阅读说明：本技术 一种基于还原铁粉合金化生产铁基软磁铁芯制备方法 (Preparation method for producing iron-based soft magnetic iron core based on reduced iron powder alloying ) 是由 黄华钦 赵乾 吴朝阳 黄贞益 孔辉 于宗峰 于 2021-08-31 设计创作，主要内容包括：本发明公开了一种基于还原铁粉合金化生产铁基软磁铁芯制备方法,属于软磁材料及粉末冶金技术领域。该方法包括：(1)高纯还原铁粉氢还原；(2)将高纯还原铁粉与合金粉、粘结剂混匀后合金化得到铁基软磁粉末；(3)进行表面无机绝缘包覆处理；(4)将包覆处理后的铁基软磁粉末加入丙酮树脂溶液中,加热搅拌后与脱模剂混匀进行压制,得到铁基软磁复合块体；(5)对铁基软磁复合块体进行热处理得到铁基软磁铁芯。本发明的方法,工艺简单、成本低,能够有效减少熔炼过程中合金成分的烧损,基本消除卫星粉和表面凹坑等缺陷,避免了在凝固过程中易出现成分偏析的情况。(The invention discloses a preparation method for producing an iron-based soft magnetic iron core based on reduced iron powder alloying, belonging to the technical field of soft magnetic materials and powder metallurgy. The method comprises the following steps: (1) hydrogen reduction of high-purity reduced iron powder; (2) uniformly mixing high-purity reduced iron powder, alloy powder and a binder, and alloying to obtain iron-based soft magnetic powder; (3) carrying out surface inorganic insulation coating treatment; (4) adding the coated iron-based soft magnetic powder into an acetone resin solution, heating and stirring, uniformly mixing with a release agent, and pressing to obtain an iron-based soft magnetic composite block; (5) and carrying out heat treatment on the iron-based soft magnetic composite block to obtain the iron-based soft magnetic iron core. The method has simple process and low cost, can effectively reduce the burning loss of alloy components in the smelting process, basically eliminates the defects of satellite powder, surface pits and the like, and avoids the condition of easy component segregation in the solidification process.)

1. A preparation method for producing an iron-based soft magnetic iron core based on reduced iron powder alloying is characterized by comprising the following steps:

(1) reducing high-purity reduced iron powder: reducing iron scale or concentrate powder to obtain high-purity reduced iron powder;

(2) alloying treatment: uniformly mixing the high-purity reduced iron powder obtained in the step (1), alloy powder and a binder, and then alloying to obtain iron-based soft magnetic powder;

(3) inorganic insulating coating: carrying out surface inorganic insulation coating treatment on the iron-based soft magnetic powder obtained in the step (2) to obtain iron-based soft magnetic powder with surface inorganic insulation coating;

(4) and (3) pressing and forming: adding the iron-based soft magnetic powder obtained in the step (3) into an acetone resin solution, heating and stirring the mixture, uniformly mixing the mixture with a release agent, then putting the mixture into a forming die, and performing compression forming to obtain an iron-based soft magnetic composite block;

(5) and (3) heat treatment: and (4) carrying out heat treatment on the iron-based soft magnetic composite block obtained in the step (4) under the protection of inert gas, and cooling along with the furnace to obtain the iron-based soft magnetic iron core.

2. A method for manufacturing an iron-based soft magnetic core based on reduced iron powder alloying as claimed in claim 1, wherein: in the step (1), the granularity of the iron scale or the concentrate powder is 0.1-0.35mm, the high-purity reduced iron powder obtained by three-stage hydrogen reduction is dendritic or flat, and the loose packed density is 2.7-3.0g/cm³The content of metallic iron is more than or equal to 99.1 percent, the content of hydrochloric acid insoluble substances is less than or equal to 0.20 percent, and the particle size of the obtained reduced iron powder is 20-200 mu m.

3. The manufacturing method of an iron-based soft magnetic core based on reduced iron powder alloying as claimed in claim 1, wherein: in the step (2), the mass ratio of the reduced iron powder to the alloy powder is 1: (0.02-0.1), wherein the mass ratio of the total mass of the reduced iron powder and the alloy powder to the binder is 1: (0.01-0.02); the alloy powder adopts any one or the combination of more than two of silicon, aluminum, molybdenum, boron, chromium, nickel, copper, manganese and the like, and the granularity of the alloy powder is controlled to be 0.5-5 mu m; the adhesive is one of polyethylene or polypropylene.

4. A method for manufacturing an iron-based soft magnetic core based on reduced iron powder alloying according to claim 3, characterized in that: in the step (2), the alloying temperature and the alloying time satisfy the following formula:

wherein m is the mass of the alloy powder and the unit is kg; m is the mass of the high-purity reduced iron powder, and the unit is kg; t is alloying time in units of s; t is the alloying temperature, and the unit is; d is the powder particle size in m; the alloying temperature range is 800-1000 ℃.

5. A method for manufacturing an iron-based soft magnetic core based on reduced iron powder alloying according to any one of claims 1 to 4, characterized in that: in the step (2), the alloying treatment process is carried out in the protective atmosphere of nitrogen or argon; the mixing mode adopts ball milling, the ball milling rotating speed is controlled to be 50-150rpm, and the ball milling time is 5-60 min.

6. A method for manufacturing an iron-based soft magnetic core based on reduced iron powder alloying as recited in claim 5, wherein: in the step (3), performing inorganic insulating coating treatment on the surface of the obtained iron-based soft magnetic powder by adopting any one of methods of fluidized gas phase in-situ deposition, simple ball milling and liquid phase deposition, wherein the coated inorganic insulating layer adopts SiO₂、TiO₂、Al₂O₃Or MgO.

7. A method for manufacturing an iron-based soft magnetic core based on reduced iron powder alloying as recited in claim 5, wherein: in the step (4), the resin in the acetone resin solution is any one of organic silicon resin, epoxy resin or phenolic resin, and the mass ratio of the iron-based soft magnetic powder coated with the inorganic insulation on the surface to the resin is 1: (0.01-0.02) and the mass ratio of the resin to the acetone is 1: 10.

8. A method for manufacturing an iron-based soft magnetic core based on reduced iron powder alloying as recited in claim 7, wherein: in the step (4), the mass ratio of the heated and stirred powder to the release agent is 1: (0.05-0.1), the release agent is any one of zinc stearate or magnesium stearate, the temperature of the compression molding is 20-30 ℃, the compression pressure is 1500-1700MPa, and the compression time is 5-30 s.

9. A method for manufacturing an iron-based soft magnetic core based on reduced iron powder alloying as recited in claim 7, wherein: in the step (5), nitrogen or argon is used as inert gas; the heat treatment comprises stress relief annealing and diffusion annealing, wherein the annealing temperature is controlled to be 900-1100 ℃, and the annealing time is controlled to be 0.5-3 h.

Technical Field

The invention relates to the technical field of soft magnetic materials and powder metallurgy, in particular to a preparation method for producing an iron-based soft magnetic iron core based on reduced iron powder alloying.

Background

The soft magnetic iron core made of the iron-based soft magnetic powder has high saturation induction strength and permeability, and is an important component of motors, transformers, sensors and other electronic instruments in industry. Research shows that the shape and performance of the iron-based soft magnetic powder directly determine the quality of the soft magnetic iron core and subsequent products.

At present, the soft magnetic iron core mainly takes atomized iron-based powder as a raw material. Generally, various alloy powders are mixed and melted in proportion, liquid is crushed and atomized into small liquid drops by means of high-speed rotating fluid, airflow, acoustic vibration and the like, the small liquid drops are rapidly solidified into the alloy powders in the environments of air, inert gas, high-pressure water mist and the like, but the atomized iron-based powders are easy to cause burning loss of alloy components in the melting process, are heated unevenly when being rapidly sprayed, often have defects of satellite powder, surface pits and the like, and are easy to generate component segregation in the solidification process.

For example, chinese patent application No. CN201610384098.4 (2016, 06, 02) discloses a method for preparing an iron-silicon-chromium soft magnetic powder, which discloses the following steps: the Fe-Si-Cr alloy powder is proportionally mixed and added into a medium-frequency induction furnace, an alloy liquid is obtained through atmospheric smelting, two atomizing media, namely ultrahigh-pressure atomizing water and low-pressure vortex gas, simultaneously act on the alloy liquid, the alloy liquid is powerfully crushed into a large number of fine metal molten drops, and then the alloy liquid is cooled and solidified into Fe-Si-Cr soft magnetic alloy powder.

In addition, most of the atomized iron-based powder is spherical or spheroidal, more pores exist in the subsequent pressing link of the iron-based soft magnetic iron core, and the magnetic permeability of the product is reduced. For example, the application with the chinese patent application number of cn201810315457.x (application date of 2018, 04, 10) discloses an iron-silicon-titanium magnetic powder core, a preparation method and an application thereof, wherein the application adopts gas atomized powder, and discloses the following steps: firstly, the mass ratio is (92.2-92.8): 6.5: (0.66-1.0) mixing an iron source, a silicon source and a titanium source, preparing iron-silicon-titanium alloy powder by using a gas atomization method, mixing the obtained iron-silicon-titanium alloy powder with a proper amount of organic silicon resin solution, drying, putting the obtained resin mixture into a forming die, pressing, forming and annealing to obtain an iron-silicon-titanium magnetic powder core, wherein the magnetic permeability is 38.8-61.6 under the conditions of f being 50mT and 50 KHz.

For another example, chinese patent application No. CN201810872226.9 (application date is 2018, 08 and 02), discloses a method for preparing an iron-silicon material and a μ 100 iron-silicon magnetic powder core, which uses water atomized powder, including the following steps: the preparation method comprises the steps of putting Si and Fe into a high-frequency metal smelting furnace for smelting, carrying out water mist method powder preparation on the smelted alloy, carrying out annealing treatment under the protection of inert gas after passing through a 100-mesh sieve, heating the annealed powder in a powder frying machine at the temperature of 80-180 ℃, adding a phosphoric acid solution, continuously frying for 20-60min, carrying out flash evaporation drying, adding a lubricating agent into the dried powder, carrying out compression molding, and uniformly coating paint on the surface of a magnetic core to obtain the magnetic powder core. The component loss of the gas atomized powder is obviously greater than that of the water atomized powder, but the oxygen content of the water atomized powder is far higher than that of the gas atomized powder, the iron loss is improved due to the increase of the oxygen content, the magnetic conductivity performances such as saturation magnetic induction and magnetic conductivity are reduced, and therefore the upper limit of the post-processing performance of the soft magnetic iron core is reduced.

Disclosure of Invention

1. Problems to be solved

Aiming at the defects that the comprehensive performance of the iron-based soft magnetic powder core product is difficult to improve on the existing level due to the defects of atomized iron-based soft magnetic powder and the product forming rate and the qualification rate are generally low when the iron-based soft magnetic powder core product is prepared by adopting the prior art, the invention provides a method for producing the iron-based soft magnetic core based on reduced iron powder alloying. The preparation method provided by the invention has the advantages of simple process and low cost, can effectively reduce the burning loss of alloy components in the smelting process, basically eliminates the defects of satellite powder, surface pits and the like, and avoids the condition of component segregation easily occurring in the solidification process.

2. Technical scheme

In order to solve the problems, the technical scheme adopted by the invention is as follows:

the invention relates to a preparation method for producing an iron-based soft magnetic iron core based on reduced iron powder alloying, which comprises the following steps:

(1) hydrogen reduction of high-purity reduced iron powder: carrying out three-stage hydrogen reduction on iron scale or concentrate powder to obtain high-purity reduced iron powder;

(2) alloying: uniformly mixing the high-purity reduced iron powder obtained in the step (1), alloy powder and a binder according to a certain proportion, and then alloying to obtain iron-based soft magnetic powder;

(3) inorganic insulating coating: carrying out surface inorganic insulation coating treatment on the iron-based soft magnetic powder obtained in the step (2) by using any one of methods such as fluidized gas phase in-situ deposition, simple ball milling, liquid phase deposition and the like to obtain surface inorganic insulation coated iron-based soft magnetic powder;

(4) and (3) pressing and forming: adding the iron-based soft magnetic powder with the surface coated with the inorganic insulation obtained in the step (3) into an acetone resin solution, heating and stirring the mixture, uniformly mixing the mixture with a proper amount of release agent, filling the mixture into a forming die, and performing compression forming under proper pressure to obtain an iron-based soft magnetic composite block;

(5) and (3) heat treatment: and (4) carrying out heat treatment on the iron-based soft magnetic composite block obtained in the step (4) under the protection of inert gas, and cooling along with the furnace to obtain the iron-based soft magnetic iron core.

Furthermore, in the step (1), the granularity of the iron scale or the concentrate powder is 0.1-0.35mm, the obtained high-purity reduced iron powder is dendritic or flat, the apparent density is 2.7-3.0g/cm3, the content of metallic iron is more than or equal to 99.1%, the content of hydrochloric acid insoluble substances is less than or equal to 0.20%, and the granularity of the obtained reduced iron powder is 20-200 mu m;

furthermore, in the step (2), the mass ratio of the reduced iron powder to the alloy powder is 1: (0.02-0.1), wherein the mass ratio of the total mass of the reduced iron powder and the alloy powder to the binder is 1: (0.01-0.02); the alloy powder is one or more of silicon, aluminum, molybdenum, boron, chromium, nickel, copper, manganese and the like, the granularity of the alloy powder is 0.5-5 mu m, and the binder is one of polyethylene or polypropylene.

Furthermore, in the step (2), alloying is carried out in a protective atmosphere of nitrogen or argon, and the alloying temperature and the alloying time satisfy the following formula:

wherein m is the mass of the alloy powder and the unit is kg; m is the mass of the high-purity reduced iron powder, and the unit is kg; t is alloying time in units of s; t is the alloying temperature, and the unit is; d is the particle size of the iron powder, and the unit is m; the alloying temperature range is 800-1000 ℃; the mixing mode adopts ball milling, the ball milling rotating speed is controlled to be 50-150rpm, and the ball milling time is 5-60 min.

Further, in the step (3), the inorganic insulating layer may be SiO₂、TiO₂、Al₂O₃Or one or more of MgO and the like.

Further, in the step (4), the resin in the acetone resin solution is any one of silicone resin, epoxy resin or phenolic resin, and the mass ratio of the iron-based soft magnetic powder coated with the surface inorganic insulation to the resin is 1: (0.01-0.02), the mass ratio of the resin to the acetone is 1:10, and the mass ratio of the heated and stirred powder to the release agent is 1: (0.05-0.1), the release agent is any one of zinc stearate or magnesium stearate, the temperature of compression molding is 20-30 ℃, the compression pressure is 1500-1700MPa, and the compression time is 5-30 s.

Furthermore, in the step (5), the inert gas is one of nitrogen or argon, the heat treatment process is stress relief annealing and diffusion annealing, the annealing temperature is 900-.

3. Advantageous effects

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

(1) according to the preparation method for producing the iron-based soft magnetic iron core based on reduced iron powder alloying, disclosed by the invention, the preparation process is optimized, particularly, the iron powder, the silicon powder and other powder are mixed by adopting an alloying method, a binder is added, alloying treatment process parameters are designed, atoms such as silicon are infiltrated under high temperature and protective atmosphere, and the problems of component loss, segregation and the like caused by atomization are avoided, so that the magnetic saturation strength of the iron-based soft magnetic iron core is improved. In addition, the invention improves the process in the powder preparation stage, and the purity of the iron powder can be greatly improved (the purity can reach 99.3-99.8%) by using the hydrogen reduced iron powder, so that the content of other elements in the iron powder is effectively reduced, the influence of other elements on the performance of the iron-based magnetic powder core can be reduced, and the magnetic performance of the obtained product is improved.

(2) According to the preparation method for producing the iron-based soft magnetic iron core based on reduced iron powder alloying, the process parameters of alloying treatment are optimally designed, particularly, the mixture ratio of alloying material components, the temperature and the time of alloying treatment are strictly controlled, the content of the infiltration element and the thickness of an infiltration layer can be better controlled during siliconizing, and the solid solution combination of silicon powder and iron powder is ensured, so that the control of the content of the iron-based soft magnetic powder is realized, and the magnetic conductivity of the obtained product is further improved.

(3) According to the preparation method for producing the iron-based soft magnetic iron core based on reduced iron powder alloying, provided by the invention, the annealing time and the annealing temperature are comprehensively designed by adopting a mode of combining diffusion annealing and stress relief annealing, so that on one hand, the components of magnetic powder core crystal grains can be more homogenized, and the magnetic conductivity is increased; on the other hand, the stress between the pressed crystal grains can be eliminated, the diffusion annealing and the stress relief annealing treatment are combined into a whole, the performance of the magnetic powder core can be improved, the process is simpler and more convenient, the time is shorter, and the cost is saved.

Drawings

FIG. 1 is an SEM photograph of an iron-based soft magnetic powder obtained after alloying according to the present invention;

FIG. 2 is an SEM photograph of the iron-based magnetic powder core obtained in the present invention;

fig. 3 is a graph showing the results of measuring the saturation induction and permeability of the iron-based magnetic powder cores obtained in the examples and comparative examples of the present invention.

Detailed Description

The invention relates to a method for producing an iron-based soft magnetic iron core based on reduced iron powder alloying, which comprises the following steps:

(1) reduction of high purity reduced iron powder

Performing three-stage hydrogen reduction on iron scale or concentrate powder with the particle size of 0.1-0.35mm to obtain high-purity reduced iron powder, wherein the high-purity reduced iron powder is dendritic or flat, the particle size is 20-200 mu m, and the apparent density is 2.7-3.0g/cm³The content of metallic iron is more than or equal to 99.1 percent, and the content of hydrochloric acid insoluble substances is less than or equal to 0.20 percent. By adopting three sections of hydrogen to directly reduce iron phosphorus or concentrate powder, the purity of the iron powder can be greatly improved (the purity can reach 99.3-99.8%), the influence of other elements in the iron powder on the performance of the iron-based magnetic powder core is effectively reduced, and the magnetic performance of the obtained product is favorably improved.

(2) Alloying

Mixing the reduced iron powder and the alloy powder in the step (1) according to a mass ratio of 1: (0.02-0.1), wherein the mass ratio of the total mass of the reduced iron powder and the alloy powder to the binder is 1: (0.01-0.02) proportioning, performing ball milling treatment, controlling the ball milling rotation speed to be 50-150rpm, performing ball milling for 5-60min, uniformly mixing, and performing alloying treatment in a nitrogen or argon protective atmosphere, wherein the alloy powder adopts any one or the combination of more than two of silicon, aluminum, molybdenum, boron, chromium, nickel, copper, manganese and the like, and the granularity of the alloy powder is controlled to be 0.5-5 mu m; the adhesive is one of polyethylene or polypropylene.

In the case of the atomization melting, because the melting temperatures of the respective alloys are different, the components melted at a lower temperature are burnt out to a certain extent because the melting temperature is higher than the melting temperature, and during the melting, the distribution of the components is not uniform due to the convection of the solution and the chilling during the rapid ejection, so that segregation and the phenomena of satellite powder and surface pits are easily caused. The applicant forms a solid solution by combining one or more alloys and the iron-based powder to form alloying, so that the loss of components is avoided, the components are more homogenized, and the magnetic conductivity can be effectively improved. Meanwhile, the amount of the alloy to be infiltrated is related to the alloying time, temperature and the grain size of the powder, and the applicant finds through research that when the alloying temperature and time satisfy the following formula:

wherein m is the mass of the alloy powder and the unit is kg; m is the mass of the high-purity reduced iron powder, and the unit is kg; t is alloying time in units of s; t is the alloying temperature, and the unit is; d is the particle size of the iron powder in m. Value in the formula (1.2X 10)^-4～6×10^-4)、(4.8×10⁴～5.5×10⁴) The selection of the pre-alloyed iron powder is determined according to the pre-alloyed components and historical experimental data, corresponding numerical values can be selected according to different pre-alloyed components, and specifically, after the pre-alloyed components are selected, the selection of the pre-alloyed components is determined according to the diffusion activation energy required by the pre-alloyed components for infiltrating the iron powder (1.2 multiplied by 10)^-4～6×10^-4) And (4.8X 10)⁴～5.5×10⁴) And selecting two range values. When the diffusion activation energy of the prealloyed component is large, the range value is (1.2 multiplied by 10)^-4～6×10^-4) Selecting smaller value, (4.8X 10)⁴～5.5×10⁴) Larger values are selected, whereas the range values (1.2X 10)^-4～6×10^-4) Selecting larger value, (4.8X 10)⁴～5.5×10⁴) A smaller value is selected. Secondly, the optimal alloying temperature and the optimal alloying time can be determined through the formula, the quality of the alloy powder and the iron powder is the quality of actual use, the optimal alloying treatment temperature which can be determined according to the formula is 800-.

(3) Inorganic insulating coating

Carrying out in-situ deposition on the iron base obtained in the step (2) by utilizing any one of methods such as fluidized gas phase in-situ deposition, simple ball milling, liquid phase deposition and the likeAnd performing surface inorganic insulation coating treatment on the soft magnetic powder to obtain iron-based soft magnetic powder with the surface coated by the inorganic insulation. The coated inorganic insulating layer may be SiO₂、TiO₂、Al₂O₃Or one or more of MgO and the like.

(4) Press forming

Adding the iron-based soft magnetic powder with the surface coated by the inorganic insulation obtained in the step (3) into an acetone resin solution, wherein the resin in the acetone resin solution is any one of organic silicon resin, epoxy resin or phenolic resin, and the mass ratio of the iron-based soft magnetic powder with the surface coated by the inorganic insulation to the resin is 1: (0.01-0.02) and the mass ratio of the resin to the acetone is 1: 10. Heating and stirring, and then mixing with a release agent in a mass ratio of 1: (0.05-0.1) and putting the mixture into a forming die after uniformly mixing, wherein the release agent is any one of zinc stearate or magnesium stearate. And (3) performing compression molding under the conditions that the compression pressure is 1500-1700MPa and the compression temperature is 20-30 ℃, wherein the compression time is 5-30s, and obtaining the iron-based soft magnetic composite block.

(5) Thermal treatment

And (4) performing stress relief annealing and diffusion annealing treatment on the iron-based soft magnetic composite block obtained in the step (4) under the protection of inert gas, wherein the inert gas is one of nitrogen or argon, and cooling along with the furnace to obtain the iron-based soft magnetic iron core.

It should be noted that, because the pressed magnetic powder core has internal stress, internal cracking easily occurs during use, which results in damage of the magnetic powder core, and the residual stress generated by cold-hot deformation among crystal grains can be effectively eliminated by performing stress relief annealing on the magnetic powder core. The invention optimizes the annealing time and annealing temperature, controls the annealing temperature to be 900 plus one year 1100 ℃, and the annealing time to be 0.5 to 3 hours, combines the diffusion annealing and the stress-relief annealing treatment into a whole, not only can improve the performance of the magnetic powder core, but also has simpler process, shorter time and saved cost.

The invention is further described with reference to specific examples.

Example 1

The method for producing the iron-based soft magnetic iron core based on reduced iron powder alloying of the embodiment comprises the following steps:

step one, carrying out three-stage hydrogen reduction on iron scale or concentrate powder with the particle size of 0.1-0.35mm to obtain high-purity reduced iron powder, wherein the high-purity reduced iron powder is dendritic or flat, the particle size is 20-50 mu m, and the apparent density is 2.7-3.0g/cm³The content of metallic iron is more than or equal to 99.1 percent, the content of hydrochloric acid insoluble substances is less than or equal to 0.20 percent,

step two, uniformly mixing the high-purity reduced iron powder, silicon powder (the granularity is 0.5-1 mu m) and polyethylene obtained in the step one, wherein the mass ratio of the reduced iron powder to the silicon powder is 1: 0.07, the mass ratio of the total mass of the reduced iron powder and the silicon powder to the polyethylene is 1: 0.016, controlling the ball milling speed at 100rpm, the ball milling time at 30min, uniformly mixing, and carrying out alloying treatment under the protective atmosphere of argon, wherein the alloying temperature is 800 ℃ and the alloying time duration is 4.5 h.

Step three, carrying out surface inorganic insulation coating treatment on the iron-based soft magnetic powder obtained in the step two by adopting a fluidized gas phase in-situ deposition method to obtain the iron-based soft magnetic powder with the surface coated by inorganic insulation, wherein the coated inorganic insulation layer is SiO₂。

Step four, adding the iron-based soft magnetic powder with the surface coated by the inorganic insulation obtained in the step three into an acetone solution containing organic silicon resin, heating and stirring, wherein the mass ratio of the iron-based soft magnetic powder with the surface coated by the inorganic insulation to the organic silicon resin is 1: 0.01, and the mass ratio of the organic silicon resin to the acetone is 1: 10. Heating and stirring, and mixing with zinc stearate in a mass ratio of 1: 0.05, uniformly mixing, filling into a forming die, controlling the pressing pressure to be 1600MPa, the pressing temperature to be 27 ℃, and the pressing time to be 15s, thus obtaining the iron-based soft magnetic composite block.

And fifthly, performing stress relief annealing and diffusion annealing treatment on the iron-based soft magnetic composite block obtained in the fourth step under the protection of inert gas, wherein the inert gas is argon, the annealing temperature is controlled to be 900 ℃, the annealing time is 3 hours, and the iron-based soft magnetic iron core is obtained after annealing is completed and is cooled along with a furnace.

The magnetic properties of the obtained iron-based soft magnetic core were measured, and the specific results are shown in fig. 3.

Example 2

The method for producing the iron-based soft magnetic iron core based on reduced iron powder alloying of the embodiment comprises the following steps:

step one, carrying out three-stage hydrogen reduction on iron scale or concentrate powder with the particle size of 0.1-0.35mm to obtain high-purity reduced iron powder, wherein the high-purity reduced iron powder is dendritic or flat, the particle size is 100-³The content of metallic iron is more than or equal to 99.1 percent, the content of hydrochloric acid insoluble substances is less than or equal to 0.20 percent,

step two, uniformly mixing the high-purity reduced iron powder obtained in the step one with silicon powder (the granularity is 1-3 mu m) and polypropylene, wherein the mass ratio of the reduced iron powder to the silicon powder is 1: 0.02, wherein the mass ratio of the total mass of the reduced iron powder and the silicon powder to the polypropylene is 1: 0.01, controlling the ball milling rotation speed to be 150rpm, controlling the ball milling time to be 5min, uniformly mixing, and carrying out alloying treatment under the protective atmosphere of nitrogen, wherein the alloying temperature is 900 ℃ and the alloying time duration is 12 h.

Step three, carrying out surface inorganic insulation coating treatment on the iron-based soft magnetic powder obtained in the step two by adopting a simple ball milling method to obtain the iron-based soft magnetic powder with the surface coated by inorganic insulation, wherein the coated inorganic insulation layer is Al₂O₃。

Step four, adding the iron-based soft magnetic powder with the surface coated by the inorganic insulation obtained in the step three into an acetone solution containing epoxy resin, heating and stirring, wherein the mass ratio of the iron-based soft magnetic powder with the surface coated by the inorganic insulation to the epoxy resin is 1: 0.02, and the mass ratio of the epoxy resin to the acetone is 1: 10. Heating and stirring, and mixing with magnesium stearate in a mass ratio of 1: 0.07, uniformly mixing, filling into a forming die, controlling the pressing pressure to be 1700MPa, the pressing temperature to be 20 ℃, and the pressing time to be 5s, thus obtaining the iron-based soft magnetic composite block.

And fifthly, performing stress relief annealing and diffusion annealing treatment on the iron-based soft magnetic composite block obtained in the fourth step under the protection of inert gas, wherein the inert gas is nitrogen, the annealing temperature is controlled to be 1100 ℃, the annealing time is 0.5h, and the iron-based soft magnetic iron core is obtained after annealing is completed and is cooled along with a furnace.

The magnetic properties of the obtained iron-based soft magnetic core were measured, and the specific results are shown in fig. 3.

Example 3

The method for producing the iron-based soft magnetic iron core based on reduced iron powder alloying of the embodiment comprises the following steps:

step one, carrying out three-stage hydrogen reduction on iron scale or concentrate powder with the particle size of 0.1-0.35mm to obtain high-purity reduced iron powder, wherein the high-purity reduced iron powder is dendritic or flat, the particle size is 50-100 mu m, and the apparent density is 2.7-3.0g/cm³The content of metallic iron is more than or equal to 99.1 percent, the content of hydrochloric acid insoluble substances is less than or equal to 0.20 percent,

step two, uniformly mixing the high-purity reduced iron powder, silicon powder (the granularity is 4-5 mu m) and polyethylene obtained in the step one, wherein the mass ratio of the reduced iron powder to the silicon powder is 1: 0.1, wherein the mass ratio of the total mass of the reduced iron powder and the silicon powder to the polyethylene is 1: 0.02, controlling the ball milling rotation speed to be 50rpm, controlling the ball milling time to be 60min, uniformly mixing, and carrying out alloying treatment under the protective atmosphere of nitrogen or argon, wherein the alloying temperature is 1000 ℃, and the alloying time duration is 7 h.

Step three, carrying out surface inorganic insulation coating treatment on the iron-based soft magnetic powder obtained in the step two by adopting a liquid phase deposition method to obtain the iron-based soft magnetic powder with the surface coated by inorganic insulation, wherein the coated inorganic insulation layer is TiO₂。

Step four, adding the iron-based soft magnetic powder with the surface coated by the inorganic insulation obtained in the step three into an acetone solution containing organic silicon resin, heating and stirring, wherein the mass ratio of the iron-based soft magnetic powder with the surface coated by the inorganic insulation to the organic silicon resin is 1: 0.015, and the mass ratio of the organic silicon resin to the acetone is 1: 10. Heating and stirring, and mixing with zinc stearate in a mass ratio of 1: 0.1, uniformly mixing, filling into a forming die, controlling the pressing pressure to be 1600MPa, the pressing temperature to be 30 ℃, and the pressing time to be 30s, thus obtaining the iron-based soft magnetic composite block.

And step five, performing stress relief annealing and diffusion annealing treatment on the iron-based soft magnetic composite block obtained in the step four under the protection of inert gas, adopting nitrogen for protection, controlling the annealing temperature to be 1050 ℃ and the annealing time to be 2 hours, and cooling along with the furnace after the annealing is completed to obtain the iron-based soft magnetic iron core.

The magnetic properties of the obtained iron-based soft magnetic core were measured, and the specific results are shown in fig. 3.

Comparative example 1

The iron-based soft magnetic core of this comparative example was produced in a manner substantially similar to that of example 1, and the main difference was that: the alloying temperature is 700 ℃, and the formula of the invention is not satisfied.

The magnetic properties of the obtained iron-based soft magnetic core were measured, and the specific results are shown in fig. 3.

Comparative example 2

The iron-based soft magnetic core of this comparative example was produced in a manner substantially similar to that of example 2, and the main differences were: the alloying time is 8h, which does not satisfy the formula of the invention.

The magnetic properties of the obtained iron-based soft magnetic core were measured, and the specific results are shown in fig. 3.

Comparative example 3

The iron-based soft magnetic core of this comparative example was produced in a manner substantially similar to that of example 3, and the main difference was that: the annealing temperature is 800 ℃, the annealing time is 4 hours, and the annealing treatment requirement of the invention is not satisfied.

The magnetic properties of the obtained iron-based soft magnetic core were measured, and the specific results are shown in fig. 3.

According to the data in fig. 3, the saturation induction is higher than that of the comparative example, and the magnetic performance is better.