CN113380483B

CN113380483B - Composite soft magnetic material and preparation method thereof

Info

Publication number: CN113380483B
Application number: CN202110648082.0A
Authority: CN
Inventors: 张云逸; 李玉平; 孙永阳; 蒋云涛
Original assignee: Hengdian Group DMEGC Magnetics Co Ltd
Current assignee: Hengdian Group DMEGC Magnetics Co Ltd
Priority date: 2021-06-10
Filing date: 2021-06-10
Publication date: 2023-09-01
Anticipated expiration: 2041-06-10
Also published as: CN113380483A

Abstract

The invention provides a composite soft magnetic material and a preparation method thereof. The composite soft magnetic material comprises an inner core, a first shell layer positioned outside the inner core and a second shell layer positioned outside the first shell layer; the inner core is an alloy, and the alloy comprises iron and silicon; the first shell layer comprises a material obtained by taking inorganic silicon-containing materials as raw materials, and the second shell layer comprises a material obtained by taking organic silicon as raw materials. The method comprises the following steps: 1) Annealing the raw material powder containing iron and silicon, and screening the granularity of an annealed product; 2) Coating the screening powder material with inorganic silicon-containing material for one time; 3) Carrying out secondary coating by using an organosilicon primary coating product; 4) Mixing the secondary coating product with a release agent, and performing secondary pressing; 5) And annealing the pressed product to obtain the composite soft magnetic material. The composite soft magnetic material has low molding pressure, high density and lower loss under the MHz-level high-frequency condition, and can be better suitable for the rapid development of miniaturization and high-frequency of electronic devices.

Description

Composite soft magnetic material and preparation method thereof

Technical Field

The invention belongs to the technical field of magnetic materials, and relates to a composite soft magnetic material and a preparation method thereof.

Background

In recent years, with the rapid development of miniaturization and high frequency of electronic devices, higher demands are being made on soft magnetic materials having both high magnetic permeability and low high frequency loss, and conventional metallic soft magnetic materials and ferrites have failed to meet the use requirements. The soft magnetic composite material SMCs (Soft Magnetic Composite), also called as magnetic powder core, is a kind of soft magnetic material prepared by pressing the soft magnetic powder body into a required shape by adopting a powder metallurgy process after insulating and coating, and through a heat treatment process and the like, has the advantages of low eddy current loss, good frequency characteristic, easy machining and the like, and therefore, the soft magnetic composite material is widely paid attention to all over the world. The soft magnetic composite material combines the advantages of metal and ferrite soft magnetic material, the resistivity of the soft magnetic composite material is greatly improved compared with that of soft magnetic metal, the eddy current loss can be effectively reduced, and the soft magnetic composite material has higher saturation magnetization intensity than that of soft magnetic ferrite, and can meet the requirements of miniaturization and integration of power electronic devices. The soft magnetic composite material can be pressed into various complex shapes such as ring shape, E shape, u shape and the like, and the integrated production of components and parts is realized. Therefore, the soft magnetic composite material has become a magnetic material with the fastest development and application growth speed, and is used for producing various power electronic key components such as inductors, filters, chokes, transformers and the like. The high-speed development of modern information technology and power electronics industry, while promoting the development of soft magnetic composite materials, also put forward higher requirements on the magnetic performance and power loss of the soft magnetic composite materials. The international research on the soft magnetic composite material is mainly developed around two main lines, namely, a soft magnetic alloy system with specific performance is developed to meet the requirements of different application occasions, and an insulating coating process is innovated, so that the high-frequency loss is reduced.

The soft magnetic composite material is mainly used in the fields of PFC inductance, buck-boost inductance, output filter inductance, power inductance, energy storage inductance and the like, and is gradually replaced by other soft magnetic materials to be widely applied to inductance devices due to excellent anti-saturation capacity and good high-temperature characteristics, so that a good foundation is laid for miniaturization and reliability of power electronics. Along with the trend of high frequency of power semiconductors, power electronic devices are developed towards high frequency, high power density, miniaturization and energy saving, and metal soft magnetic elements are used for overcoming various performance defects of silicon steel, ferrite, amorphous strips and the like, and meanwhile, the advantages of the metal magnetic powder core in terms of high magnetic flux density, small volume, low noise, strong anti-saturation capability, good frequency and temperature stability and capability of processing different devices are revealed, so that the application scene is increasingly abundant. Meanwhile, the fields are closely related to the strategic planning and energy conservation and emission reduction of our country, and along with the great increase of the investment of the national re-technology field in the years, the industries are expected to develop more rapidly in the future, and have wide development prospects.

However, the soft magnetic composite material with better market at present has higher loss under the ultra-high frequency of MHz level (the loss exceeds 33000Kw/m under the condition of 2MHz 200 mT) ³ ) There is thus much room for improvement. Meanwhile, the current market has great demands for MHz high-frequency and low-loss metal soft magnetic composite materials.

CN107671298A discloses a high-frequency fesai alloy powder and a preparation method thereof, belonging to the technical field of powder preparation. The preparation method takes rod-shaped polished iron, massive metallic silicon and pure aluminum ingot as raw materials, the raw materials are proportioned and weighed according to proportion, alloy molten steel with required components is obtained by vacuum smelting, then alloy raw powder is obtained by inert gas atomization, and the raw powder is collected and screened to obtain fine powder.

CN110957096a discloses a ferro-silicon-aluminum magnetic core, the preparation method comprises: smelting an ingot, and adding modified superfine SiC powder in the smelting process; preparing Fe-Si-Al powder; phosphating the surface of the prepared Fe-Si-Al powder: insulating and coating the phosphated Fe-Si-Al powder, and pressing the treated material into Fe-Si-Al magnetic core; annealing the pressed iron-silicon-aluminum magnetic core in a nitrogen atmosphere; and carrying out surface spraying treatment on the annealed iron-silicon-aluminum magnetic core.

However, the process for preparing the magnetic powder core by the method is complex, the forming pressure is high, and the loss is high under the high-frequency condition of MHz level.

Disclosure of Invention

Aiming at the defects existing in the prior art, the invention aims to provide a composite soft magnetic material and a preparation method thereof. The composite soft magnetic material provided by the invention has low molding pressure, high density and lower loss under the MHz-level high-frequency condition.

To achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a composite soft magnetic material comprising a core, a first shell layer located outside the core, and a second shell layer located outside the first shell layer; the inner core is an alloy, and the alloy comprises iron and silicon; the first shell layer comprises a material obtained by taking inorganic silicon-containing materials as raw materials, and the second shell layer comprises a material obtained by taking organic silicon as raw materials.

In the composite soft magnetic material provided by the invention, the first shell layer positioned in the middle is used for primary insulating coating, and the second shell layer positioned at the outermost side is used for further reinforcing coating and enhancing wear resistance.

The composite soft magnetic material provided by the invention is a soft magnetic material with low molding pressure, high density and low loss under the MHz-level high-frequency condition, and can be better suitable for the miniaturization and the rapid development of high-frequency electronic devices.

In the present invention, the content of Fe in the inner core is preferably 91 to 93%, the content of Si is 5 to 5.5%, the content of other metals is 2 to 3.5%, and further preferably 91.8%, the content of Si is 5.2%, and the content of other metals is 3.0%.

The following preferred technical solutions are used as the present invention, but not as limitations on the technical solutions provided by the present invention, and the technical objects and advantageous effects of the present invention can be better achieved and achieved by the following preferred technical solutions.

As a preferable technical scheme of the invention, the alloy is Fe-Si-Al alloy;

preferably, the inorganic siliceous material comprises any of sodium silicate, potassium silicate or magnesium silicate or a combination of at least two thereof.

Preferably, the silicone comprises a liquid silicone.

Preferably, the particle size of the inner core is 15-53 μm, for example 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm or 53 μm, etc., preferably 15-21 μm. In the invention, the particle size of the inner core has influence on the product in the forming of the magnetic ring and the level of loss.

Preferably, the thickness of the first shell layer is 50-100nm, for example 50nm, 60nm, 70nm, 80nm, 90nm or 100nm, etc. In the invention, if the first shell layer is too thick, the coating cannot be compact; if the first shell layer is too thin, it may cause cracking when coating the second shell layer.

Preferably, the thickness of the second shell layer is 90-220nm, for example 90nm, 100nm, 150nm, 200nm or 220nm, etc. In the present invention, if the second shell layer is too thick, it may cause a decrease in density after press molding; if the second shell layer is too thin, it may be easily cracked to deteriorate the performance.

Preferably, phosphorus elements are also distributed on the surface and/or the inside of the inner core of the composite soft magnetic material. In the present invention, phosphorus element may be incorporated into the composite soft magnetic material due to insulation using phosphoric acid.

The composite soft magnetic material provided by the invention can also be provided with a small amount of other doping elements due to the use of a release agent.

In a second aspect, the present invention provides a method for preparing a composite soft magnetic material according to the first aspect, the method comprising the steps of:

(1) Annealing the iron-containing silicon raw material powder in a protective atmosphere, and screening the granularity of an annealed product to obtain screening powder;

(2) Coating the screening powder in the step (1) for the first time by using an inorganic silicon-containing material to obtain a first-time coated product;

(3) Carrying out secondary coating on the primary coating product in the step (2) by using organic silicon to obtain a secondary coating product;

(4) Mixing the secondary coating product obtained in the step (3) with a release agent, and pressing to obtain a pressed product;

(5) And (3) annealing the pressed product in the step (4) in a protective atmosphere to obtain the composite soft magnetic material.

In the preparation method provided by the invention, the annealing effect of the step (1) is to reduce the hardness and improve the cutting processability; the annealing in step (5) consists in stress relief.

In the preparation method provided by the invention, the release agent has the function of helping to release the mold better after the pressing is completed.

As a preferable technical scheme of the invention, the iron-silicon-containing raw material powder in the step (1) comprises iron-silicon-aluminum powder.

Preferably, the protective atmosphere of step (1) comprises nitrogen and/or argon.

Preferably, the annealing temperature in step (1) is 500-1000 ℃, e.g. 500 ℃, 600 ℃, 700 ℃, 800 ℃, 900 ℃, 1000 ℃, etc.

Preferably, the annealing in step (1) is performed for a period of time ranging from 3 to 20 hours, such as 3 hours, 5 hours, 10 hours, 15 hours, or 20 hours, etc.

Preferably, the method of particle size screening of step (1) comprises screening.

Preferably, the particle size of the screening powder in step (1) is 15 to 53. Mu.m, for example 15 μm, 20 μm, 30 μm, 40 μm, 50 μm or 53. Mu.m, etc., preferably 15 to 21. Mu.m. In the invention, if the particle size of the screening powder is too large, the loss of the pressed magnetic ring is too high; if the particle size of the sifting powder is too small, it may cause difficulty in press molding.

As a preferred technical solution of the present invention, step (2) further includes: and before one-time coating, insulating treatment is carried out on the screening powder.

Preferably, the insulation treatment method comprises: and mixing the acid solution with the screening powder, heating and stirring until the powder is completely dried, and sieving to obtain the insulating powder.

Preferably, the acid comprises phosphoric acid.

Preferably, the acid is present in a mass fraction of 0.1-6%, e.g. 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5% or 6% based on 100% of the mass of the screening powder.

Preferably, in the acid solution, the solvent is an organic solvent.

Preferably, the organic solvent comprises any one or a combination of at least two of n-butanol, tert-butanol, methanol or acetone.

In the preferred embodiment of the present invention, in the step (2), the mass fraction of the inorganic silicon-containing material is 0.5 to 3%, for example, 0.5%, 1%, 2% or 3%, based on 100% of the mass of the screening powder.

Preferably, the method of primary coating in step (2) includes: mixing inorganic silicon-containing material with the screening powder in inorganic solvent, heating and stirring until the mixture is completely dried, and sieving.

Preferably, the inorganic solvent comprises water.

In the preferred embodiment of the present invention, in the step (3), the mass fraction of the organosilicon is 0.5 to 3%, for example, 0.5%, 1%, 2% or 3%, based on 100% of the mass of the screening powder.

Preferably, the secondary coating method in step (3) includes: mixing the organic silicon and the primary coating product in an organic solvent, heating and stirring until the mixture is completely dried, and granulating.

In a preferred embodiment of the present invention, the release agent in step (4) is a stearic acid-based release agent.

Preferably, the stearic acid-based release agent comprises any one or a combination of at least two of zinc stearate, aluminum stearate, magnesium stearate, calcium stearate or lithium stearate, preferably zinc stearate.

Preferably, in step (4), the release agent is 0.1 to 2% by mass, for example 0.1%, 0.5%, 1%, 1.5% or 2% by mass, based on 100% by mass of the screening powder. In the present invention, if the amount of the release agent is too large, performance may be deteriorated; if the amount of the release agent is too small, it may cause difficulty in releasing the mold and even peeling may occur.

Preferably, the method of mixing of step (4) comprises: after heating the release agent to 100-300 ℃, for example, 100 ℃, 150 ℃, 200 ℃, 250 ℃, 300 ℃ or the like, is mixed with the secondary coating product. In the present invention, the purpose of heating the release agent to 100-300 ℃ is to keep the release agent in a molten state, and to mix it with the magnetic powder well.

Preferably, in the step (4), the pressing is a secondary pressing, and the pressure of the first pressing is lower than that of the second pressing.

In the preparation method provided by the invention, the effect of twice pressing is to obtain the magnetic ring with high density under lower highest pressure.

Preferably, in step (4), the pressure of the first pressing is 200 to 500MPa, for example 200MPa, 300MPa, 400MPa or 500MPa, etc.

Preferably, in step (4), the pressure of the second pressing is 800-1200MPa, for example 800MPa, 900MPa, 1000MPa, 1100MPa or 1200MPa, etc.

As a preferred embodiment of the present invention, the protective atmosphere in step (5) includes nitrogen and/or argon.

Preferably, the temperature of the annealing in step (5) is 500-900 ℃, e.g. 500 ℃, 600 ℃, 700 ℃, 800 ℃, 900 ℃ or the like.

Preferably, the annealing in step (5) is performed for a period of time ranging from 3 to 20 hours, such as 3 hours, 5 hours, 10 hours, 15 hours, or 20 hours, etc.

As a further preferred technical solution of the preparation method according to the invention, the method comprises the following steps: the method comprises the following steps:

(1) Annealing the iron-containing silicon raw material powder for 3-20 hours at 500-1000 ℃ in a protective atmosphere, and sieving the annealed product to obtain screening powder with the particle size of 15-21 mu m; the iron-containing silicon raw material powder comprises iron-silicon-aluminum powder;

(2) Mixing the phosphoric acid solution with the screening powder in the step (1), heating and stirring until the mixture is completely dried, and sieving to obtain insulating powder; mixing an inorganic silicon-containing material with the insulating powder in an inorganic solvent, heating and stirring until the mixture is completely dried, and sieving to obtain a primary coating product; the mass fraction of the phosphoric acid is 0.1-6% based on 100% of the mass of the screening powder; the mass fraction of the inorganic silicon-containing material is 0.5-3%;

(3) Mixing the organic silicon and the primary coating product in the step (2) in an organic solvent, heating and stirring until the primary coating product is completely dried, and granulating to obtain a secondary coating product; the mass fraction of the organic silicon is 0.5-3% based on 100% of the mass of the screening powder;

(4) Heating the release agent to 100-300 ℃, and mixing with the secondary coating product in the step (3); pressing to obtain a pressed product; the pressing is secondary pressing, the pressure intensity of the first pressing is 200-500MPa, and the pressure intensity of the second pressing is 800-1200MPa; the mass fraction of the release agent is 0.1-2% based on 100% of the mass of the screening powder;

(5) And (3) annealing the pressed product in the step (4) for 3-20 hours at 500-900 ℃ in a protective atmosphere to obtain the composite soft magnetic material.

Compared with the prior art, the invention has the following beneficial effects:

(1) The composite soft magnetic material provided by the invention is a soft magnetic material with low molding pressure, high density and low loss under the MHz-level high-frequency condition, and can be better suitable for the miniaturization and the rapid development of high-frequency electronic devices.

(2) The preparation method provided by the invention comprehensively utilizes the processes of twice coating, release agent and twice pressing, and is beneficial to improving the performance of the product.

Detailed Description

For better illustrating the present invention, the technical scheme of the present invention is convenient to understand, and the present invention is further described in detail below. The following examples are merely illustrative of the present invention and are not intended to represent or limit the scope of the invention as defined in the claims.

The following are exemplary but non-limiting examples of the invention:

example 1

The composite soft magnetic material is prepared according to the following method:

(1) Iron-silicon-aluminum powder with the Fe content of 91.8%, the Si content of 5.2% and the Al content of 3.0% is selected as raw material powder.

(2) And (3) annealing the raw material powder in a tube furnace for 15 hours at the temperature of 900 ℃ under the protection of nitrogen atmosphere.

(3) Sieving the annealed raw material powder with a 800-mesh screen to obtain Fe-Si-Al powder (sieving powder) with powder particle size of 15-21 μm.

(4) The Fe-Si-Al powder is insulated, 1% phosphoric acid (based on 100% of the mass of the screened powder) is added into the n-butanol as a solvent, and the mixture is fully mixed, heated and stirred until the mixture is completely dried and screened.

(5) Coating the insulated Fe-Si-Al powder, adding 1.5% sodium silicate (based on 100% of the mass of the screened powder) into the insulated Fe-Si-Al powder by using water as a solvent, fully mixing, heating and stirring until the powder is completely dried, and sieving the powder.

(6) And (3) coating the coated Fe-Si-Al powder again, adding 1.5% of liquid silicone resin (based on 100% of the mass of the screened powder) into the coated Fe-Si-Al powder by taking n-butanol as a solvent, fully mixing, heating, stirring to be drier, and granulating.

(7) 1% of zinc stearate (based on 100% of the mass of the powder) is heated to a molten state at 220 ℃ and fully mixed with the granulated sendust in a stirrer.

(8) And pressing the prepared Fe-Si-Al powder into a magnetic powder core at a low pressure of 300 MPa.

(9) And (3) carrying out secondary pressing on the magnetic powder core pressed and formed under low pressure at the pressure of 1000MPa to obtain the magnetic powder core with OD=8.05 mm, ID=4.95 mm and Ht=1.8 mm.

(10) And (3) annealing the magnetic powder core obtained by secondary pressing in a tube furnace for 5 hours at the temperature of 800 ℃ under the protection of nitrogen atmosphere to obtain the composite soft magnetic material, and then testing the magnetic property.

The composite soft magnetic material core prepared by the embodiment, a first shell layer positioned outside the core, and a second shell layer positioned outside the first shell layer; the inner core is made of Fe-Si-Al alloy, the first shell layer is made of sodium silicate, and the second shell layer is made of silicone resin. The particle size of the inner core is 15-21 μm, the thickness of the first shell layer is 70-80nm, and the thickness of the second shell layer is 100-120nm.

Example 2

Other operations of this embodiment are the same as those of embodiment 1, except that: the particle size of the powder is 19-26 mu m. The particle size of the powder is the particle size of the inner core of the obtained composite soft magnetic material product.

Example 3

Other operations of this embodiment are the same as those of embodiment 1, except that: the particle size of the powder is 21-30 mu m. The particle size of the powder is the particle size of the inner core of the obtained composite soft magnetic material product.

Example 4

Other operations of this embodiment are the same as those of embodiment 1, except that: the particle size of the powder is 26-38 mu m. The particle size of the powder is the particle size of the inner core of the obtained composite soft magnetic material product.

Example 5

Other operations of this embodiment are the same as those of embodiment 1, except that: the particle size of the powder is 30-45 μm. The particle size of the powder is the particle size of the inner core of the obtained composite soft magnetic material product.

Example 6

Other operations of this embodiment are the same as those of embodiment 1, except that: the particle size of the powder is 38-53 mu m. The particle size of the powder is the particle size of the inner core of the obtained composite soft magnetic material product.

Example 7

(8) And pressing the prepared sendust powder under the pressure of 1000MPa to obtain the magnetic powder core with OD=8.05 mm, ID=4.95 mm and Ht=1.8 mm.

(9) And (3) annealing the magnetic powder core obtained by secondary pressing in a tube furnace for 5 hours at the temperature of 800 ℃ under the protection of nitrogen atmosphere to obtain the composite soft magnetic material, and then testing the magnetic property.

Example 8

Other operations of this embodiment are the same as those of embodiment 1, except that: at normal temperature, 1% of zinc stearate is sieved by a 400-mesh sieve, and the sieved zinc stearate is fully mixed with the granulated powder by a spoon.

Example 9

Other operations of this embodiment are the same as those of embodiment 1, except that: at normal temperature, 1% of zinc stearate is sieved by a 400-mesh sieve, and the sieved zinc stearate and the granulated powder are simultaneously filled into a ball milling tank and mixed in a ball mill for 15min.

Example 10

Other operations of this embodiment are the same as those of embodiment 1, except that: heating 1% zinc stearate to molten state at 100deg.C, and mixing with granulated sendust powder in stirrer.

Example 11

Other operations of this embodiment are the same as those of embodiment 1, except that: heating 1% zinc stearate to molten state at 300 ℃, and fully mixing with granulated Fe-Si-Al powder in a stirrer.

Example 12

Other operations of this embodiment are the same as those of embodiment 1, except that: 1% of magnesium stearate is heated to a molten state at 220 ℃, and fully mixed with the granulated Fe-Si-Al powder in a stirrer.

Example 13

Other operations of this embodiment are the same as those of embodiment 1, except that: heating 1% of calcium stearate to a molten state at 220 ℃, and fully mixing with the granulated Fe-Si-Al powder in a stirrer.

Example 14

Other operations of this embodiment are the same as those of embodiment 1, except that: 1% of lithium stearate is heated to a molten state at 220 ℃, and fully mixed with the granulated Fe-Si-Al powder in a stirrer.

Example 15

Other operations of this embodiment are the same as those of embodiment 1, except that: heating 1% of aluminum stearate to a molten state at 220 ℃, and fully mixing with the granulated Fe-Si-Al powder in a stirrer.

Example 16

(2) And (3) annealing the raw material powder in a tube furnace for 20 hours at the temperature of 500 ℃ under the protection of nitrogen atmosphere.

(4) The Fe-Si-Al powder is insulated, 0.1% phosphoric acid (based on 100% of the mass of the screened powder) is added into the n-butanol as a solvent, and the mixture is fully mixed, heated and stirred until the mixture is completely dried and screened.

(5) Coating the insulated Fe-Si-Al powder, adding 0.5% sodium silicate (based on 100% of the mass of the screened powder) into the insulated Fe-Si-Al powder by using water as a solvent, fully mixing, heating and stirring until the powder is completely dried, and sieving the powder.

(6) And (3) coating the coated Fe-Si-Al powder again, adding 3% of liquid silicone resin (based on 100% of the mass of the screened powder) into the n-butanol serving as a solvent, fully mixing, heating, stirring to be drier, and granulating.

(8) And pressing the prepared Fe-Si-Al powder into a magnetic powder core at a low pressure of 200 MPa.

(9) And (3) carrying out secondary pressing on the magnetic powder core pressed and formed under low pressure at the pressure of 800MPa to obtain the magnetic powder core with OD=8.05 mm, ID=4.95 mm and Ht=1.8 mm.

(10) And (3) annealing the magnetic powder core obtained by secondary pressing in a tube furnace for 20 hours at the temperature of 500 ℃ under the protection of nitrogen atmosphere to obtain the composite soft magnetic material, and then testing the magnetic property.

Example 17

(2) And (3) annealing the raw material powder in a tube furnace for 3 hours at the temperature of 1000 ℃ under the protection of nitrogen atmosphere.

(4) The Fe-Si-Al powder is insulated, 6% phosphoric acid (based on 100% of the mass of the screened powder) is added by taking n-butanol as a solvent, and the mixture is fully mixed, heated and stirred until the mixture is completely dried and screened.

(5) Coating the insulated Fe-Si-Al powder, adding 3% sodium silicate (based on 100% of the mass of the screened powder) into the insulated Fe-Si-Al powder by using water as a solvent, fully mixing, heating and stirring until the powder is completely dried, and sieving the powder.

(6) And (3) coating the coated Fe-Si-Al powder again, adding 0.5% of liquid silicone resin (based on 100% of the mass of the screened powder) into the coated Fe-Si-Al powder by taking n-butanol as a solvent, fully mixing, heating, stirring to be drier, and granulating.

(8) And pressing the prepared Fe-Si-Al powder into a magnetic powder core at a low pressure of 500 MPa.

(9) And (3) carrying out secondary pressing on the magnetic powder core pressed and formed under low pressure at the pressure of 1200MPa to obtain the magnetic powder core with OD=8.05 mm, ID=4.95 mm and Ht=1.8 mm.

(10) And (3) annealing the magnetic powder core obtained by secondary pressing in a tube furnace for 3 hours at the temperature of 900 ℃ under the protection of nitrogen atmosphere to obtain the composite soft magnetic material, and then testing the magnetic property.

Comparative example 1

The other operations of this comparative example are the same as in example 1, except that: the comparative example was carried out without the operation of step (7), i.e., without the addition of a mold release agent.

Test method

The products provided in the examples and comparative examples were tested for side conduction and loss at 2MHz, 200mT, and the results are shown in the following table:

TABLE 1

As can be seen from the above examples and comparative examples, the composite soft magnetic material obtained by the method provided by the examples has low molding pressure, high density and low loss under the MHz high-frequency condition.

From a comparison of example 1 and examples 2-6, it can be seen that sendust cores with different powder particle sizes affect the product loss.

As can be seen from a comparison of examples 1 and 7, the loss is higher with only one press than with two presses.

It can be seen from examples 1 and 8-15 that the appropriate annealing temperature can effectively reduce the loss of the magnetic ring.

Comparative example 1 does not use a release agent, which results in difficulty in releasing the mold, and a large amount of the magnetic powder core is broken and peeled.

The applicant states that the detailed method of the present invention is illustrated by the above examples, but the present invention is not limited to the detailed method described above, i.e. it does not mean that the present invention must be practiced in dependence upon the detailed method described above. It should be apparent to those skilled in the art that any modification of the present invention, equivalent substitution of raw materials for the product of the present invention, addition of auxiliary components, selection of specific modes, etc., falls within the scope of the present invention and the scope of disclosure.

Claims

1. The preparation method of the composite soft magnetic material applied to the MHZ level high frequency condition is characterized in that the composite soft magnetic material comprises an inner core, a first shell layer positioned outside the inner core and a second shell layer positioned outside the first shell layer; the inner core is an alloy, and the alloy is Fe-Si-Al alloy; the first shell layer comprises a material obtained by taking an inorganic silicon-containing material as a raw material, and the second shell layer comprises a material obtained by taking organic silicon as a raw material; the particle size of the inner core is 15-21 mu m; the thickness of the first shell layer is 50-100nm, and the thickness of the second shell layer is 90-220nm;

the preparation method of the composite soft magnetic material comprises the following steps:

(1) Annealing the iron-containing silicon raw material powder in a protective atmosphere, and screening the granularity of an annealed product to obtain screening powder; the particle size distribution range of the screening powder is 15-21 mu m; the particle size screening method comprises screening; the iron-containing silicon raw material powder comprises iron-silicon-aluminum powder;

(4) Mixing the secondary coating product obtained in the step (3) with a release agent, and pressing to obtain a pressed product; the pressing is secondary pressing, and the pressure intensity of the first pressing is lower than that of the second pressing; the pressure of the first pressing is 200-500Mpa, and the pressure of the second pressing is 800-1200Mpa;

the mixing method comprises the following steps: heating the release agent to 100-300 ℃, and mixing with the secondary coating product; the release agent is stearic acid release agent;

2. The method of claim 1, wherein the inorganic siliceous material comprises any one or a combination of at least two of sodium silicate, potassium silicate, or magnesium silicate.

3. The method of claim 1, wherein the silicone comprises a liquid silicone.

4. The preparation method according to claim 1, wherein phosphorus is further distributed on the surface and/or inside of the inner core of the composite soft magnetic material.

5. The method of claim 1, wherein the protective atmosphere of step (1) comprises nitrogen and/or argon.

6. The method of claim 1, wherein the annealing in step (1) is performed at a temperature of 500-1000 ℃.

7. The method of claim 1, wherein the annealing in step (1) is performed for a period of 3 to 20 hours.

8. The method of claim 1, wherein step (2) further comprises: and before one-time coating, insulating treatment is carried out on the screening powder.

9. The method of manufacturing according to claim 8, wherein the method of insulating treatment comprises: and mixing the acid solution with the screening powder, heating and stirring until the powder is completely dried, and sieving to obtain the insulating powder.

10. The method of claim 9, wherein the acid comprises phosphoric acid.

11. The production method according to claim 9, wherein the mass fraction of the acid is 0.1 to 6% based on 100% of the mass of the screening powder.

12. The method according to claim 9, wherein the solvent in the acid solution is an organic solvent.

13. The method of claim 12, wherein the organic solvent comprises any one or a combination of at least two of n-butanol, t-butanol, methanol, or acetone.

14. The method according to claim 1, wherein in the step (2), the mass fraction of the inorganic silicon-containing material is 0.5 to 3% based on 100% of the mass of the screening powder.

15. The method of claim 1, wherein the primary coating in step (2) comprises: mixing inorganic silicon-containing material with the screening powder in inorganic solvent, heating and stirring until the mixture is completely dried, and sieving.

16. The method of claim 15, wherein the inorganic solvent comprises water.

17. The method according to claim 1, wherein in the step (3), the mass fraction of the silicone is 0.5 to 3% based on 100% of the mass of the screening powder.

18. The method of claim 1, wherein the secondary coating in step (3) comprises: mixing the organic silicon and the primary coating product in an organic solvent, heating and stirring until the mixture is completely dried, and granulating.

19. The method of claim 18, wherein the organic solvent comprises any one or a combination of at least two of n-butanol, t-butanol, methanol, or acetone.

20. The method of claim 1, wherein the stearic acid-based release agent comprises any one or a combination of at least two of zinc stearate, aluminum stearate, magnesium stearate, calcium stearate, or lithium stearate.

21. The method of making according to claim 20, wherein the stearic acid-based release agent comprises zinc stearate.

22. The method according to claim 1, wherein in the step (4), the mass fraction of the release agent is 0.1 to 2% based on 100% of the mass of the powder.

23. The method of claim 1, wherein the protective atmosphere of step (5) comprises nitrogen and/or argon.

24. The method of claim 1, wherein the annealing in step (5) is performed at a temperature of 500-900 ℃.

25. The method of claim 1, wherein the annealing in step (5) is performed for a period of 3 to 20 hours.

26. The method of preparation according to claim 1, characterized in that it comprises the steps of:

(1) Annealing the iron-containing silicon raw material powder for 3-20 hours at 500-1000 ℃ in a protective atmosphere, and sieving the annealed product to obtain screening powder with the particle size distribution range of 15-21 mu m; the iron-containing silicon raw material powder comprises iron-silicon-aluminum powder;

(4) Heating the release agent to 100-300 ℃, and mixing with the secondary coating product in the step (3); pressing to obtain a pressed product; the pressing is secondary pressing, the pressure intensity of the first pressing is 200-500MPa, and the pressure intensity of the second pressing is 800-1200MPa; the mass fraction of the release agent is 0.1-2% based on 100% of the mass of the screening powder; the release agent is stearic acid release agent;