Preparation method of magnetically soft alloy magnetic powder core and magnetic powder core

Abstract

The invention provides a preparation method of a magnetically soft alloy magnetic powder core and the magnetically soft alloy magnetic powder core. The preparation method comprises the steps that a nickel ingot and an iron ingot are smelted, magnesium steam is introduced, and magnetically soft alloy raw powder is prepared in a gas atomization mode; acetic acid, an additive and the soft magnetic alloy raw powder are mixed, so that a coating layer is formed on the outer surface of the soft magnetic alloy raw powder, iron-nickel magnetic powder is obtained, then the iron-nickel magnetic powder is pressed, and the magnetic powder core is obtained. The method is easy to operate, the process is controllable, and the magnetic powder core with high magnetic conductivity, high resistivity and low loss can be obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of soft magnetic materials, and relates to a preparation method of a soft magnetic alloy magnetic powder core and the magnetic powder core. Background Art

[0002] Soft magnetic composite materials combine the advantages of metallic and ferrite soft magnetic materials. Their resistivity is significantly increased compared with soft magnetic metals, which can effectively reduce eddy current losses. Moreover, compared with soft magnetic ferrites, soft magnetic composite materials have a higher saturation magnetization intensity, and can better meet the requirements of miniaturization and integration of power electronic devices. Soft magnetic composite materials can be pressed into various complex shapes to realize integrated production of components. At present, soft magnetic composite materials have become the magnetic materials with the fastest growth rate in development and application, and are used to produce various key power electronic components such as inductors, filters, chokes and transformers.

[0003] Soft magnetic alloy magnetic powders include various metallic ferromagnetic powders such as FeNi alloy systems, FeSi alloy systems, FeSiAl alloy systems, amorphous and nanocrystalline alloys, etc. Before preparing devices, in order to explore the performance characteristics of the magnetic powders, the magnetic powders need to be first pressed into a ring-shaped block structure with a fixed size, called a magnetic powder core, and parameters such as the electromagnetic characteristics and mechanical strength of the magnetic powder core are studied.

[0004] Metal soft magnetic magnetic powder cores are a kind of soft magnetic functional materials obtained by using alloy powders as raw powders, coating insulating materials on the surfaces of the magnetic powders, and then through pressing and heat treatment annealing. With the trend of high frequency of electronic devices, the demand for excellent properties such as high magnetic permeability and low loss of metal magnetic powder cores has become an inevitable trend.

[0005] CN109754972A discloses a soft magnetic powder material for high-frequency molded inductors and its preparation method. By mutually proportioning metal soft magnetic powders of different particle sizes and different types, which can be any one or a mixture of iron-silicon-chromium alloy powder, carbonyl iron powder, iron-silicon-aluminum alloy powder, iron-nickel alloy powder, and iron-silicon alloy powder, acid passivation is used, and a mixed powder of silica powder, magnesium silicate, and talc powder is used for insulation, resin bonding, and finally lubricating powder is added to obtain the soft magnetic powder material. Through sufficient insulation with inorganic compounds after passivation, the obtained soft magnetic inductor has a high resistivity and low loss, but excessive coating easily leads to a low effective magnetic permeability of the magnetic powder core. CN107578874A discloses a preparation method of an iron-nickel magnetic powder core with high magnetic permeability. First, a coating agent such as calcium oxide, kaolin, magnesium oxide, and organic glue is used for primary insulation coating, then annealing is carried out using a protective gas, then passivation is carried out using phosphoric acid, an insulating agent and an adhesive are added for secondary insulation coating, and finally a demolding agent is added, pressed into shape, the magnetic powder core blank is heat-treated in an atmosphere of nitrogen, hydrogen, or argon, and finally an epoxy resin paint is sprayed on the surface of the treated magnetic powder core to obtain the final product. The iron-nickel magnetic powder core of this invention has a high magnetic permeability, but physical coating of inorganic compounds easily leads to uneven coating layer thickness, resulting in a low resistivity, high loss, and poor DC superposition performance of the magnetic powder core. However, the magnetic powder core manufactured by the process flow designed by the above technical solutions has the characteristics of excellent single performance and poor overall performance, resulting in a narrow application range of the obtained magnetic powder core.

[0006] Therefore, how to obtain a magnetic powder core with high magnetic permeability and low loss to meet the requirements of different manufacturing fields is the current research direction that has received attention. Summary of the Invention

[0007] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a preparation method of a soft magnetic alloy magnetic powder core and the magnetic powder core. By improving the cleanliness of the metal powder, the effective magnetic components per unit volume are increased, and the coating method is improved to obtain a magnetic powder core with high magnetic permeability, high resistivity, and low loss. The process is controllable and can be applied to more electronic and electrical fields.

[0008] To achieve this purpose, the present invention adopts the following technical solutions:

[0009] In the first aspect, the present invention provides a preparation method of a soft magnetic alloy magnetic powder core, and the preparation method includes:

[0010] Melting a nickel ingot and an iron ingot, introducing magnesium vapor, and using a gas atomization method to make a soft magnetic alloy raw powder; mixing acetic acid, an additive, and the soft magnetic alloy raw powder to form a coating layer on the outer surface of the soft magnetic alloy raw powder to obtain an iron-nickel magnetic powder, and then performing a pressing treatment on the iron-nickel magnetic powder to obtain a magnetic powder core.

[0011] The preparation method provided by the present invention has the advantages of simple operation, easy implementation, strong controllability, etc. By introducing magnesium vapor during the smelting process, the non-metallic elements doped during the smelting and powder-making processes are effectively reduced, the powder cleanliness is improved, which is beneficial to enhancing the magnetic permeability of the magnetic powder core. Then, during the coating process, a weak acid is used to dissolve the magnesium compounds in the soft magnetic alloy raw powder, and iron-nickel magnetic powder uniformly coated with magnesium oxide is obtained through chemical action, reducing the loss and increasing the effective magnetic components per unit volume, so that the magnetic powder core has excellent soft magnetic properties such as high magnetic permeability, low loss, and high DC superposition.

[0012] Since nickel-iron alloy raw materials are prone to doping a small amount of non-metallic elements such as O, S, P, etc. inside the powder during the processes of smelting, powder-making, etc., and problems such as uneven coating layer thickness and poor consistency are likely to occur during the process of coating inorganic compounds, these problems will have an adverse impact on the performance of the magnetic powder core. Therefore, in the present invention, magnesium vapor is introduced during the smelting process. Relying on the strong activity of Mg itself and the strong affinity of Mg with impurity elements such as O and S, reactions occur to generate products such as MgO and MgS, which can reduce the influence of non-metallic elements on the soft magnetic alloy raw powder. Then, the soft magnetic alloy raw powder is mixed with acetic acid, and iron-nickel magnetic powder coated with magnesium acetate is obtained through chemical reaction, which is beneficial to reducing the loss of the raw powder.

[0013] It should be noted that the smelting in the present invention refers to the process of putting nickel ingots and iron ingots into a smelting furnace and melting the nickel ingots and iron ingots at a certain high temperature to form a nickel-iron alloy melt. The working principle of making the soft magnetic alloy raw powder by the gas atomization method in the present invention is as follows: using a rapidly moving atomization medium to impact the alloy liquid to break it into fine droplets, and then condensing them into solid powders. Specifically, in the present invention, the nickel-iron alloy melt after smelting is placed in an atomization device, and then an inert gas is sent into the atomization device at a predetermined pressure and temperature. Under the impact of the inert gas, the nickel-iron alloy melt is broken into fine droplets, and after cooling, it is taken out to obtain the soft magnetic alloy raw powder.

[0014] As a preferred technical solution of the present invention, the total mass of the nickel ingots and iron ingots is recorded as 100%, and the content of the nickel ingots is 46 - 54 wt%, and the rest is iron ingots.

[0015] Among them, the content of the nickel ingots can be 46%, 47%, 48%, 49%, 50 wt%, 51 wt%, 52 wt%, 53 wt% or 54 wt%, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0016] Preferably, the feeding amount of the magnesium vapor is 0.1-0.5 wt%, for example, it can be 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.35 wt%, 0.4 wt%, 0.45 wt% or 0.5%, but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0017] Preferably, the average particle size of the soft magnetic alloy raw powder is 10-30 μm, for example, it can be 10 μm, 12 μm, 15 μm, 16 μm, 18 μm, 20 μm, 22 μm, 25 μm, 26 μm, 28 μm or 30 μm, but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0018] As a preferred technical solution of the present invention, taking the mass of the soft magnetic alloy raw powder as 100%, the addition amount of acetic acid is 1-3 wt%, for example, it can be 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.5 wt%, 1.8 wt%, 2 wt%, 2.2 wt%, 2.4 wt%, 2.5 wt%, 2.8 wt% or 3%, but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0019] Preferably, the additive is absolute ethanol.

[0020] As a preferred technical solution of the present invention, the mixing includes: mixing acetic acid and the additive and stirring evenly, then adding the soft magnetic alloy raw powder for ball milling treatment, and then drying to obtain the iron-nickel magnetic powder.

[0021] Preferably, the time of the ball milling treatment is 1-3 h, for example, it can be 1 h, 1.2 h, 1.5 h, 1.8 h, 2 h, 2.3 h, 2.5 h, 2.8 h or 3 h, but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0022] As a preferred technical solution of the present invention, the preparation method further includes: annealing the iron-nickel magnetic powder in an inert atmosphere.

[0023] In the present invention, the soft magnetic alloy raw powder is put into ethanol dissolved with acetic acid for mixing, and through chemical action, the soft magnetic alloy raw powder coated with magnesium acetate is obtained, and then through annealing treatment, the iron-nickel magnetic powder uniformly coated with magnesium oxide is obtained.

[0024] Preferably, the temperature of the annealing treatment is 600 to 800 °C. For example, it can be 600 °C, 620 °C, 640 °C, 650 °C, 680 °C, 700 °C, 730 °C, 750 °C, 780 °C or 800 °C. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0025] Preferably, the time of the annealing treatment is 3 to 5 h. For example, it can be 3 h, 3.2 h, 3.5 h, 3.8 h, 4 h, 4.3 h, 4.5 h, 4.8 h or 5 h. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0026] As a preferred technical solution of the present invention, the preparation method further includes: after the annealing treatment is completed, drying the iron-nickel magnetic powder.

[0027] The drying treatment method includes: mixing a silane coupling agent, a resin binder and a solvent evenly, adding the iron-nickel magnetic powder after the annealing treatment, and performing a first stirring and a second stirring in sequence to volatilize the solvent.

[0028] Preferably, the temperature of the first stirring is 20 to 30 °C. For example, it can be 20 °C, 21 °C, 22 °C, 23 °C, 24 °C, 25 °C, 26 °C, 27 °C, 28 °C or 30 °C. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0029] Preferably, the time of the first stirring is 10 to 20 min. For example, it can be 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min or 20 min. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0030] Preferably, during the second stirring, the temperature of the iron-nickel magnetic powder is raised to 100 to 120 °C to volatilize the solvent.

[0031] The temperature of the temperature rise can be, for example, 100 °C, 102 °C, 105 °C, 106 °C, 108 °C, 110 °C, 113 °C, 115 °C, 118 °C or 120 °C. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0032] Preferably, the preparation method further includes: before the drying treatment, cooling and screening the iron-nickel magnetic powder after the annealing treatment.

[0033] As a preferred technical solution of the present invention, the mass of the annealed iron-nickel magnetic powder is denoted as 100%, and the addition amount of the silane coupling agent is 0.1-1 wt%, for example, it can be 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt% or 1 wt%, but is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0034] The addition amount of the resin binder is 1-3 wt%, for example, it can be 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.5 wt%, 1.8 wt%, 2 wt%, 2.2 wt%, 2.4 wt%, 2.5 wt%, 2.8 wt% or 3 wt%, but is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0035] Preferably, the silane coupling agent includes any one or a combination of at least two of an amino silane coupling agent, an epoxy silane coupling agent and a vinyl silane coupling agent. Typical but non-limiting combinations are: a combination of an amino silane coupling agent and an epoxy silane coupling agent, a combination of an epoxy silane coupling agent and a vinyl silane coupling agent, a combination of an amino silane coupling agent, an epoxy silane coupling agent and a vinyl silane coupling agent, a combination of an amino silane coupling agent and a vinyl silane coupling agent, and so on.

[0036] Preferably, the resin binder includes any one or a combination of at least two of an epoxy resin binder, a silicone resin binder and a phenolic resin binder. Typical but non-limiting combinations are: a combination of an epoxy resin binder and a silicone resin binder, a combination of a silicone resin binder and a phenolic resin binder, a combination of an epoxy resin binder and a phenolic resin binder, a combination of an epoxy resin binder, a silicone resin binder and a phenolic resin binder, and so on.

[0037] Preferably, the solvent includes ethanol and acetone.

[0038] Preferably, the mass of the annealed iron-nickel magnetic powder is denoted as 100%, and the addition amount of the ethanol is 5-7 wt%, for example, it can be 5 wt%, 5.3 wt%, 5.5 wt%, 5.8 wt%, 6 wt%, 6.2 wt%, 6.5 wt%, 6.6 wt%, 6.9 wt% or 7 wt%, but is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0039] The addition amount of the acetone is 12-18 wt%, for example, it can be 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt% or 18 wt%, but is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0040] In the present invention, a magnesium acetate coating layer is generated through a chemical reaction, and then a uniform magnesium oxide coating layer is obtained by one-step high-temperature annealing, which improves the properties of the magnetic powder, makes full use of energy, effectively increases the resistance of the magnetic powder core, and enables the prepared magnetic powder core to have excellent soft magnetic properties such as high magnetic permeability, low loss, and high DC superposition.

[0041] As a preferred technical solution of the present invention, the pressing treatment includes: uniformly mixing the iron-nickel magnetic powder and the mold release powder, then pressing and forming, and then performing heat treatment to obtain the magnetic powder core.

[0042] Preferably, the mass of the dried iron-nickel magnetic powder is recorded as 100%, and the addition amount of the mold release powder is 0.1-0.3 wt%, for example, it can be 0.1 wt%, 0.12 wt%, 0.15 wt%, 0.18 wt%, 0.2 wt%, 0.23 wt%, 0.25 wt%, 0.28 wt% or 0.3 wt%, but is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0043] Preferably, the mold release powder includes any one or a combination of at least two of zinc stearate powder, magnesium stearate powder, aluminum stearate powder, calcium stearate powder and graphite powder. Typical but non-limiting combinations are: the combination of zinc stearate powder and magnesium stearate powder, the combination of magnesium stearate powder and aluminum stearate powder, the combination of aluminum stearate powder, calcium stearate powder and graphite powder, the combination of zinc stearate powder, magnesium stearate powder and aluminum stearate powder, and so on.

[0044] Preferably, the pressure for pressing and forming is 1000-2000 MPa, for example, it can be 1000 MPa, 1100 MPa, 1200 MPa, 1300 MPa, 1400 MPa, 1500 MPa, 1600 MPa, 1700 MPa, 1800 MPa, 1900 MPa or 2000 MPa, but is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0045] Preferably, the heat treatment is carried out in a protective atmosphere or a reducing atmosphere.

[0046] Preferably, the temperature of the heat treatment is 600 to 800 °C. For example, it can be 600 °C, 620 °C, 630 °C, 650 °C, 680 °C, 700 °C, 730 °C, 750 °C, 780 °C or 800 °C. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0047] Preferably, the time of the heat treatment is 30 to 90 min. For example, it can be 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 70 min, 75 min, 80 min, 85 min or 90 min. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0048] As a preferred technical solution of the present invention, the preparation method specifically includes the following steps:

[0049] S1 Melting the nickel ingot and the iron ingot, introducing magnesium vapor, and making soft magnetic alloy raw powder by gas atomization method;

[0050] S2 Mixing acetic acid and additives and stirring evenly, adding the soft magnetic alloy raw powder in step S1 for ball milling and drying to form a coating layer on the outer surface of the soft magnetic alloy raw powder, obtaining iron-nickel magnetic powder, and then carrying out annealing treatment of the iron-nickel magnetic powder under an inert atmosphere;

[0051] S3 Mixing silane coupling agent, resin binder and solvent evenly, adding the iron-nickel magnetic powder after annealing treatment, and carrying out primary stirring and secondary stirring in sequence to volatilize the solvent and obtain dry iron-nickel magnetic powder;

[0052] S4 Mixing the dry iron-nickel magnetic powder in step S3 and the demolding powder evenly, pressing and molding, and then carrying out heat treatment to obtain the magnetic powder core.

[0053] In the second aspect, the present invention provides a magnetic powder core, and the magnetic powder core is prepared by using the preparation method described in the first aspect.

[0054] The magnetic powder core of the present invention has high cleanliness, high magnetic permeability and resistivity, low loss, and high soft magnetic properties, and can meet the requirements of various electronic and electrical fields.

[0055] The numerical range described in the present invention not only includes the above-listed point values, but also includes any point values between the above numerical ranges that are not listed. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the range.

[0056] Compared with the prior art, the beneficial effects of the present invention are:

[0057] A preparation method of a soft magnetic alloy powder core and the powder core provided by the present invention reduce the content of non-metallic elements in the alloy raw powder by introducing magnesium vapor, improve the powder cleanliness, and further enhance the effective magnetic components and magnetic permeability per unit volume. Then, during the coating process, weak acid is used to dissolve the magnesium compounds in the soft magnetic alloy raw powder to obtain iron-nickel magnetic powder uniformly coated with magnesium oxide, enabling the powder core to have excellent soft magnetic properties such as high magnetic permeability, low loss, and high DC superposition. The preparation method has the advantages of simple operation, easy implementation, and strong controllability. Detailed Embodiments

[0058] It should be understood that in the description of the present invention, terms such as "first time", "second time", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first time", "second time", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise stated, the meaning of "a plurality" is two or more.

[0059] The technical solutions of the present invention will be further described below through specific embodiments.

[0060] It should be noted that in step S1 involved in the following preparation process, the mass percentages of the nickel ingot, iron ingot, and magnesium vapor added are based on the total mass of the nickel ingot and iron ingot; in step S2, the mass percentage of the acetic acid added is based on the mass of the soft magnetic alloy raw powder in step S1; in step S3, the mass percentages of the silane coupling agent, resin binder, ethanol, and acetone added are all based on the mass of the iron-nickel magnetic powder after annealing treatment in step S2; in step S4, the mass percentage of the demolding powder added is based on the mass of the iron-nickel magnetic powder after drying treatment in step S3.

[0061] In a specific embodiment, the present invention provides a preparation method of a soft magnetic alloy powder core. The preparation method specifically includes the following steps:

[0062] S1: Melting 46 - 54 wt% of nickel ingot and 46% - 54 wt% of iron ingot, introducing 0.1 - 0.5 wt% of magnesium vapor, removing impurities, and then using gas atomization to make powder. After sieving, soft magnetic alloy raw powder with an average particle size of 10 - 30 μm is obtained;

[0063] S2: Mixing 1 - 3 wt% of acetic acid and sufficient anhydrous ethanol evenly, then adding the soft magnetic alloy raw powder of step S1, performing ball milling for 1 - 3 h and drying to form a coating layer on the outer surface of the soft magnetic alloy raw powder to obtain iron-nickel magnetic powder. Subsequently, in an inert atmosphere, the iron-nickel magnetic powder is placed in an annealing furnace at 600 - 800 °C for 3 - 5 h of annealing treatment, and then cooled and sieved in sequence;

[0064] S3 mixes 0.1 - 1 wt% of silane coupling agent, 1 - 3 wt% of resin binder, 5 - 7 wt% of ethanol and 12 - 18 wt% of acetone evenly, adds the sieved iron-nickel magnetic powder, and conducts a primary stirring for 10 - 20 min under the temperature condition of 20 - 30 °C. Then, while heating the iron-nickel magnetic powder to 100 - 120 °C, a secondary stirring is carried out to volatilize the solvent and obtain dry iron-nickel magnetic powder. Among them, the silane coupling agent includes any one or a combination of at least two of amino silane coupling agent, epoxy silane coupling agent and vinyl silane coupling agent; the resin binder includes any one or a combination of at least two of epoxy resin binder, silicone resin binder and phenolic resin binder;

[0065] S4 mixes 0.1 - 0.3 wt% of mold release powder with the sieved iron-nickel magnetic powder evenly, compresses and forms it under the condition of 1000 - 2000 MPa, and then conducts a heat treatment for 30 - 90 min under the temperature condition of 600 - 800 °C to obtain a magnetic powder core. Among them, the heat treatment is carried out in a protective atmosphere or a reducing atmosphere, and the mold release powder includes any one or a combination of at least two of zinc stearate powder, magnesium stearate powder, aluminum stearate powder, calcium stearate powder and graphite powder.

[0066] In another specific embodiment, the present invention provides a magnetic powder core, and the magnetic powder core is prepared by using the preparation method described in a specific embodiment. The magnetic powder core of the present invention has high cleanliness, and has relatively high magnetic permeability and resistivity, low loss, and relatively high soft magnetic properties, and can meet the requirements of various electronic and electrical fields.

[0067] Example 1

[0068] This example provides a preparation method of a soft magnetic alloy magnetic powder core, which specifically includes the following steps:

[0069] S1 melts 50 wt% of nickel ingot and 50 wt% of iron ingot, introduces 0.3 wt% of magnesium vapor, removes impurities, and then uses a gas atomization method to make powder. After sieving, soft magnetic alloy raw powder with an average particle size of 20 μm is obtained;

[0070] S2 adds 2 wt% of acetic acid and sufficient anhydrous ethanol into a ball milling tank, stirs evenly, adds the soft magnetic alloy raw powder obtained in step S1 to form a slurry, places the ball milling tank on a ball mill, conducts a ball milling treatment on the slurry for 2 h and dries it to form a coating layer on the outer surface of the soft magnetic alloy raw powder to obtain iron-nickel magnetic powder. Then, in an inert atmosphere, the iron-nickel magnetic powder is put into an annealing furnace at 700 °C for an annealing treatment for 4 h, and then cooling and sieving are carried out in sequence;

[0071] S3 mixes 0.5 wt% epoxy group silane coupling agent, 2 wt% silicone resin binder, 5 wt% ethanol and 15 wt% acetone evenly, adds the sieved iron-nickel magnetic powder, conducts primary stirring for 15 min at 25 °C, then heats the iron-nickel magnetic powder to 110 °C while conducting secondary stirring to volatilize the solvent and obtain dry iron-nickel magnetic powder;

[0072] S4 mixes 0.3 wt% zinc stearate release powder with the sieved iron-nickel magnetic powder evenly, compresses and forms it under the condition of 1500 MPa, and then conducts heat treatment at 700 °C for 60 min under a protective atmosphere to obtain the magnetic powder core.

[0073] Example 2

[0074] This example provides a preparation method of a soft magnetic alloy magnetic powder core, which specifically includes the following steps:

[0075] S1 melts 46 wt% nickel ingot and 54 wt% iron ingot, introduces 0.1 wt% magnesium vapor, removes impurities, and then makes powder by gas atomization method, and obtains soft magnetic alloy raw powder with an average particle size of 30 μm through sieving;

[0076] S2 adds 1 wt% acetic acid and sufficient anhydrous ethanol into the ball milling tank, stirs evenly, adds the soft magnetic alloy raw powder in step S1 to form a slurry, places the ball milling tank on the ball mill, conducts ball milling treatment on the slurry for 1 h and dries it to form a coating layer on the outer surface of the soft magnetic alloy raw powder to obtain iron-nickel magnetic powder, then places the iron-nickel magnetic powder in an annealing furnace at 800 °C for 3 h for annealing treatment under an inert atmosphere, and conducts cooling and sieving in sequence;

[0077] S3 mixes 0.1 wt% vinyl silane coupling agent, 1 wt% epoxy resin binder, 5 wt% ethanol and 15 wt% acetone evenly, adds the sieved iron-nickel magnetic powder, conducts primary stirring for 15 min at 25 °C, then heats the iron-nickel magnetic powder to 110 °C while conducting secondary stirring to volatilize the solvent and obtain dry iron-nickel magnetic powder;

[0078] S4 mixes 0.1 wt% zinc stearate release powder with the sieved iron-nickel magnetic powder evenly, compresses and forms it under the condition of 2000 MPa, and then conducts heat treatment at 800 °C for 30 min under a protective atmosphere to obtain the magnetic powder core.

[0079] Example 3

[0080] This example provides a preparation method of a soft magnetic alloy magnetic powder core, which specifically includes the following steps:

[0081] S1 Melting a 54 wt% nickel ingot and a 46 wt% iron ingot, introducing 0.5 wt% magnesium vapor, removing impurities, and then producing powder by gas atomization. After sieving, soft magnetic alloy raw powder with an average particle size of 10 μm is obtained;

[0082] S2 Adding 3 wt% acetic acid and sufficient absolute ethanol into a ball milling tank, stirring evenly, adding the soft magnetic alloy raw powder from step S1 to form a slurry, placing the ball milling tank on a ball mill, performing ball milling treatment on the slurry for 3 h and drying it to form a coating layer on the outer surface of the soft magnetic alloy raw powder, obtaining iron-nickel magnetic powder. Subsequently, in an inert atmosphere, putting the iron-nickel magnetic powder into an annealing furnace at 600 °C for 5 h of annealing treatment, and then performing cooling and sieving in sequence;

[0083] S3 Mixing 1 wt% amino silane coupling agent, 3 wt% phenolic resin binder, 5 wt% ethanol and 15 wt% acetone evenly, adding the sieved iron-nickel magnetic powder, performing a primary stirring at 25 °C for 15 min, and then while heating the iron-nickel magnetic powder to 110 °C, performing a secondary stirring to volatilize the solvent, obtaining dry iron-nickel magnetic powder;

[0084] S4 Mixing 0.5 wt% zinc stearate release powder and the sieved iron-nickel magnetic powder evenly, pressing and forming at 1000 MPa, and then performing heat treatment at 600 °C for 90 min in a protective atmosphere to obtain a magnetic powder core.

[0085] Example 4

[0086] This example provides a preparation method of a soft magnetic alloy magnetic powder core, specifically including the following steps:

[0087] S1 Melting a 48 wt% nickel ingot and a 52 wt% iron ingot, introducing 0.2 wt% magnesium vapor, removing impurities, and then producing powder by gas atomization. After sieving, soft magnetic alloy raw powder with an average particle size of 25 μm is obtained;

[0088] S2 Adding 2.5 wt% acetic acid and sufficient absolute ethanol into a ball milling tank, stirring evenly, adding the soft magnetic alloy raw powder from step S1 to form a slurry, placing the ball milling tank on a ball mill, performing ball milling treatment on the slurry for 1.5 h and drying it to form a coating layer on the outer surface of the soft magnetic alloy raw powder, obtaining iron-nickel magnetic powder. Subsequently, in an inert atmosphere, putting the iron-nickel magnetic powder into an annealing furnace at 650 °C for 5 h of annealing treatment, and then performing cooling and sieving in sequence;

[0089] S3 mixes 0.3 wt% of a combination of epoxy-based silane coupling agent and vinyl silane coupling agent, 2.5 wt% of silicone resin binder, 6 wt% of ethanol and 12 wt% of acetone evenly, adds the sieved iron-nickel magnetic powder, and conducts a first stirring for 20 min under the temperature condition of 20 °C. Then, while heating the iron-nickel magnetic powder to 120 °C, a second stirring is carried out to volatilize the solvent, obtaining dry iron-nickel magnetic powder;

[0090] S4 mixes 0.25 wt% of zinc stearate release agent and the sieved iron-nickel magnetic powder evenly, compresses and forms it under the condition of 1800 MPa, and then conducts a heat treatment at 650 °C for 50 min under a protective atmosphere to obtain a magnetic powder core.

[0091] Example 5

[0092] This example provides a preparation method of a soft magnetic alloy magnetic powder core, which specifically includes the following steps:

[0093] S1 melts 52 wt% of nickel ingots and 48 wt% of iron ingots, introduces 0.4 wt% of magnesium vapor, removes impurities, and then makes powder by gas atomization method. After sieving, soft magnetic alloy raw powder with an average particle size of 15 μm is obtained;

[0094] S2 adds 1.5 wt% of acetic acid and sufficient anhydrous ethanol into a ball milling tank, stirs evenly, adds the soft magnetic alloy raw powder in step S1 to form a slurry, places the ball milling tank on a ball mill, conducts ball milling treatment on the slurry for 2.5 h and dries it to form a coating layer on the outer surface of the soft magnetic alloy raw powder, obtaining iron-nickel magnetic powder. Then, under an inert atmosphere, the iron-nickel magnetic powder is put into an annealing furnace at 750 °C for 3.5 h of annealing treatment, and cooling and sieving are carried out in sequence;

[0095] S3 mixes 0.6 wt% of epoxy-based silane coupling agent, 1.5 wt% of silicone resin binder, 7 wt% of ethanol and 18 wt% of acetone evenly, adds the sieved iron-nickel magnetic powder, and conducts a first stirring for 10 min under the temperature condition of 30 °C. Then, while heating the iron-nickel magnetic powder to 110 °C, a second stirring is carried out to volatilize the solvent, obtaining dry iron-nickel magnetic powder;

[0096] S4 mixes a combination of 0.15 wt% of zinc stearate release agent and magnesium stearate powder, and the sieved iron-nickel magnetic powder evenly, compresses and forms it under the condition of 1300 MPa, and then conducts a heat treatment at 750 °C for 45 min under a protective atmosphere to obtain a magnetic powder core.

[0097] Example 6

[0098] This embodiment provides a method for preparing a soft magnetic alloy powder core, which is different from that of Embodiment 1 in that: in step S1, the input amount of magnesium vapor is 0.08 wt%, and the remaining operation steps and process parameters are the same as those in Embodiment 1.

[0099] Embodiment 7

[0100] This embodiment provides a method for preparing a soft magnetic alloy powder core, which is different from that of Embodiment 1 in that: in step S1, the input amount of magnesium vapor is 0.6 wt%, and the remaining operation steps and process parameters are the same as those in Embodiment 1.

[0101] Embodiment 8

[0102] This embodiment provides a method for preparing a soft magnetic alloy powder core, which is different from that of Embodiment 1 in that: in step S2, the added amount of acetic acid is 0.5 wt%, and the remaining operation steps and process parameters are the same as those in Embodiment 1.

[0103] Embodiment 9

[0104] This embodiment provides a method for preparing a soft magnetic alloy powder core, which is different from that of Embodiment 1 in that: in step S2, the added amount of acetic acid is 4 wt%, and the remaining operation steps and process parameters are the same as those in Embodiment 1.

[0105] Embodiment 10

[0106] This embodiment provides a method for preparing a soft magnetic alloy powder core, which is different from that of Embodiment 1 in that: in step S2, the slurry formed after adding the soft magnetic alloy raw powder is stirred and mixed, and no ball milling treatment is performed. The remaining operation steps and process parameters are the same as those in Embodiment 1.

[0107] Embodiment 11

[0108] This embodiment provides a method for preparing a soft magnetic alloy powder core, which is different from that of Embodiment 1 in that: in step S2, 2% acetic acid, sufficient absolute ethanol and the soft magnetic alloy raw powder are simultaneously put into a ball milling tank for ball milling treatment. The remaining operation steps and process parameters are the same as those in Embodiment 1.

[0109] Comparative Example 1

[0110] This comparative example provides a method for preparing a soft magnetic alloy powder core, which is different from that of Embodiment 1 in that: in step S1, no magnesium vapor is introduced, but magnesium oxide is added to the ball milling tank in step S2, and magnesium oxide, acetic acid, absolute ethanol and the soft magnetic alloy raw powder are directly subjected to ball milling treatment. The remaining operation steps and process parameters are the same as those in Embodiment 1.

[0111] Comparative Example 2

[0112] This comparative example provides a method for preparing a soft magnetic alloy magnetic powder core, which is different from Example 1 in that: in step S2, acetic acid is not added, and the remaining operation steps and process parameters are the same as those in Example 1.

[0113] Under the test conditions of 100 kHz and 1 V, the permeability of the magnetic powder cores prepared in Examples 1 to 11 and Comparative Examples 1 to 2 was tested, and the results are shown in Table 1.

[0114] Under the test conditions of loss condition 1 (50 KHz, 100 mT), loss condition 2 (1 MHz, 50 mT), and 25 °C, the losses of the magnetic powder cores prepared in Examples 1 to 11 and Comparative Examples 1 to 2 were tested respectively, and the results are shown in Table 1.

[0115] Table 1

[0116] Number Permeability (H / m) <![CDATA[Loss 1 (Kw / m 3 )]]> <![CDATA[Loss 2 (Kw / m 3 )]]> Example 1 121 152 2059 Example 2 128 199 3425 Example 3 108 132 1897 Example 4 126 189 3299 Example 5 110 141 1987 Example 6 115 178 2843 Example 7 110 156 2139 Example 8 106 218 3492 Example 9 114 159 2187 Example 10 112 169 2539 Example 11 114 161 2210 Comparative Example 1 107 154 2126 Comparative Example 2 103 225 3636

[0117] It can be easily seen from Table 1 that the magnetic powder cores prepared in Examples 1 to 11 of the present invention all have relatively high permeability and low losses. Comparing Example 1 and Example 6, it can be seen that since the amount of magnesium vapor introduced in Example 6 is too low, impurities cannot be effectively removed, the cleanliness of the magnetic powder is reduced, and the coating layer cannot be effectively formed, resulting in a decrease in the permeability of the magnetic powder core. From Example 1 and Example 7, it can be seen that since the amount of magnesium vapor introduced in Example 7 is too high, there is an excess of magnesium vapor and not all of it reacts. After annealing treatment, the uniformity of the coating layer on the surface of the iron-nickel magnetic powder is reduced, which in turn affects the magnetic properties of the product.

[0118] Compared with Example 1, when the amount of acetic acid added in Example 8 is excessive, there is a problem of waste, and the remaining acetic acid after the reaction is likely to produce by-products, resulting in a decrease in the cleanliness of the magnetic powder core; while when the amount of acetic acid added in Example 9 is too low, the reaction is incomplete and the magnesium oxide coating layer cannot be effectively formed, resulting in a decrease in the magnetic properties of the magnetic powder core.

[0119] From Example 1 and Example 10, it can be seen that using ball milling treatment in Example 1 is beneficial to improving the mixing uniformity of acetic acid and the soft magnetic alloy raw powder, so as to form a magnesium oxide coating layer with uniform thickness, thereby improving the permeability of the magnetic powder core.

[0120] Compared with adding acetic acid, absolute ethanol and the soft magnetic alloy raw powder in sequence in Example 1, directly mixing the soft magnetic alloy raw powder, acetic acid and absolute ethanol together and then ball milling in Example 11 results in a decrease in the permeability of the magnetic powder core and an increase in losses. This is mainly because a certain sequence of chemical reactions is used in Example 1 to achieve uniform coating of inorganic compounds, which is beneficial to reducing the low-frequency and high-frequency losses of the magnetic powder core.

[0121] As can be easily seen from Table 1, the magnetic permeability of the magnetic powder core in Example 1 is higher than that in Comparative Example 1. This is mainly because magnesium vapor is introduced in Example 1. Relying on the strong activity of Mg itself and the strong affinity of Mg with impurity elements such as O and S, it is possible to reduce the non-metallic elements doped in the smelting and powder-making processes, improve the product purity, and thus increase the magnetic permeability of the magnetic powder core.

[0122] As can be seen from Table 1, compared with Example 1, the magnetic permeability of Comparative Example 2 has decreased, and at the same time, the loss has increased. In Example 1, by adding acetic acid, a magnesium acetate coating layer is formed through a series of chemical reactions, which can uniformly coat the outer surface of the iron-nickel magnetic powder, helping to reduce the loss of the magnetic powder core. The preparation method provided by the present invention, through the specific design of magnesium, improves the cleanliness of the iron-nickel alloy powder without adding too many impurities, and then enhances the magnetic permeability of the magnetic powder core. At the same time, by using chemical reactions in a specific order, the uniform coating of inorganic compounds is achieved, improving the resistivity of the material and effectively reducing the low-frequency and high-frequency losses of the magnetic powder core.

[0123] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A preparation method of a soft magnetic alloy magnetic powder core, characterized in that The described preparation method includes: Melting a nickel ingot and an iron ingot, introducing magnesium vapor, and making soft magnetic alloy raw powder by gas atomization; mixing acetic acid, an additive with the soft magnetic alloy raw powder to form a coating layer on the outer surface of the soft magnetic alloy raw powder to obtain iron-nickel magnetic powder, and then performing pressing treatment on the iron-nickel magnetic powder to obtain a magnetic powder core.

2. The preparation method according to claim 1, wherein Denote the total mass of the nickel ingot and the iron ingot as 100%, the content of the nickel ingot is 46 - 54 wt%, and the rest is the iron ingot; Preferably, the introduction amount of the magnesium vapor is 0.1 - 0.5 wt%; Preferably, the average particle size of the soft magnetic alloy raw powder is 10 - 30 μm.

3. The preparation method according to claim 1 or 2, characterized in that, Denote the mass of the soft magnetic alloy raw powder as 100%, the addition amount of the acetic acid is 1 - 3 wt%; Preferably, the additive is anhydrous ethanol.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The mixing includes: mixing acetic acid and the additive and stirring evenly, then adding the soft magnetic alloy raw powder for ball milling treatment, and then drying to obtain the iron-nickel magnetic powder; Preferably, the time of the ball milling treatment is 1 - 3 h.

5. The preparation method according to any one of claims 1-4, characterized in that, The described preparation method further includes: annealing the iron-nickel magnetic powder under an inert atmosphere; Preferably, the temperature of the annealing treatment is 600 - 800 °C; Preferably, the time of the annealing treatment is 3 - 5 h.

6. The preparation method according to claim 5, characterized in that, The described preparation method further includes: after ending the annealing treatment, drying the iron-nickel magnetic powder; The manner of the drying treatment includes: mixing a silane coupling agent, a resin binder and a solvent evenly, adding the iron-nickel magnetic powder after the annealing treatment, and performing primary stirring and secondary stirring in sequence to make the solvent volatilize; Preferably, the temperature of the primary stirring is 20 - 30 °C; Preferably, the time of the primary stirring is 10 - 20 min; Preferably, during the secondary stirring, the temperature of the iron-nickel magnetic powder is raised to 100 - 120 °C to make the solvent volatilize; Preferably, the described preparation method further includes: before the drying treatment, cooling and screening the iron-nickel magnetic powder after the annealing treatment in sequence.

7. The preparation method according to claim 6, wherein Denote the mass of the iron-nickel magnetic powder after the annealing treatment as 100%, the addition amount of the silane coupling agent is 0.1 - 1 wt%, and the addition amount of the resin binder is 1 - 3 wt%; Preferably, the silane coupling agent includes any one or a combination of at least two of an amino silane coupling agent, an epoxy silane coupling agent and a vinyl silane coupling agent; Preferably, the resin binder includes any one or a combination of at least two of an epoxy resin binder, a silicone resin binder and a phenolic resin binder; Preferably, the solvent includes ethanol and acetone; Preferably, denote the mass of the iron-nickel magnetic powder after the annealing treatment as 100%, the addition amount of the ethanol is 5 - 7 wt%, and the addition amount of the acetone is 12 - 18 wt%.

8. The preparation method according to any one of claims 1 to 7, characterized in that, The described pressing treatment includes: mixing the iron-nickel magnetic powder and a demolding powder evenly and then molding by pressing, and then performing heat treatment to obtain the magnetic powder core; Preferably, denote the mass of the iron-nickel magnetic powder after the drying treatment as 100%, the addition amount of the demolding powder is 0.1 - 0.3 wt%; Preferably, the mold release powder includes any one or a combination of at least two of zinc stearate powder, magnesium stearate powder, aluminum stearate powder, calcium stearate powder, and graphite powder; Preferably, the pressure for press molding is 1000 - 2000 MPa; Preferably, the heat treatment is carried out in a protective atmosphere or a reducing atmosphere; Preferably, the temperature of the heat treatment is 600 - 800 °C; Preferably, the time of the heat treatment is 30 - 90 min.

9. The preparation method according to any one of claims 1-8, characterized in that, The preparation method specifically includes the following steps: S1 Melting a nickel ingot and an iron ingot, introducing magnesium vapor, and making soft magnetic alloy raw powder by gas atomization; S2 Mixing acetic acid and an additive and stirring evenly, adding the soft magnetic alloy raw powder obtained in step S1 for ball milling and drying to form a coating layer on the outer surface of the soft magnetic alloy raw powder to obtain iron-nickel magnetic powder, and then carrying out annealing treatment on the iron-nickel magnetic powder in an inert atmosphere; S3 Mixing a silane coupling agent, a resin binder, and a solvent evenly, adding the iron-nickel magnetic powder after annealing treatment, and carrying out primary stirring and secondary stirring in sequence to volatilize the solvent to obtain dry iron-nickel magnetic powder; S4 Mixing the dry iron-nickel magnetic powder obtained in step S3 with the mold release powder evenly, press molding, and then carrying out heat treatment to obtain the magnetic powder core.

10. A magnetic powder core, characterized in that, The magnetic powder core is prepared by the preparation method described in any one of claims 1 - 9.