Composite soft magnetic material and preparation method thereof

Abstract

The invention relates to the technical field of magnetic materials, in particular to a composite soft magnetic material and a preparation method thereof.The composite soft magnetic material comprises Fe-Mn-Al-P-Co soft magnetic powder, the Fe-Mn-Al-P-Co soft magnetic powder is flattened, then the flattened soft magnetic powder is evenly dispersed in modified epoxy resin, and the composite soft magnetic material is obtained. And then pressing and curing to prepare the composite soft magnetic material. The composition elements of the soft material are optimized, the conflict between the mechanical performance and the soft magnetic performance is avoided through unique structural design and mechanism optimization, flattening treatment is carried out, and the soft material is dispersed in epoxy resin so as to improve the magnetic performance of the soft material in a high-frequency magnetic field; through combination of epoxy resin modification and magnetic field induction, the magnetic material can be uniformly dispersed in the modified epoxy resin, and the cured composite soft magnetic material has excellent mechanical properties and soft magnetic properties.

Description

Technical Field

[0001] The present application relates to the technical field of magnetic materials, and particularly relates to a composite soft magnetic material and a preparation method thereof. Background Art

[0002] Soft Magnetic Composites (SMCs), also known as metal magnetic powder core materials, are a new type of composite material prepared by surface coating ferromagnetic powder particles with an insulating medium. This type of material greatly broadens the effective operating frequency of traditional metal soft magnetic materials. By forming a high resistance on the surface of the soft magnetic powder through insulation coating, the bulk resistivity of the soft magnetic composite material is increased, thereby improving the magnetic permeability of the material at high frequencies, reducing eddy current losses, and improving the DC bias performance to meet the requirements for the service of metal soft magnetic composites at high frequencies. Those applied industrially include iron powder cores, iron-silicon powder cores, iron-silicon-aluminum powder cores, permalloy powder cores, etc. In recent years, the development of industries such as wind power generation, photovoltaic power generation, new energy vehicles, and 5G communication has led to a rapid increase in the demand for high-performance soft magnetic composite materials.

[0003] The key preparation technology of soft magnetic composite materials is the insulation coating treatment of powders. This technology is the key for materials to obtain high magnetic permeability and low losses, and is an important factor determining the operating frequency of materials. Currently, the main insulation coatings include organic coatings and inorganic coatings. Among them, organic coating agents include epoxy resin, silicone resin, acrylic acid, phenolic resin, polyester, epoxy resin-polyester, etc. However, due to their intolerance to high temperatures, organic insulating resins can only be heat-treated at relatively low temperatures, and it is difficult to eliminate the residual stress generated during the pressing process, which is not conducive to the improvement of magnetic properties. Moreover, during the coating process, it is difficult for soft magnetic composite materials to be evenly dispersed in the organic coating agent, and the mechanical properties of the soft magnetic materials cannot be guaranteed, thus limiting their practical applications. Summary of the Invention

[0004] The present application provides a composite soft magnetic material and a preparation method thereof to solve the related technical problems existing in the organic coating process of soft magnetic composite materials in the prior art.

[0005] In a first aspect, the present application provides a composite soft magnetic material, which includes Fe-Mn-Al-P-Co soft magnetic powder. After flattening the Fe-Mn-Al-P-Co soft magnetic powder, the flattened soft magnetic powder is then evenly dispersed in modified epoxy resin, and then the composite soft magnetic material is prepared through pressing and curing.

[0006] Optionally, in the soft magnetic material Fe-Mn-Al-P-Co, the mass percentage of iron is 41.3, the mass percentage of manganese is 24, the mass percentage of aluminum is 20, the mass percentage of phosphorus is 12.4, and the mass percentage of cobalt is 2.3.

[0007] Optionally, the flattening treatment is to place the Fe-Mn-Al-P-Co soft magnetic powder in a ball milling device and add an appropriate amount of ethylene glycol for ball milling.

[0008] Optionally, during the ball milling process, the ball milling beads are zirconium balls with a weight of 1.2 kg and a diameter of 1.3 - 1.6 mm, the ball milling speed is 2500 rpm, and the ball milling time is 6 - 7 h.

[0009] Optionally, the preparation method of the modified epoxy resin includes the following steps: S31: Add benzoxazine to the epoxy resin (E-51), and then stir at a speed of 1000 r / min for 20 - 30 min under the condition of 55°C; S32: Continuously add 4,4 ， -diaminodiphenylmethane to the reaction system and continue stirring for 15 - 20 min; S33: Put the stirred modified epoxy resin into a vacuum-pressure impregnation furnace to evacuate for 20 - 30 min, and the vacuum degree is 1 mPa.

[0010] Optionally, by mass fraction, the addition amounts of the epoxy resin (E-51) and benzoxazine are 10 - 13:2 - 5.

[0011] Optionally, the soft magnetic material is subjected to magnetic field orientation induction treatment before curing, and the magnetic field strength is 1.5 - 2 T.

[0012] On the other hand, the present application provides a preparation method of a composite soft magnetic material, including the following steps: S1: After flattening the Fe-Mn-Al-P-Co soft magnetic powder, flaky soft magnetic powder is obtained; S2: Modify the epoxy resin with benzoxazine and 4,4 ， -diaminodiphenylmethane to obtain a modified epoxy resin; S4: Uniformly disperse the flaky soft magnetic powder in the modified epoxy resin, incorporate p-phenylenediamine, and then perform pressing, and cure the pressed soft magnetic material to obtain a composite soft magnetic material.

[0013] Optionally, by weight, the addition amounts of the soft magnetic powder and the modified epoxy resin are 100:1.3 - 1.8.

[0014] Optionally, the curing temperature is 150 - 200°C.

[0015] The above technical solutions provided by the embodiments of the present application have the following advantages compared with the prior art: A composite soft magnetic material and its preparation method provided by an embodiment of the present application. Almost all existing soft magnetic materials have a major defect - insufficient mechanical properties. On the one hand, it is very difficult to process them into complex and special shapes, unable to meet the higher-level industrial demands. On the other hand, the service life is short, and the defective products and scrap rates are very high, resulting in a large amount of waste and bringing great losses to the production process. The key to the problem is that most methods to improve the mechanical properties of materials will significantly reduce the soft magnetic properties of the materials. Through unique structural design and mechanism optimization, the present application optimizes the constituent elements of the soft magnetic material, enabling the mechanical properties of the soft magnetic material to be optimized while avoiding the reduction of soft magnetic properties. At the same time, it is flattened to make it into a flaky soft magnetic material with a particle size of 15 - 25 um to improve its magnetic induction intensity, high magnetic permeability and other characteristics. However, its magnetic performance is not prominent in high-frequency applications. On this basis, in order to further improve the magnetic performance of the soft magnetic material in high-frequency applications, the present application disperses it in epoxy resin to enhance its magnetic performance in high-frequency applications. However, during the dispersion process, due to the influence of the physical and chemical properties of epoxy resin itself, the soft magnetic material cannot be evenly dispersed in epoxy resin. The present application induces it through the action of a magnetic field to enable it to be arranged orderly parallel to the magnetic field direction. At the same time, combined with the modification treatment of epoxy resin, it can be further evenly dispersed in epoxy resin, and after the modified epoxy resin is cured, there will be no more voids inside, and the thermal conductivity will not be greatly reduced, ensuring that the composite soft magnetic material has excellent soft magnetic properties and mechanical properties. Detailed implementation mode

[0016] In an embodiment of the present application, a composite soft magnetic material includes Fe-Mn-Al-P-Co soft magnetic powder. After flattening the Fe-Mn-Al-P-Co soft magnetic powder, the flattened soft magnetic powder is then evenly dispersed in modified epoxy resin, and then the composite soft magnetic material is prepared through pressing and curing.

[0017] In the present application, through unique structural design and mechanism optimization, the constituent elements of the soft magnetic material are optimized to improve its mechanical properties while avoiding the decline of its soft magnetic properties. Combined with flattening treatment, its soft magnetic properties are further improved. Subsequently, it is dispersed in the modified resin to further enhance its soft magnetic properties. The epoxy resin is modified to avoid uneven dispersion during the dispersion process and the decline of the mechanical properties and soft magnetic properties of the soft magnetic material after curing, thereby obtaining a composite soft magnetic material with excellent soft magnetic properties, mechanical properties and mechanical properties suitable for high-frequency magnetic fields.

[0018] As an alternative embodiment, the mass percentage of iron in the soft magnetic material Fe-Mn-Al-P-Co is 41.3, the mass percentage of manganese is 24, the mass percentage of aluminum is 20, the mass percentage of phosphorus is 12.4, and the mass percentage of cobalt is 2.3.

[0019] In this application, the elemental composition of the soft magnetic material is further defined to further avoid the conflict between soft magnetic properties and mechanical properties and improve the soft magnetic properties and mechanical properties of the soft magnetic material.

[0020] As an alternative embodiment, the flattening treatment is to place the Fe-Mn-Al-P-Co soft magnetic powder in a ball milling device and add an appropriate amount of ethylene glycol for ball milling.

[0021] In this application, the medium for the flattening treatment is optimized, and ethylene glycol is selected as the medium, so that the soft magnetic material of this application can be efficiently flattened, and the phenomenon of agglomeration of the sheet-shaped soft magnetic material obtained during this process can be avoided, affecting subsequent dispersion operations.

[0022] As an alternative embodiment, during the ball milling process, the ball milling beads are zirconium balls with a weight of 1.2 kg and a diameter of 1.3 - 1.6 mm, the ball milling speed is 2500 rpm, and the ball milling time is 6 - 7 h.

[0023] In this application, the material, weight, ball milling conditions, and time of the medium (ball milling beads) for the flattening treatment are further optimized, so that the soft magnetic material can be efficiently flattened, and the phenomenon of agglomeration is further avoided.

[0024] As an alternative embodiment, the preparation method of the modified epoxy resin includes the following steps: S31: Add benzoxazine to epoxy resin (E-51), and then stir at a speed of 1000 r / min for 20 - 30 min under the condition of 55°C; S32: Continue to add 4,4 ， -diaminodiphenylmethane to the reaction system and continue stirring for 15 - 20 min; S33: Put the stirred modified epoxy resin into a vacuum-pressure impregnation furnace to evacuate for 20 - 30 min, and the vacuum degree is 1 mPa.

[0025] In this application, the epoxy resin (E51) is modified by benzoxazine, effectively improving the heat resistance of the epoxy resin. During the heating process, the release of small molecules is avoided, making the resin structure compact and without the occurrence of voids; at the same time, in combination with 4,4 ，The function of 4,4'-diaminodiphenylmethane is to improve the toughness of epoxy resin, repair the cracks generated in epoxy resin during the heating process, further improve the soft magnetic properties of the soft magnetic material. At the same time, the modified epoxy resin facilitates the uniform dispersion of the soft magnetic material therein, improving the mechanical properties of the soft magnetic material.

[0026] As an optional embodiment, by mass fraction, the addition amounts of the epoxy resin (E-51), 4,4'-diaminodiphenylmethane and benzoxazine are 10-13:4-7:2-5.

[0027] In this application, the ratio of the epoxy resin, 4,4'-diaminodiphenylmethane and benzoxazine is further optimized to improve the physical and chemical properties of the modified epoxy resin, so that its structure remains tight after heating, avoiding the generation of voids and cracks, and ensuring the relevant properties of the composite soft magnetic material.

[0028] As an optional embodiment, before curing, the soft magnetic material is subjected to magnetic field orientation induction treatment, and the magnetic field strength is 1.5-2 T.

[0029] In this application, through the magnetic field induction effect, the composite soft magnetic material can be uniformly and orderly dispersed in the modified epoxy resin, and the orderly arrangement better avoids the generation of cracks in the modified epoxy resin after heating, further improving the relevant properties of the composite soft magnetic material.

[0030] On the other hand, this application provides a preparation method of a composite soft magnetic material, including the following steps: S1. After flattening the Fe-Mn-Al-P-Co soft magnetic powder, sheet-like soft magnetic powder is obtained; S2. Modify the epoxy resin with benzoxazine and 4,4 ， '-diaminodiphenylmethane to obtain a modified epoxy resin; S3. Uniformly disperse the sheet-like soft magnetic powder in the modified epoxy resin, incorporate p-phenylenediamine, then press, and cure the pressed soft magnetic material to obtain a composite soft magnetic material.

[0031] In this application, by flattening the soft magnetic powder with optimized composition elements and combining the modification treatment of epoxy resin, strictly controlling each process link in the preparation process to improve the soft magnetic properties and mechanical properties of the soft magnetic material, etc.

[0032] As an optional embodiment, by weight, the addition amounts of the soft magnetic powder and the modified epoxy resin are 100:1.3-1.8.

[0033] In this application, the addition amounts of the soft magnetic powder and the modified epoxy resin are defined to further improve the soft magnetic properties of the composite soft magnetic material.

[0034] As an optional embodiment, the curing temperature is 150 - 200 °C.

[0035] In this application, the curing temperature is defined to ensure that no defects such as cracks and voids will appear on the surface of the cured composite soft magnetic material, thus ensuring the relevant properties of the soft magnetic material.

[0036] Example 1 A preparation method of a composite soft magnetic material, comprising the following steps: S1. Place the Fe-Mn-Al-P-Co soft magnetic powder in a ball milling device, and add an appropriate amount of ethylene glycol for ball milling to obtain flaky soft magnetic powder; during the ball milling process, the ball milling beads are zirconium balls with a weight of 1.2 kg and a diameter of 1.3 mm, the ball milling speed is 2500 rpm, and the ball milling time is 6 h; in the soft magnetic material Fe-Mn-Al-P-Co, the mass percentage of iron is 41.3, the mass percentage of manganese is 24, the mass percentage of aluminum is 20, the mass percentage of phosphorus is 12.4, and the mass percentage of cobalt is 2.3; S2. Preparation of modified epoxy resin. By mass fraction, the addition amounts of epoxy resin (E-51), 4,4'-diaminodiphenylmethane, and benzoxazine are 13:4:2; S21. Add benzoxazine to epoxy resin (E-51), and then stir at a speed of 1000 r / min for 20 min at 55 °C; S22. Continue to add 4,4 ， '-diaminodiphenylmethane to the reaction system and continue stirring for 15 min; S23. Put the stirred epoxy resin into a vacuum-pressure impregnation furnace to evacuate for 20 min to obtain modified epoxy resin, and the vacuum degree is 1 mPa; S3. Uniformly disperse the modified soft magnetic powder in the modified epoxy resin, incorporate p-phenylenediamine, and the weight ratio of the modified epoxy resin to p-phenylenediamine is 6:1, and then press to obtain a composite soft magnetic material layer; S4. Place the composite soft magnetic material layer in a magnetic field with a magnetic field strength of 1.5 T for magnetic field orientation induction to obtain a modified composite soft magnetic material layer; S5. Cure the modified composite soft magnetic material layer at 150 °C to obtain a composite soft magnetic material; by weight, the addition amounts of the soft magnetic powder and the modified epoxy resin are 100:1.3.

[0037] Example 2 A preparation method of a composite soft magnetic material, comprising the following steps: S1. Place the Fe-Mn-Al-P-Co soft magnetic powder in a ball milling device, and add an appropriate amount of ethylene glycol for ball milling to obtain flaky soft magnetic powder; during the ball milling process, the ball milling beads are zirconium balls with a weight of 1.2 kg and a diameter of 1.4 mm, the ball milling speed is 2500 rpm, and the ball milling time is 6.5 h; in the soft magnetic material Fe-Mn-Al-P-Co, the mass percentage of iron is 41.3, the mass percentage of manganese is 24, the mass percentage of aluminum is 20, the mass percentage of phosphorus is 12.4, and the mass percentage of cobalt is 2.3; S2. Preparation of modified epoxy resin. By mass fraction, the addition amounts of epoxy resin (E-51), 4,4'-diaminodiphenylmethane and benzoxazine are 11:5:2; S21. Add benzoxazine to epoxy resin (E-51), and then stir at a speed of 1000 r / min for 23 min under the condition of 55 °C; S22. Continuously add 4,4 ， -diaminodiphenylmethane to the reaction system and continue stirring for 17 min; S23. Put the stirred epoxy resin into a vacuum-pressure impregnation furnace to evacuate for 24 min to obtain modified epoxy resin, and the vacuum degree is 1 mPa; S3. Uniformly disperse the modified soft magnetic powder in the modified epoxy resin, and incorporate p-phenylenediamine. The weight ratio of the modified epoxy resin to the p-phenylenediamine is 6:1, and then press to obtain a composite soft magnetic material layer; S4. Place the composite soft magnetic material layer in a magnetic field with a magnetic field strength of 1.7 T for magnetic field orientation induction to obtain a modified composite soft magnetic material layer; S5. Cure the modified composite soft magnetic material layer at 165 °C to obtain a composite soft magnetic material; by weight, the addition amounts of the soft magnetic powder and the modified epoxy resin are 100:1.5.

[0038] Example 3 A preparation method of a composite soft magnetic material, comprising the following steps: S1. Place the Fe-Mn-Al-P-Co soft magnetic powder in a ball milling device, and add an appropriate amount of ethylene glycol for ball milling to obtain flaky soft magnetic powder; during the ball milling process, the ball milling beads are zirconium balls with a weight of 1.2 kg and a diameter of 1.4 mm, the ball milling speed is 2500 rpm, and the ball milling time is 7 h; in the soft magnetic material Fe-Mn-Al-P-Co, the mass percentage of iron is 41.3, the mass percentage of manganese is 24, the mass percentage of aluminum is 20, the mass percentage of phosphorus is 12.4, and the mass percentage of cobalt is 2.3; S2. Preparation of modified epoxy resin. By mass fraction, the addition amounts of epoxy resin (E-51), 4,4'-diaminodiphenylmethane and benzoxazine are 12:6:5. S21. Add benzoxazine to epoxy resin (E-51), and then stir at a speed of 1000 r / min for 28 min under the condition of 55 °C. S22. Continue to add 4,4 ， -diaminodiphenylmethane to the reaction system and continue stirring for 20 min. S23. Put the stirred epoxy resin into a vacuum-pressure impregnation furnace to evacuate for 25 min to obtain modified epoxy resin, and the vacuum degree is 1 mPa. S3. Uniformly disperse the modified soft magnetic powder in the modified epoxy resin, and incorporate p-phenylenediamine. The weight ratio of the modified epoxy resin to p-phenylenediamine is 6:1, and then press to obtain a composite soft magnetic material layer. S4. Place the composite soft magnetic material layer in a magnetic field with a magnetic field strength of 1.8 T for magnetic field orientation induction to obtain a modified composite soft magnetic material layer. S5. Cure the modified composite soft magnetic material layer at 180 °C to obtain a composite soft magnetic material. By weight, the addition amounts of the soft magnetic powder and the modified epoxy resin are 100:1.7.

[0039] Example 4 A preparation method of a composite soft magnetic material, comprising the following steps: S1. Place the Fe-Mn-Al-P-Co soft magnetic powder in a ball milling device, and add an appropriate amount of ethylene glycol for ball milling to obtain flaky soft magnetic powder. During the ball milling process, the ball milling beads are zirconium balls with a weight of 1.2 kg and a diameter of 1.6 mm, the ball milling speed is 2500 rpm, and the ball milling time is 7 h. The mass percentage of iron in the soft magnetic material Fe-Mn-Al-P-Co is 41.3, the mass percentage of manganese is 24, the mass percentage of aluminum is 20, the mass percentage of phosphorus is 12.4, and the mass percentage of cobalt is 2.3. S2. Preparation of modified epoxy resin. By mass fraction, the addition amounts of epoxy resin (E-51), 4,4'-diaminodiphenylmethane and benzoxazine are 10:7:5. S21. Add benzoxazine to epoxy resin (E-51), and then stir at a speed of 1000 r / min for 30 min under the condition of 55 °C. S22. Continue to add 4,4 ， -diaminodiphenylmethane to the reaction system and continue stirring for 20 min. S23. Put the well-stirred epoxy resin into a vacuum-pressure impregnation furnace to evacuate for 30 min to obtain modified epoxy resin, with a vacuum degree of 1 mPa; S3. Uniformly disperse the modified soft magnetic powder in the modified epoxy resin, and incorporate p-phenylenediamine. The weight ratio of the modified epoxy resin to the p-phenylenediamine is 6:1, and then perform pressing to obtain a composite soft magnetic material layer; S4. Place the composite soft magnetic material layer in a magnetic field with a magnetic field strength of 2 T for magnetic field orientation induction to obtain a modified composite soft magnetic material layer; S5. Cure the modified composite soft magnetic material layer at 200 °C to obtain a composite soft magnetic material; by weight, the addition amounts of the soft magnetic powder and the modified epoxy resin are 100:1.8.

[0040] Comparative Example 1 Compare Comparative Example 1 with Example 2. The difference between Comparative Example 1 and Example 2 is that the medium for flattening treatment is ethanol.

[0041] Comparative Example 2 Compare Comparative Example 2 with Example 2. The difference between Comparative Example 2 and Example 2 is that the medium for flattening treatment is zirconium balls with a weight of 1.5 kg and a diameter of 2.0 mm, the ball milling speed is 2000 rpm, and the ball milling time is 6 h.

[0042] Comparative Example 3 Compare Comparative Example 3 with Example 2. The difference between Comparative Example 3 and Example 2 is that the epoxy resin is not subjected to modification treatment.

[0043] Comparative Example 4 Compare Comparative Example 4 with Example 2. The difference between Comparative Example 4 and Example 2 is that the composite soft magnetic material is not subjected to magnetic field orientation induction.

[0044] Comparative Example 5 Compare Comparative Example 5 with Example 2. The difference between Comparative Example 5 and Example 2 is that the magnetic field strength for the orientation induction of the composite soft magnetic material is 1.2 T.

[0045] Comparative Example 6 Compare Comparative Example 6 with Example 2. The difference between Comparative Example 6 and Example 2 is that the magnetic field strength for the orientation induction of the composite soft magnetic material is 2.3 T.

[0046] Comparative Example 7 Compare Comparative Example 7 with Example 2. The difference between Comparative Example 7 and Example 2 is that the mass percentage of iron in the soft magnetic material Fe-Mn-Al-P-Co is 40, the mass percentage of manganese is 24, the mass percentage of aluminum is 20, the mass percentage of phosphorus is 12.4, and the mass percentage of cobalt is 3.6.

[0047] Comparative Example 8 Comparing Comparative Example 8 with Example 2, the difference between Comparative Example 8 and Example 2 is that the curing temperature is 140 °C.

[0048] Comparative Example 9 Comparing Comparative Example 9 with Example 2, the difference between Comparative Example 9 and Example 2 is that the curing temperature is 210 °C.

[0049] Comparative Example 10 Comparing Comparative Example 10 with Example 2, the difference between Comparative Example 10 and Example 2 is that the code number of the epoxy resin is E-12.

[0050] Related experiments: The magnetic permeability (GB / T 3655-2008), resistivity (four-probe method), magnetic loss (magnetic spectrum test was carried out using an LCR tester, and loss test was carried out at 200 kHz and B = 20 mT using a broadband power analyzer), and temperature stability (soft magnetic properties were detected at 500-1000 °C) of the soft magnetic materials prepared in the examples and comparative examples were respectively tested. The test results are shown in Table 1.

[0051] Table 1: Detection results of soft magnetic properties One or more technical solutions in the embodiments of the present application at least further have the following technical effects or advantages: (1) Under the technical solution of the present application, the prepared composite soft magnetic material has good mechanical properties and mechanical properties, and does not conflict with the soft magnetic properties.

[0052] (2) The composite soft magnetic material prepared in the present application has excellent soft magnetic properties, has a high magnetic permeability and resistivity, and also has excellent temperature stability. Under high-frequency conditions, the magnetic loss is low, which reduces energy waste, reduces temperature rise, and prolongs the service life of the equipment.

Claims

1. A composite soft magnetic material, characterized in that, The composite soft magnetic material includes Fe-Mn-Al-P-Co soft magnetic powder. After flattening the Fe-Mn-Al-P-Co soft magnetic powder, the flattened soft magnetic powder is then evenly dispersed in the modified epoxy resin, and then the composite soft magnetic material is prepared through pressing and curing.

2. The composite soft magnetic material according to claim 1, characterized in that, In the soft magnetic material Fe-Mn-Al-P-Co, the mass percentage of iron is 41.3, the mass percentage of manganese is 24, the mass percentage of aluminum is 20, the mass percentage of phosphorus is 12.4, and the mass percentage of cobalt is 2.

3.

3. A composite soft magnetic material according to claim 1, characterized in that, The flattening treatment is to place the Fe-Mn-Al-P-Co soft magnetic powder in a ball milling device and add an appropriate amount of ethylene glycol for ball milling.

4. A composite soft magnetic material according to claim 3, characterized in that, During the ball milling process, the ball milling beads are zirconium balls with a weight of 1.2 kg and a diameter of 1.3 - 1.6 mm. The ball milling speed is 2500 rpm, and the ball milling time is 6 - 7 h.

5. The preparation method of a composite soft magnetic material according to claim 1, characterized in that, The preparation method of the modified epoxy resin includes the following steps: S31: Add benzoxazine to epoxy resin (E-51), and then under the condition of 55 °C, stir at a speed of 1000 r / min for 20 - 30 min; S32. Continue to add 4,4 ， -diaminodiphenylmethane to the reaction system and continue stirring for 15 - 20 min; S33: Put the stirred modified epoxy resin into a vacuum-pressure impregnation furnace to evacuate for 20 - 30 min, and the vacuum degree is 1 mPa.

6. A composite soft magnetic material according to claim 5, characterized in that, By mass fraction, the addition amounts of the epoxy resin (E-51), 4,4'-diaminodiphenylmethane, and benzoxazine are 10 - 13:4 - 7:2 - 5.

7. A composite soft magnetic material according to claim 6, characterized in that, Before curing, the soft magnetic material is subjected to magnetic field orientation induction treatment, and the magnetic field strength is 1.5 - 2 T.

8. A method for preparing a composite soft magnetic material according to any one of claims 1 to 7, characterized in that, It includes the following steps: S1: After flattening the Fe-Mn-Al-P-Co soft magnetic powder, flaky soft magnetic powder is obtained; S2. Modify the epoxy resin with benzoxazine and 4,4 ， -diaminodiphenylmethane to obtain a modified epoxy resin; S4: Evenly disperse the flaky soft magnetic powder in the modified epoxy resin, incorporate p-phenylenediamine, and then press. Cure the pressed soft magnetic material to obtain the composite soft magnetic material.

9. The preparation method of a composite soft magnetic material according to claim 8, characterized in that, By weight part, the addition amounts of the soft magnetic powder and the modified epoxy resin are 100:1.3 - 1.

8.

10. The preparation method of a composite soft magnetic material according to claim 8, characterized in that, The curing temperature is 150 - 200 °C.

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