CN111370197B

CN111370197B - Preparation method of iron-silicon soft magnetic powder

Info

Publication number: CN111370197B
Application number: CN201911300325.0A
Authority: CN
Inventors: 李军华; 孙永阳
Original assignee: Hengdian Group DMEGC Magnetics Co Ltd
Current assignee: Hengdian Group DMEGC Magnetics Co Ltd
Priority date: 2019-12-16
Filing date: 2019-12-16
Publication date: 2021-02-09
Anticipated expiration: 2039-12-16
Also published as: CN111370197A

Abstract

The invention relates to the technical field of metal-based soft magnetic materials, and provides a preparation method of iron-silicon soft magnetic powder, aiming at solving the problems of high energy consumption, poor comprehensive performance of magnetic powder, harsh process requirements, complex route and coarse particle size in the traditional preparation process of the iron-silicon soft magnetic powder, which comprises the following steps: (1) adding a dispersing agent and a dispersing agent into the iron oxide red and the ferrosilicon powder, and uniformly mixing to obtain slurry; (2) spray granulation; (3) heat treatment; (4) performing reduction heat treatment (5), adding metal calcium and a dispersing agent, and sintering at high temperature; (6) washing in water, washing in phosphoric acid solution, vacuum drying, annealing, cooling and sieving to obtain soft iron-silicon powder. The preparation method has no special requirements on equipment, low cost, fine particle size and excellent loss performance, and the powder prepared by the method has finer particle size, so the loss performance is excellent, and the powder is an ideal raw material powder for manufacturing the iron-silicon magnetic powder core.

Description

Preparation method of iron-silicon soft magnetic powder

Technical Field

The invention relates to the technical field of metal-based soft magnetic materials, in particular to a preparation method of iron-silicon soft magnetic powder.

Background

The soft magnetic material is an important basic functional material in the development of modern economic society, plays the role of energy transfer conversion and coupling in devices, has the function of electromagnetic conversion, and is widely applied to the fields of communication, power equipment, information technology, automatic control and the like. The soft magnetic material can be divided into metal soft magnetic material, soft magnetic composite material and ferrite soft magnetic material. The soft magnetic composite material is prepared into magnetic powder cores in different shapes by carrying out insulating coating, annealing, pressing and forming on metal soft magnetic powder particles and the like. Therefore, the manufacturing technology of the metal soft magnetic powder is the basis for preparing the magnetic powder core with good performance.

The metal soft magnetic material of the iron-silicon soft magnetic material has lower eddy current loss than a pure iron soft magnetic material, keeps high saturation magnetic inductive strength, is composed of iron and silicon metals, and can effectively reduce eddy current loss due to the fact that the resistivity of the alloy is improved due to the addition of the non-metallic element silicon. And the addition of silicon reduces the magnetocrystalline anisotropy and magnetostriction coefficient of the ferrosilicon alloy, thereby reducing the coercive force and the hysteresis loss of the magnetic core, and being applied to high-power reactors, current resistors, inverters and the like.

The existing method for preparing the iron-silicon soft magnetic powder mainly comprises an ingot casting method, a water atomization method, a gas atomization method and a rapid cooling method. The ingot casting method is to finely crush the well cast block alloy through multi-stage crushing to obtain alloy powder, and the method has long process period and high process cost. The water atomization method utilizes high-pressure water flow to act on molten metal alloy to generate spray atomization, so that the metal alloy forms fine powder. The gas atomization method is characterized in that inert gas flow with certain air pressure and flow velocity acts on molten metal alloy flow, the kinetic energy of the gas flow is converted into the surface energy of liquid metal alloy, and the metal alloy is crushed to form fine metal liquid drops, and the fine metal liquid drops are rapidly cooled and solidified to obtain alloy powder. The alloy powder prepared by the method is in a regular spherical shape, the loss is lower than that of a water atomization method, but the powder magnetic conductivity is lower than that of the water atomization method. The rapid cooling method is to cast the melted mother alloy on a water-cooled copper rod to obtain a thin microcrystalline strip, and then to perform ball milling and fine crushing to obtain alloy powder. Currently, gas atomization and water atomization are widely used. The iron-silicon magnetic core has high saturation magnetic induction intensity and good direct current bias characteristic, has low material cost and performance and can fill the gap between the iron powder core and other metal magnetic powder cores compared with the iron powder core and other metal magnetic powder cores, has unique advantages and has wider application field.

The Chinese patent literature discloses 'iron-silicon soft magnetic powder and a preparation method thereof', the application publication number of which is CN102982955A, the iron-silicon soft magnetic alloy powder comprises silicon and iron, and a small amount of boron is added for improving the plasticity of the material, so that the magnetic powder is subjected to ball milling and flattening treatment, firstly, the raw material is smelted by a medium-frequency vacuum furnace to obtain alloy blocks, the alloy blocks are crushed into alloy small blocks, the powder is subjected to refining grinding by a ball mill and then is subjected to heat treatment to obtain the iron-silicon soft magnetic powder. The preparation method belongs to an ingot casting method, the preparation process cost is high, and the magnetic property is not good although the improvement is not good.

The Chinese patent document discloses a silicon steel magnetic powder core and a preparation method thereof, the application publication number of which is CN107424706A, the preparation process of the silicon steel magnetic powder of the invention is that a vacuum smelting furnace is adopted to prepare silicon steel alloy powder with target components by a water atomization or gas atomization method, the silicon steel alloy powder is screened to be below 100 microns to obtain magnetic powder for manufacturing the magnetic powder core, and the silicon steel magnetic powder core is prepared by the working procedures of passivation, cladding, pressing, heat treatment and the like. The method for preparing magnetic powder belongs to an atomization method, and although the performance of a magnetic powder core is improved through improvement of a coating process, the particle diameter of the powder obtained by the powder preparation process is thick, so that the powder is difficult to obtain good balance in the aspects of loss, saturation magnetic induction intensity and magnetic conductivity, and the overall performance is not high.

Chinese patent literature discloses a method for preparing FeSi alloy powder with high direct current superposition characteristics, and the application publication number of the method is CN 110039060A. The method improves the smelting process, and adopts a non-vacuum smelting process to improve the sequence of smelting iron and silicon. The ferrosilicon alloy powder prepared by the method is spherical, the magnetic permeability is not high, and the loss is higher due to the thickness of D50.

Disclosure of Invention

The invention provides a method for preparing iron-silicon soft magnetic powder, which has no special requirement on equipment, low cost, fine particle size and excellent loss performance and aims to solve the problems of high energy consumption, poor comprehensive performance of magnetic powder, strict process requirement, complex route and coarse particle size in the traditional preparation process of iron-silicon soft magnetic powder.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for preparing an iron-silicon soft magnetic powder, comprising the steps of:

(1) adding a dispersing agent and a dispersing agent into the iron oxide red and the ferrosilicon powder, and uniformly mixing to obtain slurry; the mixing in the step is to uniformly mix the raw materials by grinding, and the mixing equipment can be a sand mill or a ball mill; the silicon source is preferably ferrosilicon powder, on one hand, based on material cost, and on the other hand, because the melting point of the ferrosilicon is greatly lower than that of silicon, the solid phase diffusion reaction is favorably carried out at a lower sintering temperature, and the energy consumption is favorably reduced;

(2) carrying out spray granulation on the slurry to obtain a granulation material;

(3) carrying out heat treatment on the granulated material in an inert atmosphere; the heat treatment is to better combine the two phases after being uniformly mixed and promote the mutual fusion of crystal grains, and the heat treatment equipment can be a bell jar furnace or a pushed slab kiln and only needs equipment capable of performing inert gas protection;

(4) carrying out reduction heat treatment on the granulated material treated in the step (3) in a reducing gas atmosphere to obtain powder; the reduction heat treatment is to reduce the iron oxide in the uniformly mixed material into metallic iron, and the reduction medium can be pure hydrogen, carbon monoxide, ammonia decomposition gas and other reducing gases; the reduction equipment can be a rotary kiln which can be communicated with a reduction atmosphere or a vacuum tube furnace;

(5) adding metal calcium and a dispersing agent into the powder, uniformly mixing, sintering at a high temperature, and cooling to obtain an iron-silicon alloy block; the high-temperature sintering is to carry out solid-phase diffusion alloying reaction on the reduced metallic iron and silicon, and carry out reduction diffusion reaction on the remaining unreduced iron oxide by using a metallic calcium reducing agent; the addition of the collapsing agent is to ensure that the porous block alloy after high-temperature sintering can be rapidly collapsed into fine powder particles by the rapid reaction of the collapsing agent and water after being put into water;

(6) putting the iron-silicon alloy block into water for primary washing, then putting the iron-silicon alloy block into a phosphoric acid solution for secondary washing, and after vacuum drying, annealing, cooling and sieving to obtain iron-silicon soft magnetic powder; the washing function is to remove the reducing agent after the high-temperature solid-phase diffusion reaction, the metal calcium is reduced to become calcium oxide, the calcium oxide becomes calcium hydroxide when meeting water and is separated from the powder during the primary washing, the slurry formed after the collapsibility is repeatedly washed by water and the upper hydroxide is removed, most of the hydroxide can be removed, and then the slurry is put into phosphoric acid solution for secondary washing, so that the residual hydroxide can be removed, the iron-silicon alloy can be pre-passivated, and the oxidation of the powder is avoided. The washing process was repeated with the following steps: the mixture was stirred and left to stand to remove the upper white liquid.

Compared with the existing powder preparation method, the method has the advantages that required equipment is simple, smelting equipment is not needed, the process cost is lower, the prepared magnetic powder is not spherical in an atomization method or sharp irregular in an ingot casting method but is between the spherical magnetic powder and the ingot casting method, the requirement of high magnetic conductivity in high-density manufacturing through compression molding can be met, the magnetic performance is influenced due to the fact that resistivity caused by the fact that a sharp piercing coating layer is reduced in an insulation coating process, and meanwhile, the powder prepared by the method has finer granularity, so that the loss performance is excellent, and the method is ideal raw material powder for manufacturing iron-silicon magnetic powder cores.

Preferably, in the step (6), the ferrosilicon alloy block is directly put into a phosphoric acid solution for washing, a washing process is omitted, water in the phosphoric acid solution is directly used for reacting with calcium oxide, water consumption is saved, and production cost is reduced.

Preferably, in the step (6), the ferrosilicon alloy ingot is alternately washed in a phosphoric acid solution, water, and a phosphoric acid solution. The washing effect is better by alternate washing.

Preferably, in the step (1), the particle size D50 of the iron oxide red is 3-10 μm, and the purity is not less than 99%.

Preferably, in the step (1), the iron content of the ferrosilicon powder is 15-75%; the total content of ferrosilicon in the ferrosilicon powder is more than or equal to 99 percent; the mesh number of the ferrosilicon powder is 500-1000 meshes, more preferably 1000 meshes, and the mesh number is matched with the particle size of the iron oxide red.

Preferably, in the step (1), the particle diameter D50 of the slurry is 1 to 3 μm.

Preferably, in the step (6), the mass percentage of silicon in the iron-silicon soft magnetic powder is 6.0-6.7%, and the balance is iron; in the step (1), the addition amount of the iron oxide red and the ferrosilicon powder is determined according to the ferrosilicon content of the ferrosilicon soft magnetic powder product.

Preferably, in the step (1), the dispersant is one or two selected from calcium gluconate, sorbitol and polyacrylic acid; the addition amount of the dispersing agent in the slurry is 0.2-1.5 wt%. When the addition amount of the dispersing agent is too large, part of the dispersing agent may remain in the dispersing agent powder in the sintering process, thereby affecting the magnetic performance; the addition amount of the dispersing agent is too small, so that the surface energy of the slurry powder is reduced, and the grinding aid effect cannot be achieved.

Preferably, in the step (1), the dispersant is one or two selected from water and ethanol.

Preferably, in the step (3), the oxygen content of the system is controlled to be less than or equal to 450PPM in the heat treatment process; the heat treatment process was carried out according to the following temperature profile:

raising the temperature for 15-80 min at room temperature-100 ℃, and keeping the temperature for 20-120 min at 100 ℃;

heating for 20-120 min at 100-300 ℃, and keeping the temperature for 20-120 min at 300 ℃;

raising the temperature for 200-450 min at 300-1150 ℃, keeping the temperature for 20-120 min at 1150 ℃, and reducing the temperature to room temperature at 1150 ℃.

Preferably, in the step (4), the temperature of the reduction heat treatment is 350-650 ℃; the oxygen content of the powder is less than or equal to 10 wt%; the reduction effect is weak when the temperature is too low, the reduction rate of reducing iron oxide into metal is low, the growth degree of crystal grains is aggravated when the temperature is too high, and the grain size control of the final powder is not facilitated; the reduction rate of the ferric oxide can be tested by an oxygen content tester, and the oxygen content of the powder obtained after the reduction heat treatment is less than or equal to 10 wt%.

Preferably, in the step (5), the high-temperature sintering temperature is 1000-1400 ℃, and the time is 2-8 h.

Preferably, in the step (5), the amount of the calcium metal used is 1.0 to 1.4 times of the reaction equivalent, the amount of the calcium metal used is a certain amount of volatilization based on the calcium metal, excessive calcium metal is added to cause waste and increase economic cost, and too little calcium metal is added to reduce the remaining iron oxide into the iron metal completely.

Preferably, in the step (5), the collapsing agent is calcium oxide or calcium chloride; the addition amount of the collapsing agent in the powder is 0.5-4.5 wt%.

Preferably, in the step (6), the concentration of the phosphoric acid solution is 0.15 to 2.0 wt%. The low concentration of the phosphoric acid solution can lead to incomplete hydroxide reaction and bring impurities to influence the magnetic property of the alloy powder, and the high concentration of the phosphoric acid solution causes violent reaction, consumes a large amount of alloy powder and has low yield. When the alloy block is put into the phosphoric acid solution with low concentration in the concentration range, hydroxide can be reacted while passivation is carried out, and meanwhile, the powder is effectively prevented from being slowly oxidized in water.

Therefore, the invention has the following beneficial effects: the preparation method has the advantages of simple required equipment, no need of smelting equipment and lower process cost, the prepared magnetic powder is not spherical in an atomization method or sharp irregular in an ingot casting method but between the spherical and the ingot casting methods, the requirement of high magnetic conductivity in high-density manufacturing by pressing and molding can be met, the magnetic performance is influenced by the reduction of resistivity caused by the fact that a sharp shape punctures a coating layer in insulation coating, and meanwhile, the powder prepared by the method has finer granularity, so that the loss performance is excellent and the powder is an ideal raw material powder for manufacturing the iron-silicon magnetic powder core.

Detailed Description

The technical solution of the present invention is further specifically described below by way of specific examples.

In the present invention, all the equipment and materials are commercially available or commonly used in the art, and the methods in the following examples are conventional in the art unless otherwise specified.

Example 1

(1) Weighing iron oxide red with the purity of 99 percent and the grain diameter D50 of 6 mu m and SiFe powder with the iron content of 75 percent (the total content of ferrosilicon is more than or equal to 99 percent) of 1000 meshes according to the proportion of the components of the final iron-silicon soft magnetic powder (6.0 percent of silicon and the balance of iron), adding the weighed iron-silicon soft magnetic powder into a sand mill, adding sorbitol with the total mass of 0.8 percent of the slurry as a dispersing agent, adding water with the volume of 60 percent of the sand mill as a dispersing agent, and sanding for 5 hours to obtain the slurry with the grain diameter D50 of 2 mu m;

(2) pumping the slurry into a spray tower through a pump for spray granulation to obtain granules;

(3) loading the granulated material into a sagger and placing the sagger into a bell jar furnace, pumping air out of the bell jar furnace, and then filling nitrogen for heat treatment, wherein the treatment temperature curve is room temperature-100 ℃ temperature rise time 15min, 100 ℃ heat preservation 120min, 100 ℃ to 300 ℃ temperature rise time 120min, 300 ℃ heat preservation 20min, 300 ℃ to 1150 ℃ temperature rise time (400min), 1150 ℃ heat preservation time 20min, and furnace cooling to room temperature after 1150 ℃ heat preservation; controlling the oxygen content of the system to be less than or equal to 450PPM in the heat treatment process;

(4) putting the heat-treated powder into a rotary kiln, vacuumizing, filling hydrogen, and treating at 500 ℃ for 5 hours at the kiln rotation speed of 1 r/min to obtain powder; taking out the powder after furnace cooling to detect that the oxygen content is 8%;

(5) uniformly mixing powder, 1.4 times of reaction equivalent calcium and calcium oxide accounting for 3.0 wt% of the powder by using a mixer, putting the mixture into a vacuum furnace for high-temperature solid-phase diffusion reaction, setting the temperature of the vacuum furnace to be 1000 ℃, keeping the temperature for 8 hours, and then cooling the mixture along with the furnace to obtain an iron-silicon alloy block;

(6) putting the ferrosilicon alloy block into water for primary washing, changing calcium oxide into calcium hydroxide when the calcium oxide is in water and separating the calcium hydroxide from powder, repeatedly washing slurry formed after the collapsibility with water and removing upper hydroxide, removing most of the hydroxide, then putting the slurry into 3.5 wt% phosphoric acid solution for secondary washing, removing the rest hydroxide, forming a passivation layer on the surface of the alloy powder, reducing the powder in a hydrogen atmosphere vacuum furnace at 650 ℃ for 2.5h after vacuum drying, annealing and removing stress, and sieving the powder with a 100-mesh sieve to obtain the ferrosilicon soft magnetic powder.

Example 2

(1) Weighing iron oxide red with the purity of 99 percent and the grain diameter D50 of 3 mu m and SiFe powder with the iron content of 15 percent (the total content of ferrosilicon is more than or equal to 99 percent) of 500 meshes according to the proportion of the components of the final iron-silicon soft magnetic powder (6.5 percent of silicon and the balance of iron), adding the weighed iron-silicon soft magnetic powder into a sand mill, adding calcium gluconate with the total mass of 0.8 percent of the slurry and polyacrylic acid with the total mass of 0.7 percent of the slurry as dispersing agents, adding water with the volume of 60 percent of the sand mill as dispersing agents, and sanding for 5 hours to obtain the slurry with the grain diameter D50 of 1 mu;

(3) loading the granulated material into a sagger and placing the sagger into a bell jar furnace, pumping air out of the bell jar furnace, and then filling nitrogen for heat treatment, wherein the treatment temperature curve is that the temperature rise time is 50min at room temperature and 100 ℃, the temperature is kept at 100 ℃ for 30min, the temperature rise time is 60min at 100 ℃ and 300 ℃, the temperature is kept at 300 ℃ for 60min, the temperature rise time is 400min at 300 ℃ and 1150 ℃ for 100min, and the furnace cooling is carried out when the temperature is kept at 1150 ℃ to the room temperature; controlling the oxygen content of the system to be less than or equal to 450PPM in the heat treatment process;

(4) putting the heat-treated powder into a rotary kiln, vacuumizing, filling hydrogen, and treating at 350 ℃ for 5 hours at the kiln rotation speed of 1 r/min to obtain powder; taking out the powder after furnace cooling to detect that the oxygen content is 10%;

(5) uniformly mixing the powder, calcium with reaction equivalent of 1.3 times and calcium chloride accounting for 4.5 percent of the powder by using a mixer, then putting the mixture into a vacuum furnace for high-temperature solid-phase diffusion reaction, setting the temperature of the vacuum furnace to be 1400 ℃, keeping the temperature for 2 hours, and then cooling the mixture along with the furnace to obtain an iron-silicon alloy block;

(6) putting the ferrosilicon alloy block into 0.5% phosphoric acid aqueous solution, repeatedly washing slurry formed after the disintegration with water, removing upper hydroxide, removing most of the hydroxide, then putting the slurry into 2.5% phosphoric acid solution to remove the rest hydroxide, forming a passivation layer on the surface of the alloy powder, after vacuum drying, reducing the powder in a hydrogen atmosphere vacuum furnace at 650 ℃ for 2.5h, annealing and removing stress, and sieving the powder with a 100-mesh sieve to obtain the ferrosilicon soft magnetic powder.

Example 3

(1) Weighing iron oxide red with the purity of 99 percent and the grain diameter D50 of 10 mu m and SiFe powder with the iron content of 55 percent (the total content of ferrosilicon is more than or equal to 99 percent) of 500 meshes according to the proportion of the components of the final iron-silicon soft magnetic powder (6.7 percent, the balance of iron), adding the weighed iron-silicon soft magnetic powder into a sand mill, adding polyacrylic acid with the total mass of 0.2 percent of slurry as a dispersing agent, adding water with the volume of 60 percent of the sand mill as a dispersing agent, and sanding for 5 hours to obtain the slurry with the grain diameter D50 of 3 mu m;

(3) loading the granulated material into a sagger and placing the sagger into a bell jar furnace, pumping air out of the bell jar furnace, and then filling nitrogen for heat treatment, wherein the treatment temperature curve is that the temperature rise time is 80min at room temperature and 100 ℃, the temperature is kept at 100 ℃ for 20min, the temperature rise time is 20min at 100 ℃ and 300 ℃, the temperature is kept at 300 ℃ for 120min, the temperature rise time is 200min at 300 ℃ and 1150 ℃ for 120min, and the furnace cooling is carried out when the temperature is kept at 1150 ℃ to the room temperature; controlling the oxygen content of the system to be less than or equal to 450PPM in the heat treatment process;

(4) putting the heat-treated powder into a rotary kiln, vacuumizing, and filling hydrogen, wherein the rotary speed of the kiln is 1 r/min, the heat treatment temperature is 650 ℃, and the powder is obtained after treatment for 5 hours; taking out the powder after furnace cooling to detect that the oxygen content is 7.5 percent,

(5) uniformly mixing powder, 1.0 time of reaction equivalent calcium and calcium oxide accounting for 0.5 wt% of the powder by using a mixer, putting the mixture into a vacuum furnace for high-temperature solid-phase diffusion reaction, setting the temperature of the vacuum furnace to be 1000 ℃, keeping the temperature for 8 hours, and then cooling the mixture along with the furnace to obtain an iron-silicon alloy block;

(6) and putting the ferrosilicon alloy block into 4.5% phosphoric acid aqueous solution for washing, carrying out vacuum drying, reducing the powder in a hydrogen atmosphere vacuum furnace at 650 ℃ for 2.5h, annealing and removing stress, and sieving the powder by a 100-mesh sieve to obtain ferrosilicon soft magnetic powder.

Comparative example 1

Smelting an industrial pure iron block and a polycrystalline iron block in a vacuum induction furnace, wherein the cast ferrosilicon alloy contains Si 6.7% and the balance of Fe, the smelting temperature is 1500 ℃, the smelting time is 1.5h, the smelted alloy block is firstly coarsely crushed into small blocks and then finely crushed by a jaw crusher, then the small blocks are crushed by a vibrating mill and then reduced for 5h at 1100 ℃ in a hydrogen atmosphere vacuum furnace for annealing and stress removal, and the powder is sieved by a 60-mesh sieve to obtain the ferrosilicon soft magnetic powder.

Comparative example 2

The method comprises the steps of putting industrial pure iron blocks and polycrystalline iron blocks into a vacuum induction furnace for smelting, casting ferrosilicon with the components of Si 6.7% and the balance of Fe at the smelting temperature of 1600 ℃ for 2 hours, casting and atomizing the molten metal alloy, atomizing the molten metal alloy by adopting high-purity nitrogen, refining the alloy liquid cast under the action of high-pressure nitrogen into small liquid drops, quickly condensing the alloy liquid into powder in the falling process, reducing the atomized powder in a hydrogen atmosphere vacuum furnace at 1100 ℃ for 5 hours, annealing and removing stress, and sieving the powder by a 60-mesh sieve to obtain the ferrosilicon soft magnetic powder.

The properties of the iron-silicon soft magnetic powders of examples 1 to 3 and comparative examples 1 to 2 were examined, and the results are shown in table 1:

TABLE 1 Performance test results of the Fe-Si soft magnetic powders of examples and comparative examples

The ferrosilicon soft magnetic powder cores of 60 μ were prepared by passing the ferrosilicon soft magnetic powders of examples 1 to 3 and comparative examples 1 to 2 through the procedures of sieving distribution ratio, surface treatment, insulation coating, press molding, heat treatment, surface coating, etc., and the magnetic properties of the magnetic powder cores were tested, with the results shown in table 2.

TABLE 2 results of measuring properties of the obtained Fe-Si soft magnetic powder cores of examples and comparative examples

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and other variations and modifications may be made without departing from the spirit of the invention as set forth in the claims.

Claims

1. A method for preparing iron-silicon soft magnetic powder is characterized by comprising the following steps:

(1) adding a dispersing agent and a dispersing agent into the iron oxide red and the ferrosilicon powder, and uniformly mixing to obtain slurry; the dispersing agent is selected from one or two of calcium gluconate, sorbitol and polyacrylic acid; the dispersant is selected from one or two of water and ethanol;

(3) carrying out heat treatment on the granulated material in an inert atmosphere;

(4) carrying out reduction heat treatment on the granulated material treated in the step (3) in a reducing gas atmosphere to obtain powder;

(5) adding metal calcium and a dispersing agent into the powder, uniformly mixing, sintering at a high temperature, and cooling to obtain an iron-silicon alloy block; the collapsing agent is calcium oxide or calcium chloride;

(6) and putting the iron-silicon alloy block into water for primary washing, then putting the iron-silicon alloy block into a phosphoric acid solution for secondary washing, and after vacuum drying, annealing, cooling and sieving to obtain the iron-silicon soft magnetic powder.

2. A method of preparing an Fe-Si soft magnetic powder according to claim 1,

in the step (1), the particle size D50 of the iron red is 3-10 mu m, and the purity is more than or equal to 99%; the iron content of the ferrosilicon powder is 15-75%; the total content of ferrosilicon in the ferrosilicon powder is more than or equal to 99 percent; the mesh number of the ferrosilicon powder is 500-1000 meshes; the particle size D50 of the slurry is 1-3 mu m.

3. The method for preparing the iron-silicon soft magnetic powder according to claim 1, wherein in the step (6), the mass percentage of silicon in the iron-silicon soft magnetic powder is 6.0 to 6.7%, and the balance is iron.

4. The method of claim 1, wherein the dispersant is added to the slurry in an amount of 0.2 to 1.5wt% in the step (1).

5. The method for preparing an iron-silicon soft magnetic powder according to claim 1, wherein in the step (3), the oxygen content of the system is controlled to be less than or equal to 450PPM during the heat treatment; the heat treatment process was carried out according to the following temperature profile:

6. The method for preparing an iron-silicon soft magnetic powder according to claim 1, wherein the temperature of the reduction heat treatment in the step (4) is 350 to 650 ℃; the oxygen content of the powder is less than or equal to 10 wt%.

7. The method of claim 1, wherein the high temperature sintering is performed at 1000 to 1400 ℃ for 2 to 8 hours in the step (5).

8. The method of preparing an iron-silicon soft magnetic powder according to claim 1, wherein the amount of the metallic calcium used in the step (5) is 1.0 to 1.4 times the reaction equivalent.

9. The method of claim 1, wherein the amount of the collapsing agent added to the powder in the step (5) is 0.5 to 4.5 wt%.

10. The method of preparing an iron-silicon soft magnetic powder according to claim 1, wherein the concentration of the phosphoric acid solution in the step (6) is 0.15 to 2.0 wt%.