Iron-silicon magnetic material, method for preparing same and use thereof

Abstract

The application belongs to the technical field of soft magnetic material preparation, and particularly relates to a ferrosilicon magnetic material and a preparation method and application thereof. The preparation method comprises the following steps: (1) mixing ferrosilicon magnetic powder and a passivation agent, and then performing primary heat treatment and cooling to room temperature at a speed of not higher than 30 DEG C / h; (2) mixing the magnetic powder obtained in the step (1) with the passivation agent to obtain passivated magnetic powder; (3) adding a first coating agent to the passivated magnetic powder to perform primary coating, and then performing secondary heat treatment; and (4) adding a second coating agent to the magnetic powder obtained in the step (3) to perform secondary coating, pressing, and then performing tertiary heat treatment. The average particle size of the first coating agent is 300 nm-1 mu m; and the second coating agent comprises colloidal particles, and the average particle size of the colloidal particles is not higher than 100 nm. The preparation method can improve the density and effective magnetic permeability of the ferrosilicon magnetic material, so that the ferrosilicon magnetic material has excellent magnetic performance, the loss is greatly reduced, heat generation is reduced, and the device is beneficial to energy saving and high efficiency.

Description

Technical Field

[0001] This invention belongs to the field of soft magnetic material preparation technology, specifically relating to an iron-silicon magnetic material, its preparation method, and its application. Background Technology

[0002] With the development of technology, various soft magnetic powder cores are widely used in new energy, electrical, communication, and automotive industries, requiring them to develop towards miniaturization, intelligence, high integration, and low loss. Currently, the market mainly offers various types of soft magnetic powder cores, including iron powder cores and metal powder cores. Iron powder cores have high saturation magnetic induction and low resistivity, and are typically used in low-frequency bands, but suffer from high eddy current losses at high frequencies. While metal powder cores have significantly lower losses than iron powder cores, their DC superposition characteristics and high-frequency losses still limit their large-scale application. Currently, the main metal powder core used is the iron-silicon powder core. Although iron-silicon powder cores have lower costs and higher DC superposition performance, they have higher losses and generate significant heat, which is detrimental to the energy efficiency and high performance of devices. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the defects of high loss and severe heat generation of existing iron-silicon magnetic powder cores, thereby providing an iron-silicon magnetic material, its preparation method and application.

[0004] To this end, the present invention provides the following technical solution.

[0005] This invention provides a method for preparing an iron-silicon magnetic material, comprising the following steps:

[0006] (1) Iron-silicon magnetic powder is mixed with passivating agent and then cooled to room temperature at a cooling rate of no more than 30℃ / h after one heat treatment.

[0007] (2) The magnetic powder obtained in step (1) is mixed with a passivating agent to obtain passivated magnetic powder;

[0008] (3) Add a first coating agent to the passivated magnetic powder for a first coating and a second heat treatment;

[0009] (4) Add a second coating agent to the magnetic powder obtained in step (3) for secondary coating, press, and heat treatment three times;

[0010] The first coating agent has an average particle size of 300 nm to 1 μm; the second coating agent contains colloidal particles with an average particle size of no more than 100 nm.

[0011] In one optional embodiment, the difference in average particle size between the colloidal particles in the first coating agent and the second coating agent is 200 nm to 1000 nm.

[0012] In one optional embodiment, in step (1), the iron-silicon magnetic powder is gas-atomized iron-silicon magnetic powder;

[0013] The mass ratio of the iron-silicon magnetic powder to the passivating agent is 100:(0.1-0.5); and / or,

[0014] The passivating agent includes at least one of phosphoric acid and aluminum dihydrogen phosphate.

[0015] Optionally, in step (1), the particle size of the gas-atomized iron-silicon magnetic powder is 10μm-40μm.

[0016] In one optional embodiment, the temperature of the primary heat treatment is 650℃-800℃, and the time is 2h-3h. Optionally, when performing step (1), the atmosphere of the primary heat treatment can be any atmosphere such as vacuum, nitrogen, or argon, and the present invention does not specifically limit it.

[0017] In an optional embodiment, step (2) involves the passivating agent comprising at least one of phosphoric acid and aluminum dihydrogen phosphate; and / or,

[0018] The amount of passivating agent used is 0.1wt%-1wt% of the magnetic powder obtained in step (1).

[0019] Optionally, step (2) of mixing further includes adding a solvent, which may be at least one of water, acetone, and ethanol. The amount of solvent used is not required, as long as it can completely wet the magnetic powder. A drying step is also included before obtaining the passivated magnetic powder.

[0020] In an optional embodiment, in step (3), the first coating agent comprises an organosilicon resin; and / or,

[0021] The amount of the first coating agent is 0.1 wt%-1 wt% of the passivated magnetic powder obtained in step (2); and / or,

[0022] The secondary heat treatment is performed at a temperature of 300℃-550℃ for 1-2 hours.

[0023] In step (3), the first coating agent includes silicone resin; the first coating agent serves as both adhesive and insulating agent. Step (3) also includes adding a solvent during the first coating step. The solvent has a low boiling point and can be at least one of acetone and ethanol. The amount of solvent used is not critical, as long as it completely wets the magnetic powder. After the first coating, drying and sieving steps are included, with a sieve mesh size of 80-140 mesh. After the second heat treatment, a sieve step is also included, with a sieve mesh size of 80-140 mesh.

[0024] In an optional embodiment, in step (4), the second coating agent is an insulating adhesive; and / or,

[0025] The amount of the second coating agent added is 1 wt%-2 wt% of the magnetic powder obtained in step (3).

[0026] In one optional embodiment, the pressing pressure is 1500MPa-2000MPa; and / or,

[0027] The three heat treatments are performed at temperatures of 680℃-720℃ for 1-2 hours.

[0028] It should be noted that in step (4), the insulating adhesive comprises 45-80 wt% silica sol, 0.1-3 wt% silane coupling agent, and 20-55 wt% polyurethane; the preparation method of the insulating adhesive includes mixing silica sol, silane coupling agent, and polyurethane to form colloidal particles, thereby obtaining the insulating adhesive. The average particle size of the colloidal particles is preferably not higher than 20 nm. Further, the solid content of the insulating adhesive is 55%-75%. This invention uses colloidal particles with an average diameter not higher than 100 nm for secondary coating, which can better adsorb the particles onto the magnetic powder surface, increasing the insulation effect and reducing losses.

[0029] This invention provides an iron-silicon magnetic material prepared by the above-described method.

[0030] The present invention provides an electronic component comprising the iron-silicon magnetic material prepared by the above-described preparation method.

[0031] The iron-silicon magnetic material of this invention can be used as a key material for electronic components (such as transformers, inductors, etc.), and can effectively store and release electromagnetic energy. The iron-silicon magnetic powder of this invention is mainly used in electronic components operating at low frequencies.

[0032] The technical solution of this invention has the following advantages:

[0033] 1. The present invention provides a method for preparing iron-silicon magnetic materials, comprising: (1) mixing iron-silicon magnetic powder with a passivating agent, performing a heat treatment, and then cooling the mixture to room temperature at a rate not exceeding 30°C / h; (2) mixing the magnetic powder obtained in step (1) with the passivating agent to obtain passivated magnetic powder; (3) adding a first coating agent to the passivated magnetic powder for a first coating, followed by a second heat treatment; (4) adding a second coating agent to the magnetic powder obtained in step (3) for a second coating, pressing, and performing a third heat treatment; wherein the average particle size of the first coating agent is 300 nm-1 μm; and the second coating agent contains colloidal particles, wherein the average particle size of the colloidal particles is not higher than 100 nm. This preparation method can improve the density and effective permeability of iron-silicon magnetic materials, giving them excellent magnetic properties, significantly reducing losses, reducing heat generation, and facilitating energy-saving and high-efficiency devices, while also exhibiting high DC superposition performance. In the preparation of magnetic materials, uneven coating can lead to increased eddy current losses in the magnetic powder. The particle size of the first coating agent is larger than that of the second coating agent. Larger particles are used for coating first, and then smaller particles are used for filling. The large difference in particle size between the two coating agents can form a more uniform coating, avoiding uneven coating of large or small particles, thereby improving insulation performance and reducing losses.

[0034] In preparing the magnetic material, this invention first performs two passivation processes on the iron-silicon magnetic powder to make the passivation surface more uniform, which is beneficial for the subsequent insulating coating effect and allows silicon particles to better adhere to the magnetic powder surface. After the first passivation, the temperature is lowered to room temperature at a rate not exceeding 30℃ / h, which can better release the internal stress of the magnetic powder and help improve the material performance. The passivated magnetic powder is first coated and then subjected to a second heat treatment, which allows other substances in the organosilicon resin to volatilize, reducing impurities. Only silicon particles are coated on the surface of the magnetic powder, which plays a role in bonding and insulation, and prepares for the second coating. The second coating can fill or repair the gaps that appeared during the first coating, making the silicon particle distribution on the surface of the magnetic powder more uniform, achieving a better insulation effect, and thus reducing the loss of magnetic powder. The third treatment is the treatment after the magnetic powder is pressed into a ring. This process removes the glue and releases the internal stress to obtain a suitable FeSi phase, thereby reducing loss and heat generation. Detailed Implementation

[0035] 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.

[0036] 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.

[0037] The preparation methods of the insulating adhesive used in the following examples and comparative examples are as follows:

[0038] The preparation method of insulating adhesive with an average diameter of colloidal particles of 20 nm includes: mixing silica sol (manufacturer and model: Zhejiang Yuda Chemical Silica Sol, Z3-20), polyurethane and silane coupling agent in a mass ratio of 65:35:1 to obtain modified silica sol containing colloidal particles. The solid content of the modified silica sol is about 60 wt%.

[0039] The preparation method of the insulating adhesive liquid with an average diameter of colloidal particles of 30nm includes: mixing silica sol (manufacturer and model: Zhejiang Yuda Chemical Silica Sol, Z3-30), polyurethane and silane coupling agent (KH560) in a mass ratio of 65:35:1 to obtain a modified silica sol containing colloidal particles. The solid content of the modified silica sol is about 60wt%.

[0040] The preparation method of the insulating adhesive liquid with an average diameter of colloidal particles of 50nm includes: mixing silica sol (manufacturer and model: Zhejiang Yuda Chemical Silica Sol, Z3-50), polyurethane and silane coupling agent (KH560) in a mass ratio of 65:35:1 to obtain a modified silica sol containing colloidal particles. The solid content of the modified silica sol is about 60wt%.

[0041] The preparation method of insulating adhesive liquid with an average diameter of colloidal particles of 100nm includes: mixing silica sol (manufacturer and model: Zhejiang Yuda Chemical Silica Sol, Z3-100), polyurethane and silane coupling agent (KH560) in a mass ratio of 65:35:1 to obtain modified silica sol containing colloidal particles. The solid content of the modified silica sol is about 60wt%.

[0042] The preparation method of insulating adhesive liquid with an average diameter of colloidal particles of 200nm includes: mixing silica sol (manufacturer and model: Zhejiang Yuda Chemical Silica Sol, Z3-200), polyurethane and silane coupling agent (KH560) in a mass ratio of 65:35:1 to obtain modified silica sol containing colloidal particles. The solid content of the modified silica sol is about 60wt%.

[0043] The phosphoric acid used in the following examples and comparative examples has a purity of over 99%.

[0044] Example 1

[0045] This embodiment provides a method for preparing an iron-silicon magnetic material, including the following steps:

[0046] (1) Select gas-atomized iron-silicon magnetic powder with a particle size of 30μm, mix it thoroughly with phosphoric acid and put it into a heat treatment furnace. After the furnace temperature is raised to 740℃, keep it at the temperature for 2 hours, and then slowly cool it down to room temperature and take it out of the furnace. The cooling rate is 30℃ / h and the atmosphere inside the furnace is vacuum. The mass ratio of phosphoric acid to gas-atomized iron-silicon magnetic powder is 0.2:100.

[0047] (2) The magnetic powder obtained in step (1) is mixed with phosphoric acid at a mass ratio of 100:0.2, and acetone is added to completely impregnate the magnetic powder. The mixture is then dried at 80°C while being stirred. After drying, passivated magnetic powder is obtained.

[0048] (3) Passivating magnetic powder and organosilicon resin were mixed at a mass ratio of 100:0.5, and acetone was added to completely impregnate the magnetic powder. The mixture was then naturally dried, crushed, and passed through a 140-mesh sieve. The mixture was then placed in a heat treatment furnace and kept at 450°C for 1.5 hours under a nitrogen atmosphere. After cooling to room temperature in the furnace, the mixture was passed through a 140-mesh sieve to obtain primary coated magnetic powder. The average particle size of the organosilicon resin was 400 nm.

[0049] (4) The primary coated magnetic powder and modified silica liquid were mixed at a mass ratio of 100:1, and acetone was added to completely impregnate the magnetic powder. The mixture was then naturally dried, crushed, and passed through a 100-mesh sieve to obtain the secondary coated magnetic powder. The average particle size of the colloidal particles in the modified silica liquid was 20 nm. The secondary coated magnetic powder and zinc stearate release agent were thoroughly mixed at a mass ratio of 100:0.4 and then placed in a press for molding at a molding pressure of 1900 MPa. The mixture was then heat-treated at 700°C for 1 hour under a nitrogen atmosphere and cooled to room temperature in the furnace to obtain the iron-silicon magnetic core.

[0050] Example 2

[0051] This embodiment provides a method for preparing an iron-silicon magnetic material, including the following steps:

[0052] (1) Select gas-atomized iron-silicon magnetic powder with a particle size of 30μm, mix it thoroughly with phosphoric acid and put it into a heat treatment furnace. After the furnace temperature is raised to 740℃, keep it at the temperature for 2 hours, and then slowly cool it down to room temperature and take it out of the furnace. The cooling rate is 30℃ / h and the atmosphere inside the furnace is vacuum. The mass ratio of phosphoric acid to gas-atomized iron-silicon magnetic powder is 0.2:100.

[0053] (2) The magnetic powder obtained in step (1) is mixed with phosphoric acid at a mass ratio of 100:0.2, and acetone is added to completely impregnate the magnetic powder. The mixture is then dried at 80°C while being stirred. After drying, passivated magnetic powder is obtained.

[0054] (3) Passivating magnetic powder and organosilicon resin were mixed at a mass ratio of 100:0.5, and acetone was added to completely impregnate the magnetic powder. The mixture was then naturally dried, crushed, and passed through a 140-mesh sieve. The mixture was then placed in a heat treatment furnace and kept at 450°C for 1.5 hours under a nitrogen atmosphere. After cooling to room temperature in the furnace, the mixture was passed through a 140-mesh sieve to obtain primary coated magnetic powder. The average particle size of the organosilicon resin was 400 nm.

[0055] (4) The primary coated magnetic powder and modified silica liquid were mixed at a mass ratio of 100:1, and acetone was added to completely impregnate the magnetic powder. The mixture was then naturally dried, crushed, and passed through a 100-mesh sieve to obtain the secondary coated magnetic powder. The average particle size of the colloidal particles in the modified silica liquid was 50 nm. The secondary coated magnetic powder and the release agent zinc stearate were thoroughly mixed at a mass ratio of 100:0.4 and then placed in a press for molding at a molding pressure of 1900 MPa. The mixture was then heat-treated at 700°C for 1 hour under a nitrogen atmosphere and cooled to room temperature in the furnace to obtain the iron-silicon magnetic core.

[0056] Example 3

[0057] This embodiment provides a method for preparing an iron-silicon magnetic material, including the following steps:

[0058] (1) Select gas-atomized iron-silicon magnetic powder with a particle size of 30μm, mix it thoroughly with phosphoric acid and put it into a heat treatment furnace. After the furnace temperature is raised to 740℃, keep it at the temperature for 2 hours, and then slowly cool it down to room temperature and take it out of the furnace. The cooling rate is 30℃ / h and the atmosphere inside the furnace is vacuum. The mass ratio of phosphoric acid to gas-atomized iron-silicon magnetic powder is 0.2:100.

[0059] (2) The magnetic powder obtained in step (1) is mixed with phosphoric acid at a mass ratio of 100:0.2, and acetone is added to completely impregnate the magnetic powder. The mixture is then dried at 80°C while being stirred. After drying, passivated magnetic powder is obtained.

[0060] (3) Passivating magnetic powder and organosilicon resin were mixed at a mass ratio of 100:0.5, and acetone was added to completely impregnate the magnetic powder. The mixture was then naturally dried, crushed, and passed through a 140-mesh sieve. The mixture was then placed in a heat treatment furnace and kept at 450°C for 1.5 hours under a nitrogen atmosphere. After cooling to room temperature in the furnace, the mixture was passed through a 140-mesh sieve to obtain primary coated magnetic powder. The average particle size of the organosilicon resin was 400 nm.

[0061] (4) The primary coated magnetic powder and modified silica liquid were mixed at a mass ratio of 100:1, and acetone was added to completely impregnate the magnetic powder. After natural drying, the powder was crushed and passed through a 100-mesh sieve to obtain the secondary coated magnetic powder. The average particle size of the colloidal particles in the modified silica liquid was 100 nm. The secondary coated magnetic powder and zinc stearate release agent were thoroughly mixed at a mass ratio of 100:0.4 and then placed in a press for molding at a molding pressure of 1900 MPa. The mixture was then heat-treated at 700°C for 1 hour under a nitrogen atmosphere and cooled to room temperature in the furnace to obtain the iron-silicon magnetic core.

[0062] Example 4

[0063] This embodiment provides a method for preparing an iron-silicon magnetic material, including the following steps:

[0064] (1) Select gas-atomized iron-silicon magnetic powder with a particle size of 20μm, mix it thoroughly with phosphoric acid, and put it into a heat treatment furnace. After the furnace temperature is raised to 720℃, it is kept at the temperature for 2 hours, and then slowly cooled to room temperature and taken out of the furnace. The cooling rate is 30℃ / h, and the atmosphere inside the furnace is vacuum. The mass ratio of phosphoric acid to gas-atomized iron-silicon magnetic powder is 0.2:100.

[0065] (2) The magnetic powder obtained in step (1) is mixed with phosphoric acid at a mass ratio of 100:0.2, and acetone is added to completely impregnate the magnetic powder. The mixture is then dried at 80°C while being stirred. After drying, passivated magnetic powder is obtained.

[0066] (3) Passivating magnetic powder and organosilicon resin were mixed at a mass ratio of 100:0.7, and acetone was added to completely impregnate the magnetic powder. The mixture was then naturally dried, crushed, and passed through a 140-mesh sieve. The mixture was then placed in a heat treatment furnace and kept at 450°C for 1.5 hours under a nitrogen atmosphere. After cooling to room temperature with the furnace, the mixture was passed through a 140-mesh sieve to obtain primary coated magnetic powder. The average particle size of the organosilicon resin was 500 nm.

[0067] (4) The primary coated magnetic powder and modified silica liquid were mixed at a mass ratio of 100:1, and acetone was added to completely impregnate the magnetic powder. The mixture was then naturally dried, crushed, and passed through a 100-mesh sieve to obtain the secondary coated magnetic powder. The average particle size of the colloidal particles in the modified silica liquid was 30 nm. The secondary coated magnetic powder and the release agent zinc stearate were thoroughly mixed at a mass ratio of 100:0.3 and then placed in a press for molding at a molding pressure of 1800 MPa. The mixture was then heat-treated at 700°C for 1 hour under a nitrogen atmosphere and cooled to room temperature in the furnace to obtain the iron-silicon magnetic core.

[0068] Example 5

[0069] This embodiment provides a method for preparing iron-silicon magnetic materials, which differs from Embodiment 4 in that the annealing temperature in step (3) is 300℃.

[0070] Example 6

[0071] This embodiment provides a method for preparing iron-silicon magnetic materials, which differs from Embodiment 4 in that the annealing temperature in step (3) is 500℃.

[0072] Example 7

[0073] This embodiment provides a method for preparing iron-silicon magnetic materials, which differs from Embodiment 4 in that the annealing temperature in step (3) is 600℃.

[0074] Example 8

[0075] This embodiment provides a method for preparing an iron-silicon magnetic material, including the following steps:

[0076] (1) Select gas-atomized iron-silicon magnetic powder with a particle size of 30μm, mix it thoroughly with phosphoric acid and put it into a heat treatment furnace. After the furnace temperature is raised to 740℃, keep it at the temperature for 2 hours, and then slowly cool it down to room temperature and take it out of the furnace. The cooling rate is 15℃ / h and the atmosphere inside the furnace is vacuum. The mass ratio of phosphoric acid to gas-atomized iron-silicon magnetic powder is 0.1:100.

[0077] (2) The magnetic powder obtained in step (1) is mixed with phosphoric acid at a mass ratio of 100:0.4, and acetone is added to completely impregnate the magnetic powder. The mixture is then dried at 80°C while being stirred. After drying, passivated magnetic powder is obtained.

[0078] (3) Passivating magnetic powder and organosilicon resin were mixed at a mass ratio of 100:0.5, and acetone was added to completely impregnate the magnetic powder. The mixture was then naturally dried, crushed, and passed through a 140-mesh sieve. The mixture was then placed in a heat treatment furnace and kept at 450°C for 1.5 hours under a nitrogen atmosphere. After cooling to room temperature in the furnace, the mixture was passed through a 140-mesh sieve to obtain primary coated magnetic powder. The average particle size of the organosilicon resin was 500 nm.

[0079] (4) The primary coated magnetic powder and modified silica liquid were mixed at a mass ratio of 100:1.5, and acetone was added to completely impregnate the magnetic powder. The mixture was then naturally dried, crushed, and passed through a 100-mesh sieve to obtain the secondary coated magnetic powder. The average particle size of the colloidal particles in the modified silica liquid was 50 nm. The secondary coated magnetic powder and zinc stearate release agent were thoroughly mixed at a mass ratio of 100:0.4 and then placed in a press for molding at a molding pressure of 1900 MPa. The mixture was then heat-treated at 700°C for 1 hour under a nitrogen atmosphere and cooled to room temperature in the furnace to obtain the iron-silicon magnetic core.

[0080] Comparative Example 1

[0081] This comparative example provides a method for preparing iron-silicon magnetic materials, which differs from Example 1 in that the average particle size of the colloidal particles in the modified silica liquid in step (4) is 200 nm.

[0082] Comparative Example 2

[0083] This comparative example provides a method for preparing iron-silicon magnetic materials, which differs from Example 1 in that the average particle size of the organosilicon in step (3) is 100 nm.

[0084] Test case

[0085] This experimental example provides the performance tests and results of the various embodiments and comparative examples of iron-silicon magnetic cores.

[0086] During pressing, the resulting magnetic ring had an outer diameter of 12.7 mm, an inner diameter of 7.6 mm, and a height of 3 mm. The density of the core was tested using the water displacement method. The core was then wound, and the inductance L was measured using LCR (Liquid Crystal Reflectance) to calculate the effective permeability μ of the toroidal core. The test frequency was 100 kHz. The AC loss of the core was tested using a Japanese Iwasaki SY-8218 soft magnetic BH analyzer under the following conditions: 50 kHz, 100 mT, and a temperature of 25 °C.

[0087] Table 1. Performance test results for each embodiment and comparative example.

[0088]

[0089]

[0090] The results above show that the magnetic core prepared by this invention has low loss and can prevent severe overheating. From Examples 1-3, it can be seen that the loss increases significantly with the increase of the average diameter of the colloidal particles in the modified silica gel solution. When the average diameter of the colloidal particles is too high, such as when the average diameter of the colloidal particles in Comparative Example 1 increases to 200 nm, it leads to uneven coating of the magnetic core, resulting in greater loss and negatively impacting the magnetic properties of the core.

[0091] As seen in Examples 4-6, a heat treatment temperature of 300-550℃ after the first coating helps to optimize the loss and permeability of the magnetic core.

[0092] As seen in Comparative Examples 1-2, the present invention performs a first coating on the passivated magnetic powder, followed by a second heat treatment. This allows other substances in the silicone resin to volatilize, reducing impurities. Only silicon particles remain coated on the surface of the magnetic powder, providing adhesion and insulation. This also prepares the material for the second coating, which can fill or repair gaps that appeared during the first coating. This results in a more uniform distribution of silicon particles on the surface of the magnetic powder, achieving better insulation and reducing the loss of the magnetic powder.

[0093] 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 an iron-silicon magnetic material, characterized in that, Includes the following steps: (1) Iron-silicon magnetic powder is mixed with passivating agent and then cooled to room temperature at a cooling rate of no more than 30℃ / h after one heat treatment; (2) The magnetic powder obtained in step (1) is mixed with a passivating agent to obtain passivated magnetic powder; (3) Add a first coating agent to the passivated magnetic powder for a first coating and a second heat treatment; (4) Add a second coating agent to the magnetic powder obtained in step (3) for secondary coating, press, and perform a third heat treatment; The first coating agent has an average particle size of 300 nm to 1 μm; the second coating agent contains colloidal particles, the average particle size of which is not higher than 100 nm. The temperature of the first heat treatment is 650℃-800℃, and the time is 2h-3h; The secondary heat treatment is performed at a temperature of 300℃-550℃ for 1-2 hours. The three heat treatments are performed at temperatures of 680℃-720℃ for 1-2 hours.

2. The preparation method according to claim 1, characterized in that, The difference in average particle size between the colloidal particles in the first coating agent and the second coating agent is 200nm-1000nm.

3. The preparation method according to claim 1, characterized in that, In step (1), the iron-silicon magnetic powder is gas-atomized iron-silicon magnetic powder. The mass ratio of the iron-silicon magnetic powder to the passivating agent is 100:(0.1-0.5); and / or, The passivating agent includes at least one of phosphoric acid and aluminum dihydrogen phosphate.

4. The preparation method according to claim 1, characterized in that, In step (2), the passivating agent includes at least one of phosphoric acid and aluminum dihydrogen phosphate; and / or, The amount of passivating agent used is 0.1wt%-1wt% of the magnetic powder obtained in step (1).

5. The preparation method according to claim 1, characterized in that, In step (3), the first coating agent comprises silicone resin; and / or, The amount of the first coating agent is 0.1wt%-1wt% of the passivated magnetic powder obtained in step (2).

6. The preparation method according to claim 1, characterized in that, In step (4), the second coating agent is an insulating adhesive liquid; and / or, The amount of the second coating agent added is 1wt%-2wt% of the magnetic powder obtained in step (3).

7. The preparation method according to claim 1, characterized in that, The pressing pressure is 1500MPa - 2000MPa.

8. The iron-silicon magnetic material prepared by the preparation method according to any one of claims 1-6.

9. An electronic component, characterized in that, Including the iron-silicon magnetic material prepared by the preparation method according to any one of claims 1-7.

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