the advantages of rare earth-doped nano-ferrite powder and nano-Al2O3 powder in improving the overall magnetic properties, enhancing mechanical strength, and improving thermal stability of the magnetic powder core can be fully utilized, achieving the optimal balance between performance and cost. Adding too much rare earth-doped nano-ferrite powder or Al2O3 powder will affect the magnetic coupling between magnetic powder particles, leading to increased magnetic loss and consequently decreased permeability; adding too little will not effectively utilize the performance-enhancing effects of rare earth-doped nano-ferrite powder or Al2O3 powder.

[0067] For example, the amount of rare earth-doped nano-ferrite powder, Al2O3 powder or layered MoS2 powder added is 0.8wt%, 1.0wt%, 1.2wt%, 1.5wt%, and 1.8wt%.

[0068] Preferably, in step S4, the mass ratio of the silicone resin to the epoxy resin is (1.5-2.5):1. Precisely controlling the ratio of the two resins is more conducive to achieving an optimized balance between excellent magnetic properties, mechanical properties, and thermal stability in the magnetic powder core. For example, the ratio of silicone resin to epoxy resin is 1.7:1, 2:1, or 2.2:1.

[0069] In some embodiments, in step S3, the particle size of the nano-SiO2 powder is 20-70 nm; and / or, in step S4, the particle size of the rare earth-doped nano-ferrite powder is 5-50 nm; and / or, in step S5, the particle size of the nano-Al2O3 powder is 5-70 nm. Exemplarily, the rare earth-doped nano-ferrite powder is spinel-type ferrite powder.

[0070] For example, the particle size of the nano-SiO2 is 30nm, 40nm, 50nm, or 60nm.

[0071] For example, the particle size of the rare earth-doped nano-ferrite powder is 10nm, 15nm, 20nm, 30nm, or 40nm. The particle size of the nano-Al2O3 powder is 10nm, 20nm, 30nm, 40nm, 50nm, or 60nm.

[0072] Preferably, the particle size of the nano-SiO2 powder is 20-40 nm.

[0073] Preferably, the particle size of the rare earth-doped nano-ferrite powder is 5-20 nm.

[0074] Preferably, the particle size of the nano-Al2O3 powder is 5-50 nm.

[0075] Optionally, the ferrite powder includes at least one of manganese-zinc ferrite powder, nickel-zinc ferrite powder, cobalt-zinc ferrite powder, nickel-copper-zinc ferrite powder, and manganese ferrite powder.

[0076] In some preferred embodiments, the molecular formula of the rare earth-doped ferrite powder is Ni. 0.5 Zn 0.5 RE x Fe 2- x O4, Mn 0.5 Zn 0.5 RE x Fe 2-x O4, Co 0.5 Zn 0.5 RE x Fe 2-x O4, wherein RE is a rare earth element, including but not limited to at least one of La, Ce, Tb, Nd, Eu, Sm, Gd, Sc, Dy, Yb, Ho, Er, Tm, Lu, and Y; x = 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, and 0.09.

[0077] In one embodiment, the Ni 0.5 Zn 0.5 RE x Fe2-x Methods for preparing O4 include: based on Ni 0.5 Zn 0.5 RE x Fe 2-x The chemical composition of O4 is determined by stoichiometrically measuring a salt solution of nickel chloride (X mol / L), zinc chloride (X mol / L), ferric chloride hexahydrate (X mol / L), and rare earth chloride (0.1 × X mol / L). This solution is diluted with 50-150 mL of deionized water and mixed. The homogeneous solution is placed in a constant-temperature water bath and heated to 75-85°C with stirring. NaOH is added dropwise to adjust the pH to 10-11, and stirring is continued for 2-4 hours to promote the reaction, resulting in a brownish-red precipitate. The precipitate is washed with deionized water until the pH drops to 7. The precipitate is separated using vacuum filtration, dried at 80-90°C for 16-32 hours, and then ground into powder to obtain rare earth-doped nickel-zinc ferrite powder. For example, X = 2-5 mol / L; for example, X = 3 mol / L or 4 mol / L.

[0078] For example, add 120 mL of deionized water, place the homogenized solution in a constant temperature water bath, heat to 82 °C and stir, add NaOH dropwise to adjust the pH to 10-11, and continue stirring for 3 hours; use vacuum filtration to separate the precipitate and dry it at 87 °C for 18 hours.

[0079] In some embodiments, the Mn 0.5 Zn 0.5 RE x Fe 2-x O4 or Co 0.5 Zn 0.5 RE x Fe 2-x O4 preparation method and Ni 0.5 Zn 0.5 RE x Fe 2-x Similar to O4, the difference is that nickel chloride is replaced with water and manganese chloride, or water and cobalt chloride, such as manganese chloride tetrahydrate or cobalt chloride hexahydrate.

[0080] In some embodiments, in step S1, the coefficient of variation (CV) of the particle size distribution of the iron-nickel alloy powder is ≤25%, more preferably 20% or less, and even more preferably 15% or less, which indicates that the particle size distribution of the iron-nickel alloy powder is narrow.

[0081] In some embodiments, in step S1, the particle size of the iron-nickel alloy powder also satisfies: D max -D min ≤2.4μm; more preferably D max -D min ≤1.8μm; Dmax For the maximum particle size, D min This is the minimum particle size.

[0082] In some embodiments, in step S1, the iron-nickel alloy powder is spherical particles, and the sphericity of each spherical particle is δ≥99.6%, which indicates that the iron-nickel alloy powder particles have high sphericity.

[0083] In some embodiments, in step S1, the angle of repose of the iron-nickel alloy powder is <30°, indicating that the iron-nickel alloy powder does not stick together and has good flowability. For example, the angle of repose is 25°.

[0084] In some embodiments, in step S1, the surface roughness Ra of the iron-nickel alloy powder is ≤100 nm. Preferably, Ra is ≤50 nm.

[0085] Preferred iron-nickel alloy powders are characterized by small particle size, narrow particle size distribution, non-adhesion, and good sphericity to further improve the magnetic properties of the magnetic powder core at high frequencies. Smaller and more uniform particle size of the iron-nickel alloy powder in the magnetic powder core results in lower eddy current losses, thereby improving the permeability and quality factor of the magnetic powder core. Non-adhesion between powder particles facilitates more uniform mixing of insulating materials, coupling agents, and organic resins, ensuring insulating material between particles, thus reducing losses and improving the permeability and quality factor of the magnetic powder core, making it more suitable for high-frequency operation. When the alloy powder has better sphericity and a smoother surface, the insulating material on the powder surface is less likely to break under high voltage, ensuring inter-particle insulation, thereby improving the permeability and quality factor of the magnetic powder core at high frequencies and achieving a more stable rate of change in permeability.

[0086] In some embodiments, the particle size distribution of the iron-nickel alloy powder includes:

[0087] Case (1): 85% or more of the Fe-Ni powder has a particle size of 0.3-1.2 μm; or

[0088] Case (2): 90% and above of the Fe-Ni powder has a particle size of 0.9-1.8 μm.

[0089] In some embodiments, in step S6, the pressure for pressing is 700-900 MPa.

[0090] For example, the compression molding pressure is 750 MPa, 800 MPa, or 850 MPa.

[0091] In some embodiments, in step S1, the chemical composition of the iron-nickel alloy powder, by mass percentage, includes: Fe: 49.5-50.4%, C≤0.05%, O≤0.35%, with the balance being Ni and unavoidable impurities.

[0092] In some preferred embodiments, in step S1, [Fe] / [Ni] is 0.95-1.05, and exemplarily, [Fe] / [Ni] = 1:1.

[0093] In some embodiments, during the pretreatment in step S2, the atmosphere of the oxygen-free environment includes one or more of hydrogen, argon, and nitrogen. The temperature of the high-temperature pretreatment is 400-650°C.

[0094] In some embodiments, in step S3, the parameters of the ball mill include: a ball-to-material mass ratio of 10:1 to 40:1; a rotation speed of 50 r / min to 500 r / min; and a time of 0.5 to 8 h.

[0095] In some embodiments, in steps S4 and S5, the stirring is mechanical stirring under ultrasonic oscillation conditions, and the mechanical stirring speed is 100-500 r / min.

[0096] Preferably, in step S4, the silicone resin includes at least one of methylphenyl silicone resin, bisphenol A type epoxy resin, polyimide modified silicone resin, and acrylate modified silicone resin.

[0097] Preferably, in step S4, the coupling agent includes at least one of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and titanium phosphate coupling agent.

[0098] In some embodiments, in step S1, the iron-nickel alloy powder is prepared by physical vapor-phase condensation, the main steps of which include:

[0099] (1) Add iron-nickel alloy raw materials with a purity of ≥99.9% into a high-temperature evaporator and evacuate to a vacuum degree of ≤10. -4 After Pa, nitrogen gas is introduced into the reaction system until the internal pressure is 100-200 kPa;

[0100] (2) Then turn on the plasma gun at the top of the high temperature evaporator to make its power reach 60-100kW to form iron-nickel alloy vapor, and let it be transported with the nitrogen gas flow at a velocity of 2-5m / s to the particle controller connected to the high temperature evaporator for collision and fusion.

[0101] (3) These collision and fusion particles are transported with nitrogen to the bottom of the collector hopper to obtain iron-nickel alloy powder with a purity of ≥99% and an average particle size of <2μm.

[0102] In some embodiments, the preparation method of the nano-SiO2 powder specifically includes the following steps:

[0103] (1) Mix anhydrous ethanol, water and ammonia in a ratio of (35-40):1:3, and sonicate for 10-30 minutes. This mixture is called solution A. The concentration of ammonia is 20%-30%. For example, the ratio of anhydrous ethanol, water and ammonia is 37.5:1:3, and the concentration of ammonia is 25%.

[0104] (2) Dissolve 3-9 ml of hexyl orthosilicate in 40-60 ml of anhydrous ethanol and sonicate for 20-40 min, and record it as solution B; for example, the volume of hexyl orthosilicate is 6 ml and the volume of anhydrous ethanol is 50 ml.

[0105] (3) After stirring solution A at a constant temperature of 30-70℃ for 5-20 minutes, slowly pour solution B into it in 1-3 portions. After reacting for a certain period of time until the solution becomes turbid, collect the solution. After filtration and washing, obtain the filter residue. Dry the filter residue under vacuum to obtain nano-SiO2 powder. For example, slowly pour solution B into it in 2 portions and dry it under vacuum at 100℃.

[0106] Secondly, the present invention also provides an iron-nickel alloy magnetic powder core obtained by the preparation method described in the first aspect.

[0107] In some embodiments, the iron-nickel alloy magnetic powder core has a permeability >22, a maximum quality factor >240, and a frequency corresponding to the maximum quality factor >32MHz at high frequencies of 30MHz to 100MHz. The quality factor at 100MHz is above 39.

[0108] In some embodiments, the working temperature range of the iron-nickel alloy magnetic powder core is -60℃ to 200℃, and the density after pressing is ≥6.8g / cm³. 3 The saturation magnetic induction intensity Bs ≥ 1.30T.

[0109] Thirdly, the present invention also provides an application of the iron-nickel alloy magnetic powder core as described in the second aspect in power electronic and magnetic components operating in the frequency range of 30MHz to 100MHz.

[0110] The power electronic and magnetic components include, but are not limited to: inductors, transformers, filters, and chokes.

[0111] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and comparative examples.

[0112] Example 1:

[0113] This embodiment provides a method for preparing a high-frequency, high-performance iron-nickel alloy magnetic powder core, including the following steps:

[0114] S1. Raw material preparation:

[0115] The iron-nickel alloy powder obtained by physical vapor condensation had an average particle size D = 1.3 μm. Its chemical composition is shown in Table 1, and SEM images are shown below. Figure 1 As shown in (b), the particle size distribution is shown in [the figure]. Figure 2 (b);

[0116] Table 1: Composition of Iron-Nickel Alloy (Average Particle Size D = 1.3 μm)

[0117] Element Fe Ni C O Content by mass (wt%) 50.08 margin 0.032 0.277

[0118] S2, Pretreatment:

[0119] The iron-nickel alloy powder was pretreated at 450°C for 1 hour in a H2 / Ar mixed gas environment with a volume ratio of 1:1.

[0120] S3. The high-temperature pretreated iron-nickel alloy powder and SiO2 powder are blended by ball milling to obtain an inorganic insulating coating powder; the average particle size of the SiO2 powder is 72nm and the addition amount is 1wt%.

[0121] S4, silicone resin Epoxy resin AFG-90H and coupling agent vinyltriethoxysilane are mixed in acetone to obtain a mixed resin. Based on the mass of iron-nickel alloy powder, the total amount of silicone resin and epoxy resin added is 8 wt%, wherein the mass ratio of silicone resin to epoxy resin is 1:1, and the amount of coupling agent added is 3 wt%.

[0122] Half of the mixed resin is taken as the first resin, and rare earth-doped ferrite powder is added to the first resin to obtain the first coating agent; wherein, the rare earth-doped ferrite powder is manganese-zinc ferrite powder doped with the rare earth element Sm, and its chemical formula is Mn 0.5 Zn 0.5 RE x Fe 2-x O4, RE is Sm, x = 0.02, its average particle size is 14.6 nm and the addition amount is 2.0 wt%; the inorganic insulating coating powder obtained by S3 is added to the first coating agent, and mechanically stirred at 300 r / min under ultrasonic oscillation conditions until acetone is completely evaporated to obtain inorganic + first organic insulating coating powder;

[0123] S5. The remaining 1 / 2 portion of the mixed resin is used as the second resin. Nano Al2O3 powder is added to the second resin to obtain the second coating agent. The average particle size of the Al2O3 powder is 64 nm and the addition amount is 2.0 wt%. The inorganic + first organic insulating coating powder obtained in S4 is added to the second coating agent. The mixture is mechanically stirred at 300 r / min under ultrasonic oscillation conditions until the acetone is completely evaporated to obtain the inorganic + double-layer organic insulating coating powder.

[0124] S6. Pressing and molding: The inorganic + double-layer organic insulating coating powder obtained in S5 is pressed and molded at 700 MPa to obtain an iron-nickel alloy magnetic powder core.

[0125] Example 2:

[0126] The difference between this embodiment and Embodiment 1 is that in step S1, the average particle size of the iron-nickel alloy powder is 0.8 μm, the chemical composition is shown in Table 2, and the SEM image is shown below. Figure 1 As shown in (a), the particle size distribution is shown in the figure. Figure 2 (a) In step S4, the total amount of silicone resin and epoxy resin added is 1 wt%, the mass ratio of silicone resin to epoxy resin is 5:1, the amount of coupling agent added is 0.5 wt%, the amount of rare earth doped manganese zinc ferrite powder added is 0.5 wt%, and in step S5, the amount of Al2O3 powder added is 0.5 wt%. The remaining steps and parameters are similar to those in Example 1.

[0127] Table 2: Composition of Iron-Nickel Alloy (Average Particle Size D = 0.8 μm)

[0128] Element Fe Ni C O Content by mass (wt%) 50.21 margin 0.033 0.327

[0129] Example 3:

[0130] The difference between this embodiment and Embodiment 2 is that: in step S4, the total amount of silicone resin and epoxy resin added is 3 wt%, the mass ratio of silicone resin to epoxy resin is 1.5:1, the amount of coupling agent added is 1.0 wt%, the amount of rare earth-doped manganese zinc ferrite powder added is 1.5 wt%, and in step S5, the amount of Al2O3 powder added is 1.5 wt%; the remaining steps and parameters are similar to those in Embodiment 2.

[0131] Example 4:

[0132] The difference between this embodiment and Embodiment 2 is that: in step S4, the total amount of silicone resin and epoxy resin added is 6 wt%, the mass ratio of silicone resin to epoxy resin is 2.5:1, the amount of coupling agent added is 1.5 wt%, the amount of rare earth-doped manganese zinc ferrite powder added is 1.25 wt%, and in step S5, the amount of Al2O3 powder added is 1.25 wt%; the remaining steps and parameters are similar to those in Embodiment 2.

[0133] Example 5:

[0134] The difference between this embodiment and embodiment 4 is that in step S4, the total amount of silicone resin and epoxy resin added is 5 wt%, the mass ratio of silicone resin to epoxy resin is 2:1, and the amount of coupling agent added is 2 wt%; the remaining steps and parameters are similar to those in embodiment 4.

[0135] Example 6:

[0136] The difference between this embodiment and embodiment 5 is that in step S3, the average particle size of the SiO2 powder is 30 nm; the remaining steps and parameters are similar to those in embodiment 5.

[0137] Example 7:

[0138] The difference between this embodiment and Embodiment 1 is that in step S3, the average particle size of the SiO2 powder is 30 nm and the addition amount is 2 wt%; the remaining steps and parameters are similar to those in Embodiment 1.

[0139] Example 8:

[0140] The difference between this embodiment and Embodiment 1 is that in step S3, the average particle size of the SiO2 powder is 30 nm and the addition amount is 4 wt%; the remaining steps and parameters are similar to those in Embodiment 1.

[0141] Example 9:

[0142] The difference between this embodiment and Embodiment 1 is that in step S3, the average particle size of the SiO2 powder is 30 nm and the addition amount is 6 wt%; the remaining steps and parameters are similar to those in Embodiment 1.

[0143] Example 10:

[0144] The difference between this embodiment and Embodiment 1 is that in step S3, the average particle size of the SiO2 powder is 30 nm and the addition amount is 8 wt%; the remaining steps and parameters are similar to those in Embodiment 1.

[0145] Example 11

[0146] The difference between this embodiment and Embodiment 6 is that: in step S3, the amount of SiO2 powder added is 6 wt%; in step S4, the rare earth-doped ferrite powder is rare earth element Dy-doped nickel-zinc ferrite powder, and its chemical formula is Ni 0.5 Zn 0.5 RE x Fe 2-x O4, RE is Dy, x = 0.05, average particle size is 12.4 nm and addition amount is 1.25 wt%; the remaining steps and parameters are similar to those in Example 6.

[0147] Example 12

[0148] The difference between this embodiment and Embodiment 11 is that in step S4, the rare earth-doped ferrite powder is a nickel-zinc ferrite powder doped with the rare earth element Yb, and its chemical formula is Ni. 0.5 Zn 0.5 RE x Fe 2-x O4, RE is Yb, x = 0.02, and the average particle size is 10.9 nm; the remaining steps and parameters are similar to those in Example 11.

[0149] Example 13

[0150] The difference between this embodiment and Embodiment 11 is that in step S4, the rare earth-doped ferrite powder is a cobalt-zinc ferrite powder doped with the rare earth element Yb, and its chemical formula is Co. 0.5 Zn 0.5 RE x Fe 2-x O4, RE is Yb, x = 0.09, and the average particle size is 8.1 nm; the remaining steps and parameters are similar to those in Example 11.

[0151] Example 14

[0152] The difference between this embodiment and embodiment 13 is that in step S5, the average particle size of the Al2O3 powder is 30 nm; the remaining steps and parameters are similar to those in embodiment 13.

[0153] Example 15

[0154] The difference between this embodiment and embodiment 13 is that: in step S5, layered MoS2 is added to the second resin to obtain the second coating agent; the average transverse size of the layered MoS2 sheets is 15 μm and the addition amount is 1.25 wt%; the remaining steps and parameters are similar to those in embodiment 13.

[0155] Comparative Example 1

[0156] The difference between this comparative example and Example 1 is that, in step S1, the average particle size D of the iron-nickel alloy powder is 3.2 μm, as shown in the SEM image. Figure 3 As shown; the remaining steps and parameters are similar to those in Example 1.

[0157] Comparative Example 2

[0158] The difference between this comparative example and Example 1 is that in step S4, the mass ratio of silicone resin to epoxy resin is 0.5:1; the remaining steps and parameters are similar to those in Example 1.

[0159] Comparative Example 3

[0160] The difference between this comparative example and Example 1 is that in step S4, the mass ratio of silicone resin to epoxy resin is 7:1; the remaining steps and parameters are similar to those in Example 1.

[0161] Comparative Example 4

[0162] The difference between this comparative example and Example 1 is that in step S4: 1 / 2 of the mixed resin is taken directly as the first coating agent (i.e., the first coating agent does not contain ferrite powder); the remaining steps and parameters are similar to those in Example 1.

[0163] Comparative Example 5

[0164] The difference between this comparative example and Example 1 is that in step S5, the remaining 1 / 2 portion of the mixed resin is directly used as the second coating agent (i.e., the second coating agent does not contain Al2O3 powder); the remaining steps and parameters are similar to those in Example 1.

[0165] Comparative Example 6

[0166] The difference between this comparative example and Example 1 is that step S3 is omitted; in step S4, the iron-nickel alloy powder after high-temperature pretreatment is directly added to the first coating agent (i.e., without SiO2 insulation coating); the remaining steps and parameters are similar to those in Example 1.

[0167] Comparative Example 7

[0168] The difference between this comparative example and Example 1 is that, in S4, the silicone resin... Epoxy resin AFG-90H and coupling agent vinyltriethoxysilane are mixed in acetone to obtain a mixed resin. Based on the mass of iron-nickel alloy powder, the total amount of silicone resin and epoxy resin added is 4 wt%, wherein the mass ratio of silicone resin to epoxy resin is 1:1, and the amount of coupling agent added is 1.5 wt%.

[0169] S5. Add nano-Al2O3 powder to the mixed resin to obtain a coating agent; wherein the average particle size of the Al2O3 powder is 64nm and the addition amount is 2.0wt%; add the inorganic insulating coating powder obtained in S3 to the coating agent, and mechanically stir at 300r / min under ultrasonic oscillation conditions until acetone is completely evaporated to obtain an inorganic + single-layer organic insulating coating powder; the remaining steps and parameters are similar to those in Example 1.

[0170] Comparative Example 8

[0171] The difference between this comparative example and Example 1 is that, in S4, the silicone resin... Epoxy resin AFG-90H and coupling agent vinyltriethoxysilane are mixed in acetone to obtain a mixed resin. Based on the mass of iron-nickel alloy powder, the total amount of silicone resin and epoxy resin added is 4 wt%, wherein the mass ratio of silicone resin to epoxy resin is 1:1, and the amount of coupling agent added is 1.5 wt%.

[0172] Manganese zinc ferrite powder is added to a mixed resin to obtain a coating agent; wherein the average particle size of the manganese zinc ferrite powder is 20 nm and the addition amount is 2.0 wt%; the inorganic insulating coating powder obtained in S3 is added to the coating agent, and mechanically stirred at 300 r / min under ultrasonic oscillation conditions until acetone is completely evaporated to obtain an inorganic + single-layer organic insulating coating powder, which is then pressed and molded; step S5 is omitted; the remaining steps and parameters are similar to those in Example 1.

[0173] The Al2O3 and MoS2 used in the embodiments and comparative examples of this invention can be obtained commercially.

[0174] Performance testing and results analysis:

[0175] A. Magnetic properties

[0176] (1) From Table 4 and Figure 5 It can be seen that the maximum quality factor Q in Comparative Example 1 is max Q max The corresponding frequencies and the quality factor at 100MHz are significantly lower than those in Examples 1 and 2 of this invention. This indicates that iron-nickel alloy powder with an average particle size >2μm is not conducive to improving the quality factor of magnetic powder cores, especially in the high-frequency range of 30MHz-100MHz.

[0177] (2) As can be seen from Table 4, the saturation magnetic induction intensity of Comparative Example 4 is significantly lower than that of the embodiment of the present invention. This indicates that introducing rare earth-doped ferrite powder into the insulation coating of the magnetic powder core is beneficial to improving the saturation magnetic induction intensity of the magnetic powder core while ensuring high permeability and quality factor Q in the test frequency band.

[0178] (3) As can be seen from Table 4, the permeability and quality factor of Comparative Examples 5 and 6 are significantly lower than those of the embodiments of the present invention. This indicates that the introduction of nano-SiO2 and Al2O3 powders into the insulating coating of the magnetic powder core is beneficial to improving the permeability and quality factor Q, especially in the high frequency range of 30MHz-100MHz, which is more conducive to the application of the magnetic powder core at high frequencies.

[0179] (4) Furthermore, compared with Comparative Examples 4 and 5, the magnetic properties of Comparative Examples 7 and 8 decreased slightly, which shows that the organic resin and rare earth doping in the double-layer insulation coating have a positive effect on improving the overall magnetic properties of the iron-nickel alloy magnetic powder core.

[0180] (5) From Table 4 and Figure 4-7 As can be seen, the embodiments of the present invention, through inorganic + double-layer organic insulation coating, can obtain excellent magnetic properties, especially in the high frequency range of 30MHz to 100MHz, exhibiting high permeability, quality factor, and high saturation magnetic induction intensity, as well as a more stable rate of change of permeability. For example, in the test frequency band, most of them can achieve: permeability > 22, maximum quality factor > 240, frequency corresponding to the maximum quality factor > 32MHz, and quality factor at 100MHz is above 39, even reaching above 90, and saturation magnetic induction intensity is basically above 1.30T.

[0181] (6) Further analysis shows that by controlling the particle size and amount of SiO2 powder (as in Examples 6-10), it is beneficial to further improve the magnetic properties, especially to better balance high permeability and quality factor at high frequencies; by controlling the particle size of Al2O3 powder (as in Example 14), it is beneficial to further improve the magnetic properties, especially the permeability and quality factor at high frequencies; by adding layered MoS2 to the second organic insulating coating (as in Example 15), it is beneficial to further improve the magnetic properties, especially the permeability and quality factor at high frequencies.

[0182] B. Other performance

[0183] The magnetic powder core obtained in this embodiment of the invention has excellent temperature resistance and can operate normally within the temperature range of -60℃ to 200℃. This wide temperature range makes the magnetic powder core obtained in this embodiment of the invention suitable for various environmental conditions, including applications with extreme low and high temperatures; after pressing and molding, the density is ≥6.8g / cm³. 3The higher density indicates that the magnetic powder core pressed blanks obtained in the embodiments of the present invention have higher mechanical properties, and can better maintain their structural integrity and performance stability in environments with greater vibration or impact. Furthermore, the mechanical properties and thermal stability of Example 5 are comparable to those of Examples 3 and 4, and the magnetic properties are slightly improved. This demonstrates that controlling the mass ratio of silicone resin to epoxy resin is beneficial to achieving an optimized balance between magnetic properties, mechanical properties, and thermal stability. Compared to Comparative Examples 4 and 5, the mechanical properties and thermal stability of Comparative Examples 7 and 8 are further slightly decreased, indicating that the organic resin in the double-layer insulation coating has a positive effect on improving the mechanical properties and thermal stability of the iron-nickel alloy magnetic powder core.

[0184] Table 3: Raw materials and their proportions for the examples and comparative examples

[0185]

[0186]

[0187]

[0188] Table 4: Performance test results of the examples and comparative examples

[0189]

[0190]

[0191] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a high-frequency, high-performance iron-nickel alloy magnetic powder core, characterized in that, Includes the following steps: S1. Raw material preparation: The iron-nickel alloy powder obtained by physical vapor-phase condensation has an average particle size D < 2 μm and a [Fe] / [Ni] ratio of 0.8-1.2; where [Fe] and [Ni] represent the mass percentages of Fe and Ni in the chemical composition of the iron-nickel alloy powder. S2, Pretreatment: High-temperature pretreatment of iron-nickel alloy powder in an oxygen-free environment; S3. The pretreated iron-nickel alloy powder and nano-SiO2 powder are blended by ball milling to obtain inorganic insulating coating powder. S4. Mix the silicone resin, epoxy resin, coupling agent and diluent to obtain a mixed resin; the mass ratio of the silicone resin to the epoxy resin is (1-5):1, and the diluent is a volatile solvent. A portion of the mixed resin is taken as the first resin, and rare earth-doped nano-ferrite powder is added to the first resin to obtain the first coating agent; the inorganic insulating coating powder obtained in S3 is added to the first coating agent, and the mixture is stirred until the diluent in the first coating agent is completely evaporated to obtain inorganic + first organic insulating coating powder. S5. The remaining part of the mixed resin is used as the second resin. Nano Al2O3 powder is added to the second resin to obtain the second coating agent. The inorganic + first organic insulating coating powder obtained in S4 is added to the second coating agent. By stirring, the diluent in the second coating agent is completely evaporated to obtain inorganic + double-layer organic insulating coating powder. S6. Pressing and molding: The inorganic + double-layer organic insulating coating powder obtained in S5 is pressed and molded to obtain an iron-nickel alloy magnetic powder core.

2. The preparation method according to claim 1, characterized in that, Based on the mass of the iron-nickel alloy powder, in step S4, the total amount of the silicone resin and epoxy resin added is 1-8 wt%, and the amount of the coupling agent added is 0.5-3 wt%.

3. The preparation method according to claim 1, characterized in that, In step S5, nano-Al2O3 powder and layered MoS2, or layered MoS2, are added to the second resin to obtain the second coating agent; the transverse size of the layered MoS2 sheets is 10-30 μm.

4. The preparation method according to claim 1, characterized in that, Based on the mass of the iron-nickel alloy powder, in step S3, the amount of nano-SiO2 powder added is 2-6 wt%; and / or, in step S4, the amount of rare earth-doped nano-ferrite powder added is 0.5-2 wt%; and / or, in step S5, the amount of nano-Al2O3 powder added is 0.5-2 wt%.

5. The preparation method according to claim 1, characterized in that, In step S4, the mass ratio of the silicone resin to the epoxy resin is (1.5-2.5):1; and / or, In step S3, the particle size of the nano SiO2 powder is 20-70 nm; and / or, in step S4, the particle size of the rare earth-doped nano ferrite powder is 5-50 nm; and / or, in step S5, the particle size of the nano Al2O3 powder is 5-70 nm.

6. The preparation method according to claim 1, characterized in that, In step S1, the variation coefficient of the particle size distribution of the iron-nickel alloy powder, i.e., the CV value, is ≤25%; and / or, The iron-nickel alloy powder is in the form of spherical particles, with each particle having a sphericity δ ≥ 99.6%; and / or, The angle of repose of the iron-nickel alloy powder is <30°.

7. The preparation method according to claim 1, characterized in that, In step S4, the ferrite powder includes at least one of manganese-zinc ferrite powder, nickel-zinc ferrite powder, cobalt-zinc ferrite powder, nickel-copper-zinc ferrite powder, and manganese ferrite powder.

8. The preparation method according to claim 1, characterized in that, In step S6, the pressure for pressing and molding is 700-900 MPa.

9. An iron-nickel alloy magnetic powder core obtained by the preparation method according to any one of claims 1-8.

10. The application of the iron-nickel alloy magnetic powder core as described in claim 9 in power electronic and magnetic components operating in the frequency range of 30MHz to 100MHz.

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