A soft magnetic composite material, a preparation method and application thereof

Abstract

The application belongs to the technical field of soft magnetic powder cores, and particularly relates to a soft magnetic composite material, a preparation method and application thereof. The application provides a preparation method of a soft magnetic composite material, which comprises the following steps: (1) mixing a soft magnetic material and phosphoric acid to obtain a soft magnetic material coated with a phosphate; and (2) mixing the soft magnetic material coated with the phosphate and hyperbranched polysiloxane resin, and then pressing and annealing; the hyperbranched polysiloxane resin comprises at least one of an epoxy-terminated hyperbranched polysiloxane resin and an amino-terminated hyperbranched polysiloxane resin. The soft magnetic composite material prepared by the application has low magnetic loss.

Description

Technical Field

[0001] This invention belongs to the field of soft magnetic powder core technology, specifically relating to a soft magnetic composite material, its preparation method, and its application. Background Technology

[0002] Currently, electronic components are increasingly developing towards higher frequencies, higher power, miniaturization, and higher efficiency, placing higher demands on the resistivity, DC bias characteristics, saturation magnetic flux density, and high-frequency loss characteristics of soft magnetic powder cores. Among these, metallic soft magnetic materials have relatively low resistivity, and their eddy current losses are generally reduced through insulation coating processes.

[0003] Common insulating coatings are divided into inorganic and organic coatings. Inorganic coatings mainly include phosphating coatings, Al2O3 insulating coatings, and MgO insulating coatings. Compared with Al2O3 and MgO insulating coatings, phosphating coatings have a simpler coating process, but they crystallize or decompose at high temperatures, resulting in poor heat resistance. Organic coatings mainly include epoxy resins, bismaleimide resins, and silicone resins. Among them, epoxy resins and bismaleimide resins have excellent adhesion and are easy to process, but they have disadvantages such as being brittle after high-temperature curing, having poor thermal conductivity, and having a high degree of crosslinking that reduces the toughness and ductility of soft magnetic materials. The coating layer formed by linear alkyl polysiloxane resins has good heat resistance, but its adhesion to inorganic coating layers is poor, resulting in poor coating effect. It requires coupling agent treatment before coating, which is a cumbersome process. Existing technologies use phosphating coating followed by pressing and molding. High pressure causes the coating layer to crack, affecting heat resistance. Furthermore, phosphating coating is prone to crystallization or decomposition at high temperatures, resulting in poor heat resistance. Existing technologies also have poor adhesion between organosilicon coating and inorganic coating layers. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects of existing soft magnetic materials after phosphating coating, such as easy cracking during the pressing process affecting heat resistance, easy crystallization or decomposition of phosphating coating layer at high temperature, poor heat resistance, and poor adhesion between organosilicon coating layer and inorganic coating layer, so as to provide a soft magnetic composite material, its preparation method and application.

[0005] To this end, the present invention provides the following technical solution.

[0006] This invention provides a method for preparing a soft magnetic composite material, comprising the following steps:

[0007] (1) Mix the soft magnetic material with phosphoric acid to obtain a phosphate-coated soft magnetic material;

[0008] (2) The phosphate-coated soft magnetic material and hyperbranched polysiloxane resin are mixed, pressed and annealed;

[0009] The hyperbranched polysiloxane resin includes at least one of terminal epoxy hyperbranched polysiloxane resin and terminal amino hyperbranched polysiloxane resin.

[0010] The soft magnetic composite material prepared by this invention has low magnetic loss. It features a hyperbranched polysiloxane resin coating layer over a phosphate coating layer, exhibiting dual-layer properties of both an inorganic phosphate coating and a hyperbranched polysiloxane resin organic coating. This results in excellent coating effect, good high-temperature resistance, and improved molding performance. The hyperbranched polysiloxane resin coating layer effectively reduces crystallization or decomposition of the phosphate coating layer at high temperatures and cracking during pressing, and also provides better adhesion, exhibiting superior bonding with the phosphate coating layer.

[0011] In one alternative implementation, step (1) involves mixing the soft magnetic material with phosphoric acid, a process that requires the addition of a solvent.

[0012] The solvent can be acetone, which serves to dilute and disperse the solvent.

[0013] In one optional embodiment, the mass ratio of the phosphate-coated soft magnetic material to the hyperbranched polysiloxane resin is 100:(0.5-4). As an example, the mass ratio of the phosphate-coated soft magnetic material to the hyperbranched polysiloxane resin can be 100:0.5, 100:1, 100:1.4, 100:1.8, 100:2, 100:2.5, 100:3, 100:3.5, 100:4, or within any range of two of the above values.

[0014] In one alternative embodiment, the hyperbranched polysiloxane resin is mixed with the phosphate-coated soft magnetic material in solution form.

[0015] In one optional embodiment, the preparation step of the hyperbranched polysiloxane resin solution includes: mixing the hyperbranched polysiloxane resin and a solvent.

[0016] Preferably, the mass ratio of the hyperbranched polysiloxane resin to the solvent is (1-4):1;

[0017] Preferably, the solvent includes at least one of acetone, ethanol, and ethyl acetate.

[0018] The preparation method of the terminal epoxy hyperbranched polysiloxane resin specifically includes: adding deionized water and γ-glycidoxypropyltrimethoxysilane (KH-560) to a three-necked flask at a molar ratio of (1.1-2):1, adding hydrochloric acid dropwise while stirring, controlling the pH value to 5.5-6.9, hydrolyzing at room temperature for about 0.5 h, heating to 50-60℃ and refluxing for 3-7 h, and drying the liquid in a vacuum drying oven to obtain the terminal epoxy hyperbranched polysilane resin.

[0019] The preparation method of the terminal amino hyperbranched polysiloxane resin specifically includes: adding deionized water and γ-aminopropyltriethoxysilane (KH-550) to a three-necked flask at a molar ratio of (1.1-2):1, adding hydrochloric acid dropwise while stirring, controlling the pH value to 5.5-6.9, hydrolyzing at room temperature for about 0.5 h, heating to 50-60℃ and refluxing for 3-7 h, and drying the liquid in a vacuum drying oven to obtain the terminal amino hyperbranched polysilane resin.

[0020] In one optional embodiment, the mass ratio of the soft magnetic material to phosphoric acid is 100:(0.1-5). As an example, the mass ratio of the soft magnetic material to phosphoric acid can be 100:0.1, 100:0.5, 100:1, 100:1.5, 100:2, 100:2.5, 100:3, 100:3.5, 100:4, 100:4.5, 100:5, or within any two of the above values.

[0021] In one optional embodiment, the soft magnetic material comprises soft magnetic metal powder;

[0022] Preferably, the metal soft magnetic powder includes at least one of iron-silicon powder, iron-silicon-aluminum powder, iron-nickel powder, iron-nickel-molybdenum powder, and iron-cobalt powder;

[0023] Preferably, the particle size of the metal soft magnetic powder is -200 to +800 mesh.

[0024] In one optional implementation, step (1) further includes drying after mixing;

[0025] Preferably, the drying temperature is 60-100℃. As an example, the drying temperature can be 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, or a range consisting of any two of these values.

[0026] In one optional embodiment, step (2) further includes drying after mixing to obtain an organic layer-coated soft magnetic material;

[0027] Preferably, the drying temperature is 60-100℃. As an example, the drying temperature can be 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, or within any two of the above values.

[0028] In one optional embodiment, step (2) further includes sieving before drying, wherein the mesh size of the sieve is 50-100 mesh;

[0029] In one optional embodiment, step (2) further includes adding a release agent and mixing before pressing;

[0030] Preferably, the release agent comprises at least one of zinc stearate, magnesium stearate, and aluminum stearate;

[0031] Preferably, the mass ratio of the soft magnetic material to the release agent is 100:(0.1-0.5).

[0032] In one optional embodiment, the pressing pressure is 1000-1500 MPa. As an example, the pressing pressure can be 1000 MPa, 1100 MPa, 1200 MPa, 1300 MPa, 1400 MPa, 1500 MPa, or within any two of these values.

[0033] In one optional embodiment, the annealing temperature is 600-800°C; as an example, the annealing temperature can be 600°C, 630°C, 650°C, 680°C, 700°C, 720°C, 750°C, 770°C, 800°C, or within any two of the above values.

[0034] In one alternative implementation, the annealing is performed under a protective atmosphere;

[0035] Preferably, the protective atmosphere includes at least one of a nitrogen atmosphere and an inert atmosphere;

[0036] In one optional implementation, the annealing time is 30-120 minutes. As an example, the annealing time can be 30 minutes, 50 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes, 120 minutes, or within any two of the above values.

[0037] The present invention also provides a soft magnetic composite material prepared by the above preparation method.

[0038] The present invention also provides an application of the soft magnetic composite material prepared by the above preparation method in magnetic materials.

[0039] The technical solution of this invention has the following advantages:

[0040] 1. The method for preparing the soft magnetic composite material provided by the present invention includes the following steps: (1) mixing the soft magnetic material with phosphoric acid to obtain a phosphate-coated soft magnetic material; (2) mixing the phosphate-coated soft magnetic material with a hyperbranched polysiloxane resin, pressing, and annealing; wherein the hyperbranched polysiloxane resin includes at least one of terminal epoxy group hyperbranched polysiloxane resin and terminal amino group hyperbranched polysiloxane resin. The soft magnetic composite material prepared by the present invention has low magnetic loss; it has dual-layer properties of an inorganic phosphate coating layer and a hyperbranched polysiloxane resin organic coating layer, and the coating effect is good. Phosphate coating is a simple process with excellent coating performance. Hyperbranched polysiloxane resin is a polymer material composed of Si-O-Si bonds on the main chain and organic groups on the side groups. Compared with linear alkyl polysiloxane resin, it has more organic groups, superior mechanical properties, better compatibility with magnetic powder, better adhesion, and is easier to form a highly cross-linked film, thereby improving the dispersibility, flame retardancy, moisture resistance, and insulation of the magnetic powder. Hyperbranched polysiloxane resin has high molecular chain flexibility and low intermolecular forces, resulting in good flowability and uniform coating. It also has characteristics such as low glass transition temperature, low surface tension, excellent mechanical properties, and abundant cavities. The abundant cavities further improve the dispersibility of the magnetic powder and achieve uniform coating. The use of hyperbranched polysiloxane resin coating can form a protective layer on top of the phosphate coating layer, which improves the molding performance of magnetic materials, reduces the crystallization and decomposition of the phosphate coating layer at high temperatures and reduces cracking during the pressing process, thus improving the heat resistance of magnetic materials; at the same time, the bonding force between the hyperbranched polysiloxane resin coating and the phosphate coating layer is better.

[0041] Hyperbranched polysiloxane resins possess an inorganic polysiloxane backbone and organic functional groups. Specifically, amino-terminated polysiloxane resins contain an inorganic polysiloxane backbone, amino and hydroxyl functional groups; epoxy-terminated hyperbranched polysiloxane resins contain an inorganic polysiloxane backbone, organic epoxy and hydroxyl functional groups. The inorganic polysiloxane backbone exhibits excellent heat resistance, dielectric properties, and corrosion resistance; while the organic epoxy and hydroxyl, amino and hydroxyl functional groups can all provide adhesion, reacting at high temperatures to form a highly cross-linked film. The resulting three-dimensional network structure can effectively enhance the strength of high-temperature magnetic powder. Hyperbranched polysiloxane resins also possess the characteristics of silane coupling agents. The epoxy or amino groups selected in this invention can react with the hydroxyl groups on the surface of the inorganic coating layer to form chemical bonds, exhibiting good compatibility and improving adhesion to the inorganic coating layer. Simultaneously, the presence of numerous highly active groups at the ends allows for the self-curing of films by hydroxyl groups formed during high temperatures and hydrolysis. This method is simple and also improves heat resistance stability. After uniform coating, the electrical resistance increases while the magnetic loss decreases, indicating that the soft magnetic composite material prepared by this invention has good magnetic properties. The terminal groups in amino-terminated polysiloxane resins are amino groups, while the terminal groups in epoxy-terminated hyperbranched polysiloxane resins are epoxy groups.

[0042] Hyperbranched polysiloxane resin also has good solubility and low surface energy. It only needs to be mixed with a small amount of organic solvent to prepare a slurry with good flowability to coat magnetic powder in situ. The process is simple, and the resulting magnetic powder core has low cost, good high temperature resistance, low loss and good corrosion resistance.

[0043] 2. The method for preparing soft magnetic composite materials provided by the present invention can completely decompose organic groups by annealing at 600-800℃ for 30-120min, achieving full inorganic coating. The process is simple and, compared with single-layer inorganic coating, can more effectively isolate eddy current paths and improve the magnetic properties of magnetic materials. Detailed Implementation

[0044] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0045] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0046] Preparation method of terminal epoxy group hyperbranched polysilane resin: Deionized water and γ-glycidyl etheroxypropyltrimethoxysilane (KH-560) were added to a three-necked flask at a molar ratio of 2:1. Hydrochloric acid was added dropwise while stirring to control the pH value to 5.5-6.9. Hydrolysis was carried out at room temperature for 0.5 h, and the temperature was raised to 55 °C and refluxed for 5 h. The liquid was then dried in a vacuum drying oven to obtain terminal epoxy group hyperbranched polysilane resin.

[0047] Preparation method of amino-terminated hyperbranched polysilane resin: Deionized water and γ-aminopropyltriethoxysilane (KH-550) were added to a three-necked flask at a molar ratio of 2:1. Hydrochloric acid was added dropwise while stirring, and the pH value was controlled at 5.5-6.9. Hydrolysis was carried out at room temperature for 0.5 h, and the temperature was raised to 55 °C and refluxed for 5 h. The liquid was then dried in a vacuum drying oven to obtain epoxy-terminated hyperbranched polysilane resin.

[0048] Example 1

[0049] This embodiment provides a method for preparing a soft magnetic composite material, including the following steps:

[0050] (1) Dissolve 1g of phosphoric acid (AR reagent grade, Sinopharm Chemical Reagent Co., Ltd.) in acetone, add 100g of -300 mesh iron-silicon-aluminum magnetic powder and stir. After mixing evenly, phosphate-coated magnetic powder is obtained and dried in an 80℃ forced-air drying oven. The composition of the iron-silicon-aluminum magnetic powder is 90wt% Fe, 4.5wt% Si and 5.4wt% Al.

[0051] (2) Take 2g of 50wt% terminal epoxy hyperbranched polysilane resin solution (solvent is acetone), add the prepared phosphate-coated magnetic powder, stir at 40℃ for 30min to obtain organic layer coated magnetic powder, sieve through 100 mesh screen to form granules, and place in a 100℃ forced air drying oven to dry.

[0052] (3) Based on the mass of iron-silicon-aluminum magnetic powder, add 0.5% zinc stearate, stir evenly, press at 1200MPa, and anneal at 700℃ in a nitrogen atmosphere for 60 minutes to obtain soft magnetic composite material.

[0053] Example 2

[0054] This embodiment provides a method for preparing a soft magnetic composite material. Compared with Example 1, the only difference is that in step (2), 4g of 50wt% end-epoxy hyperbranched polysilane resin solution is used instead of 2g of 50wt% end-epoxy hyperbranched polysilane resin solution in Example 1.

[0055] Example 3

[0056] This embodiment provides a method for preparing a soft magnetic composite material. Compared with Example 1, the only difference is that in step (2), 6g of 50wt% end-epoxy hyperbranched polysilane resin solution is used instead of 2g of 50wt% end-epoxy hyperbranched polysilane resin solution in Example 1.

[0057] Example 4

[0058] This embodiment provides a method for preparing a soft magnetic composite material. Compared with Example 1, the only difference is that in step (2), 8g of 50wt% end-epoxy hyperbranched polysilane resin solution is used instead of 2g of 50wt% end-epoxy hyperbranched polysilane resin solution in Example 1.

[0059] Example 5

[0060] This embodiment provides a method for preparing a soft magnetic composite material, including the following steps:

[0061] (1) Dissolve 4g of phosphoric acid (AR reagent grade, Sinopharm Chemical Reagent Co., Ltd.) in ethanol, add 100g of +700 mesh iron-nickel magnetic powder and stir. After mixing evenly, phosphate-coated magnetic powder is obtained and placed in a 100℃ forced-air drying oven for drying. The iron-nickel magnetic powder has the composition of 50wt% Fe and 50wt% Ni.

[0062] (2) Take 2g of 80wt% amino-terminated hyperbranched polysilane resin solution (solvent is acetone), add the prepared phosphate-coated magnetic powder, stir at 40℃ for 30min to obtain organic layer coated magnetic powder, sieve through 50 mesh to form granules, and place in a 60℃ forced air drying oven to dry.

[0063] (3) Based on the mass of iron-nickel magnetic powder, add 0.5% zinc stearate, stir evenly, press at 1500MPa, and anneal at 600℃ in a nitrogen atmosphere for 120min to obtain soft magnetic composite material.

[0064] Comparative Example 1

[0065] This comparative example provides a method for preparing a soft magnetic material. Compared with Example 4, the only difference is that step (2) is different. Step (2) is as follows:

[0066] Dissolve 0.2g KH560 in isopropanol, add the prepared phosphate-coated magnetic powder, mix well, and dry in a 100℃ forced-air drying oven; add 6g of 50wt% terminal epoxy linear polysilane resin solution (E875446, Maclean's reagent) (solvent is acetone), stir at 40℃ for 30min to obtain organic layer coated magnetic powder, sieve through a 100-mesh sieve to form granules, and dry in a 100℃ forced-air drying oven.

[0067] Comparative Example 2

[0068] This comparative example provides a method for preparing a soft magnetic material, including the following steps:

[0069] (1) Dissolve 1g of phosphoric acid (AR reagent grade, Sinopharm Chemical Reagent Co., Ltd.) in acetone, add 100g of -300 mesh iron-silicon-aluminum magnetic powder and stir. After mixing evenly, phosphate-coated magnetic powder is obtained and dried in an 80℃ forced-air drying oven. The composition of the iron-silicon-aluminum magnetic powder is 90wt% Fe, 4.5wt% Si and 5.4wt% Al.

[0070] (2) Based on the mass of iron-silicon-aluminum magnetic powder, add 0.5% zinc stearate, stir evenly, press at 1200MPa, and anneal at 700℃ in a nitrogen atmosphere for 60min to obtain soft magnetic material.

[0071] Comparative Example 3

[0072] This comparative example provides a method for preparing a soft magnetic material, including the following steps:

[0073] (1) 8g of 50wt% terminal epoxy hyperbranched polysilane resin solution (solvent is acetone) and 100g of -300 mesh iron-silicon-aluminum magnetic powder are stirred at 40℃ for 30min to obtain organic layer coated magnetic powder. The powder is sieved through a 100 mesh sieve to form granules and then dried in a 100℃ forced-air drying oven. The composition of the iron-silicon-aluminum magnetic powder is 90wt% Fe, 4.5wt% Si and 5.4wt% Al.

[0074] (2) Based on the mass of iron-silicon-aluminum magnetic powder, add 0.5% zinc stearate, stir evenly, press at 1200MPa, and anneal at 700℃ in a nitrogen atmosphere for 60min to obtain soft magnetic material.

[0075] Test case

[0076] The performance of the soft magnetic composite materials prepared in Examples 1-4 and the soft magnetic materials prepared in Comparative Examples 1-2 was tested, as follows:

[0077] (1) Test method of magnetic permeability: The magnetic permeability was measured at 100kHz and 1V using the SY-8218B-H tester. The results are shown in Table 1.

[0078] (2) Test method for magnetic loss: At 500kHz, magnetic field strength of 50mT and temperature of 25℃, the magnetic loss was measured by the SY-8218B-H tester. The results are shown in Table 1.

[0079] (3) Test method for high temperature resistance: The soft magnetic composite material was placed in a constant temperature chamber at 250℃ and left to stand for 250h, 500h and 1000h respectively. The magnetic permeability and magnetic loss (500kHz, 50mT) were tested. The results are shown in Table 2.

[0080] Table 1 Test results for each embodiment and comparative example

[0081] Group number Magnetic permeability (H / m) Magnetic loss (500kHz, 50mT) Example 1 85.7 495.5 Example 2 78.2 488.3 Example 3 70.6 475.6 Example 4 59.5 515.3 Example 5 106.2 507.5 Comparative Example 1 69.8 545.3 Comparative Example 2 83.6 645.3 Comparative Example 3 84.9 578.7

[0082] As shown in Table 1, the soft magnetic composite material prepared by the method of the present invention has low magnetic loss.

[0083] A comparison of Example 4 and Comparative Example 1 shows that the preparation of soft magnetic materials by coating with terminal epoxy linear polysilane resin and coupling agent is complicated, and the magnetic properties of the soft magnetic materials obtained are not as good as those of the soft magnetic composite materials prepared in this invention.

[0084] As shown in Examples 4 and Comparative Examples 2-3, the soft magnetic composite material prepared by this invention possesses dual-layer properties of an inorganic phosphate coating layer and a hyperbranched polysiloxane resin organic coating layer, resulting in excellent coating performance. Compared to Comparative Example 2, which only has a phosphate coating layer, Comparative Example 3, with its hyperbranched polysiloxane resin coating layer, exhibits lower magnetic loss and better magnetic properties.

[0085] Table 2 Comparison of magnetic properties after high-temperature static test.

[0086]

[0087] As shown in the table above, after 1000 hours of high-temperature test at 250℃, the soft magnetic composite material prepared by this invention has better heat resistance. After standing in a constant temperature chamber at 250℃ for 250-1000 hours, the difference in magnetic permeability and magnetic loss is not significant.

[0088] As can be seen from the comparison of Examples and Comparative Examples 2-3, the soft magnetic materials prepared without the preparation method of the soft magnetic composite material provided by the present invention exhibit a significantly increased rate of magnetic loss growth and magnetic permeability decrease.

[0089] Specifically, in Comparative Example 2, which only had a phosphate coating, the phosphate coating was prone to crystallization and decomposition at high temperatures, and the magnetic loss increased significantly as the standing time increased.

[0090] Comparative Example 3, which only has a hyperbranched polysiloxane resin coating, showed a much lower increase in magnetic loss than Comparative Example 2, indicating that the hyperbranched polysiloxane resin coating has better heat resistance than the phosphate coating.

[0091] As can be seen from Examples 2 and 3, when the phosphate coating layer and the hyperbranched polysiloxane resin coating layer are combined, the problem of easy crystallization or decomposition of the phosphate coating layer at high temperature can be effectively solved, thus improving the heat resistance of the soft magnetic composite material.

[0092] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a soft magnetic composite material, characterized in that, Includes the following steps: (1) Mix the soft magnetic material with phosphoric acid to obtain a phosphate-coated soft magnetic material; (2) The phosphate-coated soft magnetic material and hyperbranched polysiloxane resin are mixed, pressed and annealed; The hyperbranched polysiloxane resin includes at least one of terminal epoxy hyperbranched polysiloxane resin and terminal amino hyperbranched polysiloxane resin.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the phosphate-coated soft magnetic material to the hyperbranched polysiloxane resin is 100:(0.5-4).

3. The preparation method according to claim 2, characterized in that, The hyperbranched polysiloxane resin is mixed with the phosphate-coated soft magnetic material in solution form.

4. The preparation method according to claim 1, characterized in that, The mass ratio of the soft magnetic material to phosphoric acid is 100:(0.1-5).

5. The preparation method according to claim 4, characterized in that, The soft magnetic material includes soft magnetic metal powder; Preferably, the metal soft magnetic powder includes at least one of iron-silicon powder, iron-silicon-aluminum powder, iron-nickel powder, iron-nickel-molybdenum powder, and iron-cobalt powder; Preferably, the particle size of the metal soft magnetic powder is -200 to +800 mesh.

6. The preparation method according to claim 1, characterized in that, In step (2), before pressing, a release agent is added and mixed. Preferably, the release agent comprises at least one of zinc stearate, magnesium stearate, and aluminum stearate; Preferably, the mass ratio of the soft magnetic material to the release agent is 100:(0.1-0.5).

7. The preparation method according to claim 1, characterized in that, The pressing pressure is 1000-1500 MPa.

8. The preparation method according to claim 1, characterized in that, The annealing temperature is 600-800℃; and / or, The annealing is performed under a protective atmosphere; and / or, The annealing time is 30-120 minutes.

9. The soft magnetic composite material prepared by the preparation method according to any one of claims 1-8.

10. The application of the soft magnetic composite material prepared by the preparation method according to any one of claims 1-8 in magnetic materials.

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