Nanometer metal oxide insulating material coated soft magnetic composite material and preparation method thereof

Abstract

The application discloses a soft magnetic composite material coated with nano metal oxide insulating material and a preparation method thereof. The preparation method comprises the following steps: (1) putting metal soft magnetic powder and nano metal oxide insulating material into a steel bottle provided with rotating blades, the blades rotate to drive the raw materials to flow, and a core-shell type composite powder is obtained; (2) annealing the core-shell type composite powder to obtain a precursor; and (3) mixing the precursor and a lubricant, then pressing into a blank, and annealing the blank under a protective atmosphere to obtain a soft magnetic composite material. The prepared soft magnetic composite material has uniform insulating layers and high coverage, the nano metal oxide has strong bonding force with the metal soft magnetic matrix, the thickness of the coating layer is controllable, the obtained soft magnetic composite material has high magnetic permeability and lower loss, the insulating coating method has mild process conditions, simple equipment, short coating treatment time, high efficiency, low cost, and is suitable for large-scale production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic materials, in particular to a soft magnetic composite material coated with a nano-metal oxide insulating material and a preparation method thereof. BACKGROUND

[0002] The metal soft magnetic composite material is prepared by insulating material coating treatment of metal magnetic powder, and then shaping, heat treatment and other processes. It is also called metal magnetic powder core. It has high permeability, low loss and high DC bias characteristics. As the core part of reactors, transformers, converters, inductors and motor stators, it is widely used in power supplies, motors and other fields.

[0003] The metal magnetic powder used for the soft magnetic composite material includes Fe, FeSi, FeSiAl, FeNi, FeNiMo, amorphous nanocrystalline soft magnetic material, etc. The insulating materials include organic matter, inorganic matter and organic-inorganic mixture. The organic matter is easy to coat uniformly, but it is prone to decomposition and has insufficient heat resistance, thus affecting the magnetic properties of the soft magnetic composite material. The inorganic matter includes phosphate, oxide and ferrite, etc. Among them, phosphate will decompose at 500℃, so it also has low heat resistance. Ferrite is difficult to adjust the performance to the optimum because it needs to be treated in an oxidizing atmosphere, which is different from the reducing or neutral atmosphere required for the treatment of metal soft magnetic materials. Oxide is widely used at present because it has high insulation, good temperature stability and low requirements for atmosphere, etc. In particular, nano-metal oxide is widely used because it has fine particles, uniform coating, controllable thickness and good insulation, etc.

[0004] There are extensive research and application on how to insulate and coat metal magnetic powder with nano-metal oxide. Chinese invention patent 201910702030X uses epoxy resin to insulate and coat metal magnetic powder organically, and then uses silane coupling agent to modify and couple the nano-silicon oxide powder generated by hydrolysis of epoxy resin and tetraethyl orthosilicate, realizing the composite insulation of epoxy resin and silicon oxide on metal magnetic powder. Chinese invention patent 2020113331544 uses nano-SiO2, organic solvent, silicone resin and silane coupling agent coating supplement liquid to soak the FeSi, FeSiAl, FeNi and other magnetic powder cores after heat treatment, in order to improve the magnetic properties. Chinese invention patent 2023111726270 generates a first layer of SiO2 insulating layer on the surface of FeSiAl powder by using silicon source, oleic acid, acidifying agent and heating, and then adds aluminum source and alkali solution and heats to generate a second layer of Al2O3 insulating layer.

[0005] The above patent adopts a method of generating nano-oxides by reaction or directly adopting nano-oxides for coating treatment, which can realize coating effect, but the process is relatively complex, the process time is long, it is difficult to control, and the bonding strength of the coating layer and the base metal is also difficult to guarantee, which affects the magnetic property stability of the soft magnetic composite material and increases the preparation cost. SUMMARY

[0006] The purpose of the present application is to provide a soft magnetic composite material coated with nano-metal oxide insulating material and a preparation method, so as to solve the problems of the above-mentioned metal magnetic powder coating method, which is relatively complex, the process time is long, the bonding strength of the coating layer and the base metal is difficult to guarantee, and the magnetic property of the obtained soft magnetic composite material is unstable.

[0007] To achieve the above-mentioned purpose, the first aspect of the present application provides a preparation method of a soft magnetic composite material coated with nano-metal oxide insulating material, comprising the following steps:

[0008] (1) Put the metal soft magnetic powder and the nano-metal oxide insulating material into a steel bottle provided with rotating blades, the blades rotate to drive the raw materials to flow, and obtain a core-shell type composite powder;

[0009] (2) Anneal the core-shell type composite powder to obtain a precursor;

[0010] (3) Mix the precursor and a lubricant, then press into a blank, and perform annealing heat treatment on the blank in a protective atmosphere to obtain a soft magnetic composite material.

[0011] Preferably, in step (1), the metal soft magnetic powder includes one or more of FeSi, FeSiAl, FeNi, FeNiMo, FeSiB amorphous, and FeCuNbSiB nanocrystalline; and the nano-metal oxide insulating material includes one or more of SiO2, Al2O3, TiO2, MgO, kaolin, and clay.

[0012] Preferably, in step (1), the average particle size of the metal soft magnetic powder is 5 μm to 200 μm, and the average particle size of the nano-metal oxide insulating material is 2 nm to 200 nm.

[0013] Preferably, in step (1), the mass ratio of the nano-metal oxide insulating material to the metal soft magnetic powder is (0.2-5) :(99.8-95).

[0014] Preferably, in step (1), the speed of the blade rotation is 3000-8000 revolutions per minute, the linear speed generated is 20-30 m / s, and the processing time is 2-10 minutes.

[0015] Preferably, in step (2), the annealing temperature is 200-600℃, the annealing time is 20-60min, and the annealing atmosphere is argon or nitrogen.

[0016] Preferably, in step (3), the lubricant comprises zinc stearate or lithium stearate, or both, and the amount of the lubricant added is 0.2wt.%-1.2wt.% of the precursor.

[0017] The precursor further comprises a silane coupling agent and an organic resin, the amount of the silane coupling agent added is 0-0.5wt.% of the precursor, and the organic resin is one or both of silicone resin and epoxy resin, and the amount of the organic resin added is 0-1.0wt.% of the precursor.

[0018] Preferably, in step (3), the amount of the silane coupling agent added is 0.03-0.5wt.% of the precursor, and the amount of the organic resin added is 0.06-1.0wt.% of the precursor.

[0019] Preferably, in step (3), the pressure for the pressing is 800-2200MPa, and the pressure holding time is 0-5s.

[0020] Preferably, in step (3), the annealing temperature is 400-800℃, the annealing time is 30-120min, and the annealing atmosphere is one or both of argon and nitrogen.

[0021] The second aspect of the present application provides a soft magnetic composite material coated with nano metal oxide insulating material, which is prepared by the above method.

[0022] Preferably, the nano metal oxide insulating material in the soft magnetic composite material is uniformly adhered to the surface of the metal soft magnetic powder, forming a core-shell type composite material in which the metal soft magnetic powder is coated with the nano metal oxide insulating material.

[0023] Therefore, the soft magnetic composite material coated with nano metal oxide insulating material and the preparation method thereof have the following beneficial effects:

[0024] (1) The nano metal oxide insulating material in the soft magnetic composite material prepared by the present application is uniformly distributed on the surface of the metal soft magnetic powder, has high coverage, has strong bonding force between the nano metal oxide insulating material and the metal soft magnetic powder, and has controllable coating thickness, so that the prepared soft magnetic composite material has high magnetic permeability and lower loss.

[0025] (2) The insulating coating method of the present application has mild process conditions, simple equipment, short coating time, high efficiency, and low cost, and is suitable for large-scale production.

[0026] The technical solutions of the present application will be further described in detail below with reference to the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 SEM image of FeSiAl raw powder particles by gas atomization;

[0028] Figure 2 EDS image of FeSiAl raw powder particles by gas atomization;

[0029] Figure 3 SEM image of FeSiAl composite powder particles coated with a nano-SiO2 insulating layer in Example 1;

[0030] Figure 4 EDS image of FeSiAl composite powder particles coated with a nano-SiO2 insulating layer in Example 1. DETAILED DESCRIPTION

[0031] The present application will be further described below. It should be noted that the present embodiment is based on the technical solution of the present application, and gives a detailed implementation and specific operation process, but the present application is not limited to the present embodiment.

[0032] Example 1

[0033] The preparation method of the soft magnetic composite material coated with a nano-metal oxide insulating material comprises the following steps:

[0034] FeSiAl powder is prepared by atomization method, and SEM morphology and EDS spectrum of the powder are shown in Figure 1 and Figure 2 FeSiAl powder of 500 g with a particle size of 30 μm is slowly put into a stainless steel cylinder provided with a fast rotating blade, then 0.5 wt.% (2.5 g) of SiO2 powder with a particle size of 20 nm is also put into the cylinder, and the rotating blade is opened, the rotating speed is adjusted to 5000 r / min, and FeSiAl@SiO2 coated powder is obtained after mixing for 5 min, and SEM image and EDS spectrum are shown in Figure 3 and Figure 4 The stainless steel cylinder provided with a fast rotating blade used in the present application is a device disclosed in the prior art, and the device name is high-efficiency fusion coating machine, the manufacturer is Wuxi Tai Xian Powder Technology Co., Ltd., and the equipment model is VSH-0.3.

[0035] The process of preparing FeSiAl powder by atomization method in the present embodiment is as follows:

[0036] Fe, Si and Al elements are put into a vacuum induction melting furnace according to the composition of Fe-9.6Si-5.4Al, and then melted at 1500℃, and then sprayed and powdered by nitrogen.

[0037] Table 1. Element content of the gas atomized FeSiAl raw powder particles

[0038]

[0039] Table 2. Element content of the FeSiAl@SiO2 coated powder

[0040]

[0041] Subsequently, the FeSiAl@SiO2 coated powder was placed in a tube furnace and treated at 400℃ for 30min under argon, then 0.4wt.% KH550 was added to the annealed FeSiAl@SiO2 coated powder and stirred uniformly, and then 0.8wt.% silicone resin was added and stirred uniformly to obtain the final coated powder.

[0042] The silicone resin is a high-temperature-resistant silicone resin produced by Hubei Xinsihai Chemical Co., Ltd., and the model number is 9603.

[0043] 0.5wt.% zinc stearate lubricant was added to the coated powder and mixed uniformly, and then the mixture was pressed into a ring-shaped compact (outer diameter 27mm*inner diameter 15mm*height 11mm) under a pressure of 2000MPa; the ring-shaped compact was heat treated under an argon atmosphere for 50min at a heat treatment temperature of 700℃; then the furnace was cooled to room temperature while maintaining ventilation (to prevent the sample from being oxidized) during the cooling process, and a FeSiAl@SiO2 soft magnetic composite material was obtained.

[0044] Example 2

[0045] The method for preparing a soft magnetic composite material coated with a nano metal oxide insulating material comprises the following steps:

[0046] FeSi powder was prepared by atomization method, 500g of FeSi powder with a particle size of 32μm was slowly placed in a stainless steel cylinder equipped with a fast rotating blade, then 0.7wt.% (3.5g) of SiO2 powder with a particle size of 10nm was also placed in the cylinder, and the rotating blade was turned on, the rotating speed was adjusted to 6000r / min, and after mixing for 4min, FeSi@SiO2 coated powder was obtained.

[0047] In this example, the process for preparing FeSiAl powder by atomization method is as follows:

[0048] Fe and Si elements were placed in a vacuum induction melting furnace according to the Fe-5.5Si composition, and then melted at 1500℃, and then nitrogen was used for spray powdering.

[0049] Then the FeSi@SiO2 coated powder was placed in a tube furnace and treated at 450℃ for 20min under argon. Then 0.5wt.% KH550 was added to the annealed FeSi@SiO2 coated powder and stirred uniformly, and then 1.0wt.% silicone resin was added and stirred uniformly to obtain the final coated powder.

[0050] 0.4wt.% zinc stearate lubricant was added to the coated composite powder and mixed uniformly, and then pressed into a ring-shaped compact (outer diameter 27mm*inner diameter 15mm*height 11mm) under a pressure of 1900MPa. The ring-shaped compact was heat treated under an argon atmosphere for 45min, and the heat treatment temperature was 680℃. Then the furnace was cooled to room temperature (ventilation was maintained throughout the process of cooling to room temperature (to prevent the sample from being oxidized)), and a FeSiAl@Al2O3 soft magnetic composite material was obtained.

[0051] Example 3

[0052] A method for preparing a soft magnetic composite material coated with a nano-metal oxide insulating material, comprising the following steps:

[0053] FeSiAl powder was prepared by an atomization method. 500g of FeSiAl powder with a particle size of 18μm was slowly placed in a stainless steel bottle equipped with rapidly rotating blades, and then 0.8wt.% (4.0g) of Al2O3 powder with a particle size of 60nm was also placed in the steel bottle, and the rotating blades were turned on. The speed was adjusted to 5600r / min, and the mixture was mixed for 6min to obtain FeSiAl@Al2O3 coated powder. The process of preparing FeSiAl powder by atomization was the same as that of Example 1.

[0054] Then the FeSiAl@Al2O3 coated powder was placed in a tube furnace and treated at 480℃ for 35min under argon. Then 0.35wt.% KH550 was added to the annealed FeSiAl@Al2O3 coated powder and stirred uniformly, and then 0.7wt.% silicone resin was added and stirred uniformly to obtain the final coated powder.

[0055] 0.4wt.% zinc stearate lubricant was added to the coated composite powder and mixed uniformly, and then pressed into a ring-shaped compact (outer diameter 27mm*inner diameter 15mm*height 11mm) under a pressure of 1900MPa. The ring-shaped compact was heat treated under an argon atmosphere for 45min, and the heat treatment temperature was 680℃. Then the furnace was cooled to room temperature (ventilation was maintained throughout the process of cooling to room temperature (to prevent the sample from being oxidized)), and a FeSiAl@Al2O3 soft magnetic composite material was obtained.

[0056] Example 4

[0057] A method for preparing a soft magnetic composite material coated with a nano-metal oxide insulating material, comprising the following steps:

[0058] FeSi powder was prepared by atomization method. 500 g of FeSi powder with a particle size of 52 μm was slowly placed in a stainless steel cylinder with a fast rotating blade, then 1.0 wt.% (5.0 g) of Al2O3 powder with a particle size of 30 nm was also placed in the cylinder, and the rotating blade was turned on with a speed of 6500 r / min. After mixing for 4.5 min, FeSi@Al2O3 coated powder was obtained. The preparation method of FeSi powder was the same as that of Example 2.

[0059] Subsequently, the FeSi@Al2O3 coated powder was placed in a tube furnace and treated at 500°C for 25 min under argon. Then, 0.45 wt.% of KH550 was added to the annealed FeSi@Al2O3 coated powder and stirred uniformly, and then 0.9 wt.% of silicone resin was added and stirred uniformly to obtain the final coated powder.

[0060] 0.5 wt.% of zinc stearate lubricant was added to the coated composite powder and mixed uniformly, and then the mixture was pressed into a ring-shaped compact (outer diameter 27 mm * inner diameter 15 mm * height 11 mm) under a pressure of 1900 MPa. The ring-shaped compact was heat treated under an argon atmosphere for 30 min at a heat treatment temperature of 740°C, and then cooled to room temperature in the furnace while maintaining ventilation (to prevent the sample from being oxidized) during the cooling process to obtain a FeSi@Al2O3 soft magnetic composite material.

[0061] Comparative Example 1

[0062] A method for preparing a soft magnetic composite material coated with a nano-metal oxide insulating material, comprising the following steps:

[0063] FeSiAl powder was prepared by atomization method. 500 g of FeSiAl powder with a particle size of 30 μm was slowly placed in a mixer, then 0.5 wt.% (2.5 g) of SiO2 powder with a particle size of 20 nm was also placed in the mixer, a small amount of steel balls was added, the ball-to-material weight ratio was 1:1, the mixer speed was 150 r / min, and after mixing for 360 min, FeSiAl@SiO2 coated powder was obtained. The preparation method of FeSiAl powder was the same as that of Example 1.

[0064] Subsequently, the FeSiAl@SiO2 coated powder was placed in a tube furnace and treated at 400°C for 30 min under argon. Then, 0.4 wt.% of KH550 was added to the annealed FeSiAl@SiO2 coated powder and stirred uniformly, and then 0.8 wt.% of silicone resin was added and stirred uniformly to obtain the final coated powder.

[0065] 0.5wt.% zinc stearate lubricant was added to the coated composite powder and mixed evenly, and then pressed into a ring-shaped compact (outer diameter 27mm*inner diameter 15mm*height 11mm) under a pressure of 2000MPa; the ring-shaped compact was heat treated under an Ar atmosphere for 50min, and the heat treatment temperature was 700°C; then furnace cooling was performed to room temperature (ventilation was maintained throughout the furnace cooling process (to prevent the sample from being oxidized)), to obtain a FeSiAl@SiO2 soft magnetic composite material.

[0066] Comparative Example 2

[0067] A method for preparing a soft magnetic composite material coated with a nano-metal oxide insulating material, comprising the following steps:

[0068] FeSi powder was prepared by an atomization method, 500g of FeSi powder with a particle size of 32μm was slowly placed into a mixer, then 1.0wt.% (5.0g) of Al2O3 powder with a particle size of 10nm was also placed into the mixer, a small amount of steel balls were added, the ball-to-material weight ratio was 1:1, the mixer rotation speed was 120r / min, and after mixing for 390min, FeSi@Al2O3 coated powder was obtained. Subsequently, the FeSi@Al2O3 coated powder was placed in a tube furnace and treated at 500°C for 25min under argon. Then 0.45wt.% of KH550 was added to the annealed FeSi@Al2O3 coated powder and stirred evenly, and then 0.9wt.% of silicone resin was added and stirred evenly, to obtain the final coated powder.

[0069] 0.5wt.% zinc stearate lubricant was added to the coated composite powder and mixed evenly, and then pressed into a ring-shaped compact (outer diameter 27mm*inner diameter 15mm*height 11mm) under a pressure of 1900MPa; the ring-shaped compact was heat treated under an Ar atmosphere for 30min, and the heat treatment temperature was 740°C; then furnace cooling was performed to room temperature (ventilation was maintained throughout the furnace cooling process (to prevent the sample from being oxidized)), to obtain a FeSi@Al2O3 soft magnetic composite material.

[0070] Comparative Example 3

[0071] A method for preparing a soft magnetic composite material coated with a nano-metal oxide insulating material, comprising the following steps:

[0072] FeSiAl powder was prepared by atomization method (the preparation method and embodiment 1 were the same), 500 g of FeSiAl powder with a particle size of 18 μm was slowly put into a mixer, then 3.0 wt.% (15.0 g) of aluminum sol was also put into the mixer, a small amount of steel balls was put in, the ball-to-material weight ratio was 1:1, the mixer rotation speed was 120 r / min, and the aluminum sol coated FeSiAl powder was obtained after mixing for 280 min. Subsequently, the aluminum sol coated FeSiAl powder was placed in a tube furnace and treated at 800 ℃ for 30 min under argon. During the heat treatment process, the aluminum sol was first converted into aluminum gel, and finally Al2O3 was uniformly coated on the surface of FeSiAl. Then 0.5 wt.% of KH550 was added to the heat-treated FeSiAl@Al2O3 coated powder and stirred uniformly, and then 1.0 wt.% of silicone resin was added and stirred uniformly to obtain the final coated powder.

[0073] 0.5 wt.% of zinc stearate lubricant was added to the coated composite powder and mixed uniformly, and the coated composite powder was pressed into a ring-shaped compact (outer diameter 27 mm*inner diameter 15 mm*height 11 mm) under a pressure of 2000 MPa; the ring-shaped compact was heat treated at 680 ℃ for 40 min under an argon atmosphere; then the furnace was cooled to room temperature (the furnace was kept ventilated during the cooling process to prevent the sample from being oxidized), and a FeSiAl@Al2O3 soft magnetic composite material was obtained.

[0074] Performance test

[0075] The FeSiAl and FeSi soft magnetic composite material samples prepared in embodiments 1 to 4, the FeSiAl soft magnetic composite material prepared in comparative example 1, the FeSi soft magnetic composite material sample prepared in comparative example 2, and the material sample prepared in comparative example 3 were respectively subjected to magnetic permeability and magnetic loss tests by using a SY-8218 alternating current B-H analyzer, and the performance of the obtained samples is shown in Table 3 (B max = 50 mT).

[0076] Table 3 Performance of the composite materials prepared in embodiments 1 to 4 and comparative examples 1 to 2

[0077]

[0078]

[0079] From Table 3 above, it can be seen that:

[0080] Compared with the existing FeSiAl soft magnetic composite material (prepared in Comparative Example 1), the FeSiAl soft magnetic composite material sample prepared in Example 1 has better permeability and frequency characteristics, the permeability has better stability with the increase of frequency, has smaller magnetic loss at high frequency, and has equivalent DC bias, and the process cycle used is shorter / higher in efficiency.

[0081] Compared with the existing FeSi soft magnetic composite material (prepared in Comparative Example 2), the FeSi soft magnetic composite material sample prepared in Example 2 has better permeability and frequency characteristics, the permeability has better stability with the increase of frequency, has smaller magnetic loss at high frequency, and has equivalent DC bias, and the process cycle used is shorter / higher in efficiency.

[0082] Compared with the existing FeSiAl soft magnetic composite material (prepared in Comparative Example 3), the FeSiAl soft magnetic composite material sample prepared in Example 3 has better permeability and frequency characteristics, the permeability has better stability with the increase of frequency, has smaller magnetic loss at high frequency, and has equivalent DC bias, and the process cycle used is shorter / higher in efficiency.

[0083] Compared with the existing FeSi soft magnetic composite material (prepared in Comparative Example 2), the FeSi soft magnetic composite material sample prepared in Example 4 has better permeability and frequency characteristics, the permeability has better stability with the increase of frequency, has smaller magnetic loss at high frequency, and has equivalent DC bias, and the process cycle used is shorter / higher in efficiency.

[0084] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application rather than limit it, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that: it can still modify or equivalent replace the technical solutions of the present application, and these modifications or equivalent replacements also cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for producing a soft magnetic composite material coated with a nanometal oxide insulating material, characterized by: The method comprises the following steps: (1) putting metal soft magnetic powder and nano metal oxide insulating material into a steel bottle with rotating blades, the blades rotating to drive the raw materials to flow, to obtain core-shell composite powder; (2) annealing the core-shell composite powder to obtain a precursor; (3) mixing the precursor and a lubricant, then pressing into a blank, and annealing the blank under a protective atmosphere to obtain a soft magnetic composite material; In step (1), the metal soft magnetic powder comprises one or more of FeSi, FeSiAl, FeNi, FeNiMo, FeSiB amorphous, and FeCuNbSiB nanocrystalline; the nano metal oxide insulating material comprises one or more of SiO2, Al2O3, TiO2, MgO, kaolin, and clay; and the mass ratio of the nano metal oxide insulating material to the metal soft magnetic powder is (0.2-5):(99.8-95).

2. The method for preparing a soft magnetic composite material coated with nano-metal oxide insulating material according to claim 1, characterized in that: In step (1), the average particle size of the metal soft magnetic powder is 5-200 μm, and the average particle size of the nano metal oxide insulating material is 2-200 nm.

3. The method for preparing a soft magnetic composite material coated with nano-metal oxide insulating material according to claim 1, characterized in that: In step (1), the rotating speed of the blades is 3000-8000 rpm, the linear speed generated is 20-30 m / s, and the processing time is 2-10 min.

4. The method for preparing a soft magnetic composite material coated with nano-metal oxide insulating material according to claim 1, characterized in that: In step (2), the annealing temperature is 200-600 ℃, the time is 20-60 min, and the atmosphere is argon or nitrogen.

5. The method for preparing a soft magnetic composite material coated with nano-metal oxide insulating material according to claim 1, characterized in that: In step (3), the lubricant comprises one or both of zinc stearate and lithium stearate, the amount of the lubricant added is 0.2-1.2 wt.% of the precursor; silane coupling agent and organic resin are further added to the precursor, the amount of the silane coupling agent added is 0-0.5 wt.% of the precursor, the organic resin is one or both of silicone resin and epoxy resin, and the amount of the organic resin added is 0-1.0 wt.% of the precursor.

6. The method for preparing a soft magnetic composite material coated with nano-metal oxide insulating material according to claim 1, characterized in that: In step (3), the pressing pressure is 800-2200 MPa, and the pressure holding time is 0-5 s.

7. The method for preparing a soft magnetic composite material coated with nano-metal oxide insulating material according to claim 1, characterized in that: In step (3), the annealing temperature is 400-800 ℃, the holding time is 30-120 min, and the protective atmosphere is one or a mixture of both of argon and nitrogen.

8. Soft magnetic composite material coated with nanometal oxide insulating material, characterized in that: The soft magnetic composite material is prepared by the method of any one of claims 1-7.

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