Soft magnetic composite material with low loss, high magnetic conductivity and high mechanical strength and preparation method thereof

Abstract

The invention discloses a soft magnetic composite material with low loss, high magnetic conductivity and high mechanical strength and a preparation method thereof, and belongs to the technical field of soft magnetic composite materials. According to the FeSiCr magnetic powder core, the surfaces of the FeSiCr particles are phosphatized through phosphoric acid, the oxidation resistance and the chemical stability are enhanced, then the modified material composed of the high-conductivity MnZn ferrite particles and the polysilazane resin is coated, a multi-layer core-shell structure is formed, the magnetic conductivity and the mechanical strength of the FeSiCr magnetic powder core are improved, and loss is reduced. And the requirements of high-frequency integration and high reliability in the fields of inductors, high-frequency transformers, energy storage elements, electromagnetic shielding and the like are met.

Description

Technical Field

[0001] The present invention belongs to the technical field of soft magnetic composite materials, and particularly relates to a soft magnetic composite material with low loss, high magnetic permeability and high mechanical strength and a preparation method thereof. Background Art

[0002] As an important soft magnetic composite material, magnetic powder cores are widely used in inductors, high-frequency transformers, energy storage components, electromagnetic shielding and other fields due to their excellent magnetic properties. Among many magnetic powder core materials, iron-silicon-chromium (FeSiCr) magnetic powder cores have gradually become the preferred materials for high-frequency applications due to their relatively high magnetic permeability and low losses. However, FeSiCr magnetic powder cores still face the following challenges in practical applications: (1) Eddy current loss problem: As the application frequency increases, the eddy current loss of FeSiCr magnetic powder cores increases significantly, resulting in a decrease in the core efficiency. Especially in the frequency band of several hundred kHz to MHz, the eddy current loss has become a key factor restricting its application and affecting the further improvement of its high-frequency performance. (2) Insufficient antioxidant and chemical stability: In high-temperature or humid environments, the surface of FeSiCr magnetic powder is prone to oxidation, generating iron oxide (Fe2O3) or other non-magnetic oxides. These oxides not only reduce the magnetic properties of the magnetic powder core but may also affect the bonding strength and stability between magnetic powder particles. (3) Optimization between high-frequency characteristics and magnetic permeability: To reduce high-frequency losses, insulating agents in a high-resistance state are often used to coat and modify the magnetic powder, such as silicone resin, magnesium aluminum silicate, phosphoric acid, etc. However, the introduction of these insulating agents can improve the insulation characteristics but usually significantly reduces the magnetic permeability. (4) Insulation and thermal stability problems: High-frequency applications require not only good electrical insulation of the magnetic powder core but also high mechanical strength in high-temperature environments.

[0003] In response to the above problems, CN 113410020A discloses a FeSiCr magnetic powder core and a preparation method thereof. The method first treats FeSiCr alloy powder in a phosphating solution to obtain FeSiCr magnetic powder coated with a phosphating layer; subsequently, sodium silicate and fluosilicic acid are added with water to prepare a modified sodium silicate solution, and then the FeSiCr magnetic powder coated with a phosphating layer is added thereto for a second coating modification to form a FeSiCr magnetic powder with a double coating of a phosphating layer - sodium silicate layer. After pressing, curing and annealing treatments, a FeSiCr magnetic powder core is finally obtained. This method significantly improves the resistivity of the FeSiCr magnetic powder core through secondary coating modification and effectively reduces the eddy current loss at high frequencies. However, this process inevitably introduces more non-magnetic phase substances, resulting in a decrease in the magnetic properties between magnetic powder particles.

[0004] CN 112185640A discloses a method for coating metal magnetic powder cores with sodium silicate. This method involves mixing a sodium silicate solution with metal magnetic powder, followed by drying, and then adding inorganic oxides such as alumina and calcium oxide for adhesive coating. After pressing and annealing, magnetic powder cores are finally obtained. Although this process can produce magnetic powder cores with certain properties, the resulting oxide coating layer is a brittle phase with poor wettability with the magnetic powder. During the pressing process, the coating layer is prone to cracking, resulting in the inability to fully exert its performance, especially in terms of the suppression effect of eddy current loss.

[0005] CN 115798854A discloses a low-chromium rust-proof FeSiCr magnetic powder core and its preparation method. In its preparation, the FeSiCr alloy powder is first passivated with a diluent and a passivating agent, and then coated with a low-melting-point silicone resin. While reducing the Cr content, a small amount of Mn element is added to improve the core density and magnetic permeability while basically maintaining the DC superposition characteristics unchanged. After passivating the FeSiCr alloy, a fluidized coating process is used, followed by coupling coating. The prepared low-chromium FeSiCr magnetic powder core can achieve the same rust-proof effect as high-chromium ones. However, due to the use of a low-melting-point silicone resin in its preparation method, the magnetic powder core has poor high-temperature resistance. In addition, although the incorporation of Mn element in the alloy improves the core density and magnetic permeability, the improvement effect is limited and cannot meet the development requirements of increasingly miniaturized, high-magnetic-permeability, and high-power power inductors.

[0006] These studies reveal the feasibility of improving the performance of FeSiCr magnetic powder cores through multi-layer coating modification, and also expose the limitations of existing technologies in terms of magnetic properties and eddy current loss suppression. Future research needs to further optimize the materials and processes of the coating layer to achieve better comprehensive performance. Summary of the Invention

[0007] The object of the present invention is to propose a low-loss, high-magnetic-permeability, and high-mechanical-strength soft magnetic composite material and its preparation method in view of the problems existing in the background technology. The present invention is prepared by coating FeSiCr particles after phosphating treatment with MnZn ferrite having high magnetic permeability and high-temperature-resistant polysilazane resin, and has a multi-layer core-shell structure, aiming to improve magnetic properties and mechanical strength and reduce losses, etc.

[0008] Core idea of the present invention: Adopt multi-layer composite coating, a basic antioxidant layer of phosphated FeSiCr magnetic powder; a high magnetic permeability functional layer of high-conductivity MnZn ferrite; a high-insulation and high-mechanical-strength protective layer of polysilazane resin: (1) Improve antioxidant performance: Improve the antioxidant property of the magnetic powder surface through phosphating treatment, reduce the formation of oxides, and improve the long-term stability of the magnetic powder core; (2) Optimize magnetic properties: Introduce high-conductivity MnZn ferrite particles as the coating layer to further improve the initial magnetic permeability and saturation magnetization intensity of the magnetic powder core, and at the same time suppress eddy current loss at high frequencies; (3) Enhance high-temperature resistance and mechanical strength: Compared with traditional silicone resin binders (generally <600 °C), the polysilazane resin can withstand temperatures up to 1000 °C. In a high-temperature environment, the structure and properties of the polysilazane resin coating layer can remain relatively stable and are not prone to problems such as decomposition and deformation. This is because its main chain takes Si-N bonds as repeating units, with a relatively high bond energy and a relatively stable molecular structure, which can resist the damage caused by high temperatures. In addition, the main chain of polysilazane takes Si-N bonds as repeating units. Compared with the Si-O bonds of silicone resin, the bond energy of Si-N bonds is higher, which makes the molecular structure of polysilazane resin more stable; when subjected to external forces, more energy is required to break or deform the molecular chains, thus showing relatively high mechanical strength. At the same time, the polysilazane resin can form a highly cross-linked three-dimensional network structure during the curing process, with a relatively high cross-linking density. Although silicone resin is also a highly cross-linked structure, due to factors such as the characteristics of Si-O bonds in its molecular structure and the cross-linking method, its cross-linking density and the tightness of the three-dimensional network structure are relatively lower than those of polysilazane resin, so its mechanical strength is also relatively weaker. This tight structure of the polysilazane resin enhances the intermolecular interaction force and can better resist the action of external forces, which macroscopically shows relatively high mechanical strength.

[0009] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] A low-loss, high-magnetic-permeability, high-mechanical-strength soft magnetic composite material is obtained by coating phosphated FeSiCr metal powder with high-conductivity MnZn ferrite and high-temperature-resistant polysilazane resin, and has a multi-layer core-shell structure, where the inner core is FeSiCr particles, the middle layer is a phosphating layer, and a coating modification material formed by high-conductivity MnZn ferrite particles and polysilazane resin coats the surface of the phosphated FeSiCr particles to form an outer shell.

[0011] Furthermore, in the FeSiCr particles, Si accounts for 4.0 - 6.0 wt%, Cr accounts for 4.0 - 6.0 wt%, and the rest is Fe; the high-conductivity MnZn ferrite includes a main formula and additives, and the mass ratio of the main formula to the additives is 19:1. The main formula is Mn 0.6 Zn 0.4Fe2O4, based on the mass of the main formulation, the additives include 0.01 wt.% CaCO3, 0.02 wt.% TiO2, and 0.01 wt.% BiO3.

[0012] Further, the particle size of the FeSiCr particles is 5 - 10 μm, the particle size of the high-permeability MnZn ferrite particles is 0.01 - 0.5 μm, and the initial permeability is 6000 - 12000.

[0013] A preparation method of a low-loss, high-permeability, and high-mechanical-strength soft magnetic composite material includes the following steps:

[0014] Step 1. Phosphatization:

[0015] Weigh the FeSiCr particles, then add the FeSiCr particles into the phosphating solution for phosphating treatment. After phosphating is completed, wash away the residual phosphoric acid and dry to obtain the phosphated FeSiCr.

[0016] Step 2. Coating:

[0017] Add polysilazane resin, high-permeability MnZn ferrite, and KH550 silane coupling agent into acetone, stir and mix evenly, then add the phosphated FeSiCr particles obtained in Step 1, and continuously stir until the acetone completely volatilizes, and then dry in an oven to obtain the FeSiCr magnetic powder coated with high-permeability MnZn ferrite and polysilazane resin.

[0018] Step 3. Sieving:

[0019] Sieve the FeSiCr magnetic powder coated with high-permeability MnZn ferrite and polysilazane resin obtained in Step 2, and then place it in an oven for drying.

[0020] Step 4. Pressing:

[0021] Press the dried magnetic powder in Step 3 into a ring to obtain a magnetic powder core blank.

[0022] Step 5. Annealing:

[0023] Anneal the magnetic powder core blank obtained by pressing in Step 4 to obtain the soft magnetic composite material.

[0024] Further, in Step 1, the phosphating solution is an acetone solution of phosphoric acid, the content of phosphoric acid in the phosphating solution is 0.1 - 1.0 wt%, and 0.2 - 0.4 mL of the phosphating solution is added for every 1 g of FeSiCr particles; the temperature of the phosphating treatment is 40 - 80 °C, and the phosphating treatment time is 0.25 - 1.0 h.

[0025] Further, in Step 1, acetone is used to wash away the residual phosphoric acid; the drying temperature is 40 - 70 °C, and the drying time is 1.0 - 3.0 h.

[0026] Further, in step 2, based on the mass of the phosphated FeSiCr particles, the dosage of the polysilazane resin is 1.0 - 4.0 wt%, the dosage of acetone is 20 - 50 wt%, the dosage of the high-permeability MnZn ferrite is 0.1 - 5.0 wt%, and the dosage of the KH550 silane coupling agent is 0.05 - 0.20 wt%; the drying temperature in the oven is 40 - 70 °C, and the time is 1.0 - 3.0 h.

[0027] Further, in step 3, it is sieved through 20 - 200 meshes; the drying temperature is 40 - 70 °C, and the drying time is 1.0 - 3.0 h.

[0028] Further, the process of step 4 pressing is as follows: after uniformly mixing the magnetic powder dried in step 3 with the lubricant, it is pressed into a magnetic ring to obtain a magnetic powder core blank; wherein, the lubricant is one of aluminum stearate, metal stearate, molybdenum disulfide or hexagonal boron nitride, the dosage of the lubricant is 0.01 - 0.50 wt% of the mass of the dried magnetic powder, and the pressure for pressing and forming is 1000 - 3000 MPa.

[0029] Further, in step 5, the annealing treatment is carried out under vacuum or protective atmosphere conditions, the annealing temperature is 400 - 600 °C, and the holding time is 0.5 - 2 h.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] 1. The present invention provides a low-loss, high-permeability and high-mechanical-strength soft magnetic composite material and its preparation method. The surface of FeSiCr particles is phosphated with phosphoric acid to enhance the antioxidant property and chemical stability, and then a modified material composed of high-permeability MnZn ferrite particles and polysilazane resin is coated to form a multi-layer core-shell structure, improving the magnetic permeability and mechanical strength of the FeSiCr magnetic powder core and reducing the loss. It meets the high-frequency integration and high-reliability requirements in the fields of inductors, high-frequency transformers, energy storage components, and electromagnetic shielding.

[0032] 2. Compared with the traditional organic binder, the high-temperature-resistant polysilazane resin adopted in the present invention has better thermal stability and mechanical properties, enabling the magnetic powder core to still maintain good performance in a high-temperature working environment. Under the high-temperature annealing condition of 800 °C, the power loss of the magnetic powder core is reduced more significantly compared with the traditional binder. Description of the Drawings

[0033] Figure 1SEM micrographs of the high-permeability MnZn ferrite powder (a) used in Examples 1 to 3, the FeSiCr metal raw powder (b) used in Examples 1 to 3 and the comparative example, the high-permeability MnZn ferrite prepared in Example 2, and the phosphated FeSiCr magnetic powder coated with polysilazane resin (c);

[0034] Figure 2 Flow chart of the preparation method of a low-loss, high-permeability and high-mechanical-strength soft magnetic composite material of the present invention;

[0035] Figure 3 Comparison chart of the densities of the magnetic powder cores prepared in Examples 1 to 3 and the comparative example;

[0036] Figure 4 Comparison chart of the magnetic permeabilities of the magnetic powder cores prepared in Examples 1 to 3 and the comparative example;

[0037] Figure 5 Comparison chart of the total losses of the magnetic powder cores prepared in Examples 1 to 3 and the comparative example. Detailed implementation manners

[0038] To enable those skilled in the art to better understand the technical solution of the present invention, it will be described in more detail through specific examples, but the protection scope of the present invention is not limited to these examples.

[0039] The experimental methods or test methods described in the following examples are all conventional methods unless otherwise specified, and the materials and reagents are all obtained from conventional commercial channels unless otherwise specified.

[0040] A low-loss, high-permeability and high-mechanical-strength soft magnetic composite material and a preparation method thereof provided by the present invention prepare the samples of Examples 1 to 4 and the comparative example through the following steps:

[0041] Example 1:

[0042] A preparation method of a low-loss, high-permeability and high-mechanical-strength soft magnetic composite material includes the following steps:

[0043] 1) Add 200 g of FeSicr alloy powder to the phosphating solution prepared from 1.0 g of phosphoric acid and 60 g of acetone, stir at 50 °C in a water bath for 40 min, then let it stand for 3 min, remove the supernatant, wash the phosphated FeSiCr alloy powder with acetone solution three times, and then place the magnetic powder in an oven at 60 °C and dry for 1 h to obtain the phosphated FeSiCr magnetic powder coated with a phosphating layer;

[0044] 2) Dissolve 0.5 g of high-conductivity MnZn ferrite powder, 6.0 g of polysilazane resin, and 0.2 g of KH550 silane coupling agent in 60 g of acetone solution. After ultrasonic dispersion for 5 min, add 200 g of phosphated FeSiCr magnetic powder coated with a phosphating layer. Stir evenly under the condition of water bath heating at 50 °C until the acetone completely volatilizes. Dry in vacuum at 60 °C for 1 h, then pass through a 80-mesh sieve, and take the powder with a particle size less than 80 mesh to obtain phosphated FeSiCr magnetic powder coated with high-conductivity MnZn ferrite and polysilazane resin;

[0045] 3) Mix the phosphated FeSiCr magnetic powder coated with high-conductivity MnZn ferrite and polysilazane resin and aluminum stearate according to a mass ratio of 1000:5, and then add them into a molding die. Apply a pressure of 1800 MPa and hold the pressure for 30 s to press into a magnetic ring with an outer diameter of 10.0 mm, an inner diameter of 6.0 mm, and a height of 3.0 mm ± 0.2 mm. In an Ar2 atmosphere, control the heating rate to 5 °C / min and heat up to 180 °C, hold for 1 h, then control the heating rate to 5 °C / min and heat up to 600 °C, hold for 1 h, and cool with the furnace to obtain the FeSiCr magnetic powder core.

[0046] Example 2:

[0047] A preparation method of a low-loss, high magnetic permeability, and high mechanical strength soft magnetic composite material, comprising the following steps:

[0048] 1) Add 200 g of FeSicr alloy powder to a phosphating solution prepared from 1.0 g of phosphoric acid and 60 g of acetone. Stir under the condition of a water bath at 50 °C for 40 min, then stand for 3 min, remove the supernatant, and then wash the phosphated FeSiCr alloy powder three times with acetone solution. Then place the magnetic powder in an oven at 60 °C and dry for 1 h to obtain phosphated FeSiCr magnetic powder coated with a phosphating layer;

[0049] 2) Dissolve 1.0 g of high-conductivity MnZn ferrite powder, 6.0 g of polysilazane resin, and 0.2 g of KH550 silane coupling agent in 60 g of acetone solution. After ultrasonic dispersion for 5 min, add 200 g of phosphated FeSiCr magnetic powder coated with a phosphating layer. Stir evenly under the condition of water bath heating at 50 °C until the acetone completely volatilizes. Dry in vacuum at 60 °C for 1 h, then pass through a 80-mesh sieve, and take the powder with a particle size less than 80 mesh to obtain phosphated FeSiCr magnetic powder coated with high-conductivity MnZn ferrite and polysilazane resin;

[0050] 3) Mix the high-permeability MnZn ferrite, the phosphated FeSiCr magnetic powder coated with polysilazane resin, and aluminum stearate in a mass ratio of 1000:5. Then add them to a molding die, apply a pressure of 1800 MPa and hold for 30 s to press them into a magnetic ring with an outer diameter of 10.0 mm, an inner diameter of 6.0 mm, and a height of 3.0 mm ± 0.2 mm. In an Ar₂ atmosphere, control the heating rate to 5 °C / min and heat up to 180 °C, hold for 1 h, then control the heating rate to 5 °C / min and heat up to 500 °C, hold for 1 h, and cool with the furnace to obtain the FeSiCr magnetic powder core.

[0051] Example 3:

[0052] A preparation method of a low-loss, high-permeability, and high-mechanical-strength soft magnetic composite material includes the following steps:

[0053] 1) Add 200 g of FeSiCr alloy powder to a phosphating solution prepared from 1.0 g of phosphoric acid and 60 g of acetone, stir for 40 min under a water bath condition of 50 °C, then let it stand for 3 min, remove the supernatant, wash the phosphated FeSiCr alloy powder with acetone solution three times, and then place the magnetic powder in an oven at 60 °C and dry for 1 h to obtain the phosphated FeSiCr magnetic powder coated with a phosphating layer.

[0054] 2) Dissolve 2.0 g of high-permeability MnZn ferrite powder, 6.0 g of polysilazane resin, and 0.2 g of KH550 silane coupling agent in 60 g of acetone solution, ultrasonically disperse for 5 min, then add 200 g of the phosphated FeSiCr magnetic powder coated with a phosphating layer, stir evenly under a water bath heating condition of 50 °C until the acetone completely evaporates, dry in vacuum at 60 °C for 1 h, then pass through an 80-mesh sieve, and take the powder with a particle size less than 80 mesh to obtain the phosphated FeSiCr magnetic powder coated with high-permeability MnZn ferrite and polysilazane resin.

[0055] 3) Mix the phosphated FeSiCr magnetic powder coated with high-permeability MnZn ferrite and polysilazane resin and aluminum stearate in a mass ratio of 1000:5. Then add them to a molding die, apply a pressure of 1800 MPa and hold for 30 s to press them into a magnetic ring with an outer diameter of 10.0 mm, an inner diameter of 6.0 mm, and a height of 3.0 mm ± 0.2 mm. In an Ar₂ atmosphere, control the heating rate to 5 °C / min and heat up to 180 °C, hold for 1 h, then control the heating rate to 5 °C / min and heat up to 400 °C, hold for 1 h, and cool with the furnace to obtain the FeSiCr magnetic powder core.

[0056] Comparative example:

[0057] A preparation method of a low-loss, high-permeability, and high-mechanical-strength soft magnetic composite material includes the following steps:

[0058] 1) Add 200 g of FeSicr alloy powder to the phosphating solution prepared from 1.0 g of phosphoric acid and 60 g of acetone. Stir for 40 min under the condition of a 50°C water bath, then let it stand for 3 min. Remove the supernatant, and then wash the phosphated FeSiCr alloy powder with acetone solution three times. Then place the magnetic powder in an oven at 60°C and dry it for 1 h to obtain FeSiCr magnetic powder coated with a phosphating layer;

[0059] 2) Dissolve 6.0 g of silicone resin and 0.2 g of KH550 silane coupling agent in 60 g of acetone solution. After ultrasonic dispersion for 5 min, add 200 g of FeSiCr magnetic powder coated with a phosphating layer. Stir evenly under the condition of heating in a 50°C water bath until the acetone completely evaporates. Dry it in vacuum at 60°C for 1 h, and then pass through an 80-mesh sieve. Take the powder with a particle size smaller than 80 mesh to obtain phosphated FeSiCr magnetic powder coated with silicone resin;

[0060] 3) Mix the phosphated FeSiCr magnetic powder coated with silicone resin and aluminum stearate according to a mass ratio of 1000:5, and then add them to a molding die. Apply a pressure of 1800 MPa and hold the pressure for 30 s to press into a magnetic ring with an outer diameter of 10.0 mm, an inner diameter of 6.0 mm, and a height of 3.0 mm ± 0.2 mm. In an Ar2 atmosphere, control the heating rate to be 5°C / min and heat up to 180°C, hold for 1 h, then control the heating rate to be 5°C / min and heat up to 600°C, hold for 1 h, and cool with the furnace to obtain the FeSiCr magnetic powder core.

[0061] After winding the FeSiCr magnetic powder core samples prepared in Examples 1 to 3 and Comparative Example 1, use a Tonghui TH2826 precision LCR tester to measure the inductance L of the samples. Appropriately adjust the voltage at both ends to make B < 0.25 mT, and calculate the effective magnetic permeability of the samples through formula conversion. The test conditions are a frequency f = 10 KHz and a typical voltage value of 10 mV. The density is measured by the Archimedes drainage method. The loss performance is measured by an Iwasaki SY-8218B-H analyzer. The loss test conditions are 1 MHz, 15 mT, and 25°C. The crushing strength test of the material is usually carried out using a universal testing machine. Fix the specimen in the fixture, then apply a certain amount of pressure, record the force suffered by the specimen during deformation and failure in the test process, and then export the force curve. Analyze the quality of the material crushing strength based on the data analysis of the test experiment. The test results are shown in Table 1 below.

[0062] Table 1 Performance test results of FeSiCr magnetic powder cores obtained in examples and comparative examples:

[0063]

[0064] The above results show that, compared with the FeSiCr magnetic powder core insulated only with silicone resin, the magnetic permeability of the FeSiCr magnetic powder core coated with the high-permeability MnZn ferrite and polysilazane resin described in the present invention has increased significantly, by 34.1%. The density has increased and the loss has decreased by 20% under the same conditions. It can effectively improve the magnetic permeability of the FeSiCr magnetic powder core and reduce its loss. At the same time, the crushing strength has increased by 19.2%, enhancing the reliability and safety of the magnetic core.

[0065] The above-described embodiments merely represent specific embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A low-loss, high-permeability, high-mechanical-strength soft magnetic composite material, characterized in that: The invention is obtained by coating phosphating FeSiCr with high-conductivity MnZn ferrite and polysilazane resin, and has a multi-layer core-shell structure, wherein the inner core is FeSiCr particles, the middle layer is a phosphating layer, and the coating modified material formed by high-conductivity MnZn ferrite and polysilazane resin is coated on the surface of the phosphating FeSiCr particles to form an outer shell.

2. The low-loss, high-permeability, high-mechanical-strength soft magnetic composite material according to claim 1, characterized in that: In the FeSiCr particles, Si accounts for 4.0-6.0wt%, Cr accounts for 4.0-6.0wt%, and the rest is Fe; the high-conductivity MnZn ferrite includes a main formula and an additive, the mass ratio of the main formula to the additive is 19:1, the main formula is Mn 0.6 Zn 0.4 Fe2O4, based on the mass of the main formula, the additives include 0.01wt.% CaCO3, 0.02wt.% TiO2 and 0.01wt.% BiO3.

3. The low-loss, high-permeability, high-mechanical-strength soft magnetic composite material according to claim 1, characterized in that: The particle size of the FeSiCr particles is 5-10 μm, the particle size of the high-conductivity MnZn ferrite is 0.01-0.5 μm, and the initial magnetic permeability is 6000-12000.

4. A method for preparing a low-loss, high-permeability, high-mechanical-strength soft magnetic composite material, characterized in that: The following steps are involved: Step 1. Phosphating: Weighing FeSiCr particles, then adding the FeSiCr particles into a phosphating solution for phosphating treatment, and after the phosphating is completed, washing and drying to obtain phosphated FeSiCr; Step 2. Wrapping: Add polysilazane resin, high-conductivity MnZn ferrite and KH550 silane coupling agent to acetone, stir evenly, then add the phosphated FeSiCr particles obtained in step 1, continue stirring until the acetone is completely volatilized, and dry to obtain high-conductivity MnZn ferrite and polysilazane resin coated FeSiCr magnetic powder; Step 3. Sieve: The high-conductivity MnZn ferrite and the FeSiCr magnetic powder coated with polysilazane resin obtained in step 2 are sieved and dried; Step 4. Press: Pressing the magnetic powder dried in step 3 into a shape to obtain a magnetic powder core blank; Step 5. Annealing: The magnetic powder core blank obtained by pressing in step 4 is annealed to obtain the soft magnetic composite material.

5. The method for preparing a low-loss, high-permeability, high-mechanical-strength soft magnetic composite material according to claim 4, characterized in that: In step 1, the phosphating solution is an acetone solution of phosphoric acid, the content of phosphoric acid in the phosphating solution is 0.1-1.0wt%, and 0.2-0.4mL of the phosphating solution is added to every 1g of FeSiCr particles; the phosphating temperature is 40-80°C, and the phosphating time is 0.25-1.0h.

6. The method for preparing a low-loss, high-permeability, high-mechanical-strength soft magnetic composite material according to claim 4, characterized in that: In step 1, acetone is used to clean the residual phosphoric acid; the drying temperature is 40 to 70° C., and the drying time is 1.0 to 3.0 h.

7. The method for preparing a low-loss, high-permeability, high-mechanical-strength soft magnetic composite material according to claim 4, characterized in that: In step 2, based on the mass of the FeSiCr particles after phosphating, the amount of polysilazane resin is 1.0-4.0wt%, the amount of acetone is 20-50wt%, the amount of high-conductivity MnZn ferrite is 0.1-5.0wt%, and the amount of KH550 silane coupling agent is 0.05-0.20wt%; the drying temperature is 40-70°C, and the time is 1.0-3.0h.

8. The method for preparing a soft magnetic composite material with low loss, high magnetic permeability and high mechanical strength according to claim 4, characterized in that: In step 3, the sieve is 20-200 mesh; the drying temperature is 40-70° C., and the drying time is 1.0-3.0 h.

9. The method for preparing a low-loss, high-permeability, high-mechanical-strength soft magnetic composite material according to claim 4, characterized in that: The pressing process of step 4 is as follows: after the magnetic powder dried in step 3 is evenly mixed with the lubricant, it is pressed into a magnetic ring to obtain a magnetic powder core blank; wherein the lubricant is one of aluminum stearate, stearate, molybdenum disulfide or hexagonal boron nitride, and the amount of the lubricant is 0.01 to 0.50wt% of the mass of the dried magnetic powder, and the pressing pressure is 1000 to 3000MPa.

10. The method for preparing the low-loss, high-permeability, high-mechanical-strength soft magnetic composite material according to claim 4, characterized in that: In step 5, the annealing treatment is carried out under vacuum or protective atmosphere conditions, the annealing temperature is 400-600° C., and the holding time is 0.5-2 h.

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