Iron-based nanocrystalline magnetic powder core with high magnetic induction and ultrahigh magnetic conductivity and preparation process of iron-based nanocrystalline magnetic powder core

Abstract

The invention provides an iron-based nanocrystalline magnetic powder core with high magnetic induction and ultrahigh magnetic conductivity and a preparation process thereof, an iron-based amorphous master alloy strip is prepared, and lamellar amorphous powder and fine spherical amorphous powder with different thicknesses are prepared based on the iron-based amorphous master alloy strip; lamellar amorphous powder and fine spherical amorphous powder with different thicknesses are selected in proportion and subjected to multi-time multi-level coating, amorphous powder with coating layers on the surfaces is obtained, and the coating layers comprise a phosphate coating, a silane coupling layer, a ferrite layer and an organic layer from inside to outside; mixing the amorphous powder with the coating layer on the surface, a binder and a release agent, and performing compression molding in a vacuum or inert gas protection atmosphere to obtain a nanocrystalline magnetic powder core matrix; and the nanocrystalline magnetic powder core base body is subjected to aging heat treatment in the protective gas atmosphere, and the high-magnetic-induction and ultrahigh-magnetic-conductivity iron-based nanocrystalline magnetic powder core is obtained.

Description

Technical Field

[0001] This invention relates to the field of nanocrystalline magnetic powder cores, specifically to a high magnetic induction and ultra-high magnetic permeability iron-based nanocrystalline magnetic powder core and its preparation process. Background Technology

[0002] Iron-based nanocrystalline soft magnetic alloys are a new generation of metallic soft magnetic materials following silicon steel. They possess advantages such as high saturation magnetic induction, high initial permeability, low coercivity, and low loss. Nanocrystalline soft magnetic tape, after rigorous winding, assembly, and annealing, forms nanocrystalline three-dimensional wound cores, which are widely used in high-frequency power electronic transformers, filter inductors, and new energy inverters, exhibiting good loss characteristics in the 10-20 kHz frequency range. However, with the rapid development of power electronics technology, the trend towards miniaturization, high frequency, and high efficiency in power electronic equipment is becoming increasingly significant. Iron-based nanocrystalline wound cores are struggling to meet the performance requirements of ultra-high frequency power electronic equipment above 20 kHz. Firstly, the severe eddy current and magnetostrictive losses of nanocrystalline soft magnetic tape at ultra-high frequencies lead to significant temperature rise and reduced efficiency in the nanocrystalline core. Secondly, the poor surface quality and structural uniformity of nanocrystalline soft magnetic tape, low lamination factor, and air gaps formed during the winding process further exacerbate the high-frequency losses of the nanocrystalline core.

[0003] Nanocrystalline magnetic powder cores are composite soft magnetic materials made by mixing and pressing iron-based nanocrystalline soft magnetic material powder with insulating additives. Due to the small size of the ferromagnetic particles and their separation by a non-magnetic insulating medium, nanocrystalline magnetic powder cores have a much higher resistivity than metals and their alloys, resulting in lower eddy current losses and suitability for higher frequencies. Furthermore, due to the small particle size, skin effect is virtually nonexistent, and the permeability exhibits good stability with frequency. Nanocrystalline magnetic powder cores possess characteristics such as low loss, high permeability, high saturation magnetic flux density, high resistivity, excellent magnetic and thermal isotropy, and a wide operating frequency range. They overcome the shortcomings of low saturation magnetic flux density in ferrites and high eddy current losses at high frequencies in traditional metal soft magnetic alloys, while maximizing the advantages of both. This allows them to be applied in fields where traditional soft magnetic materials are insufficient. Due to these excellent properties, nanocrystalline magnetic powder cores are widely used in telecommunications, radar, television, and power supply technologies as inductive filters, frequency modulation chokes, and main oscillator cores in switching power supplies. With the rapid development of modern communication technology and the computer industry, higher requirements have been placed on the performance of nanocrystalline magnetic powder cores, and their demand is constantly increasing.

[0004] The processing flow of nanocrystalline magnetic powder cores mainly includes powder preparation, insulation coating, pressing, and heat treatment. The quality of the insulation coating on the surface of the magnetic powder particles directly determines the loss of the nanocrystalline magnetic powder core. Therefore, the insulation coating process is considered the most important step in the production and preparation of nanocrystalline magnetic powder cores and has been a key research focus in recent years. However, current research on insulation coating processes mainly focuses on the study of insulation coating agents and coating methods. For example, Zhang Zongyang et al. studied the coating and pressing of amorphous powder ground from nanocrystalline alloys to form nanocrystalline magnetic powder cores. These nanocrystalline magnetic powder cores have high quality factors and permeability, but poor loss performance and are difficult to prepare. Patent application No. 201310280793.2 discloses a low-loss Fe-based nanocrystalline magnetic powder core and its preparation method. Using FeSiBCuMY powder prepared by strip crushing as raw material, the powder is insulated, pressed, and then chemically treated to prepare the corresponding nanocrystalline magnetic powder core. The nanocrystalline magnetic powder core exhibits good DC bias characteristics, but due to the angularity of the powder, its loss is relatively high, exceeding 400 mW / cm under 50 kHz, 0.1 T test conditions. 3 .

[0005] The nanocrystalline magnetic powder cores mentioned in the aforementioned articles and patent applications not only failed to resolve the contradictory relationship between the permeability and loss of the nanocrystalline magnetic powder cores, but also, because the powders prepared by mechanically crushing amorphous ribbons often have sharp edges, they are more likely to puncture the insulation layer during the pressing process, leading to insulation failure, increased eddy current loss, and deterioration of the performance of the nanocrystalline magnetic powder cores. Summary of the Invention

[0006] The purpose of this invention is to provide a high-magnetic-induction, ultra-high-permeability iron-based nanocrystalline magnetic powder core and its preparation process, thereby overcoming the problems existing in the prior art. This invention, by mixing sheet powders and fine spherical powders of different sizes and using various multilayer insulating coating processes, can prepare nanocrystalline magnetic powder cores with high saturation magnetic induction, ultra-high permeability, high packing density, and ultra-high insulation. These cores possess excellent properties such as uniform structure, high strength, and low high-frequency loss, and can be used as various inductive components for filtering, current stabilization, and energy storage in various switching power supply modules.

[0007] This invention is achieved through the following technical solution: A process for preparing a high-magnetic-induction, ultra-high-permeability iron-based nanocrystalline magnetic powder core includes the following steps: Iron-based amorphous master alloy strip is prepared, wherein the composition of the iron-based amorphous master alloy strip is: Fe a M b X c Y d Cu eWhere M is one or more of Co and Ni, X is one or more of B, Si, P, and C, and Y is one or more of Nb, Zr, Ga, Mn, and Mo. In terms of atomic percentage, 61.2%≤a≤84.7%, 0≤b≤9.7%, 3.7%≤c≤20.8%, 0≤d≤7.2%, 0.3%≤e≤2.1%, and a+b+c+d+e=100%; Based on the iron-based amorphous master alloy strip, lamellar amorphous powders and micro-spherical amorphous powders of different thicknesses were prepared. Different thicknesses of lamellar amorphous powder and micro-spherical amorphous powder are selected in proportion and coated multiple times in multiple levels to obtain amorphous powder with a coating layer on the surface. The coating layer includes a phosphating layer, a silane coupling layer, a ferrite layer and an organic layer from the inside out. Amorphous powder with a coating layer on the surface, binder and release agent are mixed and pressed into shape under vacuum or inert gas protective atmosphere to obtain nanocrystalline magnetic powder core matrix; The nanocrystalline magnetic powder core matrix is ​​subjected to aging heat treatment in a protective gas atmosphere to obtain a high magnetic induction and ultra-high magnetic permeability iron-based nanocrystalline magnetic powder core.

[0008] Furthermore, in the iron-based amorphous master alloy strip: 75.5%≤a≤84.5%; And / or, 0.1% ≤ b ≤ 6.4%; And / or, 8.7% ≤ c ≤ 14.5%; And / or, 0.1% ≤ d ≤ 4.5%; And / or, 0.5%≤e≤2.0%.

[0009] Furthermore, the preparation of the iron-based amorphous master alloy strip specifically involves: A master alloy ingot is melted by vacuum suspension melting to obtain a master alloy melt. Based on the master alloy melt, a first iron-based amorphous master alloy strip and a second iron-based amorphous master alloy strip are prepared by single-roll melt quenching process and double-roll thin strip casting and rolling process, respectively. In the single-roll melt quenching process, the roller speed is 20~40 m / s, and the resulting first iron-based amorphous master alloy strip has a casting strip width of 40~120 mm and a thickness of 20~30 μm; in the twin-roll thin strip casting and rolling process, the roller speed is 2~8 m / s, and the resulting second iron-based amorphous master alloy strip has a casting strip width of 30~80 mm and a thickness of 120~240 μm.

[0010] Furthermore, the preparation of lamellar amorphous powders and fine spherical amorphous powders of different thicknesses based on the iron-based amorphous master alloy strip specifically involves: The lamellar amorphous powder is obtained by ball milling using first iron-based amorphous master alloy strip and second iron-based amorphous master alloy strip as raw materials. Specifically, using the first iron-based amorphous master alloy strip as raw material, the ball milling process conditions are: ball-to-material ratio of 6:1, ball milling speed of 1800~2000 r / min, ball milling time of 2~5h, and the thickness of the obtained first near-circular lamellar amorphous powder is ≤22 μm and the diameter is ≤55 μm. Using the second iron-based amorphous master alloy strip as raw material, the ball milling process conditions are: ball-to-material ratio of 4:1, ball milling speed of 1300~1500 r / min, ball milling time of 1~4h, and the thickness of the obtained second near-circular lamellar amorphous powder is ≤130μm and the diameter is ≤75μm. The fine spherical amorphous powder is obtained by multi-stage pulverization and atomization using industrial-grade Fe, M, X, Y and Cu as raw materials. The multi-stage pulverization and atomization includes water atomization and high-speed rotating disc centrifugal atomization. Specifically, the water jet velocity during the water atomization process is 8~12 m / s, the rotation speed of the high-speed turntable during the high-speed turntable centrifugal atomization process is 13000~22000 r / min, and the average particle size range of the resulting fine spherical amorphous powder is 100~150 mesh.

[0011] Furthermore, lamellar amorphous powders and fine spherical amorphous powders of different thicknesses are selected in proportion and subjected to multiple multi-level coating processes, specifically: Select first near-circular lamellar amorphous powder, second near-circular lamellar amorphous powder, and micro-spherical amorphous powder in a mass ratio of 5:4:1, and coat them sequentially with a phosphating layer, a silane coupling layer, a ferrite layer, and an organic layer to obtain amorphous powder with a coating layer on the surface.

[0012] Furthermore, the coating process of the phosphating layer is as follows: A first near-circular lamellar amorphous powder is added to a first phosphate acetone solution, and stirred until the acetone completely evaporates, forming a phosphate layer on the surface of the first near-circular lamellar amorphous powder. A second near-circular lamellar amorphous powder is added to a second phosphate acetone solution, and stirred until the acetone completely evaporates, forming a phosphate layer on the surface of the second near-circular lamellar amorphous powder. A fine spherical amorphous powder is added to a phosphate acetone solution, and stirred until the acetone completely evaporates, forming a phosphate layer on the surface of the fine spherical amorphous powder, thus obtaining a phosphate-treated amorphous powder. The mass concentration of the first phosphate acetone solution is 4.5%, the mass concentration of the second phosphate acetone solution is 6%, and the mass ratio of the first phosphate acetone solution to the first near-circular lamellar amorphous powder and the mass ratio of the second phosphate acetone solution to the second near-circular lamellar amorphous powder is 1:(150~500); the mass concentration of the phosphate acetone solution is 3%, and the mass ratio of the phosphate acetone solution to the micro-fine spherical amorphous powder is 1:(200~1200). The coating process of the silane coupling layer is as follows: Add the coupling agent to an ethanol aqueous solution and stir until homogeneous. Adjust the pH and wait for the coupling agent to be fully hydrolyzed to obtain a coupling agent solution. Add the phosphating-treated amorphous powder to the coupling agent solution, stir thoroughly, pour off the solution, wash with ethanol solution, and dry to obtain the coupling-treated amorphous powder. The volume concentration of the ethanol aqueous solution is 95%; the mass ratio of the coupling agent to the ethanol aqueous solution is 1:(130~200); the pH adjustment specifically involves adjusting the pH to 8~11; and the mass ratio of the phosphating-treated amorphous powder to the coupling agent solution is 1:(1.2~2.4).

[0013] Furthermore, the coating process of the ferrite layer is as follows: Ferrite powder is dissolved in ethanol or acetone to obtain mixed solution A. Then, the coupled amorphous powder is stirred evenly with a mixture of epoxy resin and acetone to obtain mixed solution B. Mixed solution A and mixed solution B are mixed evenly and then dried at high temperature to obtain ferrite-coated amorphous powder. The ferrite powder is Mn-Zn ferrite, Ni-Zn ferrite, Co ferrite, or Ni ferrite; the concentration of the ferrite powder in the ethanol or acetone solution is 0.0001~0.01 g / mL; the mass ratio of the ferrite powder to the coupled amorphous powder is 1:(10~30); the amount of epoxy resin added in mixed solution B is 3%~7% of the mass of the amorphous powder, and the concentration of the amorphous powder in the acetone solution is 0.0001~0.01 g / mL; the volume ratio of solution A to solution B is 1:(0.8~1.2). The coating process of the organic layer is as follows: After mixing the ferrite-coated amorphous powder, add it to an acetone solution of epoxy resin, phenolic resin and silicone resin, so that the acetone solution of epoxy resin, phenolic resin and silicone resin completely covers the ferrite-coated amorphous powder. Stir until the acetone completely evaporates to obtain an amorphous powder with a coating layer on the surface. The mass ratio of epoxy resin, phenolic resin and silicone resin is (0.5~3.5):(1.5~5):(2.5~6.5), the mass ratio of organic resin to ferrite-coated amorphous powder is 1:(30~300), the concentration of ferrite-coated amorphous powder in acetone solution is 0.0001~0.01 g / mL, and the organic resin is epoxy resin, phenolic resin and silicone resin.

[0014] Furthermore, the amorphous powder with a surface coating, binder, and release agent are mixed and pressed into shape under a vacuum or inert gas protective atmosphere to obtain a nanocrystalline magnetic powder core matrix. The specific process is as follows: Amorphous powder with a surface coating, along with a binder and a release agent, is placed in a mold. First, the pressure is gradually increased to 200–400 MPa at room temperature, with a pressure loading rate of 10 MPa / min, and held for 10–30 min. After holding, the pressure is further increased to 800–1200 MPa at a pressure loading rate of 10 MPa / min, and held for 30–60 min at a holding temperature of 270–320℃. After holding, the pressure is gradually decreased to 50–100 MPa at a pressure unloading rate of 50 MPa / s, and held for 10–20 min at a holding temperature of 520–570℃. After holding, the pressure is increased again to 400–600 MPa at a pressure loading rate of 20 MPa / min, and held for 5–20 min, with the temperature gradually decreasing to room temperature during the pressure loading process, thus obtaining a nanocrystalline magnetic powder core matrix.

[0015] Furthermore, the aging heat treatment temperature is 100~300℃, and the holding time is 30~240 min.

[0016] A high-magnetic-induction and ultra-high-permeability iron-based nanocrystalline magnetic powder core is prepared using the above-mentioned process.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: Compared to existing iron-based nanocrystalline magnetic powder cores, the method of this invention uses a mixture of two sizes of broken lamellar amorphous powder from iron-based amorphous master alloy strips and one size of micro-spherical amorphous powder. By adjusting the ratio of the three types of amorphous powders, an extremely high lamellar amorphous powder packing density is obtained. The packing density is further increased by filling with micro-spherical amorphous powder, thereby improving the permeability of the iron-based nanocrystalline magnetic powder core. In the multi-level coating process, phosphating and silane coupling treatments greatly improve the stability of the coating layer (insulating coating layer). The ferrite layer forms good insulation on the surface of the amorphous powder while helping to improve the saturation magnetic induction intensity of the iron-based nanocrystalline magnetic powder core. The organic layer has extremely strong insulation and high-temperature resistance properties, which can reduce the coating layer thickness, increase the mass percentage of amorphous powder, and obtain excellent high-temperature resistance. This creates favorable conditions for the subsequent high-temperature heat treatment of the iron-based nanocrystalline magnetic powder core, thus obtaining an iron-based nanocrystalline magnetic powder core with both high saturation magnetic induction intensity and ultra-high permeability.

[0018] When the Fe content is 61.2%≤a≤84.7%, the amorphous forming ability and magnetic properties of the amorphous master alloy are guaranteed at the same time. When the content of M (Co, Ni) elements is 0≤b≤7.7%, the strong interactive coupling between Co, Ni and Fe elements can improve the saturation magnetic induction intensity of the amorphous master alloy. When the content of X (B, Si, P, C) elements is 3.7%≤c≤18.5%, the large atomic size difference between X elements and other elements can effectively improve the saturation magnetic induction intensity of the amorphous master alloy. When the content of Y (Nb, Zr, Ga, Mn, Mo) element is 0≤d≤5.2%, the large atomic radius of Y element can improve the thermal stability of amorphous master alloy and inhibit the rapid growth of nanocrystalline α-Fe(Si) grains in nanocrystalline magnetic powder core; When the Cu content is 0.3%≤e≤2.1%, Cu provides a large number of nucleation sites for the formation of nanoscale α-Fe(Si) grains, which increases the number density of nanocrystals and thus refines the grain size. Attached Figure Description

[0019] Figure 1 Diagrams showing the saturation magnetic induction intensity of nanocrystalline magnetic powder cores under different processing conditions; Figure 2 The permeability diagram of nanocrystalline magnetic powder cores under different process conditions. Detailed Implementation

[0020] The present invention will now be described in detail: This invention primarily addresses the difficulty in fabricating iron-based nanocrystalline magnetic powder cores that possess both high saturation magnetic induction and high permeability. Existing research has demonstrated that a uniform and well-designed insulating coating is crucial for achieving high-frequency, low-loss iron-based nanocrystalline magnetic powder cores. While high-frequency losses gradually decrease with increasing insulating coating thickness, their permeability and saturation magnetic induction also decline. To improve the permeability and saturation magnetic induction of iron-based nanocrystalline magnetic powder cores, this invention adjusts the powder packing structure and insulating coating process to simultaneously achieve a dense powder density and a thin, uniform insulating coating. This approach ensures low high-frequency losses while simultaneously enhancing the saturation magnetic induction and permeability of the iron-based nanocrystalline magnetic powder core.

[0021] Specifically, the present invention provides a process for preparing a high-magnetic-induction, ultra-high-permeability iron-based nanocrystalline magnetic powder core, comprising the following steps: (1) Preparation of iron-based amorphous master alloy strip: The master alloy ingot is melted by vacuum suspension melting to obtain master alloy melt. Based on the master alloy melt, the first iron-based amorphous master alloy strip and the second iron-based amorphous master alloy strip are prepared by single-roll melt quenching process and double-roll thin strip casting and rolling process, respectively. (2) Preparation of amorphous powder: Using the first iron-based amorphous master alloy strip and the second iron-based amorphous master alloy strip as raw materials, the first near-circular lamellar amorphous powder and the second near-circular lamellar amorphous powder were prepared by planetary ball mill. Fine spherical amorphous powders are prepared from industrial-grade Fe, M (Co, Ni), X (B, Si, P, C), Y (Nb, Zr, Ga, Mn, Mo), and Cu raw materials through multi-stage pulverization and atomization (using multi-stage pulverization and atomization equipment). (3) Insulation coating treatment: Select the first near-circular lamellar amorphous powder, the second near-circular lamellar amorphous powder and the micro-spherical amorphous powder in proportion, and perform multiple multi-level coating to obtain amorphous powder with a coating layer on the surface. The coating layer includes a phosphating layer, a silane coupling layer, a ferrite layer and an organic coating layer from the inside out. (4) Hot pressing-crystallization integrated molding: Amorphous powder with a coating layer on the surface, binder and release agent are placed into a pressing mold and pressed under vacuum or inert gas protection atmosphere to obtain nanocrystalline magnetic powder core matrix; (5) Aging heat treatment: The pressed nanocrystalline magnetic powder core matrix is ​​subjected to aging heat treatment in a protective gas atmosphere to obtain a high magnetic induction and ultra-high magnetic permeability iron-based nanocrystalline magnetic powder core.

[0022] The composition of the iron-based amorphous master alloy strip in step (1) is: Fe a M b X c Y d Cu eWhere M is one or more of Co and Ni, X is one or more of B, Si, P, and C, and Y is one or more of Nb, Zr, Ga, Mn, and Mo. In terms of atomic percentage, 61.2%≤a≤84.7%, 0≤b≤9.7%, 3.7%≤c≤20.8%, 0≤d≤7.2%, 0.3%≤e≤2.1%, and a+b+c+d+e=100%; Preferably, the Fe element content in the iron-based amorphous master alloy strip of the present invention is 75.5%~84.5%; Preferably, the content of M element in the iron-based amorphous master alloy strip of the present invention is 0.1%~6.4%; Preferably, the content of element X in the iron-based amorphous master alloy strip of the present invention is 8.7%~14.5%; Preferably, the Y element content in the iron-based amorphous master alloy strip of the present invention is 0.1%~4.5%; Preferably, the Cu content in the iron-based amorphous master alloy strip of the present invention is 0.5% to 2.0%.

[0023] In step (1), the roller speed in the twin-roll thin strip casting process is 2~8 m / s, and the width of the second iron-based amorphous master alloy strip is 30~80 mm and the thickness is 120~240 μm; in the single-roll melt spin quenching process, the roller speed is 20~40 m / s, and the width of the first iron-based amorphous master alloy strip is 40~120 mm and the thickness is 20~30 μm. In step (2), the amorphous powder has two specifications: near-circular lamellar and micro-spherical. The near-circular lamellar amorphous powder is made by grinding the first iron-based amorphous master alloy strip and the second iron-based amorphous master alloy strip using a planetary ball mill, respectively obtaining the first near-circular lamellar amorphous powder and the second near-circular lamellar amorphous powder. The micro-spherical amorphous powder is prepared by multi-stage pulverization and atomization, which includes two steps: water atomization and high-speed rotating disc centrifugal atomization. Preferably, the first iron-based amorphous master alloy strip is used as raw material, and the ball milling process conditions are: ball-to-material ratio of 6:1, ball milling speed of 1800~2000 r / min, and ball milling time of 2~5h. Preferably, the second iron-based amorphous master alloy strip is used as raw material, and the ball milling process conditions are: ball-to-material ratio of 4:1, ball milling speed of 1300~1500 r / min, and ball milling time of 1~4h. Preferably, in the multi-stage pulverization and atomization, the water jet velocity during water atomization is 8~12 m / s, and the rotation speed of the high-speed turntable during high-speed centrifugal atomization is 13000~22000 r / min; Preferably, the thickness of the first near-circular lamellar amorphous powder is ≤22 μm and the diameter is ≤55 μm; the thickness of the second near-circular lamellar amorphous powder is ≤130 μm and the diameter is ≤75 μm; and the average particle size of the fine spherical amorphous powder is in the range of 100~150 mesh.

[0024] In step (3), the first near-circular lamellar amorphous powder, the second near-circular lamellar amorphous powder, and the fine spherical amorphous powder are selected according to a mass ratio of 5:4:1, and are coated with a phosphating layer, a silane coupling layer, a ferrite layer, and an organic layer in sequence to obtain amorphous powder with a coating layer on the surface; the organic layer is a mixed coating layer of epoxy resin-phenolic resin-organic silicone resin. The specific process of phosphating coating in step (3) is as follows: First near-circular lamellar amorphous powder is added to first phosphate acetone solution, stirred until acetone is completely evaporated, and a phosphating layer is formed on the surface of the first near-circular lamellar amorphous powder; Second near-circular lamellar amorphous powder is added to second phosphate acetone solution, stirred until acetone is completely evaporated, and a phosphating layer is formed on the surface of the second near-circular lamellar amorphous powder; Micro-spherical amorphous powder is added to phosphate acetone solution, stirred until acetone is completely evaporated, and a phosphating layer is formed on the surface of the micro-spherical amorphous powder; The amorphous powder obtained in the three steps is collectively referred to as phosphated amorphous powder; Preferably, the mass concentration of the first phosphate acetone solution is 4.5%, the mass concentration of the second phosphate acetone solution is 6%, and the mass ratio of the first phosphate acetone solution to the first near-circular lamellar amorphous powder and the mass ratio of the second phosphate acetone solution to the second near-circular lamellar amorphous powder is 1:(150~500). Preferably, the mass concentration of the acetone phosphate solution used for phosphating the fine spherical amorphous powder is 3%, and the mass ratio of the acetone phosphate solution to the fine spherical amorphous powder is 1:(200~1200). The specific process of coating the silane coupling layer in step (3) is as follows: KH550 coupling agent is used. The coupling agent is added to an ethanol aqueous solution with a volume concentration of 95% and stirred evenly. The acidity and alkalinity of the solution are controlled by acetic acid or sodium hydroxide, which are acidic, neutral and alkaline respectively. After the coupling agent is fully hydrolyzed, a coupling agent solution is obtained. Phosphate-treated amorphous powder is added to the coupling agent solution. After stirring thoroughly, the solution is poured off. The remaining amorphous powder is washed with ethanol solution and dried to obtain coupling-treated amorphous powder. Preferably, the mass ratio between the coupling agent and the aqueous ethanol solution is 1:(130~200). Preferably, the pH is adjusted to be alkaline, with a pH of 6 to 9. Preferably, the mass ratio of the phosphated amorphous powder to the coupling agent solution is 1:(1.2~2.4).

[0025] The specific process of ferrite layer coating in step (3) is as follows: ferrite powder (Mn-Zn ferrite, Ni-Zn ferrite, Co ferrite, Ni ferrite, etc.) is dissolved in ethanol solution or acetone solution to obtain mixed solution A. Then, the amorphous powder that has been coupled is stirred evenly with the mixed solvent of epoxy resin and acetone solution to obtain mixed solution B. Mixed solution A and mixed solution B are mixed evenly and dried at high temperature to obtain ferrite-coated amorphous powder. Preferably, the ferrite powder is Mn-Zn ferrite, and the concentration of the ferrite powder in the ethanol solution or acetone solution is 0.0001~0.01 g / mL; Preferably, the mass ratio of the ferrite powder to the coupled amorphous powder is 1:(10~30). Preferably, the amount of epoxy resin added in mixed solution B is 3% to 7% of the mass of amorphous powder (first near-circular lamellar amorphous powder, second near-circular lamellar amorphous powder, and micro-fine spherical amorphous powder), and the concentration of amorphous powder in acetone solution is 0.0001 to 0.01 g / mL; the volume ratio of solution A to solution B is 1:(0.8 to 1.2). In step (3), the mass ratio of epoxy resin, phenolic resin, and silicone resin in the epoxy resin-phenolic resin-silicone resin mixed coating layer is (0.5~3.5):(1.5~5):(2.5~6.5). Preferably, the mass ratio of organic resin to ferrite-coated amorphous powder is 1:(30~300), the concentration of ferrite-coated amorphous powder in acetone solution is 0.0001~0.01g / mL, and the organic resin is epoxy resin, phenolic resin, or silicone resin.

[0026] The hot-pressing-crystallization integrated molding process described in step (4) is a step-by-step cold-pressing-hot-pressing hybrid pressing process. First, the amorphous powder with a coating layer on the surface, along with the binder and release agent, are placed into the mold. At room temperature, the pressure is gradually increased to 200~400 MPa at a pressure loading rate of 10 MPa / min and held for 10~30 min (referred to as the first stage). After holding the pressure, the pressure is further increased to 800~1200 MPa at a pressure loading rate of 10 MPa / min and held for 30~60 min at a holding temperature of 270~320℃ (referred to as the second stage). After holding the pressure, the pressure is gradually reduced to 50~100 MPa at a pressure unloading rate of 50 MPa / s and held for 10~20 min at a holding temperature of 520~570℃ (referred to as the third stage). After holding the pressure, the pressure is increased again to 400~600 MPa at a pressure loading rate of 20 MPa / min and held for 5~20 min. During the pressurization process, the temperature is gradually reduced to room temperature (referred to as the four stages) to obtain the nanocrystalline magnetic powder core matrix.

[0027] Preferably, the adhesive and the release agent are sodium silicate and barium stearate, respectively; Preferably, the first-stage pressure holding pressure is 280 MPa, and the pressure holding time is 15 min; Preferably, the second-stage holding pressure is 900 MPa, the holding time is 40 min, and the holding temperature is 310℃. Preferably, the three-stage pressure holding pressure is 50 MPa, the pressure holding time is 10 min, and the pressure holding temperature is 520℃. Preferably, the pressure holding time for the four stages is 500 MPa and the holding time is 10 min.

[0028] Preferably, in the hot pressing-crystallization integrated molding process, the inert gas protective atmosphere is high-purity hydrogen, helium, argon, nitrogen, neon, krypton, xenon, and carbon dioxide, etc.

[0029] The temperature required for the aging heat treatment in step (5) is 100~300℃, and the holding time required for the aging heat treatment is 30~240 min; Preferably, the holding temperature for the aging heat treatment is 180 °C; Preferably, the holding time for the aging heat treatment is 210 min.

[0030] The embodiments of the present invention will be described in detail below with reference to the examples. These embodiments represent preferred solutions of the present invention and should not be construed as limiting the scope of the invention. Unless otherwise specified, the methods and experimental equipment used in the following embodiments are conventional methods and instruments.

[0031] Example 1 A process for preparing a high-magnetic-induction, ultra-high-permeability iron-based nanocrystalline magnetic powder core includes the following steps: Step 1: Preparation of iron-based amorphous master alloy strip: The master alloy ingot is melted using a vacuum suspension melting method to obtain a master alloy melt. Based on the master alloy melt, a first iron-based amorphous master alloy strip and a second iron-based amorphous master alloy strip are prepared by a single-roll melt quenching process and a double-roll thin strip casting and rolling process, respectively. The composition of the iron-based amorphous master alloy strip is Fe. 0.755 Co 0.001 Ni 0.064 B 0.087 Si 0.056 P 0.031 Ga 0.001 Cu 0.005In the twin-roll thin strip casting and rolling process, the roller speed is 2 m / s, and the resulting second iron-based amorphous master alloy strip has a casting strip width of 30 mm and a thickness of 240 μm; in the single-roll melt spin quenching process, the roller speed is 20 m / s, and the resulting first iron-based amorphous master alloy strip has a casting strip width of 40 mm and a thickness of 30 μm. Step 2: Amorphous Powder Preparation: The first and second iron-based amorphous master alloy strips were crushed and ground into first and second near-circular lamellar amorphous powders respectively using a planetary ball mill. Using the first iron-based amorphous master alloy strip as raw material, the ball milling process conditions were: ball-to-material ratio of 6:1, ball mill speed of 1800 r / min, and ball milling time of 5 hours. The resulting first near-circular lamellar amorphous powder had a thickness of 20 μm and a diameter of 50 μm. Using the second iron-based amorphous master alloy strip as raw material, the ball milling process conditions were: ball-to-material ratio of 4:1, ball mill speed of 1300 r / min, and ball milling time of 4 hours. The resulting second near-circular lamellar amorphous powder had a thickness of 130 μm and a diameter of 70 μm. Micro-fine spherical amorphous powders were prepared using multi-stage pulverization and atomization. In the multi-stage pulverization and atomization process (including water atomization and high-speed rotary disc centrifugal atomization), the water jet velocity for water atomization was 8... The high-speed rotating disk for centrifugal atomization has a rotation speed of 13000 r / min, and the average particle size of the fine spherical amorphous powder is 100~150 mesh. Three types of amorphous powder were placed in acetone solution in batches and washed with an ultrasonic cleaner for 10 min to remove grease from the surface of the amorphous powder. Finally, the acetone solution was discarded and the powder was dried. Select first near-circular lamellar amorphous powder, second near-circular lamellar amorphous powder, and fine spherical amorphous powder of different masses, with a mass ratio of 5:4:1, and perform the following steps in sequence; Step 3: Phosphating Treatment: First near-circular lamellar amorphous powder is added to a first phosphate acetone solution. After stirring until the acetone completely evaporates, a phosphate layer forms on the surface of the first near-circular lamellar amorphous powder. Second near-circular lamellar amorphous powder is added to a second phosphate acetone solution. After stirring until the acetone completely evaporates, a phosphate layer forms on the surface of the second near-circular lamellar amorphous powder. The mass concentrations of the first and second phosphate acetone solutions are 4.5% and 6%, respectively, and the mass ratio of the first phosphate acetone solution to the first near-circular lamellar amorphous powder and the mass ratio of the second phosphate acetone solution to the second near-circular lamellar amorphous powder are 1:150. Then, fine spherical amorphous powder is added to the phosphate acetone solution. After stirring until the acetone completely evaporates, a phosphate layer forms on the surface of the fine spherical amorphous powder. The mass concentration of the phosphate acetone solution is 3%, and the mass ratio of the phosphate acetone solution to the fine spherical amorphous powder is 1:200. Phosphating-treated amorphous powder is obtained through these three processes. Step 4: Silane Coupling Treatment: Add the coupling agent (specifically KH550 coupling agent) to a 95% ethanol aqueous solution and stir until homogeneous. The mass ratio of coupling agent to ethanol aqueous solution is 1:130. Add sodium hydroxide to control the pH of the solution to alkaline (pH=9). Allow the coupling agent to fully hydrolyze under alkaline conditions for 20 min to obtain a coupling agent solution. Then add phosphating-treated amorphous powder. The mass ratio of phosphating-treated amorphous powder to coupling agent solution is 1:1.2. Stir for 1 hour, then discard the solution. Wash the remaining amorphous powder twice with alcohol, and finally dry it at 65℃ for 1 hour to obtain the coupling-treated amorphous powder. Step 5: Ferrite Coating: Dissolve Mn-Zn ferrite powder in an ethanol solution with a concentration of 0.0001 g / mL. Mix the coupled amorphous powder with a mixture of epoxy resin and acetone solution until homogeneous. The mass ratio of ferrite powder to coupled amorphous powder is 1:10. Mix the two evenly and stir for 1 hour. After high-temperature drying, obtain ferrite-coated amorphous powder (including ferrite-coated first nearly circular lamellar amorphous powder, ferrite-coated second nearly circular lamellar amorphous powder, and ferrite-coated fine spherical amorphous powder). Step 6: Organic layer coating. First, mix the first nearly circular lamellar amorphous powder coated with ferrite and the second nearly circular lamellar amorphous powder coated with ferrite evenly. Then, add the fine spherical amorphous powder coated with ferrite and mix further. Then, add it to an acetone solution of epoxy resin, phenolic resin and silicone resin. The mass ratio of epoxy resin, phenolic resin and silicone resin is 0.5:2:6.5. The mass ratio of organic resin (i.e., the mixture of epoxy resin, phenolic resin and silicone resin) to ferrite-coated amorphous powder is 1:30. The organic resin acetone solution must completely cover the surface of the magnetic powder. Stir slowly at 50 rpm until the acetone is completely evaporated. Step 7: Hot pressing-crystallization integrated molding: The amorphous powder coated on the surface is mixed with sodium silicate and barium stearate and placed in a mold. Under a high-purity argon protective atmosphere, the pressure is first gradually increased to 200 MPa at room temperature, with a pressure loading rate of 10 MPa / min, and held for 10 min (referred to as stage one). After holding the pressure, the pressure is further increased to 800 MPa at a pressure loading rate of 10 MPa / min, and held for 30 min at a holding temperature of 270 ℃ (referred to as stage two). After holding the pressure, the pressure is gradually decreased to 50 MPa at a pressure unloading rate of 50 MPa / s, and held for 10 min at a holding temperature of 520 ℃ (referred to as stage three). After holding the pressure, the pressure is increased again to 400 MPa at a pressure loading rate of 20 MPa / min, and held for 5 min, with the temperature gradually decreasing to room temperature during the pressure loading process (referred to as stage four), thus obtaining the nanocrystalline magnetic powder core matrix.

[0032] Step 8: Aging heat treatment: Place the nanocrystalline magnetic powder core substrate into an annealing furnace, raise the temperature to 100 ℃ under an argon protective atmosphere, raise the temperature at a rate of 10 ℃ / min, hold for 80 min, and after holding, cool with the furnace to 80 ℃ and then air cool to room temperature to obtain the high magnetic induction and ultra-high magnetic permeability iron-based nanocrystalline magnetic powder core.

[0033] Example 2 The only difference between this embodiment and Embodiment 1 is that the composition of the iron-based amorphous master alloy strip in step 1 is Fe. 0.781 Ni 0.042 B 0.093 P 0.037 C 0.004 Nb 0.013 Mo 0.022 Cu 0.008 In the twin-roll thin strip casting process, the roller speed is 4 m / s, and the resulting second iron-based amorphous master alloy strip has a casting strip width of 50 mm and a thickness of 180 μm; in the single-roll melt quenching process, the roller speed is 30 m / s, and the resulting first iron-based amorphous master alloy strip has a casting strip width of 80 mm and a thickness of 25 μm.

[0034] In step 2, when ball milling is performed on the first iron-based amorphous master alloy strip as raw material, the process conditions for ball milling of the first iron-based amorphous master alloy strip are: ball mill speed of 1900 r / min and ball milling time of 3 hours; the process conditions for ball milling of the second iron-based amorphous master alloy strip are: ball mill speed of 1400 r / min and ball milling time of 3 hours; in the multi-stage pulverization and atomization process (including water atomization and high-speed rotating disc centrifugal atomization), the water jet velocity for water atomization is 10 m / s, and the high-speed rotating disc speed for high-speed rotating disc centrifugal atomization is 17000 r / min; In step 3, the mass ratio of the first phosphate acetone solution to the first near-circular lamellar amorphous powder and the mass ratio of the second phosphate acetone solution to the second near-circular lamellar amorphous powder are 1:300; the mass ratio of the phosphate acetone solution to the fine spherical amorphous powder is 1:700. In step 4, the mass ratio of coupling agent to ethanol aqueous solution is 1:175. Hydrochloric acid is added to the coupling agent and ethanol aqueous solution to control the pH of the solution to be acidic (pH=6). The mass ratio of phosphating-treated amorphous powder to coupling agent solution is 1:1.7. In step 5, Ni-Zn ferrite powder is dissolved in an ethanol solution. The concentration of Ni-Zn ferrite in the ethanol solution is 0.001 g / mL, and the mass ratio of ferrite powder to coupling-treated amorphous powder is 1:20. In step 6, the mass ratio of epoxy resin, phenolic resin and silicone resin is 2:4:5.5, and the mass ratio of organic resin (i.e., the mixture of epoxy resin, phenolic resin and silicone resin) to ferrite-coated amorphous powder is 1:100. In step 7, the first stage pressure is 280 MPa, held for 20 min; the second stage pressure is 900 MPa, held for 40 min, and held at 310 ℃; the third stage pressure is reduced to 70 MPa, held for 15 min, and held at 540 ℃; and the fourth stage pressure is 500 MPa, held for 10 min. In step 8, the aging heat treatment temperature is 180 ℃ and the holding time is 210 min.

[0035] Example 3 The only difference between this embodiment and Embodiment 1 is that the composition of the iron-based amorphous master alloy strip in step 1 is Fe. 0.793 Co 0.004 B 0.145 P 0.001 Zr 0.045 Cu 0.003 In the twin-roll thin strip casting process, the roller speed is 8 m / s, and the resulting second iron-based amorphous master alloy strip has a casting width of 80 mm and a thickness of 120 μm. In the single-roll melt quenching process, the roller speed is 40 m / s, and the resulting first iron-based amorphous master alloy strip has a casting width of 120 mm and a thickness of 20 μm.

[0036] In step 2, when the first iron-based amorphous master alloy strip is used as raw material for ball milling, the process conditions for ball milling of the first iron-based amorphous master alloy strip are: ball mill speed of 2000 r / min and ball milling time of 2 hours; the process conditions for ball milling of the second iron-based amorphous master alloy strip are: ball mill speed of 1500 r / min and ball milling time of 1 hour; in the multi-stage pulverization and atomization process (including water atomization and high-speed rotating disc centrifugal atomization), the water jet velocity of water atomization is 12 m / s, and the high-speed rotating disc speed of high-speed rotating disc centrifugal atomization is 22000 r / min; In step 3, the mass ratio of the first phosphate acetone solution to the first near-circular lamellar amorphous powder and the mass ratio of the second phosphate acetone solution to the second near-circular lamellar amorphous powder are 1:500; the mass ratio of the phosphate acetone solution to the micro-spherical amorphous powder is 1:1200. In step 4, the mass ratio of coupling agent to ethanol aqueous solution is 1:200, the coupling agent and ethanol aqueous solution are neutral (pH=7), and the mass ratio of phosphating-treated amorphous powder to coupling agent solution is 1:2.4. In step 5, Co ferrite powder is dissolved in an ethanol solution. The concentration of Co ferrite in the ethanol solution is 0.01 g / mL, and the mass ratio of ferrite powder to coupling-treated amorphous powder is 1:30. In step 6, the mass ratio of epoxy resin, phenolic resin and silicone resin is 3.5:5:6.5, and the mass ratio of organic resin (i.e., a mixture of epoxy resin, phenolic resin and silicone resin) to ferrite-coated amorphous powder is 1:300. In step 7, the first stage pressure is 400 MPa, held for 30 min; the second stage pressure is 1200 MPa, held for 60 min, and held at 320 ℃; the third stage pressure is reduced to 100 MPa, held for 20 min, and held at 570 ℃; the fourth stage pressure is 600 MPa, held for 20 min. In step 8, the aging heat treatment temperature is 300 ℃ and the holding time is 240 min.

[0037] Example 4 The only difference between this embodiment and Embodiment 1 is that the composition of the iron-based amorphous master alloy strip in step 1 is Fe. 0.845 Co 0.005 B 0.105 P 0.005 Nb 0.025 Cu 0.02 In the twin-roll thin strip casting and rolling process, the roller speed is 4 m / s, and the resulting second iron-based amorphous master alloy strip has a casting strip width of 50 mm and a thickness of 180 μm; in the single-roll melt spin quenching process, the roller speed is 30 m / s, and the resulting first iron-based amorphous master alloy strip has a casting strip width of 80 mm and a thickness of 25 μm.

[0038] In step 2, when ball milling is performed on the first iron-based amorphous master alloy strip as raw material, the process conditions for ball milling of the first iron-based amorphous master alloy strip are: ball mill speed of 1900 r / min and ball milling time of 3 hours; the process conditions for ball milling of the second iron-based amorphous master alloy strip are: ball mill speed of 1400 r / min and ball milling time of 3 hours; in the multi-stage pulverization and atomization process (including water atomization and high-speed rotating disc centrifugal atomization), the water jet velocity for water atomization is 10 m / s, and the high-speed rotating disc speed for high-speed rotating disc centrifugal atomization is 17000 r / min; In step 3, the mass ratio of the first phosphate acetone solution to the first near-circular lamellar amorphous powder and the mass ratio of the second phosphate acetone solution to the second near-circular lamellar amorphous powder are 1:300; the mass ratio of the phosphate acetone solution to the fine spherical amorphous powder is 1:700. In step 4, the mass ratio of coupling agent to ethanol aqueous solution is 1:175. Hydrochloric acid is added to the coupling agent and ethanol aqueous solution to control the pH of the solution to be acidic (pH=6). The mass ratio of phosphating-treated amorphous powder to coupling agent solution is 1:1.7. In step 5, Ni ferrite powder is dissolved in an ethanol solution. The concentration of Ni ferrite in the ethanol solution is 0.001 g / mL, and the mass ratio of ferrite powder to coupling-treated amorphous powder is 1:20. In step 6, the mass ratio of epoxy resin, phenolic resin and silicone resin is 2:4:5.5, and the mass ratio of organic resin (i.e., the mixture of epoxy resin, phenolic resin and silicone resin) to ferrite-coated amorphous powder is 1:100. In step 7, the first stage pressure is 280 MPa, held for 20 min; the second stage pressure is 900 MPa, held for 40 min, and held at 310 ℃; the third stage pressure is reduced to 70 MPa, held for 15 min, and held at 540 ℃; and the fourth stage pressure is 500 MPa, held for 10 min. In step 8, the aging heat treatment temperature is 180 ℃ and the holding time is 210 min.

[0039] Example 5 The only difference between this embodiment and Embodiment 1 is that the composition of the iron-based amorphous master alloy strip in step 1 is Fe. 0.81 Co 0.027 B 0.106 P 0.028 Mn 0.019 Cu 0.01In the twin-roll thin strip casting and rolling process, the roller speed is 4 m / s, and the resulting second iron-based amorphous master alloy strip has a casting strip width of 50 mm and a thickness of 180 μm; in the single-roll melt spin quenching process, the roller speed is 30 m / s, and the resulting first iron-based amorphous master alloy strip has a casting strip width of 80 mm and a thickness of 25 μm.

[0040] In step 2, when ball milling is performed on the first iron-based amorphous master alloy strip as raw material, the process conditions for ball milling of the first iron-based amorphous master alloy strip are: ball mill speed of 1900 r / min and ball milling time of 3 hours; the process conditions for ball milling of the second iron-based amorphous master alloy strip are: ball mill speed of 1400 r / min and ball milling time of 3 hours; in the multi-stage pulverization and atomization process (including water atomization and high-speed rotating disc centrifugal atomization), the water jet velocity for water atomization is 10 m / s, and the high-speed rotating disc speed for high-speed rotating disc centrifugal atomization is 17000 r / min; In step 3, the mass ratio of the first phosphate acetone solution to the first near-circular lamellar amorphous powder and the mass ratio of the second phosphate acetone solution to the second near-circular lamellar amorphous powder are 1:300; the mass ratio of the phosphate acetone solution to the fine spherical amorphous powder is 1:700. In step 4, the mass ratio of coupling agent to ethanol aqueous solution is 1:175. Hydrochloric acid is added to the coupling agent and ethanol aqueous solution to control the pH of the solution to be acidic (pH=6). The mass ratio of phosphating-treated amorphous powder to coupling agent solution is 1:1.7. In step 5, Ni ferrite powder is dissolved in an ethanol solution. The concentration of Ni ferrite in the ethanol solution is 0.001 g / mL, and the mass ratio of ferrite powder to coupling-treated amorphous powder is 1:20. In step 6, the mass ratio of epoxy resin, phenolic resin and silicone resin is 2:4:5.5, and the mass ratio of organic resin (i.e., the mixture of epoxy resin, phenolic resin and silicone resin) to ferrite-coated amorphous powder is 1:100. In step 7, the first stage pressure is 280 MPa, held for 20 min; the second stage pressure is 900 MPa, held for 40 min, and held at 310 ℃; the third stage pressure is reduced to 70 MPa, held for 15 min, and held at 540 ℃; and the fourth stage pressure is 500 MPa, held for 10 min. In step 8, the aging heat treatment temperature is 180 ℃ and the holding time is 210 min.

[0041] Comparative Example 1 The only difference between this embodiment and Embodiment 1 is that the composition of the iron-based amorphous master alloy strip in step 1 is Fe. 0.78 Co 0.037 B 0.086 P 0.048Mn 0.029 Cu 0.02 ; In step 2, when ball milling is performed on the first iron-based amorphous master alloy strip as raw material, the process conditions for ball milling of the first iron-based amorphous master alloy strip are: ball mill speed of 3000 r / min and ball milling time of 0.5 hours; the process conditions for ball milling of the second iron-based amorphous master alloy strip are: ball mill speed of 2000 r / min and ball milling time of 1 hour; in the multi-stage pulverization and atomization process (including water atomization and high-speed rotating disc centrifugal atomization), the water jet velocity for water atomization is 20 m / s, and the high-speed rotating disc speed for high-speed rotating disc centrifugal atomization is 23000 r / min; In step 5, Ni-Zn ferrite powder is dissolved in an ethanol solution. The concentration of Ni-Zn ferrite in the ethanol solution is 0.001 g / mL, and the mass ratio of ferrite powder to coupling-treated amorphous powder is 1:20. In step 7, the first stage pressure is 280 MPa, held for 20 min; the second stage pressure is 900 MPa, held for 40 min, and held at 310 ℃; the third stage pressure is reduced to 70 MPa, held for 15 min, and held at 540 ℃; and the fourth stage pressure is 500 MPa, held for 10 min. In step 8, the aging heat treatment temperature is 180 ℃ and the holding time is 210 min.

[0042] Comparative Example 2 The only difference between this embodiment and Embodiment 1 is that the composition of the iron-based amorphous master alloy strip in step 1 is Fe. 0.86 Ni 0.007 B 0.061 P 0.038 Mn 0.009 Ga 0.015 Cu 0.01 ; In step 2, when the first iron-based amorphous master alloy strip is used as raw material for ball milling, the process conditions for ball milling of the first iron-based amorphous master alloy strip are: ball mill speed of 1000 r / min and ball milling time of 6 hours; the process conditions for ball milling of the second iron-based amorphous master alloy strip are: ball mill speed of 800 r / min and ball milling time of 5 hours; in the multi-stage pulverization and atomization process (including water atomization and high-speed rotating disc centrifugal atomization), the water jet velocity of water atomization is 3 m / s, and the high-speed rotating disc speed of high-speed rotating disc centrifugal atomization is 20000 r / min; In step 4, the mass ratio of coupling agent to ethanol aqueous solution is 1:80. Hydrochloric acid is added to the coupling agent and ethanol aqueous solution to control the pH of the solution to be acidic (pH=6). The mass ratio of phosphating-treated amorphous powder to coupling agent solution is 1:2.2. In step 6, the mass ratio of epoxy resin, phenolic resin and silicone resin is 1:5:9, and the mass ratio of organic resin to magnetic powder is 1:180. In step 8, the aging heat treatment temperature is 240 ℃ and the holding time is 900 min.

[0043] The permeability and saturation magnetic induction of the iron-based nanocrystalline soft magnetic powder cores described in Examples 1-5 and Comparative Examples 1-2 were measured using a BH analyzer. The test results are shown in Table 1 below.

[0044] Table 1

[0045] From Table 1, Figure 1 and Figure 2 It can be seen that the permeability of the iron-based nanocrystalline magnetic powder cores described in Examples 1-5 is all >82, and the saturation magnetic induction intensity is all >1.42T, which have the advantages of high permeability and high saturation magnetic induction intensity. However, the process parameters of Comparative Example 1 in the preparation of nanocrystalline magnetic powder are beyond the range of the present invention, resulting in low powder packing density and a permeability <65. In Comparative Example 2, the Fe content in the alloy composition used in the insulation coating process is much higher than the optimal range of the present invention, which leads to crystallization in the iron-based nanocrystalline magnetic powder core, resulting in deterioration of the soft magnetic properties of the magnetic powder core, with a saturation magnetic induction intensity <1.15T and a permeability of only 45.2, which is significantly different from the examples.

[0046] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A preparation process for a high magnetic induction and ultra-high magnetic permeability iron-based nanocrystalline magnetic powder core, characterized in that, Includes the following steps: Iron-based amorphous master alloy strip is prepared, wherein the composition of the iron-based amorphous master alloy strip is: Fe a M b X c Y d Cu e Where M is one or more of Co and Ni, X is one or more of B, Si, P, and C, and Y is one or more of Nb, Zr, Ga, Mn, and Mo. In terms of atomic percentage, 61.2%≤a≤84.7%, 0≤b≤9.7%, 3.7%≤c≤20.8%, 0≤d≤7.2%, 0.3%≤e≤2.1%, and a+b+c+d+e=100%; Based on the iron-based amorphous master alloy strip, lamellar amorphous powders and micro-spherical amorphous powders of different thicknesses were prepared. Different thicknesses of lamellar amorphous powder and micro-spherical amorphous powder are selected in proportion and coated multiple times in multiple levels to obtain amorphous powder with a coating layer on the surface. The coating layer includes a phosphating layer, a silane coupling layer, a ferrite layer and an organic layer from the inside out. Amorphous powder with a coating layer on the surface, binder and release agent are mixed and pressed into shape under vacuum or inert gas protective atmosphere to obtain nanocrystalline magnetic powder core matrix; The nanocrystalline magnetic powder core matrix is ​​subjected to aging heat treatment in a protective gas atmosphere to obtain a high magnetic induction and ultra-high magnetic permeability iron-based nanocrystalline magnetic powder core.

2. The preparation process of a high magnetic induction and ultra-high magnetic permeability iron-based nanocrystalline magnetic powder core according to claim 1, characterized in that, In the iron-based amorphous master alloy strip: 75.5%≤a≤84.5%； And / or, 0.1% ≤ b ≤ 6.4%; And / or, 8.7% ≤ c ≤ 14.5%; And / or, 0.1% ≤ d ≤ 4.5%; And / or, 0.5%≤e≤2.0%.

3. The preparation process of a high magnetic induction and ultra-high magnetic permeability iron-based nanocrystalline magnetic powder core according to claim 1, characterized in that, The preparation of the iron-based amorphous master alloy strip specifically involves: A master alloy ingot is melted by vacuum suspension melting to obtain a master alloy melt. Based on the master alloy melt, a first iron-based amorphous master alloy strip and a second iron-based amorphous master alloy strip are prepared by single-roll melt quenching process and double-roll thin strip casting and rolling process, respectively. In the single-roll melt quenching process, the roller speed is 20~40 m / s, and the resulting first iron-based amorphous master alloy strip has a casting strip width of 40~120 mm and a thickness of 20~30 μm; in the twin-roll thin strip casting and rolling process, the roller speed is 2~8 m / s, and the resulting second iron-based amorphous master alloy strip has a casting strip width of 30~80 mm and a thickness of 120~240 μm.

4. The preparation process of a high magnetic induction and ultra-high magnetic permeability iron-based nanocrystalline magnetic powder core according to claim 3, characterized in that, The preparation of lamellar amorphous powders and micro-spherical amorphous powders of different thicknesses based on the iron-based amorphous master alloy strip is specifically as follows: The lamellar amorphous powder is obtained by ball milling using first iron-based amorphous master alloy strip and second iron-based amorphous master alloy strip as raw materials. Specifically, using the first iron-based amorphous master alloy strip as raw material, the ball milling process conditions are: ball-to-material ratio of 6:1, ball milling speed of 1800~2000 r / min, ball milling time of 2~5h, and the thickness of the obtained first near-circular lamellar amorphous powder is ≤22μm and the diameter is ≤55μm. Using the second iron-based amorphous master alloy strip as raw material, the ball milling process conditions are: ball-to-material ratio of 4:1, ball milling speed of 1300~1500 r / min, ball milling time of 1~4h, and the thickness of the obtained second near-circular lamellar amorphous powder is ≤130 μm and the diameter is ≤75 μm. The fine spherical amorphous powder is obtained by multi-stage pulverization and atomization using industrial-grade Fe, M, X, Y and Cu as raw materials. The multi-stage pulverization and atomization includes water atomization and high-speed rotating disc centrifugal atomization. Specifically, the water jet velocity during the water atomization process is 8~12 m / s, the rotation speed of the high-speed turntable during the high-speed turntable centrifugal atomization process is 13000~22000 r / min, and the average particle size range of the resulting fine spherical amorphous powder is 100~150 mesh.

5. The preparation process of a high magnetic induction and ultra-high magnetic permeability iron-based nanocrystalline magnetic powder core according to claim 3, characterized in that, Different thicknesses of lamellar amorphous powder and fine spherical amorphous powder are selected in proportion and subjected to multiple multi-level coating processes. Specifically: Select first near-circular lamellar amorphous powder, second near-circular lamellar amorphous powder, and micro-spherical amorphous powder in a mass ratio of 5:4:1, and coat them sequentially with a phosphating layer, a silane coupling layer, a ferrite layer, and an organic layer to obtain amorphous powder with a coating layer on the surface.

6. The preparation process of a high magnetic induction and ultra-high magnetic permeability iron-based nanocrystalline magnetic powder core according to claim 5, characterized in that, The coating process of the phosphating layer is as follows: A first near-circular lamellar amorphous powder is added to a first phosphate acetone solution, and stirred until the acetone completely evaporates, forming a phosphate layer on the surface of the first near-circular lamellar amorphous powder. A second near-circular lamellar amorphous powder is added to a second phosphate acetone solution, and stirred until the acetone completely evaporates, forming a phosphate layer on the surface of the second near-circular lamellar amorphous powder. A fine spherical amorphous powder is added to a phosphate acetone solution, and stirred until the acetone completely evaporates, forming a phosphate layer on the surface of the fine spherical amorphous powder, thus obtaining a phosphate-treated amorphous powder. The mass concentration of the first phosphate acetone solution is 4.5%, the mass concentration of the second phosphate acetone solution is 6%, and the mass ratio of the first phosphate acetone solution to the first near-circular lamellar amorphous powder and the mass ratio of the second phosphate acetone solution to the second near-circular lamellar amorphous powder is 1:(150~500); the mass concentration of the phosphate acetone solution is 3%, and the mass ratio of the phosphate acetone solution to the micro-fine spherical amorphous powder is 1:(200~1200). The coating process of the silane coupling layer is as follows: Add the coupling agent to an ethanol aqueous solution and stir until homogeneous. Adjust the pH and wait for the coupling agent to be fully hydrolyzed to obtain a coupling agent solution. Add the phosphating-treated amorphous powder to the coupling agent solution, stir thoroughly, pour off the solution, wash with ethanol solution, and dry to obtain the coupling-treated amorphous powder. The volume concentration of the ethanol aqueous solution is 95%; the mass ratio of the coupling agent to the ethanol aqueous solution is 1:(130~200); the pH adjustment specifically involves adjusting the pH to 8~11; and the mass ratio of the phosphating-treated amorphous powder to the coupling agent solution is 1:(1.2~2.4).

7. The preparation process of a high magnetic induction and ultra-high magnetic permeability iron-based nanocrystalline magnetic powder core according to claim 6, characterized in that, The coating process of the ferrite layer is as follows: Ferrite powder is dissolved in ethanol or acetone to obtain mixed solution A. Then, the coupled amorphous powder is stirred evenly with a mixture of epoxy resin and acetone to obtain mixed solution B. Mixed solution A and mixed solution B are mixed evenly and then dried at high temperature to obtain ferrite-coated amorphous powder. The ferrite powder is Mn-Zn ferrite, Ni-Zn ferrite, Co ferrite, or Ni ferrite; the concentration of the ferrite powder in the ethanol or acetone solution is 0.0001~0.01 g / mL; the mass ratio of the ferrite powder to the coupled amorphous powder is 1:(10~30); the amount of epoxy resin added in mixed solution B is 3%~7% of the mass of the amorphous powder, and the concentration of the amorphous powder in the acetone solution is 0.0001~0.01 g / mL; the volume ratio of solution A to solution B is 1:(0.8~1.2). The coating process of the organic layer is as follows: After mixing the ferrite-coated amorphous powder, add it to an acetone solution of epoxy resin, phenolic resin and silicone resin, so that the acetone solution of epoxy resin, phenolic resin and silicone resin completely covers the ferrite-coated amorphous powder. Stir until the acetone completely evaporates to obtain an amorphous powder with a coating layer on the surface. The mass ratio of epoxy resin, phenolic resin and silicone resin is (0.5~3.5):(1.5~5):(2.5~6.5), the mass ratio of organic resin to ferrite-coated amorphous powder is 1:(30~300), the concentration of ferrite-coated amorphous powder in acetone solution is 0.0001~0.01 g / mL, and the organic resin is epoxy resin, phenolic resin and silicone resin.

8. The preparation process of a high magnetic induction and ultra-high magnetic permeability iron-based nanocrystalline magnetic powder core according to claim 1, characterized in that, Amorphous powder with a surface coating, binder, and release agent are mixed and pressed into shape under vacuum or inert gas protection atmosphere to obtain a nanocrystalline magnetic powder core matrix. The specific process is as follows: Amorphous powder with a surface coating, along with a binder and a release agent, is placed in a mold. First, the pressure is gradually increased to 200–400 MPa at room temperature, with a pressure loading rate of 10 MPa / min, and held for 10–30 min. After holding, the pressure is further increased to 800–1200 MPa at a pressure loading rate of 10 MPa / min, and held for 30–60 min at a holding temperature of 270–320℃. After holding, the pressure is gradually decreased to 50–100 MPa at a pressure unloading rate of 50 MPa / s, and held for 10–20 min at a holding temperature of 520–570℃. After holding, the pressure is increased again to 400–600 MPa at a pressure loading rate of 20 MPa / min, and held for 5–20 min, with the temperature gradually decreasing to room temperature during the pressure loading process, thus obtaining a nanocrystalline magnetic powder core matrix.

9. The preparation process of a high magnetic induction and ultra-high magnetic permeability iron-based nanocrystalline magnetic powder core according to claim 1, characterized in that, The aging heat treatment temperature is 100~300℃, and the holding time is 30~240 min.

10. A high-magnetic-induction, ultra-high-permeability iron-based nanocrystalline magnetic powder core, characterized in that, It is prepared by the preparation process described in any one of claims 1-9.

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