Soft magnetic material and method for producing the same

Abstract

The application provides a soft magnetic material and a preparation method thereof. The preparation method comprises the following steps: mixing iron alloy powder and magnesium oxide-coated carbonyl iron powder, and then sequentially performing granulation, primary pressing, secondary pressing and first annealing treatment on the mixed powder to obtain the soft magnetic material; wherein the pressure in the primary pressing process is lower than the pressure in the secondary pressing process. Based on the preparation method, the soft magnetic material obtained by the application has excellent electromagnetic characteristics and low loss under high-frequency working conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soft magnetic materials, in particular to a soft magnetic material and a preparation method thereof. BACKGROUND

[0002] In recent years, with the rapid development of miniaturization and high frequency of electronic devices, higher requirements are put forward for soft magnetic materials to have high magnetic permeability and low high-frequency loss at the same time, and the traditional metal soft magnetic material and ferrite cannot meet the use requirements, so the soft magnetic composite material enters the field of vision.

[0003] Soft magnetic composite material SMC (Soft Magnetic Composite), also known as magnetic powder core, is a kind of soft magnetic material prepared by insulating coating soft magnetic powder, pressing into the required shape by powder metallurgy process and through heat treatment process, etc., which has the advantages of low eddy current loss, good frequency characteristic, easy to machine, etc., so the soft magnetic composite material has been widely concerned all over the world.

[0004] Soft magnetic composite material combines the advantages of metal and ferrite soft magnetic material, its resistivity is greatly improved compared with soft magnetic metal, which can effectively reduce the eddy current loss, and has higher saturation magnetization than soft magnetic ferrite, which can better meet the requirements of miniaturization and integration of power electronic devices. Moreover, soft magnetic composite material can be pressed into various complex shapes such as ring, E type, U type, etc., realizing the integrated production of components and devices. Therefore, soft magnetic composite material has become the fastest growing magnetic material in development and application, which is used to produce various power electronic key components such as inductors, filters, choke coils and transformers. The high-speed development of modern information technology and power electronics industry not only promotes the development of soft magnetic composite material, but also puts forward higher requirements for the magnetic properties and power loss of soft magnetic composite material. The research on soft magnetic composite material in the international community has always been mainly focused on two main lines, i.e. developing soft magnetic alloy system with specific performance to meet the needs of different application occasions, and innovating insulation coating process to reduce high-frequency loss. Soft magnetic composite material is mainly used in PFC inductors, boost-buck inductors, output filter inductors, power inductors, energy storage inductors, etc. Due to its excellent anti-saturation capability and good high-temperature characteristics, it is gradually replacing other soft magnetic materials and being widely used in inductor devices, laying a good foundation for the miniaturization and reliability of power electronics. With the high-frequency trend of power semiconductors, power electronic devices are developing towards high frequency, high power density, small size and energy saving. Metal soft magnetic elements make up for the performance deficiencies of silicon steel, ferrite and amorphous strip, etc., and the advantages of metal magnetic powder core, such as high magnetic flux density, small size, low noise, strong anti-saturation capability, good frequency and temperature stability, and the ability to process special devices, are highlighted, and the application scenarios are increasingly rich.

[0005] However, the soft magnetic composite material on the market at present has high loss in the MHz level high frequency use environment, and the preparation process is complex, especially the amount of organic glue used is large, and the steps are many. For example, the prior art CN113241246A and the prior art CN110957096A each propose a method for preparing a new soft magnetic powder core, but both of the above-mentioned patents have the problems of complex process for preparing the magnetic powder core, large amount of organic glue used, and high loss under MHz level high frequency conditions. Therefore, it is necessary to propose a completely new preparation method to improve the above-mentioned problems. SUMMARY

[0006] The main purpose of the present application is to provide a soft magnetic material and a preparation method thereof, so as to solve the problems of complex preparation process, large amount of organic glue used, and high loss under MHz level high frequency conditions in the prior art.

[0007] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a preparation method of a soft magnetic material is provided, and the preparation method comprises the following steps: mixing iron alloy powder and magnesium oxide coated carbonyl iron powder, and sequentially performing granulation, primary pressing, secondary pressing and first annealing treatment on the mixed powder to obtain a soft magnetic material; wherein the pressure in the primary pressing process is lower than the pressure in the secondary pressing process.

[0008] Further, the weight ratio of the iron alloy powder and the magnesium oxide coated carbonyl iron powder is (90-98):(2-10).

[0009] Further, the pressure in the primary pressing process is 200-500 MPa; and the pressure in the secondary pressing process is 800-1000 MPa.

[0010] Further, in the first annealing treatment process, the treatment temperature is 500-900 DEG C, and the treatment time is 3-20 h.

[0011] Further, after granulation, the granulated material is mixed with a release agent, and then primary pressing is performed; preferably, the release agent is selected from stearic acid release agents, more preferably the stearic acid release agent is one or more of zinc stearate, aluminum stearate, magnesium stearate, calcium stearate or lithium stearate; preferably, the amount of the release agent is 0.1-2% of the weight of the granulated material.

[0012] Further, the iron alloy powder is prepared by the following method: sequentially performing second annealing treatment, first sieving treatment and insulation treatment on the iron alloy raw material to obtain the iron alloy powder; preferably, the iron alloy raw material is selected from one or more of iron-silicon-cadmium, iron-silicon-molybdenum, iron-silicon-aluminum, iron-nickel or cerium-iron-nitrogen.

[0013] Further, in the second annealing process, the temperature is 500-1000°C and the time is 3-20h; preferably, the particle size of the material after the first sieving process is 20-80μm; preferably, the insulation process comprises mixing the material after the first sieving process, an organic solvent and phosphoric acid, so that the phosphoric acid reacts with the material after the first sieving process and coats the surface of the material to form a phosphating layer, thus obtaining the iron alloy powder; further preferably, in the insulation process, the amount of phosphoric acid is 0.1-6% of the weight of the material after the first sieving process; further preferably, in the insulation process, the organic solvent is an alcohol solvent, more preferably one or more of n-butanol, ethanol, acetone or methanol.

[0014] Further, the magnesium oxide-coated carbonyl iron powder is prepared by the following method: under the condition of a mixed gas of hydrogen and carbon monoxide and a temperature of 300-500°C, the iron powder is chemically reacted to obtain a carbonyl iron powder; the carbonyl iron powder is subjected to a second sieving process to obtain a material after the second sieving process; the material after the second sieving process is mixed with a magnesium acetate aqueous solution, and then water is removed to obtain a magnesium acetate-coated carbonyl iron powder; under the condition of an inert gas atmosphere and a temperature of 300-500°C, the magnesium acetate-coated carbonyl iron powder is subjected to a thermal decomposition reaction to obtain the magnesium oxide-coated carbonyl iron powder.

[0015] Further, the flow rate of the mixed gas is 5-20L / min; preferably, the particle size of the material after the second sieving process is 2-8μm; preferably, the weight ratio of the material after the second sieving process to the magnesium acetate aqueous solution is 100:(1-5); preferably, the time of the thermal decomposition reaction is 20-80min.

[0016] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a soft magnetic material is provided, which is prepared by the above-mentioned method for preparing a soft magnetic material.

[0017] Based on the above-mentioned preparation method, the soft magnetic material obtained by the present application also has excellent electromagnetic properties and low loss under high-frequency working conditions. DETAILED DESCRIPTION

[0018] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments.

[0019] As described in the background section of the present application, there are problems in the prior art, such as complex preparation process, large amount of organic glue used, and high loss under high frequency conditions at MHz level. In order to solve this problem, the present application provides a preparation method of soft magnetic material, which comprises: mixing iron alloy powder and magnesium oxide coated carbonyl iron powder, and then sequentially performing granulation, primary pressing, secondary pressing and first annealing treatment on the mixed powder to obtain a soft magnetic material; wherein the pressure in the primary pressing process is lower than that in the secondary pressing process.

[0020] Generally, when using iron alloy material to prepare soft magnetic material, a large amount of organic glue is added to promote the bonding of iron alloy grains together. However, organic glue is highly polluting and harmful to the human body, and is not environmentally friendly. However, the present inventors have found that by using iron alloy powder and magnesium oxide coated carbonyl iron powder as raw materials, no additional organic glue is needed to mix and prepare a soft magnetic material with high magnetic permeability and low loss under high frequency conditions at MHz level, which is more environmentally friendly. The magnesium oxide coated carbonyl iron powder has good bonding effect, which can bond the iron alloy grains together. At the same time, the magnesium oxide coated carbonyl iron powder is dispersedly distributed between the iron alloy grains, making the low resistivity iron alloy grains discontinuous, thereby improving the resistivity of the soft magnetic material, and effectively reducing the eddy current loss of the material. On the other hand, the magnesium oxide coated carbonyl iron powder has high magnetic permeability, which can further improve the magnetic permeability of the material as a raw material for synthesizing soft magnetic material.

[0021] At the same time, the granulated powder is sequentially subjected to two pressing forming, and the strength of the first pressing forming is less than that of the second pressing forming. The granulated powder is first pressed at low pressure, so that the density of the powder after primary pressing is higher, and the powders in the center position are in a state of close extrusion. After primary pressing, further secondary forming is carried out at high pressure, which more effectively improves the non-uniformity of the powder density distribution, reduces the pressure loss in the secondary pressing forming process, and further improves the mixing effect of the iron alloy powder and the magnesium oxide coated carbonyl iron powder, and the uniformity of the above-mentioned excellent performance of the material. In addition, the above-mentioned preparation method is simpler and easier to operate.

[0022] Based on this, the soft magnetic material prepared by the above-mentioned preparation method has excellent electromagnetic properties and low loss under high frequency working conditions. Specifically, in the subsequent application process, it can be more matched with the third generation wide bandgap semiconductor, and is more suitable for the application requirements in the fields of PFC inductance, step-up and step-down inductance, output filter inductance, power inductance, energy storage inductance, etc.

[0023] In order to further balance the high magnetic permeability and low loss performance of the material, the weight ratio of the iron alloy powder and the magnesium oxide coated carbonyl iron powder is preferably (90-98):(2-10).

[0024] In a preferred embodiment, the pressure in the first pressing process is 200-500 MPa; the pressure in the second pressing process is 800-1000 MPa. Based on this, the non-uniformity of the powder density distribution can be more effectively improved, thereby facilitating better mixing of the ferrous alloy powder and the magnesium oxide-coated carbonyl iron powder, and better uniformity of the above-mentioned excellent performance of the material.

[0025] In a preferred embodiment, in the first annealing process, the treatment temperature is 500-900 °C, and the treatment time is 3-20 h. Based on this, the annealing process of the material is more stable, and the stability of the excellent performance of the material is better.

[0026] In a preferred embodiment, the granulation is performed by passing the mixed powder through an 80-100 mesh sieve to form small granular powder. After the granulation, the granulated material is mixed with a release agent, and then subjected to the first pressing; preferably, the release agent is selected from stearic acid release agents, and more preferably the stearic acid release agent is one or more of zinc stearate, aluminum stearate, magnesium stearate, calcium stearate, or lithium stearate; preferably, the amount of release agent is 0.1-2% of the weight of the granulated material. Mixing the granulated material with a release agent before pressing can further improve the forming performance of the product, thereby further improving the performance uniformity of the product. In a preferred embodiment, the stearic acid release agent can be heated to 100-300 °C (preferably 220 °C) before being mixed with the granulated material. Based on this, the release agent and the granulated material are more uniformly mixed, thereby more effectively avoiding cracking of the material during subsequent pressing.

[0027] Preferably, the ferrous alloy powder is prepared by sequentially subjecting the ferrous alloy raw material to a second annealing process, a first sieving process, and an insulation process to obtain the ferrous alloy powder; preferably, the ferrous alloy raw material is selected from one or more of iron-silicon-cadmium, iron-silicon-molybdenum, iron-silicon-aluminum, iron-nickel, or cerium-iron-nitrogen. Based on this, the selection of the raw material is more cost-effective, and it is more compatible with the magnesium oxide-coated carbonyl iron powder, and the two raw materials have better synergistic effects, resulting in higher magnetic permeability of the material and lower loss under high-frequency current.

[0028] To further improve the stability of the second annealing process and thereby improve the performance stability of the material, preferably, in the second annealing process, the treatment temperature is 500-1000 °C, and the treatment time is 3-20 h.

[0029] To further improve the uniformity of the powder mixture and thereby improve the performance uniformity of the material, preferably, the particle size of the material after the first sieving process is 20-80 μm.

[0030] To further improve the insulation properties of the material, thereby further reducing the eddy current loss of the material, the insulation treatment preferably comprises: mixing the first sieved material, an organic solvent and phosphoric acid, so that the phosphoric acid reacts with the first sieved material and coats the outer surface of the first sieved material to form a phosphating layer, thereby obtaining the ferrous alloy powder. For example, when the ferrous alloy raw material is iron-silicon-cadmium, the material of the phosphating layer can be iron phosphate; when the ferrous alloy raw material is iron-silicon-molybdenum, the material of the phosphating layer can be molybdenum phosphate; when the ferrous alloy raw material is iron-silicon-aluminum, the material of the phosphating layer can be aluminum phosphate; when the ferrous alloy raw material is iron-nickel, the material of the phosphating layer can be nickel phosphate; when the ferrous alloy raw material is cerium-iron-nitrogen, the material of the phosphating layer can be cerium phosphate.

[0031] Further preferably, the amount of phosphoric acid used in the insulation treatment is 0.1-6% of the weight of the first sieved material. Further preferably, the organic solvent used in the insulation treatment is an alcohol solvent, more preferably one or more of n-butanol, ethanol, acetone or methanol, and further preferably n-butanol.

[0032] In a preferred embodiment, the magnesium oxide-coated carbonyl iron powder is prepared by the following method: iron powder is chemically reacted under the condition of a mixed gas of hydrogen and carbon monoxide and a temperature of 300-500°C to obtain carbonyl iron powder; the carbonyl iron powder is subjected to a second sieving treatment to obtain a second sieved material; the second sieved material is mixed with an aqueous solution of magnesium acetate, and then the water is removed to obtain magnesium acetate-coated carbonyl iron powder. The magnesium acetate-coated carbonyl iron powder is subjected to a decomposition reaction under the condition of an inert gas atmosphere and a temperature of 300-500°C to obtain magnesium oxide-coated carbonyl iron powder. Based on this, the obtained magnesium oxide-coated carbonyl iron powder has better performance. On the one hand, its adhesion is better. At the same time, it can be better dispersed between the grains of the ferrous alloy, thereby further improving the resistivity of the soft magnetic material and effectively reducing the eddy current loss of the material. On the other hand, it has better magnetic permeability, and as a raw material for synthesizing soft magnetic materials, it can further improve the magnetic permeability of the material. The way to remove the water can be to place the mixed material in an oven and dry it at a temperature of 50-100°C for 1-3h.

[0033] In a preferred embodiment, the iron powder can be first sent into a high-temperature plasma through a carrier gas, rapidly absorb heat, melt, and under the action of surface tension, polycondense into spherical droplets, enter the cooling chamber, and then rapidly cool and solidify to fix the spheres, thereby obtaining iron powder with high sphericity and good flowability. Then the treated iron powder is mixed with carbon monoxide to obtain carbonyl iron powder.

[0034] Preferably, the mixed gas is introduced at a flow rate of 5-20 L / min. Preferably, the particle size of the material after the second sieving treatment is 2-8 μm. Preferably, the weight ratio of the material after the second sieving treatment to the magnesium acetate aqueous solution is 100:(1-5). Preferably, the time for the thermal decomposition reaction is 20-80 min.

[0035] The application also provides a soft magnetic material prepared by the method.

[0036] Based on the foregoing reasons, the soft magnetic material has high magnetic permeability and low loss in MHz-level high frequency use environment. The soft magnetic material also has excellent electromagnetic properties and low loss under MHz working conditions. Specifically, in subsequent application processes, the soft magnetic material has higher matching degree with the third generation wide band gap semiconductor, and is more suitable for the application requirements in the fields of PFC inductors, step-up and step-down inductors, output filter inductors, power inductors, energy storage inductors, etc.

[0037] The application will be further described in detail below in combination with specific examples, which should not be understood as limiting the scope of the application.

[0038] Example 1

[0039] (1) Iron-silicon-aluminum is selected as the raw material powder.

[0040] (2) The raw material powder is annealed in a tube furnace under the protection of a nitrogen atmosphere at a temperature of 650℃ for 16 h.

[0041] (3) The annealed raw material powder is sieved through a 500-mesh sieve to obtain a powder with an average particle size of 25 μm.

[0042] (4) The sieved powder is subjected to insulation treatment. 1% phosphoric acid is added to n-butanol as a solvent, and the mixture is thoroughly mixed, heated and stirred until completely dry, and sieved for use.

[0043] (5) The iron powder is sent into a high-temperature plasma through a carrier gas, rapidly absorbs heat, melts, and polymerizes into spherical droplets under the action of surface tension, enters a cooling chamber, and is rapidly cooled and solidified to fix the spheres, thereby obtaining iron powder with high sphericity and good flowability.

[0044] (6) The above iron powder is treated in a tube furnace under a mixed atmosphere of hydrogen and carbon monoxide at a temperature of 380℃, thereby obtaining carbonyl iron powder.

[0045] (7) The above carbonyl iron powder is sieved to obtain carbonyl iron powder with a particle size of 5 μm.

[0046] (8) The above carbonyl iron powder, n-butanol and magnesium acetate solution are thoroughly mixed and stirred in an ultrasonic stirrer, and dried in an oven at 80℃ for 2 h.

[0047] (9) The magnesium acetate coated carbonyl iron powder is decomposed in a tube furnace under argon atmosphere at 450°C for 60 minutes to obtain a magnesium oxide coated carbonyl iron powder.

[0048] (10) The raw material powder with 98% by weight and 25 μm in particle size is mixed with 2% by weight of carbonyl iron powder with 5 μm in particle size in a plastic ball mill tank with zirconium balls and the powder in a weight ratio of 1.5:1 for 2 minutes to obtain a uniformly mixed powder.

[0049] (11) The uniformly mixed powder is granulated.

[0050] (12) 0.8% of zinc stearate release agent is heated to 220°C and then mixed with the granulated powder.

[0051] (13) The prepared powder is once pressed into a magnetic powder core under a low pressure of 400 MPa.

[0052] (14) The magnetic powder core pressed under a low pressure is twice pressed under a pressure of 1000 MPa.

[0053] (15) The magnetic powder core obtained by twice pressing is annealed in a tube furnace under nitrogen atmosphere at a temperature of 780°C for 5 hours to obtain a soft magnetic material.

[0054] Example 2

[0055] The difference between Example 1 and Example 2 is that in step (10), 97% by weight of raw material powder with 25 μm in particle size is mixed with 3% by weight of carbonyl iron powder with 5 μm in particle size.

[0056] Example 3

[0057] The difference between Example 1 and Example 3 is that in step (10), 96% by weight of raw material powder with 25 μm in particle size is mixed with 4% by weight of carbonyl iron powder with 5 μm in particle size.

[0058] Example 4

[0059] The difference between Example 1 and Example 4 is that in step (10), 95% by weight of raw material powder with 25 μm in particle size is mixed with 5% by weight of carbonyl iron powder with 5 μm in particle size.

[0060] Example 5

[0061] The difference between Example 1 and Example 5 is that in step (10), 94% by weight of raw material powder with 25 μm in particle size is mixed with 6% by weight of carbonyl iron powder with 5 μm in particle size.

[0062] Example 6

[0063] The difference from Example 1 is that in step (10), the raw material powder having a particle size of 25 μm in weight of 93% is mixed with the carbonyl iron powder having a particle size of 5 μm in weight of 7%.

[0064] Example 7

[0065] The difference from Example 1 is that in step (10), the raw material powder having a particle size of 25 μm in weight of 95% is mixed with the carbonyl iron powder having a particle size of 2 μm in weight of 5%.

[0066] Example 8

[0067] The difference from Example 1 is that in step (10), the raw material powder having a particle size of 25 μm in weight of 95% is mixed with the carbonyl iron powder having a particle size of 8 μm in weight of 5%.

[0068] Example 9

[0069] The difference from Example 1 is that in step (10), the raw material powder having a particle size of 25 μm in weight of 85% is mixed with the carbonyl iron powder having a particle size of 5 μm in weight of 15%.

[0070] Example 10

[0071] The difference from Example 1 is that in step (10), the raw material powder having a particle size of 25 μm in weight of 90% is mixed with the carbonyl iron powder having a particle size of 5 μm in weight of 10%.

[0072] Example 11

[0073] The difference from Example 1 is that in step (14), the magnetic powder core molded by pressing at a low pressure is subjected to secondary pressing at a pressure of 800 MPa.

[0074] Example 12

[0075] The difference from Example 1 is that in step (14), the magnetic powder core molded by pressing at a low pressure is subjected to secondary pressing at a pressure of 1200 MPa.

[0076] Comparative Example 1

[0077] The difference from Example 1 is that in step (10), the carbonyl iron powder is not mixed.

[0078] Comparative Example 2

[0079] The difference from Example 1 is that the carbonyl iron powder is not coated.

[0080] Comparative Example 3

[0081] The difference between Example 1 and Comparative Example 2 is that in step (13), the prepared powder is only pressed into a magnetic powder core at a low pressure of 200 MPa once, without secondary pressing.

[0082] Comparative Example 4

[0083] The difference between Example 1 and Comparative Example 2 is that in step (13), the prepared powder is only pressed into a magnetic powder core at a low pressure of 500 MPa once, without secondary pressing.

[0084] Performance characterization:

[0085] Density is measured by a MH-600A solid density meter from Beijing Zhide Innovative Instrument and Equipment Co., Ltd.

[0086] Permeability is calculated by measuring the inductance value of the magnetic ring, and then using the formula.

[0087] Loss is measured by Japan Iwasaki 8218B-H instrument under the condition of 1000 k100 mt.

[0088] The performance parameters of the above examples and comparative examples are shown in Table 1 below.

[0089] Table 1

[0090]

[0091]

[0092] The above is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method of producing a soft magnetic material, characterized by, The preparation method comprises: The iron alloy powder and the magnesium oxide coated carbonyl iron powder are mixed, and the mixed powder is sequentially subjected to granulation, primary pressing, secondary pressing and first annealing treatment to obtain the soft magnetic material; wherein the pressure in the primary pressing process is lower than the pressure in the secondary pressing process; The weight ratio of the iron alloy powder to the magnesium oxide coated carbonyl iron powder is (90-98):(2-10); The pressure in the primary pressing process is 200-500 MPa; and the pressure in the secondary pressing process is 800-1000 MPa; The iron alloy powder is prepared by the following method: the iron alloy raw material is sequentially subjected to second annealing treatment, first sieving treatment and insulation treatment to obtain the iron alloy powder; The insulation treatment comprises: mixing the material after the first sieving treatment, an organic solvent and phosphoric acid, so that the phosphoric acid reacts with the material after the first sieving treatment and coats the outer surface of the material and forms a phosphating layer to obtain the iron alloy powder; The iron alloy raw material is selected from one or more of iron-silicon-cadmium, iron-silicon-molybdenum, iron-silicon-aluminum, iron-nickel or cerium-iron-nitrogen; and the particle size of the material after the first sieving treatment is 20-80 μm; The magnesium oxide coated carbonyl iron powder is prepared by the following method: The iron powder is subjected to a chemical reaction under the condition of a mixed gas of hydrogen and carbon monoxide and a temperature of 300-500 ℃ to obtain carbonyl iron powder; The carbonyl iron powder is subjected to second sieving treatment to obtain a material after the second sieving treatment; The material after the second sieving treatment is mixed with a magnesium acetate aqueous solution, and then water is removed to obtain magnesium acetate coated carbonyl iron powder; The magnesium acetate coated carbonyl iron powder is subjected to a thermal decomposition reaction under the condition of an inert gas atmosphere and a temperature of 300-500 ℃ to obtain the magnesium oxide coated carbonyl iron powder; The particle size of the material after the second sieving treatment is 2-8 μm.

2. The method of producing a soft magnetic material according to claim 1, characterized by, In the first annealing treatment, the treatment temperature is 500-900 ℃, and the treatment time is 3-20 h.

3. The method of producing a soft magnetic material according to claim 1, characterized by, After the granulation, the material after the granulation is mixed with a release agent, and then the primary pressing is performed.

4. The method of producing a soft magnetic material according to claim 3, characterized by, The release agent is selected from a stearic acid release agent.

5. The method of producing a soft magnetic material according to claim 4, characterized in that, The stearic acid release agent is one or more of zinc stearate, aluminum stearate, magnesium stearate, calcium stearate or lithium stearate.

6. The method of producing a soft magnetic material according to claim 3, wherein The amount of the release agent is 0.1-2% of the weight of the material after the granulation.

7. The method of producing a soft magnetic material according to claim 1, wherein In the second annealing treatment, the treatment temperature is 500-1000 ℃, and the treatment time is 3-20 h.

8. The method of producing a soft magnetic material according to claim 1, wherein In the insulation treatment, the amount of the phosphoric acid is 0.1-6% of the weight of the material after the first sieving treatment.

9. The method of producing a soft magnetic material according to claim 1, wherein In the insulation treatment, the organic solvent is an alcohol solvent.

10. The method of producing a soft magnetic material according to claim 9, wherein The organic solvent is one or more of n-butanol, ethanol, acetone or methanol.

11. The method of producing a soft magnetic material according to claim 1, characterized by, The flow rate of the mixed gas is 5-20 L / min.

12. The method of producing a soft magnetic material according to claim 1, characterized by, The weight ratio of the material after the second sieving treatment to the magnesium acetate aqueous solution is 100:(1-5).

13. The method of producing a soft magnetic material according to claim 1, wherein The time of the thermal decomposition reaction is 20-80 min.

14. A soft magnetic material, characterized by, The soft magnetic material is prepared by the preparation method of the soft magnetic material according to any one of claims 1-13.

Images